TWI494466B - Plasma film forming apparatus, crystal solar cell and semiconductor element - Google Patents

Description

Plasma film forming device, crystalline solar cell and semiconductor component

The present invention relates to a plasma film forming apparatus which forms a plasma to form a film.

In the manufacturing step of a semiconductor device, a plasma film forming apparatus is used in the film forming step because of the advantage of easily controlling the process with high precision. For example, as a plasma film forming apparatus, a plasma Vapor Deposition (CVD) apparatus is known.

In the plasma CVD apparatus, the material gas is plasma-formed by high-frequency power or the like, and then a thin film is formed on the substrate by a chemical reaction. A plasma CVD apparatus has been proposed which has a plurality of electrode plates prepared and arranges the substrates on the respective electrode plates, thereby improving the processing capability (see, for example, Patent Document 1).

Prior technical literature

Patent literature

Patent Document 1: International Patent Publication No. 02/20871

In order to form a film on all the substrates in a chamber uniformly and with high film forming efficiency, a method is employed in which a shower electrode for supplying a process gas from inside the electrode is used. However, in order to uniformly eject the process gas from the shower electrode, it is necessary to uniformly disperse the process gas inside the electrode. In particular, the substrate is mounted on a plurality of substrates In the case of an electrode, in order to uniformly disperse the above process gas, it is necessary to use a shower electrode as a large-sized shower electrode. As a result, there is a problem that the plasma film forming apparatus is increased in size.

In view of the above problems, an object of the present invention is to provide a plasma film forming apparatus capable of efficiently forming a uniform film on a substrate and suppressing an increase in size.

According to an aspect of the present invention, there is provided a plasma film forming apparatus including: a chamber into which a substrate holder is carried, a substrate holder having a mounting surface, a mounting surface on which the substrate is mounted, and a cathode electrode; Arranged so as to face the mounting surface, the mounting surface is arranged to extend in the vertical direction in the chamber; the gas supply device introduces the process gas between the substrate holder and the cathode electrode in the chamber; and an AC power source. The alternating current power is supplied between the substrate holder and the cathode electrode, and the process gas is brought into a plasma state between the substrate holder and the cathode electrode, and a film containing a raw material contained in the process gas as a main component is formed on the substrate.

According to an aspect of the present invention, there is provided a plasma film forming apparatus which forms a film on a substrate, and includes: a chamber accommodating the substrate; a substrate carrier plate disposed in the chamber and mounted thereon a substrate; a high-frequency electrode disposed in the chamber and facing the substrate on the substrate carrier; and a gas supply mechanism for using a pretreatment gas containing hydrogen or a reaction gas of a material gas including a thin film formed on the substrate a supply to the chamber; and an alternating current source for supplying alternating current power to the substrate carrier and the high frequency electrode At the different stages of the film forming step, respectively, the plasma is contained on the upper surface of the substrate: either a plasma containing a pretreatment gas or a plasma containing a material gas.

According to the present invention, it is possible to provide a plasma film forming apparatus capable of efficiently forming a uniform film on a substrate and suppressing an increase in size.

(First embodiment)

Next, an embodiment of the present invention will be described with reference to the drawings. In the description of the following drawings, the same or similar symbols are attached to the same or similar parts. However, it should be noted that the schema is a graphical representation. In the following embodiments, the apparatus or method for embodying the technical idea of the present invention is exemplified, and the structure, arrangement, and the like of the components of the embodiment of the present invention are not specified as follows. Construction, configuration, etc. The embodiments of the present invention can be variously modified within the scope of the patent application.

As shown in Fig. 1, a plasma film forming apparatus 10 according to an embodiment of the present invention includes a chamber 20 into which a substrate holder 11 having a mounting surface 110 and a mounting surface 110 mounted thereon a substrate 1; a cathode electrode 12 disposed in the chamber 20; a gas supply device 13 for introducing the process gas 100 into the substrate holder 11 and the cathode electrode 12 in the chamber 20; and an AC power source 14 for alternating current power The process gas 100 is supplied between the substrate holder 11 and the cathode electrode 12 to bring the process gas 100 into a plasma state between the substrate holder 11 and the cathode electrode 12. Cathode electrode 12 The mounting surface 110 is disposed to face the mounting surface 110 so as to extend in the vertical direction in the chamber 20 . According to the plasma film forming apparatus 10, a film containing a raw material contained in the process gas 100 as a main component is formed on the substrate 1.

In the plasma film forming apparatus 10, the substrate holder 11 is used as an anode electrode. In the example shown in FIG. 1, the substrate holder 11 is grounded.

The substrate holder 11 can have, for example, a configuration in which a cross section perpendicular to the mounting surface 110 has a comb shape. That is, the substrate holder 11 shown in FIG. 2 can be employed, and the substrate holder 11 includes a plurality of substrate mounting plates 111 that define the mounting surface 110 as a main surface and are spaced apart from each other and arranged in parallel; The fixing plate 112 fixes the bottom of each of the substrate mounting plates 111. In FIG. 2, an example in which the substrate mounting plate 111 is five blocks is shown, but the number of the substrate mounting plates 111 is not limited to five.

At this time, as shown in FIG. 1 , the plurality of substrate mounting plates 111 are arranged so as to alternate with the plurality of cathode electrodes 12 and to have the outermost side of the substrate mounting plate 111 . The mounting surface 110 is defined as a surface of the substrate mounting plate 111 facing the cathode electrode 12, respectively.

In the plasma film forming apparatus 10, the substrate holder 11 in a state in which the substrate 1 is mounted is carried into the chamber 20. Then, the process gas 100 including the material gas for film formation is introduced into the chamber 20 from the gas supply device 13.

After the process gas 100 is introduced, the pressure in the chamber 20 is adjusted by the exhaust device 15. Process gas 100 within chamber 20 After the pressure is adjusted to a predetermined gas pressure, predetermined AC power is supplied to the cathode electrode 12 and the substrate holder 11 by the AC power source 14. Thereby, the process gas 100 in the chamber 20 is plasmad. The substrate 1 is exposed to the formed plasma, whereby a desired film containing a raw material contained in the material gas as a main component is formed on the exposed surface of the substrate 1. Furthermore, the temperature of the substrate 1 in the film formation process can also be set by the substrate heater which has been omitted. By setting the temperature of the substrate 1 in the film formation process to a predetermined temperature, the film formation speed can be increased or the quality of the film can be improved.

