JPH088252A - Manufacture of semiconductor element - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method for manufacturing a semiconductor device capable of producing a semiconductor device having a low resistance at a metal / semiconductor interface and excellent characteristics with high productivity. [Structure] In a vacuum container, Ti, Mo, W containing impurities such as P or B as dopants in a concentration of 10 mol% or less in advance on a semiconductor substrate 1 made of polycrystalline silicon.
The metal thin film 2 is formed by a vacuum deposition method, a sputtering method, or the like. The sample temperature is set to 800 ° C. in an Ar atmosphere to diffuse the dopant element into the semiconductor substrate 1 to form the doping layer 3 and the metal silicide layer 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor element in the semiconductor industry, and more particularly to a method of manufacturing a semiconductor element useful for application to a semiconductor element such as a solar cell.

[0002]

2. Description of the Related Art In the manufacture of conventional semiconductor devices, a metal film for forming electrodes or the like is deposited after a dopant element is thermally diffused from a gas phase in a semiconductor substrate or thin film. There is a method, or a method of implanting an element serving as a dopant into a semiconductor by ion implantation and then performing a heat treatment to deposit a metal film.

An example of this conventional method will be described with reference to FIG. FIG. 4 is a schematic process diagram of a method for manufacturing a semiconductor device according to a conventional technique. In FIG. 4, 15 is a semiconductor substrate made of a polycrystalline silicon substrate or the like, and 16 is, for example, phosphorus (P).
Is a layer containing a dopant element in high concentration, 17 is a doping layer, and 18 is a metal thin film for electrodes. Generally, such a metal thin film is generally processed into a pattern according to a desired electrode shape and circuit.

The conventional method shown in FIG.
As shown in FIG. 4A, a doping layer 17 is formed by thermally diffusing an element serving as a dopant from a vapor phase, and at the same time, the doping element 17 is contained in a high concentration above the doping layer 17. Layer 16 is formed [Fig. 4
(B)]. Then, after the high concentration layer 16 of the dopant element is removed by using an appropriate etching solution such as hydrofluoric nitric acid [see (c) of FIG. 4], a metal thin film 18 is deposited thereon [see (d) of FIG. 4] Method Is.

[0005]

In the prior art, a method of thermally diffusing an element to be a dopant as shown in FIG. 4 from a gas phase and then depositing a metal film is known. Since the high concentration layer 16 is formed, there is a problem that the high concentration layer 16 near the surface must be removed.

Further, in the method of directly implanting ions into the semiconductor, since damage due to implantation remains in the semiconductor, it is necessary to perform heat treatment after implantation. In this heat treatment, a sample is usually taken out of the ion implantation equipment to the atmosphere and heat treatment is performed in another equipment. Therefore, an oxidized layer is generated due to the oxidation of the implantation damage layer, and it is necessary to remove this oxidized layer. There is a problem that the effective thickness of the doping layer is reduced. Further, in common with these conventional techniques, for example, when silicon is used, a metal film is deposited after the doping layer is formed, so that the doping layer may be oxidized during the formation of the doping layer depending on the doping layer forming atmosphere. ,
In any case, after the doping layer is formed, the sample is put into the atmosphere and the metal film is deposited in another device, so an oxide layer is generated when the sample is put into the atmosphere, and the oxidized layer is removed. Therefore, there is also a problem that the effective thickness of the doping layer is reduced.

The present invention solves the above-mentioned drawbacks of the conventional method, does not cause a high-concentration impurity layer or oxide layer, and has contact characteristics between a substrate made of a semiconductor or its thin film and a metal film deposited thereon. It is an object of the present invention to provide a method for manufacturing a semiconductor element, which is capable of producing a semiconductor element having improved characteristics, low resistance at the metal / semiconductor interface, and excellent characteristics.

The preferred embodiments of the present invention described below further have the following objects. That is, another object of the present invention is to provide a method of manufacturing a semiconductor device capable of forming a low resistance metal silicide at the metal / doping layer interface at the same time as forming a doping layer without being exposed to the atmosphere. To provide.

Still another object of the present invention is to provide a method for manufacturing a semiconductor device which is less likely to change the film performance due to heating and is relatively low in cost.

