JPH0950960A - Manufacture of crystalline semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thin film crystalline silicon semiconductor by a method wherein energy such as heat, light, etc., is applied to vapor or gas of organic metal having catalyst element to decompose it and a film of the catalyst element or its compound is deposited on the surface of an amorphous silicon film. SOLUTION: First, a silicon oxide film 12 is formed on a substrate 11. Then, an amorphous silicon film 13 is formed by a plasma CVD method. Organic nickel gas or vapor is introduced into a chamber and the substrate 11 is placed above a heater in the chamber and heated. Then organic metal containing catalyst metal element is introduced and is adsorbed by the surface of the amorphous silicon film 13 to form an organic nickel adsorption layer 14. A laser beam is applied to the surface of the amorphous silicon film 13 by which organic metal molecules containing catalyst metal element are adsorbed synchronously with the application to the organic metal gas to make a single atomic Ni layer adsorbed and a nickel compound film 15 is formed on the substrate surface. After that, the substrate 11 is transferred to a solid phase growth process to form a crystalline silicon film 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a crystalline silicon semiconductor film, for example, a polycrystalline silicon film, a monocrystalline silicon film, and a microcrystalline silicon film. The crystalline silicon film manufactured by using the present invention is used for various semiconductor devices.

[0002]

2. Description of the Related Art Thin film transistors (hereinafter referred to as TFTs) using thin film semiconductors are known. This is one in which a thin film semiconductor, particularly a silicon semiconductor film, is formed on a substrate, and is configured using this thin film semiconductor. The TFT is used in various integrated circuits, and is particularly noted 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.

It is convenient to use an amorphous silicon film as a silicon film used for a TFT, but its electrical characteristics are much lower than those of a single crystal semiconductor used for a semiconductor integrated circuit. There's a problem. Therefore, they have been used only for limited applications such as switching elements of active matrix circuits. In order to improve the characteristics of the TFT, a silicon thin film having crystallinity may be used. A silicon film having crystallinity other than single crystal silicon 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).
May be crystallized. This method is called a solid phase growth method because an amorphous state changes to a crystalline state while maintaining a solid state.

However, in the solid phase growth of silicon, a heating temperature of 600 ° C. or more and a time of 10 hours or more are required, and there is a problem that it is difficult to use an inexpensive glass substrate as the substrate. For example, Corning 7059 glass used for an active type liquid crystal display device has a glass strain point of 593 ° C., and there is a problem in performing thermal annealing at 600 ° C. or more in consideration of increasing the area of a substrate.

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. It has been found that crystallization can be performed at 550 ° C. for about 4 hours.

In order to introduce such a trace amount of element (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 such elements in a semiconductor impairs the reliability and electrical stability of a device using such a semiconductor, and is not preferable. When a film is formed by sputtering,
It is difficult to precisely control the amount, that is, the thickness,
Further, it was more difficult to obtain a uniform thickness in the substrate. For this reason, the characteristics of the obtained semiconductor device varied.

[0007] In the film formation by sputtering, since the amorphous silicon film is greatly damaged by the impact of sputtering, 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 coating by the spin coating method. For example, in the case of a rectangular substrate such as a liquid crystal display, the solution tends to collect at the four ends, and the film thickness is not uniform. Further, when the solvent is dried to form a coating film of the catalytic element compound, the thickness of the film becomes non-uniform due to non-uniformity of drying and generation of crystal nuclei,
It was a cause of variations in semiconductor devices.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a thin film silicon semiconductor having crystallinity by heat treatment at a temperature lower than a temperature required for a normal solid phase growth method using a catalytic element. Enables control of a very small amount of catalytic elements. (2) The catalyst element can be introduced uniformly. It is intended to satisfy such requirements. Further, (3) it is also intended to improve productivity when introducing the catalyst element.

[0010]

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. Also, in the above deposition process, it is difficult to control the film thickness by Å order by simply depositing it. Therefore, the adsorption process and the decomposition process are performed by using monoatomic layer adsorption in order. It is a feature.

The above configuration has the following basic significance. (A) The concentration of the catalytic element in the amorphous silicon film is uniquely determined by the ratio of the thickness of the atomic layer deposited on the surface to the thickness of the amorphous silicon film, and is controlled extremely uniformly over the entire substrate. It becomes possible to do. Further, by using a raw material having a large side chain such that the adsorbed species has a steric hindrance, the deposition rate can be reduced, and the addition of trace elements can be controlled even in the same atomic layer adsorption process. (B) In the adsorption process on the surface and the decomposition process 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 improvement in productivity.

In the present invention, when nickel is used as the catalytic element, biscyclopentadienyl nickel (Bis (cyclopemetadienyl) nic) is used.
_{kel, Ni (C 5 H 5} ) 2, hereinafter, BCP nickel,
Or BCP salt) or bismethylcyclopentadienyl nickel (Bis (methylcyclope)
ntadienyl) nickel, Ni (CH ₃ C ₅₎
H ₄ ) ₂ , hereinafter referred to as 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 ) etc. may be used.

In the case of BCP nickel, the melting point is 173-
174 ° C., and the 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.
The vapor pressure at 130 ° C. and 130 ° C. is 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, but the surface of the amorphous silicon film is very active. Therefore, there is a problem that it is easily oxidized, and as a result, uneven adsorption is likely to occur in the surface state. In that case, conversely, a thin oxide film having a thickness of 100 Å or less may be first formed on the surface of the amorphous silicon film and deposited on it.

Further, by selectively depositing a film of the 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 at a specific portion. The thickness required for the mask film varies depending on the material of the mask film, but in the case of silicon oxide, 500 ° or more is sufficient. Then, the catalyst element is introduced into only a specific portion of the amorphous silicon film by depositing a film having the catalyst element according to the present invention. In addition, even without using a mask in this way, the decomposition and deposition of only the region irradiated with light after adsorption of the monoatomic layer is promoted,
It is possible to introduce the catalytic element only to the region irradiated with light by using a technique such as re-desorbing the adsorbed species in the other region or washing out in the subsequent washing step.

In this case, crystal growth can be performed in a 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 where crystal growth is performed in a direction parallel to the surface of the silicon film is referred to as a region where crystal growth is performed in a lateral direction.

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. It is useful to use a crystalline silicon film as the active layer region of the semiconductor device, but it is generally preferable that the concentration of the catalytic element in the active layer region is low. Therefore, it is useful in device fabrication to form an active layer region of a semiconductor device using the region where the crystal growth has been performed in the lateral direction. However, in the conventional method of adding a catalytic element, a photolithography step must be performed before the deposition of a film having such a selective catalytic element, which is a disadvantage. was there. However, the use of light-assisted monoatomic layer adsorption (details will be described later) according to the present invention makes it possible to form a coating film containing a catalytic metal only in a region irradiated with light. It is possible to simplify. However, since there is a heating crystallization step before the subsequent photolithography step (generally island formation),
Problems such as contraction of the substrate may 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, a substrate is placed in a 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 and adsorbed on the surface of the amorphous silicon film. The organic metal having a catalytic element or a partially decomposed product thereof adsorbed on the surface of the amorphous silicon film is decomposed by applying heat or light to deposit a film of the catalytic element or its compound on the surface of the substrate. The amorphous silicon film is crystallized by heat treatment. It is.

In the above steps, the vapor or gas of the organic metal may be introduced into the chamber in a fixed amount (for example, 1 sccm) instead of being continuously flowed. This is basically determined by the temperature and the source gas. That is, the flow rate is taken on the horizontal axis,
When the adsorption amount is plotted on the vertical axis, it means that the adsorption amount corresponds to a monoatomic layer and a plateau region is used regardless of the flow rate. Although this area is generally called an ALE window, conditions are set so that this area is as wide as possible. When the ALE window can be widened by simply adjusting the temperature, the above steps can be realized without using light or the like. However, depending on the raw material, there is a case where there is almost no ALE window only by controlling the temperature. At this time, light is irradiated or the flow velocity of the raw material gas is extremely increased to create a situation in which the substrate surface cannot adsorb more than a monoatomic layer. It is necessary to devise.

The atmosphere in the adsorption and decomposition steps may be reduced pressure or atmospheric pressure. When the process is performed under reduced pressure, an apparatus having a structure such as LPCVD may be used, and when the atmospheric pressure is used, a device such as APCVD (normal pressure CVD) can be used. However, these are also determined by the temperature and the raw material, and it means that it is sufficient to use a region in which adsorption and re-desorption are just balanced and an ALE window can be wide. However, it is generally not desirable to use a decompression device from the viewpoint of throughput and cost, and it is desirable to devise the raw material and temperature so that the ALE window can be wide in the region close to atmospheric pressure.

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 presumed that those 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.

By irradiating strong light such as a laser after the above step, it is possible to crystallize even a portion that has not been completely crystallized by solid phase growth, and it is possible to obtain crystalline silicon having better characteristics. it can. Regarding the laser to be used, various excimer lasers are easily used.

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

[0025]

【Example】

[Embodiment 1] In this embodiment, an example is shown in which a crystalline silicon film is formed on the front surface of a glass substrate. The steps up to the step of introducing a catalyst element (in this case, using nickel) 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.

Next, the amorphous silicon film 13 is subjected to plasma CVD.
An amorphous silicon film is formed at a temperature of 100 to 1500 ° by a CVD method or an LPCVD method. Here, the plasma C
An amorphous silicon film 13 was formed to a thickness of 500 ° by the VD method. (Fig. 1 (A))

Then, hydrofluoric acid treatment was carried out to remove dirt and a natural oxide film, and the substrate was placed in the chamber 201 shown in FIG. 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, hydrogen). At this time, the pipe must be kept at an appropriate temperature, preferably 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 steam 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 fluctuates significantly due to a slight difference in the temperature. Therefore, a carrier gas (for example, hydrogen) is introduced from the second gas system to dilute the organic nickel gas / vapor. This dilution is also used to control the flow rate.

In this way, the organic nickel gas or vapor is introduced into the chamber 201. A heater 204 is provided in the chamber, and the substrate is placed thereon. The substrate is then heated to a temperature that maximizes the ALE window depending on the material. This temperature is generally about 300 ° C to 500 ° C, and this time is 350 ° C.
Heated to ℃.

Of course, it is desirable to keep the temperature of the entire chamber at a level at which organic nickel does not condense.

A method of depositing a nickel film using the chamber of this structure will be described. First, the substrate is set. Then, the inside of the chamber is evacuated to an appropriate pressure. This process does not require a high vacuum, so 1 to 500
Exhaust of mTorr is also sufficient. Next, the heater 204
To heat the substrate to 350 ° C.

In this state, open V12 and let hydrogen gas flow,
The inside of the chamber is brought to a predetermined pressure. Hydrogen flow rate is 3 SLM
The reaction pressure was 1 × 10 ⁴ Pa this time. Next, after confirming that a steady state is achieved at a predetermined pressure and temperature, an organic metal containing a catalytic metal element is introduced. This time, BMCP nickel is used and the flow rate is 100sc
cm, and V11 is opened at the same time as hydrogen as a carrier gas for 1 second to irradiate the surface and cause it to be adsorbed on the surface of the amorphous silicon film. (Fig. 1 (B))

Then, in synchronization with the irradiation of the organic metal gas, the light source 202 irradiates the surface of the amorphous silicon film on which the organic metal molecules containing the catalytic metal element are adsorbed. This light source may be a laser light or the like, or another light source such as a xenon lamp, a halogen lamp, a low pressure or high pressure mercury lamp, or the like. This only assists the decomposition of the organic metal on the surface of the amorphous silicon film, and therefore light of such a high intensity is not necessary. The significance of this light irradiation will be described with reference to FIG.

When the surface of the amorphous silicon film is irradiated with the organonickel metal gas, at that moment, there are a portion 501 where the gas is not adsorbed, and a molecule 502 which is adsorbed in the polyatomic layer. Reference numeral 503 is an atomic group in which the organic portion is partially decomposed and chemically adsorbed on the surface of the amorphous silicon film. After that, when the organic nickel is no longer supplied, it is simply adsorbed by physical adsorption or van der Waals force.
And 504 and the like are desorbed, and complete monoatomic layer adsorption cannot be performed on the surface. When light irradiation is performed at the same time, the migration on the surface is accelerated by the light, and it is possible to increase the deposition rate (for example, like the molecule 502), and at the same time, it is only loosely bound to the surface. It is possible to perform photo-assisted decomposition on the molecule and then prevent the molecule from being desorbed. As a result, it becomes possible to form a substantially complete monoatomic layer.

As a light source, a xenon lamp is used this time,
A shutter 203 was used to synchronize with the irradiation of gas. Then, it was possible to adsorb almost a monoatomic layer of Ni every one sequence of the gas irradiation and the light irradiation.
Using almost the same conditions as above, the organic metal B
It has been found that when MCP nickel is used, the nickel layer formed by one sequence does not become a complete monatomic layer. It is considered that this is a result of the deposition rate being less than 1 due to the large steric hindrance. In this way, the nickel compound film 14 is formed on the surface of the substrate. (Figure 1
(D))

After that, a solid phase growth step is performed. The solid phase growth step may be performed in the same chamber as the chamber in which the nickel compound film is deposited. However, since the throughput generally decreases significantly (because it is a single wafer type), it is appropriate to take it out to the outside and use a diffusion furnace or the like. This time, another vertical furnace will be used. The heater 204 is turned off to cool the substrate, and then the gas in the chamber is completely replaced with a gas harmless to the human body. Then, 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.

The substrate is 500 to 650 ° C. during solid phase growth, for example, 55 when using a Corning 7059 substrate.
The solid phase growth proceeds by setting the temperature to 0 ° C. and leaving it in this state. When the Corning 1737 substrate is used as the substrate, the temperature can be further increased and crystallization at about 600 ° C. is possible. Even when the temperature is increased in this way, crystal growth is possible in a very short time compared to the case where the conventional catalyst metal is added (2
4 hours will be shortened to about 2 hours), so a sufficient advantage can be obtained. Thus, the crystallized silicon film 15 could be obtained. As described above, 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, when the temperature is about 650 ° 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 the productivity and the heat resistance of the substrate.
(Fig. 1 (E))

[Embodiment 2] This embodiment shows an example in which the same raw material as in Embodiment 1 is used, and light irradiation is selectively performed to add nickel only to the region irradiated with the light. FIG.
The process up to the step of crystallizing by introducing a catalytic element (here, nickel is used) will be described. Also in this example, Corning 1737 glass was used as the substrate.
The size is 100 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.

Next, a portion for selectively irradiating light will be described with reference to FIG. Substrate 1 in chamber 101
After installing No. 1, organic nickel gas is introduced by the same operation as in Example 1. Then, the surface of the substrate is irradiated with an argon laser 105 in synchronization with the introduction of the organic nickel gas.
For this irradiation, an argon laser is a CW laser.
Therefore, the shutter 106 is used for perfect synchronization. After that, only hydrogen was flowed for about 10 seconds, and then gas and light irradiation were performed again. 1 such sequence
By repeating the process about 0 times, it was possible to form a nickel layer having a thickness equal to (the thickness of the monoatomic layer) × (the number of sequences) exactly. This time, unlike Example 1, the reason why the film formation was repeated a plurality of times is to sufficiently perform lateral growth.
Further, in the portion not irradiated with light, the decomposition of the organic nickel on the surface hardly occurs, so most of the nickel is re-desorbed during the interval of about 10 seconds in which only hydrogen is flown. Substantially no nickel is added to the part.

The structure in which the heater 104 is provided in the chamber and the sample 107 is placed on the heater 104 is the same as in the first embodiment.
Of course, it is desired that the entire chamber be maintained at a temperature at which the organic nickel does not condense. In this embodiment, the temperature of the substrate was also maintained at the same level as that of the entire chamber し な い such that organic nickel did not condense. This is to prevent organic nickel that is thermally decomposed in the vapor phase from depositing on the substrate surface.

After that, the process proceeds to the solid phase growth step. However, in the present embodiment, the substrate temperature and the substrate temperature required for thermal crystallization are greatly different, and therefore, performing in the same chamber is from the viewpoint of throughput. Not a good idea. 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, the inside is purged with nitrogen, the chamber is opened to the atmosphere, and the substrate is taken out. The subsequent solid-phase growth process is almost the same as that of Example 1, but this time, the temperature is raised to 600 ° C. higher than that of Example 1 in order to carry out lateral growth (possible because the Corning 1737 substrate is used. And that time was 4 hours.

As a result, elliptical crystallization occurred only in the light-irradiated region, and a lateral growth region of about 100 μm was observed around the region. In addition, almost no crystallization was observed in the regions further apart, and it was confirmed that nickel could be selectively added.

[Embodiment 3] In this embodiment, nickel is formed on the surface of amorphous silicon by the method shown in Embodiment 1, nickel silicide is continuously formed on the surface, and then thermal crystallization is performed. Indicates.

The process until the organic nickel is decomposed and deposited by the xenon lamp is the same as that of the second embodiment, and the description thereof will be omitted.

After that, V13 is opened to expel the residual gas inside, the organic nickel is completely exhausted, and then nitrogen purge is performed. And with the nitrogen flushed,
The temperature of 204 is raised to about 450 ° C. or higher. Then, nickel silicide is formed from nickel and amorphous silicon adsorbed as a monoatomic layer.

Comparing the case where the silicide is formed by the above process with the case where the silicidation of Example 2 is not carried out, it is observed from the electron microscope observation that the formation of the silicide improves the nucleus generation density during the thermal crystallization. found.

[Embodiment 4] 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 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. 5 shows an outline of the manufacturing process in this embodiment. 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. (Figure 5 (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. 5 (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. 5 (C))

After that, the 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. 5 (D))

In this way, the amorphous silicon film was crystallized. As shown in FIG. 5E, when crystallization is performed in the lateral direction as in the present 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.
(E) is an area indicated by 27. This region crystallizes in the first stage of the thermal annealing process. This region is called a vertical growth region. In this region, the nickel concentration is relatively high, and the crystallization directions are not uniform. As a result, since the crystallinity of silicon is not so excellent, 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. 5 (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 that has not been crystallized in the lateral direction.

[Embodiment 5] This embodiment is an example in which the selective crystal growth method shown in Embodiment 2 is applied to Embodiment 4. The first major difference is that there is no need to form a mask made of a silicon oxide film. FIG. 6 shows an outline of the manufacturing process in this embodiment. First, a silicon oxide film 5 is formed on a glass substrate (Corning 7059, 10 cm square) 51.
2 was formed to a thickness of 1000 to 5000Å. Further, the amorphous silicon film 53 was formed to a thickness of 500 to 1000 Å by the plasma CVD method or the low pressure CVD method. (Figure 5 (A))

Then, the substrate was placed in a chamber having substantially the same structure as that used in Example 1, and according to Example 1, an organic metal 5 containing a catalytic metal element (nickel in this case) was used.
4 is adsorbed on the surface of the amorphous silicon film (slow adsorption without decomposition). (FIG. 6 (B)) Next, in synchronization with this, light irradiation is performed only on the region to which nickel is to be added. (FIG. 6
(C)) This is done as follows.

A window is provided above the substrate installed in the chamber, and a reticle having a predetermined pattern can be installed in the window. Then, a laser is irradiated from above this window and the reticle so that only the region without a mask on the reticle is irradiated with light. The laser is used here because the reticle and the substrate are farther apart than the normal patterning gap, so the pattern formed will be greatly blurred unless a coherent light source is used. Because. Of course, in order to improve the patterning accuracy, it is desirable to reduce the distance between the window, reticle and the substrate. However, since the substrate is in a heated state,
It is not possible to equalize this gap with a stepper, etc., so it can be said that this method is suitable for forming a relatively large pattern. As a result, it becomes possible to form the nickel film of the monoatomic layer or the compound film 55 thereof only in the region irradiated with the light. Of course, as in Example 2, it is important to repeat the above sequence a plurality of times to adjust the nickel addition amount. (FIG. 6 (D))

Then, the amorphous silicon film 53 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 56 where the nickel compound film was in close contact with the amorphous silicon film. (FIG. 6 (D))

After that, the crystallization proceeded to the periphery as shown by the arrow in the figure, and as a result, the crystallization by lateral growth was also performed in the region 57 where nickel was not deposited. (FIG. 6E)

In this way, the amorphous silicon film was crystallized. As shown in FIG. 6E, when crystallization is performed in the lateral direction as in the present embodiment, three regions having different properties can be obtained. The first is the region where the nickel compound film was in close contact with the amorphous silicon film.
In (E), the area is designated by 56. This region crystallizes in the first stage of the thermal annealing process. This region is called a vertical growth region. In this region, the nickel concentration is relatively high, and the crystallization directions are not uniform. As a result, since the crystallinity of silicon is not so excellent, 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 57 in FIG. 6 (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 the amorphous region 53 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. 7 shows an outline of the manufacturing process of this example. First, an underlying silicon oxide film 302 was formed to a thickness of 2000 ° on a glass substrate 301. This 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. 7
(A))

Then, in the same manner as in Example 1, a nickel compound film 304 was deposited on the surface of the amorphous silicon film by monoatomic layer deposition by decomposition of organic nickel vapor. (Fig. 7 (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 400 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 crystallization directions are not uniform, and the crystals obtained by the addition of nickel this time are needle-like crystals, so that a region that cannot be sufficiently crystallized only by solid phase growth is formed. In particular, many amorphous residues were observed at the crystal grain boundaries. Therefore, it is desired to completely crystallize such amorphous components at the crystal grain boundaries by performing laser irradiation. (Fig. 7
(C))

Next, the crystallized silicon film was patterned to form island regions 306. This island-shaped area 30
6 constitutes an active layer of the TFT. And plasma CV
According to the D method, the thickness is 200 to 1500 °, here 100
A 0 ° silicon oxide film 307 was deposited. This silicon oxide film also functions as a gate insulating film. (FIG. 7 (D))

Attention must be paid to the formation of the silicon oxide film 307. Here, TEOS is used as a raw material, and a substrate temperature is 150 to 600 ° C., preferably 300 to 45 ° C. together with oxygen.
Decomposition and deposition were performed at 0 ° C. by an RF plasma CVD method. TE
The pressure ratio between OS and oxygen is 1: 1 to 1: 3, the pressure is 0.05 to 0.5 torr, and the RF power is 100 to 25.
It was set to 0W. Alternatively, by using TEOS as a raw material together with ozone gas by a low pressure CVD method or a normal pressure CVD method,
The substrate temperature is set to 350 to 600 ° C, preferably 400 to 55.
Formed at 0 ° C. After film formation, annealing may be performed in an atmosphere of oxygen or ozone at 400 to 600 ° C. for 30 to 60 minutes.

After that, a phosphorus-doped polycrystalline silicon film 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. 7 (E))

After that, an interlayer insulator 311 is formed on the entire surface,
Plasma CVD of TEOS as raw material and oxygen
Method, reduced pressure CVD method with ozone, or normal pressure CV
A silicon oxide film was formed to a thickness of 3000 to 8000 ° by Method D. The substrate temperature is 250 to 450 ° C., for example, 350
° C. After film formation, in order to obtain surface flatness, the silicon oxide film may be mechanically polished or planarized 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, in hydrogen at 300 to 400 ° C.
Anneal for 1-2 hours to complete silicon hydrogenation. Thus, the TFT was completed. At the same time, a large number of TFTs may be manufactured and arranged in a matrix to form an integrated circuit such as an active matrix liquid crystal display device. (Figure 7 (F))

[Embodiment 7] This embodiment relates to a process of manufacturing a TFT. FIG. 8 shows an outline of the manufacturing process of this embodiment. First, the underlying silicon oxide film 402 is formed on the glass substrate 401.
2000 mm, and an amorphous silicon film 403
Each film was formed to a thickness of 00Å. And the mask film 4
A window 404 was selectively opened at 04. (FIG. 8A)

Then, a nickel compound film 406 is formed by selective monoatomic layer deposition of organic nickel vapor by the same method as in the fifth embodiment. In order to facilitate the adsorption, a thin oxide film layer was formed on the surface of the amorphous silicon film by ozone treatment (not shown). (Fig. 8 (B))

Thereafter, by performing thermal annealing at 550 ° C. for 8 hours, the amorphous silicon film 403 is crystallized in the lateral direction as shown by the arrow in the figure, and the vertical growth region 408 is formed.
And a horizontal growth region 409 was formed. The region that was not crystallized in this step remained as the amorphous region 410. (Fig. 8 (C))

In the lateral crystallization as in this embodiment, the crystallinity of the lateral growth region is good. Therefore, even if the crystallinity is not improved by irradiating laser light or the like after that as in Embodiment 6,
Since it is possible to manufacture a TFT, irradiation with laser light was not performed in this example. However, when a laser beam is irradiated, a TFT having better characteristics can be obtained.

Next, the crystallized silicon film was patterned to form island regions 411. This island-shaped area 41
Reference numeral 1 denotes an active layer of the TFT. As can be seen from the figure, the island region 411 includes a vertical growth region 408, a horizontal growth region 409, and an amorphous region 410.
In this embodiment, the channel region of the TFT is the horizontal growth region 409. This is because the channel region is an important part that affects 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 2000 to 1 μm was formed by a sputtering method, and this was patterned to form a gate electrode 413. Aluminum may be doped with scandium (Sc) by 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 anodic oxidation was performed using platinum as a cathode and the aluminum gate electrode as an anode. The anodic oxidation was first completed by increasing the voltage to 220 V at a constant current and maintaining the state for 1 hour. In this embodiment, in the constant current state, the voltage rising speed is suitably 2 to 5 V / min. As a result, the thickness is 1500-3500 °,
For example, the anodic oxide 414 of 2000 °
13 was formed on the top and side surfaces. (Figure 8 (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 called a plasma doping method) using the gate electrode portion as a mask. Phosphine (PH ₃ ) was used as a doping gas. The dose is from 1 × 10 ¹⁴ to
It was 4 × 10 ¹⁵ cm ⁻² . In this doping step, since the anodic oxide 414 exists, the impurity region 41 is formed.
5, 416 and the gate electrode do not overlap and are separated,
It is a so-called offset state.

Then, 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 to 250 mJ /
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-like silicon region 411 is formed.
0 was also crystallized. (FIG. 8 (E))

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, contact holes were formed 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 step, of the island-like silicon regions, the vertical growth region has a higher etching rate than the horizontal growth region or the amorphous region, and therefore, is etched deeply as shown in the figure. Area 420
Occurred. As is clear from this, if the entire contact hole is included in the vertical growth region, there is a high risk of contact failure. Therefore, it is desirable to design the contact hole so as to cover a region other than the vertical growth region. It is. Thus, the TFT was completed. (Figure 8 (F))

[0079]

[Effect] As a method of introducing a catalytic element that promotes crystallization of an amorphous silicon film, vapor or gas of an organic compound of the catalytic element is adsorbed and decomposed to form a single atomic layer on the amorphous silicon film. By the method of depositing, the concentration of the catalyst element can be precisely controlled, and moreover, 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 process diagram of monolayer adsorption according to the present invention.

