JPH07335548A - Method for manufacturing crystallizability semiconductor - Google Patents

Abstract

PURPOSE:To control the small amount of crystallizability catalyst element, introduce it uniformly, and to improve the productivity by introducing the steam or gas of an organic metal with a catalyst element for promoting the crystallizability of amorphous silicon film into a chamber where a substrate with the amorphous silicon film is laid out and performing thermal decomposition and depositing and performing heat treatment. CONSTITUTION:Silicon oxide film 12 is formed on a substrate 11 and amorphous silicon film 13 is formed by the plasma CVD method and then the substrate 11 is installed in a chamber 101. Then, air is exhausted from the inside of the chamber, a heater 104 is energized, the substrate is heated to 500-550 deg.C, and a required amount of organic nickel gas is introduced and is thermally decomposed, thus forming a nickel compound film 14 on the substrate surface. Then, the organic nickel is completely eliminated from the chamber, the heater is set to heat the substrate at 550 deg.C, and this condition remains for some time for performing solid growth, thus obtaining a crystallized silicon film 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a crystalline silicon semiconductor film such as a polycrystalline silicon film, a single crystal silicon film or a microcrystalline silicon film. The crystalline silicon film produced by using the present invention is used for various semiconductor devices.

[0002]

2. Description of the Related Art A thin film transistor (hereinafter referred to as TFT) using a thin film semiconductor is known. This is configured by forming a thin film semiconductor, particularly a silicon semiconductor film, on a substrate and using this thin film semiconductor. Although TFTs are used in various integrated circuits, they are attracting attention especially as a switching element provided in each pixel of an active matrix type liquid crystal display device and a driver element formed in a peripheral circuit portion.

Although it is easy to use an amorphous silicon film as a silicon film used for a TFT, its electrical characteristics are far lower than those of a single crystal semiconductor used in a semiconductor integrated circuit. There's a problem. Therefore, it has been used only for a limited purpose such as a switching element of an active matrix circuit. To improve the characteristics of the TFT, a crystalline silicon thin film may be used. In addition to single crystal silicon, a crystalline silicon film is called polycrystalline silicon, polysilicon, microcrystalline silicon, or the like.
In order to obtain a silicon film having such crystallinity, first, an amorphous silicon film is formed and then heated (thermal annealing).
It may be crystallized by. This method is called a solid phase growth method because the amorphous state changes to the crystalline state while maintaining the solid state.

However, in the solid phase growth of silicon, the heating temperature must be 600 ° C. or higher and the time must be 10 hours or longer, which makes it difficult to use an inexpensive 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 considering the enlargement of the substrate area, there is a problem in performing thermal annealing at 600 ° C. or higher. In order to solve such a problem, 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 the 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 (catalyst element that promotes crystallization), a film of the catalyst element or its compound may be deposited by sputtering. 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. When the film is formed by sputtering,
It is difficult to control the amount, that is, the thickness,
Moreover, it was more difficult to obtain a uniform thickness within the substrate. Therefore, the characteristics of the obtained semiconductor device are varied.

Further, in the film formation by sputtering, the amorphous silicon film is greatly damaged by the impact of sputtering, so that the characteristics of the obtained semiconductor device are not always satisfactory. There is also a method of forming a film by means such as spin coating instead of sputtering. However, it was difficult to obtain a uniform film by the spin coating method. For example, in the case of a rectangular substrate such as a liquid crystal display, the solution is likely to collect at the four ends, and the film thickness is not uniform. Further, when the solvent is dried to form a film of the catalytic element compound, the film thickness becomes non-uniform due to non-uniformity of drying and generation of crystal nuclei, which is a cause of variations in semiconductor devices.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a thin film silicon semiconductor having crystallinity by heat treatment at a temperature lower than that required for a normal solid phase growth method using a catalytic element. Enables control of trace amounts of catalytic elements. (2) It is possible to uniformly introduce the catalyst element. The purpose is to meet such requirements. Further, (3) it is also intended to improve productivity when introducing the catalyst element.

[0008]

In order to achieve the above object, the present invention provides amorphous silicon by applying energy such as heat or light to vapor or gas of an organic metal having a catalytic element to decompose it. It is characterized in that a film of a catalytic element or its compound is deposited on the film surface. The above configuration has the following basic significance. (A) The concentration of the catalyst element in the atmosphere can be strictly controlled by the vapor pressure or the like, and if introduction into the atmosphere is stopped, it will not be deposited on the amorphous silicon film any more. (B) In the process of decomposition and deposition by applying energy from the outside, a very uniform film is formed on the surface and no damage is given to the amorphous silicon film. (C) After the step of depositing the coating film of the catalytic element or its compound by decomposition by applying energy from the outside, if the heat treatment is continued, solid phase growth is continuously performed. Therefore, it can contribute to the improvement of productivity.

