JPH04360542A - Manufacture of thin film semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate the step-difference caused by a protective film and a wiring electrode, and make the film thickness of the wiring electrode thin by selectively depositing a metal electrode of aluminum or the like in an aperture part of the protecting film, in the forming process of an upper metal electrode of the source.drain or the like of a thin film semiconductor device. CONSTITUTION:An aperture is formed at a specified position of a protecting film 5 by a photolithography process. An N<+> layer 6 of ohmic contact is deposited on the whole surface by plasma CVD or the like, and left only in the aperture part by a photolithography process. By chemical vapor deposition method using alkyl aluminum hydride gas and hydrogen gas, aluminum is selectively deposited only in the aperture part, and source.drain electrodes 7, 8 are formed. Thereby aluminum is not deposited on a silicon nitride film of the insulative protective layer 5 and deposited only on the N<+> layer 6 left in the aperture part.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stably manufacturing thin film semiconductor devices such as thin film transistors and thin film transistor type optical sensors used in displays, image scanners, etc.

0002

[Prior art] Office automation (OA) in recent years
As a result, input/output devices such as displays and image scanners are becoming important as man-machine interfaces for office automation equipment such as word processors, personal computers, and facsimiles, and are required to be lightweight, thin, and low-priced.

From this perspective, thin film semiconductors such as hydrogenated amorphous silicon and polysilicon are formed on large-area insulating substrates to form active matrix type liquid crystal displays and optical sensors that form thin film transistors. The development of thin film semiconductor devices such as photoelectric conversion devices is progressing.

FIGS. 3A, 3B, and 3C each show an example of the structure of a conventional thin film transistor (hereinafter referred to as TFT) or a thin film semiconductor device such as a thin film transistor type optical sensor.

A gate insulating film 33 is deposited on the gate electrode 32 on the glass substrate 31, and a thin film semiconductor 34 that will become a channel, such as hydrogenated amorphous silicon (hereinafter referred to as a-Si:H), is deposited. Finally, a protective layer 35 is continuously deposited on the surface of this thin film semiconductor. Furthermore, an n+ layer 36 for ohmic contact between the semiconductor layer and the electrode metal, and source and drain electrodes 37 and 38 are provided at predetermined positions.
By forming a junction that has ohmic properties for electrons and blocking properties for holes, it operates as an n-channel transistor. 39 is a flattening protective film, and 40 is a wiring protective layer.

Note that the TFT shown in FIG. 3 is a thin film transistor type in which a stable photocurrent is obtained by controlling the distribution of photocarriers generated in a semiconductor layer by irradiating light between the source and drain electrodes with a gate electrode. It can also be applied as a light sensor.

FIG. 4 shows a method of manufacturing thin film semiconductor devices such as the conventional thin film transistor and thin film transistor type optical sensor shown in FIG.

In FIG. 4(a), 31 is a glass substrate;
32 is a Cr film serving as a gate electrode. Gate electrode 32
The Cr film was deposited over the entire surface with a thickness of 1000 Å by sputtering, etc., and by a photolithography process using a photosensitive resist.
Patterning is formed. Then, for example, plasma C
The silicon nitride film 33 that will become the gate insulating film is deposited using a VD method or the like.
000 Å, and the a-Si:H layer 34, which will become a semiconductor layer, has a thickness of 500 Å.
0 Å, protective layer 35 such as silicon nitride film 5000 Å,
Continuously deposited.

Next, in FIG. 4(b), after a predetermined position of the protective layer 35 is opened by a photolithography process, an ohmic contact n+ layer 36 of 1000 Å is deposited on the entire surface by plasma CVD or the like, and the source and drain layers are Electrode 3
7,38 aluminum to 1000 by sputtering method etc.
0 Å, showing that it was deposited on the entire surface.

Next, FIG. 4C shows the state after the source and drain electrodes 37 and 38 and the unnecessary portions of the ohmic contact n+ layer 36 have been successively etched by a photolithography process.

Next, in FIG. 4(d), the TFTs are separated by a photolithography process. In order to protect the wiring of these TFTs from corrosion, a wiring protection layer 40 of silicon nitride or the like is formed over the entire surface of the TFT shown in FIG. 3(a).
is obtained.

