JPH09312259A - Semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film transistor capable of constituting a circuit which requires high speed operation (generally, an operation speed of several tens MHz or more). SOLUTION: An nickel element is selectively brought into contact with and held in the specified area 205 of an amorphous silicon film 203. Then, crystal is grown in a direction parallel to the substrate, as shown by an arrow 207, by performing heat treatment. Then, a thermal oxidation film 209 is formed by a heat treatment in an oxidizing atmosphere containing a halogen element. At this time, crystallinity improvement and nickel element gettering are proceeded. A thin film transistor is formed by matching the above crystal depositing direction with a direction which connects source and drain areas. Thus, a TFT(Thin Film Transistor) having high characteristics such as mobility of 200cm<2> /Vs or more and an S value of 100mV/dec or below is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD [0001] The invention disclosed in the present specification is:
The present invention relates to a thin film semiconductor having crystallinity. Further, the present invention relates to a method for manufacturing the thin film semiconductor. The present invention also relates to a semiconductor device using the thin film semiconductor. Further, the present invention relates to a method for manufacturing the semiconductor device.

[0002]

2. Description of the Related Art A technique is known in which a silicon film having crystallinity is formed on a glass substrate or a quartz substrate, and a thin film transistor (hereinafter, referred to as a TFT) is formed using the silicon film.

The thin film transistor is called a high-temperature polysilicon TFT or a low-temperature polysilicon TFT.

The high-temperature polysilicon TFT is a technique that utilizes heat treatment at a relatively high temperature of 800 ° C. or 900 ° C. or higher as a means for producing a crystalline silicon film. This technology can be said to be a derivative technology of an IC manufacturing process using a single crystal silicon wafer.

Of course, a quartz substrate that can withstand the above heating temperature is used as the substrate on which the high-temperature polysilicon TFT is manufactured.

On the other hand, the low-temperature polysilicon TFT uses an inexpensive glass substrate (which is naturally inferior in heat resistance to a quartz substrate) as a substrate.

For the production of the crystalline silicon film constituting the low-temperature polysilicon TFT, heating at 600 ° C. or lower, which the glass substrate can withstand, and laser annealing technology which causes almost no thermal damage to the glass substrate are used.

The high-temperature polysilicon TFT is characterized in that TFTs having uniform characteristics can be integrated on a substrate.

On the other hand, the low-temperature polysilicon TFT has a feature that a glass substrate which is inexpensive and can be easily enlarged is used as a substrate.

In the current technology, there is no significant difference in characteristics between the high temperature polysilicon TFT and the low temperature polysilicon TFT.

That is, in terms of mobility, it is 50 to 100 (cm ² / V
s), S value is 200 to 400 (mV / dec) (V _D = 1V)
Something has been obtained by both parties.

This characteristic is significantly inferior to the characteristic of a MOS transistor using a single crystal silicon wafer. Generally, the S value of a MOS transistor using a single crystal silicon wafer is 60 to 70.
(mV / dec).

Under the present circumstances, a high temperature polysilicon TFT is preferable in terms of uniformity of TFT characteristics and high reproducibility when a large number of TFTs of several hundreds × several hundreds are formed on a substrate. Are better. In addition, the high-temperature polysilicon TFT is advantageous in that various process conditions and manufacturing devices in the conventional IC process can be used.

[0014]

At present, the TFT is
It is used to integrate an active matrix circuit and a peripheral drive circuit of an active matrix type liquid crystal display device on the same substrate. That is, the active matrix circuit and the peripheral drive circuit are formed on the same substrate with TFTs.

In such a structure, the source driver circuit of the peripheral drive circuit is required to operate at a frequency of 10 MHz or more. However, the current high temperature polysilicon TFT
The circuit composed of the low-temperature polysilicon TFT has a margin of operating speed up to about several MHz.

Therefore, at present, the liquid crystal display is configured by dividing the operation (called division driving). However, this method has a problem that a striped pattern appears on the screen due to a slight deviation of the division timing.

As a future technology, a peripheral drive circuit (including a shift register circuit and a buffer circuit)
Besides, it is considered to further integrate an oscillation circuit, a D / A converter, an A / D converter, and a digital circuit for performing various image processes on the same substrate.

However, the oscillation circuit, the D / A converter, the A / D converter, and the digital circuit for performing various kinds of image processing are required to operate at a frequency higher than that of the peripheral drive circuit.

Therefore, it is difficult to construct those circuits by using the high temperature polysilicon TFT and the low temperature polysilicon TFT obtained by the current technology.

An integrated circuit composed of MOS transistors using a single crystal silicon wafer has 10
A device capable of operating at 0 MHz or more has been put into practical use.

An object of the invention disclosed in this specification is to obtain a thin film transistor capable of forming a circuit which requires high-speed operation (generally, operating speed of several tens MHz or more) as described above.

It is another object of the present invention to provide a thin film transistor which has characteristics comparable to those of a MOS type transistor manufactured by using a single crystal silicon wafer. Another object is to provide a manufacturing means thereof. Further, it is an object to provide a semiconductor device having a function required for a thin film transistor having such high characteristics.

[0023]

One of the inventions disclosed in the present specification is a semiconductor device using a thin film transistor having a crystalline silicon film formed on a substrate having an insulating surface as an active layer. The crystalline silicon film has a crystal structure having continuity in a predetermined direction, and has a crystal grain boundary extending in the predetermined direction, in the thin film transistor,
A direction connecting the source region and the drain region and the predetermined direction have a predetermined angle, and a thermal oxide film having a thickness larger than that of the crystalline silicon film is formed on the crystalline silicon film. It is characterized by being formed.

An example of the crystalline silicon film having the above crystalline state is shown in FIGS. 6 and 7. FIG. 7 shows a part of FIG. 6 further enlarged. 6 and 7 are photographs of the surface of a crystalline silicon film having a thickness of 250Å observed by a transmission electron microscope (TEM).

The crystalline silicon film as shown in FIGS. 6 and 7 can be obtained by taking the manufacturing steps as shown in the first embodiment.

6 and 7 show a state in which a continuous crystal structure extends from the lower left to the upper right of the drawings. Further, it is also shown that a large number of crystal grain boundaries are formed substantially parallel to the direction in which the continuity of the crystal structure extends.

That is, a direction perpendicular or approximately perpendicular to the direction in which the continuity of the crystal structure exists (see FIG. 6 or FIG. 7).
In the direction from the lower right to the upper right), there are many clear grain boundaries at intervals, and the crystal structure is discontinuous in that direction. That is, the continuity of the crystal structure is impaired in this direction.

In the direction in which the continuity of the crystal structure extends, the continuity of the lattice structure is substantially maintained, and scattering and traps during carrier movement are extremely small as compared with other directions. Has become.

