JP2011181602A - Method and device for manufacturing semiconductor film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for manufacturing a semiconductor film by which a large area of semiconductor film with superior quality is stably and easily manufactured. <P>SOLUTION: The method includes a step of heating the semiconductor film deposited on a cathode electrode by heating the cathode electrode, a step of measuring multiple times, the amount of desorption hydrogen atoms desorbed from the heated semiconductor film in response to a temperature of the cathode electrode, a step of analyzing the measurement results on the amount of desorption hydrogen atoms, reflecting the film quality of the semiconductor film, and acquiring film quality information to be an index to adjust a film deposition condition, and a step of resetting the film deposition condition of the semiconductor film to be the second film deposition condition based on the film quality information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor film manufacturing method and a semiconductor film manufacturing apparatus.

  Conventionally, thin film solar cells employ a tandem structure in which a plurality of photoelectric conversion layers (semiconductor layers) made of materials with different band gaps are stacked on a light-transmitting insulating substrate in order to effectively use the solar spectrum widely. Yes. In particular, in the case of a silicon-based thin-film solar cell, an amorphous silicon cell and a microcrystalline silicon cell are often laminated as a semiconductor layer. Here, each photoelectric conversion layer (semiconductor layer) has a structure in which a p-type film, an i-type film, and an n-type film are stacked. The i-type film is a power generation layer, and the p-type film and the n-type film are built-in electric fields. It is a layer for forming.

Such silicon-based thin films are often formed by plasma enhanced chemical vapor deposition (plasma CVD) using silane gas (SiH ₄ ) and hydrogen gas (H ₂ ) as raw materials, and the film quality is in a plasma state ( It is known that it strongly depends on the electron temperature, plasma potential, and plasma density. In addition, the plasma state includes various film forming parameters (raw material gas flow ratio [H ₂ / SiH ₄ ], applied power, power supply frequency, film forming pressure, etc.) and film forming chamber state (cathode electrode surface state, residual deposit). Etc.).

  In particular, in an amorphous silicon cell, it is preferable to apply an amorphous silicon film appropriately containing hydrogen as the amorphous silicon film of the power generation layer. This is because hydrogen terminates dangling bonds in the film and reduces the defect density. When film formation is performed by the plasma CVD method, hydrogen atoms are taken into the film during film deposition to terminate dangling bonds. However, it is necessary to optimize the film forming conditions in order to contain the necessary and sufficient hydrogen in the film. If an amorphous silicon film with many defects is applied to the power generation layer of a solar cell, carriers (electrons and holes) generated by light irradiation are trapped in the defect, resulting in loss of power generation current and high photoelectric conversion efficiency. It becomes difficult to get.

  In such a plasma CVD apparatus for forming a semiconductor film such as an amorphous silicon film, improvement of in-plane uniformity of film quality has become an important issue as the substrate area increases. When the plasma CVD apparatus is increased in size as the substrate area is increased, the maximum surface dimension of the high-frequency electrode is increased, so that the influence of standing waves generated on the electrode is increased. When the influence of this standing wave is increased, the in-plane uniformity of plasma is deteriorated, which causes deterioration of film quality and in-plane uniformity of film quality. In addition, if the plasma CVD apparatus is continuously used, the actual value actually applied to the plasma differs from the set value of the RF power due to the surface roughness of the cathode electrode and the residue in the film forming chamber, It may cause deterioration of film quality and deterioration of film quality uniformity in a plane. As a result, yield decreases and photoelectric conversion efficiency decreases.

  In order to suppress such a decrease in yield and a decrease in photoelectric conversion efficiency, the quality of the film formed is evaluated, and the film forming parameters are adjusted and the film forming chamber is cleaned based on this result. As a method for evaluating the film quality, for example, there is a method in which the film-formed substrate is transferred to a stage of another vacuum vessel and heated there to determine the film quality by the temperature rise temperature dependency of the hydrogen atom release amount (for example, , See Patent Document 1).

JP 2002-246622 A

  However, according to the above-described conventional technology, there is a problem that a large vacuum container that only accommodates a large substrate is required, and it takes time and effort to transfer. In addition, measurement of in-plane distribution is not taken into account, and a method for resetting the film forming conditions in order to improve the film quality from the obtained results is not disclosed.

  The present invention has been made in view of the above, and an object of the present invention is to provide a semiconductor film manufacturing method and a semiconductor film manufacturing apparatus capable of stably and easily manufacturing a high-quality semiconductor film having a large area. And

  In order to solve the above-described problems and achieve the object, a method for manufacturing a semiconductor film according to the present invention provides a cathode electrode in a state where a source gas is supplied into a film forming chamber in which a substrate to be processed is held on the anode electrode. A semiconductor film is formed by supplying electric power to generate plasma between the cathode electrode and the anode electrode, decomposing the source gas by the plasma and depositing it on the film surface of the substrate to be processed. A method of manufacturing a semiconductor film, comprising: supplying a power to the cathode electrode while supplying the source gas into the film forming chamber under a first film forming condition to generate plasma between the cathode electrode and the anode electrode. A first step of forming the semiconductor film on the cathode electrode and generating a semiconductor film deposited on the cathode electrode by heating the cathode electrode; A third step of measuring the number of desorbed hydrogen atoms desorbed from the heated semiconductor film a plurality of times according to the temperature of the cathode electrode, and analyzing the measurement result of the desorbed hydrogen atom amount to determine the film quality of the semiconductor film A fourth step of acquiring film quality information to be reflected and an index for adjusting the film forming conditions; and a fifth step of resetting the film forming conditions of the semiconductor film to the second film forming conditions based on the film quality information And a sixth step of holding the substrate to be processed on the anode electrode, supplying power to the cathode electrode while supplying a raw material gas into the deposition chamber under the second deposition condition, and A seventh step of generating plasma between the electrode and the anode electrode to form the semiconductor film on the film-forming surface of the substrate to be processed.

  According to the present invention, a high-quality semiconductor film having a large area and excellent in-plane uniformity of the film quality is stably produced with a high yield by measuring the film quality simply and quickly and resetting the film forming conditions. There is an effect that can be done.

