JP2012028682A - Plasma device and method of producing semiconductor thin film by using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plasma device in which a large substrate can be processed stably even in a frequency region of a VHF band by minimizing ground impedance.SOLUTION: A plasma device comprises a stage moving mechanism which adjusts the interval of a stage and a shower plate, and a conductive current-carrying member which short-circuits the periphery of the stage and the inner wall surface of a vacuum chamber adjacent thereto out of a ground path from the stage to ground means. The current-carrying member has an electric contact which slides along the movement of the stage, and the electric contact is shielded from the plasma of gas generated between the shower plate and a substrate by high frequency power.

Description

  The present invention relates to a plasma etching apparatus, a plasma CVD apparatus for forming a thin film such as silicon on a substrate at high speed, and a thin film manufacturing method.

  A plasma CVD (Chemical Vapor Deposition) apparatus is widely used as an apparatus for forming a thin film such as an amorphous silicon thin film or a microcrystalline silicon thin film on a substrate. Today, for example, a plasma CVD apparatus capable of forming a large-area thin film at high speed, which is necessary for a power generation layer of a thin film silicon solar cell and a thin film transistor for pixel control of a flat display panel, is used for mass production. ing. In order to form a silicon thin film having a large area as described above, a parallel plate type plasma CVD apparatus is generally used.

A parallel plate type plasma CVD apparatus is a film forming apparatus that generates a high-frequency plasma discharge between a pair of parallel plate electrodes. Usually, a deposition target substrate is mounted and fixed in a chamber that can be evacuated (hereinafter referred to as a vacuum chamber). And a shower head electrode facing each other with a distance of several mm to several tens of mm from the stage. The shower head electrode is provided with a large number of apertures serving as gas supply ports, and is also called a shower plate. Here, the name of the shower plate will be used hereinafter. In order to ensure the quality of the thin film, the shower plate and the stage have a structure in which the mutual positional relationship is maintained. When a silicon thin film is formed, a film forming gas such as silane (SiH ₄ ) or hydrogen (H ₂ ) is supplied to the gap between electrodes serving as a discharge space through the aperture of the shower plate. The gas supplied to the discharge space becomes plasma by high-frequency power and forms a high-frequency discharge. The impedance is appropriately adjusted so as to stably maintain this discharge state. The deposition gas is decomposed into high-energy radicals in the plasma, and is incident on the deposition substrate to form a silicon film on the substrate. In order to transport the substrate onto the stage and to carry it out of the stage, a moving mechanism is often provided that moves the stage up and down while maintaining parallel to the shower plate surface.

  Patent Document 1 describes a problem related to plasma stability caused by the skin effect of high-frequency ground current. The skin effect is a phenomenon in which when the frequency of the current flowing through the conductor increases, the current flows concentrated on the layer on the very surface of the conductor. Can only propagate. That is, the high-frequency ground current returns to the power source through a path along the inner wall surface of the vacuum chamber, which is a conductor, instead of a path that directly penetrates the conductor as in the case of a low frequency.

  In the plasma apparatus, when the stage is grounded, a relatively long path from the back of the stage along the inner wall of the vacuum chamber is taken, so that the so-called ground impedance generated by the resistance, inductance, capacitance, etc. of the ground path itself increases. . When the ground impedance is high, various problems occur, such as an unexpected potential being induced on the stage and abnormal discharge occurring outside the deposition chamber. As a result, the plasma on the deposition target substrate is unaffected. It becomes stable. The film forming characteristics (film forming speed, film physical properties, etc.) of the plasma CVD apparatus strongly depend on plasma parameters such as the electron temperature and the electron density. Therefore, if the plasma is unstable, the film forming characteristics are greatly non-uniform. In particular, it is known that when the deposition target substrate is as large as about 1 m, the apparatus becomes large, and this problem becomes apparent. Patent Document 1 discloses a method using a ground strap as a current-carrying member that connects a stage and a vacuum chamber as a countermeasure.

  Patent Document 2 discloses a method of providing a plate member as a current-carrying member over the entire outer periphery of the stage in order to shorten the ground path and reduce the ground impedance. In order to secure the grounding path, it is necessary to correspond to the lifting mechanism described above, so a method is used in which a flexible plate member having both ends fixed to the outer periphery of the stage and the vacuum chamber is deformed as the stage moves. ing.

  In Patent Document 3, a contact finger is attached as a current-carrying member between a periphery of a lifting unit provided at a lower portion of a stage connected to a high-frequency power source and a vacuum chamber, and the lifting unit and the vacuum chamber are connected by a sliding mechanism of the contact finger. A method for achieving electrical connection is disclosed.

