Petitioner Bluehouse Global Ltd.
`Petitioner Bluehouse Global Ltd.
`
`Ex. 1005
`
`EX. 1005
`
`

`

`(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2007/0072439 A1
`
`Akimoto et al. Mar. 29, 2007 (43) Pub. Date:
`
`
`US 20070072439A1
`
`(54) SEMICONDUCTOR DEVICE AND
`MANUFACTURING METHOD THEREOF
`
`(30)
`
`Foreign Application Priority Data
`
`(75)
`
`Inventors: Kengo Akimoto, Atsugi (JP); Tatsuya
`Honda, lsehara (JP); Norihito Sone,
`.
`Atsugl (JP)
`
`Correspondence Address:
`COOK, ALEX, McFARRON, MANZO,
`CUMMINGS & MEHLER: LTD-
`SUITE 2850
`200 WEST ADAMS STREET
`CHICAGO, IL 60606 (US)
`
`(73) Assignee: Semiconductor Energy Laboratory
`Co., Ltd.
`
`(21) Appl. No.:
`
`11/524,549
`
`(22)
`
`Filed:
`
`Sep. 21, 2006
`
`Sep. 29, 2005
`
`(JP) ...................................... 2005-283782
`
`Publication Classification
`
`(51)
`
`Int. Cl.
`(2006.01)
`H01L 21/00
`(52) US. Cl.
`.............................................................. 438/795
`
`ABSTRACT
`(57)
`An object is to provide a semiconductor device of which a
`manufacturing process is not complicated and by which cost
`can be suppressed, by forming a thin film transistor using an
`oxide semiconductor film typified by zinc oxide, and a
`manufacturing method thereof. For
`the semiconductor
`device, a gate electrode is formed over a substrate; a gate
`insulating film is formed covering the gate electrode; an
`oxide semiconductor film is formed over the gate insulating
`film; and a first conductive film and a second conductive film
`are formed over the oxide semiconductor film. The oxide
`semiconductor film has at least a crystallized region in a
`channel region.
`
`105
`
`101
`
`105
`
`102
`
`LRTA
`
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`

`Patent Application Publication Mar. 29, 2007 Sheet 1 0f 21
`
`US 2007/0072439 A1
`
`101
`
`105
`
`102
`
`102
`
`105
`
`104 '
`
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`Patent Application Publication Mar. 29, 2007 Sheet 2 0f 21
`
`US 2007/0072439 A1
`
`
`
`
`
`“9:308$395308DEX
`
`544332211.
`0000000000000000000000000000000505050505
`
`
`
`
`
`
`as-deposited
`
`200°C1 hr
`
`300°C1 hr
`
`350°C1 hr
`
`a heat treatment temperature dependency of a crystallinity of ZnO
`(XRD (002) intensity gas using for forming Zn0:Ar/02=50/5sccm)
`
`FIG. 2
`
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`Patent Application Publication Mar. 29, 2007 Sheet 3 0f 21
`
`US 2007/0072439 A1
`
`FIG. 3A
`
`LRTA
`
`
`I’AY’IA'IIYIIAYIIX'IAYIIL'IAXO
`
`308
`
`FIG. 3C
`
`308
`
`309
`
`309
`
`
`
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`.
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`IAWYIIA'YI X’IAYIIX'IAYIIA'IO
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`{IIIIA "
`Q‘ Vlllli‘.
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`l
`
`307
`
`306
`
`305
`
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`Patent Application Publication Mar. 29, 2007 Sheet 4 0f 21
`
`US 2007/0072439 A1
`
`-
`FIG. 4A
`VIII/[III],IIIII/IIIIIII'IIIII[III/IIIIIIIIIIIIIIIII
`
`401
`
`L——Agr
`FIG. 4B
`:402
`40°
`
`FIG. 4C
`
`403;a 403:
`
`FIG'4Diiiiiii404
`
`LRTA
`
`FIG. 4E
`
`434
`__
`WW
`
`424
`
`T________T
`
`FIG.
`
`FIG.
`
`FIG.
`
`a 406
`
`405
`
`
`
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`