FIG. 1 is a schematic diagram for explaining a configuration of a plasma CVD apparatus which is a semiconductor film manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is a plan view showing a planar structure of the divided cathode electrode of the plasma CVD apparatus according to the first embodiment of the present invention. FIG. 3 is a schematic diagram for explaining details of a means for cooling the cathode electrode in the plasma CVD apparatus according to the first embodiment of the present invention. FIG. 4 is a flowchart for explaining the amorphous silicon film forming method according to the first embodiment of the present invention. FIG. 5 is a schematic diagram showing a method of heating the cathode electrode from the back side with a lamp in the plasma CVD apparatus according to the first embodiment of the present invention. FIG. 6 is a schematic diagram showing a method of heating the cathode electrode with a resistance wire heater in the plasma CVD apparatus according to the first embodiment of the present invention. FIG. 7 is a characteristic diagram showing the relationship between the heating temperature of the cathode electrode and the amount of desorbed hydrogen atoms from the i-type amorphous silicon film when the i-type amorphous silicon film formed by the conventional film-forming method is heated. is there. FIG. 8 is a characteristic diagram showing the relationship between the number of depositions of an i-type amorphous silicon film deposited by the conventional deposition method and the half-value width (° C.) in the desorbed hydrogen atomic weight profile. FIG. 9 shows the relationship between the half-value width (° C.) of the heating temperature of the cathode electrode and the RF power (W) during film formation in the desorption hydrogen atomic weight profile of the i-type amorphous silicon film formed by the conventional film formation method. FIG. FIG. 10 shows the half-value width (° C.) in the desorbed hydrogen atomic weight profile of the i-type amorphous silicon film manufactured by resetting the RF power under the film forming conditions by the method for forming the amorphous silicon film according to the first embodiment. FIG. 6 is a characteristic diagram showing the relationship between the number of times of film formation. FIG. 11 is a plan view showing a planar structure of the cathode electrode of the plasma CVD apparatus according to the second embodiment of the present invention. FIG. 12 is a characteristic diagram showing the relationship between the number of depositions of the i-type amorphous silicon film deposited by the deposition method according to the second embodiment of the present invention and the half-value width (° C.) in the desorbed hydrogen atomic weight profile. is there.

  EMBODIMENT OF THE INVENTION Below, embodiment of the manufacturing method of the thin film silicon solar cell concerning this invention and the manufacturing apparatus of a thin film silicon solar cell is described in detail based on drawing. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram for explaining a configuration of a plasma CVD apparatus which is a semiconductor film manufacturing apparatus according to a first embodiment of the present invention. As shown in FIG. 1, a translucent insulating substrate 2 that is a substrate to be processed is placed on an anode electrode 1 that also serves as a holding member (substrate stage) for a substrate to be processed inside a film forming chamber 18 having a substantially rectangular parallelepiped shape. Is held. The anode electrode 1 is grounded. A translucent insulating substrate 2 is held on the anode electrode 1 so that the film-forming surface is horizontal and upward.

  Further, as shown in FIG. 1, a cathode electrode 4 is provided on the upper surface of the film forming chamber 18 at a position facing the anode electrode 1. As shown in FIG. 2, the cathode electrode 4 has a plurality of small-area cathode electrodes 41, cathode electrodes 42, and cathode electrodes 43 obtained by dividing the in-plane of the electrode into four zones of region (a) to region (d). The cathode electrode 44 is divided into four regions. FIG. 2 is a plan view showing the planar structure of the divided cathode electrode 4 as viewed from the anode electrode 1 side.

  A power source 5 is connected to the cathode electrode 4. When high frequency power (RF power) is applied from the power source 5 to the cathode electrode 4, high frequency power is applied between the cathode electrode 4 and the anode electrode 1, and the cathode electrode 4 and the translucent insulating substrate 2 (anode electrode). Plasma 11 is generated between 1) and 1). The high frequency power (RF power) applied from the power source 5 to the cathode electrode 4 is divided into four by the distributor 6 and further matched via the power monitor 71, power monitor 72, power monitor 73, and power monitor 74, respectively. The applied power 151, applied power 152, applied power 153, and applied power 154 through the device 81, the matching device 82, the matching device 83, and the matching device 84 are the cathode electrode 41, the cathode electrode 42, the cathode electrode 43, and the cathode electrode 44, respectively. To be applied.

  FIG. 3 is a schematic diagram for explaining details of means for cooling the cathode electrode 4 in the plasma CVD apparatus according to the first embodiment. A cooling water pipe 141, a cooling water pipe 142, a cooling water pipe 143, and a cooling water pipe 144 for flowing cooling water to cool the cathode electrode 4 above the cathode electrode 4 are a cathode electrode 41 and a cathode electrode 42, respectively. The cathode electrode 43 and the cathode electrode 44 are disposed in correspondence with each other. The cooling water pipe 141, the cooling water pipe 142, the cooling water pipe 143, and the cooling water pipe 144 include a cooling water control device 131, a cooling water control device 132, and a cooling water control device 133 that control the amount of cooling water that flows to each cooling pipe. The cooling water control device 134 is connected.

  Further, the cathode electrode 4 includes a temperature control device 121, a temperature control device 122, a temperature control device 123, and a temperature control device 124 for controlling the temperature of the cathode electrode 4, respectively, a cathode electrode 41, a cathode electrode 42, and a cathode electrode. 43 and the cathode electrode 44 are connected. The temperature control devices 121, 122, 123, 124 measure the temperatures of the corresponding cathode electrodes 41, 42, 43, 44, respectively, and provide control instruction information for the cooling water amount based on the measured temperatures. , 133 and 134. The cooling water control devices 131, 132, 133, 134 control the amount of cooling water flowing in the cooling water pipes 141, 142, 143, 144 based on the cooling water amount control instruction information, and each cathode electrode 41, 42, 43, 44 temperature is controlled.

A gas supply pipe 3 for feeding a raw material gas into the film forming chamber 18 is connected to the lower portion of the film forming chamber 18 through a gas supply port 3a. The gas supply pipe 3 is connected to a gas supply source 3b such as a gas cylinder. By the raw material gas introducing means constituted by these, silane gas (SiH ₄ ) and hydrogen gas (H ₂ ) can be supplied from the gas supply source 3 b through the gas supply pipe 3 to the film forming chamber 18.

