JP3464287B2 - Method for manufacturing semiconductor device - Google Patents

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 device using a semiconductor having crystallinity.

[0002]

2. Description of the Related Art A thin film transistor (hereinafter referred to as TFT) using a thin film semiconductor is known. In this TFT, a thin film semiconductor is formed on a substrate, and an active region is formed by using this thin film semiconductor. Although this TFT is used in various integrated circuits, it is particularly noted as a switching element provided in each pixel of an electro-optical device, particularly an active matrix liquid crystal display device, and a driver element formed in a peripheral circuit portion. There is.

As a thin film semiconductor used for TFT,
Although it is easy to use an amorphous silicon film, there is a problem in that its electrical characteristics are low. In order to improve the characteristics of the TFT, a crystalline silicon thin film may be used. A crystalline silicon film is referred to as polycrystalline silicon, polysilicon, microcrystalline silicon, or the like. In order to obtain this crystalline silicon film, an amorphous silicon film may first be formed and then crystallized by heating.

However, crystallization by heating requires heating at a temperature of 600 ° C. or higher for 10 hours or longer, which makes it difficult to use a glass substrate as a substrate. For example, Corning 7059 glass used in an active type liquid crystal display device has a glass strain point of 593 ° C., and there is a problem in heating at 600 ° C. or higher in consideration of increasing the area of a substrate.

BACKGROUND OF THE INVENTION According to the research conducted by the present inventors, a small amount of elements such as nickel, palladium, and lead are deposited on the surface of an amorphous silicon film, and then heated to 550. It has been found that crystallization can be performed in a treatment time of about 4 hours at ℃.

In order to introduce such a trace amount of elements (metal elements that promote crystallization), plasma treatment, vapor deposition, or ion implantation may be used. Plasma treatment is to generate plasma in an atmosphere such as nitrogen or hydrogen in a parallel plate type or positive column type plasma CVD apparatus using a material containing a metal element (for example, nickel) that promotes crystallization as an electrode. Is a method of adding a metal element to the amorphous silicon film.

However, the presence of a large amount of the above-mentioned elements in the semiconductor impairs the reliability and electrical stability of the device using these semiconductors and is not preferable.

That is, the above-mentioned element (metal element) that promotes crystallization, such as nickel, is necessary when crystallizing amorphous silicon, but the crystallized silicon should not be included as much as possible. Is desirable. To achieve this goal,
It is necessary to select a metal element having a strong tendency to be inactive in crystalline silicon as well as to minimize the amount of the metal element required for crystallization and perform crystallization with the minimum amount. For that purpose, it is necessary to precisely control the amount of the metal element added and to introduce the metal element.

When nickel is used as a metal element, an amorphous silicon film is formed, nickel is added by a plasma treatment method to form a crystalline silicon film, and the crystallization process and the like are examined in detail. However, the following matters were found. (1) When nickel is introduced into the amorphous silicon film by the plasma treatment, nickel has already penetrated to a considerable depth in the amorphous silicon film before the heat treatment. (2) The initial nucleation of crystals occurs from the surface into which nickel is introduced. (3) Even when nickel is formed on the amorphous silicon film by the vapor deposition method, crystallization occurs as in the case of performing the plasma treatment.

From the above it is concluded that all the nickel introduced by the plasma treatment is not functioning effectively. That is, it is considered that there is nickel that does not function sufficiently even if a large amount of nickel is introduced. From this, it is considered that the point (plane) where nickel and silicon are in contact functions during low temperature crystallization.
Then, it is concluded that nickel should be dispersed as finely as possible in atomic form. That is, it is concluded that "it is necessary to disperse nickel as atomically as possible in a concentration as low as possible within the range where low temperature crystallization is possible near the surface of the amorphous silicon film."

As a method of introducing a very small amount of nickel only in the vicinity of the surface of the amorphous silicon film, in other words, a very small amount of a metal element that promotes crystallization only in the vicinity of the surface of the amorphous silicon film. , Vapor deposition method can be mentioned,
The vapor deposition method has poor controllability and has a problem that it is difficult to strictly control the introduction amount of the metal element. It is also possible to use an ion implantation method or a plasma doping method, but there is a problem in terms of productivity.

[0012]

DISCLOSURE OF THE INVENTION The present invention is directed to the production of a crystalline thin film silicon semiconductor by heat treatment at 600 ° C. or lower using a metal element. Minimize the amount. (2) Use a method with high productivity. (3) Obtain a crystalline silicon thin film intended for use in a device. The purpose is to meet such requirements.

