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`Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1022
`Exhibit 1022, Page 1
`
`

`

`
`
`US 6,911,351 B2
`
`
`Page 2
`
`
`
`
`
`U.S. PATENT DOCUMENTS
`
`
`Moriet al.
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`
`Edmondetal.
`
`Saito et al.
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`Wangetal.
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`
`Kiyoku et al. wo... 117/95
`Sasanumaetal.
`
`
`Tsuda et al.
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`
`Kneisslet al.
`
`
`Davis et al. eee 257/76
`
`
`
`
`
`
`Kong et al. wn. 439/589
`Takeuchietal.
`
`
`Althausetal.
`
`
`
`4/1997
`
`
`5,625,637
`4/1998
`
`
`5,739,554
`10/1999
`
`
`5,972,730
`4/2000
`
`
`6,046,465
`11/2000
`
`
`6,153,010
`6/2001
`
`
`6,252,894
`1/2002
`
`
`6,335,546
`9/2002
`
`
`6,448,102
`8/2003
`
`
`6,608,327
`7/2004
`
`
`6,764,932
`2001/0010372
`8/2001
`
`
`10/2001
`2001/0026658
`
`
`FOREIGN PATENT DOCUMENTS
`
`
`62282474 A
`
`02214182 A
`
`11068256 A
`
`11251631
`
`11312825
`
`
`A Eo
`
`
`Al
`
`
`
`
`
`
`
`
`
`
`
`5/1986
`
`2/1989
`
`8/1997
`
`9/1999
`
`11/1999
`
`
`
`
`
`
`
`JP
`JP
`
`
`
`
`2002-518826
`2000-106455
`
`
`
`
`12/1999
`4/2000
`
`
`
`
`
`
`
`OTHER PUBLICATIONS
`
`
`
`
`
`
`
`
`
`I. Kim et al., “Crystal tilting in GaN grown by pendeopitaxy
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`
`
`
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`method on sapphire substrate”, Applied Physics Letters,vol.
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`
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`
`75, No. 26, pp. 4109-4111, Dec. 27, 1999.
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`A.Sakai, “Transmission electron microscopy of defects in
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`Physics Letters, vol. 73, No. 4, pp. 481-483, Jul. 27, 1998.
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`
`
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`H. Sone et al., “Optical and Crystalline Properties of Epi-
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`taxial-Lateral-Overgrown—GaN Using Tungsten Mask by
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`Hydride Vapor Phase Epitaxy”, Jpn. J. Appl. Phys. vol. 38
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`
`
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`(1999), Part 2, No. 4A, pp. L356-L359, Apr. 1, 1999.
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`
`
`
`Tsvetanka et al., “Pendeo—Epitaxy: A new Approach for
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`
`Lateral growth of Gallium Nitride Films”, Journal of Elec-
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`
`
`
`tronic Materials, vol. 28, No. 4., L5-L8, Apr. 1999.
`
`
`
`* cited by examiner
`
`
`
`
`Ex. 1022, Page 2
`
`Ex. 1022, Page 2
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`

`

`
`U.S. Patent
`
`
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`Jun.28, 2005
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`
`
`Sheet 1 of 43
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`US 6,911,351 B2
`
`
`
` Up
`MTSNSNNNSSRS
`PLATTAZIMLALLALLL
`
`
`
`PEEESS
`
`
`
`1Ola
`
`Ex. 1022, Page 3
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`

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`U.S. Patent
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`Jun. 28, 2005
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`Sheet 2 of 43
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`US 6,911,351 B2
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`FIG. 2 (a)
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`
`
`FIG. 2 (b)
`
`=12b
`
`
`
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`
`40 12a 40 12b
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`40
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`Ex. 1022, Page 4
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`Ex. 1022, Page 4
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`U.S. Patent
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`Jun. 28, 2005
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`Sheet 3 of 43
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`US 6,911,351 B2
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`FIG. 3(a)
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`FIG. 3(b)
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`12b
`
`12b
`
`Ex. 1022, Page 5
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`Ex. 1022, Page 5
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`US 6,911,351 B2
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`U.S. Patent
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`Jun.28, 2005
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`Sheet 4 of 43
`
`EAE vOIA
`
`PRAATTRACSSSR
`SnpgsaEee
`LALLAEA
`
`Ex. 1022, Page 6
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`

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`U.S. Patent
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`Jun. 28, 2005
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`Sheet 5 of 43
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`US 6,911,351 B2
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`FIG. 9
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`13
`LLB el era
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`
`
`pipe pe LA
`12
`teu
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`Ex. 1022, Page 7
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`Ex. 1022, Page 7
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`U.S. Patent
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`Jun. 28, 2005
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`Sheet 6 of 43
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`US 6,911,351 B2
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`FIG. 6 (a)
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`FIG. 6 (b)
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`FIG. 6 (c)
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`FIG. 6 (d)
`
`
`
`i4a
`
`l4a
`
`offtLh?
