JPH07162002A - Manufacture of semiconductor film and manufacture of thin-film transistor - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a semiconductor film of high quality with good mass productivity and a method of manufacturing a thin film transistor using this semiconductor film with good mass productivity. CONSTITUTION:A method of manufacturing a semiconductor film consists of at least a process for forming a non-single crystal semiconductor film 2 on an insulative substrate 1, a process for oxidizing a surface layer of the film 2 to form an oxide film and a process for manufacturing the semiconductor film 21 by removing the oxide film and a method of manufacturing a thin film transistor is performed using this semiconductor film. Thereby, a large low-cost glass substrate can be used and the method of manufacturing the semiconductor film of high quality, which is high in throughput and is suitable to mass production, and the thin-film transistor can be provided. Moreover, all the characteristics, such as a mobility to show the performance of the transistor, of the transistor can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor film. Further, the present invention relates to a method of manufacturing a thin film transistor used for manufacturing a drive circuit of a liquid crystal display, an image sensor and the like.

[0002]

2. Description of the Related Art In recent years,
In order to build an externally mounted drive circuit for a liquid crystal display, an image sensor, etc. on the same substrate as a display, an image sensor, it is increasingly necessary to fabricate a thin film transistor on a transparent insulating substrate such as a glass substrate. . For example, when a thin film transistor is manufactured over a large-area glass substrate, the transistor needs to be manufactured by a low temperature process at 700 ° C. or lower at which a glass substrate can be used. In addition, the characteristics of thin film transistors are generally greatly affected by the quality of a semiconductor film that serves as a channel.

Here, in order to form a driving circuit, it is necessary to manufacture a transistor having high mobility. In order to manufacture a high mobility thin film transistor by a low temperature process, it is indispensable to reduce defects in the semiconductor film and manufacture a high quality semiconductor film. A polycrystalline silicon film, which is usually used as a semiconductor film, is crystallized by a solid phase growth method in which amorphous silicon is used as a starting material and annealed at about 600 ° C. to form polycrystalline silicon, rather than by direct film formation. It is known that the particle size becomes large and the uniformity is good over a large area (U. Mitra et al, IEEE, Electron
Device Letters, Vol.12, No.7).

However, in the semiconductor film obtained by this solid phase growth method, defects remain in crystal grain boundaries, crystal grain boundaries, etc., so that the transistor characteristics cannot be sufficiently improved. In addition, there is a problem that it is necessary to carry out a process having a large throughput and a large mass productivity at a low temperature of 700 ° C. or less, which can use an inexpensive glass substrate having a large area.

[0005]

Thus, according to the present invention, a step of forming a non-single-crystal semiconductor film on an insulating substrate, and a surface layer of the non-single-crystal semiconductor film is oxidized to form an oxide film. There is provided a method for producing a semiconductor film, comprising the steps of: and a step of producing a semiconductor film by removing the oxide film.

Further, according to the present invention, the step of forming a non-single crystal semiconductor film on an insulating substrate, the step of forming a polycrystalline semiconductor film by annealing the non-single crystal semiconductor film, A step of oxidizing the surface layer of the crystalline semiconductor film to form an oxide film; a step of manufacturing the semiconductor film by removing the oxide film; a step of etching the semiconductor film to form an island shape; There is provided a method of manufacturing a thin film transistor, comprising a step of forming an insulating film and a step of forming a gate electrode. In particular, the method for producing a semiconductor film of the present invention is characterized in that the step of forming an oxide film is performed in an atmosphere containing water vapor, further under high pressure, and particularly at 700 ° C. or lower.

The manufacturing method of the present invention will be described below. First, as the insulating substrate that can be used in the present invention, a known substrate can be used, for example, a glass substrate, quartz,
Examples thereof include sapphire, polymer film, resin and the like. Further, this substrate may be covered with an insulating film. Further, in the present invention, since the semiconductor film can be manufactured at 700 ° C. or lower, it is possible to use an inexpensive and large area high strain point glass substrate.

