JP2020145205A - Negative ion generation device - Google Patents

Abstract

To provide a negative ion generation device capable of generating negative ions to irradiate an object in an appropriate state.SOLUTION: The negative ion generation device for irradiating an object with negative ions has a plasma source 7 for supplying plasma into a vacuum chamber 10 and means for adjusting a plasma generation state in the vacuum chamber 10. The means for adjusting the plasma generation state in the vacuum chamber 10 controls by a control unit 50 to supply the plasma into the vacuum chamber 10 intermittently.SELECTED DRAWING: Figure 4

Description

The present invention relates to a film forming system and a film forming method.

As a conventional film forming method, the one shown in Patent Document 1 is known. Patent Document 1 describes that an LED element is manufactured by forming a semiconductor film on a semiconductor substrate.

JP-A-2008-147608

As described above, by forming a semiconductor film on a semiconductor substrate, it is possible to form a high-quality semiconductor film having high orientation and low empty lattice defect concentration. However, while the above-mentioned semiconductor substrate can obtain a high-quality semiconductor film, there is a problem that the single crystal semiconductor substrate itself is expensive. Further, it is necessary to etch and remove polishing scratches on the surface of the substrate and carbides adhering during polishing, which causes a problem of increasing the process cost.

Therefore, an object of the present invention is to provide a film forming system and a film forming method capable of obtaining a high-quality semiconductor film while suppressing costs.

In order to solve the above problems, the film forming system according to the present invention is a film forming system for forming a film on a non-single crystal substrate, and includes a first film forming apparatus for forming a film by an ion plating method. A first film forming apparatus including a second film forming apparatus for forming a film on the downstream side of the first film forming apparatus, and the first film forming apparatus includes a first semiconductor material on a non-single crystal substrate. The semiconductor film is formed, and the second film forming apparatus forms a second semiconductor film containing the second semiconductor material on the first semiconductor film on the non-single crystal substrate.

In the film forming system according to the present invention, before the second semiconductor film is formed by the second film forming apparatus, the first film forming apparatus uses the ion plating method to form the first semiconductor film on the non-single crystal substrate. To form. By forming a film by the ion plating method in this way, a highly oriented polycrystalline film (single-axis crystal texture or uniaxial crystal texture) having an orientation order close to that of a single crystal (each crystallite has the same orientation order with each other). A first semiconductor film (called a film) can be formed. By forming a second semiconductor film on such a first semiconductor film, it is possible to obtain a second semiconductor film along the highly oriented first semiconductor film. Therefore, the second film forming apparatus has a higher orientation than the case where the second semiconductor film is formed on the first semiconductor film and the film is formed directly on the non-single crystal substrate. 2 semiconductor films can be obtained. As described above, even if a non-single crystal substrate, which is cheaper than a single crystal semiconductor substrate, is used, the film quality of the second semiconductor film can be obtained by forming the first semiconductor film with the first film forming apparatus. Can be improved. That is, it is possible to obtain a highly oriented semiconductor film equivalent to the highly oriented semiconductor film obtained by a conventional method of forming a semiconductor film after etching a single crystal semiconductor substrate to remove polishing scratches and carbides. From the above, it is possible to obtain a high-quality semiconductor film while suppressing the cost.

The first film forming apparatus may form the first semiconductor film thinner than the second semiconductor film. As described above, even if the first semiconductor film is thin, the film quality of the second semiconductor film can be sufficiently improved.

In the film forming system, the first semiconductor film is a polycrystalline alignment film, and the second semiconductor film may have an orientation order in the growth direction in the same direction as the growth direction of the first semiconductor film. .. As a result, the second semiconductor film formed by the film forming system has the same orientation of the first semiconductor film formed on the non-single crystal substrate, so that the second semiconductor film is aligned along the first semiconductor film. The orientation is aligned. Since the crystallites of the second semiconductor film are aligned in a single direction, it can be treated as a polycrystalline film having almost a single crystal (single orientation) and the same orientation.

The film forming system may further include a negative ion irradiating section that irradiates the first semiconductor film with negative ions after the first film forming apparatus has formed the first semiconductor film. By irradiating the first semiconductor film with negative ions by the negative ion irradiation unit, the orientation order of the first semiconductor film is further improved, and the density of atomic vacancies defects in the first semiconductor film is reduced. be able to. Thereby, the film quality of the second semiconductor film can be further improved.

The film forming method according to the present invention is a film forming method for forming a film on a non-single crystal substrate, and is a first forming step for forming a film by an ion plating method and a first forming step for forming a film. A second film forming step for later forming a film is provided, and in the first film forming step, a first semiconductor film containing a first semiconductor material is formed on a non-single crystal substrate, and a second film is formed. In the film forming step, a second semiconductor film containing the second semiconductor material is formed on the first semiconductor film on the non-single crystal substrate.

According to this film forming method, the same actions and effects as those of the above-mentioned film forming system can be obtained.

According to the present invention, a high-quality semiconductor film can be obtained while suppressing the cost.

It is a conceptual diagram which shows the film formation system which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the film formed on the non-single crystal substrate in Embodiment and Comparative Example. It is a conceptual diagram of the crystal structure of a membrane in an embodiment and a comparative example. It is the schematic sectional drawing which shows the structure of the 1st film forming apparatus. It is the schematic sectional drawing which shows the structure of the 1st film forming apparatus. It is the schematic sectional drawing which shows the structure of the 2nd film forming apparatus. It is a transmission electron microscope image of the membrane of the comparative example and the example. The reciprocal lattice map obtained by the measurement using the X-ray diffraction measurement method of the membrane of the comparative example and the Example is shown. It is a figure which shows the distribution of the inclination of the orientation plane of the crystal of the film of a comparative example and an Example. It is a graph which shows the electrical property of the film of the comparative example and the Example. It is a graph which shows the electrical property of the film of the comparative example and the Example. It is a figure for demonstrating the crystal lattice of ZnO.

Hereinafter, the film forming system according to the embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a conceptual diagram showing a film forming system according to an embodiment of the present invention. 2A and 2B are cross-sectional views showing the structure of a film formed on a non-single crystal substrate, and FIG. 2A shows the structure of a film formed by the film forming system shown in FIG. FIG. 2B shows the configuration of the film formed by the film forming system according to the comparative example. As shown in FIG. 1, the film forming system 100 according to the embodiment of the present invention has a first film forming apparatus 1 for forming a film by an ion plating method and a film forming apparatus 1 downstream of the first film forming apparatus 1. It is provided with a second film forming apparatus 2 for forming a film on the side. The first film forming apparatus 1 and the second film forming apparatus 2 are connected to each other by a conveying device or the like, and the non-single crystal substrate 3 may be automatically conveyed, but the operator manually conveys the film. You may.

