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`United States Patent 15
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`Koderaet al.
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`[54] METHOD FOR PLANARIZING A
`SEMICONDUCTOR DEVICE HAVING A
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`AMORPHOUS LAYER
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`[75]
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`Inventors: Masako Kodera, Kawasaki, Japan;
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`Hiroyuki Yano, Wappingers Falls,
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`N.Y.; Atsushi Shigeta, Yamato,
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`Japan; Riichirou Aoki, Tokyo, Japan;
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`Hiromi Yajima, Yokohama, Japan;
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`
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`Haruo Okano, Tokyo, Japan
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`[73] Assignee:
`
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`
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`Kabushiki Kaisha Toshiba, Kawasaki,
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`Japan
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`[21] Appl. No.: 66,375
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`[22] Filed:
`May 25, 1993
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`Foreign Application Priority Data
`[30]
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`© May 26, 1992 [JP]
`Japan 0... eee eeeeeseseeereeee 4-132978
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`Sep. 25, 1992 [JP]
`Japan...
`a 4-256889
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`Oct. 20, 1992 [JP]
`Japan...
`. 4-281194
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`Nov. 30, 1992 [JP]
`Japan ...
`wu. 4319175
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`Dec. 11, 1992 [JP]
`Japan wo. eesceeeeseeneeees 4-331945
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`[51] Unt, C16 ooo eeeeceesccssee HOIL 21/302; HOIL 21/463
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`P52] US. Che coecsccccsssscssseeseesseesseeesee 437/225; 437/101;
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`437/966; 437/235
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`[58] Field of Search ..........0. 156/636; 437/228, 966,
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`437/960, 225, 101, 637
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`
`[56]
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`
`
`References Cited
`U.S. PATENT DOCUMENTS
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`3,715,842 2/1973 Tredinnick et al. ........ 51/303
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`6/1987 Beyer et al. osc 156/645
`4,671,851
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`
`US005445996A.
`
`
`
`[11] Patent Number:
`
`
`
`
`[45] Date of Patent:
`
`
`5,445,996
`
`
`Aug. 29, 1995
`
`
`
`
`
`.
`
`4,735,679 4/1988 Laske ........scessceescessesccenecenees 437/62
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`4,879,258 11/1989 Fisher.........
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`3/1990 Cote et al.
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`4,940,507
`7/1990 Harbarger .......
`eee 156/636
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`
`7/1991 Sandhu et al. oes 437/8
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`
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`
`5,064,683 11/1991 Poon et ab. cc
`essessteeeseeee 427/39
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`5/1992 Priggeetal. ...
`.. 204/129.3
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`
`5,166,096 11/1992 Cote et al... eee
`eeeeeee+ 437/195
`
`
`
`
`
`
`
`8/1993 Otsu ....cccrcccsscccccsessenesotscseeses 437/67
`5,236,861
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`5,246,884
`9/1993 Jaso etal. ...
`. 437/225
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`
`
`
`5,262,346 11/1993 Bindal et al.
`. 156/636
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`
`
`
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`
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`5,272,117 12/1993 Roth et al...eeeeeeeeeeeees 437/228
`
`
`
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`
`0272531A1
`6/1988 European Pat. Off.
`.
`
`
`
`
`
`0403287A2 12/1990 European Pat. Off.
`.
`
`
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`
`
`63-266830 11/1988 Japan .
`
`
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`
`
`
`
`Primary Examiner—Olik Chaudhuri
`
`
`
`
`Assistant Examiner—H. Jey Tsai
`
`
`
`
`Attorney, Agent, or Firm—Finnegan, Henderson,
`
`
`
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`Farabow, Garrett & Dunner
`
`
`
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`
`
`
`ABSTRACT
`[57]
`
`
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`
`
`To planarize an insulating film formed on a semiconduc-
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`
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`tor substrate, a polishing slurry containing cerium oxide
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`is used to polish the surface ofthe insulating film. Using
`
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`the cerium oxide included slurry as a polishing agent,
`
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`
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`the insulating film is not contaminated by alkali metals
`
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`
`
`
`
`during the polishing process. Furthermore, the insulat-
`
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`
`
`
`ing film is polished at an enhanced polishing rate.