  The source gas introduced from the gas supply pipe 3 into the film forming chamber 18 is decomposed by the plasma 11 to generate a film forming precursor, which is deposited and deposited on the translucent insulating substrate 2 and the cathode electrode 4. A silicon film 16 is formed.

  Further, a gas discharge pipe 9 for discharging the gas in the film forming chamber 18 is connected to the lower part of the film forming chamber 18. An exhaust device 17 is connected to the gas exhaust pipe 9, and the gas in the film forming chamber 18 can be exhausted and evacuated using an exhaust means constituted by the gas exhaust pipe 9 and the exhaust device 17. It is said that. A mass analyzer 10 is connected in the middle of the gas discharge pipe 9 so that the amount of hydrogen atoms discharged from the film forming chamber 18 can be measured.

  Although the gas supply port 3a and the cathode electrode 4 are separately arranged here, a shower head structure in which a hole through which the gas can pass is provided in the cathode electrode 4 and the cathode electrode 4 itself is the gas supply port. The source gas may be supplied from the cathode electrode 4 to the film forming chamber 18. Moreover, you may provide insulators, such as an alumina, in the clearance gap between each cathode electrode 4 so that a deposit may not enter. Here, the number of divisions of the cathode electrode 4 is four, but the number of divisions is not particularly limited and may not be divided.

  Next, referring to FIG. 4 for the film forming process of the i-type amorphous silicon film that becomes the power generation layer in the photoelectric conversion layer (semiconductor layer) of the silicon-based thin film solar cell using the plasma CVD apparatus according to the first embodiment. While explaining. FIG. 4 is a flowchart for explaining the amorphous silicon film forming method according to the first embodiment.

  In order to perform an i-type amorphous silicon film forming process, first, the deposited film in the film forming chamber 18 is removed, a glass substrate is held on the anode electrode 1 in the film forming chamber 18 as a dummy substrate, and then the exhaust gas is exhausted. The apparatus 17 evacuates the film forming chamber 18 through the gas discharge pipe 9 to bring the film forming chamber 18 into a vacuum state. Next, a raw material gas such as silane gas is introduced into the film forming chamber 18 from the gas supply source 3 b through the gas supply pipe 3.

  When a high frequency power is applied to the cathode electrode 4 by the power source 5 in the state as described above to generate an electric field between the cathode electrode 4 and the anode electrode 1, a plasma generation region, that is, the translucent insulating substrate 2 and In a region facing the cathode electrode 4, the source gas is excited to generate plasma 11, and the source gas is decomposed by the plasma 11. Thereby, a film-forming precursor is generated, and this film-forming precursor is deposited on the translucent insulating substrate 2 and the cathode electrode 4 to form an i-type amorphous silicon film (step S10).

  The film forming conditions for the i-type amorphous silicon film are the predetermined first film forming conditions. For example, the flow rate ratio of hydrogen gas to silane gas is 10 to 1, the pressure is 2.5 Torr, and the RF to each cathode electrode 4 is RF. The power is set to 10W. Here, a dummy substrate is used as the film formation substrate. However, the light-transmitting insulating substrate 2 as a product may be used, and the substrate may not be inserted. However, the use of a dummy substrate has the advantage that the product can be processed after the film quality is optimized. Further, the use of the translucent insulating substrate 2 as a product has the advantage of reducing dummy substrates and improving the throughput of the apparatus. Further, if a dummy substrate is not used, there is an advantage that leads to reduction of the substrate.

  After the i-type amorphous silicon film is formed, when the dummy substrate is carried out of the film forming chamber 18, the i-type amorphous silicon film 16 remains on the cathode electrode 4 in the film forming chamber 18.

  Next, the i-type amorphous silicon film formed on the cathode electrode 4 is heated (step S20). Heating is performed by heating the cathode electrode 4. The exhaust device 17 evacuates the film forming chamber 18 through the gas discharge pipe 9, introduces argon (Ar) gas into the film forming chamber 18 from the gas supply source 3 b through the gas supply pipe 3, High frequency power is applied to each cathode electrode 4 to generate plasma between the anode electrode 1 and the cathode electrode 4. The plasma generation conditions here are set to Ar: 1000 sccm, RF power applied to each cathode electrode 4: 250 W, pressure 8 Torr, temperature of anode electrode 1: 200 ° C.

  The i-type amorphous silicon film formed on the cathode electrode 4 and the cathode electrodes 41, 42, 43, and 44 receive heat from the plasma, and the i-type amorphous silicon film is heated. Here, the temperature of each cathode electrode 41, 42, 43, 44 is measured by the temperature control devices 121, 122, 123, 124, and the control instruction information of the cooling water amount is sent to the cooling water control devices 131, 132 based on the measured temperature. , 133, 134. The cooling water control devices 131, 132, 133, 134 control the amount of cooling water flowing in the cooling water pipes 141, 142, 143, 144 based on the cooling water amount control instruction information, and each cathode electrode 41, 42, 43, 44 temperature is controlled.

  By such control, for example, the temperature of the cathode electrode 4 rises to 450 ° C. after 500 seconds at a constant temperature increase speed. Due to this temperature rise, hydrogen atoms are desorbed from the i-type amorphous silicon film formed on the cathode electrode 4 and discharged from the film forming chamber 18 through the gas discharge pipe 9 together with Ar gas or the like. Then, by measuring the amount of hydrogen atoms in the discharged gas with the mass analyzer 10, the amount of hydrogen desorbed from the heated i-type amorphous silicon film (the amount of desorbed hydrogen atoms) is obtained from the cathode electrode 4. It measures according to temperature (step S30). Here, all the cathode electrodes 41, 42, 43, and 44 are controlled to have a constant temperature rise, but the cathode electrode 4 is selected so that the region of the i-type amorphous silicon film whose film quality is to be examined is heated. You may do it.