As shown in FIG. 2A, in the film forming system 100, the first semiconductor film 4 is formed on the non-single crystal substrate 3, and the second semiconductor film 5 is formed on the first semiconductor film 4. A film is formed. The first semiconductor film 4 has a function of adjusting the crystal plane orientation of the second semiconductor film 5 as a base layer of the second semiconductor film 5. The second semiconductor film 5 formed on the non-single crystal substrate 3 and the first semiconductor film 4 in this way is for a hydrogen sensor sensitive material film, a light emitting diode light emitting layer film, and a silicon heterojunction type solar cell. It is used as a window layer, a window layer for CIGS thin-film solar cells, a semiconductor layer for power electronics, a plasmonics material layer for near-infrared wavelength communication, an antibacterial / bactericidal functional film, and the like.

The first film forming apparatus 1 forms a first semiconductor film 4 containing the first semiconductor material on the non-single crystal substrate 3. As a film forming method of the first film forming apparatus 1, an ion plating method of depositing an ionized metal on the surface of an object is adopted. Ga-added ZnO (GZO) is adopted as the first semiconductor material. In addition, as the first semiconductor material, B (boron) -added ZnO, Al (aluminum) -added ZnO, In (indium) -added ZnO, transition metal-added ZnO, GaN (gallium nitride), metal element-added GaN, Ga203 (gallium oxide) ) And other metal oxides, metal nitrides, and metal oxide nitrides (eg, CrON, etc.) may be used. As the non-single crystal substrate 3, a substrate made of a material other than the single crystal semiconductor, such as a glass substrate, a resin substrate, or a substrate of a non-single crystal semiconductor, may be adopted. As the non-single crystal substrate 3, a glass substrate in which glass is formed in a plate shape may be adopted. The type of glass used as the material of the glass substrate is not particularly limited, and types of glass such as blue plate glass, white plate glass, non-alkali glass, and quartz glass may be applied. Examples of the resin substrate and the non-single crystal semiconductor substrate include a sheet polymer (acrylic resin, cycloolefin polymer, etc.) and a flexible polymer film (polyethylene terephthalate, polyethylene naphthalate, etc.). The first film forming apparatus 1 forms the first semiconductor film 4 thinner than the second semiconductor film 5. Specifically, the thickness of the first semiconductor film 4 may be, for example, 50 nm or less, and further may be 10 nm or less. The lower limit of the thickness of the first semiconductor film 4 is not particularly limited, but for example, the thickness of the first semiconductor film 4 may be 2 nm or more. It is desirable that the thickness of the first semiconductor film 4 is made thinner as long as the function of the second semiconductor film 5 is not affected.

Further, the film forming system 100 further includes a negative ion irradiation unit 24 that irradiates the first semiconductor film 4 with negative ions after the first film forming apparatus 1 has formed the first semiconductor film 4. In the present embodiment, the negative ion irradiation unit 24 is incorporated in the first film forming apparatus 1, and the first film forming apparatus 1 attaches to the first semiconductor film 4 and the first semiconductor film 4. Irradiation of negative ions can be performed. However, the negative ion irradiation unit 24 does not have to be incorporated in the first film forming apparatus 1, and may be configured as a device separate from the first film forming apparatus 1. The negative ion is a substance having a positive electron affinity, and the negative ion of oxygen may be adopted. As negative ions, H, C, O, F, Si, S, Cl, Br, I, etc. are used for atoms, and O ₂ , Cl ₂ , Br ₂ , I ₂ , CH, OH, CN for molecules. , HCl, HBr, NH ₂ , N ₂ O, NO ₂ , CCl ₄ , and SF _{6 and the} like may be employed. The negative ions to be irradiated are not limited to the same elements as the elements contained in the first semiconductor film 4 or the second semiconductor film 5, but may be different elements. The amount of negative ions irradiated to the first semiconductor film 4 by the negative ion irradiation unit 24 is not particularly limited, but for example, an amount of 1 × 10 ¹⁹ cm ^-3 or more with respect to the irradiated film. You may irradiate with negative ions. Further, the irradiation amount of negative ions may be such an amount that surface precipitation or grain boundary precipitation occurs. In this case, the irradiated negative ions diffuse from the first semiconductor film 4 to the second semiconductor film and function as an effective dopant. The detailed configuration of the negative ion irradiation unit 24 will be described later together with the description of the first film forming apparatus 1.

The second film forming apparatus 2 forms a second semiconductor film 5 containing the second semiconductor material on the first semiconductor film 4 on the non-single crystal substrate 3. A sputtering method may be adopted as the film forming method of the second film forming apparatus 2. In the sputtering method, a second semiconductor material is placed in a vacuum chamber as a target, and an ionized rare gas element or the like collides with the target surface to eject atoms of the second semiconductor material and attach them to the surface of an object. The method. However, the film forming method of the second film forming apparatus 2 is not limited to the sputtering method, and various film forming methods such as a molecular beam epitaxy (MBE) method and an electron beam vapor deposition method may be adopted. As the second semiconductor material, Al-added ZnO (AZO) is adopted. In addition, as the second semiconductor material, GaN, AlN, Ga ₂ O ₃ , B (boron) -added ZnO, Al (aluminum) -added ZnO, In (indium) -added ZnO, transition metal-added ZnO, GaN (gallium nitride), Metal oxides such as GaN with metal elements added and Ga203 (gallium oxide), metal nitrides, metal nitride nitrides and the like may be adopted. The thickness of the second semiconductor film 5 is not particularly limited, but can be, for example, 50 nm or more.

(First film forming apparatus 1)
Next, an example of the configuration of the first film forming apparatus 1 will be described with reference to FIGS. 4 and 5. As shown in FIGS. 4 and 5, the first film forming apparatus 1 is an ion plating apparatus used in the so-called ion plating method. For convenience of explanation, FIGS. 4 and 5 show an XYZ coordinate system. The Y-axis direction is the direction in which the non-single crystal substrate 3 described later is conveyed. The X-axis direction is a position where the non-single crystal substrate 3 and the hearth mechanism described later face each other. The Z-axis direction is a direction orthogonal to the Y-axis direction and the X-axis direction.

