JPH05160152A - Manufacture of film transistor - Google Patents

Abstract

PURPOSE:To form a gate insulating film high in closeness and large in breakdown strength and an operation semiconductor film excellent in closeness with the gate insulating film and excellent in film quality concerning the manufacture of a film transistor. CONSTITUTION:In the manufacture of a film transistor which has a gate electrode 2, a gate insulating film 3, an operation semiconductor film 4, and a channel protective layer 5 stacked in order on an insulating substrate 1, and a source electrode 7a and a drain electrode 7b arranged on both sides of the channel protective layer 5, this is so constituted as to form the gate insulating film 3 by an atom layer epitaxy method, and subsequently form the operation semiconductor film 4 by atom layer epitaxy method. Moreover, at formation of the gate insulating film 3, this is so constituted as to grow a compound insulator by the atomic layer epitaxy method, which exposes the insulating substrate 1 several times alternately in alkyl amine alane atmosphere and atmosphere including oxygen, and form all or one part of the gate insulating film 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin film transistor. In recent years, a thin film transistor (hereinafter referred to as TFT) matrix has been used as a driving element for a liquid crystal display panel, electroluminescence and the like. In such a TFT matrix, it is necessary to manufacture hundreds of thousands of TFTs so as not to cause defects on the display screen. Therefore, individual TFT
There is a strong demand for a manufacturing method that does not cause defects in the.

[0002]

2. Description of the Related Art In an active matrix drive type liquid crystal display panel, TFTs are arranged in a matrix corresponding to individual pixels for dot display, so that each pixel has a memory function and has a high contrast. The line can be displayed.

In such a liquid crystal display panel, a large number of gate bus lines and drain bus lines are arranged in the X and Y directions, respectively, and a driving voltage is sequentially applied to each of these bus lines to form a gate bus line. By selectively driving a TFT arranged near the intersection of the line and the drain bus line, a desired pixel is displayed in dots.

FIG. 5 is a sectional view of a TFT, in which 1 is a glass substrate, 2 is a gate electrode, 3 is a gate insulating film, 4 is an operating semiconductor film, 5 is a channel protective layer, 6a is a source, 6b is a drain, and 7a. Is a source electrode, 7b is a drain electrode, 8 is a pixel electrode, 9 is a drain bus line, and 10 is a surface protective film.

The outline of the conventional process is as follows.
After the gate electrode 2 is formed on the glass substrate 1, a SiN _x film serving as a gate insulating film 3, an amorphous Si (a-Si) film serving as an operating semiconductor film 4, and a channel protective layer 5 are formed by a plasma CVD method. SiO ₂ films are sequentially formed. The SiO ₂ film is etched using the mask, and S is formed on the gate electrode 2.
The channel protective layer 5 is formed while leaving the iO ₂ film.

After the n ⁺ type a-Si film is deposited by the plasma CVD method and then the Ti film is deposited by the sputtering method, the Ti film, the n ⁺ type a-Si film and the a-S film are formed by using a mask.
The i film 4 is etched to form a source 6a and a drain 6b made of an n ⁺ -type a-Si film, and a source electrode 7a and a drain electrode 7b made of a Ti film.

After depositing an ITO film on the entire surface by a sputtering method, the ITO film is etched using a mask to form a source electrode.
The pixel electrode 8 connected to 7a is formed. After depositing an Al film on the entire surface by sputtering, it is etched using a mask to form a drain bus line 9 connected to the drain electrode 7b.

After that, a surface protection film 10 of SiN _x is formed on the entire surface by, for example, the plasma CVD method. In order to avoid the influence of the liquid crystal cell capacitance without adding the auxiliary capacitance, the overlap margin between the gate electrode 2 and the source / drain electrodes 7a, 7b is made small. The stress concentrates on the gate insulating film 3. If the mechanical strength of the gate insulating film 3 is small, cracks will occur there, making it difficult to obtain a sufficient withstand voltage or insulation resistance.

When a short circuit occurs due to dielectric breakdown, not only a point pixel defect due to defective operation of a display cell but also a line defect that is fatal in display occurs. In addition, even if the short circuit does not occur, when the defect has a low resistance, a point defect occurs due to leakage of charges accumulated in the liquid crystal cell.

The gate insulating film formed by the plasma CVD method is not sufficiently dense and does not necessarily have sufficient mechanical strength. In order to improve the reliability of the gate insulating film, it is known to form an alumina or tantalum oxide gate insulating film using an alcoholate as a raw material on the gate electrode by an atomic layer epitaxy method (for example, JP-A-1-179423). Bulletin).