In the plasma film forming apparatus 10, a desired film can be formed by appropriately selecting a material gas. For example, a germanium semiconductor film, a tantalum nitride film, a hafnium oxide film, a hafnium oxynitride film, a carbon thin film, or the like can be formed on the substrate 1. Specifically, a tantalum nitride (SiN) film is formed on the substrate 1 by using a mixed gas of ammonia (NH ₃ ) gas and decane (SiH ₄ ) gas. Alternatively, a cerium oxide (SiOx) film is formed on the substrate 1 by using a mixed gas of decane (SiH ₄ ) gas and nitrous oxide (N ₂ O) gas.

For example, as shown in FIG. 3, a through hole 120 is formed in the cathode electrode 12, and the through hole 120 penetrates the cathode electrode 12 in the thickness direction. The opening of the through hole 120 is formed on the surface of the cathode electrode 12 so as to face the mounting surface 110 of the substrate mounting plate 111. FIG. 3 exemplifies a case where the substrate mounting plate 111 of the substrate holder 11 is three pieces and the cathode electrode 12 is two pieces.

The cathode electrode 12 provided with an opening on the surface functions as a hollow cathode electrode which is a hollow cathode electrode The electrode produces a hollow cathode discharge. During the hollow cathode discharge process, electrons are enclosed inside the cathode electrode 12 having no electric field, thereby forming a space of high-density electrons which are incident on the surface of the cathode electrode 12 due to ions (ion) from the cathode electrode. 12 emitted electrons. Gas molecules that invade into the high electron density region repeatedly recombine and recombine, and when recombined, are observed to emit high-intensity light. The precursor generated in the high-density plasma is a radical species, and the precursor diffuses toward the outside of the through hole 120 regardless of the electrode potential, and is disposed on the mounting surface 110 of the substrate mounting plate 111. A film is formed on the surface of the substrate 1.

On the other hand, in the cathode electrode 12A shown in FIG. 4, the process gas 100 is uniformly discharged from the concave portion 401, which generates a high-density plasma by hollow cathode discharge, and the cathode electrode 12A shown in FIG. The shower electrode structure of the process gas 100 is internally supplied, and a concave portion 401 is formed on the surface. Thereby, the uniformity of the plasma can be obtained on the entire surface of the cathode electrode 12A.

However, with the cathode electrode 12A shown in FIG. 4, it is difficult to uniformly supply the process gas 100 to the plurality of concave portions 401, and the opening diameter or length of the gas ejection port 402, the flow rate or pressure of the process gas 100, and the like have various limitations. . Further, since the diameter of the gas discharge port 402 is an extremely small diameter of about 0.3 mm to 0.4 mm, clogging is likely to occur. When the process gas 100 cannot be introduced due to clogging, the hollow cathode discharge does not occur in the clogging recess 401. Therefore, the uniformity of discharge on the entire surface of the cathode electrode 12A cannot be maintained.

On the other hand, the cathode electrode 12 shown in FIG. 3 does not pass through. The process gas 100 is introduced into the cathode electrode 12. The diameter of the through hole 120 is sufficiently larger than the diameter of the hole required for the shower electrode, and therefore, there is no need to worry about clogging, and maintenance is also easy. The diameter of the through hole 120 is about 3.8 mm to 8.0 mm, for example, 5 mm.

Further, the plasma excited on both surfaces of the cathode electrode 12 shown in FIG. 3 is connected by the through holes 120. Therefore, the difference in the density of the plasma concentrations on both faces of the cathode electrode 12 is naturally corrected, and a plasma space having a uniform density can be produced on both faces of the cathode electrode 12.

As described above, a multi-hollow cathode structure in which a plurality of through holes 120 are formed in the cathode electrode 12 is employed, whereby a uniform multi-hollow discharge can be obtained on both faces of the cathode electrode 12. . The "multiple hollow discharge" means a discharge generated on the surface of the cathode electrode 12 after the hollow cathodes respectively generated in the respective through holes 120 are combined. Thereby, a uniform high-density plasma can be realized on the surface of the cathode electrode 12. As a result, the material gas is efficiently decomposed, and a thin film is formed on the substrate 1 at a high speed, a large area, and uniformly.

The through hole 120 is preferably densely disposed on the surface of the cathode electrode 12. The through holes 120 are disposed at the highest possible density, whereby a uniform high electron density electric field can be easily formed on both faces of the cathode electrode 12. FIG. 5 shows an example of the surface of the cathode electrode 12 in which the opening of the through hole 120 is formed.

Further, it is preferable that the inner surface of the through hole 120 of the cathode electrode 12 is made of a material having a good secondary electron emissivity and subjected to surface treatment. For example, a carbon material that is inexpensive, easy to process, and easy to perform maintenance such as cleaning is suitable for As the material of the cathode electrode 12. For example, the cathode electrode 12 of the carbon material can be cleaned by hydrofluoric acid treatment. Moreover, by using a carbon material, deformation does not occur due to the high temperature in the plasma processing step. Alternatively, an aluminum alloy or the like which easily forms a metal oxide film is also a material suitable for a hollow cathode electrode. Further, carbon containing carbon fibers, a stainless steel alloy, copper, a copper alloy, glass, ceramics, or the like can be used for the cathode electrode 12. Alternatively, the above materials may be coated by alumite treatment, plating, and thermal spraying.

For the substrate holder 11 used as the anode electrode, a carbon material can also be suitably used. Further, carbon, carbon-containing carbon, stainless steel alloy, copper, copper alloy, glass, ceramics, or the like can be used for the substrate holder 11. Alternatively, the above materials may be applied by alumite treatment, plating, and melt blowing.