`

`Patent Application Publication Mar. 29, 2007 Sheet 5 0f 21
`
`US 2007/0072439 A1
`
`FIG. 5A
`
`409
`
`”III/[IA
`
`FIG. SB
`
`413
`
`413
`
`FIG. 50
`
`I.mn”
`
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`
`

`

`Patent Application Publication Mar. 29, 2007 Sheet 6 0f 21
`
`US 2007/0072439 A1
`
`FIG. 6A
`
`so:
`
`'
`
`603:
`
`603b
`
`;
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`.
`
`LRTA 604
`FIG. GB
`HH
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`i
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`
`
`BLUEHOUSE EXHIBIT 1005
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`Patent Application Publication Mar. 29, 2007 Sheet 7 0f 21
`
`US 2007/0072439 A1
`
`FIG.
`
`7
`
`
`
`
`
`\\\\\\\\\.\\\I\mu\\kh\\\\\\_—Ilj////////l—/Jlxn/zfizz///x\l’
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`
`BLUEHOUSE EXHIBIT 1005
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`

`

`Patent Application Publication Mar. 29, 2007 Sheet 8 0f 21
`
`US 2007/0072439 A1
`
`FIG. 8A
`
`
`
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`

`

`Patent Application Publication Mar. 29, 2007 Sheet 9 0f 21
`
`US 2007/0072439 A1
`
`FIG. 9A
`
`
`
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`

`

`Patent Application Publication Mar. 29, 2007 Sheet 10 of 21
`
`US 2007/0072439 A1
`
`FIG. 10A
`
`1400
`
`—L A0com
`
`VIII,”
`
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`
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`

`Patent Application Publication Mar. 29, 2007 Sheet 11 0f 21
`
`US 2007/0072439 A1
`
`FIG. 11
`
`WWWWWMW'mm”mmmmm'IMI’WWWM
`
`
`
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`
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`

`

`Patent Application Publication Mar. 29, 2007 Sheet 12 of 21
`
`US 2007/0072439 A1
`
`9701
`
`9702
`9101
`
`
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`

`

`Patent Application Publication Mar. 29, 2007 Sheet 13 0f 21
`
`US 2007/0072439 A1
`
`All"5an_mx_a
`
`I'll-III
`
`8h825NE_o:N:E
`
`mr///////////?////////////////.1.NN.$2
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`mm?
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`
`
`
`
`
`

`

`Patent Application Publication Mar. 29, 2007 Sheet 14 of 21
`
`US 2007/0072439 A1
`
`FIG. 14A
`
`8
`
`FIG. 14B
`
`1
`
`1 50
`
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`1 503
`
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`
`pixel portion
`
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`

`

`Patent Application Publication Mar. 29, 2007 Sheet 15 0f 21
`
`US 2007/0072439 A1
`
`FIG. 15
`
`
`
`
`
`mwmmmmmw5mmNwmw.me
`
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`
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`
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`
`
`
`BLUEHOUSE EXHIBIT 1005
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`
`
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`

`

`Patent Application Publication Mar. 29, 2007 Sheet 16 of 21
`
`US 2007/0072439 A1
`
`
`
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`

`Patent Application Publication Mar. 29, 2007 Sheet 17 0f 21
`
`US 2007/0072439 A1
`
`FIG. 17A
`
`
`
`FIG. 17B
`
`
`
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`