In the present invention, when nickel is used as a catalyst element, biscyclopentadienyl nickel (Bis (cyclopemetadienyl) nic) is used.
kel, Ni (C ₅ H ₅ ) ₂ , below, BCP nickel,
Or it is called BCP salt) or bismethylcyclopentadienyl nickel (Bis (methylcyclope
ntadienyl) nickel, Ni (CH ₃ C ₅
H _{4) 2,} or less, BMCP nickel or BMCP
Salt), bis-2,2,6,6-tetramethyl-
3,5-Heptanediononickel (Bis- (2,2,
6,6-Tetramethyl-3,5-hptan
ediono) nickel, Ni (C ₁₁ H ₁₉ O ₂ ).
₂ ) should be used.

In the case of BCP nickel, the melting point is 173-
174 ° C., and vapor pressures at 90 ° C. and 130 ° C. are 0.04 torr and 0.6 torr, respectively. B
In the case of MCP nickel, the melting point is 34 ° C and 90
Vapor pressures at ℃ and 130 ℃ are 1.6 torr, respectively
r, 15 torr. The film obtained by decomposing these organic metals may be directly deposited on the amorphous silicon film in the region where the catalytic element is to be introduced, or a thin oxide film of 100 Å or less is first formed and then formed on it. May be done.

Further, by selectively depositing a film of a catalytic element or its compound, crystal growth can be selectively performed. For example, a mask film is selectively formed so that the surface of the amorphous silicon film is substantially exposed only in a specific portion. The required thickness of the mask film depends on the material of the mask film, but in the case of silicon oxide, 500 Å or more is sufficient. Then, by depositing a film having a catalytic element according to the present invention, the catalytic element is introduced only in a specific portion of the amorphous silicon film. In this case, crystal growth can be performed in the direction parallel to the surface of the silicon film from the region where the coating is deposited toward the region where the coating of the catalytic element or its compound is not introduced. In this specification, a region in which crystal growth is performed in a direction 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 catalytic 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. However, in order to deposit such a coating having a selective catalytic element, a photolithography step must be performed before the deposition, and a heating step is present before the subsequent photolithography step. There is a possibility that such obstacles will occur. Therefore, such a problem must be taken into consideration in selecting lateral crystal growth.

The present invention is usually carried out by the following steps. That is, the substrate is placed in the chamber and the substrate is heated to a predetermined temperature. An organometallic vapor or gas having a catalytic element that promotes crystallization of the amorphous silicon film is introduced into the chamber. Heat, light, or plasma is caused to act on the introduced vapor or gas to decompose it, and a coating film of a catalytic element or its compound is deposited on the surface of the substrate. The amorphous silicon film is crystallized by heat treatment. Is. Of these, in the step of 1, the vapor or gas of the organic metal is not continuously flowed,
Only a fixed amount (for example, 1 sccm) may be introduced into the chamber. The atmosphere at that time may be reduced pressure or atmospheric pressure. LP when performing under reduced pressure
An apparatus having a configuration such as CVD may be used, and in the case of atmospheric pressure, an apparatus such as APCVD (normal pressure CVD) can be used. It is useful to react the catalyst element deposited during or after this step with the amorphous silicon at the interface to form a reaction product. By forming the product in advance, crystallization in the subsequent thermal crystallization step can be performed more easily.
The reason for this is not clear, but it is speculated that these products acted as crystal nuclei. The step (1) may be carried out in the chamber after being taken out from the chamber and then carried out in another thermal annealing apparatus.

If strong light such as a laser is irradiated after the step, it is possible to crystallize even a portion which is not completely crystallized by solid phase growth, and crystalline silicon having better characteristics can be obtained. it can. As for the laser to be used, various excimer lasers are easy to use. Further, when the catalytic element is accumulated in the chamber for depositing the coating film of the catalytic element or its compound, the catalytic element is excessively introduced into the silicon film, and therefore it is desirable to frequently clean the chamber. . Alternatively, cleaning may be performed with plasma or the like each time it is used.

In the present invention, the most remarkable effect can be obtained when nickel is used as the catalyst element, but as other types of catalyst element that can be used, Pd, Pt, Cu, Ag, Au, and In, Sn, P,
As and Sb can be used. Further, one or more kinds of elements selected from Group VIII elements, IIIb, IVb, and Vb elements can also be used.

[0016]

【Example】

[Embodiment 1] This embodiment shows an example of forming a crystalline silicon film on a glass substrate. A process of introducing a catalytic element (here, nickel is used) and crystallization will be described with reference to FIG. In this example, Corning 7059 glass was used as the substrate. The size is 100 mm × 100 mm.