The gate insulating film formed by the atomic layer epitaxy method has high denseness and high mechanical strength. In this case, however, it is difficult to completely remove abnormal growth nuclei at the stepped portion at the end of the lower gate electrode, and it is low. Resistance defects are likely to occur, and it is often difficult to manufacture a display panel without any point defects.

When the gate insulating film is formed by the atomic layer epitaxy method and then the operating semiconductor film is formed thereon, the glass substrate is once taken out from the atomic layer epitaxy apparatus and then placed in the plasma CVD apparatus. To deposit the operating semiconductor film. This causes the interface between the gate insulating film and the operating semiconductor film to be contaminated, and also reduces the adhesion between the gate insulating film and the operating semiconductor film.
There is also a problem that the FT characteristic is deteriorated.

Furthermore, since the channel protective layer and the surface insulating film deposited by the plasma CVD method are not sufficiently dense, it is often impossible to obtain sufficient mechanical strength and sufficient withstand voltage or insulation resistance.

[0014]

SUMMARY OF THE INVENTION In order to solve the various problems described above, the present invention increases the denseness of the gate insulating film to increase the mechanical strength, increases the withstand voltage and the insulation resistance, and further It is an object of the present invention to provide a method for improving the adhesiveness between an insulating film and an operating semiconductor film and improving the characteristics of the operating semiconductor film.

It is another object of the present invention to provide a method for increasing the denseness of the channel protective layer and the surface insulating film to increase the mechanical strength and increase the withstand voltage and the insulation resistance.

[0016]

1 (a) to 1 (e) are sectional views in order of steps for explaining an embodiment, and FIGS. 2 (a) to 2 (e) are for explaining another embodiment. FIG. 3 is a perspective view of an atomic layer epitaxy apparatus, and FIG. 4 is a schematic view of another atomic layer epitaxy apparatus.

The above-mentioned problem is solved by the following problems: the gate electrode 2, the gate insulating film 3, the operating semiconductor film 4, and the gate electrode 2, which are sequentially stacked on the insulating substrate 1.
In manufacturing a thin film transistor having a channel protective layer 5 and a source electrode 7a and a drain electrode 7b arranged on both sides of the channel protective layer 5, a gate insulating film 3 is formed by an atomic layer epitaxy method, and then an atomic layer is formed. This is solved by a method of manufacturing a thin film transistor in which the operating semiconductor film 4 is formed by an epitaxy method.

In forming the operating semiconductor film 4,
The first step of exposing the insulating substrate 1 to the atmosphere containing the first source material gas to adsorb the first source material gas to the insulating substrate 1 and the plasma atmosphere containing the second source material gas Atom that exposes the insulating substrate 1 and causes the second source material to react with the first source material adsorbed on the insulating substrate 1 to form a semiconductor, and repeats the cycle of the second step a plurality of times. This is solved by a method of manufacturing a thin film transistor in which the operating semiconductor film 4 is formed by a layer epitaxy method.

In forming the operating semiconductor film 4,
A first step of exposing the insulating substrate 1 to an atmosphere containing a first source material gas to adsorb the first source material gas to the insulating substrate 1; and insulating into an atmosphere containing a second source material gas Second step of exposing the insulating substrate 1 to adsorb the second raw material gas to the insulating substrate 1, and exposing the insulating substrate 1 to a plasma atmosphere to adsorb the first raw material adsorbed This is solved by a method of manufacturing a thin film transistor in which the operating semiconductor film 4 is formed by an atomic layer epitaxy method in which the cycle of the third step of reacting the second source material to form a semiconductor is repeated a plurality of times.

In forming the operating semiconductor film 4,
A first step of exposing the insulating substrate 1 to an atmosphere containing a first source material gas to adsorb the first source material gas to the insulating substrate 1; and exposing the insulating substrate 1 to a plasma atmosphere Second, which decomposes and modifies the adsorbed first raw material
And a cycle of a third step of exposing the insulating substrate 1 to an atmosphere containing a second source material gas and reacting the second source material with the modified first source material to form a semiconductor. This is solved by a method of manufacturing a thin film transistor in which the operating semiconductor film 4 is formed by an atomic layer epitaxy method that is repeated a plurality of times.