Preferably, in the chamber 20, the process gas 100 is introduced from the lower side toward the upper side and introduced between the substrate holder 11 and the cathode electrode 12. By introducing the process gas 100 from below, the plasma gas molecules and radical particles having a small specific gravity flow upward as they are, and naturally flow upward on the surface of the cathode electrode 12. Therefore, even if a complicated structure such as a shower electrode is not used, the process gas is uniformly supplied to the surface of the cathode electrode 12.

Further, the surface of the cathode electrode 12 is preferably flat to the extent indicated by a finish mark "▽▽▽" to allow the process gas 100 to smoothly flow. That is, it is preferable that the maximum height Ry is less than 6.3 S, the ten-point average roughness Rz is less than 6.3 Z, and the arithmetic mean roughness Ra is less than 1.6 a. The surface roughness of the cathode electrode 12 is reduced, whereby the formation can be improved The growth rate of the film of the substrate 1.

Similarly, the surface of the substrate holder 11 is also preferably flat to the extent indicated by the processing symbol "▽▽". That is, it is preferable that the maximum height Ry is less than 25 S, the ten-point average roughness Rz is less than 25 Z, and the arithmetic mean roughness Ra is less than 6.3 a.

In order to introduce the process gas 100 upward from the bottom, as shown in FIG. 6, a gas supply nozzle (notch) 130 is disposed directly below the cathode electrode 12 along the bottom surface of the cathode electrode 12, and the gas supply nozzle 130 supplies gas. The process gas 100 of the apparatus 13 is ejected. The process gas 100 is ejected from the gas supply nozzle 130 toward the bottom of the cathode electrode 12, whereby the process gas 100 can be supplied to the both surfaces of the cathode electrode 12 substantially uniformly.

At this time, when the substrate holder 11 is in the shape including the fixing plate 112 as shown in FIG. 2, as shown in FIG. 6, the gas introduction hole 113 is located between the substrate mounting plates 111 and is formed on the fixing plate 112, the gas. The introduction hole 113 penetrates the fixing plate 112 in the vertical direction. The process gas 100 is introduced between the substrate mounting plate 111 and the cathode electrode 12 from below the chamber 20 via the gas introduction hole 113. Further, as shown in FIG. 6, when the substrate holder 11 is supported by the support table 30 in the chamber 20, the introduction hole 31 is formed at a position of the support table 30 corresponding to the gas introduction hole 113. The introduction hole 31 penetrates the support base 30 in the vertical direction.

When a plurality of gas supply nozzles 130 are present, as shown in FIG. 7, the gas supply nozzles 130 are arranged along the bottom surface of the cathode electrode 12. As shown in FIG. 8 in which the substrate mounting plate 111 is shown through the cathode electrode 12, the mounting surface 110 is defined as the substrate mounting plate 111 facing the cathode electrode 12, respectively. Face. Thereby, the substrate 1 and the cathode electrode 12 are arranged to face each other.

An example of the shape of the discharge port of the gas supply nozzle 130 is shown in Figs. 9(a) to 9(c). Fig. 9 (a) is an example in which a groove is formed at the tip end of the cylindrical gas supply nozzle 130 along the diameter, and the discharge port is disposed at the center portion of the groove. (b) of FIG. 9 is an example in which a concave portion is provided at the tip end of the cylindrical gas supply nozzle 130, and the discharge port is disposed at a central portion of the bottom surface of the concave portion. (c) of FIG. 9 is an example in which the discharge port is disposed at a central portion of the front end of the cylindrical gas supply nozzle 130.

When the process gas 100 is a gas obtained by mixing a plurality of gases, the process gas 100 obtained by mixing all of the gases may be supplied from the gas supply nozzle 130, and the nozzles 130 may be supplied from different gases for each gas. The gas is supplied separately.

An example of the configuration of the exhaust device 15 is shown in Fig. 10 . The exhaust device 15 shown in Fig. 10 is disposed at an upper portion of the chamber 20 which has been omitted. The exhaust device 15 includes a first exhaust gas adjustment plate 151 disposed above the substrate holder 11 and the cathode electrode 12, and a frame-shaped second exhaust gas adjustment plate 152 positioned outside the first exhaust gas adjustment plate 151. It is arranged in the way below the edge. As shown in FIG. 10, the process gas 100 that has flowed into the upper side of the substrate holder 11 and the cathode electrode 12 is adjusted from the first exhaust gas by the gap between the first exhaust gas adjustment plate 151 and the second exhaust gas adjustment plate 152. The outer edge portion of the plate 151 is discharged to the outside of the chamber 20. The exhaust device 15 controls the amount of the exhaust gas by controlling the size of the gap between the first exhaust gas adjustment plate 151 and the second exhaust gas adjustment plate 152.

Another configuration example of the exhaust device 15 is shown in Fig. 11 . The exhaust device 15 shown in FIG. 11 includes a plurality of exhaust holes 150 that are disposed at an upper portion of the chamber 20 that has been omitted, and that penetrate in the vertical direction. The process gas 100 is exhausted toward the outside of the chamber 20 via the exhaust hole 150. The exhaust device 15 adjusts the amount of exhaust gas by controlling the opening degree of the exhaust hole 150.

According to the plasma film forming apparatus 10 of the embodiment of the present invention, the substrate holder 11 is used as an anode electrode, whereby the substrate 1 can be placed in the chamber 20 while the film formation surface of the substrate 1 is perpendicular. Therefore, the plurality of cathode electrodes 12 are disposed in the chamber 20. Therefore, the plasma film forming apparatus 10 shown in FIG. 1 can store a large number of substrates 1 in the chamber 20 at the same time as compared with the plasma film forming apparatus described below, and the processing ability can be remarkably improved. In the membrane device, the substrate 1 having the film formation surface facing the vertical direction is mounted on a substrate carrier or the like of the flat plate, and a film formation process is performed.