First, the silicon oxide film 12 was formed on the substrate 11 by the sputtering method or the plasma CVD method. The thickness of the silicon oxide film 12 is 1000 to 5000Å, for example,
It was set to 2000Å. (FIG. 1A) Next, the amorphous silicon film 13 is formed by plasma CVD or LPCV.
Amorphous silicon film 100 to 1 by D method
Form 500Å. Here, the amorphous silicon film 13 was formed to a thickness of 500 Å by the plasma CVD method. (Fig. 1 (B))

Then, a hydrofluoric acid treatment was performed to remove the dirt and the natural oxide film, and the substrate was placed in the chamber 101 shown in FIG. 1 (E). Here, the chamber 101
Will be briefly described. A tube for introducing gas and a tube for exhausting gas from the outside are connected to the chamber 101, and the former has two systems. The first is a system for introducing organic nickel gas / vapor, and the second is a carrier gas thereof. In the first system, organic nickel gas / vapor generated from the vaporizer (for example, BMCP nickel)
Are carried by a suitable gas (eg, argon or hydrogen). In this case, the pipe must be kept at a suitable temperature, preferably at the same temperature as the vaporizer or higher so that the organic nickel does not condense in the pipe.

From the first gas system, organic nickel gas
Although vapor is obtained, it is difficult to control its concentration to the required amount. That is, the vapor pressure is determined by the temperature of the vaporizer, and the concentration significantly fluctuates due to a slight difference in temperature. Therefore, a carrier gas (for example, argon or hydrogen) is introduced from the second gas system to dilute the organic nickel gas / vapor.
The concentration ratio is controlled by valves V1 and V2. In this way, the organic nickel gas or vapor is introduced into the chamber 101. Parallel plate electrodes 106 and 107 are provided in the chamber, and an RF power source 105 is provided outside the chamber. This is for generating plasma between the electrodes to clean nickel remaining in the chamber.

A heater 104 and a susceptor 102 are provided in the chamber, and a sample 103 is placed thereon. Of course, it is desirable that the entire chamber be maintained at a temperature at which organic nickel does not condense. The substrate needs to be heated to a temperature higher than that temperature and maintained at a temperature at which the organic nickel is thermally decomposed. A method for depositing a nickel film using the chamber of this configuration will be described. First, the substrate is set. Then, V3 is opened while V1 and V2 are closed, and the inside of the chamber is evacuated to an appropriate pressure. Since this process does not require such a high vacuum,
Exhaust of 1 to 500 mTorr is sufficient. Next, the heater 104 is energized to heat the substrate to 500 to 550 ° C.

In this state, V3 is closed, V1 and V2 are opened, and organic nickel gas is introduced. When the required amount of organic nickel gas is introduced, V1 and V2 are closed. As a result, the organic nickel gas and the carrier gas are confined in the chamber, the organic nickel gas is thermally decomposed on the substrate, and the nickel compound film 14 is formed on the substrate surface.
Is formed. (FIG. 1 (C)) After that, the process proceeds to the solid-phase growth process, in which case the following two methods can be considered. The first method is to take out the substrate to the outside and move to the solid phase growth step.
In that case, turn off the heater 104, cool the substrate,
Further, V2 and V3 are opened to completely replace the gas in the chamber with a gas harmless to the human body. And
V3 is closed, the chamber is opened to the atmosphere, and the substrate is taken out. The subsequent solid phase growth process is the same as the conventional case. After taking out the substrate, the chamber may be cleaned by setting the pressure in the chamber to an appropriate pressure and causing an electric discharge between the electrodes 106 and 107.

The second method is to perform solid phase growth by subsequently heating the substrate in the chamber. The procedure in that case is as follows. First, V2
And V3 are opened, and the organic nickel gas is completely removed from the chamber. This is because if the organic nickel gas remains in the chamber, nickel is continuously introduced even in the solid phase growth step, and the concentration of nickel in the silicon film becomes excessive. It is desirable to introduce an inert gas such as argon or nitrogen into the chamber.

The heater is set so as to heat the substrate to 500 to 580 ° C., for example 550 ° C., and the solid phase growth proceeds by leaving it in this state. Time required,
For example, after leaving it for 4 hours, V3 is closed, the heater is turned off, the substrate is cooled, and then taken out. Thus, the crystallized silicon film 15 could be obtained. The above heat treatment can be performed at a temperature of 450 ° C. or higher, but if the temperature is low, the heating time must be lengthened and the production efficiency will be reduced. Further, if the temperature is 580 ° C. or higher, the problem of heat resistance of the glass substrate used as the substrate is exposed. Thus, the thermal annealing temperature must be determined in consideration of productivity and heat resistance of the substrate. (Fig. 1
(D)) In this embodiment, the pressure in the decomposition and deposition steps of the organic nickel may be reduced pressure or atmospheric pressure. The reason is that the amount of nickel deposited is not determined by pressure, but by its partial pressure. For example, even at atmospheric pressure, by increasing the dilution rate with the carrier gas, the amount of nickel is reduced to the same level as when decompressing. It is possible to do so. Further, in the case of atmospheric pressure, by adopting a structure in which deposition is performed while spraying from a nozzle like APCVD,
It is possible to reduce the frequency of cleaning.