[0010]

In order to solve the above problems, any one of the following means is used in the method for manufacturing a semiconductor device of the present invention.

(1) Manufacture of a semiconductor device characterized in that a metal film containing an element serving as a dopant of the semiconductor is deposited on a substrate or a thin film made of a semiconductor and heat-treated at a temperature equal to or lower than the melting point of the metal film. Method.

(2) A metal film is deposited on a substrate or a thin film made of a semiconductor, elemental ions serving as a dopant for the semiconductor are implanted into the metal film, and then heat treatment is performed at a temperature equal to or lower than the melting point of the metal film. A method of manufacturing a semiconductor device, comprising:

(3) A semiconductor characterized in that a film and a metal film containing an element serving as a dopant of the semiconductor are deposited on a substrate or a thin film made of a semiconductor, and a heat treatment is performed at a temperature equal to or lower than the melting point of the metal film. Device manufacturing method.

(4) In the method of manufacturing a semiconductor device according to the present invention described in the above item (3), the film containing an element serving as a semiconductor dopant is a metal film containing an element serving as a semiconductor dopant. It is preferable.

(5) In the method for manufacturing a semiconductor device of the present invention described in any one of the above items (1) to (4), a substrate made of a semiconductor or a thin film is a substrate whose main constituent element is silicon. Alternatively, it is a thin film, and the metal component forming the metal film is a metal capable of forming a silicide, and the heat treatment is preferably performed at a temperature higher than the temperature at which the silicide of the metal is formed.

(6) In the method of manufacturing a semiconductor device of the present invention described in any of the above items (1) to (4), the substrate or thin film made of a semiconductor is a substrate or thin film made of a polycrystalline silicon semiconductor. Is preferred.

(7) In the method of manufacturing a semiconductor element of the present invention described in the above item (5), the substrate or thin film whose main constituent element is silicon is a substrate or thin film made of a polycrystalline silicon semiconductor. preferable.

[0018]

In the present invention, after depositing a metal film containing an element that becomes a semiconductor dopant on a substrate or a thin film made of a semiconductor, or by depositing a metal film, the element ions that become a dopant of the semiconductor are added to the metal. After implantation into the film, or after depositing a film and a metal film containing an element to be a dopant of the semiconductor, a heat treatment is performed at a temperature equal to or lower than the melting point of the metal film to increase the temperature near the interface between the metal and the doping layer. Since the impurity element of the concentration is not included,
The step of removing the high-concentration impurity layer as in the case of using the conventional technique is unnecessary. In addition, since the element serving as the dopant is diffused and activated by heat treatment in the state where the metal thin film is deposited, the metal / doping layer interface is not exposed to the atmosphere and an oxidized layer is not formed, resulting in good contact. The characteristics can be maintained. Further, since the metal film is heat-treated at a temperature equal to or lower than the melting point of the metal film, there is no fear that the pattern will be destroyed even if the metal film is patterned according to a desired electrode shape or circuit.

In addition to the above, in the method of manufacturing a semiconductor device described in the item (1), a metal film containing an element serving as a dopant of the semiconductor is deposited on a substrate or a thin film made of a semiconductor. Since it is a method of performing heat treatment at a temperature equal to or lower than the melting point of the metal film, it is possible to provide a method of manufacturing a semiconductor element, which has simple steps and is extremely easy to manufacture.

In addition to the above, in the method of manufacturing a semiconductor device described in the item (2), a method of implanting elemental ions serving as a semiconductor dopant by ion implantation into the metal film is adopted. Therefore, the amount of the element serving as a dopant contained in the metal film can be controlled with high accuracy, and unnecessary excess impurities (dopants) can be reduced. Therefore, an increase in electrical resistance between the metal film and the doped layer of the semiconductor can be further reduced, and a method for manufacturing a semiconductor device having good contact characteristics can be provided.

In addition to the above, in the case of the method for manufacturing a semiconductor device described in the above item (3) or (4),
Since a structure in which a metal film is separately deposited on a film containing an element serving as a dopant is adopted, a reciprocal layer of a film containing the element serving as a dopant and a metal film containing substantially no dopant serving as an electrode. It is not necessary to consider making the thickness of the film containing the element, which is the dopant as an impurity, more than necessary for the purpose other than the purpose of supplying the dopant. It is possible to reduce the thickness of the film containing the element which becomes the dopant which is the impurity such as the thickness of, and since the metal film deposited thereon does not substantially contain the dopant element which becomes the impurity, The resistance does not increase and the contact characteristics between the semiconductor film and the electrode metal can be improved.