In addition, in consideration of flattening the steps formed by the TFT electrodes, the flattening protective film 3 is made of, for example, a polyimide resin film polymerized by heat treatment, instead of silicon nitride.
9, the TFT of FIG. 3(b) is completed.

Further, in consideration of safety, a wiring protection layer 40 such as a silicon nitride film is formed on the flattening protection film 39 such as a polyimide resin film, resulting in the TFT shown in FIG. 3(c).

[0014]

[Problems to be Solved by the Invention] Thin film semiconductor devices such as thin film transistors formed by the conventional method as shown in FIG. These impurities must be completely blocked by a protective layer. Furthermore, aluminum used for wiring such as electrodes is also corroded by moisture, which causes wire breakage and an increase in wiring resistance.

[0015] If the protective layer is insufficient as described above, it will be a serious problem when it is actually applied to products such as long contact type reading sensors for facsimile machines and active matrix type liquid crystal displays. For example, with an active matrix display, the appearance changes dramatically. In addition, the basic characteristics of sensors, photocurrent and dark current, are
It is unstable and causes major deterioration of the read image.

In the conventional method, a protective layer is formed using two or more layers of silicon nitride film and polyimide resin, but this is flattened by the polyimide resin film, and moisture is blocked by the silicon nitride film. This is due to the functional separation of each membrane. Polyimide resin alone is insufficient to block moisture, and silicon nitride film alone is sufficient to block moisture, but flattening is difficult.

However, in this conventional method, the process of forming the protective film is complicated and the manufacturing cost increases. Furthermore, as substrates become larger and wiring becomes finer in the future, there will be limits to flattening using polyimide resin, which will lower manufacturing yields. Furthermore, since self-alignment is impossible, a large space margin between electrodes is required, which also makes miniaturization difficult.

[0018]

[Means and operations for solving the problems] According to the present invention, as a solution to the problems of the prior art as described above,
A metal gate electrode and a gate insulating film are formed on an insulating substrate, a semiconductor layer and an insulating protective film are laminated on the gate insulating film, and the semiconductor layer and the insulating protective film are formed through an opening formed in the insulating protective film. A method for manufacturing a thin film semiconductor device in which a pair of metal electrodes are formed on a semiconductor layer via an ohmic contact layer, including the step of selectively forming a metal electrode in an opening of the insulating protective film. A method for manufacturing a thin film semiconductor device is provided.

Here, as the step of forming the metal electrode, a step of selectively forming aluminum by a chemical vapor deposition method using alkyl aluminum hydride gas and hydrogen gas can be used.

Thus, according to the present invention, in the method for manufacturing a thin film semiconductor device such as a thin film transistor, the source and drain electrodes are selectively deposited in the openings of the insulating protective film. , there is no difference in level between the drain electrode and the protective film, and the thickness of the source and drain electrodes can be reduced. Furthermore, since the protective film for the wiring can be formed flat, polyimide resin for flattening is not required, which reduces manufacturing costs and improves manufacturing yield.

[0021]

EXAMPLES The present invention will be explained below based on examples.

(Embodiment 1) FIG. 1 shows an example of the structure of a thin film semiconductor device such as a thin film transistor (hereinafter referred to as TFT) or a TFT type optical sensor according to the present invention. Below, Figure 2
1, a method for manufacturing thin film semiconductor devices such as TFTs and TFT-type photosensors according to the present invention shown in FIG. 1 will be described.

In FIG. 2(a), 1 is a glass substrate, 2
is a Cr film serving as a gate electrode. Cr of gate electrode 2
The film is deposited over the entire surface to a thickness of 1000 Å by sputtering or the like, and patterned by a photolithography process using a photosensitive resist. Thereafter, a silicon nitride film 3 that will become a gate insulating film is formed with a thickness of 3000 Å using, for example, a plasma CVD method.
An a-Si:H layer 4 serving as a semiconductor layer is successively deposited to a thickness of 5000 Å, and a protective layer 5 such as a silicon nitride film is deposited to a thickness of 5000 Å.