That is, it can be considered that the direction in which the above-mentioned crystal structures are continuous is in a substantially single crystal state in which carriers are not, or hardly, scattered from the crystal grain boundaries.

In order to obtain the above structure, it is important to make the film thickness of the thermal oxide film forming the gate insulating film larger than the film thickness of the crystalline silicon film forming the active layer.

The step of forming the thermal oxide film which constitutes the gate insulating film is an important requirement for obtaining the above-mentioned crystal structure and a TFT having high characteristics as described later. This is because during formation of the thermal oxide film, interstitial silicon atoms existing in the crystalline silicon film or silicon atoms having an unstable bond state are utilized for forming the thermal oxide film, and as a result, the crystallinity of the crystalline This is because such effects as improvement and reduction of defects in the crystalline silicon film can be obtained.

In particular, with the formation of the thermal oxide film, the above-mentioned unique crystal structure can be obtained in a remarkable state.
(If the thermal oxide film is not formed, the continuity of crystals with many line defects will be impaired.)

The structure of the above invention defines the relationship between the direction in which the crystal structure is continuous and the direction connecting the source region and the drain region of the thin film transistor. For the purpose of high-speed operation, it is preferable that the continuous direction of the crystal structure described above and the direction connecting the source region and the drain region are matched or substantially matched. By doing so, in the operation of the MOS type thin film transistor, it is possible to provide a structure in which carriers are most likely to move.

By setting the angle formed by the above two directions to a predetermined value, the characteristics of the obtained thin film transistor can be controlled. For example, when a large number of thin film transistor groups are formed on the same substrate, the characteristics of the transistor groups can be made different by forming a plurality of groups having different angles formed by the above two angles.

Further, in the case of a thin film transistor in which an active layer having an N-shape, a U-shape, or an M-shape is bent, the following may be performed. That is,
In the case of a thin film transistor in which the line connecting the source region and the drain region is not a straight line but is bent, the following may be done.

In this case, the continuity direction of the crystal structure described above may be set in accordance with the carrier moving direction in the channel region (the carrier moving direction when viewed as a whole).

Also in this case, the highest speed operation can be expected when the angle formed by the carrier moving direction and the crystal structure continuity direction is 0 °. Of course, this angle can be set as needed.

Another structure of the present invention is a semiconductor device using a thin film transistor having a crystalline silicon film formed on a substrate having an insulating surface as an active layer, the crystalline silicon film having a crystal grain boundary. The extending direction has anisotropy, and in the thin film transistor, the direction connecting the source region and the drain region and the extending direction have a predetermined angle, and the thin film is formed on the crystalline silicon film. Is characterized in that a thermal oxide film having a thickness larger than that of the crystalline silicon film is formed.

Another structure of the present invention is a semiconductor device using a thin film transistor having a crystalline silicon film formed on a substrate having an insulating surface as an active layer, wherein the crystalline silicon film has a crystal grain boundary. Having anisotropy in the extending direction, in the thin film transistor, the moving direction of carriers in the channel region and the extending direction have a predetermined angle, and on the crystalline silicon film, A thermal oxide film having a thickness larger than that of the crystalline silicon film is formed.

The crystalline silicon film in the invention disclosed in this specification is obtained by the following steps.

(1) A metal element that promotes crystallization of silicon typified by nickel is introduced into an amorphous silicon film, and heat treatment is performed to crystallize it.

(2) A thermal oxide film is formed by heat treatment in an atmosphere containing a halogen element.

(3) The thermal oxide film of (2) above is removed.

(4) A thermal oxide film functioning as a gate insulating film is formed again.

As the metal element, nickel is extremely preferable in terms of reproducibility and effect. Generally, this metal element includes Fe, Co, Ni, Ru, Rh, Pd, Os, I
One or more kinds selected from r, Pt, Cu, and Au can be used.

When nickel element is used, the concentration of nickel finally remaining in the silicon film is about 1 × 10 ¹⁴ atoms / cm ^{3 to} 5 × 10 ¹⁸ atoms / cm ³ .

[0047] By filling the delivery conditions of the film formation conditions and the metal elements of the thermal oxide film for performing gettering, the upper limit of this concentration can be reduced to about 5 × 10 ¹⁷ atoms pieces / cm ^3. This concentration can be measured using SIMS (secondary ion analysis method).

Generally, the lower limit of the nickel concentration is
It is about 1 × 10 ¹⁶ atoms / cm ³ . This is because it is usually difficult to eliminate the influence of the nickel element adhering to the substrate or the device in consideration of the cost, and the nickel element remains to the above degree.

Of course, it is possible to further reduce the concentration of nickel element remaining in the crystalline silicon film by reviewing the overall manufacturing process, thoroughly cleaning the apparatus, and thoroughly cleaning the apparatus. It is possible.

Therefore, when a general manufacturing process is followed,
The concentration of the remaining nickel element is 1 × 10 ¹⁶ atoms / c
m ³ ５5 × 10 ¹⁷ atoms / cm ³ .

Further, in the process of forming the thermal oxide film, a gradient or a distribution is generated in the concentration distribution of the nickel element in the thickness direction of the obtained crystalline silicon film due to the relationship that the metal element moves into the thermal oxide film. To do.

Generally, it is observed that the concentration of the metal element increases toward the interface where the thermal oxide film is formed.
Also, depending on the conditions, toward the substrate or the underlying film,
That is, it is observed that the concentration of the metal element increases toward the interface on the back surface side. (This difference largely depends on the quality of the amorphous silicon film that is the starting film)

When a halogen element is contained in the atmosphere when the thermal oxide film is formed, the halogen element also has the same concentration distribution as the above metal element. In other words, the concentration distribution becomes higher toward the front surface and / or the rear surface of the crystalline silicon film. (The difference in concentration distribution depends on the quality of the starting film)

The crystalline silicon film in the invention disclosed in this specification preferably has a final film thickness of 100Å to 75.
0 °, more preferably 150 ° to 450 °. With such a film thickness, a peculiar crystal structure in which crystallinity is continuous in one direction as shown in FIGS. 6 and 7 can be obtained in a more remarkable form with good reproducibility.

The final film thickness of the crystalline silicon film must be determined in consideration of the fact that the film thickness is reduced by forming the thermal oxide film.

According to another aspect of the present invention, a step of forming an amorphous silicon film on a substrate having an insulating surface and a metal element that partially promotes crystallization of silicon in the amorphous silicon film are selected. And a step of performing heat treatment to perform crystal growth in a direction parallel to the substrate from a region where the metal element is selectively introduced to another region, and an oxidation containing a halogen element. Forming a first thermal oxide film by heat treatment in an oxidizing atmosphere, removing the first thermal oxide film, and performing a second heating in an oxidizing atmosphere containing a halogen element.
And the step of forming a thermal oxide film, the thickness of the finally obtained silicon film is smaller than the thickness of the second thermal oxide film.

