JP5347487B2 - Shower electrode plate and plasma CVD apparatus - Google Patents

Description

  The present invention relates to a shower electrode plate used when a thin film is formed on the surface of a substrate, and a plasma CVD apparatus using the shower electrode plate as a parallel plate cathode electrode.

Thin-film solar cells are considered to become the mainstream of solar cells that generate power using sunlight because they are thin, lightweight, inexpensive to manufacture, and easy to increase in area. In addition to this, demand is expanding for business use and general residential use that are installed on the roofs and windows of buildings.
As a method for manufacturing such a thin film solar cell, there are a roll-to-roll method in which layers are continuously formed on a substrate that moves continuously in each film forming chamber, and a substrate that is simultaneously stopped in each film forming chamber. There is a stepping roll method in which the substrate portion after film formation is sent to the next film formation chamber.

FIG. 5 is a schematic configuration diagram showing a film forming apparatus of a stepping roll film forming system in which a plurality of film forming chambers are provided in a common vacuum chamber and a thin film is formed on one surface of a substrate transported vertically. is there. 6A and 6B are schematic configuration diagrams showing the details of the film forming chamber in FIG. 5, where FIG. 6A shows the substrate transport time, and FIG. 6B shows the film forming time.
The film forming apparatus shown in FIG. 5 houses an unwinding chamber 53 in which an unwinding roll 52 around which a long flexible substrate 51 is wound is housed, and a winding roll 54 around which the flexible substrate 51 is wound up. Between the winding chamber 55 and the unwinding chamber 53 and the winding chamber 55, the flexible substrate 51 is disposed along the conveying direction. The flexible substrate 51 has a metal electrode layer, a photoelectric conversion layer, and a transparent electrode. A film forming chamber 56 as a plurality of independent processing spaces provided for forming a thin film such as a layer is provided.
In such a film forming apparatus, the flexible substrate 51 is unwound from the unwinding roll 52 in the unwinding chamber 53 and is wound on the winding roll 54 in the winding chamber 55. The film is formed in the chamber 56.

In each film forming chamber 56, as shown in FIG. 6, in order to form a thin film on the flexible substrate 51 by a plasma CVD method (plasma chemical vapor deposition method), a shower electrode to which a high voltage high frequency is applied. Parallel plate cathode electrodes (high-frequency electrodes) 57 and anode electrodes (ground electrodes) 58 as plates are arranged to face each other with a space therebetween. A high frequency power source 59 and a gas supply pipe 60 are connected to the cathode electrode 57, and the raw material gas introduced into the gas supply pipe 60 is formed from the surface of the cathode electrode 57 having a number of gas flow holes as a shower electrode. It is supplied to the flexible substrate 51 in the chamber 56 in the form of a shower. In the anode electrode (ground electrode) 58, a heater 58a for heating the flexible substrate 51 is incorporated.
The film forming chamber 56 includes an upper wall body 61 and a lower wall body 62 that are arranged to face the upper and lower sides of the flexible substrate 51 that is intermittently transported and form a box shape. At the time of film formation, as shown in FIG. 6B, the upper wall 61 is lowered, the flexible substrate 51 into which the anode electrode 58 is carried is pressed, and the opening side end of the lower wall 62 is sealed. Contact the member 63. Thus, an airtightly sealed film formation space 65 communicating with the exhaust pipe 64 is formed from the lower wall body 62 and the flexible substrate 51. In this state, by applying a high frequency voltage to the cathode electrode 57, plasma is generated in the film formation space 65, the raw material gas introduced into the gas supply pipe 60 is decomposed, and a thin film is formed on the surface of the flexible substrate 51. Then, film formation is performed.

  By the way, in the film formation apparatus of the plasma CVD method using the shower electrode plate as the parallel plate cathode electrode, the film made of the film formation material is not only on the flexible substrate 51 but also in the film formation chamber 56 at the time of film formation. It adheres to the surface of components such as the shower electrode plate and deposits. This adhered and deposited film has a problem that it causes a film thickness distribution defect during the film forming process, peels or drops off, becomes particles and dust, and the required thin film characteristics are impaired.