In forming the operating semiconductor film 4,
A first step of exposing the insulating substrate 1 to an atmosphere containing a raw material gas to adsorb the raw material gas to the insulating substrate 1; and exposing the insulating substrate 1 to a plasma atmosphere to decompose the raw material This is solved by a method of manufacturing a thin film transistor in which the operating semiconductor film 4 is formed by an atomic layer epitaxy method in which the cycle of the second step of forming a semiconductor is repeated a plurality of times.

Further, the gate electrode 2, the gate insulating film 3, the operating semiconductor film 4, the channel protective layer 5 and the source electrodes 7a disposed on both sides of the channel protective layer 5 are sequentially laminated on the insulating substrate 1. In the production of the thin film transistor having the drain electrode 7b and the
Manufacture of a thin film transistor in which a compound insulator is formed by an atomic layer epitaxy method in which the insulating substrate 1 is alternately exposed to an alkylamine alane atmosphere and an oxygen-containing atmosphere a plurality of times to form all or part of the gate insulating film 3. Solved by the method.

Further, the gate electrode 2, the gate insulating film 3, the operating semiconductor film 4, the channel protection layer 5 and the source electrodes 7a disposed on both sides of the channel protection layer 5 are sequentially stacked on the insulating substrate 1. In manufacturing a thin film transistor having a drain electrode 7b and a drain electrode 7b, a compound insulator is formed by an atomic layer epitaxy method in which the insulating substrate 1 is alternately exposed to an alkylamine alane atmosphere and an oxygen-containing atmosphere when forming the channel protective layer 5. To form the channel protective layer 5
Is solved by a method for manufacturing a thin film transistor that forms all or part of the above.

Further, the gate electrode 2, the gate insulating film 3, the operating semiconductor film 4, the channel protective layer 5 and the source electrodes 7a disposed on both sides of the channel protective layer 5 are sequentially laminated on the insulating substrate 1. In manufacturing a thin film transistor having a drain electrode 7b and a surface protective film 10, the surface protective film
When forming 10, a compound insulator is formed by an atomic layer epitaxy method in which the insulating substrate 1 is alternately exposed to an alkylamine alane atmosphere and an atmosphere containing oxygen a plurality of times, and all or part of the surface protective film 10 is formed. This is solved by a method of manufacturing a thin film transistor to be formed.

[0025]

According to the present invention, when the thin film transistor is manufactured, the gate insulating film 3 is formed by the atomic layer epitaxy method, and then the operating semiconductor film 4 is formed by the atomic layer epitaxy method. The film 4 can also be formed as a highly dense film. Moreover, since it is not necessary to take out the substrate to the outside while the formation of the gate insulating film 3 is completed and the formation of the operating semiconductor film 4 is started, there are problems such as a decrease in adhesion between the gate insulating film 3 and the operating semiconductor film 4 and contamination. Does not happen.

The formation of the operating semiconductor film 4 by the atomic layer epitaxy method can be performed by a cycle of exposing the substrate to various source material gas atmospheres and exposing it to a plasma atmosphere.

When alkylamine alane is used as a raw material for forming a gate insulating film, a channel protective layer, or a surface protective film by the atomic layer epitaxy method, a high-purity insulating film having high density and no carbon contamination can be obtained. It is possible to form an insulating film having excellent mechanical properties and high withstand voltage and insulation resistance. Such an insulating film formed by the atomic layer epitaxy method is also effective when formed on a part of the gate insulating film, the channel protective layer or the surface protective film.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 (a) to 1 (e) are process sectional views for explaining an embodiment, and FIGS. 2 (a) to 2 (e) are process sectional views for explaining another embodiment. FIG. 3 is a perspective view of an atomic layer epitaxy apparatus, and FIG. 4 is a schematic view of another atomic layer epitaxy apparatus.

An embodiment of the present invention will be described below with reference to these drawings. First Embodiment Refer to FIG. 1 (a). For example, an NA40 glass substrate is used as a glass substrate 1, a Ti film having a thickness of, for example, 1000 Å is sputtered thereon, and the Ti film is etched using a mask to form a gate electrode 2.
To form.

Referring to FIG. 1B, the gate insulating film 3 is formed by the atomic layer epitaxy method. FIG. 3 is a perspective view of the atomic layer epitaxy apparatus.
Is a glass substrate, 11 is a first source material gas, 12 is a second source material gas, 13 is a barrier gas, C is a reaction chamber, V _{0 to} V ₄
The _{valve, N a, N b, N} c is the gas inlet port, PC plasma cathode, RF high frequency power, OF orifice valve, V
P represents a turbo molecular pump. This atomic layer epitaxy apparatus is an improvement of the previously disclosed atomic layer epitaxial apparatus (see, for example, Japanese Patent Laid-Open No. 2-74029), in which a high frequency is applied to a region to which the second source material gas is supplied to generate plasma. I am trying to do it.