`
`
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`
`
`1 Claim, 41 Drawing Sheets
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`234
`
`CZZB3C AW
`XsMAY
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` 234=235
`
`LLEVAIIE
`NSSAANSSAAAS
` S 233
`232
`
`
`
`201
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`Page 1 of 64
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`TSMC Exhibit 1035
`TSMCv. IP Bridge
`IPR2016-01246
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`Page 1 of 64
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`TSMC Exhibit 1035
`TSMC v. IP Bridge
`IPR2016-01246
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`

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`U.S. Patent
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`Aug. 29, 1995
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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 2 of 41
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`5,445,996
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`FIG.
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`2A
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`PRIOR ART
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`2B
`FIG.
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`PRIOR ART
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`FIG 2C GAS8e<S2S
`X_N
`VN
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`PRIOR ART AAaAAAAANY
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`13
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`U.S. Patent
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`Sheet 3 of 41
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`5,445,996
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`PORTION
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`RECESSED ~*
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`30
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`60
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`90
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`120
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`DISTANCE(Hm)
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`POLISHING TIME
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`(sec.)
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`FIG 4
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`PRIOR ART
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`U.S. Patent
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`Sheet 4 of 41
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`5,445,996
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`FIG SA
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`PRIOR ART
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`5B
`FIG.
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`PRIOR ART
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`LTAAaA
`
`ANlefa
`CEACN
`77? Do
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`FIG.
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`5C
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`SSSSESssy
`LLAAaAAa
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`FIG 5D
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`PRIOR ART
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`Page 5 of 64
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`U.S. Patent
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`Sheet 5 of 41
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`5,445,996
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`DISTANCE
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`RECESSED
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`PORTION
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`(fm)
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`120
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`30
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`60
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`90
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`POLISHING TIME
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`(sec)
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`6
`FIG.
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`PRIOR ART
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`U.S. Patent
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`Aug, 29, 1995
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`Sheet 6 of 41
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`5,445,996
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`WASNOS
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`SOMOS
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`32
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`33
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`320
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`34
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`32
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`FIG 7A
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`PRIOR ART
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`36
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`35
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`VVVVIIII
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`32
`33.
`32
`34
`32
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`FIG 7B
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`PRIOR ART
`
`{
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`42
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`43
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`42
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`42
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`FIG 8A
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`PRIOR ART
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`FIG 8B
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`PRIOR ART
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`Page7 of 64
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`Sheet 7 of 41
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`5,445,996
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`FIG 9A
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`PRIOR ART
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`g ZL).
`Z
`_¢
`ATA AA 83
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`INNNN
`ANASAG
` AAACT
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`9B
`FIG.
`
`
`PRIOR ART
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` PNNONNON PYANASS
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`FIG 9C
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`PRIOR ART
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`U.S. Patent
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`Sheet 8 of 41
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`5,445,996
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`FIGAOA
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`PRIOR
`
`ART
`
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`FIG.AOB
`
`PRIOR
`
`ART
`
`65
`
`
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`65
`63
`
`
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`CNRRLMAS
`7 7164
`Df
`(/ LW. JW.
`
`FIGIOC: RYNCNENSINRNNWLNNQher
`
`
`PRIOR
`|
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`ART
`
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`ERIACIO IOe 6
`FIGIOD PNNNNNOENIQAARASN
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`PRIOR
`{
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`ART
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`Page 9 of 64
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`Sheet 9 of 41
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`5,445,996
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`"
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`{
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`73
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`re
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`{
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`73
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`if
`{
`
`FIG 41A
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`PRIOR ART
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`FIG {1B
`PRIOR ART
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`FIG 41C
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`PRIOR ART
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`Sheet 10 of 41
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`5,445,996
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`~
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`3
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`82
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`{
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`62
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`{
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`93
`82
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`{
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`82
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`84
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`84
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`83
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`FIG 12A
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`PRIOR ART
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`42B
`FIG.