Further, by using the cathode electrode 12 in which the through hole 120 is formed, uniform and high-density plasma can be stably generated on both surfaces of the cathode electrode 12. At this time, regardless of the frequency of the AC power supplied from the AC power source 14, uniform high-density plasma can be generated over a large area. Even if the frequency of the AC power supplied from the AC power source 14 is set to, for example, about 60 Hz to 27 MHz, a uniform and high-density plasma can be generated. That is, it is not necessary to use an expensive AC power source that supplies AC power in a Very High Frequency (VHF) band. For the plasma film forming apparatus 10, for example, even in a low frequency radio frequency (RF) band such as 250 kHz, a plasma forming apparatus can be obtained from the prior art. For the high-density plasma of the same or higher, the above-mentioned plasma plasma film forming apparatus uses an AC power source of a VHF band.

As a result, a large-area film can be formed on the substrate 1 at a high speed and uniformly. That is, according to the plasma film forming apparatus 10, the film thickness of the formed film and the uniformity of the film quality are improved, and the film forming speed is increased.

Further, the plasma film forming apparatus 10 does not need to use a shower electrode having a complicated structure and having to form fine pores. Therefore, frequent maintenance like a shower electrode is not required. Further, the shower electrode must be enlarged to uniformly disperse the process gas 100, whereas the plasma film forming apparatus 10 does not need to be enlarged. Therefore, according to the plasma film forming apparatus 10, it is possible to provide a plasma film forming apparatus capable of efficiently forming a uniform film on all the substrates in the chamber 20 and suppressing an increase in size.

Further, compared with the plasma film forming apparatus using the shower electrode as follows, the manufacturing period of the plasma film forming apparatus 10 is short, and the manufacturing yield is improved, and the shower electrode must process thousands or more of fine pores. Therefore, the manufacturing cost of the plasma film forming apparatus 10 is suppressed.

FIG. 12 shows an example in which the AC power output from the AC power source 14 is supplied between the substrate holder 11 and the cathode electrode 12 via a pulse generator 16. In the example shown in Fig. 12, the output of the pulse generator 16 is supplied to the cathode electrode 12, and the substrate holder 11 is grounded. The supply of the alternating current power is stopped at a fixed cycle, whereby the plasma is stably formed in the chamber 20. The reason is that the stop period is set during the supply of the alternating current power, whereby the temperature of the electrons is lowered and the stability of the discharge is improved. However, if the off time is set too long, then Power efficiency will drop, so you need to be careful.

For example, the ON time for supplying AC power is 600 microseconds, and the off time for stopping the supply of AC power is 50 microseconds, so that the on time and the off time alternately appear alternately, and the communication is performed. Power is supplied between the substrate holder 11 and the cathode electrode 12. Further, it is preferable to set the on-time to a range of about 100 microseconds to 1000 microseconds, and to set the off-time to a range of about 10 microseconds to 100 microseconds.

In the above-described manner, the supply of the alternating current power between the substrate holder 11 and the cathode electrode 12 is pulse-controlled, and the supply of the alternating current power is periodically turned on and off, whereby the occurrence of abnormal discharge can be suppressed.

FIG. 13 shows an example in which an AC power source 17 is attached to the substrate holder 11 as an anode electrode in addition to the AC power source 14 mounted on the cathode electrode 12. By supplying AC power to the anode electrode, the film quality of the thin film formed on the substrate 1 can be improved. The frequency of the AC power supplied from the AC power source 17 may be equal to or lower than the frequency of the AC power supplied from the AC power source 14 or lower than the AC power supplied from the AC power source 14. For example, the frequency of the AC power supplied from the AC power source 17 is set to about 60 Hz to 27 MHz.

Further, the AC power is not supplied from the AC power source 14, but the AC power is supplied from the AC power source 17, whereby the substrate 1 can be subjected to plasma cleaning. For example, the sputtering gas is introduced into the chamber 20, and the substrate 1 is cleaned by sputtering etching while supplying AC power from the AC power source 17.

Furthermore, as shown in FIG. 14, the power splitter can be used. The output of the AC power source 14 is divided by 18, and the divided AC power is supplied to the cathode electrode 12 and the substrate holder 11, respectively. Thereby, the number of AC power sources can be reduced as compared with FIG. The power supplied to the substrate holder 11 may be smaller than the power supplied to the cathode electrode 12. For example, 90% to 100% of AC power is supplied to the cathode electrode 12, and 10% to 0% of AC power is supplied to the substrate holder 11.

The plasma film forming apparatus 10 shown in Fig. 1 can be used, for example, as a film forming chamber of an in-line film forming apparatus. FIG. 15 shows an example of the in-line film forming apparatus 200 including the three chambers of the charging/heating chamber 210, the film forming chamber 220, and the take-out chamber 230.

In the in-line film forming apparatus 200, the substrate holder 11 on which the substrate 1 is mounted is placed in the insertion/heating chamber 210. After the substrate 1 is preheated to a predetermined temperature in the charging/heating chamber 210, the substrate holder 11 is transferred from the loading/heating chamber 210 to the film forming chamber 220 via the opening and closing type gate 240A. In the film forming chamber 220, after the substrate 1 is formed into a thin film, the substrate holder 11 is transferred from the film forming chamber 220 to the take-out chamber 230 via the opening and closing type shutter 240B. Then, the substrate holder 11 is taken out from the take-out chamber 230. The substrate holder 11 is transported between the respective chambers of the in-line film forming apparatus 200 by a transport device that has been omitted.

Further, as shown in Fig. 16, the chamber 20 is preferably cylindrical. By setting it to a cylindrical shape, the chamber 20 can have sufficient strength as a vacuum container. Therefore, even if the thickness of the chamber 20 is made thin, including the heating, sufficient strength can be achieved with an inexpensive and simple structure.

An example of the configuration of the insertion/heating chamber 210 is shown in FIG. Put in/heat The chamber 210 includes a heater 211A disposed above and below the substrate holder 11 and a slot heater 211B disposed between the substrate mounting plates 111 in parallel with the substrate mounting plate 111. The substrate holder 11 is supported in the insertion/heating chamber 210 by the support table 212. Further, a heat insulating plate 213 is disposed between the support table 212 and the tank heater 211B.

The tank heater 211B heats the substrate 1 mounted on the substrate holder 11 and the mounting surface 110, thereby preventing a temperature difference between the substrate 1 and the substrate holder 11. For example, when pre-heating is performed while monitoring the temperature of the substrate holder 11, the temperature of the substrate 1 can be accurately adjusted.