[0013]

One of the constitutions of the present invention is as follows.
A step of selectively forming a mask on the surface of the amorphous silicon film; a step of holding a metal element that promotes crystallization of silicon in contact with the surface of the amorphous silicon film;
Alternatively, a step of crystallizing the amorphous silicon film by performing light irradiation is included.

According to another aspect of the invention, a step of selectively forming a mask on the surface of the amorphous silicon film and a metal element for promoting crystallization of silicon are selectively formed on the surface of the amorphous silicon film. And a step of holding them in contact with each other, and by performing heat treatment and / or light irradiation, crystal growth of the amorphous silicon film is performed from a region in which the metal element is held in contact to a region in which the metal element is not in contact. And a step of adding.

According to another aspect of the invention, a step of selectively forming a mask on the surface of an amorphous silicon film formed on a substrate having an insulating surface, and a crystal of silicon on the surface of the amorphous silicon film. A step of selectively contacting and holding a metal element that promotes chemical conversion, and performing heat treatment and / or light irradiation to perform crystal growth in a direction parallel to the substrate from the area where the metal element is held in contact. And a process.

By adopting the configuration of the present invention, the following basic significance can be obtained. (A) The concentration of the metal element in the solution can be strictly controlled beforehand to enhance the crystallinity and reduce the amount of the element. (B) If the solution is in contact with the surface of the amorphous silicon film,
The amount of the metal element introduced into the amorphous silicon depends on the concentration of the metal element in the solution. (C) Since the metal element adsorbed on the surface of the amorphous silicon film mainly contributes to crystallization, the metal element can be introduced at a required minimum concentration. (D) By selectively introducing the metal element using the mask, crystal growth can be performed from the region into which the metal element has been introduced to the region into which the metal element has not been introduced.

As a method for applying a solution containing an element that promotes crystallization to the amorphous silicon film, an aqueous solution, an organic solvent solution or the like can be used as the solution. Here, the inclusion includes both the meaning of being contained as a compound and the meaning of being contained by simply dispersing.

As the solvent containing a metal element, a solvent selected from polar solvents such as water, alcohol, acid and ammonia can be used.

When nickel is used as the catalyst and this nickel is included in the polar solvent, nickel is introduced as a nickel compound. The nickel compound is typically nickel bromide, nickel acetate, nickel oxalate, nickel carbonate, nickel chloride, nickel iodide, nickel nitrate, nickel sulfate, nickel formate, nickel acetylacetonate, 4-cyclohexyl butyric acid. A material selected from nickel, nickel oxide, and nickel hydroxide is used.

Further, as a solvent containing a metal element, benzene, toluene, xylene, carbon tetrachloride, which are nonpolar solvents,
It is possible to use one selected from chloroform and ether.

In this case, nickel is introduced as a nickel compound. As the nickel compound, one selected from nickel acetylacetonate and nickel 2-ethylhexanoate can be typically used.

It is also useful to add a surfactant to the solution containing the metal element. This is to enhance the adhesion to the surface to be coated and control the adsorptivity. This surfactant may be applied on the surface to be coated in advance.

When nickel alone is used as the metal element, it must be dissolved in acid to form a solution.

The above is an example of using a solution in which nickel, which is a metal element, is completely dissolved. However, even if nickel is not completely dissolved, a powder of nickel alone or a nickel compound is in a dispersion medium. A material such as an emulsion uniformly dispersed in the above may be used.

The same applies to the case where a material other than nickel is used as the metal element.

When nickel is used as a metal element that promotes crystallization and a polar solvent such as water is used as a solution solvent containing nickel, when these solutions are directly applied to the amorphous silicon film, the solution becomes elastic. You may get burned. In this case, a thin oxide film having a thickness of 100 Å or less is first formed, and a solution containing a metal element is applied thereon, whereby the solution can be uniformly applied. A method of improving wetting by adding a material such as a surfactant to the solution is also effective.

Further, by using a non-polar solvent such as a toluene solution of nickel 2-ethylhexanoate as a solution, it is possible to apply directly to the surface of the amorphous silicon film. In this case, it is effective to pre-apply a material such as an adhesive used when applying the resist. However, if the coating amount is too large, the addition of the metal element to the amorphous silicon will be hindered, and therefore caution must be exercised.