Next, in FIG. 2(b), after a predetermined position of the protective layer 5 is opened by a photolithography process, an ohmic contact n+ layer 6 of 1000 Å is deposited on the entire surface by plasma CVD or the like, and then a photolithography process is performed. This leaves the n+ layer 6 only in the opening.

Next, as shown in FIG. 2(c), aluminum is selectively deposited to a thickness of 5000 Å only in the openings by chemical vapor deposition using alkyl aluminum hydride gas and hydrogen gas. The state where electrodes 7 and 8 are formed is shown. According to this method, aluminum is not deposited on the silicon nitride film of the insulating protective layer 5, but is deposited only on the n+ layer 6 left in the opening in FIG. 2(b).

This method will be described in more detail. FIG. 12 shows a metal film forming apparatus suitable for selectively depositing aluminum in the openings as described above.

As shown in FIG. 12, this continuous metal film forming apparatus includes load lock chambers 111 and C, which are connected to each other by a gate valve 110 so as to be able to communicate with each other while being shut off from outside air.
It is composed of a VD reaction chamber (first film forming chamber) 112, an RF etching chamber 113, a sputtering chamber (second film forming chamber) 114, and a load lock chamber 115, and each chamber is equipped with an exhaust system 116a to 116e. It is configured to be evacuated or depressurized by. The load lock chamber 111 is a chamber in which the atmosphere of the substrate before the deposition process is evacuated and then replaced with an H2 atmosphere in order to improve throughput. The next CVD reaction chamber 112 is a chamber in which selective deposition is performed on a substrate under normal pressure or reduced pressure, and a resistance heating element (200 to 430
A substrate holder 118 having a substrate holder 117 (heated to .degree. 130 is a heating lamp, and 131 is a claw for fixing the base. The next RF etching chamber 113 is a chamber in which cleaning (etching) the surface of the substrate after selective deposition is performed in an Ar atmosphere. An Ar gas supply line 122 is connected thereto. The next sputtering chamber 114 is a chamber in which a metal film is non-selectively deposited on the substrate surface by sputtering in an Ar atmosphere.
A substrate holder 123 heated to .degree. C. and a target electrode 124 to which a sputter target material 124a is attached are provided, and an Ar gas supply line 125 is connected thereto. The final load lock chamber 115 is an adjustment chamber before the substrate is exposed to the outside air after metal film deposition is completed, and the atmosphere is changed to N2.
is configured to be replaced by

[0028] In this way, the substrate can be sequentially moved from the load lock chamber 111 to the CVD chamber 112, the RF etching chamber 113, the sputtering chamber 114, and the load lock chamber 115 according to the process without being exposed to the outside air. It looks like this.

Specifically, the metal film that can be formed according to the present invention includes a combination of selectively deposited Al and non-selectively deposited Al, a combination of Al and Al-Si, and a combination of Al and Al.
These include a combination with l-Cu, a combination of Al and Al-Si-Cu, a combination of Al and Al-Ti, etc.

The surface temperature of the substrate during selective Al deposition is higher than the decomposition temperature of alkyl aluminum hydride4.
The temperature is preferably less than 50°C, more preferably 260°C or more and 440°C or less. In particular, if monomethylaluminum hydride (MMAH) or dimethylaluminum hydride (DMAH) is used as the raw material gas, H2 gas is used as the reaction gas, and the substrate surface is lamp heated under a mixture of these gases, a high deposition rate can be achieved. A high quality Al film can be formed using this method. In this case, A
The substrate surface temperature during film formation is more preferably 260°C.
By setting the temperature to ~440° C., a high quality film can be obtained at a high deposition rate of 3000 to 5000 Å/min, which is higher than in the case of resistance heating.

Examples of the direct heating method (energy from the heating means is directly transmitted to the substrate to heat the substrate itself) applicable to the present invention include lamp heating using a halogen lamp, a xenon lamp, or the like. Further, as resistance heating, a heating element is provided on a substrate support member disposed in a space for forming a deposited film for supporting a substrate on which a deposited film is to be formed.