[Embodiment 2] In this embodiment, an apparatus similar to that of Embodiment 1 is used and an example in which organic nickel is decomposed by plasma instead of heat is shown. A process of introducing a catalytic element (here, nickel is used) and crystallization will be described with reference to FIG. Also in this example, Corning 7059 glass was used as the substrate. The size is 1
The size is 00 mm × 100 mm.

An amorphous silicon film 13 is formed on the substrate 11,
Since the process is the same as in Example 1 until the chamber 101 is introduced after the natural oxide film is removed, the description thereof is omitted. Chamber 10
After placing the substrate 11 in the substrate 1, organic nickel gas is introduced by the same operation as in the first embodiment. In this embodiment, since the purpose is to decompose the organic nickel by using plasma, the pressure inside the chamber needs to be reduced. The pressure is appropriately about 1 to 1000 Pa, but in this embodiment, it was adjusted to 20 Pa. As described above, the parallel plate type electrodes 106 and 107 are provided in the chamber, and the RF power source 105 is provided outside the chamber. This was due to chamber cleaning in Example 1, but
This time, we will use it for the decomposition of organic nickel.

The structure in which the heater 104 and the susceptor 102 are provided in the chamber and the sample 103 is placed on the heater 104 and the susceptor 102 is the same as in the first embodiment. Of course, it is desirable that the entire chamber be maintained at a temperature at which organic nickel does not condense. Then, in this example, the substrate was also kept at the same temperature as in the entire chamber, at a temperature at which organic nickel was not condensed. This is because only decomposition by plasma is used instead of thermal decomposition. A method for depositing a nickel film using the chamber of this configuration will be described. First, the substrate is set. Then, V3 is opened while V1 and V2 are closed, and the inside of the chamber is evacuated to an appropriate pressure. This step did not require such a high vacuum in Example 1, but
In this embodiment, it is desirable to draw a high vacuum to some extent.

In this state, V3 is closed, V1 and V2 are opened, and organic nickel gas is introduced. In this embodiment, the gas was always flown, and the pressure was adjusted to 20 Pa by adjusting the conductance of the exhaust system. Next, a high frequency RF region was applied between the electrodes to form plasma, and the organic nickel was decomposed and deposited on the substrate. The high frequency output was 20 W and the film formation time was 2 minutes.
(FIG. 1 (C)) After that, the process proceeds to the solid phase growth step. However, in this example, the substrate temperature and the substrate temperature required for thermal crystallization are significantly different. Not a good idea in terms of throughput. Therefore, the method of taking out the substrate to the outside and moving to the solid phase growth step will be adopted. In that case, the heater 104 is turned off, the substrate is cooled, and V2 and V3 are further opened to completely replace the gas in the chamber with a gas harmless to the human body.
Then, V3 is closed, the chamber is opened to the atmosphere, and the substrate is taken out. The subsequent solid phase growth process is the same as the conventional case. After taking out the substrate, the chamber may be cleaned by setting the pressure in the chamber to an appropriate pressure and causing an electric discharge between the electrodes 106 and 107. However, more desirably, the chamber 101 is configured as a multi-chamber having a load chamber and an unload chamber, whereby further improvement in throughput can be expected. Silicon film 1 crystallized in this way
It was possible to obtain 5. The above heat treatment can be performed at a temperature of 450 ° C. or higher, but if the temperature is low, the heating time must be lengthened and the production efficiency will be reduced. Also, 5
When the temperature is 80 ° C. or higher, the problem of heat resistance of the glass substrate used as the substrate is exposed. Thus, the thermal annealing temperature must be determined in consideration of productivity and heat resistance of the substrate. (FIG. 1 (D)) [Embodiment 3] In this embodiment, after nickel is formed on the surface of amorphous silicon by the method shown in Embodiment 2, nickel silicide is continuously formed on the surface and then thermal crystallization is performed. An example in which Decomposes organic nickel by RF plasma,
The process up to the deposition is similar to that of the second embodiment, and therefore the description thereof is omitted.
After that, V3 is opened to expel the residual gas inside, the organic nickel is completely exhausted, and then only the carrier gas is introduced again by opening V2. And the pressure is about 1 to 1000P, which is about the same as when organic nickel is decomposed.
Although about a is desirable, the pressure is 25 Pa in this embodiment.
And Then, RF is applied between the electrode 106 and the electrode 107 in a state of only the carrier gas to form plasma, and the amorphous silicon film on which nickel is deposited is processed by the plasma to remove the nickel and the amorphous silicon. Nickel silicide is formed. This is due to the energy of accelerated ions or radicals. To make this work effectively, a bias is applied to the substrate to increase the acceleration, or a parallel plate type plasma is used for both electrodes. A method such as applying a DC bias between them is effective. Further, as the type of carrier gas introduced at this time, Ar or Xe is highly effective, and Xe is particularly desirable. It was found from an electron microscopic observation that the nucleation density was improved during thermal crystallization by forming the silicide by comparing the case where the silicide was formed by the above process with the case where the silicidation was not performed in Example 2.