The heater 211A and the tank heater 211B can be a lamp heater, a ceramics heater, a sheath heater, an induction heater or the like.

In the above description, an example of the in-line film forming apparatus 200 including three chambers is shown. However, the plasma film forming apparatus 10 shown in FIG. 1 may be applied to an in-line type including two chambers as shown in FIG. Film forming apparatus 200. In the in-line film forming apparatus 200 including the two chambers of the heating chamber 211 and the film forming chamber 220, the substrate holder 11 is placed and taken out in the heating chamber 211. After the substrate 1 placed in the heating chamber 211 is preheated to a predetermined temperature in the heating chamber 211, the substrate holder 11 is transferred to the film forming chamber 220 via the opening and closing shutter 241. In the film forming chamber 220, after the substrate 1 is formed into a thin film, the substrate holder 11 is transferred to the heating chamber 211 via the shutter 241. Then, the substrate holder 11 is taken out from the heating chamber 211. Further, similarly to the charging/heating chamber 210 shown in FIG. 17, it is preferable that the heating chamber 211 shown in FIG. 18 has the groove heater 211B disposed between the substrate mounting plates 111.

As described above, the present invention is described by the embodiments, but it should be understood that the invention is not limited by the description and the drawings. In view of the above disclosure, various alternative embodiments, examples, and operational techniques are apparent to those of ordinary skill in the art.

For example, an example has been shown in which the substrate holder 11 includes a plurality of substrate mounting plates 111 and fixing plates 112, but the shape of the substrate holder 11 is not limited thereto. For example, the substrate holder 11 can also be a single plate.

(Second embodiment)

FIG. 19 is a schematic view showing a configuration of a plasma film forming apparatus according to a second embodiment of the present invention. FIG. 20 is a flowchart for explaining a method of forming a thin film using the thin film forming apparatus of the second embodiment of the present invention. Hereinafter, an example of a method of forming a film will be described with reference to FIGS. 19 and 20.

In step S11, the semiconductor substrate for film formation processing, that is, the substrate 500, is housed in the chamber 511.

In step S12, a pretreatment gas 121 is introduced into the chamber 511 by the gas supply mechanism 515. The pretreatment gas 121 is preferably a mixed gas of ammonia (NH ₃ ) gas, ammonia gas and nitrogen gas (N ₂ ).

In step S13, the chamber 511 is accessed by the gas discharge mechanism 516. The pressure is reduced internally, and the pressure of the pretreatment gas 121 in the chamber 511 is set to a predetermined value.

In step S14, the AC power supply 514 is turned on, and predetermined AC power is supplied between the substrate carrier 512 and the high-frequency electrode 513 via a matching box 541. Here, the groove 532 is not provided in the high-frequency electrode 513, and the high-frequency electrode 513 is a simple plate electrode. A parallel plate-type electrode is formed by the substrate carrier 512 and the high-frequency electrode 513. Thereby, the pretreatment gas 121 in the chamber 511 is plasma-formed, and film formation pretreatment is started. That is, the surface of the substrate 500 before film formation is exposed to a high-frequency plasma of ammonia (hereinafter referred to as "ammonia plasma"), and hydrogen radicals in the ammonia plasma are combined with a dangling bond of the substrate 500. .

After the film formation pretreatment is performed for a predetermined period of time, in step S15, the AC power supply 514 is turned off, and the film formation pretreatment is completed. Then, in step S16, the pretreatment gas 121 is discharged by the gas discharge mechanism 516 to bring a high vacuum into the chamber 511.

Next, in step S17, the reaction gas 122 is introduced into the chamber 511 by the gas supply mechanism 515. Next, in step S18, the inside of the chamber 511 is depressurized by the gas discharge mechanism 516, and the reaction gas 122 in the chamber 511 is adjusted to a predetermined gas pressure.

Then, in step S19, the AC power supply 514 is turned on, and the predetermined AC power is supplied to the substrate carrier 512 and the high-frequency electrode 513 via the AC power supply 514 via the matching unit 541. Thereby, the reaction gas 122 containing the material gas in the chamber 511 is plasma-formed. Exposing the substrate 500 to the formed plasma to cause the excited species in the plasma to be on the surface of the substrate 500 A reaction occurs to form a film on the surface of the substrate 500.

After the film has grown to a predetermined film thickness, the AC power supply 514 is turned off in step S20, and the film formation process is completed. Then, in step S21, the reaction gas 122 is discharged by the gas discharge mechanism 516 to bring a high vacuum into the chamber 511. A film is formed on the substrate 500 by the above steps.

In the above description, the following example has been described. This example means that the pretreatment gas 121 is discharged from the chamber 511 in step S16. However, when the material gas contained in the reaction gas 122 contains the pretreatment gas 121, the step S16 may be omitted. This step S16 is a step of discharging the pretreatment gas 121 from the chamber 511.

For example, in the case where ammonia gas is used as the pretreatment gas 121, when ammonia gas is contained in the material gas, the above-described step S16 can be omitted. Further, the gas supply source 518 may be configured by only the reaction gas source 182.

In general, a polycrystalline germanium substrate is used as a substrate for a crystalline germanium solar cell. In the polycrystalline germanium substrate, the grain boundary of the polycrystalline germanium becomes a defect. The carrier is trapped by the above-described defects, and the conversion efficiency of the solar cell (hereinafter simply referred to as "conversion efficiency") is lowered.

However, according to the film forming method described above, the hydrogen radicals in the ammonia plasma are combined with the dangling bonds of the substrate 500 by film formation pretreatment. Thereby, the defect is reduced for the carrier, and the passivation effect is increased. As a result, the carrier lifetime of the substrate 500 is prolonged. Therefore, the above method is used to form an antireflection film or a passivation film of a solar cell, whereby conversion efficiency is improved.