A non-single crystal semiconductor film is formed on this insulating substrate. As the non-single-crystal semiconductor film, a polycrystalline semiconductor film, a microcrystalline semiconductor film, an amorphous semiconductor film, or the like can be used. Moreover, as the material thereof, silicon, silicon germanium, or the like can be used.

For example, when an amorphous silicon film is used, its manufacturing method is not particularly limited, but plasma C
A VD method, a remote plasma CVD method, a CVD method, a sputtering method or the like can be used, and a reduced pressure or normal pressure CVD method is more preferable. When the film is formed by the low pressure CVD method, the film forming condition varies depending on the film thickness to be formed, but the substrate temperature is 40
0 to 600 ° C. is preferable, pressure is 1.0 to 100 Torr
Can be done at. The raw material gas used is Si
_{H 4, Si 2 H 6,} SiF 4, or the like can be used SiF ₂ Cl _2. Further, the film thickness formed is not particularly limited, but is preferably 50 to 300 nm, and more preferably 50 to 200 nm.

Next, when using a polycrystalline silicon film,
The manufacturing method is, the amorphous semiconductor film, in vacuum or under an inert gas atmosphere such as nitrogen, argon, lamp annealing, laser annealing, electron beam annealing,
It can be obtained by annealing treatment such as furnace annealing. The annealing temperature is 500 to 650 ° C.
The time is preferably 6 to 48 hours. Also, a polycrystalline silicon film may be formed from the beginning.

Next, when a microcrystalline silicon film is used,
The manufacturing method is as follows: SiH ₄ / H by plasma CVD method
The _second gas ratio of 1 / 2-1 / 100 mixed gas is introduced, it can be obtained by forming a substrate temperature 200 to 400 ° C.. Further, when silicon germanium is used, it is manufactured by differently mixing the raw material in which the Si part is replaced with Ge in the above-mentioned method for manufacturing the amorphous, polycrystalline and microcrystalline silicon films. be able to.

Next, the non-single crystal semiconductor film is subjected to an oxidation treatment in an atmosphere of oxygen, water vapor or the like to form an oxide film having a thickness of 5 to 7
The thickness is 00 nm, preferably 10 to 500 nm. If the oxidation temperature is 700 ° C. or lower, an inexpensive glass substrate can be used, and a plurality of substrates can be processed, which is preferable. In addition, the treatment in a steam atmosphere,
It is more preferable because the oxidation rate is improved. Furthermore, 1-5
It is preferable to carry out under a high pressure of 0 atm, particularly 5 to 25 atm, because the oxidation rate is further improved.

Next, the oxide film is removed by etching to form a semiconductor film. The etching method may be either dry etching or wet etching. Examples of dry etching include plasma etching and sputter etching, and examples of wet etching include dipping, running water, and spraying. here,
When the oxide film is SiO ₂ , as a usable etchant, a fluorine-based gas such as CHF ₃ is preferably used in dry etching, while a hydrofluoric acid-based etching solution is preferably used in wet etching.

By forming a semiconductor film through the above steps, a high-quality semiconductor film having a smaller defect density (spin density) than a non-single-crystal semiconductor film before being processed by the steps of the present invention can be obtained. You can Further, in this invention,
A method of manufacturing a thin film transistor using the method of manufacturing a semiconductor film is also provided. The method of manufacturing the thin film transistor will be described below.