  In Patent Document 4, in order to shorten the installation path, a method is shown in which a block or frame in which a flexible curtain-like member is connected as a current-carrying member to the vacuum chamber side is lifted at the outer periphery of the stage and connected. It is possible to raise and lower the stage within the range that the curtain-like member follows in the grounding state.

JP 2008-274437 A JP 2008-244079 A JP-A-6-333879 JP 2009-280913 A

  In many cases, a robot hand disposed outside a vacuum chamber, for example, in a load lock chamber, is used for transporting and unloading a film formation substrate. Usually, a substrate is supported by pins, a gap is formed between the stage and the substrate, and an arm of a robot hand is inserted into the gap to convey and carry the substrate. For this reason, when using a large film deposition substrate of the metric class such as a thin film silicon solar cell or a glass substrate for a flat panel display, the robot hand inevitably becomes large, and the stage is on the order of several hundred mm. It is necessary to move up and down. There may also be a case where it is necessary to secure a space for cleaning the vacuum chamber.

  Therefore, in the plasma film forming apparatus described in Patent Document 2, it is necessary to design the shape of the plate member in anticipation of the movable range of the stage so that the plate member on the ground path does not hinder the lifting operation of the stage. It was. That is, in the configuration of Patent Document 2, the length of the plate member must be designed to be longer than the lift range of the stage, that is, several hundred mm. This is one digit or more longer than 10 mm to 50 mm, which needs to be raised and lowered as a process parameter, which is a disadvantageous method in terms of minimizing the ground impedance, and has been a design constraint.

  Conventionally, even in the configuration as described above, there has been little problem when plasma is generated using high frequency power of 13.56 MHz having a relatively low frequency. However, when using high frequency power in the VHF (very high frequency) band, which has a higher frequency in order to increase the deposition rate and increase the throughput, the skin effect becomes prominent, and the ground impedance problem becomes extremely serious. Become. For example, in the impedance of the ground strap, the resistance component increases in proportion to the square root of the frequency due to the skin effect, and the inductive component increases in proportion to the frequency. Therefore, when the frequency of the high frequency power is increased from 13.56 MHz to 60 MHz, the ground impedance increases at least twice or more by simple calculation.

  This has the same result as configuring the ground path twice as long using the same high frequency power of 13.56 MHz. That is, the effect of bypassing the path from the stage to the vacuum chamber using a grounding strap or the like is offset, and a problem regarding stabilization of plasma generation becomes obvious. As an example, when a parallel plate type plasma film forming apparatus configured to have a grounding path to the vacuum chamber of 400 mm was used and plasma generation was attempted by applying high frequency power of 60 MHz, stable discharge was generated in the electrode gap. It was very difficult to get.

  In the plasma apparatus described in Patent Document 4, since the stage is not connected to the vacuum chamber in a state where the stage is lowered to carry in and out the substrate, there is no restriction on the moving range of the stage. There are no design constraints as with plate members. However, it is difficult to ensure a uniform contact state over the entire outer periphery of the stage by simply lifting the block or frame on the stage. Furthermore, when used for film formation, a film is also deposited on the outer peripheral portion by the film formation process, so that there is a problem that reproducibility cannot be obtained for the impedance of each film formation batch in which the substrates are replaced. Therefore, it has been difficult to avoid the problem that plasma is generated unstable or non-uniformly at a frequency in the VHF band where the influence of the ground impedance is particularly large.

  In addition, the use of a flexible member near the plasma space where the film is actually formed means that the coating deposited on the film cracks and scatters, and is placed on the film formation substrate, causing problems, It was a factor that decreased the yield because it floated in the air and disturbed the plasma.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a plasma apparatus that can stably perform processing on a large substrate even in the frequency region of the VHF band by minimizing the ground impedance.

  In order to solve the above-described problems and achieve the object, a plasma apparatus according to the present invention includes a conductive vacuum chamber, a shower plate having a gas supply port installed insulated from the vacuum chamber, and a shower plate. A stage on which a substrate placed opposite to the substrate is mounted, means for supplying high frequency power to the shower plate, means for grounding the vacuum chamber, and stage movement for adjusting the distance between the stage and the shower plate by moving the stage A mechanism and a conductive energization member that is fixed to the outer periphery of the stage and short-circuits between the outer periphery and the vacuum chamber. The energization member forms an electrical contact that slides along the movement of the stage. The electrical contact is configured to be shielded from plasma of gas generated between the shower plate and the substrate by high-frequency power.