The first film forming apparatus 1 starts from a state in which the non-single crystal substrate 3 is upright or upright so that the thickness direction of the non-single crystal substrate 3 is the horizontal direction (X-axis direction in FIGS. 4 and 5). This is a so-called vertical film forming apparatus in which the non-single crystal substrate 3 is arranged and conveyed in the vacuum chamber 10 in an inclined state. In this case, the X-axis direction is the horizontal direction and the plate thickness direction of the non-single crystal substrate 3, the Y-axis direction is the horizontal direction, and the Z-axis direction is the vertical direction. The first film forming apparatus 1 is a so-called horizontal film forming apparatus in which the non-single crystal substrate 3 is arranged and conveyed in a vacuum chamber so that the thickness direction of the non-single crystal substrate 3 is substantially vertical. It may be. In this case, the Z-axis and Y-axis directions are horizontal, and the X-axis direction is the vertical direction and the plate thickness direction. Hereinafter, a vertical film forming apparatus will be described as an example.

The first film forming apparatus 1 includes a vacuum chamber 10, a transport mechanism 13, a film forming section 14, a negative ion irradiation section 24, and a magnetic field generating coil 30.

The vacuum chamber 10 houses the non-single crystal substrate 3 and performs a film forming process. The vacuum chamber 10 has a transport chamber 10a for transporting the non-single crystal substrate 3 on which the film of the film-forming material Ma is formed, a film-forming chamber 10b for diffusing the film-forming material Ma, and a beam shape from the plasma source 7. It has a plasma port 10c that receives the irradiated plasma P into the vacuum chamber 10. The transport chamber 10a, the film forming chamber 10b, and the plasma port 10c communicate with each other. The transport chamber 10a is set along a predetermined transport direction (arrow A in the figure) along the Y-axis. Further, the vacuum chamber 10 is made of a conductive material and is connected to a ground potential.

The film forming chamber 10b has a pair of side walls along the transport direction (arrow A) and a pair of side walls 10h and 10i along the direction intersecting the transport direction (arrow A) (Z-axis direction) as the wall portion 10w. , A bottom wall 10j arranged intersecting the X-axis direction.

The transport mechanism 13 transports the non-single crystal substrate holding member 16 that holds the non-single crystal substrate 3 in a state of facing the film forming material Ma in the transport direction (arrow A). For example, the non-single crystal substrate holding member 16 is a frame body that holds the outer peripheral edge of the non-single crystal substrate 3. The transport mechanism 13 is composed of a plurality of transport rollers 15 installed in the transport chamber 10a. The transfer rollers 15 are arranged at equal intervals along the transfer direction (arrow A), and transfer in the transfer direction (arrow A) while supporting the non-single crystal substrate holding member 16. As the non-single crystal substrate 3, for example, a plate-shaped member such as a non-single crystal substrate or a plastic substrate is used.

Subsequently, the configuration of the film forming portion 14 will be described in detail. The film forming section 14 adheres the particles of the film forming material Ma to the non-single crystal substrate 3 by the ion plating method. The film forming unit 14 includes a plasma source 7, a steering coil 25, a hearth mechanism 22, and a wheel hearth 6.

The plasma source 7 is, for example, a pressure gradient type plasma gun, and its main body is connected to the film forming chamber 10b via a plasma port 10c provided on the side wall of the film forming chamber 10b. The plasma source 7 generates plasma P in the vacuum chamber 10. The plasma P generated in the plasma source 7 is emitted in a beam shape from the plasma port 10c into the film forming chamber 10b. As a result, plasma P is generated in the film forming chamber 10b.

One end of the plasma source 7 is blocked by the cathode 60. A first intermediate electrode (grid) 61 and a second intermediate electrode (grid) 62 are concentrically arranged between the cathode 60 and the plasma port 10c. An annular permanent magnet 61a for converging the plasma P is built in the first intermediate electrode 61. An electromagnet coil 62a is also built in the second intermediate electrode 62 in order to converge the plasma P. The plasma source 7 also has a function as a negative ion irradiation unit 24, which will be described later. Details of this will be described later in the description of the negative ion irradiation unit 24.

The steering coil 25 is provided around the plasma port 10c to which the plasma source is mounted. The steering coil 25 guides the plasma P into the film forming chamber 10b. The steering coil 25 is excited by a power source (not shown) for the steering coil.

The hearth mechanism 22 holds the film-forming material Ma. The hearth mechanism 22 is provided in the film forming chamber 10b of the vacuum chamber 10 and is arranged in the negative direction in the X-axis direction when viewed from the transport mechanism 13. The hearth mechanism 22 has a main anode for guiding the plasma P emitted from the plasma source 7 to the film forming material Ma or a main anode 17 for guiding the plasma P emitted from the plasma source 7.

The main hearth 17 has a tubular filling portion 17a in which the film-forming material Ma is filled and extends in the positive direction in the X-axis direction, and a flange portion 17b protruding from the filling portion 17a. Since the main hearth 17 is maintained at a positive potential with respect to the ground potential of the vacuum chamber 10, the plasma P is sucked. A through hole 17c for filling the film forming material Ma is formed in the filling portion 17a of the main hearth 17 on which the plasma P is incident. Then, the tip portion of the film forming material Ma is exposed to the film forming chamber 10b at one end of the through hole 17c.

When the film-forming material Ma is made of an insulating substance, when the main hearth 17 is irradiated with plasma P, the main hearth 17 is heated by the current from the plasma P, and the tip portion of the film-forming material Ma evaporates or sublimates. The film-forming material particles (evaporated particles) Mb ionized by the plasma P diffuse into the film-forming chamber 10b. Further, when the film forming material Ma is made of a conductive substance, when the main hearth 17 is irradiated with plasma P, the plasma P is directly incident on the film forming material Ma, and the tip portion of the film forming material Ma is heated and evaporated. Alternatively, the film-forming material particles Mb that have been sublimated and ionized by the plasma P diffuse into the film-forming chamber 10b. The film-forming material particles Mb diffused in the film-forming chamber 10b move in the positive direction of the X-axis of the film-forming chamber 10b and adhere to the surface of the non-single crystal substrate 3 in the transport chamber 10a. The above-mentioned first semiconductor material is adopted as the film forming material Ma. GZO exemplified as the first semiconductor material is a conductive material. The film-forming material Ma is a solid material formed into a cylindrical shape having a predetermined length, and a plurality of film-forming materials Ma are filled in the hearth mechanism 22 at one time. Then, the film-forming material Ma is X of the hearth mechanism 22 according to the consumption of the film-forming material Ma so that the tip portion of the film-forming material Ma on the most advanced side maintains a predetermined positional relationship with the upper end of the main hearth 17. It is pushed out sequentially from the negative direction side.