[Embodiment 4] This embodiment shows an example in which organic nickel is decomposed and deposited by ultraviolet light to form a crystalline silicon film on a glass substrate. Using the chamber shown in FIG. 5, a catalytic element (nickel is used here)
Up to the step of introducing and crystallizing. In this embodiment, until the substrate is placed in the chamber,
Since it was performed in the same manner as in (1), it is omitted in this embodiment. Here, the chamber 201 will be briefly described. A tube for introducing gas and a tube for exhausting gas from the outside are connected to the chamber 201, and the former has two systems. The first is a system for introducing organic nickel gas / vapor, and the second is a carrier gas thereof. In the first system, the organic nickel gas / vapor (for example, BMCP nickel) generated from the vaporizer is carried by an appropriate gas (for example, argon or hydrogen). In this case, the pipe must be kept at a suitable temperature, preferably at the same temperature as the vaporizer or higher so that the organic nickel does not condense in the pipe. These structures are similar to those of FIG.

From the first gas system, organic nickel gas
Although vapor is obtained, it is difficult to control its concentration to the required amount. That is, the vapor pressure is determined by the temperature of the vaporizer, and the concentration significantly fluctuates due to a slight difference in temperature. Therefore, a carrier gas (for example, argon or hydrogen) is introduced from the second gas system to dilute the organic nickel gas / vapor.
The concentration ratio is controlled by valves V11 and V12. In this way, the organic nickel gas or vapor is introduced into the chaber 201. A low-pressure mercury lamp 202 is installed above the chamber with a quartz window 203 interposed therebetween.

A heater 204 and a susceptor 205 are provided in the chamber, and a sample 206 is placed thereon. Of course, it is desirable that the entire chamber be maintained at a temperature at which organic nickel does not condense. The substrate is then heated to control the reaction between the deposited nickel and the amorphous silicon on the surface. For example, if it is not desired to react the two, it is possible to keep the substrate temperature at room temperature or lower. This is a possible configuration due to photoreaction where ionic damage and heating are not essential requirements. A method for depositing a nickel film using the chamber of this configuration will be described. First, the substrate is set. And V11, V12
With V closed, V13 is opened and the inside of the chamber is evacuated to an appropriate pressure.

In this state, V13 is closed, and V11 and V
Open 12 and introduce organic nickel gas. And
If the required amount of organic nickel gas is introduced, V11
And close V12. As a result, the organic nickel gas and the carrier gas are confined in the chamber, and then the low pressure mercury lamp 202 is energized to deposit a thin film obtained by decomposing the organic nickel on the substrate. In general, photo CVD is disadvantageous in that it has a low deposit, but in the present invention, it was necessary to control the deposition amount of a trace amount of metal, which was rather convenient. (FIG. 1C) After that, the substrate was taken out and a solid phase growth process was performed. This example has less interface damage than Examples 1 to 3,
It was possible to obtain a high quality crystalline silicon thin film.

[Embodiment 5] In this embodiment, in the manufacturing method shown in Embodiment 1, a 1200 Å silicon oxide film is selectively provided, and nickel is selectively introduced by using this silicon oxide film as a mask to form a solid phase. This is an example of performing lateral crystallization by performing growth. FIG. 2 shows an outline of the manufacturing process in this example. First, the glass substrate (Corning 7
A silicon oxide film 22 having a thickness of 1000 to 5000 Å was formed on the (059, 10 cm square) 21. Furthermore, plasma C
The amorphous silicon film 2 is formed by the VD method or the low pressure CVD method.
3 was formed to a thickness of 500 to 1000Å. Further, a silicon oxide film 24 serving as a mask film was formed to a thickness of 1000 Å or more, here 1200 Å by a sputtering method. Regarding the thickness of the silicon oxide film 24, it has been confirmed by experiments by the inventors that there is no problem even if it is 500 Å.
In order to prevent nickel from being introduced into unintended locations due to the presence of pinholes, etc., a further allowance is provided here. (Fig. 2 (A))