The amount of the metal element contained in the solution depends on the kind of the solution, but as a general tendency, the amount of nickel is 200 ppm to 1 ppm, preferably 50 ppm to 1 ppm (weight conversion) with respect to the solution. Is desirable. This is a value determined in consideration of the nickel concentration in the film and the hydrofluoric acid resistance after completion of crystallization.

The concentration of the metal element in the solution is 1 × 10 5 (evaluated by the nickel concentration in the crystalline silicon film finally obtained) introduced into the amorphous silicon film. ^It may be determined to be ^{16 to} 5 × 10 ¹⁹ atoms cm ⁻³ . The concentration of the metal element introduced into the amorphous silicon film can also be controlled by the holding time of the solution. The concentration of the metal element in this specification is S
The minimum value evaluated by IMS (secondary ion analysis method).

Further, by selectively applying a solution containing a metal element, crystal growth can be selectively performed. In this case, in particular, crystal growth is performed in the direction substantially parallel to the surface of the silicon film (the direction parallel to the substrate on which the silicon film is formed) from the area to which the solution has not been applied. be able to. In this specification, a region in which crystal growth is performed in a direction substantially parallel to the surface of the silicon film is referred to as a lateral crystal growth region.

It has been confirmed that the concentration of the metal element is low in the region where the crystal growth is performed in the lateral direction.
Although it is useful to use a crystalline silicon film as the active layer region of the semiconductor device, it is generally preferable that the concentration of impurities in the active layer region is low. Therefore, forming the active layer region of the semiconductor device by using the region in which the crystal growth is performed in the lateral direction is useful for device fabrication.

Further, in this laterally crystal-grown region, crystal grain boundaries exist along the crystalline growth direction.
When the structure is such that the carriers move along with the crystal growth, scattering and trapping of carriers by the crystal grain boundaries can be reduced. That is, the characteristics of the device can be improved.

In the present invention, the most remarkable effect can be obtained when nickel is used as the metal element, but other types of metal elements that can be used include Fe and
Co, Ru, Rh, Pd, Os, Ir, Pt, Cu, A
One or more elements selected from u can be used.

The method of introducing the metal element is not limited to the use of an aqueous solution or a solution such as alcohol, but a wide range of substances containing the metal element can be used.
For example, a metal compound or oxide containing a metal element can be used.

By using the crystalline silicon film obtained by the present invention, it is possible to obtain a semiconductor device forming an active region having at least one electrical junction such as PN, PI, NI. Examples of such a semiconductor device include a thin film transistor (TFT), a diode, and an optical sensor.

[0036]

【Example】

[Example 1]

This embodiment is an example in which a metal element that promotes crystallization is contained in an aqueous solution, coated on an amorphous silicon film, and then heated to be crystallized. First, referring to FIG. 1, description is made up to the point of introducing a metal element (here, nickel is used). In this embodiment, Corning 7059 glass is used as the substrate. The size is 100 mm × 100 mm.

First, the amorphous silicon film is formed by plasma CVD or LPCVD to form an amorphous silicon film having a thickness of 100Å to 150.
Form a film with a thickness of 0Å. Here, the amorphous silicon film 12 is formed to a thickness of 1000 Å by the plasma CVD method. (Fig. 1 (A))

Then, a hydrofluoric acid treatment is carried out to remove dirt and a natural oxide film, and then the oxide film 13 is removed by 10 to 50.
Deposit on Å. Needless to say, this step may be omitted if the stain can be ignored, and a natural oxide film may be used as it is instead of the oxide film 13. Since the oxide film 13 is extremely thin, the exact film thickness is unknown.
It is considered to be about 0Å. Here, the oxide film 13 is formed by irradiation with UV light in an oxygen atmosphere. The film forming condition is performed by irradiating UV for 5 minutes in an oxygen atmosphere. As a method of forming the oxide film 13, a thermal oxidation method may be used. Alternatively, treatment with hydrogen peroxide may be used.

The oxide film 13 is provided to spread the acetate solution over the entire surface of the amorphous silicon film, that is, to improve the wettability in the subsequent step of applying the acetate solution containing nickel. Is. For example, when the acetate solution is directly applied to the surface of the amorphous silicon film, the amorphous silicon repels the acetate solution, so that nickel cannot be introduced to the entire surface of the amorphous silicon film. That is, uniform crystallization cannot be performed.