The ring hearth 6 is an auxiliary anode having an electromagnet for inducing the plasma P. The ring hearth 6 is arranged around the filling portion 17a of the main hearth 17 that holds the film forming material Ma. The ring hearth 6 has an annular coil 9, an annular permanent magnet portion 20, and an annular container 12, and the coil 9 and the permanent magnet portion 20 are housed in the container 12. In the present embodiment, the coil 9 and the permanent magnet portion 20 are installed in this order in the X negative direction when viewed from the transport mechanism 13, but the permanent magnet portion 20 and the coil 9 may be installed in this order in the X negative direction. The ring hearth 6 controls the direction of the plasma P incident on the film forming material Ma or the direction of the plasma P incident on the main hearth 17 according to the magnitude of the current flowing through the coil 9.

Subsequently, the configuration of the negative ion irradiation unit 24 will be described in detail. The negative ion irradiation unit 24 includes a plasma source 7, a raw material gas supply unit 40, a control unit 50, and a circuit unit 34. Some functions included in the control unit 50 and the circuit unit 34 also belong to the film forming unit 14 described above.

As the plasma source 7, the same plasma source 7 as that of the film forming portion 14 described above is used. That is, in the present embodiment, the plasma source 7 of the film forming unit 14 is also used as the plasma source 7 of the negative ion irradiation unit 24. The plasma source 7 functions not only as a film forming unit 14 but also as a negative ion irradiation unit 24. The film forming unit 14 and the negative ion irradiation unit 24 may have different plasma sources different from each other.

The plasma source 7 intermittently generates plasma P in the film forming chamber 10b. Specifically, the plasma source 7 is controlled by a control unit 50 described later so as to intermittently generate plasma P in the film forming chamber 10b. This control will be described in detail in the description of the control unit 50 described later.

The raw material gas supply unit 40 is arranged outside the vacuum chamber 10. The raw material gas supply unit 40 supplies oxygen gas, which is a raw material gas for negative oxygen ions, into the vacuum chamber 10 through a gas supply port 41 provided on the side wall (for example, the side wall 10h) of the film forming chamber 10b. The raw material gas supply unit 40 starts supplying oxygen gas when, for example, the film formation processing mode is switched to the oxygen negative ion generation mode. Further, the raw material gas supply unit 40 may continue to supply oxygen gas in both the film forming process mode and the oxygen negative ion generation mode.

The position of the gas supply port 41 is preferably a position near the boundary between the film forming chamber 10b and the transport chamber 10a. In this case, since the oxygen gas from the raw material gas supply unit 40 can be supplied to the vicinity of the boundary between the film forming chamber 10b and the transport chamber 10a, the oxygen negative ions described later are generated near the boundary. Therefore, the generated negative oxygen ions can be suitably attached to the non-single crystal substrate 3 in the transport chamber 10a. The position of the gas supply port 41 is not limited to the vicinity of the boundary between the film forming chamber 10b and the transport chamber 10a.

The control unit 50 is arranged outside the vacuum chamber 10. The control unit 50 switches the switching unit included in the circuit unit 34. The switching of the switching unit by the control unit 50 will be described in detail below together with the description of the circuit unit 34.

The circuit unit 34 has a variable power supply 80, a first wiring 71, a second wiring 72, resistors R1 to R4, and short-circuit switches SW1 and SW2.

The variable power supply 80 applies a negative voltage to the cathode 60 of the plasma source 7 and a positive voltage to the main hearth 17 of the hearth mechanism 22 across the vacuum chamber 10 at the ground potential. As a result, the variable power supply 80 generates a potential difference between the cathode 60 of the plasma source 7 and the main hearth 17 of the hearth mechanism 22.

The first wiring 71 electrically connects the cathode 60 of the plasma source 7 to the negative potential side of the variable power supply 80. The second wiring 72 electrically connects the main hearth 17 (anode) of the hearth mechanism 22 to the positive potential side of the variable power supply 80.

One end of the resistor R1 is electrically connected to the first intermediate electrode 61 of the plasma source 7, and the other end is electrically connected to the variable power source 80 via the second wiring 72. That is, the resistor R1 is connected in series between the first intermediate electrode 61 and the variable power supply 80.

One end of the resistor R2 is electrically connected to the second intermediate electrode 62 of the plasma source 7, and the other end is electrically connected to the variable power source 80 via the second wiring 72. That is, the resistor R2 is connected in series between the second intermediate electrode 62 and the variable power supply 80.

One end of the resistor R3 is electrically connected to the wall portion 10w of the film forming chamber 10b, and the other end is electrically connected to the variable power supply 80 via the second wiring 72. That is, the resistor R3 is connected in series between the wall portion 10w of the film forming chamber 10b and the variable power supply 80.

One end of the resistor R4 is electrically connected to the wheel hearth 6, and the other end is electrically connected to the variable power supply 80 via the second wiring 72. That is, the resistor R4 is connected in series between the wheel hearth 6 and the variable power supply 80.

The short-circuit switches SW1 and SW2 are switching units that can be switched to the ON / OFF state by receiving the command signal from the above-mentioned control unit 50, respectively.

The short-circuit switch SW1 is connected in parallel to the resistor R2. The short-circuit switch SW1 is switched on / off by the control unit 50 depending on whether it is in the film formation processing mode or the oxygen negative ion mode. The short-circuit switch SW1 is turned off in the film formation processing mode. As a result, in the film forming processing mode, the second intermediate electrode 62 and the variable power supply 80 are electrically connected to each other via the resistor R2, so that between the second intermediate electrode 62 and the variable power supply 80. It is difficult for current to flow through. As a result, the plasma P from the plasma source 7 is emitted into the vacuum chamber 10 and incident on the film forming material Ma (see FIG. 4).