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`
`
`\\PESTAha
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`Ex. 1022, Page 8
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`Ex. 1022, Page 8
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`U.S. Patent
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`Jun. 28, 2005
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`Sheet 7 of 43
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`US 6,911,351 B2
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`FIG. 7
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`MASK OF METAL WITH HIGH MELTING POINT
`
`
`
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`MASK OF DIELECTRIC
`
`
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`
`ROOM TEMPERATURE
`
`EXCITATION WAVELENGTH=325nm
`
`
`
`300
`
`
`
`350
`
`
`
`400
`
`
`
`450
`
`
`
`900
`
`WAVELENGTH (nm)
`
`UNITS)
`
`PL-INTENSITY(ARB.
`
`
`
`550
`
`
`
`600
`
`
`
`650
`
`
`
`
`
`Ex. 1022, Page 9
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`Ex. 1022, Page 9
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`U.S. Patent
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`Jun. 28, 2005
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`Sheet 8 of 43
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`US 6,911,351 B2
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`.
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`24
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`
`
`FIG.8
`
`
`
`q
`
`22
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`23
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`a/;
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`
`
`12a
`
`
`
`Ex. 1022, Page 10
`
`aP
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`
` AVN WAm~O
`
`Ex. 1022, Page 10
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`U.S. Patent
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`Jun.28, 2005
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`Sheet 9 of 43
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`US 6,911,351 B2
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`6O14
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`
`Ex. 1022, Page 11
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`U.S. Patent
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`Jun. 28, 2005
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`Sheet 10 of 43
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`US 6,911,351 B2
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`FIG. 10 (a)
`
`
`
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`40 lla 40 llb
`
`
`
`
`
`lb
`
`
`
`40
`
`
`
`
`FIG. 10 (b)
`
`
`
`lla
`
`
`
`
`{lb
`
`
`11b
`
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`
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`
`
`11A
`
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`Ex. 1022, Page 12
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`Ex. 1022, Page 12
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`Jun. 28, 2005
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`Sheet 11 of 43
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`US 6,911,351 B2
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`RARERSESSA
`BITiteltestIIa
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`TT‘Old
`
`Ex. 1022, Page 13
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`Ex. 1022, Page 13
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`

`
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`GlOld
`
`
`ffDNNSaISs:
`ORaya
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`Ex. 1022, Page 14
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`Jun. 28, 2005
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`Sheet 13 of 43
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`US 6,911,351 B2
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`FIG, 13
`
`
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`LIGHTINTENSITY(a.u.)
`
`
`
`
`60-40 -20
`0
`
`
`ANGLE © )
`
`20
`
`
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`40
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`
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`60
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`Ex. 1022, Page 15
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`Ex. 1022, Page 15
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`Jun. 28, 2005
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`U.S. Patent
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`viOld
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`US 6,911,351 B2
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`IT
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`
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`ERPEERS
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`Ex. 1022, Page 16
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`Sheet 15 of 43
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`US 6,911,351 B2
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`FIG, 15
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`LIGHTINTENSITY(a.u.)
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`-. 4==«5oO 1 2 3
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`DISTANCE FROM ACTIVE LAYER (um)
`
`INDEX
`
`REFRACTIVE
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`Ex. 1022, Page 17
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`Ex. 1022, Page 17
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`Sheet 16 of 43
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`US 6,911,351 B2
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`FIG. 16
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`LIGHTINTENSITY(a.u.)