Then, the silicon oxide film 24 was patterned into a required pattern by a usual photolithographic patterning process to form a window 25 for introducing nickel. The substrate thus processed was placed in the chamber 101 in the same manner as in Example 1, and using organic nickel gas,
A nickel compound film 26 having an appropriate thickness was deposited on the surface. (Fig. 2 (B))

Then, the amorphous silicon film 23 was crystallized by performing a heat treatment at 550 ° C. (nitrogen atmosphere) for 8 hours. At this time, first, crystallization started in the region of the portion 27 where the nickel compound film was in close contact with the amorphous silicon film. (FIG. 2 (C)) After that, crystallization proceeded to the periphery as shown by the arrow in the figure, and the region 28 covered with the mask film 24 was also crystallized. (Fig. 2 (D))

In this way, the amorphous silicon film was crystallized. As shown in FIG. 2E, when crystallization is performed in the lateral direction as in this embodiment, three regions having different properties can be obtained. The first is a region where the nickel compound film was in close contact with the amorphous silicon film.
In (E), the area is indicated by 27. This region crystallizes in the first stage of the thermal annealing process. This area is called a vertical growth area. In this region, the nickel concentration is relatively high and the directions of crystallization are not uniform, and as a result, the crystallinity of silicon is not so excellent, so the etching rate for hydrofluoric acid and other acids is relatively high.

The second is a region in which lateral crystallization is performed, which is indicated by 28 in FIG. 2 (E). This area is called a horizontal growth area. This region has a uniform crystallization direction and a relatively low nickel concentration, and is a preferable region for use in a device. The third is an amorphous region which has not been laterally crystallized.

[Embodiment 6] This embodiment shows an example of manufacturing a thin film transistor (TFT) using a crystalline silicon film manufactured by using the method of the present invention. FIG. 3 shows an outline of the manufacturing process of this embodiment. First, an underlying silicon oxide film 302 was formed to a thickness of 2000 Å on a glass substrate 301. The silicon oxide film 302 is provided to prevent diffusion of impurities from the glass substrate. Then, an amorphous silicon film was formed in a thickness of 500Å in the same manner as in Example 1. (Fig. 3
(A) Then, as in Example 1, a nickel compound film 304 was deposited on the surface of the amorphous silicon film by a thermal decomposition method of organic nickel vapor. (Fig. 3 (B))

After that, the amorphous silicon film 303 was crystallized by performing thermal annealing at 550 ° C. for 4 hours to form a crystalline silicon film 305. And to this KrF
Irradiation with excimer laser light (wavelength 248 nm) was performed to further improve crystallization. The energy density of the laser is preferably 300 to 350 mJ / cm ² . In this way, in addition to crystallization by solid phase growth, irradiation with laser light to further enhance crystallinity has been described in Example 5, but the portion where the nickel compound film and amorphous silicon are in close contact This is because the crystallinity is not good because the crystallization directions are not uniform. In particular, many amorphous residues were observed at the grain boundaries. Therefore, it is desired to completely crystallize such an amorphous component of the crystal grain boundary by performing laser irradiation.
(Fig. 3 (C))

Next, the crystallized silicon film was patterned to form island regions 306. This island area 30
6 constitutes an active layer of the TFT. And plasma CV
According to the D method, the thickness is 200 to 1500Å, here 100
A 0Å silicon oxide film 307 was deposited. This silicon oxide film also functions as a gate insulating film. (FIG. 3D) Care must be taken in forming the silicon oxide film 307. Here, TEOS is used as a raw material, and the substrate temperature is 1 with oxygen.
RF at 50-600 ° C, preferably 300-450 ° C
It was decomposed and deposited by the plasma CVD method. The pressure ratio of TEOS and oxygen is 1: 1 to 1: 3, and the pressure is 0.05 to 0.
The RF power was set to 5 torr and 100 to 250 W. Alternatively, TEOS is used as a raw material and ozone C
The substrate temperature is set to 35 by the VD method or the atmospheric pressure CVD method.
It was formed at 0 to 600 ° C, preferably 400 to 550 ° C. After film formation, 400 ~ in an atmosphere of oxygen or ozone
You may anneal at 600 degreeC for 30 to 60 minutes.