First, as described in the method of manufacturing a semiconductor thin film, a polycrystalline semiconductor film is formed on an insulating substrate. The polycrystalline semiconductor film is subjected to an oxidation treatment and an etching removal treatment in the same manner as described above to obtain a high quality polycrystalline semiconductor film. Next, the polycrystalline semiconductor film is formed into an island shape by etching. The etching method is not particularly limited, and either wet etching or dry etching may be used. Then, a gate insulating film is formed with a thickness of 50 to 150 nm on the island-shaped polycrystalline semiconductor film. This gate insulating film is formed by atmospheric pressure or low pressure CVD method, plasma CVD method.
It is preferable to use a SiO ₂ film formed by a sputtering method, a remote plasma CVD method, a sputtering method, or the like. It is particularly preferable to anneal the gate insulating film in an atmosphere of an inert gas such as nitrogen or argon at 500 to 700 ° C. for 0.5 to 12 hours because the characteristics of the gate insulating film are improved.

Next, a gate electrode is formed by laminating a gate insulating film on the polycrystalline semiconductor film to a film thickness of 100 to 500 nm and etching. The forming method is not particularly limited, but a method of forming a conductive material such as AlSi, TiN, Ti, and Cr by a CVD method, a sputtering method, or the like can be used.

Next, impurity element ions are implanted using the gate electrode as a mask to form source / drain regions. Examples of the impurity element ions that can be used include boron and arsenic for p-type, and phosphorus for n-type. The ion implantation energy is p
Type 20 to 40 keV, n type 70 to 120 k
eV, dose amount 1 × 10 ^{15 to} 5 × 10 ¹⁵ ions / cm
It is preferable to inject under the condition of ² . Further, activation annealing such as furnace annealing, laser annealing, or lamp annealing can be performed to activate the region into which the impurity element ions are implanted. Also, Japanese Patent Application No. 4-
As described in Japanese Laid-Open Patent Publication No. 307350, it is more preferable to implant the impurity element ions and the hydrogen ions at the same time because annealing treatment is not required.

Next, an interlayer insulating film 30 is formed on the entire surface of the insulating substrate.
A film is formed at 0 to 500 nm. The interlayer insulating film is SiO ₂ , S
Examples include iN, PSG, BPSG, and organic thin film.
Of these, a SiO ₂ film formed by the atmospheric pressure CVD method,
Tetraethyl orthosilicate (TEOS, Si (OC
₂ H ₅ ) ₄ ) Atmospheric pressure CVD method using gas, plasma CVD
SiO ₂ film formed by the method or plasma CV
It is preferable to use a SiN film formed by the D method. Further, since the SiN film formed by the plasma CVD method has a high hydrogen content, hydrogen diffuses in the annealing process which is the subsequent step and can terminate the tangling bond in the polycrystalline semiconductor film, which is a good characteristic. It is particularly preferable that a transistor having a can be obtained.

Next, a contact hole is opened in the interlayer insulating film on the source / drain regions and a lead electrode is formed to manufacture a thin film transistor. This extraction electrode is made of Al, AlSi,
Au, Cu, Ni, Ag, Cr, Ti, TiN or alloys thereof, silicide, multi-layer structure, etc. can be used.

[0020]

As described above, according to the present invention, after the non-single crystal semiconductor film is formed on the insulating substrate, the non-single crystal semiconductor film is oxidized to form an oxide film, and the oxide film is removed. The defect density of the non-single-crystal semiconductor film before treatment can be reduced and a high-quality non-single-crystal semiconductor film can be formed.

Below, an initial polycrystal silicon film when a polycrystal silicon film is used as the non-single crystal semiconductor film and a polycrystal silicon film produced by the present invention are subjected to an electron spin resonance method.
Table 1 shows the results of the spin density measured by (Electron Spin Resonance: ESR).

[0022]

[Table 1]

As can be seen from Table 1, according to the present invention, the spin density of the semiconductor film is reduced. This indicates that defects in the film are reduced, and it can be seen that the quality of the semiconductor film is improved. Similarly, a similar effect can be obtained with a non-single crystal semiconductor film such as a microcrystalline film or an amorphous film. In particular, since semiconductor films other than single crystals have defects such as crystal grain boundaries, the above-described action can be obtained and the defects can be reduced to improve the quality of the semiconductor film.