A deposited in the opening by the method described above
l has a single crystal structure and has excellent properties in (1) reducing the probability of hillock occurrence and (2) reducing the probability of alloy spike occurrence. Since the method described above is a deposition method with excellent selectivity, a non-selective deposition method is applied as the next deposition step, and Al is deposited on the selectively deposited Al film and SiO2, which is an insulating film. By forming a metal film containing as a main component, a metal film suitable for wiring of a semiconductor device can be obtained.

The procedure for forming an Al film on a substrate as shown in FIG. 2(b) is as follows.

First, the above-mentioned base body is placed in the load lock chamber 111.
Place it in As described above, hydrogen is introduced into the load lock chamber 111 to create a hydrogen atmosphere. Then, the inside of the reaction chamber 112 is approximately 1×10-8 by the exhaust system 116b.
Exhaust to Torr. However, even if the degree of vacuum in the reaction chamber 112 is worse than 1.times.10@-8 Torr, Al can be formed into a film.

DMAH is then supplied from the gas line 119. H2 is used as the carrier gas for the DMAH line. A second gas line (not shown) carries H as a reaction gas.
2, H2 is flowed from this second gas line, and the opening degree of a slow leak valve (not shown) is adjusted to bring the pressure inside the reaction chamber 112 to a predetermined value. Typical pressure in this case is about 1.5 Torr. DM from DMAH line
AH is introduced into the reaction chamber. The total pressure is approximately 1.5 Torr, and the DMAH partial pressure is approximately 5.0×10 −3 Torr. Thereafter, electricity is applied to the resistance heating element of the substrate holder 118 to directly heat the wafer. In this way, Al is deposited. The temperature of the substrate surface at this time was 260°C.

In FIG. 2(d), a second protective layer 10 made of silicon nitride or the like is formed to a thickness of 3000 Å on the entire surface by performing element isolation using a photolithography process, and the T of FIG.
FT is completed.

FIG. 5 shows the stability of the thin film transistor manufactured by the manufacturing method of the present invention and the thin film transistor manufactured by the conventional manufacturing method, and shows the incidence of corrosion of aluminum in the source and drain electrodes with respect to the exposure time at high temperature and high humidity. According to this, in the case of the manufacturing method of the present invention shown in FIG. 1 and the case of the conventional method shown in FIG. In the cases of FIGS. 3(a) and 3(b), a lot of corrosion occurs in the wiring. This is because when only polyimide resin is used for the protective film, the moisture resistance of the polyimide resin is poor, and when only silicon nitride is used for the protective film, moisture enters through the step portion due to poor step coverage.

As mentioned above, conventional FIGS. 3(a) and 3(b)
Since the manufacturing method shown in Figure 3(c) resulted in corrosion of the wiring and insufficient moisture resistance, a complicated method was used as shown in Figure 3(c), which reduced the manufacturing cost in the process of forming the protective film. was increasing and the yield was decreasing. However, according to the method of the present invention, moisture resistance can be maintained by a simple method with an extremely low incidence of corrosion equivalent to the conventional method shown in FIG. 3(c).

In this embodiment, a thin film transistor using amorphous silicon has been described, but the present invention can also be applied to a thin film transistor using polysilicon or other thin film compound semiconductors instead of amorphous silicon. Moreover, as an insulating protective film used for selectively depositing these semiconductors, an insulating film of silicon oxide, silicon carbide, or the like can be used instead of silicon nitride.

(Example 2) When the thin film semiconductor devices such as thin film transistors described in Example 1 are actually applied to active matrix liquid crystal displays, contact type reading sensors, etc., a plurality of them are integrated on a substrate. be done. In that case, the lower wiring of the gate electrode and the upper wiring of the source and drain electrodes are electrically connected to form a matrix wiring structure and connected to, for example, an external IC. At that time, a step is required to connect the upper wiring and the lower wiring, and heretofore, a level difference in the wiring occurs, but the present invention can also be applied to the manufacturing process of such a semiconductor device. A thin film semiconductor device as an application example thereof is shown in FIG. 6 as a second embodiment of the present invention. A process diagram showing the manufacturing method is shown in FIG.