`Patent Application Publication Mar. 29, 2007 Sheet 18 of 21
`
`US 2007/0072439 A1
`
`FIG. 1 8A
`
`803 signal line driver circuit
`
`SP. CLK
`
`video signal
`
`308
`
`JaAngeuu
`unaigo
`
`JepnqL08
`
`801 pixel portion
`
`805 analog switch
`fiuiuueos
`1019591mus908
`
`813 signal line driver circuit
`
`SP, CLK
`
`FIG. 18B
`
`SP, CLK
`
`
` video signal
`
`
`
`
`
`
`815 latch A
`
`817 DAC
`
`218
`
`0.8_.
`2"!)
`(D:
`~12.
`03
`:10
`0:.
`
`E:r-O-(‘D
`
`8‘1 1 pixel portion
`
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`Patent Application Publication Mar. 29, 2007 Sheet 19 of 21
`
`US 2007/0072439 A1
`
`FIG. 19A
`
`1904
`
`000
`
`000
`
`: ”III/4'4
`
`1905Fé 1906
`WW 1902
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`
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`
`FIG. 198
`
`Temp.
`
`Pre-Heat
`Post-Heat
`
`
`Time
`
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`Patent Application Publication Mar. 29, 2007 Sheet 20 of 21
`
`US 2007/0072439 A1
`
`FIG 20
`
`2010
`
`2011
`
`
`
`2013
`
`2014
`
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`

`Patent Application Publication Mar. 29, 2007 Sheet 21 of 21
`
`US 2007/0072439 A1
`
`FIG. 21
`
`21”
`
`2110
`
`2114
`
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`