`PRIOR ART
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`FIG 412C
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`PRIOR ART
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`i2D
`FIG.
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`PRIOR ART
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`12E
`FIG.
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`PRIOR ART
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`Sheet 11 of 41
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`5,445,996
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`43
`FIG.
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`PRIOR ART
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`203
`202
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`FIG {19A i
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`FIG. 19D
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`203
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`V7
`V7) A ~204
`205
`VLSLL/LLLLL3 203
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`EASAAS0 302
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`FIG.
`{9B
`201
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`SSE REE
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`203
`202
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`FIG.
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`19C
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`FIG.
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`{19E
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`205
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`202
`201
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`FIG 19F
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`Sheet 12 of 41
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`5,445,996
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`14
`FIG.
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`PRIOR ART
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`MOTORCURRENT
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`MOTORCURRENT — °
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`POWER SUPPLY
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`VOLTAGE
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`FIG {5
`PRIOR ART
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`Page 13 of 64
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`0
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`LOAD
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`16
`FIG.
`|
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`PRIOR ART
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`Sheet 13 of 41
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`LN
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`JOVLSONINYOM+3ov1sWILINI
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`0000
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`000S
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`POLISHING RATE (A/min)
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`Page 14 of 64
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`oo!os
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`(uw)
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`HLO1)ONIHSI10d40ONISN403WIL
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`08Ov
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`POLISHING RATE (pm/min)
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`Page 15 of 64
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`Sheet 15 of 41
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`FIG. 20B
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`FIG 20C
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`Page 16 of 64
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`U.S. Patent
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`Ang. 29, 1995
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`FIG. 21C
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`i 207
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`Page 17 of 64
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`Page 17 of 64
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`120
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`90
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`150
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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 17 of 41
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`DISTANCE
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`FIG. 22
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`Page 18 of 64
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`Sheet 18 of 41
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`DISTANCE(#m) -RAISED
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`120
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`150
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`90
`60
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`POLISHING TIME (sec.)
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`FIG 23
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`Page 19 of 64
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`Page 19 of 64
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`U.S. Patent
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`Sheet 19 of 41
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`RAISED
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`POLISHING TIME (sec.)
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`150
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`120
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`FIG. 24
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`Page 20 of 64
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`Page 20 of 64
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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 20 of 41
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`a)
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`POLISHING TIME
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`(sec.)
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`FIG 25
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`Page 21 of 64
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`Page 21 of 64
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`U.S. Patent
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`Sheet 21 of 41
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`(#m)
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`POLISHING TIME (sec.)
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`FIG 26
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`Page 22 of 64
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`Page 22 of 64
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`U.S. Patent
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`Sheet 22 of 41
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`\
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`POLISHING TIME (sec.)
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`FIG 27
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`Page 23 of 64
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`Page 23 of 64
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`Aug, 29, 1995
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`Sheet 23 of 41
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`201
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`217
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`FIG 28
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`Page 24 of 64
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`Page 24 of 64
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`U.S. Patent
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`Sheet 24 of 41
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`4v
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`FIG 29C
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`Page 25 of 64
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`Page 25 of 64
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`Sheet 25 of 41
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`7KekeASAI
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`FIG 30B
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`(ASDLLIER
`KRY)‘LAA
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`FIG 30C
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`WEA YX
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`FIG 314A
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`Page 26 of 64
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`Page 26 of 64
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`U.S. Patent
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`Ang. 29, 1995
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`Sheet 26 of 41
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`\VZUANNYZighlLLekLLLYUWI
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`FIG 318
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`FIG 32A
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`VASES
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`FIG 328
`CALEAFAEA 233
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`ARAAANISSAAAN
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`FIG 32C
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` oarrr tf
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`231
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`231
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`Page 27 of 64
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`Page 27 of 64
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`Aug. 29, 1995
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`Sheet 27 of 41
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`PIIIIYSD, 203202
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`4Sf/f
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`PL7)SEAR
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`FIG. 33A
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`FIG 336
`OLLLLLZp202
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`FIG oe
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`hhaSSLSS
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`246
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`FIG 33H
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`202
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`yo
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`FIG. 33F
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`Page 28 of 64
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`FIG 33d
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`Page 28 of 64
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`Sheet 28 of 41
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`FIG 34E
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`Page 29 of 64
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`Page 29 of 64
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`Sheet 29 of 41
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`{OO0rpm
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`LOAD 40Kgf
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`FIG. 35
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`Page 30 of 64
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`Sheet 30 of 41
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`CURRENT THROUGH MOTOR (A)
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`FIG.36
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`(min.)