In FIG. 7(a), 1 is a glass substrate, 2
is a Cr film serving as a gate electrode. Cr of gate electrode 2
The film is deposited over the entire surface to a thickness of 1000 Å by sputtering or the like, and patterned by a photolithography process using a photosensitive resist. Thereafter, a silicon nitride film 3 that will become a gate insulating film is formed with a thickness of 3000 Å using, for example, a plasma CVD method.
An a-Si:H layer 4 serving as a semiconductor layer is successively deposited to a thickness of 5000 Å, and a protective layer 5 such as a silicon nitride film is deposited to a thickness of 5000 Å.

Next, FIG. 7(b) shows the lower gate electrode opened at a predetermined position by a photolithography process to expose the lower gate electrode in order to connect to the upper electrode.

Next, FIG. 7(c) shows a silicon nitride film 3 and a semiconductor layer formed by chemical vapor deposition using alkyl aluminum hydride gas and hydrogen gas in the same manner as in the first embodiment. This shows that aluminum was deposited to a thickness of 8000 Å, which is equivalent to the sum of the film thicknesses of No. 4. As in the first embodiment, aluminum is not deposited on the silicon nitride film of the protective layer 5, but aluminum is selectively deposited only on the opened gate electrode.

Next, in FIG. 7(d), after opening the protective layer 5 at a predetermined position by a photolithography process, an ohmic contact n+ layer 6 of 1000 Å is deposited on the entire surface by plasma CVD or the like, and then a photolithography process is performed. The n+ layer 6 is left in a part of the opening.

Next, FIG. 7(e) shows aluminum deposited to a thickness of 5000 Å by chemical vapor deposition using alkyl aluminum hydride gas and hydrogen gas in the same manner as in the first embodiment. shows. As in the first embodiment, aluminum is not deposited on the silicon nitride film of the protective layer 5, but is selectively deposited only on the deposited aluminum in FIG. 7(c) and in the openings in FIG. 7(d). The source and drain electrodes 7 and 8 are formed, and the source electrode 7 and the lower electrode 2 are connected. In this way, the electrode 7,
8 and the protective layer 5 can be eliminated.

Next, in FIG. 7(f), element isolation is performed by a photolithography process, and a second protective layer 10 of silicon nitride or the like is formed to a thickness of 3000 Å over the entire surface, and the book shown in FIG. 6(a) is formed. A semiconductor device according to a second embodiment of the invention is completed.

In the future, when wiring width becomes finer and further reduction in contact resistance is required, by using a metal film forming apparatus as shown in FIG. After selectively depositing aluminum in the sputtering chamber (second film forming chamber) 112,
It is also possible to add a method in which non-selectively deposited aluminum is deposited on the entire surface to a thickness of about 1000 Å using No. 14, and a fine pattern is formed by a photolithography process. FIG. 6(b) shows a sectional view formed in this manner as a further application example of the second embodiment of the present invention.

FIG. 8 shows a cross-sectional view of a thin film semiconductor device according to an embodiment of the present invention applied to an image reading device such as a facsimile machine. Incident light from the light source 72 is reflected by the original 69 and is photoelectrically converted by the thin film transistor photosensor created in the process shown in FIGS. Accumulated. Furthermore, these charges are transferred and reset by thin film transistors manufactured in the same process. Figure 9
4 shows a cross-sectional view of a contact type image reading device formed from a thin film semiconductor device manufactured by a conventional manufacturing method as shown in FIG. In the device shown in FIG. 9 produced by the conventional method, the difference in level between the upper electrode and the protective layer is larger than in the device shown in FIG. The structure is as follows. In addition, in these figures,
70 is an anti-wear layer, and 71 is an adhesive layer.