  A large-area substrate is formed by using plasma discharge in the VHF frequency band by fixing an energizing member on the outer periphery of the stage and forming an electrical contact that swings along the movement of the stage and shielding the electrical contact from the plasma. Can be stably performed.

It is sectional drawing which shows roughly the structure of the plasma apparatus in Embodiment 1 of this invention. It is a top view which shows the arrangement method of the contact finger in Embodiment 1 of this invention. It is a fragmentary sectional view which shows schematically the structure of the plasma apparatus in Embodiment 1 of this invention. It is a fragmentary sectional view which shows schematically the structure of the plasma apparatus in Embodiment 2 of this invention. It is a fragmentary sectional view which shows schematically the structure of the plasma apparatus in Embodiment 3 of this invention. It is a perspective view which shows the structure of the contact finger in Embodiment 3 of this invention. It is a top view which shows the structure of the contact finger in Embodiment 3 of this invention. It is a fragmentary sectional view which shows roughly the structure of the plasma apparatus in Embodiment 4 of this invention.

  Embodiments of a plasma CVD apparatus according to the present invention will be described below in detail with reference to the drawings.

Embodiment 1.
FIG. 1 is a cross-sectional view schematically showing a configuration of a first embodiment of a plasma apparatus according to the present invention. A plasma apparatus 100 illustrated in FIG. 1 includes a vacuum chamber 101, a stage 121 having a moving mechanism, a shower plate 122 having a large number of gas supply ports, a power supply bar 113, and a high-frequency power source 111. Further, a contact finger 141 serving as a current-carrying member for the grounding path is provided on the outer periphery of the stage 121.

  The vacuum chamber 101 is hermetically sealed between the lower flange 102 and the lower flange 102 and the upper flange 103 to separate the inside from the atmosphere. The lower flange 102 and the upper flange 103 form an opening parallel to the substrate mounting surface of the stage 121 and the shower plate 122, and can be regarded as a part of the vacuum chamber 101 as a configuration. Insulating spacers 132 and 133 are joined to the upper flange 103, and the insulating spacers fix the electrode block 123. These structures constitute a decompression vessel including a stage 121 and a shower plate 122 therein, and a space between the stage 121 and the shower plate 122 is a plasma space 160 in which high-frequency plasma is generated. Above the electrode block 123 is an atmospheric pressure region.

  Further, the vacuum chamber 101 has an exhaust port 106 and a gate valve 104. The inside of the decompression vessel is evacuated from an exhaust port 106 provided in the chamber 101 by a vacuum pump (not shown). The vacuum chamber 101 is usually made of a metal such as an aluminum alloy and has good electrical conductivity. The stage 121 is supported by support columns 124, and the deposition target substrate 170 is placed on the stage 121. By connecting the column 124 to a drive mechanism (not shown), the stage 121 can be moved up and down.

  A gate valve 104 is provided in the vacuum chamber 101, and the deposition target substrate 170 is transferred onto the stage 121 through the gate valve 104. With the film formation substrate 170 mounted on the stage 121, the support column 124 and the stage 121 rise and approach the shower plate 122. The distance between the stage 121 and the shower plate 122 is adjusted to a desired value, and then high frequency power is supplied to generate plasma. After the plasma processing such as film formation and etching is completed, the support column 124 and the stage 121 are lowered and moved away from the shower plate 122, and the deposition target substrate 170 passes through the gate valve 104 and goes out of the vacuum chamber 101 from the stage 121. It is carried out.

  The electrode block 123 supports the shower plate 122, is electrically connected to the shower plate 122, and is connected to the power supply bar 113. The electrode block 123 is joined to the insulating spacer 133 and is further insulated from the upper flange 103 via the insulating spacer 132. A shield box 180 surrounding the electrode block 123 is provided above the electrode block 123, and the shield box 180 is insulated from the power supply bar 113 by an insulating spacer 131.

  In addition, a plasma generation gas introduction pipe is provided from the electrode block 123 through the shield box 180 and has a film forming gas supply port 105 connected to an external gas supply facility. The shield box 180, the vacuum chamber 101, the lower flange 102, and the upper flange 103 are all connected to the ground side of the high-frequency power supply 111 to prevent electric shock and radiation noise.

