eTTTL
`
`
`
`
`5,592,024
`[11] Patent Number:
`United States Patent 15
`
`
`
`
`
`
`
`Aoyamaetal.
`[45] Date of Patent:
`Jan. 7, 1997
`
`
`
`
`
`
`
`
`
`
`
`
`[75]
`
`
`[54] SEMICONDUCTOR DEVICE HAVING A
`
`
`
`
`
`WIRING LAYER WITH A BARRIER LAYER
`
`
`
`
`
`.
`:
`sas
`Inventors: Hisako Aoyama, Kawasaki; Kyoichi
`
`
`
`
`
`Suguro, Yokohama; Hiromi Niiyama,
`
`
`
`Yokohama; Hitoshi Tamura,
`
`
`
`
`
`Yokohama; Hisataka Hayashi,
`
`Yokohama; Tomonori Aoyama; Gaku
`
`
`
`
`Minamihaba, both of Kawasaki;
`
`
`
`
`Tadashi lijima, Yokohama, all of Japan
`
`
`
`
`
`
`
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`
`0040745 12/1970
`Japan .
`
`
`
`0040515 10/1972
`Japan.
`.
`
`
`
`
`0242331
`10/1987
`Tapan sesnsesenstsnstsetnsessennta 257/760
`
`
`
`
`
`0082653
`3/1989
`Japan ....
`257/760
`
`
`
`
`
`
`Japan ....
`2-78769
`11/1990°
`257/760
`
`
`
`
`
`0270256 12/1991
`257/760
`Japan ....
`
`
`
`
`
`Japan ...essecsessarsessssscssssersesesces 2571760
`12/1993
`0343541
`
`
`
`
`
`OTHER PUBLICATIONS
`
`
`IBMTDB, Lithographic Patterns With a Barrier Liner, vol.
`
`
`
`
`
`
`
`32, No. 103, Mar. 1990, pp. 114-115.
`
`
`
`
`
`
`
`IBMTDB, Coppcr Multilevel Interconnections, vol. 33, No.
`
`
`
`
`
`
`
`
`
`11, Apr. 1991, pp. 299-300.
`
`
`
`
`
`IBMTDB, AG Metallurgy System for Integrated Circuit
`
`
`
`
`
`Devices vol. 13, No. 2, Jul. 1970, pp. 511-512.
`
`
`
`
`
`
`
`
`Filed:
`Oct. 28, 1994
`[22]
`.
`.
`
`
`
`
`
`Primary Examiner—Peter Toby Brown
`
`
`Attorney, Agent, or Firm—Oblon, Spivak, McClelland,
`Foreign Application Priority Data
`[30]
`
`
`
`
`
`
`
`
`
`
`
`
`
`Oct. 29, 1993 Japan enmertnemeenense 5.272784|Maier & Neustadt, PC.[JP]
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Mar. 15,1994
` Japan .... 6-070156
`
`ABSTRACT
`
`[JP]
`[57]
`
`
`
`
`Sep. 19,1994
`Japan oo. sssessessesseseccensnerenes 6-249984
`[JP]
`
`
`
`
`
`
`
`Int. cle dresanesasevconnanserens HOIL 23/535; HOIL 29/41;
`[51]
`
`
`
`
`
`
`HO1L 29/43
`
`
`[52] WS. CU. eessssessssesseeesonees 257/751; 257/752; 257/760;
`
`
`
`
`
`
`
`257/763, 257/764; 257/762; 257/915
`
`
`
`
`
`
`[58] Field of Search ...........scccessenseees 257/750-753,
`
`
`
`
`257/759, 760, 762, 773, 763, 764, 915
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`.
`A semiconductor device comprises a semiconductor sub-
`
`
`
`
`
`
`strate in which a semiconductor element
`is formed, an
`
`
`
`
`
`
`
`
`
`interlayer insulating film formed on the semiconductor sub-
`
`
`
`
`
`
`
`strate, an insulating barrier layer, formed on the interlayer
`
`
`
`
`
`
`
`
`
`insulating film by plasmanitriding, for preventing diffusion
`
`
`
`
`
`
`
`
`of a metal constituting a wiring layer, a conductive barrier
`
`
`
`
`
`
`
`
`
`layer, formed on the insulating barrier layer, for preventing
`
`
`
`
`
`
`
`
`
`
`
`
`diffusion of the metal, and a wiring layer formedof the metal
`
`
`
`
`
`
`
`
`on the conductive barrier layer. A bottom portion of the
`
`
`
`
`
`
`
`
`
`
`
`
`
`wiring layer is protected by the conductive barrier layer and
`
`
`
`
`
`
`
`the insulating barrier layer. Therefore, the diffusion of the
`
`
`
`
`
`
`
`
`
`
`
`
`metal constituting the wiring layer can be surely prevented.
`
`
`
`
`
`
`
`5 Claims, 35 Drawing Sheets
`
`
`
`
`
`
`
`[73] Assignee: Kabushiki Kaisha Toshiba, Kawasaki,
`
`
`
`
`
`
`Japan
`
`
`
`[21] Appl. No.: 330,998
`
`
`
`
`
`
`
`
`
`
`
`
`[56]
`
`
`References Cited
`
`
`U.S. PATENT DOCUMENTS
`
`
`4,091,406
`5/1978 Lewis ...cesseccsesssssssencssnesssesseeens 257/760
`
`
`
`
`
`
`4,789,648 12/1988 Chowet al.
`. 437/225
`
`
`
`
`
`
`
`
`
`
`
`4/1994 Joshi et ab. oossessecsenceseece 257/752
`5,300,813
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 1 of 53
`
`TSMC Exhibit 1018
`
`TSMC Exhibit 1018
`
`Page 1 of 53
`
`