  Here, the temperature of the i-type amorphous silicon film formed on the cathode electrode 4 is increased by heat input from the plasma. As a heating mechanism for the i-type amorphous silicon film, for example, as shown in FIG. For example, a method of heating by the lamp 101 from the back side of 4 or a method of heating by placing a resistance wire heater 102 near the cathode electrode 4 as shown in FIG. 6 may be used. Also in this case, it is preferable to have a mechanism for independently heating a plurality of regions in the cathode electrode 4 because the region in the i-type amorphous silicon film to be examined can be selected. FIG. 5 is a schematic diagram showing a method of heating the cathode electrode 4 from the back side with the lamp 101. FIG. 6 is a schematic diagram showing a method of heating the cathode electrode 4 with the resistance wire heater 102.

  Next, the measurement result of the amount of desorbed hydrogen atoms is analyzed, and film quality information serving as an index for adjusting the film forming conditions is obtained by reflecting the film quality of the formed i-type amorphous silicon film (step S40). . As this film quality information, for example, the half-value width (° C.) of the heating temperature of the cathode electrode 4 in the desorbed hydrogen atom amount profile obtained from the relationship between the heating temperature of the cathode electrode 4 and the amount of desorbed hydrogen atoms (hereinafter simply referred to as the half-value width). In some cases). Then, based on the obtained film quality information, the film forming condition of the i-type amorphous silicon film is reset to the second film forming condition (step S50). That is, the first film forming condition set in advance and the film quality information are compared, and the film forming condition of the i-type amorphous silicon film is reset to the second film forming condition. The analysis of the measurement result of the amount of desorbed hydrogen atoms and the resetting of the film forming conditions for the i-type amorphous silicon film are performed, for example, by a control unit (not shown), and the second film forming conditions are transmitted to each unit of the apparatus for control. May be.

  Next, the inside of the film forming chamber 18 is cleaned as necessary, and the translucent insulating substrate 2 serving as the substrate to be processed is held on the anode electrode 1. Then, based on the reset second film forming conditions, power is supplied to the cathode electrode 4 while supplying the raw material gas into the film forming chamber 18 to generate plasma between the cathode electrode 4 and the anode electrode 1. Then, an i-type amorphous silicon film is formed on the film-forming surface of the translucent insulating substrate 2 (step S60).

  In the film forming method according to the first embodiment described above, the amount of desorbed hydrogen atoms desorbed from the formed i-type amorphous silicon film is measured, and the film quality information serving as an index for adjusting the film forming conditions is obtained. Obtained from the measurement result of the hydrogen atomic weight. Then, the film forming conditions are reset based on the film quality information, and the subsequent film forming process is performed. The film quality of the i-type amorphous silicon film to be formed can be optimized.

FIG. 7 shows an example of a profile of the amount of desorbed hydrogen atoms measured in a conventional method for forming an i-type amorphous silicon film, that is, film formation without resetting the film formation conditions. FIG. 7 is a characteristic diagram showing the relationship between the heating temperature of the cathode electrode 4 and the amount of desorbed hydrogen atoms from the i-type amorphous silicon film when the i-type amorphous silicon film formed by the conventional film-forming method is heated. It is. Here, after the cathode electrode 4 is replaced in the plasma CVD apparatus according to the first embodiment, first, dummy film formation is performed under a predetermined film formation condition of an i-type amorphous silicon film, and then deposition in the film formation chamber 18 is performed. Dry cleaning with nitrogen trifluoride (NF ₃ ) gas for removing substances was performed, and these treatments were performed as one cycle, and this cycle was performed five times. Thereafter, the i-type amorphous silicon film is deposited 600 times, and desorption from the i-type amorphous silicon film when the first film is formed and the i-type amorphous silicon film when the 600th film is formed. The hydrogen atomic weight was measured.

It should be noted that after the i-type amorphous silicon film is formed, a dry cleaning process is employed each time the film in the film forming chamber 18 is removed by nitrogen trifluoride (NF ₃ ). However, in actual operation, dry cleaning is not necessarily required every time, and dry cleaning may be performed only before the formation of the amorphous silicon film for examining the desorption hydrogen atomic weight profile. Further, the method for removing the film in the film forming chamber 18 may be wet etching using a solution.

  From FIG. 7, the half-value width (° C.) of the heating temperature of the cathode electrode 4 in the desorption hydrogen atomic weight profile of the i-type amorphous silicon film formed at the 600th time is larger than that of the i-type amorphous silicon film formed at the first time. It can be seen that the film quality has changed. FIG. 8 is a characteristic diagram showing the relationship between the number of depositions of an i-type amorphous silicon film deposited by the conventional deposition method and the half-value width (° C.) in the desorbed hydrogen atomic weight profile. In FIG. 8, the horizontal axis represents the number of times the i-type amorphous silicon film is formed, and the vertical axis represents the half-value width (° C.) in the desorbed hydrogen atom amount profile desorbed from the i-type amorphous silicon film at that time. FIG. 8 shows that the full width at half maximum (° C.) increases with an increase in the number of times of film formation, and that the half width (° C.) depends on the number of times of film formation.

  Further, in order to investigate the characteristics of the solar cell when the i-type amorphous silicon film formed by 600 times of film formation as described above is applied to the power generation layer of the photoelectric conversion layer, a thin-film solar cell is as follows. It was prepared. First, a transparent conductive film having irregularities formed on the surface was formed as a first electrode on a translucent insulating substrate. As the translucent insulating substrate, a material having a high transmittance is usually used. For example, a glass substrate having a small absorption from the visible region to the near infrared region is used. As the glass substrate, an alkali-free glass substrate with low absorption, an inexpensive blue plate glass substrate, or the like is used. Here, a non-alkali glass substrate was used as the light-transmitting insulating substrate.

As the transparent conductive film, aluminum (Al) was used as a dopant for the crystallized zinc oxide (ZnO) film. The dopant may be at least one element selected from Al, Ga, In, B, Y, Si, Zr, and Ti. The transparent conductive film may be a transparent conductive film having a light and high transparency, for example _{SnO 2, In 2 O 3,} ZnO, CdO, CdIn 2 O 4, CdSnO 3, MgIn 2 O 4, CdGa Crystallized or amorphous film of ₂ O ₄ , GaInO ₃ , InGaZnO ₄ , Cd ₂ Sb ₂ O ₇ , Cd ₂ GeO ₄ , CuAlO ₂ , CuGaO ₂ , SrCu ₂ O ₂ , TiO ₂ , Al ₂ O ₃ But you can. Moreover, the transparent conductive film comprised by laminating | stacking these films | membranes may be sufficient. Further, as a dopant for these films, at least one element selected from Al, Ga, In, B, Y, Si, Zr, and Ti may be used.