First, the glass substrate 1 on which the gate electrode 2 is formed is placed in a region of the reaction chamber C to which the first source material gas is supplied and heated to 300 ° C. (a heater is not shown), and turbo molecules are added. The inside of the reaction chamber C is evacuated to 5 × 10 ⁻⁷ Torr by the pump VP.

Next, the valve is opened to V ₀ and Ar gas is caused to flow from the gas inlet N _c into the reaction chamber C for 500 sccm, and the orifice valve OF is squeezed until the pressure reaches 0.01 Torr to make a steady flow of Ar gas. This becomes the barrier gas.

Next, trimethyl aluminum (TMA
trimethylaluminum vapor generated by heating l) vessel 60 ° C., flowed from a gas inlet N _a Ar gas as a carrier gas by opening the valve V ₁ to the reaction chamber C.

Next, the valve V ₂ is opened, and steam is flowed from the water container kept at 20 ° C. into the reaction chamber C from the gas inlet N _b using Ar gas as a carrier gas. The barrier gas flow of Ar gas separates trimethylaluminum vapor and water vapor and does not mix. At this time, the pressure in the reaction chamber C is 0.01
Keep on Torr.

The glass substrate 1 mounted on the moving mechanism is moved between the trimethylaluminum vapor and the water vapor at a speed that does not disturb the steady flow thus created, for example, a cycle of reciprocating 3 seconds. By repeating this reciprocation 6000 times, a 4000 Å-thick alumina polycrystalline film was formed.
This alumina polycrystal film becomes the gate insulating film 3.

Next, the valve V ₁ is closed to block the trimethylaluminum vapor, and the valve V ₃ is opened to open the monosilane gas (S
iH ₄ ) is flowed into the reaction chamber C at 50 sccm. The valve V ₂ is closed to shut off water vapor, and the valve V ₄ is opened to release hydrogen gas (H ₂ ) to 5
Flowing into the reaction chamber C at 0 sccm, the radio frequency power (RF) is supplied to the plasma cathode PC to generate hydrogen plasma.
The barrier gas Ar is kept flowing.

The glass substrate 1 mounted on the moving mechanism is moved between the monosilane gas and the hydrogen gas at a speed that does not disturb the steady flow, for example, at a cycle of reciprocating 3 seconds. This round trip
By repeating 100 times, the thickness of 400 Å a-Si:
An H film (hydrogenated a-Si film) was formed. This a-
The Si: H film becomes the operating semiconductor film 4.

In the process of forming an a-Si: H film, the monosilane gas is first adsorbed on the glass substrate 1, and in the next step hydrogen plasma reacts with the adsorbed monosilane to form almost a single layer of hydrogenated a-Si. Formed, and this is repeated
It is considered that the i: H film is formed.

See FIG. 1 (c). The plasma CVD method is used to form an S layer having a thickness of, for example, 2000 Å.
After forming the iO ₂ film, a positive resist is applied, and the positive resist is exposed and developed by a backside exposure method using the gate electrode 2 as a mask, and the SiO ₂ film is etched using this as a mask to form the channel protective layer 5. To do.

See FIG. 1 (d). An n ⁺ type a having a thickness of, for example, 2000 Å is formed by the plasma CVD method.
-Si film is deposited, and then Ti film with a thickness of 1500 Å is deposited by the sputtering method.
The film, the n ⁺ type a-Si film, and the a-Si film 4 are etched to form the source 6a and the drain 6 made of the n ⁺ type a-Si film.
b, a source electrode 7a and a drain electrode 7b made of a Ti film are formed.

Referring to FIG. 1 (e), an ITO film having a thickness of 2000 Å, for example, is deposited on the entire surface by a sputtering method, and then it is etched using a mask to form a pixel electrode 8 connected to the source electrode 7a.

Next, an Al film having a thickness of, for example, 3000 Å is deposited on the entire surface by a sputtering method, and then it is etched using a mask to form a drain bus line 9 connected to the drain electrode 7b.

After that, a surface protection film 10 of SiN _x having a thickness of 2000 Å is formed on the entire surface by, for example, the plasma CVD method.
Since the gate insulating film 3 and the operating semiconductor film 4 are both formed by the atomic layer epitaxy method and can be formed without breaking the vacuum in the process, contamination and a decrease in adhesion force occur at the interface between the gate insulating film 3 and the operating semiconductor film 4. Absent.