By adopting the above structure, it is possible to obtain a large effect of forming a thermal oxide film in an oxidizing atmosphere containing a halogen element.

According to another aspect of the invention, a step of forming an amorphous silicon film on a substrate having an insulating surface, and a metal element that partially promotes crystallization of silicon on the amorphous silicon film. And a step of performing a heat treatment to perform crystal growth in a direction parallel to the substrate from the region where the metal element is selectively introduced to the other region, and containing a halogen element. A first thermal oxide film by heat treatment at 800 ° C. to 1100 ° C. in an oxidizing atmosphere, a step of removing the first thermal oxide film, and an oxidizing property containing a halogen element. And a step of forming a second thermal oxide film by heat treatment at 800 ° C. to 1100 ° C. in an atmosphere, and the film thickness of the finally obtained silicon film is the same as that of the second thermal oxide film. It is characterized by being thinner than the film thickness.

If the effect of forming the second thermal oxide film in an oxidizing atmosphere containing a halogen element can be further enhanced, the heat treatment temperature is set in the range of 800 ° C. to 11 ° C. as in the above structure.
The temperature is preferably set to 00 ° C. Note that if this temperature is low, the effect will be greatly reduced.

According to another aspect of the invention, a step of forming an amorphous silicon film on a substrate having an insulating surface, and a metal element that partially promotes crystallization of silicon in the amorphous silicon film are selected. And a step of performing heat treatment to perform crystal growth in a direction parallel to the substrate from a region where the metal element is selectively introduced to another region, and an oxidation containing a halogen element. Forming a first thermal oxide film by heat treatment in an oxidizing atmosphere, removing the first thermal oxide film, and performing a second heating in an oxidizing atmosphere containing a halogen element.
And a step of forming a thermal oxide film, the thickness of the finally obtained silicon film is smaller than the total thickness of the first thermal oxide film and the second thermal oxide film. Characterize.

As described above, by making the total thickness of the two thermal oxide films thicker than the thickness of the crystalline silicon film finally obtained, the action of forming the thermal oxide film becomes remarkable. Obtainable.

Specifically, a crystalline silicon film having a unique crystal structure as shown in FIGS. 6 and 7 can be obtained,
By forming an active layer using the crystalline silicon film, S
When the value is 100 mV / dec or less, the mobility is 200 (cm ² / V
s) It is possible to obtain a TFT having particularly excellent characteristics as described above.

According to another aspect of the invention, a step of forming an amorphous silicon film on a substrate having an insulating surface, and a metal element that partially promotes crystallization of silicon in the amorphous silicon film are selected. And a step of performing heat treatment to perform crystal growth in a direction parallel to the substrate from a region where the metal element is selectively introduced to another region, and an oxidation containing a halogen element. Forming a first thermal oxide film by heat treatment at 800 ° C. to 1100 ° C. in a neutral atmosphere;
Of removing the thermal oxide film, and forming the second thermal oxide film by heat treatment at 800 ° C. to 1100 ° C. in an oxidizing atmosphere containing a halogen element. The film thickness of the obtained silicon film is smaller than the total film thickness of the first thermal oxide film and the second thermal oxide film.

In order to maximize the effect of forming the thermal oxide film, the heating temperature is 800 ° C.
It is very important to have a high temperature such as 1100 ° C.

By adopting the above steps,
The crystalline silicon film disclosed in this specification can be obtained, and further, a MOS type thin film transistor utilizing the uniqueness of its crystal structure can be obtained.

As a method of introducing the metal element, a method of applying a solution containing the metal element, a method of the CVD method,
Examples thereof include a method by a sputtering method and a vapor deposition method, a method by a plasma treatment using an electrode containing the metal, and a method by a gas adsorption method.

As a method of introducing a halogen element, H
Means for containing Cl, HF, HBr, Cl ₂ , F ₂ , Br ₂ , CF _4, or the like in an oxidizing atmosphere (eg, an oxygen atmosphere) can be used.

It is also effective to utilize the action of wet oxidation by introducing hydrogen gas or moisture (water vapor) into the atmosphere during formation of the thermal oxide film. This is effective in forming a thermal oxide film having high smoothness in a shorter time.

The temperature for forming the thermal oxide film is extremely important. Several tens of MHz for the element alone as described later
The above operation can be performed, and the S value is 100 (mV /
dec) In order to obtain a TFT as described below, it is necessary to set the heating temperature during the formation of the thermal oxide film to preferably 800 ° C. or higher, more preferably 900 ° C. or higher.

The upper limit of the heating temperature is appropriately about 1100 ° C. which is the upper limit of the heat resistant temperature of the quartz substrate.

[0071]

BEST MODE FOR CARRYING OUT THE INVENTION In a technique for crystallizing an amorphous silicon film by heating to obtain a crystalline silicon film, a nickel element is held in contact with a partial region of the surface of the amorphous silicon film. By performing the heat treatment, crystal growth is performed in the direction parallel to the substrate from the partial region to the other region.

Then, a first thermal oxide film is formed on the surface of the crystal-grown silicon film. This thermal oxide film is 800 ° C. to 110 ° C. in an oxidizing atmosphere containing a halogen element.
It is formed by performing a heat treatment at 0 ° C.

Then, this thermal oxide film is removed. The crystalline silicon film thus obtained has a structure in which crystal grain boundaries extend in a specific direction as shown in FIGS. 6 and 7 and the crystal structure is continuous in that direction.

The operation of forming this thermal oxide film will be described as follows. That is, according to the formation of the thermal oxide film, interstitial silicon atoms existing in the silicon film and silicon atoms having an unstable bond state are utilized for forming the thermal oxide film. As a result, the crystal structure of the obtained crystalline silicon film becomes clearer, and the defects existing in the film are greatly reduced.

The first thermal oxide film also has a role of removing (gettering) the metal element contributing to crystallization from the silicon film. That is, there is also an effect that the metal element that has moved from the silicon film into the thermal oxide film during the formation of the thermal oxide film is removed to the outside by removing the thermal oxide film.

In the invention disclosed in this specification, the first
A second thermal oxide film is formed after removing the thermal oxide film.

This second thermal oxide film is (1) directly formed on the surface of the exposed crystalline silicon film. (2) It is formed after forming a silicon oxide film (generally a silicified insulating film can be used) by the CVD method. It is formed according to two timings.

Second, the formation of the thermal oxide film is also preferably performed in an oxygen atmosphere containing a halogen element.

The action of the second thermal oxide film is basically the same as the action of the first thermal oxide film. However, the effect on the crystal structure is more important than the effect of gettering of the metal element.

[0080]

【Example】

[Embodiment 1] In this embodiment, by selectively introducing a metal element that promotes crystallization of silicon into an amorphous silicon film, crystal growth in a direction parallel to the substrate, which is called lateral growth, is performed. Concerning how to do.