  Therefore, conventionally, from the viewpoint of maintaining the quality of the thin film and increasing the maintenance cycle, a cleaning method for periodically removing the shower electrode plate from the plasma CVD apparatus and cleaning the surface of the shower electrode plate has been provided. One of them is a method of performing blasting (for example, Patent Document 1 and Patent Document 2).

JP 2001-260025 A JP 2004-243155 A

  However, the conventional blasting cleaning method described above ejects a mixture of small diameter steel balls, sand, synthetic resin or the like onto the surface of the shower electrode plate to remove unnecessary films attached to the surface of the shower electrode plate. Therefore, there is a problem that debris from the blasting process becomes a residue and enters the material surface layer of the shower electrode plate, and the residue falls off due to a temperature rise during the processing process, causing particle failure.

Moreover, pressure loss to the shower electrode plate occurs due to impact heat or the like due to blasting, and in particular, the opening edge portion of the gas flow hole provided in the shower electrode plate is deformed, the opening area of the flow hole is reduced, and the raw material gas There is a risk of hindering the distribution of When the shower electrode plate subjected to such a blasting process is reused, there is a problem in that a preferable result cannot be obtained because the supply state of the source gas during the film forming process changes.
Furthermore, in the conventional blasting process, it is difficult to sufficiently wash the unnecessary film attached to the surface of the shower electrode plate, so it is necessary to repeat the blasting process many times, and there is a problem in workability. There is a risk that the above-described problems may occur more. In addition, when the shower electrode plate is replaced, the whole of the shower electrode plate must be replaced, which increases the cost.

  The present invention has been made in view of such a situation, and the purpose thereof is to reduce the deformation of the peripheral edge of the gas circulation hole even when blasting is performed to remove an unnecessary film attached to the surface. A shower electrode plate and a plasma CVD apparatus that can secure a gas flow hole opening area, can be used continuously for a long period of time, can increase the dispersion effect of the source gas and increase the flow rate, and can reduce the cost. Is to provide.

  In order to solve the above-described problems of the prior art, the present invention is arranged in a film forming chamber for forming a thin film on the surface of a substrate, and is provided with a gas flow hole for supplying a source gas to the surface of the substrate. In the shower electrode plate, the opening peripheral edge located on the blast processing surface side of the gas flow hole is formed in an inclined surface shape.

Moreover, in this invention, the opening peripheral part which faces the front and back both surfaces of the said gas circulation hole is each formed in the inclined surface shape.
Furthermore, in this invention, the opening peripheral part of the said gas circulation hole is formed in the curved inclined surface shape.
And in this invention, the intermediate part of the inner peripheral wall of the said gas circulation hole is formed in the curved surface which protruded in the direction which mutually approaches.

  On the other hand, the shower electrode plate of the present invention is used as a parallel plate cathode electrode for applying a high-frequency voltage in a plasma CVD apparatus in order to form a thin film on the surface of a substrate by plasma CVD.

  As described above, the shower electrode plate according to the present invention is disposed in a film forming chamber for forming a thin film on the surface of the substrate, and is provided with a gas flow hole for supplying a source gas to the surface of the substrate. And since the opening peripheral part located in the blasting surface side of the said gas circulation hole is formed in the inclined surface shape, even if it performs blasting at the time of cleaning, the deformation | transformation of the opening peripheral part of a gas circulation hole is suppressed small It can be reused without any problems after blasting in a state in which the opening area of the gas circulation hole is secured, and unnecessary films attached to the surface can be surely removed, and can be used continuously for a long time. Become. Moreover, in the shower electrode plate of the present invention, since the opening peripheral edge of the gas flow hole is enlarged, the source gas can be effectively dispersed and supplied, and the required flow rate is increased in a short time. be able to.

Moreover, since the opening peripheral part which faces the front and back both surfaces of the said gas distribution hole is each formed in the inclined surface shape, the shower electrode plate of this invention can prevent generation | occurrence | production of the curvature by a blast process.
Further, in the shower electrode plate of the present invention, the opening peripheral portion of the gas flow hole is formed in a curved inclined surface shape, or the middle part of the inner peripheral wall of the gas flow hole protrudes in a direction approaching each other. Since it is formed on the curved surface, the same effect as the above-described invention can be obtained.