`

`Saooooe 20 3 FIG. 2A PRIOR ART
`
`
`
`U.S. Patent
`Jan. 7, 1997
`
`
`
`
`SE?oe
`
`VTIT As
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`2
`
`1504
`203
`
`
`202
`
`
`201
`
`
`
`
`F1G. 4B PRIOR ART
`
`
`
`203
`
`205
`204
`
`
`
`
`207
`202
`
`
`
`
`Sheet 1 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`205
`
`204
`203
`
`|
`
`
`202
`
`204
`
`
`
`
`
`
`
`FIG. 2B PRIOR ART
`
`
`
`208
`
`
`202
`
`
`201
`
`
`
`F1G.4C PRIOR ART
`
`
`
`FIG. 3A.
`
`
`
`201
`PRIOR ART
`
`
`
`
`
`
`
`
`FIG. 1D PRIOR ART
`
`
`
`
`
`Page 2 of 53
`
`209
`208
`
`
`
`
`202
`
`201
`
`
`
`FIG. 3B PRIOR ART
`
`
`
`
`Page 2 of 53
`
`

`

`
`US. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 2 of 35
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` F 1G. 4B PRIOR ART
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`2ii
`
`
`210
`
`
`
`FIG. 4C PRIOR ART
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG. 5C PRIOR ART
`
`
`
`
`
`
`212 i 2i0
`
`
`
`201
`
`
`225
`
`223
`
`
`
`FIG. 4D PRIOR ART
`
`
`
`
`
`FIG. 5D PRIOR ART
`
`
`
`Page 3 of 53
`
`Page 3 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 3 of 35
`
`
`
`
`
`5,592,024
`
`
`
`SSNS
`PRIOR ART VLLL) oe
`
`
`
`
`FIG. 6A ||ty
`
`
`
`
`
`|
`|
`|
`
`
`
`6B
`
`
`
`PRIOR ART
`
`
`
`FIG.
`
`
`
`
`
`
`
`
`
`
`
`
`
`PRIOR ART
`)
`
`
`FIG.
`6C Ct
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`fy
`
`
`22k
`220
`
`
`
`
`
`PRIOR ART
`
`
`
`6D
`FIG.
`
`
`
`Page 4 of 53
`
`Page 4 of 53
`
`

`

`
`U.S. Patent
`
`
`
`
`
`PRIOR ART
`
`
`
`FIG.
`7A
`
`
`
`
`
`PRIOR ART
`
`
`
`FIG 7B
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 4 of 35
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`407b 405
`407a
`
`
`
`
`
`
`y
`LT
`
`
`
`}—41__1_£\.\N>
`
`
`
`
`
`
`
`
`401
`
`
`
`PRIOR ART
`
`
`
`
`
`Pig. TC
`
`
`
`Qa
`
`408
`
`4080
`405
`
`
`
`
`TU M7
`LY, ~
`Ve Ze
`
`
`
`PRIOR ART9[SSAASS
`
`
`
`FIG 7D
`‘or
`
`
`
`
`
`Page 5 of 53
`
`Page 5 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 5 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`4080
`
`4p,
`
`Va
`
`Pa Mannie
`
`408D
`
`
`
`PRIOR ART
`
`
`
`FIG 7E
`
`FIG 8B
`
`
`
`
`
`PRIOR ART
`
`
`
`
`Page6 of 53
`
`8A
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`PRIOR ART
`
`
`
`FIG. 7F
`
`
`
`PRIOR ART
`
`
`
`FIG.
`
`
`
`
`
`
`
`
`
`
`
`Page 6 of 53
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`409b
`NN)
`
`5,592,024
`
`
`PAE,
`
`Ess
`4™
`
`
`
`[7
`402 ing 404
`401
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet6 of 35
`
`
`
`
`
`
`
`U.S. Patent
`
`
`
`
`
`PRIOR ART
`
`
`
`FIG.
`9A
`
`
`
`PRIOR ART
`
`
`FIG. 9B
`
`
`
`
`
`PRIOR ART
`
`
`
`FIG.
`9C
`
`
`
`
`
`PRIOR ART
`
`
`
`FIG.
`9D
`
`Page 7 of 53
`
`
`
`
`
`
`
`Page 7 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 7 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
` 414
`
`
`413
`
`
`Ate
`ati
`
`
`
`
`23
`
`22
`
`O1
`
`
`414
`
`413
`
`412
`
`Alt
`
`
`
`
`
`
`!
`
`
`4 3 2 8 >
`
`|
`
`24
`
`93
`
`22
`
`Qi
`
`PRIOR ART
`
`
`
`
`
`
`410A
`FIG.
`
`
`
`
`
`PRIOR ART
`
`
`
`
`10B
`FIG.
`
`
`
`FIG.
`
`
`12
`
`
`
`FIG 414A
`
`
`
`
`
`FIG. 148
`
`
`
`
`
`Page 8 of 53
`
`Page 8 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 8 of 35
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`4 3 2 {
`
`4 3
`
`2 {
`
`
`
`FIG.
`
`
`441A
`
`
`
`
`
`
`FIG 418
`
`
`
`
`
`
`
`
`
`
`3 2
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 9 of 53
`
`
`
`
`
`
`
`
`
`Page 9 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan.7,1997
`
`
`
`Sheet 9 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`SS oS
`AN,
`sabenA
`
`VLISVLL
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 10 of 53
`
`Page 10 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 10 of 35
`
`
`
`
`
`5,592,024
`
`
`
`
`
`is
`‘a
`40
`
`43.
`
`
`41
`
`WwW/Yess
`
`
`
`INXTXONio
`16 gq 18b
`i
`
`FIG.
`47
`
`e 42
`ph. 49
`
`oT”
`
`
`
`
`
`
`
`
`
`
`
`FIG.
`
`
`
`
`
`188
`
`
`45
`
`
`43
`
`44
`:
`
`
`
`
`
`48
`Be
`
`
`
`
`FIG. 19A
`
`44
`
`
`
`
`FIG. 19B
`
`FIG i48C
`
`
`
`
`
`
`Page 11 of 53
`
`Page 11 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 11 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` FIG. 20C
`
`
`
`
`
`
`
`
`
`
`65
`
`?
`
`
`66
`
`
`64
`
`63
`
`62
`
`
`6!
`
`
`
`FIG. 20D
`
`Page 12 of 53
`
`Page 12 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 12 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`:
`
`
`
`FIG 214A
`
`
`
`t
`cH
`\
`
`L2EITH:
`
`
`14
`
`73
`
`7
`
`
`FIG 21C
`
`
`
`
`
`
`
`
`
`FIG.
`
`
`2418
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG. 24D
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`15
`78
`a 78
`
`
`
`
`
`; po
`
`
` ne oe CZZZ Te
`
`
`
`
`
`Page 13 of 53
`
`Page 13 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 13 of 35
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
` FIG 22E
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 14 of 53 |
`
`Page 14 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 14 of 35
`
`
`
`
`
`5,592,024
`
`
`
`95
`\
`
`PITAPPh
`9 2PFFEEIS93
`
`9493
`
`94
`
`
`
`
`92
`91
`
`
`
`
`
`FIG. 23A
`
`
`
`
`
`
`FIG. 23B
`
`
`
`
`
`
`
`
`
`
`
`FIG.
`
`23D
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` FIG. 23C
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG. 23E
`
`
`
`Page 15 of 53
`
`Page 15 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 15 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` FIG. 24A
` FIG. 248
`FIG. rac
` FIG. 24D
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`‘96
`
`" 109
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`[ZASSSZZSMZ
`77SPWEA
`
`
`
`
`FIG. 24E
`
`Page 16 of 53
`
`
`
`
`
`
`
`
`
`
`
`
`Page 16 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan.7, 1997
`
`
`
`
`
`Sheet 16 of 35
`
`
`
`
`
`123
`
`S124
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`254A
`
`
`
`
`25C
`
`258
`
`124
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG.
`
`
`
`
`
`
`
`
`
`
`
`FIG.
`
`Page 17 of 53
`
`
`123
`
`“8 30
`129 134 139
`
`
`
`
`
`
`{26
`(] Anhewantanmhcervuhaubanfel /|
`aaaa
`
`CIELAIT1285
`
`
`CaaNa=
`
`SY 124
`
`25D SES 124
`
`
`134 ee
`
`ESA Be
`133
`
`
`132
`
`
`
`
`U/LSLYHE
`QS 124
`
`
`
`24
`
`
`
`
`25E
`
`
`
`129
`
`
`
`
`
`
`
`
`
`
`Page 17 of 53
`
`