This effect is considered as follows. That is, in the process in which the atoms forming the semiconductor film are oxidized to form an oxide film, oxygen atoms intervene in the bonds in the semiconductor film, so that the atoms forming the semiconductor film are separated from the bonds, The semiconductor constituent atoms are excessively generated. By diffusing the generated semiconductor constituent atoms, defects are buried and the defects are reduced. As a result, it is considered that the quality of the semiconductor film may be improved. Note that the oxide film formed by oxidizing the non-single-crystal semiconductor film and the interface between the oxide film and the non-single-crystal semiconductor film are not good in quality and the interface state density is relatively high; therefore, this film can be removed. It is necessary, and if a new oxide film is needed, it must be formed each time.

By performing the step of oxidizing the non-single crystal semiconductor film to form the oxide film in the atmosphere containing water vapor, the oxidation rate can be increased and the throughput can be improved. In addition, the oxidation rate is improved by one digit or more as compared with the case of oxidizing with oxygen gas. Further, the oxidation in an atmosphere containing water vapor is more suitable for mass production because it can process a plurality of substrates than the oxidation using plasma or the like.

In particular, by performing the treatment under a high pressure and in an atmosphere containing water vapor, the oxidation rate can be further increased and the throughput can be improved. Further, as in the case described above, such oxidation makes it possible to process a plurality of substrates, which is suitable for mass production. Further, by treating at 700 ° C. or lower, a relatively low cost high strain point glass can be used for the insulating substrate, and there is an advantage that a large area can be obtained at a low cost as compared with a quartz substrate or a sapphire substrate. is there.

As described above, it is possible to provide a method for producing a high-quality semiconductor film, which has a high throughput and is suitable for mass production, at a temperature of 700 ° C. or lower at which a glass substrate which can be manufactured in a large area at a low cost can be used. Table 2 shows the characteristics of the n-type thin film transistor manufactured by the conventional method and the n-type thin film transistor according to the present invention.

[0028]

[Table 2]

The thin film transistor according to the conventional method 1 of (a) in the above table was manufactured as follows. First, an Si ₂ H ₆ gas was used as an insulating substrate to form an amorphous silicon film at a substrate temperature of 450 ° C. Next, a polycrystalline silicon film was formed by annealing in nitrogen gas at 600 ° C. for 24 hours, and was etched and processed into islands. Next, as a gate insulating film, by a normal pressure CVD method, 4
A 100-nm-thick silicon oxide film was formed at 30 ° C. Subsequently, a gate electrode was formed on the gate insulating film to manufacture an n-type thin film transistor.

The thin film transistor according to the conventional method 2 in the above table (b) was manufactured as follows. First, an Si ₂ H ₆ gas was used as an insulating substrate to form an amorphous silicon film at a substrate temperature of 450 ° C. Next, a polycrystalline silicon film was formed by annealing in nitrogen gas at 600 ° C. for 24 hours, and was etched and processed into islands. Then, it was oxidized under high pressure (25 atm) in an atmosphere containing water vapor at 600 ° C. for about 2 hours to form a silicon oxide film having a film thickness of 50 nm. Further, a silicon oxide film having a film thickness of 50 nm was formed at 430 ° C. by a normal pressure CVD method to form a gate insulating film having a film thickness of 100 nm (note that
The thickness of the gate insulating film was made uniform and they were stacked in order to improve the breakdown voltage, but the interface between the polycrystalline silicon film and the gate insulating film was
It is formed of a silicon oxide film formed by oxidation. ). Subsequently, a gate electrode was formed on the gate insulating film to manufacture an n-type thin film transistor.