Next, the high frequency power feeding unit will be described in detail. The VHF band is selected as the frequency of the high-frequency power source 111 in order to realize high-speed film formation. In order to supply high-frequency power in the VHF band to a large-area electrode, a method of feeding power from a plurality of locations is preferable in order to reduce the influence of standing waves. Although the number of power feeding locations is selected depending on the size and structure of the apparatus, the effect of the present invention does not depend on the number of power feeding locations, so FIG. 1 illustrates a case where high frequency power feeding is performed from one power source.
The high frequency power supply unit includes a high frequency power supply 111, a power supply bar 113, and a matching unit 112. The high-frequency power output from the high-frequency power source 111 is normally transmitted via a coaxial cable feed line, and is supplied to the feed bar 113 through the matching unit 112. The power feeding bar 113 has a role of transmitting high-frequency power transmitted from the matching unit 112 to the electrode block 123. The power supply bar 113 is made of a material having high conductivity such as copper or aluminum, and is fixed to the electrode block 123 with screws or the like. The high-frequency current flows in a very shallow portion near the surface of the electrode block 123 due to the skin effect, and is similarly supplied to the surface portion of the shower plate 122.
The outer conductor of the coaxial cable serving as the ground potential of the high-frequency power source 111 is connected to the casing of the matching unit 112 or the shield box 180 in the vicinity thereof.

Next, the grounding means constituting the high-frequency current feedback path will be described. In the present embodiment, a contact finger 141 is used as an energizing member for grounding the stage 121. The contact finger 141 is fixed to the outer peripheral portion of the stage 121 close to the substrate mounting surface, and the substantially semicircular arc-shaped portion slides on the inner wall surface of the chamber 101 connected to the ground side of the high frequency power supply 111 along the movement of the stage 121. It is possible to move. That is, the contact portion between the contact finger 141 and the vacuum chamber 101 forms an electrical contact, and even when the stage 121 moves up and down, this electrical contact is maintained and electrical connection between the stage 121 and the vacuum chamber 101 is ensured. is doing. Therefore, the ground path is configured to reach the ground side of the high-frequency power source 111 via the stage 121, the lower portion of the vacuum chamber 101, the lower flange 102, the upper flange 103, and the shield box 180.
A configuration in which the contact finger 141 substantially short-circuits the outer periphery of the stage 121 and the vacuum chamber 101 in the vicinity thereof in the ground path from the stage 121 to the high-frequency power supply 111 via the column 124 and the lower portion of the vacuum chamber 101. As a result, the ground impedance of the stage 121 can be greatly reduced. Specifically, the back surface of the stage 121, the support column 124, and the lower path of the vacuum chamber 101 deviate from the main grounding path. By reducing the ground impedance, unnecessary discharge is prevented from occurring between the stage 121 outside the plasma space 160 and the vacuum chamber 101, and the plasma can be stably maintained even when using high-frequency power in the VHF band.

  With respect to the sliding electrical contact, if the moving direction of the inner surface of the vacuum chamber 101 and the stage 121 is substantially parallel, the connection state on the inner wall surface of the chamber 101 will change even if the stage 121 moves. Absent. FIG. 2 is a plan view showing the arrangement method of the contact fingers. In order to minimize the ground impedance, the contact fingers 141 are preferably arranged so as to cover the outer periphery of the stage 121 as shown in FIG. The planar shape of the vacuum chamber 101 is generally a square or a rectangle, but in the case of a circle, the contact portion on which the contact finger 141 slides is a curved surface.

  The contact finger 141 is made of an electrically conductive material having elasticity. For example, an aluminum alloy, Inconel (registered trademark), Hastelloy (registered trademark), or a metal plate made of an alloy containing tungsten or tungsten is preferable. Depending on the material of the metal plate, it may react with the type of film forming gas to be used and the gas used for etching cleaning inside the plasma space 160, so the material must be selected as appropriate.

  FIG. 3 is a cross-sectional view showing details of the periphery of the contact finger 141 and corresponds to a portion indicated by a two-dot chain line in FIG. The contact finger 141 is fixed to the stage 121 using a screw member 142 and a pressing member 143. It is also possible to use a plate-like energizing member 107 that is not shown in FIG. 1 and that contacts the contact finger 141 on the inner wall surface of the vacuum chamber 101 to form an electrical contact. The plate-like energizing member 107 is another energizing member for grounding which is paired with the contact finger 141. When the vacuum chamber 101 is made of an aluminum alloy that is easily worn by sliding, an electrical contact is made by using a material that does not easily wear. Can improve the service life. Actually, a material similar to that of the contact finger 141 may be used. The size of the plate-like energizing member 107 is set in consideration of the position range of the stage 121 that uses high frequency discharge in the moving direction of the stage 121.