`

`U.S. Patent
`
`
`
`
`Jan. 7, 1997 Sheet 17 of 35
`
`
`
`
`
`
`
`Ss
`
`
`
`
`
`5,592,024
`
`
`
`
`
`FIG. 26A
`
`
`FIG. 26B
`
`
`
`147
`
`
`
`143 144
`
`
`
`
`4
`
`
`
`
`145
`142°
`144
`
`
`
`
`
`
`148 144
`148 y44
`
`
`
`ZVALZVIZLZACNS
`
`
`
`4SfLfAWAA“
`
`
`
`
`
`
`FIG. 26C Lp
`y 192 144
`148
`
`(ZZRAYZZLZLF has
`
`
`SACAIEAL
`
`
`
`
`
`
`
`
`
`FIG. 26D
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG. 26E
`
`
`
`Page 18 of 53
`
`
`
`Page 18 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 18 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`27C¢
`
`
`
`
`FIG 27A
`
`
`
`
`FIG 278
`
`
`
`
`
`
`
`FIG.
`
`Page 19 of 53
`
`Page 19 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 19 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`27D
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` FIG.
`
`27F
`
`
`
`
`
`FIG.
`
`
`
`
`
`Page 20 of 53
`
`Page 20 of 53
`
`

`

`
`
`US. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 20 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`FIG.
`
`
`
`
`
`
`
`
`
`
`
`
`
`waa4
`
`
`
`2VZA
`
`276, an
`FIG 27H
`RARSSISSs
`
`
`
`
`
`
`
`
`
`
`FIG. 27]
`
`Page 21 of 53
`
`SVSVALS0%/| 307
`
`
`
`
`
`
`
`
`
`
`306
`
`
`
`
`304
`
`Page 21 of 53
`
`

`

`
`US. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 21 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`343b
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`315b FIG 28
`308SsLNpo
` FIG. 284sake
`
`FIG. 29B
`
`
`
`sfoa.
`34sa 31i5bD=314
`
`
`
`
`
`
`
`b|
`
`
`
`
`
`
`LLL/ L
`J
`
`ASSLLL
`
`
`
`
`
`
`
`Page 22 of 53
`
`Page 22 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 22 of 35
`
`
`
`
`
`5,592,024
`
`
`
`FIG 341A
`
`FIG 31B
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`507
`
`
`5070
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 23 of 53
`
`Page 23 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 23 of 35
`
`
`
`
`
`5,592,024
`
`
`
`
`507
`OLLLRE
`Seegpa| St-503
`
`FIG 31E
`S//)¥ 2)}—41 501
`
`
`
`
`
`
`
`
`
`IS
`
`506
`
`FIG 3iF(444£
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` oe
`
`
`
`
`
`
`
`
`
`Page 24 of 53
`
`
`
`
`
`Page 24 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 24 of 35
`
`
`
`
`
`5,592,024
`
`
`
`FIG 31H
`FIG 34d
`
`
`
`
`
`
`
`
`
`FIG. 31]
`
`
`
`
`
`
`
`
`
`
`Page 25 of 53
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`A i
`
`
`
`
`
`
`
`
`Page 25 of 53
`
`