`
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`POLISHINGTIME
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`120
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`80
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`POLISHING RATE (um/min.)
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`Page 31 of 64
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`Page 31 of 64
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`Sheet 31 of 41
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`MOTOR
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`CURRENTTHROUGH
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`Mm N = ©
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`oOo GoGo
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`Page 32 of 64
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`FIG37
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`(A)
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`Page 32 of 64
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`Sheet 32 of 41
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`5,445,996
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`POLISHINGRATE(um/min)
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`600
`
`
`
`
`FRICTION BETWEEN TURNTABEL AND
`
`
`
`TO-BE-POLISHED LAYER (N)
`
`
`
`FIG. 38
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`Page 33 of 64
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`Page 33 of 64
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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 33 of 41
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`5,445,996
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`0.8
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`NUMBER OF ROTATION OF TURNTABLE AND
`
`
`
`HOLDING DEVICE
`(rpm.)
`
`
`
`FIG 39
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`Page 34 of 64
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`Page 34 of 64
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`US. Patent
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`Sheet 34 of 41
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`FIG. 4
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`Page 35 of 64
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`Page 35 of 64
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`US. Patent
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`Aug, 29, 1995
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`Sheet 35 of 41
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`5,445,996
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`Uw;AALS
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`Page 36 of 64
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`Page 36 of 64
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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 36 of 41
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`5,445,996
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`
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`CONTROLLER 611
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`
`
` SETTING OF
`
`
`
`POLISHING
`
`CONDITIONS
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`CALCULATING
`OF F/Fq
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`RE-SETTING
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`POLISHING
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`
`CONDITIONS
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`FIG 45
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`Page 37 of 64
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`Page 37 of 64
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`

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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 37 of 41
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`5,445,996
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`FIG.46
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`
`
`(A)
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`CURRENTTHROUGHDRIVINGMOTOR
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`5000
`POLISHING RATE (A/min)
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`©O
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`o©©
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`Page 38 of 64
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`Page 38 of 64
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`

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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 38 of 41
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`5,445,996
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`
`
`000SOmaeQn7TOTOm=9=ORMOM00000!
`o00rYLee000%Fee
`002osI00!0g0Q0
`0009
`
`
`
`POLISHING AMOUNT (
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`A)
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`0002
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`0006
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`°
`POLISHING RATE (A/min)
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`Page 39 of 64
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`
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`(UI!W)HLOTDONIHSI10d40ONISN40JWIL
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`Zp914
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`Page 39 of 64
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`

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`U.S. Patent
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`
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`Aug, 29, 1995
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`Sheet 39 of 41
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`5,445,996
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`FIG.48
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`TIMEOFUSINGOFPOLISHINGCLOTH(min)
`
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`150200
`
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`100
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`
`50
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`= .