  On the other hand, when the shower electrode plate of the present invention is used as a parallel plate cathode electrode for applying a high-frequency voltage in a plasma CVD apparatus to form a thin film on the surface of the substrate by plasma CVD, A quality thin film can be formed, and a plasma CVD apparatus with excellent production efficiency can be provided.

  Hereinafter, a shower electrode plate and a plasma CVD apparatus according to the present invention will be described in detail based on embodiments thereof with reference to the drawings.

[First Embodiment]
1 is a sectional view of a shower electrode plate according to a first embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a portion A in FIG.
The shower electrode plate 1 according to the first embodiment of the present invention shown in FIG. 1 is a parallel plate that applies a high-frequency voltage in a plasma CVD apparatus to form a thin film on the surface of a flexible substrate by plasma CVD. It is used as a cathode electrode.

  Such a plasma CVD apparatus is configured to perform film formation by a stepping roll method, for example. That is, the plasma CVD apparatus to which the shower electrode plate 1 according to the first embodiment of the present invention is applied is not shown, but, for example, in order from one end side to the other end side, the unwinding chamber, the plurality of film forming chambers, The flexible substrate unwound from the unwinding roll of the unwinding chamber enters each film forming chamber and is temporarily stopped in the film forming chamber to form a film on each surface. Is performed, and is wound around a winding roll in the winding chamber. Therefore, in each film forming chamber, the shower electrode plate 1 as a cathode electrode (high frequency electrode) of the present embodiment and an anode electrode (ground electrode) (not shown) are arranged to face each other with a space therebetween. During film formation, plasma is generated by applying a high frequency voltage to the shower electrode plate 1 with the anode electrode holding the flexible substrate and forming a film formation space, and supplied source gases (for example, silane and hydrogen). The Si compound gas) is decomposed to form a thin film on the surface of the flexible substrate, and film formation is performed.

As shown in FIG. 1, the shower electrode plate 1 according to the first embodiment of the present invention has a gas dispersion space forming portion 2 through which a source gas G is introduced, and the source gas G of the gas dispersion space forming portion 2 flows out from the surface. The shower head 3 is periodically removed from the plasma CVD apparatus, and unnecessary films attached to the surface are removed and cleaned by blasting.
The gas dispersion space forming portion 2 is formed in a substantially U-shaped cross section having an opening on one side, and a gas dispersion space 4 for uniformly dispersing the supplied source gas G is provided inside the recess. ing. A gas supply pipe 5 that guides the source gas G to the gas dispersion space 4 is provided on the other side of the gas dispersion space forming unit 2, and the tip of the gas supply pipe 5 communicates with the gas dispersion space 4. The base end of the gas supply pipe 5 is connected to a gas supply source (not shown). The shower electrode plate 1 is connected to a high frequency power source (not shown) as in the conventional example shown in FIG.

  As shown in FIGS. 1 and 2, the shower head 3 has a rectangular flat plate in plan view having a large number of small gas flow holes 6 so that the source gas G in the gas dispersion space 4 flows out in a shower shape. These gas flow holes 6 are disposed so as to penetrate in a pattern (an arbitrary pattern is possible) in which adjacent small hole rows are located, for example.

  In the gas flow hole 6 according to the first embodiment of the present invention, the opening peripheral edge located on the blasting surface side is formed into an inclined surface by a general machining method to form an inclined surface portion 6a. Moreover, in the shower electrode plate 1 of the present embodiment, since the blasting surfaces are both front and back surfaces, the peripheral edge portions of the openings facing both the front and back surfaces are inclined surface portions 6a. In addition, these inclined surface portions 6a have a larger dimension than the diameter of the gas flow hole 6, and are formed in a trapezoidal cross section that gradually expands linearly toward the front and back surfaces.