FIG. 1 shows the manufacturing process of this embodiment. First,
On a quartz substrate 201, a silicon oxide film is
A film is formed to a thickness of 000 mm. Note that the base film 202 is not particularly required if the surface of the quartz substrate has good smoothness and sufficient cleaning is performed.

It should be noted that the use of a quartz substrate as the substrate is the preferable choice under the present circumstances, but the substrate is not limited to quartz as long as it can withstand the heat treatment temperature.

Next, an amorphous silicon film 203 serving as a starting film of a crystalline silicon film is formed to a thickness of 500 ° by a low pressure thermal CVD method.

Next, a silicon oxide film (not shown) is formed to a thickness of 1500 ° and is patterned to
A mask indicated by 04 is formed. This mask is 205
An opening is formed in a region indicated by. This opening 20
5 is formed in the region where the amorphous silicon film 20 is formed.
3 is exposed.

The opening 205 has an elongated rectangular shape having a longitudinal direction in the depth direction and the front direction in the drawing. It is appropriate that the width of the opening 203 is 20 μm or more. The length in the longitudinal direction may be formed to a required length.

Then, a nickel acetate solution containing 10 ppm by weight of nickel element is applied. Then, spin drying is performed using a spinner (not shown) to remove an excess solution. The introduction amount of the nickel element can be controlled by the content concentration of the nickel element in the solution.

In this way, the state where the nickel element exists in the state shown by the dotted line 206 in FIG. 1A is obtained. In this state, a state in which the nickel element is selectively held in contact with a part of the amorphous silicon film at the bottom of the opening 205 is obtained.

Next, in a nitrogen atmosphere containing 3% of hydrogen and containing oxygen as little as possible (also in a nitrogen atmosphere), 600
Heat treatment at 8 ° C. for 8 hours. Then, 2 in FIG. 1 (B)
Crystal growth proceeds in a direction parallel to the substrate 201 as indicated by 07. FIG. 9 shows a schematic diagram of the state of this crystal growth seen from the upper surface.

This crystal growth proceeds from the region of the opening 205 into which the nickel element has been introduced to the periphery. The crystal growth in the direction parallel to the substrate is called lateral growth or lateral growth.

The surface of the laterally grown crystalline silicon film obtained by this crystal growth has very good smoothness as compared with the conventional low temperature polysilicon or high temperature polysilicon. This is considered to be due to the fact that the directions in which the crystal grain boundaries extend are substantially uniform.

The surface of a silicon film, which is generally called polycrystalline silicon or polysilicon, has unevenness of ± 100 Å or more. However, when lateral growth is performed as shown in this example, it has been observed that the surface irregularities are ± 30 ° or less. The unevenness deteriorates the interface characteristics with the gate insulating film and is preferably as small as possible.

Under the heat treatment conditions for the above crystallization, this lateral growth can be performed over 100 μm or more. The silicon film 2 having the region laterally grown in this manner.
I get 08.

The heat treatment for crystal growth is 450
C. to 1100 C. (the upper limit is regulated by the heat resistance of the substrate). In order to secure a certain lateral growth distance, the temperature of the heat treatment is preferably set to 600 ° C. or higher. However, improvements in crystal growth distance and crystallinity by increasing the temperature above that level are not so large. (Accordingly, in consideration of economy and simplification of the process, 600 ° C.
Heat treatment at about 650 ° C is sufficient.)

Then, the mask 204 made of a silicon oxide film for selectively introducing the nickel element is removed.

In this state, the nickel element is unevenly distributed in the film. In particular, the nickel element is present at a relatively high concentration in the region where the opening 205 has been formed and in the tip portion of the crystal growth indicated by 207.

Therefore, in forming the active layer, it is important to avoid those regions. That is, it is important that the region where the nickel element is unevenly distributed does not exist in the active layer.

Irradiation with laser light may be further performed after crystallization. That is, crystallization may be further promoted by irradiation with a laser beam. This laser beam irradiation disperses the mass of nickel element present in the film,
This has the effect of making it easier to remove the nickel element later.
Note that, even if laser light irradiation is performed at this stage, lateral growth does not further progress.

As the laser light, an excimer laser having a wavelength in the ultraviolet region can be used. For example, a KrF excimer laser (wavelength 248 nm) or Xe
A Cl excimer laser (wavelength 308 nm) can be used.

Next, a heat treatment is performed at 950 ° C. in an oxygen atmosphere containing 3% by volume of HCl to obtain a thermal oxide film 209.
Is formed to a thickness of 200 °. With the formation of this thermal oxide film, the film thickness of the silicon film 208 decreases by about 100Å. That is, the thickness of the silicon film is about 400 °.
(Fig. 1 (C))

In general, the thermal oxide film formed on the surface of the silicon film has substantially the same swelling thickness on the surface and the distance of the oxidation that proceeds inside. Thus, for example, 100 °
When a 100.degree. Thermal oxide film is formed on the surface of the silicon film, the thickness of the silicon film is reduced by 50.degree., Resulting in a structure of a 50.degree. Thick silicon film and a 100.degree. Thick thermal oxide film formed on the surface.

In the above steps, as the thermal oxide film is formed, the silicon element having an unstable bonded state in the film is used for forming the thermal oxide film. Then, defects in the film are reduced, and higher crystallinity can be obtained.

At the same time, nickel element is gettered from the film by the formation of the thermal oxide film and the action of chlorine.

Naturally, the nickel element is incorporated into the thermal oxide film in a relatively high concentration. Then, the nickel element in the silicon film 208 is relatively reduced. Thus, the state shown in FIG. 1C is obtained.

After forming the thermal oxide film 209, the thermal oxide film 209 is removed. Thus, a crystalline silicon film 208 with a reduced nickel element concentration is obtained.

The crystalline silicon film thus obtained has a structure in which the crystal structure extends in one direction (this direction coincides with the crystal growth direction) as shown in FIG. 6 or 7.
That is, it has a structure in which a plurality of elongated columnar crystals are arranged in parallel through a plurality of crystal grain boundaries extending in one direction.

Then, patterning is performed to form a pattern 210 composed of a lateral growth region. This island-shaped region 210 will later become the active layer of the TFT.

Here, the pattern is positioned so that the direction connecting the source region and the drain region and the crystal growth direction coincide or substantially coincide with each other. By doing so, the direction in which carriers move and the direction in which the crystal lattice extends continuously can be matched, and as a result, TFTs with high characteristics can be obtained.
Can be obtained.

After forming the pattern 210, a thermal oxide film 211 is formed to a thickness of 300 Å. This thermal oxide film, in an oxygen atmosphere containing HCl 3%,
Obtained by performing heat treatment at 950 ° C.

By forming the thermal oxide film 211, the thickness of the pattern (pattern to be the active layer) 210 becomes 25.
0 °.