On the other hand, in the oxygen negative ion generation mode, the short-circuit switch SW1 intermittently generates the plasma P from the plasma source 7 in the vacuum chamber 10, so that the ON / OFF state is switched at predetermined intervals by the control unit 50. When the short-circuit switch SW1 is switched to the ON state, the electrical connection between the second intermediate electrode 62 and the variable power supply 80 is short-circuited, so that a current flows between the second intermediate electrode 62 and the variable power supply 80. It flows. That is, a short-circuit current flows through the plasma source 7. As a result, the plasma P from the plasma source 7 is not emitted into the vacuum chamber 10.

When the short-circuit switch SW1 is switched to the OFF state, the second intermediate electrode 62 and the variable power supply 80 are electrically connected to each other via the resistor R2, so that the second intermediate electrode 62 and the variable power supply 80 are connected to each other. It is difficult for current to flow between them. As a result, the plasma P from the plasma source 7 is emitted into the vacuum chamber 10. In this way, the ON / OFF state of the short-circuit switch SW1 is switched by the control unit 50 at predetermined intervals, so that plasma P from the plasma source 7 is intermittently generated in the vacuum chamber 10. That is, the short-circuit switch SW1 is a switching unit that switches between supplying and shutting off the plasma P into the vacuum chamber 10.

The short-circuit switch SW2 is connected in parallel to the resistor R4. The short-circuit switch SW2 is turned on / off by the control unit 50, for example, depending on whether it is in the standby mode or the film forming process mode, which is the state before the transfer of the non-single crystal substrate 3 before the film forming process mode. Is switched. The short-circuit switch SW2 is turned on in the standby mode. As a result, the electrical connection between the wheel hearth 6 and the variable power supply 80 is short-circuited, so that it becomes easier to pass a current through the wheel hearth 6 than the main hearth 17, and wasteful consumption of the film forming material Ma can be prevented. it can.

On the other hand, the short-circuit switch SW2 is turned off in the film formation processing mode. As a result, since the wheel hearth 6 and the variable power supply 80 are electrically connected via the resistor R4, it becomes easier to pass a current through the main hearth 17 than the wheel hearth 6, and the emission direction of the plasma P is preferably formed. It can be directed to the material Ma. The short-circuit switch SW2 may be in either the ON state or the OFF state in the oxygen negative ion generation mode.

The magnetic field generation coil 30 is provided in the vacuum chamber 10 between the film forming chamber 10b and the transport chamber 10a. The magnetic field generation coil 30 is arranged between, for example, the hearth mechanism 22 and the transfer mechanism 13. More specifically, the magnetic field generation coil 30 is located so as to be interposed between the end of the film forming chamber 10b on the transport chamber 10a side and the end of the transport chamber 10a on the film forming chamber 10b side. The magnetic field generating coil 30 has a pair of coils 30a and 30b facing each other. The coils 30a and 30b face each other in a direction intersecting, for example, in a direction from the film forming chamber 10b toward the transport chamber 10a (direction from the hearth mechanism 22 toward the transport mechanism 13).

The magnetic field generating coil 30 is not excited in the film forming process mode, but is excited by a power source (not shown) for the magnetic field generating coil 30 in the oxygen negative ion generation mode. Here, the film forming process mode is a mode in which the film forming process is performed on the non-single crystal substrate 3 in the vacuum chamber 10. The oxygen negative ion generation mode is a mode in which oxygen negative ions are generated for adhering to the surface of the film formed on the non-single crystal substrate 3 in the vacuum chamber 10. The magnetic field generating coil 30 has a magnetic field line extending in a direction intersecting the direction from the film forming chamber 10b toward the transport chamber 10a (the direction from the hearth mechanism 22 toward the transport mechanism 13) by being excited in the oxygen negative ion generation mode. A sealing magnetic field M is formed in the vacuum chamber 10 (see FIG. 5). By generating such a sealing magnetic field M, the magnetic field generation coil 30 suppresses the inflow of electrons in the film forming chamber 10b into the transport chamber 10a. The magnetic field line of the sealing magnetic field M may have a portion extending in a direction substantially parallel to the transport direction (arrow A) of the non-single crystal substrate 3, for example. The switching of the power ON / OFF state for the magnetic field generation coil 30 may be controlled by the control unit 50 described later. The magnetic field generation coil 30 is covered with a case 31 so that the film forming material Ma does not accumulate. The magnetic field generation coil 30 does not have to be covered with the case 31.

(Second film forming apparatus 2)
FIG. 6 is a schematic configuration diagram of the second film forming apparatus 2. FIG. 6 illustrates a configuration when a sputtering method is adopted as the film forming method of the second film forming apparatus 2. As shown in FIG. 6, the second film forming apparatus 2 forms the second semiconductor film 5 on the non-single crystal substrate 3 by a sputtering method. Although the first semiconductor film 4 is formed on the surface of the non-single crystal substrate 3 here, it is simply referred to as “non-single crystal substrate 3” in the following description. The second film forming apparatus 2 includes a vacuum chamber 102, a target 103 provided in the vacuum chamber 102, a power source 106 that generates plasma by electric discharge, and a heating unit 118 that heats the non-single crystal substrate 3. It includes a control unit 130 that controls the second film forming apparatus 2. The second film forming apparatus 2 generates plasma in a dilute argon atmosphere in a vacuum, and causes positive ions in the plasma to collide with the film forming material (target 103) to eject metal atoms to form a non-single crystal substrate. 3 The film is formed by adhering it on the top.

The vacuum chamber 102 is a container that can accommodate the non-single crystal substrate 3, and is adjacent to the sputtering chamber 107 in which sputtering is performed, the exhaust chamber 108 adjacent to the front stage side of the sputtering chamber 107, and the rear stage side of the sputtering chamber 107. It has a vent chamber 109 to be used. The vacuum chamber 102 is provided with a non-single crystal substrate arranging portion 120 capable of arranging the non-single crystal substrate 3 and transporting the arranged non-single crystal substrate 3 in a predetermined transport direction A. The non-single crystal substrate arranging unit 120 includes a plurality of transfer rollers 111 provided along the transfer direction A. The non-single crystal substrate 3 is placed on the transfer roller 111 and is conveyed in the transfer direction A by the transfer roller 111. The non-single crystal substrate 3 may be arranged on the non-single crystal substrate arranging portion 120 in a state of being placed on the transport tray.