  Further, since the contact finger 141 also acts as an electrical shield member, unnecessary radiation of high-frequency power to the outside of the plasma space 160 can be suppressed. In order to obtain a sufficient radiation suppression effect, the distance between the contact fingers 141 needs to be sufficiently short with respect to the wavelength of the high frequency power. Specifically, it is preferable that the interval does not exceed 1/100 of the wavelength, which corresponds to 5 cm at a high frequency of 60 MHz. Even in the case where a slit is provided in the contact finger 141 itself so as not to disturb the gas flow, it is desirable that the size of the slit is similarly made sufficiently smaller than the wavelength.

  Next, problems associated with fixing the contact finger 141 to the outer peripheral portion close to the substrate mounting surface of the stage 121 will be described.

  Usually, in the plasma CVD apparatus, a film is deposited on the inner wall of the chamber 101 and the stage 121 near the plasma space 160 other than the deposition target substrate 170. When these films are deposited thick by repeating the film formation process, they are finely cracked, separated into small pieces, and scattered as particles in the film formation chamber. When these particles reach the film formation substrate 170 side, the characteristics of a device manufactured using the plasma film forming apparatus are often greatly affected. For example, if it remains on the thin film, it becomes a defect of the film structure, and even floating in the plasma space 160 causes disturbance of the high-frequency plasma, resulting in non-uniform film quality.

  Therefore, when an electrical contact that slides to a position close to the plasma space 160 is used, a film is deposited on the inner wall surface of the chamber 101 and the contact finger 141, and the film on the inner wall surface of the chamber 101 is scraped off when sliding. In addition, it is necessary to consider that the film peels off when the contact finger 141 is bent and deformed.

  In order to cope with this problem, as shown in FIG. 3, a protection plate 151 on the stage 121 side and a protection plate 152 on the upper flange 103 side are used at positions where the sliding portion is shielded from the plasma space 160. The method is appropriate. The protection plates 151 and 152 each have a pair of shielding surfaces that are substantially parallel to the inner wall surface of the vacuum chamber 101 from the upper flange 103 and the stage 121 side, and are arranged so as to overlap each other when viewed from the plasma space 160. Thus, the electric contact of the sliding portion is double shielded from the plasma space 160. The deposition plates 151 and 152 can prevent the active species generated by the high-frequency plasma from reaching the inner wall surface of the vacuum chamber 101 and the contact finger 141, thereby suppressing film deposition. Can be suppressed. Further, even if a film is deposited on the inner wall surface of the vacuum chamber 101 and the contact finger 141 and particles composed of film pieces are scattered, the adhesion preventing plates 151 and 152 prevent the particles from entering the plasma space 160. Can do. In particular, the deposition preventing plate 151 is important for preventing particles from entering the stage 121 because the particles fall to the vacuum pump side after the particles collide.

  By using the plasma CVD apparatus having the above-described configuration, it is possible to carry in and out the substrate after the stage has moved downward, and to uniformly, rapidly and stably form a large area thin film after the stage has moved upward. A film can be formed.

  The adhesion preventing plates 151 and 152, the plate-like energizing member 107, and the contact finger 141 are fixed so as to be removable, so that the removed and deposited film is removed and then installed again or replaced with a new member. This has the advantage of making maintenance work more efficient. When the contact finger 141 is fixed on the substrate mounting surface of the stage 121, the stage 121 is lifted with the flange opened and the vacuum chamber 101 opened to the atmosphere, and the contact finger 141 is exposed outside the vacuum chamber 101. Maintenance work such as replacement of the contact finger 141 can be performed efficiently.

  In FIG. 1, the contact finger 141 is fixed on the stage 121 side, but it can also be fixed on the inner wall surface of the vacuum chamber 101. In that case, the plate-like energizing member 107 can be fixed to the outer periphery of the stage 121. When a material softer than the contact finger is used for the plate-like energizing member 107, the plate-like energizing member 107 may be periodically replaced in order to prevent contact failure due to wear.

In order to form a silicon thin film on the deposition target substrate 170, for example, monosilane (SiH ₄ ) gas is used as a silicon source, hydrogen (H ₂ ) gas is used as a carrier gas, and a mixed gas for plasma generation is used. Used as a film forming gas. The film forming gas is supplied into the electrode block 123 through the gas supply port 105, and flows into the plasma space 160 on the opposite stage 121 through the many apertures 125 formed in the shower plate 122. High frequency power is supplied to the electrode block 123, and the deposition gas in the plasma space 160 is decomposed by the high frequency power to generate high frequency plasma. In this process, active species such as SiH ₃ , SiH ₂ , SiH, Si, and H are generated, and these active species enter the deposition target substrate 170, and are amorphous or microcrystalline on the deposition target substrate 170 surface. The silicon is formed. As a result of continuing the high-frequency plasma for a certain time, an amorphous or microcrystalline silicon thin film is formed on the deposition target substrate 170.