  A DC sputtering method was used for forming the transparent conductive film. In addition to this, for example, a physical method such as a vacuum deposition method or an ion plating method, or a chemical method such as a spray method, a dip method, or a CVD method can be used for forming the transparent conductive film. The unevenness of the surface of the transparent conductive film is obtained by immersing the translucent insulating substrate in an aqueous solution of hydrochloric acid 0.3% by weight and a liquid temperature of 30 ° C. for 90 seconds, followed by washing with pure water for 1 minute or more and drying. Formed.

  Next, a photoelectric conversion layer was formed on the transparent conductive film. The photoelectric conversion layer was formed using the plasma CVD apparatus described in Embodiment 1 by a conventional i-type amorphous silicon film forming method without resetting the film forming conditions. A silicon film having a pin junction was formed as a photoelectric conversion layer. That is, a p-type amorphous silicon carbide film (a-SiC film), an i-type amorphous silicon carbide film (a-SiC film), an i-type amorphous silicon film (a-Si film), n from the transparent conductive film side as a photoelectric conversion layer A type microcrystalline silicon film was formed. Note that the photoelectric conversion layer may have a pn junction. Further, a silicon-based semiconductor film such as amorphous silicon germanium or microcrystalline silicon germanium may be used for each layer of the photoelectric conversion layer. Further, the photoelectric conversion layer may have a tandem structure in which pin junction structures are stacked in two stages, or a triple structure in which pin structures are stacked in three stages.

Next, a back electrode layer was formed on the photoelectric conversion layer. As the back electrode layer, a silver (Ag) film having a thickness of about 200 nm, which is a conductive film that reflects light, was used. In addition to the silver (Ag) film, an aluminum (Al) film having a relatively low cost and high light reflectance may be used as the back electrode layer. Further, zinc oxide (ZnO) was inserted between the photoelectric conversion layer and the back electrode layer in order to prevent metal diffusion from the back electrode layer to the photoelectric conversion layer. In addition to zinc oxide (ZnO), a transparent conductive film such as indium tin oxide (ITO: Indium Tin Oxide) or tin oxide (SnO ₂ ) may be inserted between the photoelectric conversion layer and the back electrode layer. . As described above, 600 thin-film solar cells (conventional example) were produced.

  Next, the characteristics of the conventional thin-film solar cell produced as described above were evaluated. Table 1 shows the characteristic values of the thin-film solar cells. In Table 1, “NO.” Is the number of the thin-film solar cell given in the order of production of the i-type amorphous silicon film of the photoelectric conversion layer, and “NO. 1” is the first formation of the i-type amorphous silicon film. “NO. 200” indicates the thin film solar cell in which the i-type amorphous silicon film was formed for the 200th time.

  As can be seen from Table 1, the photoelectric conversion efficiency deteriorates as the number of i-type amorphous silicon films is increased. This is thought to be due to the deterioration of the film quality of the i-type amorphous silicon film, and an increase in the half-value width (° C.) of the heating temperature of the cathode electrode 4 in the desorbed hydrogen atomic weight profile desorbed from the i-type amorphous silicon film. (FIG. 8). That is, it can be seen that the half width (° C.) of the heating temperature of the cathode electrode 4 in the desorbed hydrogen atomic weight profile is an index of the film quality of the i-type amorphous silicon film.

  Next, a case where an i-type amorphous silicon film is formed by the amorphous silicon film forming method according to the first embodiment described above will be described. The i-type amorphous silicon film was formed 600 times by the amorphous silicon film forming method according to the first embodiment. After the 100th, 200th, 300th, 400th, and 500th film formation, the desorbed hydrogen atomic weight profile was examined. Then, the measurement result of the desorbed hydrogen atom amount is analyzed to reflect the film quality of the formed i-type amorphous silicon film, and as film quality information serving as an index for adjusting the film forming conditions, A half-value width (° C.) of the heating temperature of the cathode electrode 4 was obtained.

  Next, the RF power of the i-type amorphous silicon film forming conditions was reset so that the half-value width (° C.) was 20 ° C. ± 10 ° C., and the reset RF power was reset from the next film forming. Conditions were used. Then, 600 thin-film solar cells (examples) were produced in the same manner as the above-described conventional thin-film solar cells except that the RF power was reset.

  FIG. 9 shows the relationship between the half-value width (° C.) of the heating temperature of the cathode electrode 4 and the RF power (W) during film formation in the desorption hydrogen atomic weight profile of the i-type amorphous silicon film formed by the conventional film formation method. It is a characteristic view which shows a relationship. As shown in FIG. 9, the full width at half maximum (° C.) can be changed by changing the set value of the RF power in the film forming conditions of the i-type amorphous silicon film. Based on the relationship between the RF power and the amount of change in the half-value width, the set value of the RF power is determined in order to obtain the target half-value width (° C.). As shown in FIG. 8, the full width at half maximum (° C.) increased with the increase in the number of times the i-type amorphous silicon film was formed. Therefore, the RF power (W) was reset in the direction of decreasing. The change in the half-value width (° C.) is caused by the surface roughness of the cathode electrode 4 or the residual deposits in the film forming chamber 18 and the like, and the state in the film forming chamber 18 changes. It is thought to arise from the change.

  Here, the full width at half maximum (° C.) increases with an increase in the number of times the i-type amorphous silicon film is formed, but depending on the film formation conditions and the gas used, it may decrease with an increase in the number of times the film is formed. In that case, the RF power (W) may be set to increase. Here, the half-value width (° C.) of the heating temperature of the cathode electrode 4 in the desorbed hydrogen atomic weight profile was used as an index of the film quality of the i-type amorphous silicon film, but the half-value width (° C.) is not necessarily required. The rising temperature, falling temperature, total amount of hydrogen atoms, etc. of the hydrogen separation amount profile may be used as an index.