`US 2007/0072439 A1
`
`Mar. 29, 2007
`
`SEMICONDUCTOR DEVICE AND
`MANUFACTURING METHOD THEREOF
`
`BACKGROUND OF THE INVENTION
`
`[0001]
`
`1. Field of the Invention
`
`[0002] The present invention relates to a semiconductor
`device and a manufacturing method thereof and particularly
`relates to a semiconductor device using an oxide semicon-
`ductor. The present invention also relates to an electronic
`appliance equipped with the semiconductor device.
`
`[0003]
`
`2. Description of the Related Art
`
`[0004] Flat panel displays (FPD), typified by liquid crystal
`displays (LCD) and EL displays, have attracted attention as
`the display device replacing conventional CRTs. The devel-
`opment of large screen liquid crystal television mounted
`with an active matrix-driven large scale liquid crystal panel
`is particularly an important challenge which liquid crystal
`panel makers should focus on. In addition, large screen EL
`television is also being developed.
`
`In the conventional liquid crystal device or elec-
`[0005]
`troluminescence display device (hereinafter referred to as a
`light emitting display device or an EL display device), a thin
`film transistor (hereinafter referred to as TFT) is used, which
`uses crystalline silicon or amorphous silicon as a semicon-
`ductor element driving each pixel.
`
`[0006] A TFF using a crystalline silicon film has a higher
`mobility by two digits or more compared to a TFT using an
`amorphous silicon film, and has potential for high speed
`operation when it is used for a scanning line driver circuit for
`selecting a pixel of a light emitting display device, a signal
`line driver circuit for sending video signals to a selected
`pixel, or the like. However, using crystalline silicon for a
`semiconductor
`film complicates manufacturing
`steps
`because of crystallization of the semiconductor film com-
`pared to using amorphous silicon for the semiconductor
`film; therefore, there are drawbacks of yield decrease by that
`much and increase in cost. Further, a heating temperature for
`the crystallization is 550° C. or higher, and it is difficult to
`use a substrate made of a resin with low melting point, a
`plastic substrate, or the like.
`
`the TFT using amorphous
`[0007] On the other hand,
`silicon for a semiconductor film can be manufactured at low
`
`cost, since it is not heated at a high temperature and a resin
`substrate or a plastic substrate can be used. However, a
`mobility of only around 0.2 to 1.0 cm2/V~s at most can be
`obtained with a TFT of which a channel forming region is
`formed with a semiconductor film formed of amorphous
`silicon, and it also has high power consumption.
`
`[0008] A plasma CVD method is commonly used when an
`amorphous silicon film is formed over a substrate. Film
`formation by a plasma CVD method requires heating under
`high vacuum, and damage to a plastic substrate or an organic
`resin film over a substrate is a concern. In addition to the
`
`concern in forming the amorphous silicon film by a plasma
`CVD method, there is also a concern in forming the film by
`a sputtering method which is that a thin insulating film might
`be formed over a surface of an amorphous silicon film when
`the amorphous silicon film is exposed to atmospheric air.
`
`[0009] As a material to replace a semiconductor made of
`such silicon, forming a TFT using an oxide semiconductor
`
`such as zinc oxide for a channel forming region has been
`reported in recent years (for example, refer to Patent Docu-
`ment 1: Japanese Patent Laid-Open No. 2000-150900, and
`Non-Patent document 1: Elvira M. C. Fortunato, et al.
`Applied Physics Letters, Vol. 85, No. 13, P2541 (2004)).
`Since the oxide semiconductor has mobility equal to or
`higher than that of a TFT formed with a semiconductor
`including amorphous silicon, further characteristic improve-
`ment is demanded.
`
`SUMMARY OF THE INVENTION
`
`In view of the foregoing problems, an object of the
`[0010]
`invention is to provide a semiconductor device
`present
`including a semiconductor element with improved charac-
`teristics and a manufacturing method thereof.
`
`[0011] On another front, size increase in substrate has
`advanced for manufacturing a large-area device by a cheaper
`process, as in liquid crystal television. However, with the
`size increase in substrate, there is a problem of being easily
`effected by bending and warping. Also, when a substrate is
`heated to a high temperature during a heat treatment step, a
`size of the substrate becomes distorted due to warping and
`shrinking, and there is a problem of a decrease in precision
`of alignment in a photolithography step.
`
`[0012] Consequently, an object of the present invention is
`to provide a technique that makes it possible to manufacture
`with good yield a semiconductor device over a large sub-
`strate, having for example a side longer than 1 meter, in a
`crystallization step of a semiconductor element used in a