Also in this step, the same effect as in the case of forming the thermal oxide film 209 can be obtained. The thermal oxide film 209 becomes a part of the gate insulating film of the TFT.

In this embodiment, the thickness (250 Å) of the active layer 210, which is the finally obtained crystalline silicon film, is
It becomes thinner than the film thickness (300 Å) of the second thermal oxide film 211. By doing so, as shown in FIG. 6 and FIG.
The effect can be obtained in order to obtain a unique crystal structure as shown in.

After that, a silicon oxide film 304 forming a gate insulating film together with the thermal oxide film is formed to a thickness of 1000 Å by the plasma CVD method. (Fig. 2 (A))

Next, an aluminum film for forming a gate electrode is formed to a thickness of 4000Å by the sputtering method. 0.2% by weight of scandium is contained in this aluminum film.

The reason why scandium is contained in the aluminum film is to suppress the generation of hillocks and whiskers in the subsequent steps. Hillocks and whiskers are needle-like or barbed protrusions caused by abnormal growth of aluminum during heating.

After forming the aluminum film, a dense anodic oxide film (not shown) is formed. This anodic oxide film is 3%
An ethylene glycol solution containing tartaric acid is used as an electrolytic solution, an aluminum film is used as an anode, and platinum is used as a cathode. In this step, an anodic oxide film having a dense film quality is formed to a thickness of 100 ° on the aluminum film.

The anodic oxide film (not shown) has a role of improving the adhesion with a resist mask formed later.

The thickness of this anodic oxide film can be controlled by the voltage applied during anodic oxidation.

Next, a resist mask 306 is formed. Then, using this resist mask, the aluminum film is patterned into a pattern indicated by 305. Thus, the state shown in FIG. 2B is obtained.

Here, anodic oxidation is performed again. here,
A 3% oxalic acid aqueous solution is used as the electrolytic solution. By performing anodization in this electrolytic solution using the aluminum pattern 305 as an anode, a porous anodic oxide film 308 is formed.

In this step, the anodic oxide film 308 is selectively formed on the side surface of the aluminum pattern due to the existence of the resist mask 306 having high adhesiveness on the upper portion.

This anodic oxide film can be grown to a thickness of several μm. Here, the film thickness is 600
0 °. The growth distance can be controlled by the anodic oxidation time.

Then, the resist mask 306 is removed.
Next, a dense anodic oxide film is formed again. That is, anodic oxidation is again performed using the above-described ethylene glycol solution containing 3% tartaric acid as an electrolytic solution.

In this step, an anodic oxide film having a dense film quality is formed as indicated by 309 because the electrolytic solution enters the porous anodic oxide film 308.

The film thickness of the dense anodic oxide film 309 is 10
00 °. This film thickness is controlled by the applied voltage.

Here, the exposed silicon oxide film 304 is etched. At the same time, the thermal oxide film 300 is etched. This etching uses dry etching. Then, the porous anodic oxide film 308 is removed using a mixed acid obtained by mixing acetic acid, nitric acid, and phosphoric acid. Thus, FIG.
The state shown in (D) is obtained.

After obtaining the state shown in FIG. 2D, impurity ions are implanted. Here, P (phosphorus) ions are implanted by a plasma doping method in order to manufacture an N-channel thin film transistor.

In this step, regions 311 and 315 that are heavily doped and 312 that are lightly doped are used.
And 314 are formed. This is because the remaining silicon oxide film 310 functions as a semi-transparent mask, and some of the implanted ions are shielded there.

Then, irradiation with laser light (or intense light using a lamp) is performed to activate the region into which the impurity ions are implanted. Thus, the source region 31
1. A channel formation region 313, a drain region 315, and low concentration impurity regions 312 and 314 are formed in a self-aligned manner.

Here, LDD is indicated by 314.
This is a region called a (lightly doped drain) region.
(Fig. 2 (D))

The thickness of the dense anodic oxide film 309 is set to 2
When the thickness is made thicker than 000Å or more, the offset gate region can be formed outside the channel formation region 313 with the thickness.

Although the off-gate region is formed also in this embodiment, it is not shown in the drawing because its size is small, its contribution is small, and the drawing is complicated.

It is to be noted that the anodic oxide film having a dense film quality is
To make it as thick as 2,000 mm or more, 200
Since an applied voltage of V or more is required, attention must be paid to reproducibility and safety.

Next, as the interlayer insulating film 316, a silicon oxide film,
Alternatively, a silicon nitride film or a stacked film thereof is formed. As the interlayer insulating film, a layer made of a resin material over a silicon oxide film or a silicon nitride film may be used.

Then, contact holes are formed, and a source electrode 317 and a drain electrode 318 are formed. Thus, the thin film transistor shown in FIG. 3E is completed.

The TFT shown in this embodiment can have extremely high characteristics which have not been obtained conventionally.

For example, NTFT (N-channel type TF
T), the mobility is 200 to 300 (cm ² / Vs), and the S value is 75
A high performance device of up to 90 (mV / dec) (V _D = 1 V) can be obtained. 120 to 1 for PTFT (P-channel type TFT)
80 (cm ² / Vs), S value is 75 to 100 (mV / dec) (V _D = 1
It is possible to obtain a high-performance product called V).

Particularly, the S value is the same as that of the conventional high temperature polysilicon TF.
及 び compared to the values of T and low temperature polysilicon TFT.
The following are surprisingly good values.

[Embodiment 2] This embodiment relates to an example in which a method for forming a gate insulating film is devised in the structure shown in Embodiment 1.

FIG. 3 shows the manufacturing process of this embodiment. First, a crystalline silicon film 208 having a lateral growth region is obtained according to the steps shown in FIGS. In this case, the starting amorphous silicon film has a thickness of 500 Å.

After the crystalline silicon film is obtained, heat treatment is performed at 950 ° C. in an oxygen atmosphere containing 3% HCl to form a thermal oxide film 209 to a thickness of 200Å. (Fig. 3 (A))

Next, the thermal oxide film 209 is removed. And
By patterning, a pattern 210 to be an active layer of a thin film transistor later is formed. (Fig. 3
(B))

Next, the gate insulating film 304 is formed to a thickness of 1000 Å by the plasma CVD method. (Fig. 3
(C))

Next, heat treatment is performed at 950 ° C. in an oxygen atmosphere containing 3% of HCl to form a thermal oxide film 211 with a thickness of 300 Å. (FIG. 3 (D))

At this time, the thermal oxide film is the CVD oxide film 304.
3D, and is formed into a film as shown in FIG.

When the manufacturing process shown in this embodiment is adopted,
The gate insulating film is composed of a laminated film of the thermal oxide film 211 and the CVD oxide film 304.

When the manufacturing process shown in this embodiment is adopted,
The interface state density at the interface between the gate insulating film and the active layer can be made low.