In this way, the TF having the highly dense gate insulating film and the operating semiconductor film of a-Si having good film quality is obtained.
T could be formed. Next, a second embodiment will be described.

The formation of the gate insulating film 3 is the same as in the first embodiment. Operating semiconductor film 4 after formation of gate insulating film 3
Is formed as follows. The valve V ₁ is closed to block the trimethylaluminum vapor, and the valve V ₃ is opened to allow monosilane gas (SiH ₄ ) to flow into the reaction chamber C at 50 sccm. Water vapor is removed from the valve V ₂ and only Ar gas is allowed to flow into the reaction chamber C, and radio frequency power (RF) is supplied to the plasma cathode PC to generate A
r Plasma is generated. The barrier gas Ar is kept flowing.

The glass substrate 1 mounted on the moving mechanism is moved between the monosilane gas and the Ar plasma at a speed that does not disturb the steady flow, for example, a cycle of 3 seconds of reciprocation. By repeating this reciprocation 100 times, the thickness of 400 Å aS
The i film 4 is formed.

In the process of forming an a-Si film, monosilane gas is first adsorbed on the glass substrate 1, and in the next step Ar plasma decomposes the adsorbed monosilane to form a-Si.
It is considered that this is repeated to form the a-Si film 4.

The following steps are the same as in the first embodiment.
In this way, a TFT having a highly dense gate insulating film and an a-Si operating semiconductor film of good film quality can be formed.

Next, the third embodiment will be described. FIG. 4 is a schematic diagram of another atomic layer epitaxy apparatus, in which the atomic layer epitaxy apparatus shown in FIG. 3 is provided with a region independent of the source material gas supply region, and plasma processing is performed there. Gas inlet N for introducing Ar gas
_d , N _e , N _f , and valves V ₅ , V ₆ , and V ₇ are added, and a mechanism is provided which can rotate the glass substrate 1 along the circumference and reciprocate.

A third embodiment will be described with reference to FIGS. The steps up to the formation of the gate insulating film 3 are the same as those in the first embodiment, but when forming the gate insulating film 3, the valves V ₅ and V ₆ are opened and the Ar gas is supplied as a barrier gas from the gas inlets N _d and N _e. Shed as. Atomic layer epitaxy is carried out by reciprocating the glass substrate 1 between the first source material gas (TMAl) and the second source material gas (H ₂ O) to form the gate insulating film 3.

Next, the operation semiconductor film 4 is formed as follows. The valve V ₁ is closed to shut off trimethylaluminum vapor, and the valve V ₃ is opened to allow monosilane gas (SiH ₄ ) to flow into the reaction chamber C. Close the valve V ₂ to shut off H ₂ O + Ar,
The valve V ₄ is opened to allow H ₂ to flow into the reaction chamber C. Valve V ₇ to A
r gas is supplied, and radio frequency power (RF) is supplied to the plasma cathode PC to generate Ar plasma. The barrier gas Ar is kept flowing.

The glass substrate 1 mounted on the moving mechanism is rotated so as to be successively exposed to monosilane gas, hydrogen gas, and Ar plasma at a speed that does not disturb the steady flow, for example, at a cycle of 1 rotation / second. By continuing this rotation 100 times, the a-Si: H film 4 having a thickness of 400 Å is formed.

In the process of forming an a-Si: H film, monosilane gas is first adsorbed on the glass substrate 1, hydrogen gas is adsorbed in the next step, and Ar plasma adsorbs adsorbed monosilane and hydrogen in the next step. Almost a single layer of a-Si: H by reaction
It is considered that the a-Si: H film 4 is formed by repeating the above process.

The following steps are the same as in the first embodiment.
In this way, a TFT having a highly dense gate insulating film and an a-Si operating semiconductor film of good film quality can be formed.

Next, a fourth embodiment will be described. In this example, the glass substrate 1 is rotated in the opposite direction when the operating semiconductor film of the third embodiment is formed. That is, the glass substrate 1 is rotated so as to be sequentially exposed to monosilane gas, Ar plasma, and hydrogen gas.

In this case, monosilane gas is first adsorbed on the glass substrate 1, and in the next step Ar plasma decomposes the adsorbed monosilane to form a-Si, and in the next step hydrogen reacts with a-Si. Almost monolayer of hydrogenated a-S
It is considered that i is formed and the process is repeated to form the a-Si: H film 4.