FIG. 21 shows a case where the conversion efficiency of the solar cell and the carrier life cycle of the substrate 500 after the film formation are performed, and the plasma film forming apparatus 10 is used to perform the film forming pretreatment and the comparative example in which the film forming pretreatment is not performed. Comparing results. In FIG. 21, the manufacturing method A of the comparative example is a method in which the film forming pretreatment is not performed, that is, steps S12 to S16 of the flowchart shown in FIG. 20 are not performed, and steps S17 to S20 are used. A method of forming a film. On the other hand, the manufacturing method B for performing film formation pretreatment is a manufacturing method according to the flowchart shown in FIG.

In order to measure the conversion efficiency shown in FIG. 21, a sample was prepared in which a tantalum nitride film was formed as an antireflection film of a crystalline lanthanide solar cell. That is, a thin film which is a tantalum nitride film is formed on the substrate 100 which is a polycrystalline germanium substrate. A specific configuration example of the prepared sample is shown in Fig. 22 . Phosphorus (P) is diffused to the surface of the p-type polycrystalline germanium substrate 51 to form an n+ diffusion region, and a tantalum nitride (SiN) film 52 is disposed on the n+ diffusion region. A silver (Ag) electrode 53 is disposed on the tantalum nitride film 52, and an aluminum (Al) electrode 54 is disposed on the back surface of the polysilicon substrate 51. The tantalum nitride film 52 has a refractive index of about 2.0 to 2.15 and a film thickness of about 75 nm to 90 nm. Light was irradiated to the sample shown in FIG. 6, and current-voltage measurement was performed to obtain conversion efficiency.

Further, a sample was prepared as a sample for measuring the carrier life cycle of the substrate 500 after the film formation, and the sample was formed on both surfaces of the n-type single crystal germanium substrate 61 and the solar cell as shown in FIG. The anti-reflection film is similarly formed with tantalum nitride films 62 and 63. By microwave photoconductive decay (μ-PCD) method The sub-life cycle was measured, and the μ-PCD method measures the amount of carriers generated in a sample irradiated with a laser.

As shown in FIG. 21, in the manufacturing method A in which the film formation pretreatment was not performed, the conversion efficiency was 15.09%, and the carrier life cycle of the substrate was 2475 microseconds (μ second). On the other hand, in the manufacturing method B in which the film formation pretreatment was performed, the conversion efficiency was 15.14%, and the carrier life cycle of the substrate was 2808 microseconds. That is, it has been confirmed that the conversion efficiency and the carrier life cycle of the substrate are improved by performing the film formation pretreatment shown in FIG.

Further, the film forming pretreatment of the manufacturing method B is performed by setting the pretreatment gas 121 to ammonia gas, setting the pressure of the pretreatment gas 121 in the chamber 11 to 100 Pa, and exposing the substrate 100 to the ammonia plasma. The processing time was set to 15 seconds, and the power density of the AC power source 14 was set to 83 mW/cm ² .

As described above, in the plasma film forming apparatus 10 according to the embodiment of the present invention, the substrate 100 is exposed to a plasma containing hydrogen before the film forming process, whereby the passivation effect of the substrate 100 is improved. As a result, according to the film forming method using the plasma film forming apparatus 10, the life cycle of the carrier in the substrate 100 is prolonged, and the conversion efficiency of the solar cell can be improved.

In the plasma film forming apparatus 10 of the second embodiment of the present invention, as shown in FIG. 19, the substrate 1 is vertically arranged. In the plasma film forming apparatus 10 shown in FIG. 19, the substrate carrier 512 and the high-frequency electrode 513 are in a comb shape including a plurality of tooth portions, and the plurality of tooth portions face each other in the vertical direction toward the paper surface. The substrate holder 512 and the comb-tooth portion of the high-frequency electrode 513 are arranged to have an interdigitated shape. The substrate 500 is mounted on each of the plurality of tooth portions of the substrate carrier 512 that faces the high-frequency electrode 513, and thus can be disposable. The plurality of substrates 500 are processed.

The groove 532 is formed so that the surface of the tooth portion of the high-frequency electrode 513 includes an opening, and the high-frequency electrode 513 functions as a hollow cathode electrode. In the example shown in FIG. 19, the groove 532 is formed by penetrating the tooth portion of the high-frequency electrode 513. Enclosure of electrons due to the hollow cathode effect is caused in the groove 532, so that high-density plasma is stably generated in a form supplied from the groove 532. As a result, the pretreatment gas 121 or the material gas is efficiently decomposed, and the film formation pretreatment and the film formation treatment can be performed on the plurality of substrates 500 in a short time.

FIG. 24 shows a comparison between the conversion efficiency of the solar cell and the carrier life cycle of the substrate 500 after the film formation, and the film formation pretreatment using the thin film forming apparatus 10 shown in FIG. The comparison result of the case. In FIG. 24, the manufacturing method A of the comparative example is a method in which the film forming pretreatment is not performed, that is, steps S12 to S16 of the flowchart shown in FIG. 20 are not performed, and steps S17 to S20 are used. A method of forming a film. On the other hand, the manufacturing method B for performing film formation pretreatment is a manufacturing method according to the flowchart shown in FIG.

Further, similarly to the case of the comparison shown in FIG. 21, a tantalum nitride film was formed as an antireflection film of a crystalline lanthanide solar cell, and a sample for measuring conversion efficiency was prepared (see FIG. 22). Further, a sample was prepared as a sample for measuring the carrier life cycle of the substrate 500 after film formation, and the sample was formed with tantalum nitride on the both surfaces of the single crystal germanium substrate in the same manner as the antireflection film of the solar cell. Film (see Figure 23).

The film forming pretreatment is carried out under the condition that the pretreatment gas 121 is set to ammonia gas, the pressure of the pretreatment gas 121 in the chamber 511 is set to 67 Pa, and the treatment time for exposing the substrate 500 to the ammonia plasma is set to 5 seconds. The power density of the AC power source 514 was set to 400 mW/cm ² . The hollow cathode electrode is used as the high-frequency electrode 513, whereby the pressure of the pretreatment gas 121 can be lowered to increase the power density.