The thin film transistor according to the method of the present invention of (c) in the above table was manufactured as follows. First, an Si ₂ H ₆ gas was used as an insulating substrate to form an amorphous silicon film at a substrate temperature of 450 ° C. Next, in nitrogen gas, 60
A polycrystalline silicon film was formed by annealing at 0 ° C. for 24 hours. Then, it was oxidized under high pressure (25 atm) in an atmosphere containing water vapor at 600 ° C. for about 2 hours to form a silicon oxide film having a film thickness of 50 nm. After that, the silicon oxide film was removed by etching. The polycrystalline silicon film of which the quality is improved by this oxidation treatment is etched and processed into an island shape, and a normal pressure C is used as a gate insulating film.
A silicon oxide film having a film thickness of 100 nm was formed at 430 ° C. by the VD method. Subsequently, a gate electrode was formed on the gate insulating film to manufacture an n-type thin film transistor.

As is clear from Table 2 above, the thin film transistor of the present invention has all the characteristics showing the performance of the transistor such as mobility, threshold value and S coefficient. In particular, it can be seen that the mobility is remarkably improved and the performance is improved. As described above, it can be manufactured at a process temperature of 700 ° C. or lower, which enables the use of a low-cost glass substrate,
Further, it is possible to provide a method of manufacturing a thin film transistor having good performance with high mass productivity.

[0033]

Embodiment 1 Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 3 are sectional views showing a method of manufacturing a semiconductor film according to an embodiment of the present invention. As shown in FIG. 1, on a glass substrate 1 which is an insulating substrate, SiH ₄ was used as a source gas by a low pressure CVD method at a substrate temperature of 550 ° C. and a film thickness of 150 n.
A non-single-crystal silicon film 2 which is a non-single-crystal semiconductor film of m was formed. The formed non-single-crystal silicon film was annealed in nitrogen as an inert gas at 600 ° C. for 24 hours to form a polycrystalline silicon film having a film thickness of 150 nm.

Next, as shown in FIG. 2, the non-single-crystal silicon film 2 is subjected to a pressure of 2 in a steam atmosphere in an oxidizing furnace.
Oxidation was performed at 5 atm and 600 ° C. to form a silicon oxide film 3 having a film thickness of 125 nm. The oxidation rate during the steam oxidation was set to about 300Å / h. Next, as shown in FIG. 3, the silicon oxide film 3 is removed to a film thickness of 100 nm.
A silicon semiconductor film 21 of was obtained. The silicon oxide film was removed by a wet etching method using a hydrofluoric acid (HF) -based etching solution.

By producing the semiconductor film as described above, a high-quality semiconductor film having a smaller spin density (defect density) than the non-single-crystal silicon film formed first could be obtained. Although the glass substrate is used as the insulating substrate 1 in the first embodiment, a quartz substrate or a glass substrate covered with an insulating film may be used. Also, 7
Since it can be processed at a temperature of 00 ° C. or lower, a relatively low cost high strain point glass can be used for the insulating substrate, and there is an advantage that a large area can be obtained at a low cost as compared with a quartz substrate or a sapphire substrate. is there.

Low pressure CVD is used for forming the amorphous silicon film.
In addition to the method, a plasma CVD method or the like can be used, and Si ₂ H ₆ or the like can be used as the source gas in addition to SiH ₄ . Further, although the amorphous silicon film is solid-phase grown to form a polycrystalline silicon film, the polycrystalline silicon film may be formed from the beginning. As a material for the non-single crystal semiconductor film, silicon germanium (SiGe) or the like can be used in addition to silicon (Si). Alternatively, a microcrystalline film or an amorphous non-single-crystal semiconductor film may be used.

Furthermore, by performing the step of oxidizing the non-single-crystal semiconductor film to form an oxide film in a normal pressure steam atmosphere, the oxidation rate is increased to about 7Å / h as compared with that in an O ₂ gas atmosphere. Therefore, the throughput can be improved. Further, particularly by performing the treatment under a high pressure and in a steam atmosphere, the oxidation rate can be further increased and the throughput can be improved. Furthermore, such an oxidation can process a plurality of substrates, which is suitable for mass production.
It should be noted that instead of water vapor, it can be performed in an O ₂ gas atmosphere.