The following steps are the same as in the first embodiment.
In this way, a TFT having a highly dense gate insulating film and an a-Si operating semiconductor film of good film quality can be formed.

In the first to fourth embodiments, when the gate insulating film 2 is formed by the atomic layer epitaxy method, TMAl is used as the first source material gas, but instead of this, trimethylamine alane is used. (TMA
A), alkylamine alane such as triethylamine alane (TEAA), or aluminum chloride (AlCl ₃ ) can also be used.

FIGS. 2A to 2E are sectional views in order of steps for explaining another embodiment. The fifth to seventh embodiments will be described below with reference to these figures and FIG.

Fifth Embodiment Referring to FIG. 2 (a), a Ti film having a thickness of 1000 Å is formed by sputtering, for example, on an NA40 glass substrate as a glass substrate 1 and is etched by using a mask to form the gate electrode 2 To form.

Referring to FIG. 2B, an Al ₂ O ₃ film 3a to be a gate insulating film is formed by the atomic layer epitaxy apparatus shown in FIG. 3 (however, trimethylamine alane is used instead of TMAl as the first raw material). .. First, the glass substrate 1 on which the gate electrode 2 is formed is placed in the reaction chamber C, heated to 300 ° C. (a heater is not shown), and the inside of the reaction chamber C is 5 × 1 by the turbo molecular pump VP.
Exhaust to 0 ^-7 Torr.

Next, the valve is opened to V _0, and Ar gas is caused to flow from the gas introduction port N _c into the reaction chamber C for 500 sccm, and the orifice valve V ₀ is squeezed until the pressure reaches 0.01 Torr to make a steady flow of Ar gas. This becomes the barrier gas.

Next, trimethylamine alane (TMA)
Generates trimethylaminealane steam to heat the vessel to 40 ° C., flowed by opening the valve V ₁ from the gas inlet N _a in the reaction chamber C.

Next, steam is mixed with Ar gas from a water container kept at 20 ° C., the valve V ₂ is opened, and the gas is introduced into the reaction chamber C through the gas inlet N _b . The barrier gas flow of Ar gas separates the trimethylamine alane vapor and water vapor and does not mix. At this time, the pressure in the reaction chamber C is maintained at 0.01 Torr.

The glass substrate 1 mounted on the moving mechanism is moved between the trimethylamine alane vapor and the water vapor at a speed that does not disturb the steady flow thus created, for example, a cycle of 3 seconds of reciprocation. By repeating this reciprocation 3000 times, a 4000 Å-thick alumina polycrystalline film was formed.
The alumina polycrystal film (Al ₂ O ₃ film) 3a becomes a part of the gate insulating film.

Next, the glass substrate 1 is transferred to a plasma CVD apparatus, and SiN _{x having a} thickness of 200 Å is formed by plasma CVD.
The film 3b and the a-Si film 4 having a thickness of 400Å are continuously formed. Si
The N _x film 3b becomes a part of the gate insulating film, and the a-Si film 4 becomes an operating semiconductor film.

See FIG. 2 (c). The plasma CVD method is used to form an S film having a thickness of, for example, 2000 Å.
After forming the iO ₂ film, a positive resist is applied, and the positive resist is exposed and developed by a backside exposure method using the gate electrode 2 as a mask, and the SiO ₂ film is etched using this as a mask to form the channel protective layer 5. To do.

See FIG. 2 (d). An n ⁺ type a having a thickness of, for example, 2000 Å is formed by the plasma CVD method.
-Si film is deposited, and then Ti film with a thickness of 1500 Å is deposited by the sputtering method.
The film, the n ⁺ type a-Si film, and the a-Si film 4 are etched to form the source 6a and the drain 6 made of the n ⁺ type a-Si film.
b, a source electrode 7a and a drain electrode 7b made of a Ti film are formed.

See FIG. 2 (e). An ITO film having a thickness of 2000 Å is deposited on the entire surface by a sputtering method, and then it is etched using a mask to form a source electrode.
The pixel electrode 8 connected to 7a is formed.

Then, the entire surface is sputtered to a thickness of 3000.
After the Å Al film is deposited, it is etched using a mask to form the drain bus line 9 connected to the drain electrode 7b.

Thereafter, a surface protection film 10 of SiN _x having a thickness of 2000 Å is formed on the entire surface by, eg, plasma CVD method.
Both the gate insulating film 3b and the operating semiconductor film 4 are plasma CVs.
Since it is formed by the D method and can be formed without breaking the vacuum in the middle of the process, contamination or a decrease in adhesion does not occur at the interface between the gate insulating film 3b and the operating semiconductor film 4.