[Embodiment 3] This embodiment shows a manufacturing process of an active matrix circuit portion of an active matrix type liquid crystal display device.

FIG. 4 shows an outline of the manufacturing process of this embodiment.
First, according to the steps shown in FIGS. 1 and 2, the state shown in FIG. 2D is obtained. (State shown in FIG. 4 (A))

Next, as a first interlayer insulating film, a silicon nitride film 401 is formed to a thickness of 2000 Å by the plasma CVD method. Further, a polyimide resin film 402 is formed by spin coating. Thus, the state shown in FIG. 4B is obtained.
As the resin material, polyamide or polyimide amide can be used in addition to polyimide.

Next, the source region 311 and the drain region 31
A contact hole reaching 5 is formed, and a source electrode 403 and a drain electrode 403 are formed. These electrodes are formed by a laminated film of a titanium film, an aluminum film and a titanium film. The source electrode 403 is formed as extending from the source line. (FIG. 4 (C))

A part of the drain electrode 403 is used as an electrode for forming a storage capacitor.

After forming the source and drain electrodes, a polyimide resin film 404 is formed as a second interlayer insulating film. Thus, the state shown in FIG. 4C is obtained.

Next, an opening is formed in the resin interlayer insulating film 404, and a black matrix (BM) 405 made of a laminated film of a titanium film and an aluminum film is further formed.
The black matrix 405 functions as an electrode for forming an auxiliary capacitance in addition to the original function as a light shielding film.

After forming the black matrix 405,
A polyimide resin film 406 is formed as a third interlayer insulating film. Then, a contact hole to the drain electrode 403 is formed, and a pixel electrode 407 made of ITO is formed.

In this way, a structure is obtained in which the polyimide resin film 406 is sandwiched between the pattern of the black matrix 405 and the pattern of the pixel electrode 407 which function as the auxiliary capacitance.

[Embodiment 4] This embodiment is an example in which, in the structure shown in Embodiment 1, a method of forming a contact with a gate electrode or a gate wiring extending from the gate electrode is devised.

Example 1 (see FIG. 2) or Example 3
In the structure shown in (or Example 3), the side surface and the upper surface of the gate electrode are covered with the anodic oxide film having a dense film quality.

Such a structure has a great effect in terms of suppressing hillocks and suppressing short circuits between wirings when an electrode made of aluminum is formed.

However, there is a problem that it is relatively difficult to form a contact because of its strong film quality.

This embodiment relates to a configuration that solves this problem. FIG. 5 shows a manufacturing process of this example. Detailed manufacturing conditions and the like of the same reference numerals as those of the other examples are the same as those of the other examples.

First, as shown in FIG. 5A, an active layer pattern 210 made of a crystalline silicon film is obtained. Then, a state where the thermal oxide film 211 and the CVD oxide film 304 are laminated is obtained.

Here, a step of first forming a CVD oxide film and then forming a thermal oxide film is adopted.

When the state shown in FIG. 5A is obtained, an aluminum film is formed, and a silicon nitride film is further formed to a thickness of 500Å. Then, patterning is performed using the resist mask 306 to obtain a state in which the aluminum pattern 305 and the silicon nitride film 501 thereon are formed. (FIG. 5 (B))

When the state shown in FIG. 5B is obtained, the porous anodic oxide film 3 is formed with the resist mask 306 arranged.
No. 08, and an anodic oxide film 3 having a denser film quality
09 is formed.

These anodic oxide films are selectively formed only on the side surface of the aluminum pattern 307 to be the gate electrode. This is because the silicon nitride film 501 exists on the upper surface of the aluminum pattern.

After the formation of the anodic oxide film is completed, the resist mask 306 is removed. Then, the exposed silicon oxide film 304 is removed, and a part of the thermal oxide film 211 is also removed.

Thus, the state shown in FIG. 5C is obtained. After obtaining the state shown in FIG. 5C, the resist mask 306 is removed, and further the porous anodic oxide film 308 is removed.

Then, the silicon nitride film 501 is further removed. Thus, the state shown in FIG. 5D is obtained. In this state, the doping of the impurity imparting the conductivity type is performed by the plasma doping method.

As a result, the source region 311, the low concentration impurity regions 312 and 314, the channel region 313, and the drain region 315 are formed in a self-aligned manner.

After the doping of impurities is completed, laser light irradiation is performed to anneal the damage caused at the time of doping and to activate the doped impurities.

Thus, the state shown in FIG. 5D is obtained. Next, the interlayer insulating film 502 is formed. Then, a contact hole is formed, a source electrode 317, a gate extraction electrode 503, and a drain electrode 318 are formed to obtain the state shown in FIG.

In this step, the contact hole can be formed in the gate electrode 307 relatively easily because the anodic oxide film does not exist on the upper surface of the gate electrode.

Although the drawing shows that the source / drain electrode and the gate electrode are formed on the same cross section, the gate extraction electrode is actually formed on the portion extending from the gate electrode 307. It is formed.

[Embodiment 5] This embodiment is an example in which a glass substrate is used as the substrate in the structure shown in the first embodiment.

In this example, the strain point of the substrate was 667 ° C.
Corning 1737 glass substrate of Then, heat treatment for crystallization is performed at 600 ° C. for 4 hours.

The heat treatment for forming the thermal oxide film is HCl.
Is performed under the condition of 640 ° C. in an oxygen atmosphere containing 3% by volume. In this case, the film thickness of the thermal oxide film formed is about 30 Å in 2 hours of processing time. In this case, the effect is small as compared with the case where the heat treatment at 950 ° C. as shown in Example 1 is added.

[Embodiment 6] In this embodiment, in the structure shown in Embodiment 1, H 2 is added in the atmosphere during the formation of the thermal oxide film.
This is an example of the case where Cl is not contained. In this case, HCl
The gettering effect of nickel becomes small as compared with the case of containing in the atmosphere.

[Embodiment 7] This embodiment is an example in the case of irradiating a laser beam after forming a thermal oxide film in the structure shown in Embodiment 1. With this, crystallization can be further promoted. [Embodiment 8] This embodiment shows an example of a semiconductor device using a TFT. FIG. 8 shows examples of various semiconductor devices.

FIG. 8A shows a so-called personal digital assistant, which displays information required for the active matrix type liquid crystal display device 2005 provided in the main body 2001 by calling it from an internal storage device. Or you can display the information accessed using the telephone line.

As a form of the display device, it may be considered to use an active matrix type EL display device.
Various information processing circuits and storage circuits are integrated by using TFTs as an integrated circuit 2006 on the same substrate as the active matrix circuit forming the display device.

The main body 2001 also includes a camera section 200.
2 is provided, and necessary image information can be taken in by operating the operation switch 2004. The image captured by the camera unit 2002 is the image receiving unit 2
It is taken into the device from 003.