`

`U.S. Patent
`
`
`
`
`jan. 7,197
`
`
`
`
`Sheet 250035
`
`
`
`
`
`
`
`
`
`~—-Ss«#S592,024
`
`
`
`
`X15
`
`
`514
`
`S15
`
`
`544
`
`
`
`
`
`FIG 31K
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG.
`
`Page 26 of 53
`
`
`
`DEY——SSS
`
` 3SdL
`
`
`E24pl
`AA
`
`
`
`
`
`
`
`315
`
`
`
`
`39544
`
`
`
`514
`
`arreree_—
`
`eS
`|_——
`
`506
`
`Page 26 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 26 of 35
`
`
`
`
`
` §,592,024
`
`
`
`
`
`
`
`
`
`
`FIG. 30
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`300.0
`
`
`
`
`400.0
`
`
`
`
`
`500.0
`
`rlwhaADNDOOD.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`200.0
`
`
`
`0.0
`
`
`
`100.0
`
`
`—
`
`
`
`FIG. 32
`
`
`
`Page 27 of 53
`
`Page 27 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 27 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` FIG 33A
`
`
`A VAG
`LLLLL,
`
`
`
`
`
`
`FIG 338
`
`SD,ED,,C,,,,” 603
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 28 of 53
`
`Page 28 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`Sheet 28 of 35
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG 33D
`
`FIG. 33E/ FIG 33F
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 29 of 53
`
`Page 29 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 29 of 35
`
`
`
`
`
`5,592,024
`
`
`
`FIG. 336
`
`
`
`
`
`
`
`
`|
`
`
`
`
`
`
`
`
`
`|
`
`|
`
`{Nn
`
`
`
`
`
`
`615
`
`614
`
`
`
`
`607
`
`
`610wwFIG 33H
`
`615
`QQ
`
`
`SZ PAP ei
`
`
`ff
`|
`
`FIG. 331BAP
`issU/LALF
`ONS
`
`
`W777,
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`|
`
`
`
`
`
`
`
`
`
`Page 30 of 53
`
`Page 30 of 53
`
`

`

`
`US. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 30 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`FIG.
`
`34A
`
`
`
`
`
`
`
`
`701
`
`
`
`
`
`
`
`
`FIG. 348
`
`o
`
`
`
`FIG.
`
`
`
`34C
`
`
`
`
`
`
`
`
`
`Page 31 of 53
`
`FIG. 34D
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 31 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`
`Sheet 31 of 35
`
`
`
`
`
`5,592,024
`
`
`
`
`
`
`
`
`
`FIG 34E
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 32 of 53
`
`Page 32 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan.7, 1997
`
`
`
`
`Sheet 32 of 35
`
`
`
`
`
`5,592,024
`
`
`
`S| 824
`
`TE OS
`CF 4-02
`820
`
`
`823
`829 gig
`
`9824
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`828
`
`
`824
`
`
`823
`
`
`820
`
`
`
`
`
`Page 33 of 53
`
`Page 33 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`
`Sheet 33 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`| $824
`823OL
`
`uea.he Q
`
`
`
`823
`
`822
`
`—_—
`
`
`
`
`
`FIG 36
`
`
`
`Page 34 of 53
`
`Page 34 of 53
`
`

`

`
`U.S. Patent
`
`
`
`Jan. 7, 1997
`
`
`
`Sheet 34 of 35
`
`
`
`
`
`5,592,024
`
`
`
`905
`
`906
`904
`
`903
`
`
`
`902
`
`
`
`901
`
`
`
`
`
`
`FIG 37A
`
` FIG. 37B
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`906
`904
`
`907
`
`
`
`906
`905
`
`903
`
`902
`
`
`
`a
`
`FIG. 37C
`
`
`
`
`
`
`37D
`
`
`
`
`
`
`
`
`
`
`
`FIG.
`
`
`
`Page 35 of 53
`
`Page 35 of 53
`
`

`

`
`U.S. Patent
`
`
`
`
`
`Jan. 7, 1997
`
`
`
`Sheet 35 of 35
`
`
`
`
`
`
`5,592,024
`
`
`
`1005 1003
`1004
`
`
`
`1004
`
`1003
`
`1002
`
`
`100{
`
`1002
`
`i001
`
`
`
`
`
`FIG. 38A
`
`
`
`
`
`
`FIG. 38B
`
`
`
` NS
`way,LLTLS
`1003 /
`
`
`
`LfLf:
`
`
`
`
`
`
`FIG.
`38C
`
`1005
`
`1004
`
` S
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIG. 38D
`
`Page 36 of 53
`
`Page 36 of 53
`
`