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`ie)
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`w
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`10000
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`
`POLISHING RATE (A/min)
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`Page 40 of 64
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`CURRENT THROUGH DRIVING MOTOR (A)
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`Page 40 of 64
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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 40 of 41
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`5,445,996
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`503
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`FIG. 49
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`104
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`703
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`702
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`Page 41 of 64
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`Page 41 of 64
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`U.S. Patent
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`Aug. 29, 1995
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`Sheet 41 of 41
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`5,445,996
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`FIG31
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`TIMEOFUSINGOFPOLISHINGCLOTH(min)
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`150
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`200
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`100
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`o)
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`©c
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`OLISHING RATE (A/min)
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`Page 42 of 64
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`250300
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`Page 42 of 64
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`

`

`METHOD FOR PLANARIZING A
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`SEMICONDUCTOR DEVICE HAVING A
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`AMORPHOUS LAYER
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`2
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`an amine. This type of polishing slurry is, however,
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`accompanied by a problem of an unpractically low
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`polishing speed if used for silicon oxide films.
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`On the other hand, a well known methodofpolishing
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`the surface of glass photo-masks comprises steps of
`BACKGROUND OF THE INVENTION
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`primary polishing using a suspension of aluminum oxide
`1. Field of the Invention
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`and finish polishing using another suspension containing
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`cerium oxide particles having an averageparticlesize of
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`This invention relates to a polishing apparatus and a
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`several micrometers. However, such a two-step polish-
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`method for planarizing a layer on a semiconductor wa-
`fer.
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`ing operation involved in the process of manufacturing
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`semiconductor devices is not recommendable by any
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`2. Description of the Related Art
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`means, considering the fact that an insulating film needs
`Conventionally, colloidal silica is popularly used as a
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`polishing slurry for polishing and planarizing the sur-
`to be polished to reduce its thickness by only several
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`face of insulating films or the like in the process of
`micrometers. Furthermore, in the process of manufac-
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`manufacturing semiconductor devices.
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`turing semiconductor devices,an insulating film layeris
`often formed on the surface of a semiconductor sub-
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`There are used colloidal silica granules of a diameter
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`as large as tens of several nanometers. The granules are
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`strate that carries raised portions (conductive layers)
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`normally obtained by growing sodiumsilicate in water.
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`having a height of several hundreds to thousands nano-
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`Obtained granuloussilica is then mixed with water to
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`meters. Such differences in height of the surface of a
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`form a suspension or colloidal silica, to which KOH or
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`semiconductordevice will be clearly reflected onto the
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`NaOHis added to regulate the hydrogen ion concentra-
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`profile of the insulating film formed thereon. The step
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`tion of the suspension and at the same time achieve an
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`configuration of the surface of the insulating film need
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`enhanced polishing efficiency for the slurry.
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`to be planarized by polishing. However,it has notatall
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`Compol-80 marketed by Fujimi Corporationis one of
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`been knownfor sure if cerium oxide particles having an
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`commercially available polishing slurries of the above
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`average size of several micrometers can successfully
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`described type containing an alkali metal. Whena sili-
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`polish and planarize the surface that has a configuration
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`con oxide film is polished or scraped byusingtheslurry,
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`of different heights of several hundreds to thousands
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`the alkali metal contained in the slurryis at least partly
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`nanometers and if the insulating film will be contami-
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`dispersed into thesilicon oxide film or the semiconduc-
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`nated by the alkali metal as in the case where colloidal
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`tor device. When the device is a MOS device, the dis-
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`silica is used. All in all, the above described method of
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`persed metal fluctuates the threshold voltage level of
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`polishing the surface of a glass layer operating as a
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`the device to significantly reduce thereliability of the
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`photo-mask has been developed without taking into
`semiconductor device.
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`consideration if it can be applied to the operation of
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`In order to avoid this problem, some preventive mea-
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`polishing semiconductor devices during the manufac-
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`sures need to be taken such as additionally forming a
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`turing process.
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`protective film layer under the silicon oxide film to
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`The above conventional methods of polishing semi-
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`block dispersion of alkali metal, making the overall
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`conductor devices, using colloidalsilica or the like as a
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`process of manufacturing semiconductordevices rather
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`polishing slurry, are accompanied by the problem of
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`cumbersome and complicated.