The substrate or thin film made of a semiconductor is a substrate or thin film whose main constituent element is silicon, and the metal component constituting the metal film is a metal capable of forming a silicide. By adopting a preferred embodiment of the present invention in which the heat treatment is performed at a temperature higher than the formation temperature, it is possible to form a low resistance metal silicide at the metal / doping layer interface simultaneously with the formation of the doping layer without being exposed to the atmosphere. It is possible and preferable.

Further, by adopting a preferred embodiment of the present invention in which the substrate or thin film made of a semiconductor is a substrate or thin film made of a polycrystalline silicon semiconductor, the substrate or thin film made of a polycrystalline silicon semiconductor is compared with a semiconductor other than silicon. Since it has excellent heat resistance, it is less likely that the composition will change due to heat, can be manufactured more easily and can be cheaper than a semiconductor made of single crystal silicon, and has a higher film performance due to heating than an amorphous silicon semiconductor. It is preferable because it is unlikely to change.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first embodiment of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a process schematic view of one embodiment of a method for manufacturing a semiconductor device according to the present invention. In a vacuum container, on a semiconductor substrate 1 [FIG. 1 (a)] made of polycrystalline silicon, impurities such as P or B, which are dopants in advance, are 10 mol% or less (usually 10 mol% or less) by a vacuum deposition method, a sputtering method, or the like. A metal thin film 2 of Ti, Mo, W, etc., which is contained at a concentration of about 1 mol%) is formed [FIG. 1 (b)]. In this embodiment, a semiconductor substrate made of polycrystalline silicon (thickness: 200 μm) is used as the substrate,
A polycrystalline silicon thin film (for example, having a thickness of 1 μm or more) deposited on a substrate made of another material may be used depending on the configuration and structure of the device. At this time, the raw material (target) of the metal thin film
As described above, impurities such as P or B are previously added to 10
%, It is preferable to use a target made of a metal contained at a concentration of not more than%. However, when a single target is not used, two targets are used at the same time by using a metal target and a dopant impurity target separately. A thin film may be formed accordingly. Therefore, the formed metal thin film 2 contains a dopant element. As an example, the metal thin film 2 (thickness 100 nm) was formed by a sputtering method using a single target containing Ti as a metal and 5 mol% of B as a dopant element. After that, the temperature of the sample (substrate 1) is adjusted in a closed container, and heat treatment is performed in an atmosphere of an inert gas such as He or Ar or in a nitrogen atmosphere to diffuse the dopant element into the substrate 1 to form the p-type doping layer 3 Are formed [FIG. 1 (c)]. In this example, the sample temperature was set to 800 ° C. in an Ar atmosphere to perform diffusion. The heat treatment temperature at this time is not limited to the above temperature, and is a temperature higher than the temperature at which the dopant element is activated and lower than the melting point of the deposited metal film or the melting point of the polycrystalline silicon semiconductor substrate. From
A temperature range of 600 ° C to 1200 ° C is preferred. When the semiconductor material is silicon and the metal is a material that forms a silicide, as in this embodiment, the temperature is preferably equal to or higher than the temperature at which the metal silicide is formed. Therefore, in this embodiment, since the temperature at which TiSi ₂ is formed is 600 ° C. or higher, metal (Ti) is not formed when the doping layer is formed.
A low resistance silicon silicide (TiSi ₂ ) layer 4 of about 15 μΩ · cm is formed at the interface between the doped layer (Si) and the doping layer (Si). In addition, when Mo is used as the metal, 525 ° C. or higher, W
When using, the silicide layer is formed at 650 ° C. or higher.

By the method as described above, the formation of the metal thin film 2 and the formation of the doping layer 3 and the formation of the metal silicide layer 4 as shown in FIG. 1C are carried out simultaneously or successively. Moreover, since the doping layer 3 and the metal silicide layer 4 are formed at the interface sandwiched between the metal thin film 2 and the semiconductor substrate 1 made of polycrystalline silicon, they are not directly exposed to the atmosphere or the like. , There is no fear of oxidation. Therefore, it is possible to provide a semiconductor element having good productivity and excellent characteristics.