After that, a polycrystalline silicon film doped with phosphorus having a thickness of 2000Å to 1 μm was formed by the low pressure CVD method, and this was patterned to form a gate electrode 308. Then, by ion doping (also called plasma doping) in the island-shaped silicon film of the TFT,
Impurities (phosphorus) were implanted in a self-aligning manner using the gate electrode as a mask. Phosphine (PH
₃ ) was used. Dose amount is 1 × 10 ¹⁴ to 4 × 10 ¹⁵ c
m ^-2 . Thus, the N-type impurity (phosphorus) region 309,
310 was formed. (Fig. 3 (E))

After that, an interlayer insulator 311 is formed on the entire surface,
Plasma CVD with TEOS as raw material and oxygen
Method, low pressure CVD method with ozone, or atmospheric pressure CV
A silicon oxide film having a thickness of 3000 to 8000Å was formed by the D method. The substrate temperature is 250 to 450 ° C., for example 350.
℃ was made. After the film formation, in order to obtain the flatness of the surface, the silicon oxide film may be mechanically polished or flattened by an etch back method. And the interlayer insulator 311
Were etched to form contact holes in the source / drain of the TFT, and wirings / electrodes 312 and 313 made of chromium or titanium nitride were formed. Finally, 3 in hydrogen
Annealing is performed at 00 to 400 ° C. for 0.1 to 2 hours to complete hydrogenation of silicon. In this way, the TFT was completed. A large number of TFTs may be produced at the same time and arranged in a matrix to form an integrated circuit such as an active matrix type liquid crystal display device. (Fig. 3 (F))

[Embodiment 7] This embodiment relates to a process of manufacturing a TFT. FIG. 4 shows an outline of the manufacturing process of this example. First, the underlying silicon oxide film 402 is formed on the glass substrate 401.
2000 Å, and an amorphous silicon film 403 5 on it.
00Å and 1000Å the silicon oxide film 404 to be the mask film
Was formed into each film. Then, the window 404 was selectively opened in the mask film 404. (FIG. 4 (A)) Then, as in Example 1, a nickel compound film 406 was deposited by a pyrolysis method of organic nickel vapor. In this step, the nickel compound film 40 is formed in the region of the window 405.
6 adhered to the surface of the amorphous silicon. (FIG. 4B) After that, by performing thermal annealing at 550 ° C. for 8 hours, the amorphous silicon film 403 is laterally crystallized as indicated by an arrow in the figure, and the vertical growth region 408 and the lateral growth are obtained. A region 409 was formed. The region which was not crystallized in this step remained the amorphous region 410. (Fig. 4 (C))

In the lateral crystallization as in this embodiment, the crystallinity of the lateral growth region is good.
Since it is possible to manufacture a TFT, laser light irradiation was not performed in this example. However, when the laser light is irradiated, a TFT having better characteristics can be obtained. Next, the crystallized silicon film was patterned to form island-shaped regions 411. The island-shaped region 411 constitutes the active layer of the TFT. As you can see from the figure, this island region 41
1 includes a vertical growth region 408 and a horizontal growth region 40.
9, an amorphous region 410 is included. Then, in this embodiment, the channel region of the TFT is made to be the lateral growth region 409. This is because the channel region is an important part that influences the characteristics of the TFT.

After that, a silicon oxide film 412 was deposited. This silicon oxide film also functions as a gate insulating film. Subsequently, an aluminum film having a thickness of 2000Å to 1 μm was formed by a sputtering method, and this was patterned to form a gate electrode 413. The aluminum may be doped with scandium (Sc) in an amount of 0.15 to 0.2% by weight. Then, the substrate was immersed in an ethylene glycol solution of tartaric acid having a pH of about 7 and 1 to 3%, and anodization was performed using platinum as a cathode and this aluminum gate electrode as an anode. The anodization was completed by first raising the voltage to 220 V with a constant current and then maintaining that state for 1 hour. In the present embodiment, in the constant current state, it is appropriate that the voltage rising rate is 2 to 5 V / min. As a result, the thickness 1500-3500Å,
For example, 2000 Å anodic oxide 414 is used as the gate electrode 4
13 was formed on the top and side surfaces. (Fig. 4 (D))

After that, an impurity (phosphorus) was self-alignedly injected into the island-shaped silicon film of each TFT by an ion doping method (also referred to as a plasma doping method) using the gate electrode portion as a mask. Phosphine (PH ₃ ) was used as the doping gas. The dose amount is 1 × 10 ¹⁴ ~
It was set to 4 × 10 ¹⁵ cm ⁻² . In this doping process, since the anodic oxide 414 exists, the impurity region 41
5, 416 and the gate electrode do not overlap and are separated,
It is a so-called offset state.

Thereafter, a KrF excimer laser (wavelength 248 nm, pulse width 20 nsec) was irradiated to improve the crystallinity of the portion where the crystallinity was deteriorated by the introduction of the impurity region. Laser energy density is 150 ~
400 mJ / cm ² , preferably 200-250 mJ /
It was cm ² . Thus, the N-type impurity (phosphorus) region 41
5, 416 were formed. The sheet resistance in these areas is 2
It was 00 to 800 Ω / □. By this laser irradiation step, the amorphous region 41 of the island-shaped silicon region 411 is
0 was also crystallized. (FIG. 4 (E)) In this process, instead of using a laser, a flash lamp is used, and the temperature is 1000 to 1200 ° C. in a short time.
So-called RTA (Rapid Thermal Annealing) (RTP, also referred to as rapid thermal process) of raising the temperature to (silicon monitor temperature) and heating the sample may be used.