  FIG. 10 shows the half-value width (° C.) in the desorbed hydrogen atomic weight profile of the i-type amorphous silicon film manufactured by resetting the RF power under the film forming conditions by the method for forming the amorphous silicon film according to the first embodiment. FIG. 6 is a characteristic diagram showing a relationship between the number of times an i-type amorphous silicon film is formed. In FIG. 10, the horizontal axis represents the number of times of i-type amorphous silicon film deposition, and the vertical axis represents the half-value width (° C.) of the heating temperature of the cathode electrode 4 in the desorbed hydrogen atomic weight profile. By resetting the RF power, the half-value width could be controlled to (° C.) 20 ° C. ± 10 C as shown in FIG.

  Table 2 shows the characteristic values of the thin-film solar cells manufactured using these i-type amorphous silicon films as the power generation layer. In Table 2, “NO.” Is the number of the thin-film solar battery cell attached in the production order of the i-type amorphous silicon film of the photoelectric conversion layer, and “NO. 1” is the first formation of the i-type amorphous silicon film. “NO. 200” indicates the thin film solar cell in which the i-type amorphous silicon film was formed for the 200th time.

  As can be seen from Table 2, the photoelectric conversion efficiency does not deteriorate even when the number of times of forming the i-type amorphous silicon film (NO.) Increases. No. 1 thin film solar cell. Almost the same photoelectric conversion efficiency was obtained in 600 thin film solar cells. This is considered to be due to the formation of the i-type amorphous silicon film while preventing the deterioration of the film quality by resetting the RF power under the film forming conditions. It corresponds. That is, by performing the film formation by resetting the RF power under the film forming conditions using the half width (° C.) in the desorbed hydrogen atomic weight profile as an index of the film quality of the i-type amorphous silicon film, the photoelectric conversion efficiency is improved. Thin-film solar cells can be stably produced regardless of the number of i-type amorphous silicon films.

  In the above description, the resetting of the RF power in the film forming conditions is set to the same setting value for the cathode electrode 41 to the cathode electrode 44. However, the resetting of the RF power can be made different for the cathode electrode 41 to the cathode electrode 44. It is.

  In the above description, as a method for preventing the deterioration of the film quality of the i-type amorphous silicon film, the RF power is reset among the film forming conditions of the i-type amorphous silicon film. However, the present invention is not limited to this. The targets for resetting the film forming conditions are the temperature of the light-transmitting insulating substrate 2 when forming the i-type amorphous silicon film, the distance between the cathode electrode 4 and the light-transmitting insulating substrate 2, and the source gas during film forming The flow rate, pressure, deposit (cleaning) of the cathode electrode 4 and the side wall in the film forming chamber 18, replacement of the cathode electrode 4, and the like may be used.

  As described above, in the first embodiment, the amount of desorbed hydrogen atoms released from the formed i-type amorphous silicon film is measured, and the film quality information serving as an index for adjusting the film forming conditions is used as the desorbed hydrogen. An i-type amorphous silicon film to be formed later by measuring the film quality simply and quickly by obtaining the atomic weight measurement result, and adjusting the film forming conditions and cleaning the film forming chamber from the result. The film quality can be optimized and the in-plane uniformity of the film quality can be improved. Thereby, it is possible to stably form a large-area high-quality i-type amorphous silicon film excellent in film quality. In addition, it is not necessary to prepare and transfer a large vacuum container that can accommodate a large substrate separately from the film forming apparatus as in the method of Patent Document 1, which is excellent in terms of cost and workability. .

  Therefore, according to the first embodiment, it is possible to stably produce a high-quality i-type amorphous silicon film having a large area and excellent quality with a high yield without reducing the productivity as compared with the conventional method. It is. Then, by using this i-type amorphous silicon film for the power generation layer of the photoelectric conversion layer, a thin film solar cell excellent in photoelectric conversion efficiency can be obtained.

  In the above description, the case where an i-type amorphous silicon film is formed has been described as an example. However, in the present invention, the semiconductor film to be formed is an amorphous silicon carbide film, an amorphous silicon oxide film, an amorphous silicon germanium film, a fine film. A crystalline silicon film, a microcrystalline silicon carbide film, a microcrystalline silicon oxide film, or a microcrystalline silicon germanium may be used. Even in this case, by performing the same process as described above, it is possible to prevent the deterioration of the film quality and form a high-quality semiconductor film regardless of the number of times of film formation. And the thin film solar cell excellent in photoelectric conversion efficiency can be obtained by using this semiconductor film for the electric power generation layer of a photoelectric converting layer.

Embodiment 2. FIG.
FIG. 11 is a plan view showing a planar structure of the cathode electrode 40 of the plasma CVD apparatus according to the second embodiment. The plasma CVD apparatus according to the second embodiment is different from the plasma CVD apparatus according to the first embodiment in that a cathode electrode 40 described below is provided in place of the cathode electrode 4, and the rest is basically implemented. Since it has the same configuration as the plasma CVD apparatus according to Embodiment 1, it will be described with reference to FIG.

  As shown in FIG. 11, the cathode electrode 40 according to the second exemplary embodiment includes a plurality of small area cathodes obtained by dividing the in-plane of a 1000 mm square electrode into eight zones of region (a) to region (h). The electrodes 401 to 408 are arranged in one plane, and a multi-point power feeding system that can independently supply RF power to the cathode electrodes 401 to 408 is adopted. The cathode electrodes 401 to 408 are connected to a distributor and a power source through a matching unit and a power monitor, respectively, as in the case of the first embodiment.

  In addition, as a configuration corresponding to the cathode electrodes 401 to 408, individual temperature control devices corresponding to the cathode electrodes 401 to 408 are individually corresponded as temperature control devices, and individually corresponded to the cathode electrodes 401 to 408 as cooling water pipes. The cooling water piping is provided with individual cooling water control devices corresponding to the cathode electrodes 401 to 408 as the cooling water control devices.

  Next, an i-type amorphous silicon film forming process by the plasma CVD apparatus according to the second embodiment will be described. First, the deposited film in the film forming chamber 18 is removed and a 950 mm square glass substrate is held on the anode electrode 1 in the film forming chamber 18 as a dummy substrate, and then manufactured by the exhaust device 17 through the gas discharge pipe 9. The film chamber 18 is evacuated, and the film forming chamber 18 is evacuated. Next, a raw material gas such as silane gas is introduced into the film forming chamber 18 from the gas supply source 3 b through the gas supply pipe 3.