Next, the second embodiment of the present invention will be described in more detail. FIG. 2 is a process schematic view of another embodiment of the method for manufacturing a semiconductor device according to the present invention.
Semiconductor substrate 5 made of polycrystalline silicon in a vacuum container
(Thickness 200 μm) A metal thin film 6 of Ti, Mo, W or the like is formed on [FIG. 2 (a)] by a vacuum deposition method, a sputtering method or the like [FIG. 2 (b)], and then B or P is formed. Then, the dopant element ions 7 are implanted [FIG. 2 (c)].
As an example, the metal thin film 6 of Ti is formed by the sputtering method.
After the formation (thickness: 200 nm), P ⁺ ions with an energy of 100 keV were implanted at 10 ¹⁶ cm ^-2 . The temperature of the sample (substrate 5) is adjusted in a closed container, and He
Heat treatment in an inert gas such as Ar or Ar or nitrogen atmosphere,
A dopant element is diffused in the substrate 5 to form an n-type doping layer 8 [FIG. 2 (d)]. In this embodiment, Ar
Diffusion was performed by setting the sample temperature to 800 ° C. in the atmosphere. The heat treatment temperature at this time is not limited to the above temperature, since it is higher than the temperature at which the dopant element is activated, and is lower than the melting point of the deposited metal film or the melting point of the polycrystalline silicon substrate, 600 ℃ ~ 1200
A temperature range of ° C is preferred. When the semiconductor material is silicon and the metal is a material that forms a silicide, as in this embodiment, the temperature is preferably equal to or higher than the temperature at which the metal silicide is formed. Therefore, in this embodiment, TiSi
_{Since the} temperature at which ₂ is formed is 600 ° C. or higher, metal (Ti) and the doping layer (S
A low resistance silicide (TiSi ₂ ) layer 9 is formed at the interface i). By the method as described above, the formation of the metal thin film 6 and the doping layer 8 and the formation of the metal silicide layer 9 as shown in FIG. 2D can be performed simultaneously or successively. . Moreover, since the doping layer 8 and the metal silicide layer 9 are formed at the boundary surface sandwiched between the metal thin film 6 and the semiconductor substrate 5 made of polycrystalline silicon, the doping layer 8 and the metal silicide layer 9 are not directly exposed to the atmosphere or the like and are oxidized. There is no fear of Therefore, it is possible to provide a semiconductor element having good productivity and excellent characteristics. Further, since the dopant element ions 7 are implanted by ion implantation, the amount of the element serving as a dopant contained in the metal film can be controlled with high accuracy, and unnecessary unnecessary impurities (dopants) can be reduced. You can Therefore, it is possible to reduce an increase in electrical resistance between the metal film and the doping layer, and it is possible to manufacture a semiconductor device having good contact characteristics between the metal film and the doping layer.

Next, the third embodiment of the present invention will be described in more detail. FIG. 3 is a process schematic view of still another embodiment of the method for manufacturing a semiconductor device according to the present invention.