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`Ex. 1022, Page 18
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`Ex. 1022, Page 18
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`US 6,911,351 B2
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`FIG. 17
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`14c 14b 14c 14a
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`CROSS-SECTION
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`Ex. 1022, Page 19
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`:
`SURFACE PHOTOGRAPH
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`(OPTICAL MICROSCOPE) ©
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`14a
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`Ex. 1022, Page 19
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`Sheet 18 of 43
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`US 6,911,351 B2
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`9Gv2
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`Ex. 1022, Page 20
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`US 6,911,351 B2
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`FIG. 19 (a)
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`ma
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`14B
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`
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`ADSORPTION
`
`
`
`«OEP
`MOLECULE
`
`
`
`& ADSORPTION
`
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`DIFFUSION =
`EVAPORATION\
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`
`
`
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`Te EVAPORATION
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`EVAPORATION
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`NB
`SNELL LLL
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`FIG. 19 (b)
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`MOLECULE
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`GF ADSORPTION
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`EVAPORATION\
`m
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`./EVAPORATION
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`Ex. 1022, Page 21
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`404 .
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`ADSORPTION
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`Ex. 1022, Page 21
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`FIG. 20 (a)
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`FIG. 20 (b)
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`Ex. 1022, Page 22
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`Ex. 1022, Page 22
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`Ex. 1022, Page 23
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`US 6,911,351 B2
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`FIG. 28 (a)
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`FIG. 28 (b)
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`Ex. 1022, Page 30
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`FIG. 29 (a)
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`FIG. 29 (b)
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`Ex. 1022, Page 31
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`FIG. 30 (a)
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`Ex. 1022, Page 32
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`Ex. 1022, Page 32
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`Ex. 1022, Page 33
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`Ex. 1022, Page 34
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`Sheet 34 of 43
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`Sheet 35 of 43
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`Sheet 36 of 43
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`FIG. 36 (a)
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`Ex. 1022, Page 38
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`Ex. 1022, Page 38
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`Sheet 37 of 43
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`FIG. 37
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`PRIOR ART
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`Ex. 1022, Page 39
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`Ex. 1022, Page 39
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`Ex. 1022, Page 40
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`Ex. 1022, Page 40
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`Ex. 1022, Page 41
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`Ex. 1022, Page 41
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`Sheet 40 of 43
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`PRIOR ART
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`FIG. 40 (a)
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`PRIOR ART
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`FIG. 40 (b)
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`FIG. 40 (c)
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`FIG. 40 (d)
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`Ex. 1022, Page 42
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`FIG. 41
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`PRIOR ART
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`LIGHTINTENSITY(a.u.)
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`REFRACTIVE
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`INDEX
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`-1 4~5Oo 2.1L. 2 3
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`DISTANCE FROM ACTIVE LAYER (um)
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`Ex. 1022, Page 43
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`Ex. 1022, Page 43
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`Sheet 42 of 43
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`FIG. 42
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`PRIOR ART
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`INTENSITY(a.u.)
`LIGHT
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`ANGLE ( )
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`Ex. 1022, Page 44
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`Ex. 1022, Page 44
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`US 6,911,351 B2
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`FIG. 43
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`PRIOR ART
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`(M PLANE)
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`302
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`301
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`Ex. 1022, Page 45
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`Ex. 1022, Page 45
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`US 6,911,351 B2
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`1
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`METHOD OF FABRICATING NITRIDE
`
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`SEMICONDUCTOR, METHOD OF
`
`
`FABRICATING NITRIDE SEMICONDUCTOR
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`DEVICE, NITRIDE SEMICONDUCTOR
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`DEVICE, SEMICONDUCTOR LIGHT
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`EMITTING DEVICE AND METHOD OF
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`FABRICATING THE SAME
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`CROSS-REFERENCED TO RELATED
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`APPLICATIONS
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`This application is a Divisional of application Ser. No.
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`09/712,127 filed Nov. 15, 2000, now U'S. Pat. No. 6,720,
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`586 issued Apr. 13, 2004.
`BACKGROUND OF THE INVENTION
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`The present invention relates to a method of fabricating a
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`nitride semiconductor for use in a short-wavelength semi-
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`conductor laser diode and the like expected to be applied to
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`the fields of optical information processing and the like, a
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`semiconductor device and a semiconductor light emitting
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`device using the nitride semiconductor and a method of
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`fabricating the same.