  When a high frequency power is applied to the cathode electrode 40 by the power source 5 in the above-described state to generate an electric field between the cathode electrode 40 and the anode electrode 1, a plasma generation region, that is, the translucent insulating substrate 2 and In the region facing the cathode electrode 40, the source gas is excited to generate plasma 11, and the source gas is decomposed by the plasma 11 and deposited on the translucent insulating substrate 2 and the cathode electrode 40 to form i-type amorphous. A silicon film is formed. The conditions for forming the i-type amorphous silicon film are the same as those in step S10 of the first embodiment. The RF power to the cathode electrodes 401 to 408 is set to 10W.

  After the i-type amorphous silicon film is formed, when the dummy substrate is carried out of the film forming chamber 18, the i-type amorphous silicon film remains on the cathode electrodes 401 to 408 in the film forming chamber 18.

  Next, the desorption hydrogen atom amount profile of the i-type amorphous silicon film deposited on each cathode electrode 401 to 408 is measured for each cathode electrode 401 to 408 region. The amorphous silicon film formed on the cathode electrodes 401 to 408 is heated for each cathode electrode 401 to 408 region. Heating is performed by heating any region of the cathode electrodes 401 to 408. The exhaust device 17 evacuates the film forming chamber 18 through the gas discharge pipe 9, introduces argon (Ar) gas into the film forming chamber 18 from the gas supply source 3 b through the gas supply pipe 3, A high frequency power is applied to each of the cathode electrodes 401 to 408 to generate plasma between the anode electrode 1 and the cathode electrode 40. The plasma generation conditions here are the same as in step S20 of the first embodiment. The RF power to the cathode electrodes 401 to 408 is set to 250W.

  The temperature of each cathode electrode 401 to 408 is controlled by the heat input from the plasma to each cathode electrode 401 to 408 and the control of the amount of cooling water supplied to the cooling water pipe corresponding to each cathode electrode 401 to 408 individually. Then, the i-type amorphous silicon film deposited on each of the cathode electrodes 401 to 408 is heated. Control of the amount of cooling water supplied to the cooling water piping is performed by an individual cooling water control device corresponding to each. Here, the method of controlling the temperature of each cathode electrode 401-408 by heating the area | region of each cathode electrode 401-408 independently with a lamp | ramp from the back side of each cathode electrode 401-408, or each cathode electrode 401-408 A method of heating a region of each cathode electrode 401 to 408 independently by disposing a resistance wire heater can be used.

  By such control, for example, the temperature of each cathode electrode 401 to 408 rises to 450 ° C. after 500 seconds at a constant temperature increase speed. Due to this temperature rise, hydrogen atoms are desorbed from the i-type amorphous silicon film formed on each of the cathode electrodes 401 to 408 and are discharged from the film forming chamber 18 through the gas discharge pipe 9 together with Ar gas or the like. . Then, by measuring the amount of desorbed hydrogen atoms in the discharged gas with the mass analyzer 10, the amount of desorbed hydrogen atoms desorbed from the heated i-type amorphous silicon film is measured.

  Next, the desorption hydrogen atomic weight profile of the i-type amorphous silicon film deposited on each of the cathode electrodes 401 to 408 is examined, and the i-type amorphous silicon is set so that the half width (° C.) becomes 20 ° C. ± 10 ° C. The RF power under the film forming conditions is reset independently for each of the cathode electrodes 401 to 408, and the reset RF power conditions are used from the next film forming.

  After the 100th, 200th, 300th, 400th, and 500th i-type amorphous silicon films are formed in this way, RF power is supplied to each of the eight cathode electrodes 401 to 408 independently. The half-value width (° C.) in the desorbed hydrogen atomic weight profile is measured in each zone of the eight cathode electrodes 401 to 408, and compared with the latest preset value set in advance, the RF power of each cathode electrode 401 to 408 is After resetting, an i-type amorphous silicon film is formed.

  According to the above procedure, i-type amorphous silicon film was formed 600 times. As a result, the half-value width (° C.) in the desorption hydrogen amount profile of the i-type amorphous silicon film deposited in the regions of the cathode electrodes 401 to 408 during the first to 600th deposition of the i-type amorphous silicon film. ) Could be controlled to 20 ° C. ± 10 C as shown in FIG. FIG. 12 is a characteristic diagram showing the relationship between the number of depositions of the i-type amorphous silicon film deposited by the deposition method according to the second embodiment and the half-value width (° C.) in the desorbed hydrogen atomic weight profile.

  If the i-type amorphous silicon film deposited on each of the cathode electrodes 401 to 408 is heated by the above method and the power applied to each of the cathode electrodes 401 to 408 is reset, the in-plane of the heated cathode electrode 40 Since the region and the region of the cathode electrode 40 where the RF power is reset coincide with each other, there is an advantage that the film quality of each region can be easily optimized. As a result, the film quality in the substrate surface can be made relatively easy. From the results shown in FIG. 12, it can be seen that the film quality of the i-type amorphous silicon film can be optimized and the uniformity of the film quality in each region within the substrate surface can be improved.

  In this way, the i-type amorphous silicon film formed for the 600th time after preventing the deterioration of the film quality and improving the uniformity of the film quality in the surface is applied to the power generation layer of the photoelectric conversion layer. Thin-film solar cells were prepared and evaluated in the same manner as in Embodiment 1. 81 amorphous silicon solar cells of 50 mm square size were equally arranged at 50 mm intervals on a 950 mm square alkali-free glass substrate, and the photoelectric conversion efficiency of all the cells was evaluated.

  As a result, the uniformity in the surface of the photoelectric conversion efficiency of the amorphous silicon solar cell is ± 5.6% (photoelectric conversion efficiency: 9.5%) when the film forming conditions are not corrected. Variation of the photoelectric conversion efficiency when the regions of the cathode electrodes 401 to 408 are independently corrected with the RF power is ± 2% (photoelectric conversion efficiency: 10.3%). 9.9%), which was a significant improvement. This is considered to be due to the improved in-plane distribution of the quality of the i-type amorphous silicon film in the substrate plane.