`semiconductor device.
`
`[0013] As mentioned above, an object of the present
`invention is to provide a semiconductor device including a
`semiconductor element with characteristics that are further
`
`improved, which can be manufactured at lower cost and
`more favorable productivity than before.
`
`In the present invention, a compound semiconduc-
`[0014]
`tor, more preferably an oxide semiconductor is used as a
`semiconductor. As the oxide semiconductor, for example,
`zinc oxide (ZnO), InGaO3(ZnO)5, magnesium zinc oxide
`(ngZn1_xO), cadmium zinc oxide (Cden1_xO), cadmium
`oxide (CdO), an 1114217an based amorphous oxide
`semiconductor (a-IGZO), or the like is used. Also, the gist
`of the present invention is that by heating a gate electrode
`that is near the compound semiconductor by lamp rapid
`thermal annealing (LRTA; also simply called lamp heating),
`crystallization of the compound semiconductor is selectively
`promoted, and a TFT using a compound semiconductor
`having the region in which crystallization is promoted at
`least in a channel region can be manufactured.
`
`[0015] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed covering the gate electrode, and an oxide semicon-
`ductor film formed over the insulating film. The oxide
`semiconductor film includes a first oxide semiconductor
`
`region and a second oxide semiconductor region, and the
`first oxide semiconductor region that is formed in a position
`which overlaps with the gate electrode has higher crystal-
`linity than the second semiconductor region. Note that
`“crystallinity” expresses a degree of regularity of atomic
`arrangement inside of crystal, and when manufacturing a
`TFT using an oxide semiconductor film with favorable
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`US 2007/0072439 A1
`
`Mar. 29, 2007
`
`crystallinity (also expressed as having high crystallinity or
`with improved crystallinity), an electrical characteristic
`thereof is favorable.
`
`[0016] One feature of the present invention is to have a
`gate electrode and an oxide semiconductor film over a
`substrate. In a region of the oxide semiconductor film which
`overlaps with the gate electrode via an insulating film, a
`portion of the region is crystallized.
`
`[0017] One feature of the present invention is to have a
`gate electrode, an oxide semiconductor film, and a conduc-
`tive film over a substrate. The conductive film is provided to
`be in contact with the oxide semiconductor film, and in a
`region of the oxide semiconductor film which overlaps with
`the gate electrode via an insulating film, a portion of the
`region is crystallized.
`
`[0018] One feature of the present invention is to have a
`gate electrode over a substrate, an insulating film formed
`covering the gate electrode, and an oxide semiconductor
`film formed over the insulating film. The oxide semicon-
`ductor film is crystallized in at least a region which overlaps
`with the gate electrode. Note that “crystallization” refers to
`generation of crystal nuclei from an amorphous state, or
`growth of crystal grains from a state in which crystal nuclei
`have been generated.
`
`[0019] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed covering the gate electrode, a conductive film
`formed over the insulating film, and an oxide semiconductor
`film formed over the insulating film and the conductive film.
`The oxide semiconductor film is crystallized in at least a
`region which overlaps with the gate electrode.
`
`[0020] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed covering the gate electrode, a conductive film
`formed over the insulating film, and an oxide semiconductor
`film formed over the insulating film and the conductive film.
`The gate electrode has lower reflectivity with respect to a
`light source used for crystallization than the conductive film.
`Note that reflectivity comparison is used when the conduc-
`tive film is a metal film or the like having a light shielding
`property.
`
`[0021] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed covering the gate electrode, a conductive film
`formed over the insulating film, and an oxide semiconductor
`film formed over the insulating film and the conductive film.
`The gate electrode has higher heat absorption rate than the
`conductive film.
`
`[0022] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed over the gate electrode, and an oxide semiconductor
`film formed over the insulating film, and by performing
`LRTA on the gate electrode, a portion of the oxide semi-
`conductor film that overlaps with the gate electrode is
`crystallized.
`
`[0023] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed covering the gate electrode, and an oxide semicon-
`ductor film formed over the insulating film. By performing
`LRTA on the gate electrode, a first oxide semiconductor
`
`region and a second oxide semiconductor region are formed