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`Recently, a nitride semiconductor of a group II-V
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`compound,that is, a group V element including nitride (N),
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`is regarded as a promising material for a short-wavelength
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`light emitting device due to its large energy gap.
`In
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`particular, a gallium nitride-based compound semiconductor
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`(Al,Ga,In,N, wherein 03x, y, zS1 and x+y+z=1) has been
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`earnestly studied and developed, resulting in realizing a
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`practical blue or green light emitting diode (LED) device.
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`Furthermore, in accordance with capacity increase of an
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`optical disk unit, a semiconductor laser diode lasing at
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`approximately 400 nm is earnestly desired, and a semicon-
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`ductor laser diode using a gallium nitride-based semicon-
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`ductor is to be practically used.
`CONVENTIONAL EXAMPLE1
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`Now, a gallium nitride-based semiconductor laser diode
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`according to Conventional Example 1 will be described with
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`reference to drawings.
`FIG. 37 showsthe sectional structure of the conventional
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`gallium nitride-based semiconductor laser diode showing
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`laser action. As is shown in FIG. 37,
`the conventional
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`semiconductor laser diode includes a buffer layer 302 of
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`gallium nitride (GaN), an n-type contact layer 303 of n-type
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`GaN, an n-type cladding layer 304 of n-type aluminum
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`gallium nitride (AlGaN), an n-type light guiding layer 305
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`of n-type GaN,a multiple quantum well (MQW)activelayer
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`306 including gallium indium nitride layers having different
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`composition ratios of indium (Ga,_,In,N/Ga,_,In,N,
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`wherein O<y<x<1), a p-type light guiding layer 307 of
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`p-type GaN, a p-type cladding layer 308 of p-type AlGaN
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`and a p-type contact layer 309 of p-type GaN successively
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`formed on a substrate 301 of sapphire by, for example, metal
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`organic vapor phase epitaxial growth (MOVPE).
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`An upperportion of the p-type cladding layer 308 and the
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`p-type contact layer 309 is formed into a ridge with a width
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`of approximately 3 through 10 wm. A lamination body
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`including the MQW active layer 306 is etched so as to
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`expose part of the n-type contact layer 303, and the upper
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`face and the side faces of the etched lamination body are
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`insulating film 310 above the p-type contact layer 309, a
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`ohmic contact with the p-type contact layer 309 through the
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`opening is formed over a portion of the insulating film 310
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`layer 303 not covered with the insulating film 310, an n-side
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`electrode 312 in ohmic contact with the n-type contact layer
`303 is formed.
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`In the semiconductor laser diode having the aforemen-
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`the p-side electrode 311 with the n-side electrode 312
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`grounded, optical gain is generated within the MQW active
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`layer 306, so as to show laser action at a wavelength of
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`The wavelength of laser action depends upon the com-
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`position ratios x and y or the thicknesses of the Ga,_.In.N
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`and Ga,_,In,N layers includedin the MQWactivelayer 306.
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`At present, the laser diode having this structure has been
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`developed to show continuouslaser action at room tempera-
`ture or more.
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`Furthermore,laser action in the fundamental mode of the
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`lateral mode along a horizontal direction (parallel to the
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`substrate surface) can be shown by adjusting the width or
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`height of the ridge. Specifically,
`the laser action of the
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`fundamental lateral mode can be shown by providing a
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`difference in the light confinement coefficient between the
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`fundamental lateral mode and a primary or higher mode.
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`The substrate 301 is formed from, apart from sapphire,
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`silicon carbide (SiC), neodymium gallate (NdGaO,) or the
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`like, and any of these materials cannot attain lattice match
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`with gallium nitride andis difficult to attain coherent growth.
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`As a result, any of these materials includes a large number
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`of mixed dislocations, namely, mixed presence of edge
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`dislocations, screw dislocations and other dislocations. For
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`example, when the substrate is made from sapphire, the
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`substrate includes dislocations at a density of approximately
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`1x10° cm™*, which degrades thereliability of the semicon-
`ductor laser diode.
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`As a method for reducing the density of dislocations,
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`epitaxial
`lateral overgrowth (ELOG) has been proposed.
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`This is an effective method for reducing threading disloca-
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`tions in a semiconductor crystal with large lattice mismatch.
`CONVENTIONAL EXAMPLE 2
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`FIG. 38 schematically shows the distribution of crystal
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`dislocations in a semiconductor layer of gallium nitride
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`formed by the ELOG.