Hereinafter, an experiment in which high-frequency plasma is generated with a mixed gas of silane gas (SiH ₄ ) and hydrogen gas (H ₂ ) using the apparatus shown in FIGS. 1 to 3 to deposit a microcrystalline silicon film on a glass substrate. explain.
A 1400 mm × 1100 mm glass substrate (thickness: 4 mm) was placed on the stage 121 in the evacuated vacuum chamber 101 as the film formation substrate 170 and heated to 200 ° C. using a sheath heater built in the stage 121. Next, the height position of the stage 121 was set so that the distance between the electrode block 123 and the deposition target substrate 170 was 5 mm. In this state, SiH ₄ gas and H ₂ gas were supplied to the film forming gas supply port 105 at flow rates of 1 slm and 50 slm, respectively, and the exhaust speed was adjusted so that the gas pressure in the plasma space 160 was 1000 Pa. After the gas pressure was stabilized, high frequency power of 60 MHz was supplied to the shower plate 122 side to generate a SiH ₄ / H ₂ mixed plasma, and film formation was performed for 20 minutes with 20 kW of high frequency power supplied.

When the film forming experiment of the silicon thin film was performed using the apparatus shown in FIG. 1, the in-plane film thickness distribution was within a range of ± 6% with respect to the average film thickness of 2 μm. Assuming that the prepared thin film is used for solar cells, the formation ratio of crystalline silicon was investigated by Raman spectroscopy. A sufficient peak intensity ratio was obtained, and the in-plane uniformity of the above formation ratio was within the practical range. I was able to confirm that there was. From this, it was concluded that a silicon film having excellent characteristics can be formed even with a practical substrate size.
On the other hand, when the configuration using the ground strap disclosed in Patent Document 1 is used, when a silicon thin film having a film thickness of 1 μm is formed under the same conditions, the in-plane film thickness distribution is within ± 38% of the average value. As a result, the practicality was low.

In the present embodiment, numerical values are shown for parameters such as gas flow rate, pressure, and high frequency power, but these numerical values can be changed as appropriate. Further, the description has been given of the mixed gas of SiH ₄ and H ₂ as the film forming gas for forming a silicon thin film, further, Ar, may be added to rare gas Ne, and the like. In addition, an appropriate gas type is selected according to the purpose of the process.

Embodiment 2.
FIG. 4 is a partial cross-sectional view of the plasma apparatus 100 schematically showing the configuration of the second embodiment using sliding electrical contacts. FIG. 4 shows a contact finger 144 having a shape that is fixed to the outer periphery of the stage 121 on the mounting surface of the film formation substrate 170 and is bent at a substantially right angle toward the shower plate 122 as an energization member for grounding. . A portion that is bent at a substantially right angle and extends upward has a flat portion facing the inside of the plasma space 160.

Compared with the contact finger 141 of the first embodiment, the contact finger 144 of the present embodiment provides the following new effects (1) to (3).
(1) Since the substantially semicircular arc-shaped sliding portion approaches the shower plate 122 side, the electrical contact approaches the power supply line side as a result, so that the ground impedance is further reduced.
(2) Since the flat portion facing the plasma space 160 side also functions as an adhesion preventing plate, the adhesion preventing plate 151 on the stage 121 side can be omitted. By using in combination with the deposition preventing plate 152, the generated particles can be dropped almost completely to the pump side.
(3) Since there is a fixing part on the upper surface of the stage 121, the vacuum chamber 101 is opened with the upper and lower flanges, and removal and attachment in a state where the atmosphere is released to the atmosphere becomes easy.

  From the viewpoint of mechanical design, it is preferable that the bent portion of the contact finger 144 has an arcuate cross-sectional shape having a certain radius of curvature. As a result, the stress of the bent portion can be dispersed and the reliability as a leaf spring can be improved.

  As shown in FIG. 4, also in this embodiment, if the plate-like energizing member 107 is used on the inner wall surface of the vacuum chamber 101, the inner wall surface of the vacuum chamber 101 can be prevented from being worn.

  As for the fixing portion of the contact finger 144, the outer edge portion of the stage 121 may be covered with an insulating cover 154 as shown in FIG. The insulating cover 154 can have a flat surface by concealing the convex shape of the fixing portion of the contact finger 144, thereby removing the influence on the plasma. In addition, if the thickness is set to be substantially the same as that of the deposition target substrate 170, an effect of alleviating film nonuniformity on the outer periphery of the deposition target substrate 170 can be expected.