`40
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`contamination by alkali metal and that of a slow polish-
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`Now, howaprior art semiconductor device is pro-
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`ing rate.
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`duced will be briefly described by referring to illustra-
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`While a method of using a suspension that does not
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`tions showing its sectional views in various stages of
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`contain cerium oxide particles is also known in the
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`preparation. FIG. 1A of the accompanying drawings
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`illustrates a conventional semiconductor device com-
`technology of polishing the surface of glass photo-
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`masks, it is not certain at all if such a method can polish
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`prising a semiconductor substrate 1 and electrode or
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`and planarize a surface having a profile of steps of sev-
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`wire patterns designated by reference numeral 2. To
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`eral hundreds to thousands nanometers high andifit is
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`protect the patterns, a protective film3is firstly formed
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`not accompanied by a problem of metal contamination.
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`on the entire surface area of the semiconductor struc-
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`Again, it is a method that has been developed without
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`ture, and subsequently a resist 4 is applied onto the film
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`taking into consideration if it can be applied to the oper-
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`3 and thentheresist 4 is subjected to a patterning opera-
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`ation of polishing semiconductor devices during the
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`tion by using a lithographic technique, as illustrated in
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`manufacturing process.
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`FIG. 1B. Thereafter, the protective film 3 is selectively
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`Now,a typical knownpolishing and planarizing tech-
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`removed as the resist 4 is used as masks. Thereafter, the
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`nique of the category under consideration will be de-
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`resist 4 is removed to produce a patterned protective
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`scribed by referring to FIGS. 2A through 2C of the
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`film as shown in FIG. 1C. Thereafter, as illustrated in
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`accompanying drawings. Asillustrated in FIG. 2A, a
`FIG. 1D,a silicon oxide film 5 is formed on the semi-
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`semiconductor device is prepared by forming an SiO2
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`conductor structure, and then its surface is planarized
`film 12 on an Si semiconductor device 1 and then a
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`using a polishing method to producea planarsurface, as
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`metal wires 13 having a thickness of 1.1 m are appro-
`shown in FIG. 1E. However, the above conventional
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`priately formed on the SiO: film 12 to produce a given
`method additionally requires the steps of FIGS. 1A
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`pattern of metal wires.
`through 1C, thus complicating the entire manufacturing
`process.
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`Thereafter, another SiO? film 14 is formed on the
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`There is also used another polishing slurry of the
`entire surface of the above intermediate product. Con-
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`colloidal silica series containing no alkali metal. The
`sequently, the surface of the second SiOz layer shows
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`slurry is obtained by performing pyrolysis ofsilicic acid
`raised portions and recessed portions, reflecting the
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`tetrachloride or hydrolysis of organic silane to grow
`pattern of metal wires. Then, the surface of the second
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`silica particles, and regulating the hydrogen ion concen-
`$iO2 layer 14 is polished to remove the raised and re-
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`tration of the produced silica by means of ammonia or
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`cessed portions. The operation of polishing or scraping
`
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`10
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`15
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`35
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`45
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`Page 43 of 64
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`the surface of the second SiO? layer 14 will be carried
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`out by using a polishing apparatusasillustrated in FIG.
`3
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`5,445,996
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`4
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`Such a method of forming a thick film and polishing
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`off the film is, however, very time consuming and hence
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`increases the manufacturing cost. Moreover, the more
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`the film is polished, the greater becomesthe fluctuations
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`in the polishing speed on the film, a phenomenon by no
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`means favorable for the polishing operation.
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`The above described dishing phenomenon for the
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`recessed portions can be prevented by forming, for
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`instance, a silicon nitride film as a “polish stopper” for
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`the recessed portions in order to suppress the rate of
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`polishing the SiOz film 14 at the recessed portions and
`increase the rate at which the difference in the thickness
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`of the SiO? film 14 at the raised and recessed portionsis
`reduced.