`

`
`2
`
`
`
`side walls of the wiring portion are not coated with the
`
`
`
`
`
`
`
`
`
`
`barrier metal layer 207. Thus, the oxidation and diffusion of
`
`
`
`
`
`
`
`
`
`the wiring material cannot be prevented.
`
`
`
`
`
`
`
`FIGS.3A and 3B are cross-sectional views showing steps
`
`
`
`
`
`
`BACKGROUND OF THE INVENTION
`
`
`
`
`
`
`of another conventional wiring forming process.
`
`
`
`Atfirst, as shown in FIG. 3A, wiring 208 madeofan alloy
`
`
`
`
`
`
`
`
`
`
`
`
`
`1. Field of the Invention
`
`
`
`
`
`
`
`of a wiring material and a material tending to be oxidized or
`
`
`
`
`
`
`
`
`
`
`The present invention relates to techniques of buried
`
`
`
`
`
`
`
`
`
`nitrided more easily than the wiring material is formed on a
`
`
`
`
`
`
`
`
`wiring in semiconductor technology.
`
`
`semiconductor substrate 201 on which an interlayer insu-
`
`
`
`
`
`
`
`
`
`
`
`
`2. Description of the Related Art
`
`
`
`
`
`
`lating film 202 is provided.
`
`
`Then, the structure shown in FIG. 3A is annealed in an
`With higher operation speed and higher integration den-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`sity, wiring has become thinner and more multilayered.
`atmosphere including a slight quantity of oxygen or nitro-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`gen. Asa result, as shown in FIG. 3B, the above-mentioned
`
`
`Since thinning of wiring results in an increase in resistance
`
`
`
`
`
`
`
`
`
`
`
`
`material tending to be oxidized or nitrided more easily is
`
`
`
`
`
`
`
`
`
`
`
`
`
`and a decrease in reliability,
`it is required to use low-
`
`
`
`
`
`
`diffused to the surfaces of the wiring 208, and an oxide film
`
`
`
`
`
`
`
`
`
`
`
`
`resistance, high-reliability wiring materials such as Au, Ag,
`
`
`
`
`
`
`
`
`
`and Cu.
`
`or a nitride film 209 is formed onthe entire periphery of the
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`wiring 208. Since the oxide film or nitride film 209 is
`
`
`
`
`
`
`
`Such materials, however, have problems with respect to
`
`
`
`
`
`
`
`
`formed,
`the impurity concentration in the wiring 208
`
`
`
`
`
`
`
`
`
`
`adhesion to an interlayer insulating film, diffusion into the
`
`
`
`
`
`
`
`decreases and the interior of the wiring 208 has properties
`
`
`
`
`
`
`
`
`
`
`interlayer insulating film, oxidation and agglomeration,as
`
`
`
`
`
`
`
`
`
`
`similar to a pure metal.
`
`
`
`
`
`compared to conventional Al-based materials.
`
`
`
`This process, however, has the following problems. High-
`
`
`
`
`
`
`
`
`
`In order to solve these problems, when this kind of
`
`
`
`
`
`
`
`
`
`
`
`
`temperature heattreatmentis required to form the oxide film
`
`
`
`
`
`
`
`
`
`
`material is used, the periphery of wiring is coated with a film
`
`
`
`
`
`
`
`
`
`
`
`or nitride film 209. Becauseofthis, transistor characteristics
`
`
`
`
`of a material different from the material of the wiring. This
`
`
`
`
`
`
`
`
`
`
`
`are adversely effected. For example, the depth of a junction
`
`
`
`
`
`
`
`
`
`
`
`kind. of wiring is formed, for example, by a process illus-
`
`
`
`
`
`
`
`increases. Moreover, since an intergranular diffusion is
`
`
`
`
`
`
`trated in FIGS. 1A to 1D.
`
`
`
`
`
`
`
`
`dominant with respectto the diffusion,it is difficult to coat
`
`
`
`
`
`
`
`
`
`
`
`
`the wiring 208 uniformly with the oxide film ornitride film
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Asis shown in FIG. 1A,atfirst, a semiconductor substrate
`
`
`
`
`
`
`209. These problems lead to degradation in reliability.
`
`
`
`
`
`
`
`
`201, on the surface of which an interlayer insulating film 202
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`FIGS. 4A to 4D are cross-sectional views showing steps
`
`
`
`
`
`is formed, is prepared. A barrier metal layer 203, having
`
`
`
`
`
`
`
`
`
`
`
`of another conventional wiring forming process.
`
`
`
`
`
`effects in preventing diffusion of material wiring and
`
`
`
`
`
`
`
`
`enhancing adhesion, is formed on the interlayer insulating
`
`
`
`
`As is shown in FIG. 4A,an interlayer insulating film 202
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`film 202 by means of vapor deposition or sputtering. A
`
`having a wiring groovein a surface portion thereof is formed
`
`
`
`
`
`
`
`
`
`
`on a semiconductor substrate 201.
`
`
`
`
`
`
`
`conductor 204, which will become wiring, is formed on the
`
`
`
`
`
`
`
`
`barrier metal layer 203. A barrier metal layer 205 having the
`
`
`
`
`
`
`
`
`
`
`
`
`
`A diffusion prevention layer 210 is formed on the entire
`
`
`
`
`
`
`
`
`
`
`
`same effects as the barrier metal layer 203 is formed on the
`
`
`
`
`
`
`
`
`
`
`
`
`structure, as shown in FIG. 4B, thereby to prevent a wiring
`
`
`
`
`
`
`conductor film 204. A resist is coated on the barrier metal
`
`
`
`
`