  Therefore, by using the plasma CVD apparatus having the above-described configuration, it is possible to carry in and out the substrate with the stage moving, and to form a large-area thin film uniformly, at high speed and stably.

Embodiment 3.
FIG. 5 is a partial cross-sectional view of the plasma apparatus 100 schematically showing the configuration of the third embodiment using sliding electrical contacts. In this embodiment, a contact finger 145 is used which is fixed to the surface of the stage 121 on the side where the film formation substrate 170 is mounted and the vacuum chamber 101 side portion protrudes toward the shower plate 122 side. The plate-like energizing member 108 fixed to the vacuum chamber 101 side is an energizing member that contacts the sliding portion of the contact finger 145 to form an electrical contact. An adhesion preventing plate 109 is provided on the stage 121 side of the plate-like energizing member 108.

  For example, the contact finger 145, which is a current-carrying member for grounding, has a shape as shown in the perspective view of FIG. A curved surface curved in a substantially semicircular arc shape that slides in the same manner as the contact finger of the first embodiment and the second embodiment, and the hole 203 for fixing through the screw 142 through the pressing member 143. It has a T-shaped slit 202 into which the part 201, the plate-like energizing member 108 and the deposition preventing plate 109 are inserted.

  FIG. 7 is a plan view showing a state in which the plate-like energizing member 108 and the plate-shaped adhesion preventing plate 109 are inserted into the contact finger 145 and the curved surface portion 201 and the plate-like energizing member 108 are in contact with each other. The plate-like energizing member 108 is on the inner wall surface of the vacuum chamber 101, e.g., standing vertically to the inner wall surface of the vacuum chamber 101, and the sliding surface is parallel to the moving direction of the stage 121. The plate-like deposition preventing plate 109 is fixed in a direction intersecting with the surface of the plate-like energizing member 108 so that the plate surface is a flat surface facing the inside of the plasma space 160, and the cross section is substantially T-shaped. It is integrated with. The sliding surface of the contact finger 145 is composed of two planes facing each other that form the front and back surfaces of the plate-like energization member 108, and each plane contacts the curved surface portion 201 to form an electrical contact. The action of shortening the grounding path is the same as in the second embodiment.

  By adopting the structure as described above, the sliding surface on the plate-like energization member 108 is positioned in parallel to the direction facing the vacuum chamber 101 side from the plasma space 160 side, and further, the plasma space is formed by the deposition plate 109. Since the sliding contact surface on the plate-like energizing member 108 is shielded when viewed from 160, film deposition on the contact surface can be significantly suppressed. Even when the film deposited on the contact surface scatters, the film does not enter the plasma space 160 side because it is blocked by the deposition preventing plate 109 and falls. Note that the deposition preventing plate 109 does not necessarily have to be at right angles to the plate-like energizing member 108, and only needs to face the plasma space 160.

In addition, since sliding surfaces are provided on both surfaces of one plate-like energizing member 108, the following effects can be obtained.
Even when the plate-like energizing member 108 is slightly inclined with respect to the moving direction of the stage 121 or when the contact finger 145 is inclined, at least one of the two opposing surfaces on the plate-like energizing member 108 is electrically contacted. Is formed and the conductive state is maintained. As a result, the grounding path is stably maintained even in a large-sized plasma apparatus having a limited device tolerance.

  Therefore, by using the plasma CVD apparatus having the above-described configuration, it is possible to carry in and out the substrate with the stage moving, and to form a large-area thin film uniformly, at high speed and stably.

  As a modification of the present embodiment, the same effect can be obtained by fixing the contact finger 145 on the vacuum chamber 101 side and fixing the plate-like energization member 108 on the outer peripheral portion of the stage 121.

Embodiment 4 FIG.
FIG. 8 is a cross-sectional view schematically showing the configuration of the grounding mechanism of stage 121 in the plasma apparatus according to the fourth embodiment. Compared with the contact finger 144 used in the third embodiment, the contact finger 146 that is a current-carrying member in the present embodiment has a substantially semicircular arc-shaped sliding portion that is not on the vacuum chamber 101 side, but on the adhesion prevention plate 152. It is different in that it points to the side.
The plate-shaped deposition preventing plate 152 fixed to the upper flange 103 supporting the shower plate 122 is made of a conductive material, and the upper flange is routed through the contact finger 146 and the deposition preventing plate 152 as a ground path from the stage 121. A route to 103 is formed. That is, the deposition preventing plate 152 is fixed to the upper flange 103 on the shower plate 122 side and also serves as a current-carrying member. As a form, the energization member is fixed relative to the shower plate 122, and the electric contact slides by the movement of the stage 121. Therefore, since the plate-shaped deposition preventing plate 152 has both a function as a shielding member that shields electrical contacts from plasma and a function as a current-carrying member, it can be considered that both are integrated.
The grounding path in this case is shortened compared to the case of passing through the lower flange 102, and the grounding impedance can be further reduced.
To prevent the generated particles from falling on the contact finger 146, a slit can be provided in a portion extending in parallel to the stage surface from the stage 121 so that the particles can easily fall.