After that, a silicon oxide film 417 having a thickness of 5 is formed on the entire surface.
000Å accumulated. Thereafter, the silicon oxide film 417 was etched with a buffered hydrofluoric acid solution to form contact holes in the source / drain of the TFT, and wiring / electrodes 418 and 419 of a multilayer film of titanium nitride and aluminum were formed.
In the contact hole etching process, the vertical growth region in the island-shaped silicon region has a higher etching rate than the horizontal growth region and the amorphous region, and therefore, the deep-etched region is etched as shown in the figure. Area 420
Occurred. As is clear from this, when the entire contact hole is included in the vertical growth region, there is a high risk of contact failure, so it is desirable to design the contact hole so that it also extends to regions other than the vertical growth region. Be done. In this way, the TFT was completed. (Fig. 4 (F))

[0048]

[Effect] As a method of introducing a catalytic element for promoting crystallization of an amorphous silicon film, a method of thermally decomposing vapor or gas of an organic compound of the catalytic element and depositing it on the amorphous silicon film is used.
As described above, the concentration of the catalyst element can be precisely controlled and the catalyst element can be added uniformly, and the uniformity of crystallinity can be improved. As a result, a highly reliable electronic device using a crystalline silicon film can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a process of Examples 1 to 4 and an outline of a chamber used in Examples 1 to 3.

FIG. 2 is a diagram showing a process of Example 5.

FIG. 3 is a diagram showing a TFT manufacturing process of Example 6;

FIG. 4 is a diagram showing a TFT manufacturing process of Example 7.

FIG. 5 is a diagram showing an outline of a chamber used in Example 4.

[Explanation of symbols]

 11 ... Glass substrate 12 ... Silicon oxide film 13 ... Amorphous silicon film 14 ... Nickel compound film 15 ... Crystalline silicon film 101 ... Chamber 102 ... -Susceptor 103 ... Sample substrate 104 ... Heater 105 ... RF power supply 106, 107 ... Parallel plate electrodes

Front page continued (72) Inventor Hisashi Otani 398 Hase, Atsugi City, Kanagawa Prefecture Semiconductor Energy Research Institute Co., Ltd.

Claims (9)

[Claims] 1. A first step of arranging a substrate having an amorphous silicon film in a chamber, and vapor or gas of an organic metal having a catalytic element for promoting crystallization of the amorphous silicon film in the chamber. Second to introduce
And a third step of thermally decomposing the vapor or gas to deposit a film of a catalytic element metal or its compound on the surface of the amorphous silicon film, and heat treating the amorphous silicon film. And a fourth step of crystallizing the crystalline semiconductor. 2. The method according to claim 1, after the fourth step,
A method for producing a crystalline semiconductor, comprising a step of irradiating a crystallized silicon film with a laser or strong light equivalent thereto. 3. The crystalline semiconductor manufacturing method according to claim 1, wherein an oxide film having a thickness of 100 Å or less is formed on the amorphous silicon film. 4. The mask film according to claim 1, wherein a mask film is formed on the amorphous silicon film, and the mask film is selectively etched so that the surface of the amorphous silicon film is selectively and substantially formed. A method for producing a crystalline semiconductor, characterized in that the crystalline semiconductor is exposed. 5. The method according to claim 1, wherein after the fourth step,
A method for manufacturing a crystalline semiconductor, which comprises removing a film covering a silicon film. 6. The N as the catalyst element according to claim 1.
i, Pd, Pt, Cu, Ag, Au, In, Sn, P,
A method for manufacturing a semiconductor, which comprises using one or more kinds of elements selected from As and Sb. 7. The method according to claim 1, wherein the catalyst element is VI
A method for manufacturing a semiconductor, which comprises using one or more kinds of elements selected from group II, group IIIb, group IVb, and group Vb. 8. The method for manufacturing a semiconductor according to claim 1, wherein the fourth step is performed in the chamber. 9. A first step of placing a substrate having an amorphous silicon film in a chamber and heating the sample, and an organic material having a catalytic element for promoting crystallization of the amorphous silicon film in the chamber. Second to introduce metal vapor or gas
And a third step of thermally decomposing the vapor or gas to deposit a coating film of the catalytic element metal or its compound on the surface of the amorphous silicon film, and after cooling the sample, in the chamber. A fourth step of cleaning the chamber by performing discharge, the method for producing a crystalline semiconductor, comprising: