JPH06244105A - Manufacture of semiconductor - Google Patents

Abstract

PURPOSE:To form a crystalline silicon film of low cost, by forming clusters or the like on a silicon film, annealing the film at a temperature lower than the crystallization temperature of ordinary crystal silicon, and performing annealing at a temperature in a specified range, in an atmosphere containing chlorine atoms like chlorine or chloride. CONSTITUTION:A substratum silicon oxide film 2 is formed on a substrate 1 by a plasma CVD method. A nickel film 3 is deposited to be 1000Angstrom thick or less by a sputtering method. An amorphous silicon film 4 is deposited to be 1500Angstrom thick by a plasma CVD method. Hydrogen outgasing is performed for 1-2 hours at 430 deg.C in a nitrogen atmosphere. After that, annealing is performed in an anealing furnace at 450 deg.C for 8 hours, in a nitrogen atmosphere. After crystallization is ended, the temperature is kept at 400-600 deg.C, and trichloroethylene (C2HCl3) which is diluted with hydrogen or oxygen to be 1-10% is introduced into the annealing furnace, and annealing is performed for 1 hour.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film insulating gate type field effect transistor (thin film transistor or TF).
The present invention relates to a method for obtaining a crystalline semiconductor used in a thin film device such as T).

[0002]

2. Description of the Related Art Conventionally, a crystalline silicon semiconductor thin film used for a thin film device such as a thin film insulating gate type field effect transistor (TFT) is formed on an insulating surface such as an insulating substrate by a plasma CVD method or a thermal CVD method. The obtained amorphous silicon film was crystallized in a device such as an electric furnace at a temperature of 600 ° C. or more for a long time of 12 hours or more. In particular, a longer heat treatment was required to obtain sufficient characteristics (high electrolytic effect mobility and high reliability).

[0003]

However, such a conventional method has many problems. One is low throughput and therefore high cost. For example, if it takes 24 hours for this crystallization step, 720 substrates must be processed at the same time if the processing time per substrate is 2 minutes. However, for example, in a commonly used tubular furnace, the number of substrates that can be processed at one time is 50 at most, and when only one apparatus (reaction tube) is used, it takes as long as 30 minutes per substrate. I got it. Ie 1
To achieve a processing time of 2 minutes per sheet, 15 reaction tubes had to be used. This meant that the scale of the investment increased and that the depreciation of the investment was large, and that it was reflected in the cost of the product.

Another problem was the temperature of the heat treatment. In general, substrates used for manufacturing TFTs are roughly classified into those made of pure silicon oxide such as quartz glass, and non-alkali borosilicate glass such as Corning No. 7059 (hereinafter, Corning 7059). Of these, the former has excellent heat resistance and can be handled in the same manner as a normal semiconductor integrated circuit wafer process, and therefore has no problem with temperature. However, its cost is high, and it exponentially increases exponentially as the substrate area increases. Therefore, at present, T
Used only in FT integrated circuits.

On the other hand, alkali-free glass has a sufficiently low cost as compared with quartz, but has a problem in heat resistance, and generally has a strain point of about 550 to 650 ° C., and particularly easily available materials at 600 ° C. or lower. Therefore, the heat treatment at 600 ° C. causes irreversible shrinkage and warpage of the substrate. In particular, it was remarkable in a large substrate having a diagonal of more than 10 inches. For the above reasons, regarding the crystallization of the silicon semiconductor film, the heat treatment condition of 550 ° C. or lower and within 4 hours has been indispensable for cost reduction. An object of the present invention is to provide a method for manufacturing a semiconductor that satisfies such conditions and a method for manufacturing a semiconductor device using such a semiconductor.

[0006]

DISCLOSURE OF THE INVENTION According to the present invention, a disordered crystalline state which can be said to be an amorphous state or a substantially amorphous state (for example, a state where a portion having good crystallinity and an amorphous portion are mixed) ), A film containing nickel, a particle, a cluster, etc. is formed on or under the silicon film in), and the temperature is lower than the crystallization temperature of normal amorphous silicon, preferably 20 to 15
It is characterized in that a crystalline silicon film is obtained by annealing at a temperature lower by 0 ° C., for example, a temperature of 580 ° C. or lower.

Regarding conventional crystallization of a silicon film, a method of solid phase epitaxial growth using a crystalline island-shaped film as a nucleus and using this as a seed crystal (see, for example, JP-A 1-21).
4110) has been proposed. However, with such a method, crystal growth hardly proceeded at a temperature of 600 ° C. or lower. In a silicon system, in general, in order to shift from an amorphous state to a crystalline state, the molecular chain in the amorphous state is divided, and the divided molecule is made into a state in which it does not bond with other molecules again, It goes through the process of recombining a molecule with a part of the crystal according to some crystalline molecule. However, in this process, the energy for breaking the first molecular chain and holding it in a state where it does not bind to other molecules is large,
This is a barrier in the crystallization reaction. To give this energy, at a temperature of about 1000 ° C for a few minutes,
Alternatively, at a temperature of about 600 ° C., several tens of hours are required, and the time exponentially depends on the temperature (= energy). Therefore, at 600 ° C. or lower, for example, 550 ° C., the crystallization reaction hardly progresses. I could not observe it. The conventional idea of solid phase epitaxial crystallization did not give a solution to this problem.

The present inventor has considered that the barrier energy of the above process is lowered by some catalytic action, in addition to the conventional idea of solid phase crystallization. The present inventors have found that nickel (Ni) is likely to bond with silicon and easily becomes nickel silicide (chemical formula NiSi _x , 0.4 ≦ x ≦ 2.5), and the lattice constant of nickel silicide is close to that of silicon crystal. I focused on that. Therefore, as a result of simulating the energy of the ternary system of crystalline silicon-nickel silicide-amorphous silicon, amorphous silicon easily reacts at the interface with nickel silicide, and amorphous silicon (silicon A) + nickel silicide (silicon B) → It became clear that a reaction of nickel silicide (silicon A) + crystalline silicon (silicon B) (silicon A and B indicate the position of silicon) occurs. The potential barrier of this reaction is sufficiently low and the reaction temperature is also low.

This reaction formula shows that nickel progresses while converting amorphous silicon into crystalline silicon. In fact, it became clear that the reaction started at 580 ° C or lower and was observed at 450 ° C. It was typically shown that crystallization can be performed at a temperature 20 to 150 ° C. lower than the crystallization temperature of ordinary amorphous silicon. As a matter of course, the higher the temperature, the faster the reaction proceeds.

A feature of the present invention is that the crystal growth progresses in a circular shape. This is because the movement of nickel or the like in the above reaction proceeds isotropically, which is different from the conventional crystallization in which the crystal linearly grows along the crystal lattice plane.

In the present invention, a film, particles, clusters or the like containing nickel such as nickel or its nickel silicide is used as a starting point, and from there, nickel is spread to the surroundings in accordance with the above reaction, whereby crystalline silicon is obtained. Expand the area of. Note that nickel oxide is not preferable as the material containing nickel. This is because nickel oxide is a stable compound and cannot initiate the above reaction.

The direction of crystal growth can be controlled by selectively providing a material containing nickel. Unlike conventional solid phase epitaxial growth, the crystalline silicon obtained by using such a method has a structure close to a single crystal with good crystallinity continuity over a long distance. It is convenient for use in devices.

Further, the amorphous silicon film as a starting material for this crystallization has a better result (crystallization rate) as the hydrogen concentration is lower. However, since hydrogen is released as crystallization progresses, the hydrogen concentration in the obtained silicon film was not so clearly correlated with the hydrogen concentration in the amorphous silicon film as the starting material. The hydrogen concentration in crystalline silicon according to the present invention is typically 0.
The content was 01 at% or more and 5 at% or less. Furthermore, in order to obtain good crystallinity, the amorphous silicon film in the carbon, nitrogen, oxygen concentration may as small, 1 × 10 ¹⁹
It is desired to be cm ⁻³ or less. Therefore, the material containing nickel used in the invention should also be selected in consideration of this point.

However, nickel itself is not preferable for silicon as a semiconductor material. Particularly, in the present invention, since nickel is almost uniformly diffused into the silicon film to achieve crystallization, a step of removing nickel is necessary. To do so, in an atmosphere containing chlorine or chlorine atoms such as chloride, 400 to 600 ° C.
It has been clarified that it is better to anneal. The appropriate annealing time was 0.1 to 6 hours. The longer the annealing, the lower the nickel concentration in the silicon film, but the annealing time may be determined in consideration of the manufacturing cost and the characteristics. Examples of chlorides include hydrogen chloride, various methane chlorides (CH ₃ Cl, etc.), various ethane chlorides (C ₂ H ₃ Cl).
₃ ) and various ethylene chlorides (C ₂ HCl ₃ etc.) were preferred. In particular, trichlorethylene (C ₂ HCl ₃ ) was a material that was easy to use. The concentration of nickel in the silicon film according to the present invention was typically 0.005% or less and 1 atomic% or less. Hereinafter, the present invention will be described in more detail with reference to examples.

[0015]

EXAMPLES Example 1 A method of forming a nickel film on a Corning 7059 glass substrate, crystallizing an amorphous silicon film using this as a catalyst to obtain a crystalline silicon film will be described with reference to FIG. On board 1,
An underlying silicon oxide film 2 having a thickness of 2000Å was formed by the plasma CVD method. Next, a nickel film 3 having a thickness of 1000 Å or less, for example 50 Å, was deposited by the sputtering method. The nickel film having a thickness of 100 Å or less had a shape that should be called a particle or a cluster composed of a plurality of particles rather than a film. When depositing nickel, use one substrate
Good results were obtained by heating to 00 to 500 ° C, preferably 180 to 250 ° C. This is because the adhesion between the underlying silicon oxide film and the nickel film is improved. It was also possible to use nickel silicide instead of nickel. (Fig. 1 (A))

After that, the amorphous silicon film 4 is formed by plasma CVD to 500 to 3000 Å, for example, 15
00Å was deposited, and hydrogen was discharged in a nitrogen atmosphere at 430 ° C. for 0.1 to 2 hours, for example 0.5 hour. (Fig. 1
(B))

Next, this is heated in an annealing furnace at 450 to 580.
Annealing was performed at 8 ° C., for example, 550 ° C. for 8 hours in a nitrogen atmosphere. In FIG. 1C, in the intermediate state, nickel diffuses from the nickel film (particles, clusters) previously formed, crystallization progresses, and the crystalline silicon region 5 expands into the amorphous region 4A. Show how it goes. After the crystallization is completed, the temperature is kept at 400 to 600 ° C., for example, 550 ° C., and trichloroethylene (C ₂ HCl is added).
₃ ) was diluted with hydrogen or oxygen to 1 to 10%, for example, 10%, introduced into an annealing furnace, and annealed for 0.1 to 2 hours, for example, 1 hour. As a result of the secondary ion mass spectrometry (SIMS) analysis of the thus chlorinated material, the concentration of nickel in the silicon film was 0.01 atomic%. By the way, in the case where the above-mentioned chlorination treatment was not carried out, the concentration of nickel was 5 atom%.
Also existed.

Example 2 This example is shown in FIG. A 2000 Å-thick underlying silicon oxide film 2 was formed on a Corning 7059 glass substrate 1 by a plasma CVD method.
Next, an amorphous silicon film 4 was deposited by plasma CVD to 500 to 3000 Å, for example 1500 Å, and hydrogen was degassed in a nitrogen atmosphere at 430 ° C. for 0.1 to 2 hours, for example 0.5 hour.

After that, the nickel film 3 is formed by the sputtering method.
Was deposited to a thickness of 1000 Å or less, for example, 80 Å. The nickel film having a thickness of 100 Å or less had a shape that should be called a particle or a cluster composed of a plurality of particles rather than a film. The substrate is 10 when the nickel film is formed.
Good results were obtained by heating to 0-500 ° C, preferably 180-250 ° C. This is because the adhesion between the underlying silicon film and the nickel film is improved. It was also possible to use nickel silicide instead of nickel. (Fig. 2
(A))

Next, this is heated in an annealing furnace at 450 to 580.
Annealing was performed at 4 ° C., for example, 550 ° C. for 4 hours in a nitrogen atmosphere. 2B, in the intermediate state, nickel diffuses from the previously formed nickel film (particles, clusters), crystallization progresses, and the crystalline silicon region 5 expands into the amorphous region 4A. Show how it goes. After the crystallization is completed, the temperature is kept at 400 to 600 ° C., for example, 580 ° C., and trichloroethylene (C ₂ HCl is added).
₃ ) was diluted with hydrogen or oxygen to 1 to 10%, for example 5%, introduced into an annealing furnace, and annealed for 0.1 to 2 hours, for example 0.5 hour.

Example 3 This example is shown in FIG. A 2000 Å-thick underlying silicon oxide film 32 was formed on a Corning 7059 glass substrate 31 by a plasma CVD method. Next, a nickel film 33 having a thickness of 10 is formed by a sputtering method.
Less than 00Å, for example, 80Å was deposited. (Fig. 3 (A))

Then, a photoresist is applied on the entire surface,
A resist pattern 34 was formed by using a known photolithography method. (FIG. 3 (B)) Furthermore, this is made into a suitable etchant, for example, 5 to 30%.
The nickel film in the exposed portion was removed by immersing in a hydrochloric acid solution. It can be similarly removed when nickel silicide is used. (Fig. 3 (C))

Then, the photoresist was peeled off by a known method to form a nickel film pattern 35. (Fig. 3
(D) After that, an amorphous silicon film is deposited by plasma CVD to 500 to 3000 Å, for example 1500 Å,
430 ° C. in nitrogen atmosphere for 0.1 to 2 hours, for example 0.5
Hydrogen was discharged for an hour. Next, this was annealed in a nitrogen atmosphere in an annealing furnace at 450 to 580 ° C., for example, 550 ° C. for 4 hours. In FIG. 3E, in the intermediate state, nickel diffuses from the nickel film pattern previously formed, and crystallization progresses, so that the crystalline silicon region 36 is formed.
Shows a state of expanding into the amorphous region 37.

After the crystallization was completed, the temperature was raised to 40 degrees.
0 to 600 ℃, keep it at 580 ℃, hydrogen chloride (HC
1) was diluted with hydrogen or oxygen to 1 to 10%, for example 1%, introduced into an annealing furnace, and annealed for 0.1 to 2 hours, for example 0.5 hour. As a result of the secondary ion mass spectrometry (SIMS) analysis of the thus chlorinated material, the concentration of nickel in the silicon film was 5 to 10 PPM. Incidentally, in the case where the above-mentioned chlorination treatment was not carried out, the concentration of nickel was as high as 1 atomic%.

[Embodiment 4] This embodiment is shown in FIG. A 2000 Å-thick underlying silicon oxide film 42 was formed on a Corning 7059 glass substrate 41 by plasma CVD. Next, an amorphous silicon film 43 was deposited to a thickness of 500 to 3000 Å, for example 1500 Å, by a plasma CVD method, and a nickel film 44 was subsequently deposited to a thickness of 1000 Å or less, for example 80 Å by a sputtering method. (Fig. 4
(A))

Then, a photoresist is applied on the entire surface,
A resist pattern 45 was formed by using a known photolithography method. (FIG. 4 (B)) Furthermore, a suitable etchant, for example 5 to 30%
The nickel film in the exposed portion was removed by immersing in a hydrochloric acid solution. (FIG. 4C) Then, the photoresist was peeled off by a known method to form a nickel film pattern 46. (Fig. 4 (D))

Then, in a nitrogen atmosphere at 430 ° C., 0.1 to
Hydrogen was discharged for 2 hours, for example, 0.5 hours. Next, this is placed in an annealing furnace at 450 to 580 ° C., for example 55
Annealing was performed at 0 ° C. for 4 hours in a nitrogen atmosphere. Figure 4 (E)
In the intermediate state, nickel diffuses from the previously formed nickel film pattern, crystallization progresses, and the crystalline silicon region 47 expands into the amorphous region 48.

After the crystallization was completed, the temperature was raised to 40 ° C.
Keeping at 0 to 600 ° C., for example, 580 ° C., trichloroethylene (C ₂ HCl ₃ ) at 1 to 10 with hydrogen or oxygen.
%, For example 5% and introduced into the annealing furnace to
Annealed for ~ 2 hours, for example 0.5 hours. As a result of the secondary ion mass spectrometry (SIMS) analysis of the thus chlorinated material, the concentration of nickel in the silicon film was 5 to 10 PPM. By the way, in the case where the above-mentioned chlorination treatment was not performed, the nickel concentration was 0.1 to 1 atomic%.

[Embodiment 5] This embodiment is shown in FIG. A 2000Å-thick underlying silicon oxide film 52 was formed on a Corning 7059 glass substrate 51 by a plasma CVD method. Then, a photoresist is applied on the entire surface, and a resist pattern 53 is formed by using a known photolithography method. (Figure 5 (A))

Next, a nickel film 54 having a thickness of 80 Å was deposited by the sputtering method. (FIG. 5B) Then, the photoresist was peeled off by a known method, and the nickel film adhered on the resist was also removed at the same time to form a nickel film pattern 55. (Fig. 5 (C))

After that, an amorphous silicon film of 1000 liters was deposited by the plasma CVD method. No hydrogen was released. Next, this is put in an annealing furnace at 450-5.
Annealing was performed in a nitrogen atmosphere at 80 ° C., for example, 550 ° C. for 4 hours. FIG. 5 (E) shows an intermediate state in which nickel diffuses from the nickel film pattern previously formed, crystallization progresses, and the crystalline silicon region 56 expands into the amorphous region 57. Show.

After the crystallization was completed, the temperature was raised to 55
The temperature was kept at 0 ° C., trichloroethylene (C ₂ HCl ₃ ) was diluted with hydrogen or oxygen to 1 to 10%, for example, 5%, and the mixture was introduced into an annealing furnace and annealed for 0.5 hour.

[Embodiment 6] This embodiment is shown in FIG. A 2000 Å-thick underlying silicon oxide film 62 was formed on a Corning 7059 glass substrate 61 by plasma CVD. After that, an amorphous silicon film 63 was deposited by 500 Å by the plasma CVD method. No hydrogen was released. Then, a photoresist was applied on the entire surface, and a resist pattern 64 was formed by using a known photolithography method. (Fig. 6 (A))

Next, a nickel film 65 having a thickness of about 100 Å was deposited by the electron beam evaporation method. (FIG. 6B) Then, the photoresist was peeled off by a known method, and the nickel film adhered on the resist was also removed at the same time to form a nickel film pattern 66. (Fig. 6 (C))

Then, this was annealed in an annealing furnace at 550 ° C. for 4 hours in a nitrogen atmosphere. FIG. 6 (E) shows an intermediate state in which nickel diffuses from the nickel film pattern previously formed, crystallization progresses, and the crystalline silicon region 67 expands into the amorphous region 68. Show. After crystallization was completed, the temperature was raised to 50
The temperature was kept at 0 ° C., hydrogen chloride (HCl) was diluted with hydrogen or oxygen to 1 to 10%, for example, 1%, and the mixture was introduced into an annealing furnace and annealed for 0.5 hour.

[0036]

INDUSTRIAL APPLICABILITY As described above, the present invention is epoch-making in the sense that it accelerates the crystallization of amorphous silicon at a low temperature and in a short time.
Since the devices and methods are extremely general and are excellent in mass productivity, the benefits to the industry are immeasurable.

For example, since the conventional solid phase growth method requires annealing for at least 24 hours,
If the substrate processing time per sheet was 2 minutes, 15 annealing furnaces were required.
Since it can be shortened within the time, the number of annealing furnaces can be reduced to 1/6 or less. The improvement in productivity and the reduction in capital investment resulting from this result in a reduction in the substrate processing cost, which in turn leads to a reduction in the TFT price and thereby a new demand. As described above, the present invention is industrially useful and is suitable for patent.

[Brief description of drawings]

FIG. 1 is a sectional view showing a process of an example. (Example 1)

FIG. 2 is a sectional view showing a process of an example. (Example 2)

FIG. 3 is a sectional view showing a process of the example. (Example 3)

FIG. 4 is a sectional view showing a process of the example. (Example 4)

FIG. 5 is a sectional view showing a process of the example. (Example 5)

FIG. 6 is a sectional view showing a process of the example. (Example 6)

[Explanation of symbols]

 1 ... Substrate 2 ... Base silicon oxide film 3 ... Nickel film (particles, clusters) 4 ... Amorphous silicon film 4A ... Amorphous silicon region 5 ... Crystal silicon region

Claims (6)

[Claims] 1. A first step of forming a nickel-containing body on a substrate, and the nickel-containing body comprising:
Second forming a silicon film in a substantially amorphous state
And after the second step, the substrate is annealed at a temperature lower than the crystallization temperature of normal amorphous silicon.
And a fourth step of performing annealing at 400 to 600 ° C. in an atmosphere containing chlorine or chloride after the above step. 2. The article according to claim 1, wherein the nickel-containing body used in the first step contains silicon and nickel, and the composition ratio thereof is silicon / nickel = 0.4 to 2.5. And a method for manufacturing a semiconductor. 3. The method for producing a semiconductor according to claim 1, wherein the annealing temperature in the third step is lower than the crystallization temperature of normal amorphous silicon by 20 to 150 ° C. 4. A first step of forming a silicon film in a substantially amorphous state on a substrate, a second step of forming an object containing nickel on the silicon film, and a second step.
The third step of annealing the substrate at a temperature lower than the crystallization temperature of normal amorphous silicon after the step of, and after the step of 400 to 400 in an atmosphere containing chlorine or chloride.
A fourth step of performing annealing at 600 ° C., and a semiconductor manufacturing method. 5. The article according to claim 4, wherein the nickel-containing body used in the first step contains silicon and nickel, and the composition ratio thereof is silicon / nickel = 0.4 to 2.5. And a method for manufacturing a semiconductor. 6. The method for manufacturing a semiconductor according to claim 4, wherein the annealing temperature in the third step is lower than the crystallization temperature of normal amorphous silicon by 20 to 150 ° C.