FIG. 8B shows a display device called a head mounted display. In this device, a main body 2101 is mounted on the head, and two active matrix type liquid crystal displays 2102 are used to detect the number c in front of the eyes.
It has a function of displaying an image at a position of m. With this device, you can see images in a pseudo-experienced manner.

FIG. 8C shows a car navigation system. This device has a function of measuring a position by using a signal from an artificial satellite received by an antenna 2204. Then, the measured position is displayed on the active matrix type liquid crystal display device 2202. The selection of information to be displayed is performed by the operation switch 2203.

Note that an active matrix EL display device can be used instead of the liquid crystal display device.

FIG. 8D shows an example of a mobile phone. In this device, an antenna 2306 is provided in a main body 2301, and a voice input unit 2303 and a voice input unit 2302 are provided.

When making a call, the operation switch 230
5 is operated. A display device 2304
Various image information is displayed on the screen. As a portable display device, an active matrix type liquid crystal display device or an active matrix type EL display device is used.

FIG. 8E shows a portable video camera. This device has a function of storing an image captured from the image receiving unit 2406 in a magnetic tape stored in the main body 2401.

Various digital processes are applied to the image in the integrated circuit 2407. This integrated circuit 2407
May be composed of a combination of IC chips that have been conventionally used, or a T chip as disclosed in this specification.
You may comprise using FT. Moreover, you may comprise by those combinations.

The image received by the image receiving unit 2406 and the image stored on the internal magnetic tape are displayed on the active matrix type liquid crystal display device 2402. The operation of the device
It is performed by the operation switch 2404. The power of the device is covered by the battery 2405.

FIG. 8F shows a projection type display device. This device has a function of displaying an image projected from the main body 2501 on a screen.

The main body 2501 is provided with a light source 2502, an active matrix type liquid crystal display device 2503 for optically modulating light from this light source to form an image, and an optical system 2504 for projecting an image.

The type of liquid crystal display device is as follows.
Either the transmissive type or the reflective type can be used except for the device shown in FIG.

[0193]

When a PTFT and an NTFT obtained by utilizing the invention disclosed in this specification are combined to form a 9-stage ring oscillator, it is possible to oscillate at 400 MHz or more.

Considering that an actual circuit is generally designed with about 10% of the oscillation frequency of the ring oscillator, it is possible to construct a circuit which operates with a frequency of about 40 MHz with the above TFT.

As described above, by utilizing the invention disclosed in this specification, it is possible to obtain a thin film transistor capable of forming a circuit that requires high-speed operation (generally, operating speed of several tens MHz or more).

Regarding the S value in particular, the MO produced by using a single crystal silicon wafer of 100 (mV / dec) or less.
It is possible to obtain characteristics comparable to those of S-type transistors.

By utilizing the invention disclosed in this specification, circuits which require various high-speed operations can be formed on a single substrate.
It is possible to provide an integrated structure with FT.
In addition, a manufacturing method thereof can be provided.

[Brief description of drawings]

FIG. 1 illustrates a manufacturing process of a thin film transistor.

FIG. 2 illustrates a manufacturing process of a thin film transistor.

FIG. 3 illustrates a manufacturing process of a thin film transistor.

FIG. 4 illustrates a manufacturing process of a thin film transistor.

5A to 5C are diagrams illustrating a manufacturing process of a thin film transistor.

FIG. 6 is an electron micrograph showing a silicon thin film.

FIG. 7 is an electron micrograph showing a silicon thin film.

FIG. 8 is a diagram showing an outline of various semiconductor devices using TFTs.

FIG. 9 is a schematic view showing a state of crystal growth.

[Explanation of symbols]

201 Quartz Substrate 202 Base Film (Silicon Oxide Film) 203 Amorphous Silicon Film 204 Mask Made of Silicon Oxide Film 205 Opening (Nickel Element Introduction Region) Formed in Mask 206 Nickel Element Held in Contact with Substrate 207 Crystal Growth Direction 208 Crystalline silicon film 209 Thermal oxide film 210 Pattern of silicon film constituting active layer 211 Thermal oxide film 304 Silicon oxide film (CVD oxide film) 305 formed by CVD method Pattern 306 made of aluminum film 306 Resist mask 307 Gate electrode 308 Porous anodic oxide film 309 Dense anodic oxide film 310 Remaining silicon oxide film 311 Source region 312 Low concentration impurity region 313 Channel region 314 Low concentration impurity region 315 Drain region 316 Interlayer insulating film 317 Source Electrode 318 Drain electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication H01L 21/336 H01L 29/78 627G (31) Priority claim number Japanese Patent Application No. 8-32875 (32) Priority Day 8 (1996) January 26 (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 8-32981 (32) Priority Day January 8 (1996) January 27 ( 33) Priority claiming country Japan (JP) (31) Priority claiming number Japanese Patent Application No. 8-58334 (32) Priority date Hei 8 (1996) February 20 (33) Priority claiming country Japan (JP) (31) ) Priority claim number Japanese Patent Application No. 8-88759 (32) Priority date 8 (1996) March 17 (33) Priority claim country Japan (JP) (72) Inventor Jun Koyama 398 Hase, Atsugi, Kanagawa Prefecture Semiconducting Energy Laboratory Co., Ltd. (72) Inventor Yasushi Ogata 398 Hase, Atsugi, Kanagawa Inside the Semiconductor Energy Laboratory (72) Masahiko Hayakawa 398 Hase, Atsugi City, Kanagawa Prefecture Inside the Semiconductor Energy Laboratory, Inc. (72) Inventor Mitsuaki Nono Inside 398 Hase, Atsugi City, Kanagawa Prefecture Inside the Semiconductor Energy Institute (72) Inventor Toshiji Hamaya 398 Hase, Atsugi City, Kanagawa Prefecture, Semiconductor Semiconductor Research Institute, Inc.