Example 2 A method of manufacturing the thin film transistor of the present invention will be described. As shown in FIG. 4, a substrate temperature of 450 ° C. was formed on the glass substrate 12 coated with an insulating film by a low pressure CVD method.
Then, an amorphous silicon film having a film thickness of 100 nm was formed. Next, the polycrystalline silicon film was crystallized by annealing this amorphous silicon film for 24 hours at 600 ° C. in an N ₂ gas atmosphere. The thickness of the polycrystalline silicon film was 100 nm. Here, Si ₂ H ₆ was used as the source gas.

Next, this polycrystalline silicon film was oxidized in an atmosphere of steam at 600 ° C. in a steam furnace to form an oxide film. At this time, the processing time is 6
h, 12h, and 24h, and the oxide film thickness is 11, 2 respectively.
It was produced by changing the wavelength to 2 and 44 nm. Next, the oxide film was removed by wet etching with a buffered hydrofluoric acid (BHF) solution to obtain high-quality polycrystalline silicon films of 96, 91, and 72 nm, respectively.

Next, this high-quality polycrystalline silicon film
Is etched to form an island-shaped polycrystalline silicon film 4,
Subsequently, a gate insulating film 7 was formed on this. Gate insulation
The film 7 is formed by SiH at 430 ° C. by the atmospheric pressure CVD method._FourGas and O₂
SiO formed using gas ₂A membrane was used. Film thickness is 10
It was set to 0 nm. Although the atmospheric pressure CVD method was used here,
Method, low pressure CVD method, plasma CVD method, remote control method
Film thickness 50-150 nm by either plasma CVD method
SiO₂It goes without saying that a film may be used.

Next, in order to improve the film quality of the gate insulating film 7, annealing was performed for 12 hours at 600 ° C. in an N ₂ atmosphere. Then, polycrystalline silicon was formed as the gate electrode 8 by the CVD method to a film thickness of 300 nm. Subsequently, as shown in FIG. 4, etching was performed to form a gate electrode 8. Although polycrystalline silicon formed by the CVD method is used here, it may be formed by the sputtering method.
A conductive material such as N, Ti or Cr may be used.

Next, according to the method disclosed in Japanese Patent Application No. 4-307350, ions 11 of boron (p-type) or phosphorus (n-type) which are impurity element ions and hydrogen ions are simultaneously implanted. As a result, the source portion 5 and the drain portion 6 were formed by self-aligning the impurity element. In this case, annealing for activating the impurity ions is not performed, but only the impurity ions are implanted using a normal ion implantation device, and normal activation annealing (furnace annealing, laser annealing, lamp annealing, etc.) is performed. Is also good.

Then, as shown in FIG. 5, an interlayer insulating film 9 is formed.
Filmed The interlayer insulating film 9 is formed by plasma CVD to 30
As a silicon nitride film with a thickness of 500 nm formed at 0 ° C.
It was The silicon nitride film formed by this plasma CVD method is
Since the elemental content is high, annealing at about 400 ° C in the subsequent process
Hydrogen is diffused by the hydrogen, and dangling in the polycrystalline silicon film 4
Good transistor characteristics by terminating the ring bond
Will be obtained. As the interlayer insulating film 9,
SiO by atmospheric pressure CVD method with good step coverage ₂Membrane
Or atmospheric pressure CVD method using TEOS gas, plasma CV
SiO having a film thickness of 300 to 500 nm formed by the D method
₂Membranes may be used.