In a vacuum container, on a semiconductor substrate 10 (thickness 200 μm) [FIG. 3 (a)] made of polycrystalline silicon,
A film 11 containing an impurity element serving as a dopant (a metal film containing an element serving as a semiconductor dopant is used) and a metal thin film 12 are formed by a vacuum deposition method, a sputtering method, or the like [FIG. b)]. In order to form the metal film 11 containing the impurity element serving as the dopant, when a sputtering method is used, a metal target and an impurity target are separated, and two targets are alternately used to form a thin film. Further, in the case of a metal thin film deposited thereon, sputtering may be performed using only a metal target. As an example, as a metal, Ti,
A film 11 (thickness 10 nm) and a metal thin film 12 (thickness 100 nm) containing an impurity element serving as a dopant were formed by using P as a dopant element. After that, the temperature of the sample (substrate 10) is adjusted in a closed container, and He or Ar is used.
A heat treatment is performed in an atmosphere of an inert gas such as nitrogen or the like to diffuse the dopant element from the film 11 containing the impurity element into the substrate 10 to form the n-type doping layer 13 [FIG.
(C)]. In this embodiment, the sample temperature is set to 8 in Ar atmosphere.
The temperature was set to 00 ° C. and diffusion was performed. The heat treatment temperature at this time is not limited to the above-mentioned temperature, and is higher than the temperature at which the dopant element is activated, and is lower than the melting point of the deposited metal film or the melting point of the polycrystalline silicon substrate. , 600 ° C. to 1200 ° C. is preferable. When the semiconductor material is silicon and the metal is a material that forms a silicide, as in this embodiment, the temperature is preferably equal to or higher than the temperature at which the metal silicide is formed. Therefore, in this embodiment, since the temperature at which TiSi ₂ is formed is 600 ° C. or higher, a low resistance silicide (TiSi ₂ ) layer is formed at the interface between the metal (Ti) and the doping layer (Si) when the doping layer is formed. 14 is formed. By the method as described above, as shown in FIG. 3, the formation of the metal thin film 12, the formation of the doping layer 13, and the formation of the low resistance silicide layer 14 can be performed simultaneously or successively.
Moreover, since the doping layer 13 and the metal silicide layer 14 are formed at the interface sandwiched between the metal thin film 12 and the semiconductor substrate 10 made of polycrystalline silicon, the doping layer 13 and the metal silicide layer 14 are oxidized without being directly exposed to the atmosphere or the like. There is no fear. Therefore, it is possible to provide a semiconductor element with good productivity and excellent characteristics. Moreover, since the metal film to be the electrode is deposited in a state that it does not substantially contain the dopant and is deposited separately from the film containing the element to be the dopant, it is possible to include the element to be the dopant as the impurity. It is not necessary to consider that the film is made thicker than necessary for the purpose other than the purpose of supplying the dopant, and the film is made to have the minimum thickness necessary for supplying the dopant, so that the film contains an element serving as an impurity dopant. The thickness of the film can be reduced, and since the metal film serving as an electrode contains substantially no dopant, the resistance does not increase and the contact characteristics between the semiconductor film and the electrode metal can be improved.

In the present invention, the deposition means may be a method in which a raw material is supplied in a gas or liquid form and a solid film of a target substance can be formed on a predetermined object by an appropriate means such as heating. As long as the object of the present invention can be achieved, the method is not limited to the methods exemplified in the above-mentioned embodiments.

Further, the metal constituting the metal film is T
Examples thereof include i, Mo, W, Cr, Pt, Al, Au, and the like. From the viewpoint that a low resistance silicide can be formed especially when silicon is used as a semiconductor material, Ti, M
O, W and the like are preferable.

[0031]

According to the method of manufacturing a semiconductor device of the present invention, a metal film containing an element serving as a dopant of a semiconductor is deposited on a substrate or a thin film made of a semiconductor, or a metal film is deposited to deposit the semiconductor film. After implanting an element ion serving as a dopant into the metal film, or after depositing a film and a metal film containing an element serving as a dopant of the semiconductor, by heat treatment at a temperature equal to or lower than the melting point of the metal film, Since the high-concentration impurity element is not contained near the interface between the metal and the doping layer, the step of removing the high-concentration impurity layer as in the case of using the conventional technique is unnecessary. In addition, since diffusion / activation is performed in the state where the metal thin film is deposited, the metal / doping layer interface is not exposed to the atmosphere, an oxide layer is not likely to be generated, and an oxide layer removing step is not required, so that a good contact can be obtained. The characteristics can be maintained. Therefore, according to the present invention, it is possible to provide a method for manufacturing a semiconductor device capable of manufacturing a thin film device having good productivity and excellent characteristics.

Further, in the case of the invention of the method for manufacturing a semiconductor element of the first aspect of the present invention, in addition to the above-mentioned effects, it is possible to provide a method of manufacturing a semiconductor element which has a simple structure and is easier to manufacture.

Further, in the case of the invention of the method for manufacturing a semiconductor element of the second aspect of the present invention, in addition to the above effects, the amount of the element serving as a dopant contained in the metal film or the metal substrate can be controlled with high precision. It is possible to provide a method for manufacturing a semiconductor device capable of reducing unnecessary unnecessary impurities (dopants).