`The outline of the ELOG will be described with reference
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`to FIG. 38. First, a seed layer 402 of GaN is grown on a
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`substrate 401 of sapphire by the MOVPEorthe like.
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`Next, a dielectric film of silicon oxide or the like is
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`deposited by chemical vapor deposition (CVD)orthe like,
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`and the deposited dielectric film is formed into a mask film
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`403 having an opening pattern in the shape of stripes with a
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`predetermined cycle by photolithography and etching.
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`Then, a semiconductor layer 404 of GaN is formed on the
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`mask film 403 by selective growth with portions of the seed
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`layer 402 exposed from the mask film 403 used as a seed
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`crystal by the MOVPE or halide vapor phase epitaxial
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`growth.
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`Atthis point, although a dislocation high-density region
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`404a wherethe dislocation density is approximately 1x10°
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`cm”? is formed in a portion of the semiconductor layer 404
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`above the opening of the mask film 403, a dislocation
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`low-density region 404b where the dislocation density is
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`approximately 1x10’ cm”? can be formed in a portion ofthe
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`semiconductor layer 404 laterally grown on the mask film
`403.
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`Ex. 1022, Page 46
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`Ex. 1022, Page 46
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`

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`US 6,911,351 B2
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`FIG. 39 showsthe sectional structure of a semiconductor
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`Thirdly, the semiconductor laser diode of Conventional
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`laser diode whose active area, namely, a ridge working as a
`Example 1 has a problem that, in dividing plural laser diodes
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`current injecting region, is formed above the dislocation
`formed on a wafer into individual
`laser chips by,
`for
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`low-density region 4045. In FIG. 39, like reference numerals
`example, cleavage, the facet of the cavity cannot be flat
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`are used to refer to like elements shown in FIGS. 37 and 38.
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`because the substrate of sapphire and the nitride semicon-
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`ductor layer have different crystal planes. Specifically, as is
`When the current injecting region is formed above the
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`shown in FIG. 43, sapphire forming the substrate 301 is
`dislocation low-density region 404b of the MQW active
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`easily cleaved on the (1-100) surface orientation, namely,
`layer 306 in this manner, the reliability of the laser diode can
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`the so-called M plane, and hence, the substrate is generally
`be improved.
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`cleaved on the M plane of sapphire.
`As a result of various examinations, the present inventors
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`have found that semiconductor laser diodes according to
`However,
`the M plane of a nitride semiconductor, for
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`Conventional Examples 1 and 2 have the following prob-
`example, gallium nitride is shifted from the M plane of
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`lems:
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`sapphire by 30 degrees in the plane, and hence, the M plane
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`of sapphire accords with the (11-20) surface orientation,
`First,
`the problems of the growth method of a nitride
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`namely,
`the so-called A plane, of gallium nitride.
`semiconductor by the ELOG according to Conventional
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`Accordingly, when the substrate 301 is cleaved, cleaved
`Example 2 will be described.
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`ends of the buffer layer 302 and the lamination body above
`FIGS. 40(@) through 40(d) schematically show a state
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`are shifted from that of the substrate 301 by 30 degrees so
`where polycrystals 405 of gallium nitride are deposited on
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`as to appear as an irregular face with level differences of
`the mask film 403 during the growth of the semiconductor
`several hundreds nm.
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`layer 404 so as to degrade the crystallinity of the semicon-
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`Whenthe cavity facet is such an irregular face, mirror loss
`ductor layer 404.
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`of laser at the cavity facet is increased, so as to increase the
`Specifically, the mask film 403 having the openingsisfirst
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`operation current of the semiconductor laser diode, which
`formed on the seed layer 402 as is shownin FIG. 40(a), and
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`can degrade the reliability of the semiconductor laser diode.
`plural semiconductor layers 404 are respectively grown by
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`Furthermore, since the irregularities are randomly formed on
`using, as the seed crystal, the portions of the seed layer 402
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`the cavity facet, it is difficult to form with good reproduc-
`exposed in the openings of the mask film 403 as is shown in
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`ibility a cavity facet having a predetermined reflectance,
`FIG. 40(6). At this point, since the mask film 403 is formed
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`which lowers the yield. Even when the cavity is formed not
`from a dielectric, plural polycrystals 405 that cannot be
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`by cleavage but by dry etching, the same problem arises.