As shown in FIG. 24, in the manufacturing method A in which the film formation pretreatment was not performed, the conversion efficiency was 16.26%, and the carrier life cycle of the substrate was 526 microseconds. On the other hand, in the manufacturing method B in which the film formation pretreatment was performed, the conversion efficiency was 16.44%, and the carrier life cycle of the substrate was 6751 microseconds. That is, by performing the film formation pretreatment shown in FIG. 20, the conversion efficiency and the carrier life cycle of the substrate are improved.

According to the comparison between FIG. 21 and FIG. 24, it can be said that the film forming apparatus using the hollow cathode discharge is used for the film forming pretreatment using the pretreatment gas 121 as compared with the thin film forming apparatus which does not utilize the hollow cathode discharge and uses the parallel plate type electrode. The effect is even greater.

In one embodiment, the substrate is a solar cell substrate having an n-type semiconductor layer having a surface diffusion concentration of 1×10 ¹⁸ to 1×10 ²² formed on the p-type germanium substrate, or, in an embodiment, A solar cell substrate having a p-type semiconductor layer having a surface diffusion concentration of 1 × 10 ¹⁸ to 1 × 10 ²² is formed on the n-type germanium substrate.

In one embodiment, the thin film formed on the substrate is an antireflection film comprising a tantalum nitride having a refractive index of 1.8 to 3.0 and a film thickness of 50 nm to 150 nm disposed on the solar cell substrate.

The invention also provides a crystalline solar cell, characterized in that it comprises: An antireflection film or a passivation film formed using the plasma film forming apparatus.

As such, the present invention naturally includes various embodiments and the like not disclosed herein. Therefore, the technical scope of the present invention is determined by the above-described description only by the specific matters of the invention of the proper patent application scope.

[Industrial availability]

The plasma film forming apparatus of the present invention can be utilized in the manufacturing of semiconductor devices in which a film is formed on a substrate.

1, 500‧‧‧ substrate

10‧‧‧ Plasma film forming device

11‧‧‧Substrate holder

12, 12A‧‧‧ cathode electrode

13‧‧‧ gas supply device

14, 17, 514 ‧ ‧ AC power supply

15‧‧‧Exhaust device

16‧‧‧ pulse generator

18‧‧‧Power splitter

20, 511‧‧ ‧ chamber

30, 212‧‧‧ support desk

31‧‧‧Introduction hole

51‧‧‧p-type polycrystalline germanium substrate

52, 62, 63‧‧‧ nitride film

53‧‧‧Silver (Ag) electrode

54‧‧‧Aluminum (Al) electrode

61‧‧‧n type single crystal germanium substrate

100‧‧‧Process Gas

110‧‧‧Jacketing surface

111‧‧‧Substrate mounting board

112‧‧‧ fixed board

113‧‧‧ gas introduction hole

120‧‧‧through holes

121‧‧‧Pretreatment gas

122‧‧‧Reactive gas

130‧‧‧ gas supply nozzle

150‧‧‧ venting holes

151‧‧‧1st exhaust adjustment plate

152‧‧‧2nd exhaust adjustment plate

181‧‧‧Pretreatment gas source

182‧‧‧Reactive gas source

200‧‧‧Inline film forming device

210‧‧‧Input/heating room

211‧‧‧heating room

211A‧‧‧heater

211B‧‧‧ slot heater

213‧‧‧ Thermal insulation board

220‧‧‧ Filming room

230‧‧‧Extraction room

240A, 240B, 241‧‧ ‧ gate

401‧‧‧ recess

402‧‧‧ gas outlet

512‧‧‧Substrate carrier

513‧‧‧High frequency electrode

515‧‧‧ gas supply mechanism

516‧‧‧ gas discharge mechanism

518‧‧‧ gas supply source

532‧‧‧ slot

541‧‧‧matcher

I-I‧‧ Direction

S11~S21‧‧‧Steps

Fig. 1 is a schematic view showing a configuration of a plasma film forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view showing an example of a substrate holder used in the plasma film forming apparatus according to the embodiment of the present invention.

3 is a schematic structural view showing an example of a cathode electrode of a plasma film forming apparatus according to an embodiment of the present invention.

4 is a schematic structural view showing an example of a cathode electrode of a comparative example.

FIG. 5 is a schematic view showing an example of a cathode electrode of a plasma film forming apparatus according to an embodiment of the present invention.

FIG. 6 is a schematic view for explaining a method of introducing a process gas in the plasma film forming apparatus of the embodiment of the present invention.

FIG. 7 is a schematic view for explaining a method of arranging a gas supply nozzle in the plasma film forming apparatus according to the embodiment of the present invention.

Figure 8 is a view showing a plasma film forming apparatus according to an embodiment of the present invention; A schematic diagram of a method of mounting a substrate will be described.

FIG. 9 is a schematic view showing a shape example of a gas supply nozzle of the plasma film forming apparatus according to the embodiment of the present invention, and the top view of FIGS. 9(a) to 9(c) is a plan view, and the lower side is shown. The figure is a cross-sectional view along the II direction of the plan view.

FIG. 10 is a schematic view for explaining an exhaust method in the plasma film forming apparatus of the embodiment of the present invention.

Fig. 11 is a schematic view for explaining another exhaust method in the plasma film forming apparatus of the embodiment of the present invention.

FIG. 12 is a schematic view showing a configuration of a plasma film forming apparatus according to a modification of the embodiment of the present invention.

FIG. 13 is a schematic view showing a configuration of a plasma film forming apparatus according to another modification of the embodiment of the present invention.

FIG. 14 is a schematic view showing a configuration of a plasma film forming apparatus according to another modification of the embodiment of the present invention.

FIG. 15 is a schematic view showing a configuration of an example in which a plasma film forming apparatus according to an embodiment of the present invention is applied to a film forming chamber of an in-line film forming apparatus.

Fig. 16 is a schematic view showing a state in which a chamber of a plasma film forming apparatus according to an embodiment of the present invention has a cylindrical shape.

FIG. 17 is a schematic view showing a configuration example of a heating chamber of a plasma film forming apparatus according to an embodiment of the present invention.