Next, an acetate solution is prepared by adding nickel to the acetate solution. The concentration of nickel is 100 ppm. Then, 2 ml of this acetate solution is dropped on the surface of the oxide film 13 on the amorphous silicon film 12, and this state is maintained for 5 minutes. Then spin dry (2000
rpm, 60 seconds). (Fig. 1 (C), (D))

The concentration of nickel in the acetic acid solution is 1
Practical use is achieved when the content is at least ppm, preferably at least 10 ppm. When a nonpolar solvent such as a toluene solution of nickel 2-ethylhexanoate is used as the solution, the oxide film 1
3 is unnecessary, and the metal element can be directly introduced onto the amorphous silicon film.

A layer containing nickel having an average film thickness of several Å to several hundred Å is formed on the surface of the amorphous silicon film 12 after spin drying by performing this nickel solution coating step once or plural times. Can be formed. In this case, nickel in this layer diffuses into the amorphous silicon film in the subsequent heating step and promotes crystallization. Note that this layer is not necessarily a perfect film. In this way, nickel element is introduced into the amorphous silicon film.

After the application of the above solution, the state is maintained for 5 minutes. The concentration of nickel contained in the silicon film 12 can be finally controlled also by the holding time, but the largest control factor is the concentration of the solution.

Then, in a heating furnace, heat treatment is performed at 550 ° C. for 4 hours in a nitrogen atmosphere. As a result,
It is possible to obtain the crystalline silicon thin film 12 formed on the substrate 11.

The above heat treatment can be carried out in the temperature range of 450 ° C. to 750 ° C. However, if the temperature is low, the heating time must be lengthened and the production efficiency will be reduced. Further, when the temperature is 600 degrees or more, the problem of heat resistance of the glass substrate used as the substrate is exposed. Therefore, when a glass substrate is used as the substrate, the temperature of the heat treatment step is preferably performed in the range of 450 ° C to 600 ° C.

Although an example of performing the heat treatment is shown here, laser light irradiation or intense light irradiation may be performed in combination with the heat treatment or instead of the heat treatment. For example, a method of performing irradiation with laser light or intense light before or after heat treatment, a method of performing heat treatment after irradiation with laser light or intense light, irradiation with laser light or intense light after heat treatment, and further heat treatment And a method of heating at the same time as irradiation with laser light or intense light. The heat treatment referred to here is 450 ° C to 750 ° C.
℃, considering the heat resistance of the glass substrate 450 ℃ ~ 6
It is desirable to carry out at a temperature of 00 ° C.

In this embodiment, the method of introducing the metal element onto the amorphous silicon film is shown, but the method of introducing the metal element below the amorphous silicon film may be adopted. in this case,
The metal element may be introduced onto the base film using a solution containing the metal element before forming the amorphous silicon film. Then, an amorphous silicon film is formed on the base film into which the metal element is introduced,
After that, heat treatment or laser light irradiation may be performed.

[Embodiment 2] This embodiment relates to an example in which a mask for selectively introducing nickel is provided in the manufacturing method shown in Embodiment 1. Specifically, this is an example in which a 1200 Å silicon oxide film is selectively provided and nickel is selectively introduced using this silicon oxide film as a mask.

FIG. 2 shows an outline of the manufacturing process in this embodiment. First, the glass substrate (Corning 7059, 10c
A silicon oxide film 21 serving as a mask is formed on the (m square) to a thickness of 1000 Å or more, here 1200 Å. The film thickness of the silicon oxide film 21 is 5 according to experiments by the inventors.
It has been confirmed that there is no problem even with 00Å, and if the film quality is dense, it may be possible to make it thinner.

Then, the silicon oxide film 21 is patterned into a required pattern by a normal photolithographic patterning process. Then, a thin silicon oxide film 20 is formed by irradiation of ultraviolet rays in an oxygen atmosphere. This silicon oxide film 2
Production of 0 is performed by irradiating UV light for 5 minutes in an oxygen atmosphere. The thickness of the silicon oxide film 20 is considered to be about 20 to 50Å (FIG. 2 (A)). still,
The silicon oxide film for improving the wettability may be added just by the hydrophilicity of the silicon oxide film of the mask only when the size of the solution and the pattern match. However, such an example is special, and it is generally safer to use the silicon oxide film 20.