Further, since the alkylamine alane is used as the first raw material in the formation of the Al ₂ O ₃ film to be the gate insulating film 3a, the insulating material is highly dense and has high purity without carbon contamination. A film is formed.

In this way, a highly dense gate insulating film and an a- film having a good adhesion with the gate insulating film and a good film quality are formed.
A TFT having an operating semiconductor film of Si could be formed. As the first raw material, it is also possible to use alkylamine alane such as triethylamine alane instead of trimethylamine alane.

Sixth Embodiment In this example, the atomic layer epitaxy method is applied to the formation of the channel protective layer 5. The other steps are the same as in the fifth embodiment.

By using the atomic layer epitaxy apparatus shown in FIG. 3, an Al ₂ O ₃ film serving as a channel protective layer is formed to a thickness of 2000 Å, for example, and the channel protective layer 5 is formed by patterning it. Since the Al ₂ O ₃ film may be formed according to the fifth embodiment described above, the description thereof will be omitted.

An Al ₂ O ₃ film is formed as a part of the channel protection layer by an atomic layer epitaxy method, and a SiN _x film which becomes a part of the channel protection layer is formed thereon by, for example, a plasma CVD method. Alternatively, a double film channel protection layer may be formed. The channel protective layer including the Al ₂ O ₃ film formed by the atomic layer epitaxy method is highly dense, has high mechanical strength, and has large insulation resistance and stability.

Seventh Example In this example, an atomic layer epitaxy method is applied to the formation of the surface protective film 10. The other steps are the same as in the fifth embodiment.

An Al ₂ O ₃ film to be the surface protection film 10 is formed with a thickness of Å by the atomic layer epitaxy apparatus shown in FIG. Since the Al ₂ O ₃ film may be formed according to the fifth embodiment described above, the description thereof will be omitted.

An Al ₂ O ₃ film formed by the atomic layer epitaxy method is formed as a part of the surface protection film, and a SiN _x film which becomes a part of the surface protection film is formed on the Al ₂ O ₃ film, for example, by plasma C
It may be formed by the VD method to form a double-layer surface protective film. Al ₂ O by atomic layer epitaxy
_The surface protective film including the _three films is highly dense, has high mechanical strength, and has high insulation resistance and stability.

[0080]

As described above, according to the present invention,
By applying the atomic layer epitaxy method to the formation of the insulating film, the denseness of the insulating film such as the gate insulating film of the TFT, the channel protective layer, the surface protective film, etc. is increased, the mechanical strength is increased, and the insulation withstand voltage and insulation resistance are Can be large.

Further, by forming the gate insulating film and the operating semiconductor film continuously without breaking the vacuum, it is possible to prevent the interface between the gate insulating film and the operating semiconductor film from being contaminated and the adhesiveness from being deteriorated. be able to. Therefore, the quality of the operating semiconductor film becomes good, and a TFT having good transistor characteristics can be formed.

The present invention contributes to the performance improvement and the yield improvement of the TFT matrix.

[Brief description of drawings]

1A to 1E are sectional views in order of processes, for explaining an embodiment.

2A to 2E are cross-sectional views in order of the processes, for explaining another embodiment.

FIG. 3 is a perspective view of an atomic layer epitaxy apparatus.

FIG. 4 is a schematic view of another atomic layer epitaxy apparatus.

FIG. 5 is a sectional view of a TFT.

[Explanation of symbols]

Reference numeral 1 is an insulating substrate and a transparent insulating substrate, a glass substrate 2 is a gate electrode 3, a gate insulating film 3a is a gate insulating film, an Al ₂ O ₃ film 3b is a gate insulating film and a SiN _x film 4 Is an operating semiconductor film, an a-Si film, and a-Si:
H film 5 is channel protection layer 6a Source 6b Drain 7a Source electrode 7b Drain electrode 8 Pixel electrode 9 Drain bus line 10 Surface protection film 11 First source material Gas 12 Second source material gas 13 is reaction chamber PC is Ar gas V ₁ ~V ₇ the valve N _a to N _f is the gas inlet port C a barrier gas plasma cathode RF high frequency power OF orifice valve VP turbomolecular pump

Claims (8)