Claims (21)

[Claims] 1. A semiconductor device using a thin film transistor having a crystalline silicon film formed on a substrate having an insulating surface as an active layer, the crystalline silicon film having a continuity in a predetermined direction. In the thin film transistor having a structure and having a crystal grain boundary extending in the predetermined direction, the direction connecting the source region and the drain region and the predetermined direction have a predetermined angle. A semiconductor device characterized in that a thermal oxide film having a thickness larger than that of the crystalline silicon film is formed on the crystalline silicon film. 2. A semiconductor device using a thin film transistor having a crystalline silicon film as an active layer formed on a substrate having an insulating surface, wherein the crystalline silicon film is a crystal having continuity in a predetermined direction. Having a structure, and having a crystal grain boundary extending in the predetermined direction, in the thin film transistor, the moving direction of the carriers in the channel region and the predetermined direction have a predetermined angle, A semiconductor device, wherein a thermal oxide film having a thickness larger than that of the crystalline silicon film is formed on the crystalline silicon film. 3. A semiconductor device using a thin film transistor having a crystalline silicon film formed on a substrate having an insulating surface as an active layer, the crystalline silicon film having lattice continuity in a predetermined direction. In the thin film transistor, the crystal structure has a crystal structure, and a crystal structure in which the continuity of the lattice is impaired in a direction perpendicular or substantially perpendicular to the predetermined direction, and a direction connecting a source region and a drain region with the direction. The predetermined direction has a predetermined angle, and a thermal oxide film having a thickness larger than that of the crystalline silicon film is formed on the crystalline silicon film. . 4. A semiconductor device using a thin film transistor having a crystalline silicon film formed on a substrate having an insulating surface as an active layer, the crystalline silicon film having lattice continuity in a predetermined direction. A crystalline structure having, and having a crystalline structure in which the continuity of the lattice is impaired in a direction perpendicular or substantially perpendicular to the predetermined direction, in the thin film transistor, a moving direction of carriers in a channel region and the predetermined direction. Direction has a predetermined angle, and a thermal oxide film having a thickness larger than that of the crystalline silicon film is formed on the crystalline silicon film. 5. A semiconductor device using a thin film transistor having a crystalline silicon film formed on a substrate having an insulating surface as an active layer, the crystalline silicon film being different in the extending direction of crystal grain boundaries. In the thin film transistor, the direction in which the source region and the drain region are connected to each other and the extending direction have a predetermined angle in the thin film transistor. A semiconductor device, wherein a thermal oxide film having a thickness larger than that of a silicon film is formed. 6. A semiconductor device using a thin film transistor having a crystalline silicon film formed on a substrate having an insulating surface as an active layer, wherein the crystalline silicon film is different in the extending direction of crystal grain boundaries. In the thin film transistor, the moving direction of carriers in the channel region and the extending direction have a predetermined angle in the thin film transistor, and the crystalline silicon film has a predetermined angle. A semiconductor device having a thermal oxide film formed thicker than the film. 7. The semiconductor device according to claim 1, wherein the predetermined angle is 0 ° or approximately 0 °. 8. The semiconductor device according to claim 1, wherein a metal element that promotes crystallization of silicon is added to the crystalline silicon film. 9. The nickel (N) is used as a metal element for promoting crystallization of silicon according to claim 8.
A semiconductor device characterized in that i) is utilized. 10. The nickel element according to claim 9, wherein the nickel element is 1 ×
A semiconductor device characterized by being contained at a concentration of 10 ¹⁴ atoms / cm ^{3 to} 5 × 10 ¹⁸ original. 11. The nickel element according to claim 9, wherein the nickel element is 1 ×
A semiconductor device characterized by being contained at a concentration of 10 ¹⁶ atoms / cm ^{3 to} 5 × 10 ¹⁷ atoms / cm ³ . 12. The metal element for promoting crystallization of silicon according to claim 8, Fe, Co,
Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, A
A semiconductor device characterized in that one or more kinds selected from u are used. 13. The metal element according to claim 8, wherein the metal element that promotes crystallization of silicon has a concentration distribution in which the content concentration increases toward the front surface and / or the back surface of the crystalline silicon film. Semiconductor device. 14. The crystalline silicon film according to claim 8, wherein the crystalline silicon film contains a halogen element, and the halogen element has a concentration distribution in which the content concentration increases toward the front surface and / or the back surface of the crystalline silicon film. A semiconductor device having: 15. A semiconductor device according to claim 1, wherein the crystalline silicon film has a film thickness of 100Å to 750Å. 16. A step of forming an amorphous silicon film on a substrate having an insulating surface, and a step of selectively introducing a metal element that partially promotes crystallization of silicon into the amorphous silicon film. And a step of performing heat treatment to perform crystal growth in a direction parallel to the substrate from the region where the metal element is selectively introduced to another region, and in a oxidizing atmosphere containing a halogen element. A step of forming a first thermal oxide film by heat treatment, a step of removing the first thermal oxide film, and a step of forming a second thermal oxide film in an oxidizing atmosphere containing a halogen element. And a film thickness of the finally obtained silicon film is thinner than the film thickness of the second thermal oxide film. 17. A step of forming an amorphous silicon film on a substrate having an insulating surface, and a step of selectively introducing a metal element that partially promotes crystallization of silicon into the amorphous silicon film. And a step of performing heat treatment to perform crystal growth in a direction parallel to the substrate from the region where the metal element is selectively introduced to another region, and in a oxidizing atmosphere containing a halogen element. 800 ° C
A step of forming a first thermal oxide film by heat treatment at ˜1100 ° C., a step of removing the first thermal oxide film, and a temperature of 800 ° C. in an oxidizing atmosphere containing a halogen element.
A step of forming a second thermal oxide film by a heat treatment at ˜1100 ° C., and the thickness of the finally obtained silicon film is smaller than that of the second thermal oxide film. A method for manufacturing a characteristic semiconductor device. 18. A step of forming an amorphous silicon film on a substrate having an insulating surface, and a step of selectively introducing a metal element that promotes crystallization of silicon into a part of the amorphous silicon film. And a step of performing heat treatment to perform crystal growth in a direction parallel to the substrate from the region where the metal element is selectively introduced to another region, and in a oxidizing atmosphere containing a halogen element. A step of forming a first thermal oxide film by heat treatment, a step of removing the first thermal oxide film, and a step of forming a second thermal oxide film in an oxidizing atmosphere containing a halogen element. And the film thickness of the finally obtained silicon film is smaller than the total film thickness of the first thermal oxide film and the second thermal oxide film. . 19. A step of forming an amorphous silicon film on a substrate having an insulating surface, and a step of selectively introducing a metal element that partially promotes crystallization of silicon into the amorphous silicon film. And a step of performing heat treatment to perform crystal growth in a direction parallel to the substrate from the region where the metal element is selectively introduced to another region, and in a oxidizing atmosphere containing a halogen element. 800 ° C
A step of forming a first thermal oxide film by heat treatment at ˜1100 ° C., a step of removing the first thermal oxide film, and a temperature of 800 ° C. in an oxidizing atmosphere containing a halogen element.
A step of forming a second thermal oxide film by heat treatment at ˜1100 ° C., and the film thickness of the finally obtained silicon film is the same as the first thermal oxide film and the second thermal oxide film. A method for manufacturing a semiconductor device, which is thinner than a total film thickness. 20. The nickel (N) element according to claim 16, which is used as a metal element for promoting crystallization of silicon.
i) A method for manufacturing a semiconductor device, characterized in that the method is used. 21. The metal element for promoting crystallization of silicon according to claim 16, wherein Fe, Co,
Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, A
A method for manufacturing a semiconductor device, characterized in that one or more kinds selected from u are used.