In this state, as in Example 1, 10
5 ml of an acetate solution containing 0 ppm of nickel is dropped (in the case of a 10 cm square substrate). At this time, spin coating is performed with a spinner at 50 rpm for 10 seconds to form a uniform water film on the entire surface of the substrate. After maintaining this state for 5 minutes, spin drying is performed at 2000 rpm for 60 seconds using a spinner. This holding may be performed while rotating the spinner at 0 to 150 rpm. (Fig. 2 (B))

Then, the amorphous silicon film 12 is crystallized by performing heat treatment at 550 ° C. (nitrogen atmosphere) for 4 hours. At this time, crystal growth is performed in the lateral direction from the region where nickel is introduced to the region where nickel is not introduced, as shown by an arrow 23. Figure 2
In (C), 24 is a region where nickel is directly introduced and crystallized, and 25 is a region where lateral crystallization is performed. In addition, it has been confirmed that crystal growth is performed in the region of 25 in the direction of substantially the <111> axis.

In the present embodiment, by changing the solution concentration and the holding time, the nickel concentration in the region where nickel was directly introduced can be controlled within an arbitrary range. Similarly, the concentration of the lateral growth region can be controlled to be lower than that. The concentration of the metal element remaining in the silicon film is 1 × 10 ¹⁶ atoms cm ^{−3 to} 5 × 10 ¹⁹ atoms cm ^−3.
It is preferably within the range. This is 1 × 10 ¹⁶ at
If the concentration is oms cm ⁻³ or less, the effect of promoting crystallization cannot be obtained, and if the concentration is 5 × 10 ¹⁹ atoms cm ⁻³ or more, the characteristics as a semiconductor are deteriorated due to the influence of the metal element. Because it will be hindered.

As described above, the region in which the crystal has grown in the lateral direction has a low concentration of the metal element and has good crystallinity. Therefore, it is useful to use this region as the active region of the semiconductor device. In particular, with a structure in which carriers move in the crystal growth direction, for example, a thin film transistor having high mobility can be obtained.

In this embodiment, an example in which a silicon oxide film is used as a mask used when selectively introducing nickel into the amorphous silicon film is shown. But as a mask,
A resin material such as silicon nitride, aluminum oxide, aluminum nitride, a resist, or other insulating material can be used. Of course, since it is a mask material for selectively introducing a metal element, it is required to be a dense and pinhole-free material. Further, as the mask, not a single layer film but a multilayer film of an oxide film and a silicon nitride film, or a film whose components are changed in the thickness direction of the film may be used.

[Embodiment 3] This embodiment is an example in which nickel, which is a metal element, is contained in alcohol, which is a non-aqueous solution, and is coated on an amorphous silicon film. In this embodiment, nickel acetylacetonate is used as a nickel compound, and the compound is contained in alcohol. The concentration of nickel may be the required concentration.

The subsequent steps are the same as those shown in the first or second embodiment. Further, the alcohol solution containing nickel may be applied under the amorphous silicon film. In this case, this solution may be applied using a spinner before forming the amorphous silicon film. When alcohol is used, it can be directly coated on the amorphous silicon film.

Specific conditions will be described below. First, nickel acetylacetonate is prepared as a nickel compound. Since this substance is soluble in alcohol and has a low decomposition temperature, it can be easily decomposed during heating in the crystallization step.

Further, ethanol is used as the alcohol. First, the nickel acetylacetonate is adjusted to 100 ppm in ethanol in terms of the amount of nickel to prepare a solution containing nickel.

Then, this solution is applied onto the amorphous silicon film. The amorphous silicon film is a silicon oxide base film (200
1 on a 100 mm square glass substrate with 0 Å thickness)
It is formed by a plasma CVD method with a thickness of 000Å.

The application of the solution onto the amorphous silicon film is less than that in the case of using the aqueous solutions of Example 1 and Example 2. This is because the contact angle of alcohol is smaller than that of water. Here, 2 ml is dropped on an area of 100 mm square.

Then, this state is maintained for 5 minutes. After that, it is dried using a spinner. At this time, the spinner is 1
Rotate at 500 rpm for 1 minute. After this, 550
Crystallization is performed by heating at ℃ for 4 hours. Thus, a crystalline silicon film is obtained.

[Embodiment 4] This embodiment is an example in which a simple substance of nickel which is a metal element is dissolved in an acid and the acid in which the simple substance of nickel is dissolved is applied onto an amorphous silicon film.

In the present embodiment, the acid is 0.1 mo.
1 / l nitric acid is used. Dissolve nickel powder in this nitric acid so that the concentration of nickel becomes 50 ppm,
This is used as a solution. The subsequent steps are the same as those in the first embodiment.