FIG. 10 shows an example of a plan view of a circuit of a thin film transistor type optical sensor of the present invention and a complete contact type sensor constructed of thin film transistors. In the same figure, 2
0 is a gate drive wiring section formed in a matrix, 21 is a photosensor section using a thin film transistor type photosensor according to the present invention, 22 is a charge storage section, 23 is a transfer switch using a thin film transistor according to the present invention, and 24 is a charge transfer switch. A discharge switch using a thin film transistor according to the present invention resets the charge in the storage section 22, 25 is a lead line connecting the signal output of the transfer switch to a signal processing IC, and 26 is a light incidence window. In this embodiment, an a-Si:H film is used as the photoconductive semiconductor layer constituting the optical sensor section 21, the transfer switch 23, and the discharge switch 24, and a silicon nitride film produced by plasma CVD is used as the insulating layer. There is.

In FIG. 10, in order to avoid complexity, only the upper and lower two layers of electrode wiring are shown, and the photoconductive semiconductor layer and the insulating layer are not shown. Further, an n+ layer is formed at the interface between the upper layer electrode wiring and the semiconductor layer to form an ohmic contact.

FIG. 11 shows an equivalent circuit of the thin film transistor type optical sensor of the present invention and the circuit of a complete contact type sensor constructed from thin film transistors. In the figure, Si,
1, Si, 2, Si, 3...Si,N are optical sensors that constitute the optical sensor section 21 in FIG. 10, i is the block number, and 1 to N are the bits in the block. number (hereinafter referred to as Si,n). In the same figure, Ci,n is a capacitor of the charge storage section 22, which stores photocurrents corresponding to the optical sensors Si,n. Further, the transistor STi,n of the transfer switch 23 for transferring the charge of the storage capacitor Ci,n to the load capacitor CXn and the transistor SRi,n of the discharging switch 24 for resetting the charge correspond similarly.

These optical sensor Si,n, storage capacitor Ci,n, transfer switch transistor STi
,n, and the discharge switch transistor SRi,n
are arranged in an array in a line, N pieces constitute one block, and the whole is divided into M blocks. For example, if the number of sensors is 1728, N=32 and M=54. The gate electrodes of the transfer switches STi,n and discharge switches SRi,n provided in an array are connected to the gate wiring section. The gate electrodes of the transfer switches STi,n are commonly connected in the first block, and the gate electrodes of the discharge switches SRi,n are connected to the gate electrodes of the transfer switches in the next block.

The common lines (gate drive lines G1, G2, G3, . . . GM) of the matrix wiring section 20 are driven by a gate drive section 246. On the other hand, the signal outputs are connected to the signal processing section 247 via lead lines 25 (signal output lines D1, D2, D3, . . . DN) having a matrix configuration. In addition, the optical sensor Si,
The gate electrode of n is connected to the driving unit 250 and a negative bias is applied thereto.

In this configuration, the gate drive line G1
, G2, G3...GM has a gate drive section 2.
Sequential selection pulses (VG1, VG2, VG3
...VGM) is supplied. First, when the gate drive line G1 is selected, the transfer switch ST1,1
~ST1,N becomes ON state, storage capacitor C1
, 1 to C1,N are transferred to the load capacitors CX1 to CXN.

Next, when the gate drive line G2 is selected, the transfer switches ST2,1 to ST2,N are turned on, and the charges accumulated in the storage capacitors C2,1 to C2,N are transferred to the load capacitors CX1 to CX1. CXN, and at the same time discharge switches SR1,1 to SR1,N
As a result, the charges in the storage capacitors C1,1 to C1,N are reset. Similarly, the gate drive line G3
, G4, G5, . . . GM are also selected and read operations are performed. These operations are performed for each block, and the signal outputs VX1, VX of each block
2, VX3...VXN is the signal processing section 247
The signals are sent to the inputs D1, D2, D3, . . . DN, and are converted into serial signals and output.

As an application example of the thin film semiconductor device of the present invention,
Here, as shown in FIG. 8, a wear-resistant layer 7 is placed on the top of the optical sensor.
0 and illuminated by a light source 72 from the back side of the sensor,
Although we have only described a lensless fully contact type image reading device that reads the original 69, it can also be applied to a contact type image reading device using a 1-magnification imaging lens (for example, a SELFOC lens manufactured by Nippon Sheet Glass Co., Ltd.). can. It goes without saying that the present invention can be applied not only to contact type image reading devices but also to active matrix type liquid crystal displays.