[Claims] 1. A gate electrode (2), a gate insulating film (3), an operating semiconductor film (4), a channel protective layer (5), and a channel protective layer (5), which are sequentially stacked on an insulating substrate (1). In the fabrication of a thin film transistor having a source electrode (7a) and a drain electrode (7b) arranged on both sides of 5), a gate insulating film (3) is formed by the atomic layer epitaxy method, and then by the atomic layer epitaxy method. Operating semiconductor film
A method of manufacturing a thin film transistor, which comprises forming (4). 2. When the operating semiconductor film (4) is formed, the insulating substrate (1) is exposed to an atmosphere containing a first source material gas to expose the first source material gas to the insulating substrate (1). And a second step of exposing the insulating substrate (1) to a plasma atmosphere containing a second source material gas,
The operating semiconductor film (4) is formed by an atomic layer epitaxy method in which the cycle of the second step of reacting with the first raw material adsorbed on the insulating substrate (1) to form a semiconductor is repeated a plurality of times.
The method of manufacturing a thin film transistor according to claim 1, wherein the thin film transistor is formed. 3. When the operating semiconductor film (4) is formed, the insulating substrate (1) is exposed to an atmosphere containing a first source material gas to expose the first source material gas to the insulating substrate (1). And a second step of exposing the insulating substrate (1) to an atmosphere containing a second source material gas to adsorb the second source material gas to the insulating substrate (1). And the insulating substrate (1)
Is exposed to a plasma atmosphere to react the adsorbed first source material with the adsorbed second source material to form a semiconductor, and the semiconductor is formed by an atomic layer epitaxy method in which a cycle of a third step is repeated a plurality of times. The method for producing a thin film transistor according to claim 1, wherein the film (4) is formed. 4. When the operating semiconductor film (4) is formed, the insulating substrate (1) is exposed to an atmosphere containing a first source material gas to expose the first source material gas to the insulating substrate (1). Including a first raw material gas, a second step of exposing the insulating substrate (1) to a plasma atmosphere to decompose and denature the adsorbed first raw material, and a second raw material gas By exposing the insulating substrate (1) to an atmosphere and reacting the second raw material with the modified first raw material to form a semiconductor, the third step cycle is repeated a plurality of times by an atomic layer epitaxy method. 2. An active semiconductor film (4) is formed.
A method for manufacturing the thin film transistor described. 5. When forming the operating semiconductor film (4), the insulating substrate (1) is exposed to an atmosphere containing a raw material gas to adsorb the raw material gas to the insulating substrate (1). The operating semiconductor film (4) by an atomic layer epitaxy method in which the cycle of the step and the second step of exposing the insulating substrate (1) to a plasma atmosphere to decompose the raw material to form a semiconductor is repeated a plurality of times. The method of manufacturing a thin film transistor according to claim 1, wherein the thin film transistor is formed. 6. A gate electrode (2), a gate insulating film (3), an operating semiconductor film (4), a channel protective layer (5) and a channel protective layer (5), which are sequentially laminated on an insulating substrate (1). In manufacturing a thin film transistor having a source electrode (7a) and a drain electrode (7b) arranged on both sides of 5), an alkylamine alane atmosphere and an oxygen-containing atmosphere are alternately formed when forming the gate insulating film (3). A method for producing a thin film transistor, characterized in that a compound insulator is formed by an atomic layer epitaxy method in which the insulating substrate (1) is exposed a plurality of times, and all or part of the gate insulating film (3) is formed. 7. A gate electrode (2), a gate insulating film (3), an operating semiconductor film (4), a channel protective layer (5) and a channel protective layer (5), which are sequentially laminated on an insulating substrate (1). In manufacturing a thin film transistor having a source electrode (7a) and a drain electrode (7b) arranged on both sides of (5), an alkylamine alan atmosphere and an atmosphere containing oxygen are alternately formed when forming the channel protective layer (5). To the insulating substrate
A method of manufacturing a thin film transistor, which comprises forming a compound insulator by an atomic layer epitaxy method in which (1) is exposed a plurality of times to form all or part of the channel protective layer (5). 8. A gate electrode (2), a gate insulating film (3), an operating semiconductor film (4), a channel protective layer (5) and a channel protective layer (5), which are sequentially stacked on an insulating substrate (1). In the production of a thin film transistor having a source electrode (7a) and a drain electrode (7b) arranged on both sides of (5) and a surface protective film (10), when the surface protective film (10) is formed, an alkylamine alane Forming all or part of the surface protective film (10) by forming a compound insulator by an atomic layer epitaxy method in which the insulating substrate (1) is exposed to an atmosphere and an atmosphere containing oxygen alternately. A method of manufacturing a thin film transistor having the characteristics.