[Embodiment 5] In this embodiment, as shown in Embodiment 2, nickel is selectively introduced, and electrons are emitted from the region where crystals are grown laterally (parallel to the substrate). An example of forming a device is shown. When such a structure is adopted, the nickel concentration in the active layer region of the device can be further lowered, and the structure can be made extremely preferable in terms of electrical stability and reliability of the device. Further, by making the crystal growth direction coincide with or substantially coincide with the carrier movement direction, it is possible to make the structure in which the carrier movement is hardly influenced by the existence of the crystal grain boundaries, and to obtain a high-performance device. .

This example relates to a process of manufacturing a TFT used for controlling an active matrix pixel. FIG. 3 shows the manufacturing process of this embodiment. First, the substrate 20
1 is washed, and TEOS (tetra-ethoxy-silane) and oxygen are used as source gases to form a plasma-deposited film having a thickness of 2
A base film 202 of 000Å silicon oxide is formed.

Then, plasma CVD method or reduced pressure heat C
According to the VD method, the thickness is 500 to 1500Å, for example, 10
An intrinsic (I-type) amorphous silicon film 203 of 00Å is formed. Next, the thickness is continuously 500 to 2000Å, for example, 10
A 00Å silicon nitride film 205 is formed by a plasma CVD method. Here, the silicon nitride film functions as a mask when a metal element (using nickel) that promotes later crystallization is introduced.

Then, the silicon oxide film 205 is selectively etched to form an exposed region 206 of amorphous silicon. That is, a mask is formed.

Then, a solution (here, an acetate solution) containing nickel element which is a metal element for promoting crystallization is applied. The concentration of nickel in acetic acid solution is 100 pp
m. In addition, the detailed process order and conditions are the same as those shown in the second embodiment. The water film 207 is obtained by applying the nickel acetate solution.

After this, in a nitrogen atmosphere, 450 to 600
Anneal at ℃, here 550 ℃ for 4 hours,
The silicon film 303 is crystallized. Crystallization proceeds from a region 206 where the nickel film and the silicon film are in contact with each other as a starting point, and crystal growth proceeds in a direction parallel to the substrate as indicated by an arrow. The crystal growth in the lateral direction is about 25 μm.
It has been confirmed that the crystal growth direction is approximately the <111> axis direction. (Fig. 3 (A))

Next, the silicon nitride film 205 functioning as a mask is removed. At this time, the oxide film formed on the surface of the region 206 is also removed at the same time. Then, the silicon film 204
Is patterned and then dry-etched to form an island-shaped active layer region 208.

Here, the region indicated by 206 in FIG. 3A is a region into which nickel is directly introduced, and is a region in which nickel is present at a high concentration. It has also been confirmed that nickel also exists at a high concentration at the tip of crystal growth. It has been found that the nickel concentration in these regions is higher than that in the intermediate region. Therefore, in the present embodiment, in the active layer 208, these regions having a high nickel concentration are prevented from overlapping the channel formation region.

After that, a silicon oxide film 209 functioning as a gate insulating film is formed to a thickness of 1000 Å by plasma CVD. (Fig. 3 (B))

Subsequently, by the sputtering method,
A film of aluminum (containing 0.01 to 0.2% scandium) having a thickness of 3000 to 8000Å, for example, 6000Å is formed. Then, the aluminum film is patterned to form the gate electrode 210. (Fig. 3 (C))

Further, the surface of the aluminum electrode is anodized to form an oxide layer 211 on the surface. This anodic oxidation is performed by using the gate electrode 210 as an anode in an ethylene glycol solution containing 1 to 5% tartaric acid. The resulting oxide layer 211 has a thickness of 2000Å. In addition,
Since this oxide 211 has a thickness that forms an offset gate region in a later ion doping step,
The length of the offset gate region can be determined by the above anodic oxidation process. (Fig. 3 (D))