`
`
`
`
`
`
`
`
`material from diffusing into the interlayer insulating film
`
`
`
`
`
`
`
`
`
`
`layer 205, exposed, and developed, thereby formingaresist
`
`
`
`
`
`
`202. Subsequently, a conductor layer 211 which will become
`
`
`
`
`
`
`
`
`
`
`
`pattern 206 for forming wiring.
`
`
`
`
`
`a buried wiring portion is formed onthe entire structure. The
`
`
`
`
`
`
`
`
`
`
`material of the diffusion prevention film 210 is, for example,
`
`
`
`
`
`
`
`
`Then, as shown in FIG. 1B, with the resist pattern 206
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`a material tending to be oxidized or nitrided moreeasily than
`
`
`
`
`
`
`
`
`
`used as a mask, the barrier metal layer 205, conductor film
`
`
`
`
`
`
`
`
`
`
`the wiring material.
`
`
`
`
`204 and barrier metal layer 203 are etched in a shape of
`
`
`
`
`
`
`
`
`
`
`wiring.
`
`
`
`
`Then, as shown in FIG. 4C, the entire surface of the
`
`
`
`
`
`
`
`resultant structure is etched so as to leave the conductor film
`
`
`
`
`
`
`
`
`
`
`
`Subsequently, as shown in FIG. 1C,a barrier metal layer
`
`
`
`
`
`
`
`
`
`
`
`
`211 only in the wiring groove,
`thus forming the buried
`
`
`
`
`
`
`
`
`
`207, whichis different from the wiring 204 and has the same
`
`
`
`
`
`
`
`
`
`
`
`
`wiring portion 211.
`
`
`
`
`
`effects as the barrier metal layer 203, is formed on theentire
`
`
`
`
`
`
`
`
`
`
`
`resultant structure, thereby covering side walls ofthe wiring
`
`
`
`
`
`
`
`
`
`
`
`
`
`Lastly, as shown in FIG. 4D, the resultant structure is
`
`
`
`
`portion.
`
`
`
`annealed in an atmosphere including a slight amount of
`
`
`
`
`
`
`
`
`
`
`oxygenor nitrogen, and diffusion is effected in a region from
`
`
`
`
`
`
`
`
`
`
`Lastly, as shown in FIG. 1D,the barrier metal layer 207
`
`
`
`
`
`
`
`
`
`
`the diffusion prevention film 210 up to the surface of the
`
`
`
`
`
`
`
`is anisotropically etched,
`thereby selectively leaving the
`
`
`
`
`
`
`
`
`
`
`buried wiring portion 211. Thus, an oxidefilm ornitride film
`
`
`
`
`
`
`
`
`
`
`barrier metal layer 207 on the side walls of the wiring
`
`
`
`
`
`
`
`
`
`
`
`
`
`212is formedin a surface portion of the buried wiring 211.
`
`
`
`
`
`
`
`portion.
`
`
`
`Accordingto this method, since the surface of the wiring
`
`
`
`
`
`
`
`
`
`
`According to this process, since the wiring structure
`
`
`
`
`
`
`
`211 can be coated with the oxide film ornitride film 212 in
`
`
`
`wherein the outer surfaces of the conductor film 204 or
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`a self-alignment manner,
`the number of steps
`is not
`
`
`
`
`
`
`
`
`wiring body is coated with barrier metal layers 203, 205 and
`
`
`
`
`
`
`
`
`
`
`increased.
`
`
`
`207 is obtained, oxidation and diffusion of the wiring
`
`
`
`
`
`
`
`
`
`
`
`material can be prevented.
`
`
`
`However, since the intergranular diffusion is dominant
`
`
`
`
`
`
`
`with respect to the diffusion, the oxide film or nitride film
`
`
`
`
`
`
`
`
`This process, however; has the following problems: the
`
`
`
`
`
`
`
`
`
`
`
`212 is not formed uniformly although the conductorfilm 211
`
`
`
`
`
`
`
`
`numberofsteps is large, and the insulating film provided on
`
`
`
`
`
`
`
`
`
`
`
`
`is not alloyed. Therefore, there is a problem in reliability.
`
`
`
`
`
`
`
`
`
`
`
`
`the wiring must be flattened, and thus this process is not
`
`
`
`
`
`
`
`
`
`
`suitable for multilayer structure.
`
`
`
`
`
`In addition, like the process illustrated in FIGS. 3A and
`
`
`
`
`
`
`
`3B, high-temperature heat treatment is required to form the
`
`
`
`
`
`
`
`
`If the wiring portion obtained in the step shown in FIG.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`oxide film or nitride film 212. The high-temperature heat
`
`
`
`
`1B is formed in a tapered shape, the barrier metal layer 207
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`treatment adversely affects transistor characteristics and
`
`
`
`
`
`
`may not be formed on the side walls of the wiring portion,
`
`
`
`
`
`
`
`
`
`
`requires completeness of the diffusion prevention film 210.
`
`
`
`
`
`
`
`
`as shown in FIG. 2A,or the conductor film 207 on the side
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`walls of the wiring portion may be etchedat the time ofthe
`
`
`
`
`
`
`
`
`
`
`
`Furthermore, since the width of the wiring 211 is
`
`
`
`
`
`
`
`
`anisotropic etching, as shown in FIG.2B, and,as a result, the
`
`
`
`
`
`
`
`
`
`
`
`
`decreased by the degree correspondingto the presenceofthe
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`10
`
`
`
`15
`
`
`
`20
`
`
`25
`
`
`
`30
`
`
`
`
`
`40
`
`
`45
`
`
`
`
`55
`
`
`
`
`
`65
`
`
`
`1
`SEMICONDUCTOR DEVICE HAVING A
`
`
`
`
`WIRING LAYER WITH A BARRIER LAYER
`
`
`
`
`
`
`
`
`5,592,024
`
`
`
`
`
`Page 37 of 53
`
`Page 37 of 53
`
`

`

`
`
`5,592,024
`
`
`
`
`3
`
`
`
`
`
`
`
`the wiring resistance
`diffusion prevention film 210,
`
`
`
`
`
`
`
`
`
`increases. If the width of the wiring groove is enlarged, the
`
`
`
`
`
`
`
`
`
`
`problem of wiring resistance does not occur. However,
`
`
`
`
`
`
`
`
`
`
`
`because of the increase in width of the wiring groove, the
`
`
`
`
`
`wiring cannot be thinned effectively.
`
`
`
`
`
`
`
`FIGS. 5A to 5D are cross-sectional views showing steps
`
`
`
`
`
`
`
`
`
`
`of a process for forming a through-hole in buried wiring. A
`
`
`
`
`
`
`
`
`
`
`
`
`wiring groove and a through-hole are formed in this order.
`
`
`
`
`
`
`
`
`
`
`In this invention, “through-hole” refers to a via hole for
`
`
`
`
`
`
`
`
`
`connection between wiring layers or a contact hole for
`
`
`
`
`
`
`
`
`connection between a wiring layer and a semiconductor
`substrate.
`
`
`
`
`
`
`
`
`
`
`
`
`Atfirst, as shown in FIG. SA,a first interlayer insulating
`
`
`
`
`
`
`
`
`film 221 and a second interlayer insulating film 222 are
`
`
`formed on the semiconductor substrate 220 in this order.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Then, a wiring groove 223is formed in the secondinterlayer
`
`
`
`insulating film 222.
`
`
`
`
`
`
`
`
`
`
`Subsequently, as shown in FIG. 5B, a resist pattern 224
`
`
`
`
`
`
`
`
`
`
`for forming the through-hole is provided. In this case, the
`
`
`
`
`
`
`
`
`
`
`resist pattern 224 is displaced to the right owing to mis-
`
`alignment.
`
`
`
`
`
`
`
`
`
`
`
`the first
`With the resist pattern 224 used as a mask,
`
`
`
`
`
`
`
`
`
`interlayer insulating film 221 is etched to form a through-
`
`
`
`
`
`
`
`hole 225, as shown in FIG. 5C.
`
`
`
`
`
`
`
`
`
`Since the resist pattern 224 is displaced a predetermined
`
`
`
`
`
`
`
`
`
`portion of the first interlayer insulating film 221 remains
`
`
`
`
`
`
`
`
`unetched while a non-predetermined portion of the second
`
`
`
`
`
`
`interlayer insulating film 222 is etched.
`
`
`
`
`
`
`
`
`
`
`
`Thus, as shown in FIG. 5D,a contactarea of the through-
`
`
`
`
`
`
`
`
`hole 225 decreases by a degree corresponding to displace-
`
`
`
`
`
`
`
`
`
`
`
`
`ment of the resist pattern 224, and the width of the wiring
`
`
`
`
`
`
`
`groove 223 increases at the through-hole 225.
`
`
`
`
`
`
`
`
`The decrease in contactarea ofthe through-hole 225 leads
`
`
`
`
`
`
`
`
`
`to an increase in contact resistance and a degradation in
`
`
`
`
`
`
`
`
`shape of a contact electrodeat the through-hole, resulting in
`
`
`
`
`
`
`
`
`degradationin reliability. On the other hand, the increase in
`
`
`
`
`
`
`
`
`
`width of the wiring prevents an increase in integration
`
`density.
`
`
`
`
`
`
`
`FIGS. 6A to 6D are cross-sectional views showing steps
`
`
`
`
`
`
`
`
`
`
`of another process for forming a through-hole in buried
`
`
`
`
`
`
`
`
`
`
`
`
`wiring. In this process, a through-hole is formed prior to a
`
`
`wiring groove.
`
`
`
`
`
`
`
`
`
`
`
`Atfirst, as shown in FIG. 6A,a first interlayer insulating
`
`
`
`
`
`
`
`film 221 and a second interlayer insulating layer 222 are
`
`
`
`
`
`
`
`
`
`
`
`
`formed in this order on a semiconductor substrate 220, and
`
`
`
`
`
`
`
`that portion of the second interlayer insulating film 222,
`
`
`
`
`
`
`
`
`
`
`where the through-hole will be formed, is etched.
`
`
`
`
`
`
`
`
`
`
`A resist pattern 226 for forming a wiring groove is
`
`
`
`
`
`
`
`
`
`
`
`
`provided onthe entire structure, as shownin FIG.6B. In this
`
`
`
`
`
`
`
`
`
`
`
`
`case, the resist pattern 226 is displaced to the right owing to
`
`misalignment.
`
`
`
`
`
`
`
`
`
`
`With the resist pattern 226 used as a mask,thefirst and
`
`
`
`
`
`
`
`
`
`
`
`second interlayer insulating films 221 and 222 are etched.
`
`
`
`
`
`
`
`
`Thereby, a wiring groove 223 and a through-hole 225 are
`
`
`
`
`simultaneously formed.
`
`
`
`
`
`
`
`
`
`Since the resist pattern 226 is displaced, that portion ofthe
`
`
`
`
`
`
`
`
`
`
`
`first interlayer insulating film 221, at which the through-hole
`
`
`
`
`
`
`should be formed, is not etched.
`
`
`
`
`
`
`
`
`
`the contact area of the
`Like the preceding process,
`
`
`
`
`
`
`
`
`
`through-hole 225 decreases, as shown in FIG. 6D, and the
`
`
`
`
`
`
`
`
`
`
`width of the wiring groove 223 increasesat the through-hole
`
`
`
`
`
`
`
`
`225. Consequently, the same problem as mentioned above
`
`occurs.
`
`
`
`
`
`
`
`
`FIGS. 7A to 7F are cross-sectional views showing steps of
`
`
`
`
`
`
`
`
`
`
`
`
`
`a conventional wiring forming process in the case where an
`
`
`
`
`
`underlayer includes a stepped portion.
`
`
`
`
`
`
`
`
`
`10
`
`
`
`15
`
`
`20
`
`
`
`25
`
`
`30
`
`
`
`35
`
`
`
`40
`
`
`
`45
`
`
`
`50
`
`
`
`55
`
`
`
`60
`
`
`
`65
`
`
`Page 38 of 53
`
`
`4
`
`
`Atfirst, as is shown in FIG. 7A,a field oxide film 402 is
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`formed on a semiconductor substrate 401. Then, a gate oxide
`
`
`
`
`
`
`
`
`
`
`
`film 404, a gate electrode 405 and a diffusion layer 403 are
`
`
`
`
`
`
`
`
`formed. Thereafter, an interlayer insulating film 406 is
`formed on the entire structure.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`By means of a CMP methodor an etch-back method, the
`
`
`
`
`
`
`
`
`
`surface of the interlayer insulating film 406 is flattened.
`
`
`
`
`
`
`
`
`Subsequently, as shown in FIG. 7C, through-holes 407a
`
`
`
`
`
`
`
`
`
`
`and 407are formed by means of photolithography. In this
`
`
`
`
`
`
`
`
`
`case, the depth of the through-hole 407) formed in the
`
`
`
`
`
`
`
`
`
`
`
`
`region of the gate electrode 405 is less than the through-hole
`
`
`
`
`
`
`
`
`
`
`407a formed in the region of the diffusion layer 403 by a
`
`
`
`
`
`
`
`
`
`
`
`
`degree correspondingto the total thickness ofthe field oxide
`
`
`
`
`
`
`
`
`
`
`film 402, gate oxide film 404 and gate electrode 405.
`
`
`
`
`
`
`
`
`
`
`
`In the next step shown in FIG. 7D, contact layers 408a
`
`
`
`
`
`
`
`
`
`
`and 4085 made of a metal such as W are selectively formed
`
`
`
`
`
`
`
`
`
`
`in the through-holes by means of selective CVD method so
`
`
`
`
`
`
`
`
`
`
`that the deeper through-hole may befilled with the contact
`
`
`
`
`
`
`
`
`
`
`
`layer 408a.In this case, the contact layer 408b formedin the
`
`
`
`
`
`
`
`
`shallower through-hole is overfilled from the through-hole.
`
`
`
`
`
`
`
`
`
`The contactlayer 408d overfilled from the through-hole is
`
`
`
`
`
`
`
`
`
`
`etched away, as shown in FIG. 7E, thereby flattening the
`
`
`
`contact layer 408b.
`
`
`
`
`
`
`
`
`
`
`
`Lastly, as shown in FIG. 7F, wirings 409a and 409b are
`
`
`
`
`
`
`
`
`formed on the contact layers 408a and 408b.
`
`
`
`
`
`
`
`
`This wiring forming process, however, as the problem.
`
`
`
`
`
`
`
`
`
`Since the contactlayers buried in the through-holesdiffer
`
`
`
`
`
`
`
`
`
`
`in thickness, the contact layers in the through-holesdiffer in
`
`
`
`
`
`
`resistance and reliability. Moreover, a stepped portion is
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`created by the wirings 409a and 409d andtheflatness of the
`surface is not obtained.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`If the contact layers 408a and 408) are formed so that the
`
`
`
`
`
`
`
`shallower through-hole may be filled with the contact layer
`
`
`
`
`
`
`
`
`
`
`
`
`
`408b, as shown in FIG. 8A, a stepped portion is created in
`
`
`
`
`
`
`
`
`
`
`
`the deeper through-hole. If wiring is formed in thisstate,
`
`
`
`
`
`
`
`
`
`
`unevenness appears in the surface of the wiring formed in
`
`
`
`
`
`
`
`
`the deeper through-hole, as shown in FIG. 8B.
`
`
`
`
`
`
`
`
`
`Whetherthe contact layers are formed so that the deeper
`
`
`
`
`
`
`
`
`through-hole may be filled or the shallower through-hole
`
`
`
`
`
`
`
`
`
`
`may befilled, surface unevenness occurs and it becomes
`
`
`
`
`
`
`
`
`
`difficult to flatten an interlayer insulating film to be formed
`
`
`
`
`
`in a later step.
`
`
`
`
`
`
`
`
`FIGS. 9A to 9D are cross-sectional views showing steps
`
`
`
`
`
`
`
`
`of another conventional wiring forming process in the case
`
`
`
`
`
`
`
`where an underlayer includes a stepped portion.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Atfirst, as is shown in FIG.9A,a field oxide film 402 is
`
`
`
`
`
`
`
`
`formed on a semiconductor substrate 401. Then, a diffusion
`
`
`
`
`
`
`
`
`
`
`
`layer 403, a gate oxide film 404, a gate electrode 405 and an
`
`
`
`
`
`
`interlayer insulating film 406 are formed.
`
`
`
`
`
`
`
`
`
`In the next step shown in FIG. 9B, through-holes 407a
`
`
`
`
`
`
`
`
`
`
`
`and 407b are formed on the diffusion layer 403 and gate
`
`
`
`
`
`
`
`
`
`electrode 405. In this case, since the interlayer insulating
`
`
`
`
`
`film 406 is not flattened, the two through-holes 407a and
`
`
`
`
`
`
`
`
`
`
`
`407b are equal in size.
`:
`
`
`
`
`
`
`
`
`
`
`As is shown in FIG. 9C, a metal is selectively deposited
`
`
`
`
`
`
`
`
`in the through-holes,
`for example, by selective CVD,
`
`
`
`
`
`
`
`
`thereby forming contact layers 408a and 408D.
`
`
`
`
`
`
`
`
`
`Wiring portions 409a and 409d are formed on the contact
`
`
`
`
`
`
`
`
`
`layers 408a and 408b, as shown in FIG. 9D.
`
`
`
`
`
`
`According to this process, since the through-holes 407a
`
`
`
`
`
`and 407b are equal
`in depth,
`the contact layers in the
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`through-holes are equal in resistance and reliability at any
`
`
`
`portions.
`
`
`
`
`
`
`
`
`However, since the interlayer insulating film 406 is not
`
`
`
`
`
`
`
`
`
`
`
`flattened, a focus error, etc. occurs at the time of forming a
`
`
`
`
`
`
`
`
`Page 38 of 53
`
`

`

`5,592,024
`
`
`
`
`5
`
`6
`
`
`
`resist pattern for formingthe wiring portions 409a and 409.
`
`
`
`
`
`
`
`
`
`
`
`
`On the other hand, in the case of the latter, since the
`
`
`
`
`
`
`
`
`
`It is thus difficult to form wirings 409a and 409b of desired
`
`
`
`
`
`
`
`
`
`
`
`
`wiring can be coatedin a self-alignment manner, the number
`
`
`
`
`
`
`dimensions.
`
`
`
`
`of steps does not increase. However, high-temperature heat
`
`
`
`
`
`
`
`Furthermore, since the wiring portions 409a and 409d are