`inside of the oxide semiconductor film, and the first oxide
`semiconductor region that is formed in a position which
`overlaps with the gate electrode has higher crystallinity than
`the second oxide semiconductor region.
`
`[0024] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed over the gate electrode, a conductive film formed
`over the insulating film, and an oxide semiconductor film
`formed over the insulating film and the conductive film. By
`performing LRTA on the gate electrode, a portion of the
`oxide semiconductor film is selectively crystallized.
`
`[0025] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed covering the gate electrode, an oxide semiconductor
`film formed over the insulating film, and a conductive film
`formed over the oxide semiconductor film. By performing
`LRTA on the gate electrode, a portion of the oxide semi-
`conductor film is selectively crystallized.
`
`[0026] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed covering the gate electrode, a conductive film
`formed over the insulating film, and an oxide semiconductor
`film formed over the insulating film and the conductive film.
`By performing LRTA on the gate electrode, a first oxide
`semiconductor region and a second oxide semiconductor
`region are formed inside of the oxide semiconductor film. At
`this time, the first oxide semiconductor region that is formed
`in a position which overlaps with the gate electrode has
`higher crystallinity than the second oxide semiconductor
`region.
`
`[0027] One feature of the present invention is to have a
`gate electrode formed over a substrate, an insulating film
`formed covering the gate electrode, an oxide semiconductor
`film formed over the insulating film, and a conductive film
`formed over the oxide semiconductor film. By lamp heating
`the gate electrode, a first oxide semiconductor region and a
`second oxide semiconductor region are formed inside of the
`oxide semiconductor film. At
`this time,
`the first oxide
`conductive region that is formed in a position which over-
`laps with the gate electrode has higher crystallinity than the
`second oxide semiconductor region.
`
`[0028] Note that the foregoing conductive film is formed
`with one element or a plurality of elements selected from Al,
`Ti, Cu, Au, Ag, Mo, Ni, Ta, Zr, and Co.
`
`[0029] Note that it is favorable that the foregoing oxide
`semiconductor film includes at least zinc oxide (ZnO). For
`example,
`lnGaO3(ZnO)5, ngan_XO or Cdenl_xO is
`given.
`
`the foregoing substrate is any one
`[0030] Note that
`selected from an organic resin substrate, an inorganic resin
`substrate, a plastic substrate, and a glass substrate.
`
`[0031] Note that the foregoing oxide semiconductor film is
`formed by a sputtering method.
`
`[0032] Note that nitrogen may be added to the foregoing
`oxide semiconductor film. When adding nitrogen, nitrogen
`works as an acceptor impurity when the oxide semiconduc-
`tor film shows an n-type semiconductor property. Conse-
`quently, a threshold voltage of a transistor manufactured
`using an oxide semiconductor film to which nitrogen is
`added, can be controlled.
`
`BLUEHOUSE EXHIBIT 1005
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`
`Mar. 29, 2007
`
`[0033] One feature of the present invention is to use one
`of W, TaN, and Cr as a gate electrode, or an alloy including
`any one thereof
`
`[0034] One feature of the present invention is to perform
`crystallization of an oxide semiconductor film by irradiation
`with lamp light of a halogen lamp.
`
`[0035] One feature of the present invention is to use light
`in a wavelength region of 800 nm to 2400 nm as lamp light.
`Also, wavelength in the visible light region or the infrared
`light region is used.
`
`[0036] One feature of the present invention is a liquid
`crystal television or an EL television including the foregoing
`semiconductor device.
`
`[0037] Also, in the present invention, a heating treatment
`may be performed by laser light irradiation instead of LRTA.
`For example, laser light irradiation may be performed using
`an infrared light laser, a visible light laser, an ultraviolet
`laser, or the like to selectively improve crystallinity of an
`oxide semiconductor film. Alternatively, laser light irradia-
`tion may be performed at the same time as performing lamp
`heating to selectively improve crystallinity of the oxide
`semiconductor film. When laser irradiation is used, a con-
`tinuous wave laser beam (CW laser beam) or a pulsed laser
`beam (pulse laser beam) can be used. A laser beam that can
`be used here is one or a plurality of that which oscillates
`from a gas laser such as an Ar laser, Kr laser, or an excimer
`laser; a laser of which a medium is a monocrystalline YAG,
`YVO4, forsterite (MgZSiO4), YAlO3, or GdVO4 doped with
`one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta, or
`polycrystalline (ceramic) YAG, YZO3, YVO4, YAlO3, or