Next, the gate electrode portion, that is, the gate electrode 210 and the oxide layer 211 around it is used as a mask in the active layer region (which constitutes the source / drain and the channel) by an ion doping method (also called a plasma doping method). An impurity (here, phosphorus) that imparts the N conductivity type is added in a self-aligning manner. Phosphine (PH ₃ ) is used as the doping gas, and the acceleration voltage is set to 60 to 90 kV, for example, 80 kV. Dose amount is 1 × 10 ¹⁵ to 8 × 10
^{It is set to 15} cm ^-2 , for example, 4 × 10 ¹⁵ cm ^-2 . As a result, N type impurity regions 212 and 213 are formed. As is clear from the figure, the impurity region and the gate electrode are in an offset state separated by a distance x. Such an offset state causes a reverse voltage (N-channel TF) especially on the gate electrode.
In the case of T, it is effective in reducing the leak current (also referred to as off current) when a minus is applied. In particular, as in this embodiment, T for controlling the pixels of the active matrix
In the FT, it is desired that the leak current is low so that the charge accumulated in the pixel electrode does not escape in order to obtain a good image, and therefore it is effective to provide the offset.

After that, annealing is performed by irradiation with laser light. As the laser light, a KrF excimer laser (wavelength 248 nm, pulse width 20 nsec) is used, but other laser may be used. The laser light irradiation conditions are energy density of 200 to 400 mJ / cm ² ,
For example, 250 mJ / cm ² and ² to 10 per place
Irradiate a shot, for example, two shots. The effect may be increased by heating the substrate to about 200 to 450 ° C. during the irradiation of the laser light. (Fig. 3 (E))

Then, a silicon oxide film 21 having a thickness of 6000Å is formed.
4 as an interlayer insulator is formed by the plasma CVD method. Further, a transparent polyimide film 215 is formed by spin coating to flatten the surface. A thickness of 80 is formed on the flat surface thus formed by the sputtering method.
A 0 Å transparent conductive film (ITO film) is formed and patterned to form a pixel electrode 216.

Then, contact holes are formed in the interlayer insulators 214 and 215, and electrodes / wirings 217 and 218 of the TFT are formed by a metal material, for example, a multilayer film of titanium nitride and aluminum. Finally, annealing is performed at 350 ° C. for 30 minutes in a hydrogen atmosphere of 1 atm to complete an active matrix pixel circuit having TFTs. (Fig. 3
(F))

[Embodiment 6] This embodiment shows an example in which the present invention is applied to an active matrix type liquid crystal display device. FIG. 5 is a top view showing an outline of one substrate of the active matrix type liquid crystal display device of FIG. 4.

In the figure, 61 is a glass substrate, and 6
Reference numeral 2 is a pixel region configured in a matrix, and several hundreds × several hundreds of pixels are formed in the pixel region. A TFT is arranged as a switching element in each of the pixels. The driver TFT for driving the TFT in this pixel area is arranged in the peripheral driver area 6
It is 2. The pixel region 63 and the driver region 62 are integrally formed on the same substrate 61.

The TFT arranged in the driver region 62 needs to flow a large current, and high mobility is required.
Further, since the TFT arranged in the pixel region 63 needs to increase the charge retention rate of the pixel electrode, it is required to have a characteristic that the off current (leakage current) is small. For example, as the TFT arranged in the pixel region 63, the TFT shown in FIG. 3 can be used.

[0084]

[Effect] By manufacturing a semiconductor device using a crystalline silicon film in which a metal element is introduced and crystallized at low temperature in a short time, a device with high productivity and excellent characteristics can be obtained.

[Brief description of drawings]

FIG. 1 shows a process of an example.

FIG. 2 shows a process of an example.

FIG. 3 shows a manufacturing process of an example.

FIG. 4 shows a configuration of an example.

[Explanation of symbols]

11 ... Glass substrate 12 ... Amorphous silicon film 13 ··· Silicon oxide film 14 ... Acetic acid solution film containing nickel 15 ... Zpiner 21..Silicon oxide film for mask 20 ... Silicon oxide film 201 ... Glass substrate 202 ... Base film 203 ... Active layer 204 ... Silicon film 205 ... Mask (silicon nitride film) 207 ... Water film (nickel acetate solution) 208 ... Active layer 209 ... Gate insulating film 210: Gate electrode 211 ... Anodic oxide layer 212 ... Source / drain regions 213 ... Drain / source region 214 ... Interlayer insulating film (silicon oxide film) 215 ... Polyimide film 216 ... Pixel electrode (ITO) 217 ... Electrode 218 ... Electrode