  Therefore, according to the second embodiment, similarly to the first embodiment, a high-quality i-type amorphous silicon film having a large area and excellent in film quality can be stably produced with high yield without lowering the productivity as compared with the conventional method. It is possible to make it. Then, by using this i-type amorphous silicon film for the power generation layer of the photoelectric conversion layer, a thin film solar cell excellent in photoelectric conversion efficiency can be obtained.

  In addition, according to the second embodiment, the RF power applied to each cathode electrode 401 to 408 can be corrected independently, so that a high-quality i with a large area excellent in the in-plane distribution of film quality in the substrate plane. A type of amorphous silicon film can be stably manufactured with a high yield. Then, by using this i-type amorphous silicon film for the power generation layer of the photoelectric conversion layer, a thin film solar cell excellent in photoelectric conversion efficiency can be obtained.

  As described above, the method for manufacturing a semiconductor film according to the present invention is useful when a large-area high-quality semiconductor film is stably and easily manufactured.

DESCRIPTION OF SYMBOLS 1 Anode electrode 2 Translucent insulated substrate 3 Gas supply piping 3a Gas supply port 3b Gas supply source 4 Cathode electrode 5 Power supply 6 Distributor 9 Gas exhaust piping 10 Mass spectrometer 11 Plasma 16 Amorphous silicon film 17 Exhaust device 18 Made Membrane chamber 40 Cathode electrode 41-44 Cathode electrode 71-74 Power monitor 81-84 Matching device 101 Lamp 102 Resistance wire heater 121-124 Temperature control device 131-134 Cooling water control device 141-144 Cooling water piping 401-408 Cathode electrode

Claims (15)

Power is supplied to the cathode electrode in a state where the raw material gas is supplied into the film forming chamber in which the substrate to be processed is held on the anode electrode to generate plasma between the cathode electrode and the anode electrode, A method of manufacturing a semiconductor film, in which a semiconductor film is formed by decomposing a source gas and depositing it on a film forming surface of the substrate to be processed,
Electric power is supplied to the cathode electrode while supplying the source gas into the film forming chamber under a first film forming condition to generate plasma between the cathode electrode and the anode electrode, so that the semiconductor film becomes the cathode. A first step of forming a film on the electrode;
A second step of heating the semiconductor film deposited on the cathode electrode by heating the cathode electrode;
A third step of measuring the number of desorbed hydrogen atoms separated from the heated semiconductor film a plurality of times according to the temperature of the cathode electrode;
A fourth step of analyzing the measurement result of the amount of desorbed hydrogen atoms and acquiring film quality information serving as an index for adjusting the film forming conditions to reflect the film quality of the semiconductor film;
A fifth step of resetting the film forming condition of the semiconductor film to the second film forming condition based on the film quality information;
A sixth step of holding the substrate to be processed on the anode electrode;
Electric power is supplied to the cathode electrode while supplying a source gas into the film forming chamber under the second film forming condition, and plasma is generated between the cathode electrode and the anode electrode to cover the semiconductor film with the film. A seventh step of forming a film on the surface of the substrate to be processed;
A method for producing a semiconductor film, comprising: In the second step, the temperature of the cathode electrode is independently controlled for each of a plurality of regions in the plane of the cathode electrode, and the cathode electrode is heated to thereby form a semiconductor film deposited on the cathode electrode. Heating independently for each of a plurality of regions in the plane,
The method of manufacturing a semiconductor film according to claim 1. While controlling the temperature of the cathode electrode by generating a plasma between the cathode electrode and the anode electrode and heating the cathode electrode by heat input to the cathode electrode by the plasma and cooling the cathode electrode Heating the semiconductor film;
The method for producing a semiconductor film according to claim 2. Heating the semiconductor film while controlling the temperature of the cathode electrode by heating the cathode electrode with lamp light;
The method for producing a semiconductor film according to claim 2. Heating the semiconductor film while controlling the temperature of the cathode electrode by heating the cathode electrode with a resistance wire heater;
The method for producing a semiconductor film according to claim 2. In the third step, measuring the amount of hydrogen atoms by measuring the amount of hydrogen atoms in the gas discharged from the film forming chamber using a mass analyzer,
The method of manufacturing a semiconductor film according to claim 1. In the fifth step, resetting the high frequency power supplied to the cathode electrode among the first film forming conditions,
The method of manufacturing a semiconductor film according to claim 1. The semiconductor film is an amorphous silicon film, an amorphous silicon carbide film, an amorphous silicon oxide film, an amorphous silicon germanium film, a microcrystalline silicon film, a microcrystalline silicon carbide film, a microcrystalline silicon oxide film, or a microcrystalline silicon germanium. Being a membrane,
The method of manufacturing a semiconductor film according to claim 1. A film forming chamber;
Source gas introduction means for introducing source gas into the film forming chamber;
Discharging means for discharging the gas in the film forming chamber;
An anode electrode disposed in the film forming chamber and holding a substrate to be processed;
A cathode electrode disposed opposite to the anode electrode, to which electric power is supplied to generate plasma of the source gas between the anode electrode;
Temperature control means for heating the cathode electrode while controlling the temperature of the cathode electrode;
Measuring means for measuring the amount of hydrogen atoms in the gas discharged from the film forming chamber by the discharging means;
An apparatus for manufacturing a semiconductor film, comprising: The temperature control means for heating the cathode electrode while controlling the temperature independently for each of a plurality of regions in the surface of the cathode electrode;
The semiconductor film manufacturing apparatus according to claim 9. Power is applied independently for each of a plurality of regions in the surface of the cathode electrode;
The apparatus for manufacturing a semiconductor film according to claim 10. The temperature control means comprises heating means for heating the cathode electrode and cooling means for cooling the cathode electrode;
The semiconductor film manufacturing apparatus according to claim 9. Providing the lamp in the film forming chamber as the heating means;
The apparatus for manufacturing a semiconductor film according to claim 12. Providing the resistance wire heater in the film forming chamber as the heating means;
The apparatus for manufacturing a semiconductor film according to claim 12. As the cooling means, water cooling piping is provided in the film forming chamber,
The apparatus for manufacturing a semiconductor film according to claim 12.

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