The target 103 is a flat plate-shaped member made of a film-forming material or a part of the film-forming material (composition material). A cylindrical member can also be used as the target 103. The target 103 is arranged in the sputtering chamber 107 so as to face the non-single crystal substrate 3. The target 103 has a front surface 103a facing the non-single crystal substrate arranging portion 120 (opposing the non-single crystal substrate 3) and a back surface 103b on the opposite side. A sputtering space C is formed between the target 103 and the non-single crystal substrate 3. The target 103 is formed by firing the powder of the second semiconductor material.

Further, the second film forming apparatus 2 is connected to each of the sputter chamber 107, the exhaust chamber 108, and the vent chamber 109, and is a turbo molecular pump (TMP) 112 for evacuating each chamber. The gate valve 113 provided between the sputter chamber 107, the exhaust chamber 108, and the vent chamber 109, the inlet portion of the exhaust chamber 108, and the outlet portion of the vent chamber 109, and the exhaust chamber 108 and the vent chamber 109. It includes a dry pump 114 connected to each.

Further, in the second film forming apparatus 2, the argon bomb 116 filled with argon (Ar) gas as an inert gas, which is an atmospheric gas, and the argon gas in the argon bomb 116 are mixed at a predetermined flow rate in the sputtering chamber 107. It is provided with a mass flow controller (MFC; Mass Flow Controller) 117 which is a gas flow controller to be supplied to the inside. In addition, xenon (Xe) or krypton (Kr) may be used as an atmospheric gas. Further, the second film forming apparatus 2 is a mass flow controller which is a gas flow controller that supplies an oxygen cylinder 122 filled with oxygen gas inside and the oxygen gas in the oxygen cylinder 122 into the sputter chamber 107 at a predetermined flow rate. It is equipped with 121.

In the vacuum chamber 102, below the non-single crystal substrate 3 (on the back side of the film-forming surface), heating portions 118 composed of heaters are arranged side by side in the transport direction A. The heating unit 118 is provided in each of the sputtering chamber 107, the exhaust chamber 108, and the vent chamber 109, but a part of the heating unit 118 may be omitted. Further, the mounting position of the heating unit 118 in the vacuum chamber 102 is not particularly limited, and may be arranged anywhere as long as the non-single crystal substrate 3 can be heated.

The electric power source 106 is for supplying electric power to the target 103 to cause an electric discharge. The power source 106 includes a DC power supply and a high frequency power supply. The high frequency power supply can superimpose a high frequency on the power supplied by the DC power supply 33. The frequency of the high frequency power supply 36 is 13 to 41 MHz.

The film forming method using the film forming system 100 as described above will be described. The film forming method includes a first film forming step of forming a film by an ion plating method and a second forming step of forming a film after the first forming step. In the first film forming step, the first semiconductor film 4 containing the first semiconductor material is formed on the non-single crystal substrate 3. In the second film forming step, a second semiconductor film 5 containing the second semiconductor material is formed on the first semiconductor film 4 on the non-single crystal substrate 3. A negative ion irradiation step of irradiating the first semiconductor film 4 with negative ions is executed between the first film forming step and the second film forming step.

Next, the actions and effects of the film forming system 100 and the film forming method according to the present embodiment will be described.

First, as a comparative example, as shown in FIG. 2B, a film forming system for directly forming the second semiconductor film 5 on the non-single crystal substrate 3 will be described. The non-single crystal substrate 3 is an inexpensive substrate as compared with a semiconductor substrate such as a silicon wafer or sapphire. However, unlike those semiconductor substrates, the non-single crystal substrate 3 is not a substrate composed of good crystal orientation, and therefore, a second semiconductor is used on the non-single crystal substrate 3 by a sputtering method or other film forming method. Even if the film 5 is formed, it has a polycrystalline structure (mixed orientation) in which the orientations are not uniform. For example, as shown in FIG. 3 (b), the crystallite 5a is finely oriented in multiple directions. In this configuration, many grain boundaries that are not aligned are formed. When the electron E passes through such a second semiconductor film 5, in addition to the scattering caused by passing through the crystallite, the influence of the scattering generated at the grain boundary appears.

On the other hand, in the film forming system 100 according to the present embodiment, the first film forming apparatus 1 is non-single by the ion plating method before the second semiconductor film 5 is formed by the second film forming apparatus 2. The first semiconductor film 4 is formed on the crystal substrate 3. In this way, by forming the first semiconductor film 4 containing the first semiconductor material by the ion plating method, the first semiconductor film 4 is oriented in an order close to that of a single crystal (each crystallite is the same as each other). It can be a highly oriented polycrystalline film (called a single crystal texture or a uniaxial crystal texture film) having an orientation order). By forming the second semiconductor film 5 on such a first semiconductor film 4, it is possible to obtain the second semiconductor film 5 along the highly oriented first semiconductor film 4. Therefore, the second film forming apparatus 2 is compared with a comparative example in which the second semiconductor film 5 is formed on the first semiconductor film 4 to form a film directly on the non-single crystal substrate 3. , A highly oriented second semiconductor film 5 can be obtained. As described above, even if the non-single crystal substrate 3 which is cheaper than the single crystal semiconductor substrate is used, the second semiconductor is formed by forming the first semiconductor film 4 with the first film forming apparatus 1. The film quality of the film 5 can be improved. That is, it is possible to obtain a highly oriented semiconductor film equivalent to the highly oriented semiconductor film obtained by a conventional method of forming a semiconductor film after etching a single crystal semiconductor substrate to remove polishing scratches and carbides. From the above, it is possible to obtain a high-quality semiconductor film while suppressing the cost. Further, the film forming method according to the present embodiment can also obtain the same actions and effects as the film forming system 100.

The first semiconductor film 4 is a polycrystalline alignment film, and the second semiconductor film 5 has an orientation order in the growth direction of the first semiconductor film 4 in the same direction as the growth direction of the first semiconductor film 4. For example, as shown in FIG. 3A, the second semiconductor film 5 formed by the film forming system 100 has the same orientation of the first semiconductor film 4 formed on the non-single crystal substrate 3. Therefore, the orientations are aligned along the first semiconductor film 4. Since the crystallites 5a of the second semiconductor film 5 are aligned in a single direction, it can be treated as a polycrystalline film having almost a single crystal (single orientation) and the same orientation. In the second semiconductor film 5 having such a good film quality, scattering at the grain boundaries can be made as zero as possible, and high carrier mobility can be realized.