Next, after forming the contact hole, the extraction electrode 10 was formed at room temperature by a sputtering method to manufacture a thin film transistor. Here, in Table 3, the polycrystalline silicon film was heated at an atmospheric pressure of 600 ° C. using an oxidation furnace.
In a steam atmosphere for 6 hours, 12 hours, 2
The characteristic of the thin film transistor manufactured by changing the film thickness of the oxide film by setting it to 4 h was shown. In addition, it is processed into an island shape without performing oxidation treatment, and it is processed at 430 ° C. by an atmospheric pressure CVD method.
By forming a silicon oxide film by
Except that the gate insulating film is formed in the same manner as described above, and a thin film transistor (normal treatment) manufactured in the same manner as described above, and processed into an island shape without oxidation treatment, and an atmospheric pressure of 600 ° C. using an oxidation furnace.
Introduce steam at ℃, oxidize for 12 hours, then CV
A gate insulating film, which is a silicon oxide film having a film thickness of 100 nm formed by further oxidizing at 430 ° C. by the D method (here, the gate insulating film is formed to make the film thickness of the gate insulating film uniform and to improve the breakdown voltage). However, the interface between the polycrystalline silicon film and the gate insulating film is formed of an oxide film formed by oxidation.) Of a thin film transistor (conventional method 3) manufactured in the same manner as above. The characteristics are also described.

[0045]

[Table 3]

As is clear from Table 3, in the method of the present invention, the characteristics of the transistor such as the mobility, the threshold value and the S coefficient are improved as compared with the normal processing and the conventional method 3. Further, in Conventional Method 3, the mobility is not significantly improved as in the present invention, and the threshold value and the S coefficient are deteriorated and increased. This is because when the silicon oxide film formed by oxidation is used as it is as the gate insulating film as in the normal process and the conventional method 3, the silicon oxide film itself has a large fixed charge and the polycrystalline silicon film and the silicon oxide film have a large fixed charge. It is considered that the threshold and the S coefficient are high because the interface is defective. Moreover, it is considered that the mobility does not improve due to the influence.

FIG. 6 shows the relationship between the oxidation-removed film thickness of the polycrystalline silicon film and the mobility of the n-type transistor when the polycrystalline silicon film is oxidized and removed. High pressure 6 in the figure
Data is also shown when steam is introduced at 00 ° C. to form an oxide film. At this time, the thickness of the polycrystalline silicon film before the oxidation treatment was set to 150 to 300 nm. It can be seen from FIG. 6 that the treatment time is shortened by increasing the pressure as compared with the normal pressure. Further, it can be seen that by increasing the pressure, the mobility can be increased in the same processing time.

[0048]

As described above, according to the method for manufacturing a semiconductor film of the present invention, after forming a non-single crystal semiconductor film on an insulating substrate, the non-single crystal semiconductor film is oxidized to form an oxide film. By forming and removing the oxide film, the defect density of the non-single-crystal semiconductor film before the oxidation treatment can be reduced and a high-quality non-single-crystal semiconductor film can be formed.

Furthermore, by performing the step of forming the oxide film by oxidizing the non-single crystal semiconductor film in an atmosphere containing water vapor, the oxidation rate can be increased and the throughput can be improved. The oxidation rate is improved by one digit or more as compared with the case of oxidizing with oxygen gas. Further, oxidation in an atmosphere containing water vapor is more suitable for mass production because it can process a plurality of substrates than oxidation using plasma or the like.

In particular, by performing the treatment under a high pressure and in an atmosphere containing water vapor, the oxidation rate can be further increased, the processing time can be shortened, and the throughput can be improved. Further, by increasing the pressure, it is possible to achieve high transfer in the same processing time. Further, similarly to the above, such oxidation makes it possible to process a plurality of substrates, which is suitable for mass production.

Further, by treating at 700 ° C. or lower, a relatively low cost high strain point glass can be used for the insulating substrate, and the cost and the area can be increased as compared with a quartz substrate or a sapphire substrate. There are advantages. As described above, it is possible to provide a method of manufacturing a high-quality semiconductor film, which has a high throughput and is suitable for mass production, at a temperature of 700 ° C. or lower at which a glass substrate that can be manufactured in a large area at a low cost can be used.