`GdVO4, doped with one or more of Nd, Yb, Cr, Ti, Ho, Er,
`Tm, and Ta; a glass laser; a ruby laser; an alexandrite laser;
`a Ti:sapphire laser; a copper vapor laser; and a gold vapor
`laser. By emitting a laser beam from the second harmonic to
`the fourth harmonic of the fundamental harmonic of such a
`
`laser beam, crystallinity can be made to be favorable. Note
`that it is preferable to use laser light having larger energy
`than a band gap of the oxide semiconductor film. For
`example, laser light emitted from a KrF, ArF, XeCl, or an
`XeF excimer laser oscillator may be used.
`
`In the present invention, a semiconductor device
`[0038]
`refers to a device having a circuit including a semiconductor
`element (such as a transistor or a diode), and as the semi-
`conductor device, an integrated circuit including a semicon-
`ductor element, a display device, a wireless tag, an IC tag,
`and the like are given. As the display device, a liquid crystal
`display device, a light emitting device, a DMD (digital
`micromirror device), a PDP (plasma display panel), an FED
`(field emission display), an electrophoresis display device
`(electronic paper), and the like are typically given.
`
`In the present invention, a display device refers to
`[0039]
`a device using a display element, in other words, an image
`display device. Further, a module in which a connector, for
`example an FPC (flexible printed circuit), a TAB (tape
`automated bonding) tape, or a TCP (tape carrier package), is
`attached to a display panel; a module provided with a printed
`wiring board at an end of the TAB tape or the TCP; and a
`module in which an IC (integrated circuit) or a CPU is
`directly mounted on a display element by COG (chip on
`glass) method are all included as the display device.
`
`In the present invention, it is acceptable as long as
`[0040]
`crystallization of an oxide semiconductor film is caused or
`
`crystallinity is improved in at least a channel forming region.
`Further, the entire channel forming region is not required to
`be crystallized, and it is acceptable as long as at least a
`portion of the channel forming region on a gate electrode
`side is crystallized.
`
`[0041] Note that as the compound semiconductor, a nitride
`semiconductor or a carbide semiconductor may be used
`other than the oxide semiconductor. Further, a semiconduc-
`tor having a light
`transmitting property with respect to
`visible light can also be used.
`
`In the present invention, crystallinity of a channel
`[0042]
`forming region of an oxide semiconductor film is made to be
`favorable by heating a gate electrode by LRTA. As a result,
`the oxide semiconductor film is only heated locally; conse-
`quently, most of a substrate is not heated, and a crystalliza-
`tion step can be performed as shrinking and bending of the
`substrate are controlled. Consequently, a semiconductor
`device including a semiconductor element with improved
`mobility characteristic can be manufactured as the step is
`simplified.
`
`[0043] Also, when forming a gate electrode over the
`substrate, forming an insulating film functioning as a gate
`insulating film over the gate electrode, forming a wiring
`having higher reflectivity with respect to a light source of
`LRTA than the gate electrode over the insulating film, and
`forming a oxide semiconductor film over the wiring, and
`then LRTA is performed towards a front surface or a rear
`surface of a substrate, the wiring is not heated as much as the
`gate electrode since it has higher reflectivity with respect to
`the light source of LRTA than the gate electrode. Therefore,
`a conductive film having a relatively low melting point such
`as copper, aluminum, or silver, which has low resistance, can
`be used for the wiring. As a result, an inexpensive semicon-
`ductor device can be provided.
`
`[0044] Also, unlike the amorphous silicon film, an insu-
`lating film does not form over a surface of the oxide
`semiconductor film due to oxidation even if the surface is
`
`exposed to an atmosphere containing oxygen. Therefore,
`even if the oxide semiconductor film is exposed to atmo-
`spheric air after formation, there is little change to the film.
`
`[0045] Further, when ZnO is used as the oxide semicon-
`ductor film, a heat treatment temperature in a crystallization
`step of the oxide semiconductor film can be around 350° C.
`or lower. This is because crystallization is sufliciently pro-
`moted for ZnO at a heat treatment temperature of around
`350° C. or lower. As a result, even if a resin substrate is used,
`shrinking of the substrate can be suppressed. Also, lamp
`heating is performed on the gate electrode using a material
`having lower reflectivity with respect to light emitted from
`a lamp than a source wiring and a drain wiring. Conse-
`quently, while crystallinity of at least a channel forming
`region of ZnO is improved due to heat conducted from the
`gate electrode, the source wiring and the drain wiring are not
`easily heated; therefore, a material having a relatively low
`melting point can be used for the source wiring and the drain
`wiring. For example, since a heat treatment temperature of
`350° C. or lower is suflicient when Al is used for the source
`
`wiring and the drain wiring, diffusion of Al to a semicon-
`ductor layer can be suppressed.
`
`[0046] As in the above, since a semiconductor device can
`be manufactured by a low temperature heat
`treatment
`(around 350° C. or lower), it is inexpensive as a process.
`BLUEHOUSE EXHIBIT 1005
`Page 26 of 48
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`US 2007/0072439 A1
`
`Mar. 29, 2007
`
`[0047] Further, since the oxide semiconductor has a light
`transmitting property, by forming the source electrode, the
`drain electrode, and the like with a conductive film having
`a light
`transmitting property and then forming a pixel
`electrode thereover, an aperture ratio of a pixel portion can
`be improved. When zinc oxide is used as the oxide semi-
`conductor, since resource of zinc oxide is more abundant
`than that of indium tin oxide (ITO) and since zinc oxide has
`lower resistance, a more inexpensive semiconductor device
`can be obtained by using zinc oxide instead of ITO as the
`pixel electrode. When silicon is used for a semiconductor
`film, in order to prevent the channel forming region from
`being irradiated with light, it is necessary to provide a light
`shielding film so as to overlap the channel forming region.
`As a result, a decrease in aperture ratio of a pixel portion is
`unavoidable. On the other hand, when zinc oxide is used for
`an oxide semiconductor film, since resource of zinc oxide is
`relatively abundant and since zinc oxide has a light trans-
`mitting property, by forming each of a source electrode, a
`drain electrode, and a pixel electrode using a transparent
`conductive material including indium tin oxide (ITO), ITSO
`made of indium tin oxide and silicon oxide, organic indium,
`organic tin, zinc oxide, titanium nitride, or the like each
`having a light transmitting property, a large scale display
`with high aperture ratio in a transmissive type display panel
`can be obtained. Also, light from a backlight can be effec-
`tively used to save power. For example, by sticking a display
`panel over a window of a building or a windshield of an
`automobile, a train, an airplane, or the like, a head-up
`display in which an image or text information is directly
`displayed can be realized.
`
`BRIEF DESCRIPTION OF DRAWINGS
`
`[0048]
`
`In the accompanying drawings:
`
`[0049] FIGS. 1A and 1B are each a cross-sectional view
`describing a manufacturing step of a semiconductor device
`relating to the present invention;
`
`[0050] FIG. 2 is a diagram describing temperature depen-
`dency of crystallization of an oxide semiconductor film of
`the present invention;
`
`[0051] FIGS. 3A to 3C are each a cross-sectional view
`describing a manufacturing step of a semiconductor device
`relating to the present invention;
`
`[0052] FIGS. 4A to 4H are each a cross-sectional view
`describing a manufacturing step of a semiconductor device
`relating to the present invention;
`
`[0053] FIGS. 5A to 5C are each a cross-sectional view
`describing a manufacturing step of a semiconductor device
`relating to the present invention;
`
`[0054] FIGS. 6A to 6F are each a cross-sectional view
`describing a manufacturing step of a semiconductor device
`relating to the present invention;
`
`[0055] FIG. 7 is a cross sectional-view of a semiconductor
`device relating to the present invention;
`
`[0056] FIGS. 8A to 8F are each a diagram showing a mode
`of a light emitting element relating to the present invention;
`
`[0057] FIGS. 9A to 9F are each a diagram describing a
`pixel circuit of a display panel relating to the present
`invention and an operation configuration thereof;
`
`[0058] FIGS. 10A to 10C are each a diagram describing
`mounting of a driver circuit relating to the present invention;
`
`FIG. 11 is a diagram describing a display module
`[0059]
`relating to the present invention;
`
`[0060] FIGS. 12A to 12F are each a diagram describing
`one example of an electronic appliance;
`
`[0061] FIGS. 13A and 13B are each a cross-sectional view
`of a semiconductor device relating to the present invention;
`
`[0062] FIGS. 14A and 14B are each a circuit diagram and
`a cross-sectional view of a pixel in a semiconductor device
`of the present invention;
`
`FIG. 15 is a cross-sectional view ofa semiconduc-
`[0063]
`tor device relating to the present invention;
`
`FIG. 16 is a diagram showing one mode of an
`[0064]
`element substrate in a semiconductor device of the present
`invention;
`
`[0065] FIGS. 17A and 17B are each a diagram showing
`one mode of an element substrate in a semiconductor device
`
`of the present invention;
`
`[0066] FIGS. 18A and 18B are each a block diagram
`showing a structur