Further, as a comparative example, there is a product in which a buffer layer (ZnO layer) for lattice matching is formed on a high-quality silicon or sapphire substrate, but when forming the buffer layer, a buffer layer is simply formed. In addition to this, it is necessary to anneal the buffer layer at a high temperature of, for example, 600 ° C. or higher. Since the film forming temperature in the first film forming apparatus 1 by the ion plating method according to the present embodiment may be about 200 ° C., it is not necessary to provide an annealing apparatus or the like, so that the handling is easy even on the line process. improves.

Further, the first film forming apparatus 1 forms the first semiconductor film 4 thinner than the second semiconductor film 5. That is, since the first semiconductor film 4 has a function of adjusting the orientation of the second semiconductor film 5 formed on the upper surface thereof, the first semiconductor film 4 may be made as thin as possible so as to fulfill the function. As described above, even if the first semiconductor film 4 is thin, the film quality of the second semiconductor film 5 can be sufficiently improved.

Further, the film forming system 100 further includes a negative ion irradiation unit 24 that irradiates the first semiconductor film 4 with negative ions after the first film forming apparatus 1 forms the first semiconductor film 4. There is. By irradiating the first semiconductor film 4 with negative ions by the negative ion irradiation unit 24, the orientation order of the first semiconductor film 4 is further improved, and the atomic vacancy point defects of the first semiconductor film 4 are improved. The density can be reduced. Thereby, the film quality of the second semiconductor film 5 can be further improved.

The present invention is not limited to the above-described embodiment.

For example, in FIG. 1, it is described that the first film forming apparatus 1 and the second film forming apparatus 2 are connected by a line, but the first film forming apparatus 1 and the second film forming apparatus 2 are connected. 2 may be provided in different facilities from each other. That is, the non-single crystal substrate 3 formed by the first film forming apparatus 1 may be transported to another facility and then formed by the second film forming apparatus 2.

Further, the configurations of the film forming apparatus shown in FIGS. 4 to 6 are merely examples, and other configurations may be adopted as long as the main points are not deviated.

Using a single crystal semiconductor substrate instead of a non-single crystal substrate, a first semiconductor film is formed on the single crystal semiconductor substrate by the first film forming apparatus, and a single film is formed by the second forming apparatus. By forming the second semiconductor film on the first semiconductor film on the substrate of the crystalline semiconductor, there is an advantage that the process temperature can be lowered to each stage as compared with the conventional method.

[Example]
Hereinafter, the film forming system according to one embodiment of the present invention will be specifically described based on Examples, but the configuration of the film forming system is not limited to the following Examples.

(Comparative Example 1)
As the film forming system according to Comparative Example 1, a system provided with only a second film forming apparatus was used. A second semiconductor film was directly formed on the non-single crystal substrate by the film forming system according to Comparative Example 1. DC-magnetron sputtering was adopted as the film forming method of the second film forming apparatus. As the second semiconductor material, Al-added ZnO was adopted. The thickness of the second semiconductor film was set to 500 nm. As the non-single crystal substrate, a glass substrate of non-alkali glass (Eagle-XG, Corning Inc.) was used. Various conditions of the second film forming apparatus are shown below.
<Model of the second film forming apparatus (DC-magnetron sputtering)>
ULVAC CS-L
<Film formation conditions>
・ Process gas: Argon gas ・ Pressure: 1 Pa
-Substrate temperature: 200 ° C
・ Electric power: 200W

(Comparative Example 2)
As the film forming system according to Comparative Example 2, a third film forming apparatus for forming a buffer layer on a non-single crystal substrate by a sputtering method and a second film forming apparatus on the upstream side of the second forming apparatus. A device equipped with a device was used. RF-magnetron sputtering was adopted as the film forming method of the third film forming apparatus. The third film forming apparatus adopted Ga-added ZnO as the semiconductor material of the buffer layer. The thickness of the buffer layer was 10 nm. The second film forming apparatus formed a second semiconductor film having a thickness of 490 nm on the buffer layer. Other conditions for film formation by the second film forming apparatus were the same as in Comparative Example 1. Various conditions of the third film forming apparatus are shown below.
<Model of the third film forming apparatus (RF-magnetron sputtering)>
ULVAC CS-L
<Film formation conditions>
・ Process gas: Argon gas ・ Pressure: 1 Pa
-Substrate temperature: 200 ° C
・ Electric power: 200W

(Example)
As the film forming system according to the embodiment, a first film forming apparatus by an ion plating method for forming a first semiconductor layer on a non-single crystal substrate on the upstream side of the second film forming apparatus, and a first film forming apparatus. The one provided with the film forming apparatus of 2 was used. In the first film forming apparatus, Ga-added Zn O was adopted as the semiconductor material of the first semiconductor layer. The thickness of the first semiconductor layer was set to 10 nm. The second film forming apparatus formed a second semiconductor film having a thickness of 490 nm on the buffer layer. Other conditions for film formation by the second film forming apparatus were the same as in Comparative Example 1. Various conditions of the first film forming apparatus are shown below.
<Model of the first film forming apparatus (ion plating method)>
RPD equipment manufactured by Sumitomo Heavy Industries, Ltd. <Film formation conditions>
・ Discharge current 150A
-Total pressure: 0.3Pa (process gas is argon gas and oxygen gas, oxygen ratio is about 7%)

(Observation of cross section)
The cross section of each film was observed with reference to the images of the transmission electron microscope (TEM: Transmission Electron Microscope) of the cross section of the film obtained in Comparative Example 1, Comparative Example 2, and Example. An example of a cross-sectional image is shown in FIG. The upper part of FIG. 7 shows a cross section of the entire semiconductor film, and the lower part of FIG. 7 shows an enlarged cross section of the semiconductor film near the lower end of the second semiconductor film. The alternate long and short dash line in the lower image of FIG. 7 indicates the boundary between the first semiconductor layer or the second semiconductor layer and the non-single crystal substrate. As shown in FIG. 7A, in Comparative Example 1, it is understood that the crystals are not aligned in the vicinity of the non-single crystal substrate 3. As shown in FIG. 7 (b), in Comparative Example 2, the crystals are aligned as compared with Comparative Example 1, but the crystal arrangement is obliquely changed in the crystallites as compared with Example. You can check. As shown in FIG. 7C, it is understood that in the examples, by having the highly oriented first semiconductor film 4, the crystals are more aligned than in each comparative example. As described above, it was observed that the crystals of the second semiconductor film were aligned by forming the first semiconductor film on the non-single crystal substrate as in the examples.