Further, in the case of the third and fourth inventions of the method for manufacturing a semiconductor device of the present invention, in addition to the above effects, the metal film to be an electrode is substantially free of a dopant. Since the film containing the element serving as a dopant is deposited separately from the metal film, the film containing the element serving as an impurity is required for the purpose other than the purpose of supplying the dopant. It is possible to reduce the thickness of the film containing the element that becomes the dopant that is an impurity, such as by setting the minimum thickness necessary for supplying the dopant, without having to consider the above thickness Since the metal film serving as the electrode contains substantially no dopant, the resistance does not increase and the contact characteristics between the semiconductor film and the electrode metal can be improved.

The substrate or thin film made of a semiconductor is a substrate or thin film whose main constituent element is silicon, and the metal component constituting the metal film is a metal capable of forming a silicide. According to a preferred embodiment of the present invention in which the heat treatment is performed at a temperature higher than the forming temperature, the metal silicide having a low resistance is formed at the metal / doping layer interface at the same time as the formation of the doping layer or continuously without being exposed to the air. It is possible to provide a method for manufacturing a semiconductor element, which can form layers and can obtain better contact characteristics. Therefore, it is possible to provide a method of manufacturing a semiconductor device capable of manufacturing a thin film device having excellent productivity and excellent characteristics.

By adopting a preferred embodiment of the present invention in which the substrate or thin film made of a semiconductor is a substrate or thin film made of a polycrystalline silicon semiconductor, the substrate or thin film made of a polycrystalline silicon semiconductor is superior to semiconductors other than silicon. Since it has excellent heat resistance, it is less likely that the composition will change due to heat, can be manufactured more easily and can be cheaper than a semiconductor made of single crystal silicon, and has a higher film performance due to heating than an amorphous silicon semiconductor. It is possible to provide a method of manufacturing a semiconductor device capable of manufacturing a device having excellent characteristics with little fear of change.

[Brief description of drawings]

FIG. 1 is a process schematic diagram of an example of a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a process schematic view of another embodiment of the method for manufacturing a semiconductor device according to the present invention.

FIG. 3 is a process schematic diagram of still another embodiment of the method for manufacturing a semiconductor device according to the present invention.

FIG. 4 is a process schematic diagram of a method for manufacturing a semiconductor device according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 semiconductor substrate 2 metal thin film 3 doping layer 4 silicide layer 5 semiconductor substrate 6 metal thin film 7 dopant element ion 8 doping layer 9 silicide layer 10 semiconductor substrate 11 film containing an impurity element 12 metal thin film 13 doping layer 14 silicide layer 15 semiconductor substrate 16 layer containing high concentration of dopant element 17 doping layer 18 metal thin film

Claims (7)

[Claims] 1. A substrate or thin film made of a semiconductor,
A method of manufacturing a semiconductor device, comprising depositing a metal film containing an element to be a dopant of the semiconductor, and heat-treating at a temperature equal to or lower than a melting point of the metal film. 2. A metal film is deposited on a substrate or a thin film made of a semiconductor, elemental ions serving as a dopant of the semiconductor are implanted into the metal film, and then heat treatment is performed at a temperature equal to or lower than a melting point of the metal film. A method for manufacturing a semiconductor device, comprising: 3. A semiconductor substrate or thin film,
A method of manufacturing a semiconductor device, comprising depositing a film containing a metal element as a dopant of a semiconductor and a metal film, and heat-treating the film at a temperature lower than a melting point of the metal film. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the film containing an element serving as a semiconductor dopant is a metal film containing an element serving as a semiconductor dopant. 5. A substrate or a thin film made of a semiconductor is a substrate or a thin film whose main constituent element is silicon, and a metal component constituting a metal film is a metal capable of forming a silicide. The method for manufacturing a semiconductor element according to claim 1, wherein the heat treatment is performed at a temperature of forming or higher. 6. The method of manufacturing a semiconductor device according to claim 1, wherein the substrate or thin film made of a semiconductor is a substrate or thin film made of a polycrystalline silicon semiconductor. 7. The method of manufacturing a semiconductor device according to claim 5, wherein the substrate or thin film whose main constituent element is silicon is a substrate or thin film made of a polycrystalline silicon semiconductor.