  Thus, in the shower electrode plate 1 of 1st Embodiment of this invention, since the opening peripheral part of many gas circulation holes 6 provided in the shower head 3 becomes the enlarged inclined surface part 6a, surface Even when the unnecessary film adhering to the gas is repeatedly removed several times by blasting, it is possible to suppress the deformation of the peripheral edge of the opening of the gas flow hole 6, and it can be reused without any problem and unnecessary. The film can be removed reliably. Moreover, in the shower electrode plate 1 of this embodiment, since the opening peripheral part of the gas circulation hole 6 is expanding outward, the source gas G introduced into the gas dispersion space 4 is effectively dispersed. be able to. Therefore, when the shower electrode plate 1 of this embodiment is used as a parallel plate cathode electrode in a plasma CVD apparatus, a high-quality thin film can be formed.

[Second Embodiment]
FIG. 3 is a shower electrode plate according to a second embodiment of the present invention, and is an enlarged cross-sectional view of part A in FIG.
In this 2nd Embodiment, the opening peripheral part of the gas circulation hole 6 is formed in the curved inclined surface shape, and becomes the curved inclined surface part 6b.
Other configurations and operational effects are the same as those of the first embodiment.

[Third Embodiment]
FIG. 4 is a shower electrode plate according to a third embodiment of the present invention, and is an enlarged cross-sectional view of part A in FIG.
In this 3rd Embodiment, while the intermediate part of the inner peripheral wall of the gas distribution hole 16 is formed in the curved surface which protruded in the direction which mutually approaches, the opening peripheral part becomes the inclined surface part 16a which curved.
Other configurations and operational effects are the same as those of the first embodiment.

  While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical idea of the present invention.

  For example, in the embodiment described above, the opening peripheral portions of the gas flow holes 6 and 16 facing both the front and back surfaces of the shower electrode plate 1 are the inclined surface portions 6a, 6b, and 16a, respectively, but the blasting surface is one surface. In this case, only the peripheral edge portions of the gas flow holes 6 and 16 facing the surface on one side may be inclined surfaces 6a, 6b and 16a. In the above-described embodiment, the stepping roll type plasma CVD apparatus is used. However, a roll-to-roll type plasma CVD apparatus may be used. Furthermore, in the above-described embodiment, the shower electrode plate is applied to the plasma CVD apparatus, but may be applied to a thermal CVD apparatus or the like.

It is sectional drawing which shows the shower electrode plate which concerns on 1st Embodiment of this invention. It is sectional drawing which expands and shows the A section in FIG. It is a shower electrode plate which concerns on 2nd Embodiment of this invention, Comprising: It is sectional drawing which expands and shows the A section in FIG. It is a shower electrode plate which concerns on 3rd Embodiment of this invention, Comprising: It is sectional drawing which expands and shows the A section in FIG. It is a schematic block diagram which shows an example of the conventional thin film apparatus of the conventional stepping roll system. 5A and 5B show details of a film forming chamber of the general thin film apparatus shown in FIG. 5, where FIG. 5A shows the time of substrate transfer, and FIG. 5B shows the time of film formation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shower electrode plate 2 Gas dispersion space formation part 3 Shower head 4 Gas dispersion space 5 Gas supply pipe 6,16 Gas flow hole 6a, 6b, 16a Inclined surface part G Source gas

Claims (5)

  In a shower electrode plate disposed in a film forming chamber for forming a thin film on the surface of the substrate and provided with a gas flow hole for supplying a source gas to the surface of the substrate, on the blasting surface side of the gas flow hole A shower electrode plate, wherein an opening peripheral edge portion is formed in an inclined surface shape.   2. The shower electrode plate according to claim 1, wherein opening peripheral portions facing both front and back surfaces of the gas flow hole are each formed in an inclined surface shape. 3. The shower electrode plate according to claim 1, wherein an opening peripheral edge portion of the gas flow hole is formed in a curved inclined surface shape. The shower electrode plate according to any one of claims 1 to 3, wherein an intermediate portion of the inner peripheral wall of the gas circulation hole is formed on a curved surface protruding in a direction approaching each other.   The shower electrode plate according to any one of claims 1 to 4, wherein the shower electrode plate is used as a cathode electrode of a parallel plate for applying a high-frequency voltage so as to form a thin film on the surface of the substrate by a plasma CVD method. A plasma CVD apparatus.

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