(Measurement by X-ray diffraction)
The films obtained in Comparative Example 1, Comparative Example 2 and Examples were measured by an X-ray diffraction (XRD: X-Ray Diffraction) measurement method. As an X-ray diffraction measuring instrument, a model called "SmatLab manufactured by Rigaku" was used. The measurement results are shown in FIGS. 8 and 9. FIG. 8 shows a reciprocal lattice map obtained by the measurement. The upper part of FIG. 9 is a pole figure showing the distribution of the 0001 component, and the lower part is a graph showing the distribution of the inclination of the 0001 component with respect to the C-axis direction (0 °). The "0001 component" means a plane through which the (0001) vector represented by the (a1, a2, a3, c) vector in the ZnO crystal lattice shown in FIG. 12 passes vertically. ZnO tends to grow in the C-axis direction in the hexagonal Wurtzite structure, and the “C-axis” and the vertical direction of the substrate can be regarded as the same. In FIG. 8, the portion indicated by “P” in the figure expands and does not draw an arc, and the closer to the point, the closer the second semiconductor film is to a single crystal, indicating that it is highly oriented. Further, in FIG. 9, it is shown that the peaks of the 0001 component are concentrated in the C-axis direction (0 °), so that the sharper the peak is drawn in the C-axis direction, the higher the orientation order is closer to that of a single crystal. .. For example, when the orientation is random as shown in FIG. 3 (b), it grows diagonally with respect to the vertical direction of the substrate and therefore has a peak near 66 °, but the same orientation order as shown in FIG. 3 (a). If so, such peaks will not be detected.

As shown in FIG. 8, in Comparative Example 1 and Comparative Example 2, the portion indicated by “P” drew an arc. In comparison with these, in the examples, the portion indicated by “P” had a shape closer to a point than in Comparative Examples 1 and 2. From this, it is understood that the example has a structure closer to a single crystal as compared with Comparative Example 1 and Comparative Example 2. Further, as shown in FIG. 9, in the example, the 0001 components were mostly concentrated in the C-axis direction, and a sharp peak was drawn in the C-axis direction. The half width of the 0001 component was 1.8 °, and most of the 0001 component was present in the range of −0.9 ° to + 0.9 ° from the C-axis direction (0 °). On the other hand, in Comparative Example 1, the peak of the 0001 component was present in a ring shape not only in the C-axis direction but also in the vicinity of other angles (near 66 °). From this, it is understood that the crystal grows diagonally when viewed from the C axis. Further, in Comparative Example 2, the 0001 components were not densely packed in the C-axis direction as compared with the Examples. That is, it is understood that in the examples, a polycrystalline film having the same orientation order close to that of a single crystal was obtained, and in Comparative Example 1 and Comparative Example 2, a randomly oriented polycrystalline film was obtained.

(Electrical characteristics)
The electrical characteristics of the films obtained in Comparative Examples 1, 2 and Examples were measured by Hall effect measurement in a room temperature environment. The measurement results are shown in FIGS. 10 and 11. "N: Carrier density" indicates the carrier density. “Μ _H : Hole mobility” indicates the carrier mobility of the entire bulk. The higher the value, the higher the carrier mobility. "Ρ: resistivity" indicates the resistivity of the film. “Μ _opt : Optical mobility” indicates the carrier movement speed in the grain. The higher the value, the higher the carrier mobility. "Μ _GB : Grain boundary scattering" indicates the degree of scattering at the grain boundaries. Since the relationship "1 / μ _H = 1 / μ _opt + 1 / μ _GB " is established, the hole mobility is determined by intergranular scattering and intragranular movement. “Μ _opt / μ _GB ” indicates the contribution of grain boundary scattering. The closer the value is to 0, the less the scattering at the grain boundaries is.

As shown in FIG. 10, the carrier density N of the examples is higher than the carrier density N of Comparative Example 1 and the carrier density N of Comparative Example 2. This indicates that the effect of the first semiconductor film improves the orientation order, thereby improving the dopant efficiency and increasing the carrier density N. Further, the hole mobility mu _H embodiments, higher than the hole mobility mu _H of the hole mobility mu _H and Comparative Example 2 Comparative Example 1. This indicates that the presence of the first semiconductor film results in the same orientation order and the grain boundary scattering is reduced, so that the hole mobility μ _H is increased. Further, the presence of the first semiconductor film improves the dopant efficiency, increases the carrier density N, reduces the grain boundary scattering, and increases the hole mobility μ _H, so that the resistivity ρ also decreases. The optical mobility μ _opt is almost the same in each comparative example and the example, while the “μ _opt / μ _GB ” indicating the grain boundary scattering contribution is lower in the examples than in each comparative example and is close to 0. It has become. From this, it is understood that since the examples have the same orientation order close to that of a single crystal, there is little scattering at the grain boundaries and high carrier mobility can be realized.

1 ... 1st film forming apparatus, 2 ... 2nd film forming apparatus, 3 ... Non-single crystal substrate, 4 ... 1st semiconductor film, 5 ... 2nd semiconductor film, 24 ... Negative ion irradiation unit, 100 ... Film formation system.

Claims (5)

A film formation system that forms a film on a non-single crystal substrate.
The first film forming apparatus for forming a film by the ion plating method and
A second film forming apparatus for forming a film on the downstream side of the first film forming apparatus is provided.
The first film forming apparatus deposits a first semiconductor film containing the first semiconductor material on the non-single crystal substrate.
The second film forming apparatus is a film forming system for forming a second semiconductor film containing a second semiconductor material on the first semiconductor film on the non-single crystal substrate. The film forming system according to claim 1, wherein the first film forming apparatus is a film forming device for forming the first semiconductor film thinner than the second semiconductor film. The first semiconductor film is a polycrystalline alignment film, and is
The film forming system according to claim 1 or 2, wherein the second semiconductor film has an orientation order in the same direction as the growth direction of the first semiconductor film. Any one of claims 1 to 3, further comprising a negative ion irradiation unit that irradiates the first semiconductor film with negative ions after the first film forming apparatus has formed the first semiconductor film. The film formation system described in. This is a film forming method for forming a film on a non-single crystal substrate.
The first film formation step of forming a film by the ion plating method and
A second film forming step for forming a film after the first film forming step is provided.
In the first film forming step, a first semiconductor film containing the first semiconductor material is formed on the non-single crystal substrate.
In the second film forming step, a film forming method for forming a second semiconductor film containing a second semiconductor material on the first semiconductor film on the non-single crystal substrate.