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`This technique is schematically illustrated in FIGS.
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`5A through 5D, which show a semiconductorstructure
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`in cross section. Referring firstly to FIG. 5A, an SiO2
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`film 12 is formed on an Si substrate and (1.1 wm thick)
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`metal wires 13 are formed thereon in a manner as de-
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`scribed before.
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`Thereafter, another SiOz film 14 is formed on the
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`entire surface of the intermediate product as shownin
`FIG. 5B.
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`Then, a silicon nitride film 15 is formed on the SiO2
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`film 14 and subsequently is subjected to a patterning
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`operation, in which, as shown in FIG. 5C,the silicon
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`nitride film 15 is removed except at the recessed por-
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`tions where no metal wires are formed under the SiO2.
`film 14.
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`Finally, the surface of the SiOz film 14 is polished by
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`using a polishing apparatusas illustrated in FIG. 3 in a
`manner same as the one described above.
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`With this technique, the hight difference significantly
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`disappears from the surface of the SiO? film 14 as shown
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`in FIG. 5D,and the dishing of the SiO?film 14 is also
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`reduced. However, the SiO? film 14 showsslight up-
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`ward bulges in areas of the metal wires 13 to provide
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`small increased and recessed portions that are reversals
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`of those of the SiOz film 14 before the SiO? film 14is
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`polished.
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`The result of an analysis looking into this phenome-
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`non is summarized in FIG. 6. The object of the analysis
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`is a device comprising metal wires 13 have a width of
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`500 wm andarranged with a distance of 1,000 um sepa-
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`rating adjacent wires. The abscissa of the graph of FIG.
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`6 represents the polishing time (seconds)in the process-
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`ing step of FIG. 5D, while the coordinate represents the
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`distance betweenthe surface ofthefirst SiO? film 12 and
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`the that of the second SiO: film 14.
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`Before the start of the operation of polishing the
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`device, the distance (solid line in FIG. 6) between the
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`areas (raised portions) of the surface of the SiO?film 12
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`carrying a metal wire 13 and the surface of the SiOofilm
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`14 and the distance (broken line in FIG. 6) between the
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`areas (recessed portions) of the surface of the SiO212
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`film carrying no metal wire and the surface of the SiO2
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`film 14 show a difference of 1.1 2m whichis equal to the
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`height of the metal wires 13.
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`Asthe polishing operation proceeds, the difference
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`between the distance separating the surface of the SiO2.
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`film 12 and that of the SiOfilm 14 at the raised portions
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`and the corresponding distance at the recessed portions
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`is reduced because the speed at which the SiO>film 14is
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`polished off for the raised portions is greater than the
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`speed at which it is polished off for the recessed por-
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`tions. The reason for the difference in speed is that the
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`SiO} film 14 is subjected to a greater load at the raised
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`portions. Additionally with this technique, the speed at
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`Morespecifically, an Si substrate 1 having a configu-
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`ration as described aboveis set in position on the turnta-
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`ble the apparatus under a holder 501. A polishing slurry
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`feed pipe 503 is disposed above the turntable 502 to feed
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`a polishing slurry onto the truntable during the opera-
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`tion of polishing the substrate. A polishing cloth 504 is
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`disposed between the surface to be polished of the Si
`substrate 1 and the turntable 502 so that the raised and
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`recessed portions on the surface of the semiconductor
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`substrate are removed by particles of the polishing
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`slurry and the polishing cloth 504 to provide a plana-
`rized surface of the semiconductor substrate.
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`The holder 501 is subjected to a load of 40 kfg and
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`rotated at a rate of 100 rpm. Theturntableis rotated at
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`the same rotation speed.
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`While the above described polishing method using a
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`polishing apparatus can significantly reduce the raised
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`portions on the surface of the second SiO?film 14,it also
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`dishes the portions of the second SiO? film 14 that are
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`located between ad