Further, according to the method of manufacturing a thin film transistor of the invention, it is possible to improve the characteristics of the mobility, the threshold value, and the S coefficient, which show the transistor performance. In particular, the movement is remarkably improved, and a high-performance thin film transistor can be manufactured with high mass productivity. Furthermore, by performing the step of forming the silicon oxide film by oxidizing the polycrystalline silicon film in an atmosphere containing water vapor, the oxidation rate can be increased and the throughput can be improved. The oxidation rate is improved by one digit or more as compared with the case of oxidizing with oxygen gas. Further, oxidation in an atmosphere containing water vapor is more suitable for mass production because it can process a plurality of substrates than oxidation using plasma or the like.

In particular, by performing the treatment under a high pressure and in an atmosphere containing water vapor, the oxidation rate can be further increased, the processing time can be shortened, and the throughput can be improved. Further, by increasing the pressure, it is possible to achieve high transfer in the same processing time. Further, similarly to the above, such oxidation makes it possible to process a plurality of substrates, which is suitable for mass production.

Further, by treating at 700 ° C. or lower, a relatively low cost high strain point glass can be used for the insulating substrate, and the cost and the area can be increased as compared with a quartz substrate or a sapphire substrate. There are advantages. As described above, it is possible to provide a method for manufacturing a thin film transistor which can be manufactured at a process temperature of 700 ° C. or less and has good performance, which can be used as a low-cost glass substrate, and which has good mass productivity.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a manufacturing process of a semiconductor film of the present invention.

FIG. 2 is a schematic cross-sectional view showing a manufacturing process of a semiconductor film of the present invention.

FIG. 3 is a schematic cross-sectional view showing the manufacturing process of the semiconductor film of the present invention.

FIG. 4 is a schematic cross-sectional view showing the manufacturing process of the thin film transistor of the invention.

FIG. 5 is a schematic cross-sectional view showing the manufacturing process of the thin film transistor of the invention.

FIG. 6 is a graph showing the relationship of the mobility of an n-type thin film transistor with respect to the film thickness obtained by oxidizing and removing a polycrystalline silicon film.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Non-single-crystal semiconductor film 3 Oxide film 4 Polycrystalline silicon film 5 Source part 6 Drain part 7 Gate insulating film 8 Gate electrode 9 Interlayer insulating film 10 Extraction electrode 11 Ions composed of impurity element ions and hydrogen ions 12 Glass Substrate 21 High quality non-single crystal semiconductor film

Claims (7)

[Claims] 1. A step of forming a non-single crystal semiconductor film on an insulating substrate, a step of oxidizing a surface layer of the non-single crystal semiconductor film to form an oxide film, and a semiconductor by removing the oxide film. A method of manufacturing a semiconductor film, comprising the steps of manufacturing a film. 2. The method for producing a semiconductor film according to claim 1, wherein the step of forming the oxide film is performed in an atmosphere containing water vapor. 3. The step of forming an oxide film comprises 1 to 50 at
The method for producing a semiconductor film according to claim 1 or 2, which is performed at m and 300 to 700 ° C. 4. The method for producing a semiconductor film according to claim 1, wherein the non-single-crystal semiconductor film is a microcrystalline film, an amorphous film or a polycrystalline film. 5. A step of forming a non-single crystal semiconductor film on an insulating substrate, a step of forming a polycrystalline semiconductor film by annealing the non-single crystal semiconductor film, and a surface layer of the polycrystalline semiconductor film. A step of oxidizing the silicon to form an oxide film, a step of manufacturing a semiconductor film by removing the oxide film, a step of etching the semiconductor film into an island shape, and a step of forming a gate insulating film And a step of forming a gate electrode. 6. The method of manufacturing a thin film transistor according to claim 5, wherein the step of forming the oxide film is performed in an atmosphere containing water vapor. 7. The step of forming an oxide film comprises 1 to 50 at
The method for manufacturing a thin film transistor according to claim 5 or 6, which is performed at m and 300 to 700 ° C.