FIG. 2 is an apparatus diagram used in the photo-assisted monoatomic layer adsorption step of the present invention.

FIG. 3 is an apparatus diagram used in the photo-assisted monoatomic layer adsorption step of the present invention.

FIG. 4 is a principle diagram of a photo-assisted monoatomic layer adsorption process of the present invention.

FIG. 5 is a process diagram of a crystal growth method using the present invention.

FIG. 6 is a process diagram of a crystal growth method using the present invention.

FIG. 7 is a process diagram when the present invention is applied to a TFT manufacturing process.

FIG. 8 is a process diagram when the present invention is applied to a TFT manufacturing process.

[Explanation of symbols]

 11 ... Glass substrate 12 Silicon oxide film 13 Amorphous silicon film 14 Organic nickel adsorption layer 15 Nickel or nickel compound layer 16 Crystal Silicon film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01L 29/786 H01L 29/78 627G 21/336

Claims (13)

[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. The second step of introducing and adsorbing onto the surface of the amorphous silicon film, and thermally decomposing the adsorbed molecules of the vapor or gas, the catalytic element metal or its compound A crystalline semiconductor manufacturing method comprising: a third step of depositing a film; and a fourth step of crystallizing the amorphous silicon film by heat treatment. 2. The method according to claim 1, wherein after the fourth step,
A method for manufacturing a crystalline semiconductor, comprising a step of irradiating a crystallized silicon film with a laser or an equivalent strong light. 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 semiconductor manufacturing method characterized by utilizing one or more elements selected from Group II, IIIb, IVb, and Vb elements. 8. A first step of disposing 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. A second step of introducing and adsorbing onto the surface of the amorphous silicon film, and by irradiating with light or a laser at the same time as or after the adsorption step to decompose molecules of the adsorbed vapor or gas. A crystal having a third step of depositing a film of a catalytic element metal or a compound thereof on the surface of the amorphous silicon film, and a fourth step of crystallizing the amorphous silicon film by heat treatment. For manufacturing a conductive semiconductor. 9. The decomposition process of a molecule consisting of an organometallic vapor or gas having a catalytic element adsorbed on the surface of an amorphous silicon film according to claim 8, wherein the decomposition of the molecule comprises an interaction between light and heat. A method for producing a crystalline semiconductor, comprising: 10. A first step of disposing 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. A second step of introducing and adsorbing on the surface of the amorphous silicon film, and at the same time as or after the adsorption step, light or a laser is selectively irradiated to select the molecule consisting of the adsorption vapor or gas. Third step of selectively depositing a film of the catalytic element metal or its compound on the surface of the amorphous silicon film by thermal decomposition, and crystallizing the amorphous silicon film by heat treatment A crystalline semiconductor manufacturing method including a fourth step. 11. The crystal growth during heat treatment according to claim 10, wherein the selective growth is performed in a lateral direction from a region where a coating of a catalytic element metal or its compound is deposited to a region where the coating is not deposited. A method for producing a crystalline semiconductor, wherein a region in which crystal growth has progressed and the laterally grown crystal is used as an active layer region. 12. A step of adsorbing the organic metal on the surface of the amorphous silicon film by using an organic metal vapor or gas having a catalytic element for promoting crystallization of the silicon film, simultaneously with or after the adsorbing step. A method for manufacturing a crystalline semiconductor, comprising: a step of decomposing the adsorbed organic metal to deposit a film containing the catalytic metal; and a step of crystallizing the amorphous silicon film by heat treatment. 13. A step of adsorbing an organic metal having a catalytic element that promotes crystallization of a silicon film on the surface of an amorphous silicon film, and at the same time as or after the adsorption step, the adsorbed organic metal is decomposed to obtain the A crystalline semiconductor manufacturing method comprising: a step of depositing a film containing a catalytic metal; and a step of crystallizing the amorphous silicon film by heat treatment.