`crystallized on a dielectric may be deposited on the mask
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`film 403.
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`Herein, a minus sign “-” used in a surface orientation
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`indicates inversion of an index following the minussign.
`Next, as is shown in FIGS. 40(c) and 40(d), when the
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`On the other hand, in the semiconductor laser diode of
`plural semiconductor layers 404 are grownto be integrated
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`Conventional Example 2, the stripe-shaped opening of the
`and to haveaflat face with the polycrystals 405 deposited,
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`35
`mask film 403 for the selective growth is formed parallel to
`a region 404¢ with poor crystallinity is formed on each
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`the M-axis of the semiconductor layer 404. This is because
`polycrystal 405.
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`a rate of the lateral growth along the A-axis is much higher
`The present inventors have found that a laser diode with
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`than in other directions, and hence, the selective growth can
`good characteristics cannot be obtained when the current
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`be effectively proceeded in a short period of time. Therefore,
`injecting region is formed above the region 404c¢ with poor
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`the dislocation low-density region 4045 is parallel to the
`crystallinity.
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`M-axis, and therefore, the cavity facet of the laser diode
`Second, the present inventors have found a problem that,
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`formed above the dislocation low-density region naturally
`in the semiconductor laser diode according to Conventional
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`accords with the M plane. Asaresult, it is necessary to
`Example 1 or 2, it is difficult to increase the light confine-
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`cleave the substrate 401 on the A plane. Although sapphire
`mentcoefficient of the active layer along a direction vertical
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`to the substrate surface.
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`can be easily cleaved on the M plane as described above,it
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`cannot be easily cleaved on the A plane, which largely
`FIG. 41 showsthe relationship, in the semiconductorlaser
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`lowers the yield of the semiconductor laser diode.
`diode of Conventional Example 1, between the distribution
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`Fourthly,
`it is known that an angle (tilt) between the
`of a refractive index of the MQWactive layer 306 along the
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`direction vertical to the substrate surface and the distribution
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`C-axis of the seed layer 402 and the C-axis of the semicon-
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`ductor layer 404 selectively grown above the seed layer 402
`of light intensity on a cavity facet. It is understood that part
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`is approximately 0.1 through 1 degree in the ELOG.
`of generated light confined within the MQWactive layer 306
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`Onthe other hand, when the ELOG is conducted again by
`leaks to the substrate 301 so as to generate a standing wave
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`using the dislocation low-density region 4045 obtained by
`in the n-type contact layer 303. When the generated light is
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`the ELOG asthe seed crystal and covering the dislocation
`thus largely leaked from the MQW active layer 306 to the
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`high-density region 404a with another mask film for selec-
`substrate 301, the light confinementratio in the MQW active
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`tive growth, a nitride semiconductor crystal can be obtained
`layer 306 is lowered, resulting in increasing the threshold
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`value for laser action.
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`merely from the dislocation low-density region 4045.
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`Accordingly, a cavity having a facet according to the A plane
`Also, FIG. 42 showsa far-field pattern of the laser diode
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`can be formed on the crystal formed from merely the
`of Conventional Example 1. In this drawing, the abscissa
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`dislocation low-density region 4046, resulting in largely
`indicates a shift of emitted light from the normaldirection of
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`increasing the yield in the cleavage.
`the cavity facet toward the horizontal direction (along the
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`substrate surface), and the ordinate indicateslight intensity
`When the cavity is formed along the A-axis, however, a
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`of the emitted light. When the generated light is largely
`waveguide is formed in a zigzag manner along the C-axis
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`leaked to the substrate 301 as in Conventional Example 1, it
`because of the tilt of the C-axis between the seed layer 402
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`is also difficult to obtain a unimodal far-field pattern. This
`and the selectively grown layer above the seed layer 402 as
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`goes for the semiconductor laser diode of Conventional
`described above. Such a zigzag waveguide causes
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`Example 2.
`waveguide loss, resulting in a problem of increase of the
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`Ex. 1022, Page 47
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`Ex. 1022, Page 47
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`

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`semiconductor layer of Al.Ga,In,N, wherein OSx, y, z31
`operation current of the laser diode. Moreover,in a vertical
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`an