Continuation of the front page (56) Reference JP-A-2-305475 (JP, A) JP-A-63-56912 (JP, A) JP-A-6-244105 (JP, A) JP-A-6-232059 (JP , A) JP-A-5-67635 (JP, A) JP-A-7-176479 (JP, A) JP-A-7-192998 (JP, A) European Patent Application Publication 612102 (EP, A1) European Patent Application Publication 609867 (EP, A 1) Appl. Phys. Lett. , 55 (7), p. 660-662 JAPANESE JOURNAL OF APPLIED PHYSIC S, 29 (12), p. 2698-2704 (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/20 H01L 21/336 H01L 27/12 H01L 29/786

Claims (16)

(57) [Claims] 1. A mask is formed on the amorphous silicon film to selectively expose the amorphous silicon film, and an oxide film is formed on the exposed portion of the amorphous silicon film, A solution containing a metal element that promotes crystallization of silicon is applied on the amorphous silicon film through the mask and the oxide film, the amorphous silicon film is irradiated with light, and the amorphous silicon film is exposed through the oxide film. The amorphous silicon film is crystal-grown in a direction parallel to the surface of the silicon film from the region coated with the solution to form a crystalline silicon film, and the crystalline silicon film is patterned and then etched. the active layer is formed Te, wherein the region and the crystal growth tip the solution is applied through the oxide film, a method for manufacturing a semiconductor device which is not provided a channel forming region of the active layer the mask is to become aluminum nitride The method for manufacturing a semiconductor device according to symptoms. 2. A mask is formed on the amorphous silicon film, and
The amorphous silicon film is selectively exposed, and an oxide film is formed on the exposed portion of the amorphous silicon film.
The amorphous silicon film through the mask and the oxide film.
A solution containing a metal element that promotes crystallization of silicon is applied on top
Then, the amorphous silicon film is irradiated with light, and the amorphous silicon film is exposed through the oxide film.
One parallel to the surface of the silicon film from the area where the solution is applied
In the opposite direction, the amorphous silicon film is crystal-grown to obtain crystalline silicon.
After forming an elemental film and patterning the crystalline silicon film, etching is performed.
To form the active layer, and the area where the solution is applied through the oxide film and the front surface.
The channel formation region of the active layer is formed at the tip of the crystal growth.
A method of manufacturing a semiconductor device, wherein the mask is made of aluminum oxide.
Manufacturing method of semiconductor device. Wherein said metal element method for manufacturing a semiconductor device according to claim 1 or claim 2, wherein the nickel. 4. The metal element is Fe, Co, Ni, R
3. The method for manufacturing a semiconductor device according to claim 1 , wherein the semiconductor device is u, Rh, Pd, Os, Ir, Pt, Cu, or Au. 5. The concentration of the metal element in the crystalline silicon film is 1 × 10 ¹⁶ atoms · cm ^{−3 to} 5 × 10 ¹⁹ atoms.
- The method for manufacturing a semiconductor device according to any one of claims 1 to 4, characterized in that cm ^-3. 6. The method for manufacturing a semiconductor device according to any one of claims 1 to 5, characterized in that the light irradiation is irradiation of intense light. 7. The method for manufacturing a semiconductor device according to any one of claims 1 to 5, characterized in that the light irradiation is a laser light irradiation. 8. The method for manufacturing a semiconductor device according to any one of claims 1 to 7, wherein the thickness of the oxide film is 10 nm or less. 9. The method for manufacturing a semiconductor device according to any one of claims 1 to 8, characterized in that applying the solution using a spinner. 10. A method for manufacturing a semiconductor device according to any one of claims 1 to 9, characterized by using a polar solvent as the solvent of said solution. 11. The concentration of the metal element in the solution is 2
It is 00 ppm-1 ppm, It is characterized by the above-mentioned.
11. The method for manufacturing a semiconductor device according to any one of items 10 to 10 . 12. The concentration of the metal element in the solution is 5
It is 0 ppm-1 ppm, The manufacturing method of the semiconductor device of any one of Claim 1 to 10 characterized by the above-mentioned. 13. The method for manufacturing a semiconductor device according to any one of claims 1 to 12, wherein the heat treatment is performed after the light irradiation. 14. The method for manufacturing a semiconductor device according to any one of claims 1 to 12, characterized in that at the same time heat treatment and the light irradiation. 15. The semiconductor device is a thin film transistor,
The method for manufacturing a semiconductor device according to any one of claims 1 to 14, characterized in that a diode or photosensor. 16. A method according to claim 1 to 15 active-matrix liquid crystal display device, characterized in that it comprises a semiconductor device manufactured by the manufacturing method according to any one of.