[0057]

Effects of the Invention The present invention provides a method for selectively depositing metal electrodes such as aluminum in openings of a protective film in the process of forming upper metal electrodes such as sources and drains of thin film semiconductor devices such as thin film transistors and thin film transistor photosensors. By doing so, the difference in level between the protective film and the wiring electrode was eliminated, and the thickness of the wiring electrode could be reduced. Furthermore, the polyimide resin coating conventionally used for planarization is no longer necessary, and the process for forming the wiring protection film can be greatly simplified. This lowered manufacturing costs and improved manufacturing yields.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a thin film transistor according to a first embodiment of the present invention.

FIG. 2 is a process diagram showing a method for manufacturing a thin film transistor according to a first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional thin film transistor.

FIG. 4 is a process diagram showing a conventional thin film transistor manufacturing method.

FIG. 5 is a diagram showing the corrosion incidence rate of wiring with respect to the exposure time at high temperature and high humidity.

FIG. 6 is a sectional view of a thin film semiconductor device according to a second embodiment of the present invention.

FIG. 7 is a process diagram showing a method for manufacturing a thin film semiconductor device according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a contact type image reading device using a thin film semiconductor device manufactured by the manufacturing method of the present invention.

FIG. 9 is a cross-sectional view of a contact type image reading device using a thin film semiconductor device manufactured by a conventional manufacturing method.

FIG. 10 is a plan view of a contact type image reading device using a thin film semiconductor device according to the present invention.

FIG. 11 is an equivalent circuit diagram of a contact type reader using a thin film semiconductor device according to the present invention.

FIG. 12 is a schematic diagram of a metal film forming apparatus used to create a thin film semiconductor device according to the present invention.

[Explanation of symbols]

1, 31 Glass substrate 2, 32 Gate electrode 3, 33 Gate insulating film (silicon nitride film) 4,
34 Semiconductor film (amorphous silicon film) 5,
35 First protective layer (silicon nitride film) 6, 36
n+ layer (ohmic contact layer) 7, 37
Source electrode layer (upper electrode layer) 8, 38
Drain electrode layer (upper electrode layer) 39 Flattening protective film (polyimide resin film) 10, 40 Wiring protective layer (silicon nitride film) 69 Original 70 Wear-resistant layer 71 Adhesive layer 72 Light source 20 Gate wiring section 21 formed in matrix
Optical sensor section 22 Charge storage section 23 Transfer switch 24 Discharge switch 25 Signal output lead line 26 Light incidence window 246 Gate drive section 247 Signal processing section 250 Sensor gate drive section Si,n Photosensor Ci,n Storage capacitor CXn Load Capacitor STi,n Transfer switching transistor SRi,n Reset switching transistor 110 Gate valve 111, 115 Load lock chamber 112
CVD reaction chamber 113 RF etching chamber 114 Sputtering chamber 116a, 116b, 116c, 116d, 116e
Exhaust system 117 Resistance heating element 118 CVD substrate holder 119 CVD gas introduction line 120
RF etching substrate holder 121 RF etching electrode 122 RF etching Ar supply line 123
Sputtering substrate holder 124 Sputtering target electrode 124a Sputtering target material 125 Sputtering Ar supply line 130 Lamp 131 Claw

Claims (2)

[Claims] Claim 1: A metal gate electrode and a gate insulating film are formed on an insulating substrate, a semiconductor layer and an insulating protective film are laminated on the gate insulating film, and a metal gate electrode and a gate insulating film are formed on the insulating protective film. In the method for manufacturing a thin film semiconductor device in which a pair of metal electrodes are formed on the semiconductor layer via an ohmic contact layer through an opening in the insulating protective film, a metal electrode is selectively formed in the opening in the insulating protective film. A method for manufacturing a thin film semiconductor device, the method comprising the step of: 2. The thin film semiconductor according to claim 1, wherein the step of forming the metal electrode comprises selectively forming aluminum by a chemical vapor deposition method using an alkyl aluminum hydride gas and hydrogen gas. Method of manufacturing the device.