  In addition, in the above configuration, it is not necessary to consider the parallel relationship between the moving direction of the stage 121 and the inner wall surface of the vacuum chamber 101. Instead, it is necessary to accurately determine the position of the upper flange 103, but sufficient accuracy can be obtained by general mechanical means such as setting a positioning pin on the lower flange 102. Therefore, the dimensional tolerance allowed in the large vacuum chamber 101 necessary for processing a particularly large deposition target substrate 170 is increased, and the manufacturing cost of the apparatus is suppressed.

  By using the plasma CVD apparatus having the above configuration, the substrate can be carried in and out after the stage is moved, and the ground impedance is small. Therefore, stable high frequency discharge can be obtained in the frequency region of the VHF band, and the large area can be obtained. It is possible to form a thin film uniformly, at high speed and stably.

  Note that the plasma apparatus of the present invention can also be applied to a plasma etching apparatus, an ashing apparatus, a sputtering apparatus, an ion implantation apparatus, and the like.

  In addition, when the plasma apparatus of the present invention is applied to a vertical apparatus, the shape and dimensions of the deposition plate and the contact finger above the plasma space 160 are appropriately adjusted so that particles do not fall into the plasma space 160. do it. Which type is selected can be selected as appropriate according to the use of the plasma apparatus. The present invention can be variously modified, modified, combined, etc. other than those described above.

101 Vacuum chamber 102 Lower flange 103 Upper flange 104 Gate valve 105 Deposition gas supply port 106 Exhaust port 107, 108 Plate-shaped energizing member 109 Depositing plate 111 High-frequency power source 112 Matching device 113 Feed bar 121 Stage 122 Shower plate 123 Electrode block 131 132, 133 Insulating spacer 141, 144, 145, 146 Contact finger 142 Screw member 143 Holding member 151, 152 Attachment plate 154 Insulating cover 160 Plasma space 170 Deposition substrate 180 Shield box 201 Curved surface

Claims (8)

A conductive vacuum chamber;
A shower plate having a gas supply port installed insulated from the vacuum chamber;
A stage on which a substrate placed facing the shower plate is mounted;
Power supply means for supplying high frequency power to the shower plate;
Grounding means for grounding the vacuum chamber;
A stage moving mechanism that moves the stage to adjust the distance between the stage and the shower plate;
A conductive current-carrying member that is fixed to the outer periphery of the stage and short-circuits between the outer periphery and the vacuum chamber;
The energizing member forms an electrical contact that slides along the movement of the stage,
The plasma device is characterized in that the electrical contact is shielded from the plasma of the gas generated between the shower plate and the substrate by the high frequency power. 2. The plasma device according to claim 1, wherein the energizing member is in contact with a second energizing member made of a material different from the vacuum chamber fixed to an inner wall portion of the vacuum chamber to form the electrical contact. . The plasma apparatus according to claim 1, wherein the energization member is fixed to a mounting surface side of the substrate on the stage. 2. The plasma apparatus according to claim 1, wherein the electrical contact is formed at a position away from the mounting surface of the substrate of the stage in the shower plate side direction. The electrical contacts are formed on two planes facing each other on the surface of the plate-like energizing member or the plate-like second energizing member, which are parallel to the moving direction of the stage. The plasma apparatus according to claim 2. The electrical contact is shielded from the plasma by a plate-shaped shielding member,
The plasma apparatus according to claim 2, wherein the plate-shaped shielding member is integral with the energization member or the second energization member. The vacuum chamber can be opened and closed with a flange parallel to the mounting surface of the substrate of the stage,
The plasma apparatus according to claim 2, wherein the second energization member is fixed to the vacuum chamber on the grounding means side. After the stage on which the substrate is mounted moves in the direction approaching the shower plate to form the electrical contact, film formation is performed by chemical vapor deposition,
8. The plasma apparatus according to claim 1, wherein the stage is moved in a direction away from the shower plate after film formation is completed, and the substrate is transferred from the stage. 9. A method for manufacturing a semiconductor thin film.

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