FIG. 18 is a schematic view showing a configuration of another example in which a plasma film forming apparatus according to an embodiment of the present invention is applied to a film forming chamber of an in-line film forming apparatus.

FIG. 19 is a schematic view showing a configuration of a plasma film forming apparatus according to a second embodiment of the present invention.

FIG. 20 is a flowchart for explaining a method of forming a thin film using the thin film forming apparatus of the second embodiment of the present invention.

Fig. 21 is a table showing a comparison between a film formed by the film forming apparatus of the present invention and a film formed in a comparative example.

Fig. 22 is a schematic view showing the structure of a sample for measuring conversion efficiency.

Fig. 23 is a schematic view showing the structure of a sample for measuring a carrier life cycle.

FIG. 24 is a table showing a comparison between a film formed by the film forming apparatus according to the second embodiment of the present invention and a film formed in a comparative example.

1‧‧‧Substrate

10‧‧‧ Plasma film forming device

11‧‧‧Substrate holder

12‧‧‧Cathode electrode

13‧‧‧ gas supply device

14‧‧‧AC power supply

15‧‧‧Exhaust device

20‧‧‧ chamber

100‧‧‧Process Gas

110‧‧‧Jacketing surface

111‧‧‧Substrate mounting board

112‧‧‧ fixed board

Claims (19)

A plasma film forming apparatus comprising: a chamber into which a substrate holder is loaded, the substrate holder having a mounting surface, a mounting surface on which the substrate is mounted, the substrate holder including a plurality of substrate mounting plates, and the plurality of substrates Each of the board mounting plates defines the mounting surface as a main surface, and is disposed in parallel with each other, and the cathode electrode is disposed to face the mounting surface, and the mounting surface extends in the chamber in the vertical direction. a gas supply device that introduces a process gas between the substrate holder and the cathode electrode in the chamber; and an alternating current power source that supplies alternating current power between the substrate holder and the cathode electrode to cause the process gas A film is formed between the substrate holder and the cathode electrode, and a film containing a raw material contained in the process gas as a main component is formed on the substrate. The plasma film forming apparatus according to claim 1, wherein the gas supply device introduces the process gas into the chamber from the lower side toward the upper side. The plasma film forming apparatus according to the second aspect of the invention, wherein the gas supply device discharges the process gas toward a bottom portion of the cathode electrode from a gas supply nozzle disposed along a bottom surface of the cathode electrode. The plasma film forming apparatus according to claim 1, wherein the plurality of substrate mounting plates are alternated with the plurality of cathode electrodes The outermost surfaces are arranged so as to be the substrate mounting plates, and the mounting surfaces are defined as surfaces of the substrate mounting plate facing the cathode electrodes. The plasma film forming apparatus according to claim 1, wherein the substrate holder includes: a fixing plate that fixes a bottom portion of each of the plurality of substrate mounting plates, wherein the fixing plate is in a vertical direction The through gas introduction holes are formed between the plurality of substrate mounting plates, and the process gas is introduced between the substrate mounting plate and the cathode electrode through the gas introduction holes. The plasma film forming apparatus according to the first aspect of the invention, wherein the cathode electrode includes a through hole, and the through hole is provided with an opening and is located on a surface facing the mounting surface. The plasma film forming apparatus according to claim 1, wherein the chamber has a cylindrical shape. The plasma film forming apparatus according to claim 1, further comprising: a heating chamber that accommodates the substrate holder before forming the film on the substrate, wherein the heating chamber includes a tank heater, The tank heater is disposed between the plurality of substrate mounting plates, and heats the substrate holder and the substrate mounted on the mounting surface. A plasma film forming apparatus according to claim 1, wherein At least one of the substrate holder and the cathode electrode contains carbon. The plasma film forming apparatus according to the first aspect of the invention, wherein the surface roughness of the cathode electrode has a maximum height of 6.3 S or less. The plasma film forming apparatus according to claim 1, wherein a maximum height of the surface roughness of the substrate holder is 25 S or less. A plasma film forming apparatus for forming a film on a substrate, the plasma film forming apparatus comprising: a chamber for accommodating the substrate; a substrate carrier disposed in the chamber and mounted on the substrate, the substrate The carrier board has a mounting surface, the substrate carrier includes a plurality of board mounting boards, and the plurality of board mounting boards define the mounting surface as a main surface, and are disposed apart from each other and in parallel; and the high frequency electrode is disposed in the cavity The gas supply mechanism supplies the pretreatment gas containing hydrogen or the reaction gas containing the raw material gas of the thin film formed on the substrate to the gas chamber. And an alternating current power source that supplies alternating current power between the substrate carrier and the high frequency electrode, and is excited on the upper surface of the substrate at different stages of the film forming step: a plasma containing the pretreatment gas, Or any of the plasmas containing the above-mentioned source gases. a plasma film forming apparatus according to claim 12, which A groove is formed on a surface of the high-frequency electrode facing the substrate on the substrate carrier. The plasma film forming apparatus according to claim 13, wherein the groove is formed to penetrate the substrate carrier. The plasma film forming apparatus according to claim 13, wherein the pretreatment gas and the plurality of discharge holes through which the reaction gas passes are formed at a bottom portion of the groove formed in the high frequency electrode. Opening. The plasma film forming apparatus according to claim 12, wherein the substrate is a solar cell in which an n-type semiconductor layer having a surface diffusion concentration of 1 × 10 ¹⁸ to 1 × 10 ²² is formed on a p-type germanium substrate. A substrate or a solar cell substrate having a p-type semiconductor layer having a surface diffusion concentration of 1 × 10 ¹⁸ to 1 × 10 ²² is formed on the n-type germanium substrate. The plasma film forming apparatus according to claim 16, wherein the film formed on the substrate has a refractive index of 1.8 to 3.0 and a film thickness of 50 nm to 150 nm disposed on the solar cell substrate. An anti-reflection film comprising tantalum nitride. A crystalline solar cell, comprising: using a plasma film forming apparatus according to claim 12; An anti-reflection film or a passivation film is formed. A semiconductor element comprising: an antireflection film or a passivation film formed using the plasma film forming apparatus of claim 12 of the patent application.