JP2011003744A - Surface treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for performing surface treatment to a surface of a workpiece having a groove or hole of a high aspect ratio.SOLUTION: The surface treatment device includes: a treatment chamber 3 for making a reactant gas chemically react with a surface of a workpiece 1; a reactant gas-supplying part 6 for supplying the reactant gas to the treatment chamber through an introduction passage of the reactant gas; and a pressure variation part 8 for varying the pressure of the treatment chamber by supplying an introduction gas to the treatment chamber separately from the introduction passage of the reactant gas. The surface treatment device is structured such that the introduction gas is supplied to the treatment chamber from the pressure variation part 8 through an introduction gas-supplying part 7 by periodically varying the pressure of the introduction gas to high pressure and low pressure in the range of 6,666-101,325 Pa, and thereby the pressure in the treatment chamber is varied to run the reactant gas into/from the hole or groove 2.

Description

  The present invention relates to an apparatus for surface-treating a workpiece surface having a high aspect ratio groove or hole.

  In recent years, a product called MEMS (Micro Electro Mechanical Systems) in which a structure having a groove or a hole having a high aspect ratio with an opening of 1 mm or less is formed by a chemical reaction has been put into practical use. As miniaturization of semiconductor elements progresses, element structures in which holes having a high aspect ratio are formed and a conductive material is embedded have been put into practical use. As a common processing technique for realizing such a structure, processing of high aspect ratio holes and grooves and film formation are required.

FIG. 1 is an explanatory diagram for explaining a velocity boundary layer in the vicinity of a workpiece surface and a hole or groove having a high aspect ratio (aspect ratio, length 1 / width / diameter d). Generally, when surface treatment is performed by gas phase reaction under continuous flow, the velocity boundary layer is near the workpiece surface (the velocity boundary layer has a velocity change from the object wall surface to the main flow regardless of laminar flow / turbulent flow. A region layer h) is formed, and the gas flow velocity becomes zero on the workpiece surface. Gas flow does not occur in grooves and holes smaller than the velocity boundary layer size (no static pressure difference), and the reaction raw material reaches the workpiece surface in the grooves and holes only by diffusion due to the concentration difference (A in FIG. 1). To do.
Since the transport of reaction raw materials by diffusion is much smaller than that by gas flow, the amount of raw materials that reach the inside of holes and grooves with a high aspect ratio is reduced, requiring a long time for surface treatment. become.

  In addition, when reactive material particles such as PVD and plasma etching are physically impacted against the workpiece surface for surface treatment, the flying angle at which the reactive material particles can reach the inside of the grooves and holes with a high aspect ratio is narrowed, and the amount of material reached Therefore, the surface treatment takes a long time.

  Conventionally, the method of Patent Document 1 is known as a film forming technique for a substrate provided with a hole having a high aspect ratio. A method of forming a film at a high coverage in a hole having a high aspect ratio by performing a process of depositing a material that is a core of film formation and a film formation reaction process separately is shown. This method is a method for improving the surface reaction in a hole with a high aspect ratio, and does not improve that the reaction gas is difficult to reach. Vapor phase surface treatment is not possible.

  As seen in the method of Patent Document 2, when processing the object to be processed in the vacuum chamber via the plasma generated by ionizing the reaction gas in the vacuum chamber, the processing process of the object to be processed is in progress. In addition, the pressure of the reaction gas in the vacuum chamber is periodically changed between a high pressure value exceeding 0.1 Pa and a low pressure value at which plasma cannot be maintained, so that the abundance ratio of active species in the plasma is increased. An object processing method characterized by controlling is known.

  In this conventional technique, the presence of active species at a low pressure value in which the plasma cannot be maintained under a constant pressure condition by periodically changing the pressure of the reaction gas in the vacuum chamber between the high pressure value and the low pressure value. An average existence ratio close to the ratio is stably realized. The purpose of the pressure fluctuation of this technology is to control the abundance ratio of active species in the plasma in the vacuum chamber based on new knowledge. In addition, since the number of collisions between active species increases and the degree of activity is deactivated as the pressure is higher, this conventional technique attempts to configure the process at the lowest possible pressure. At that time, the aim is to set up the process at a pressure below the plasma generation pressure limit that becomes a bottleneck.

In this prior art, it is considered that the target is not the gas flow (continuous flow), but the free movement of the active species (radicals and ions) and the phenomenon of collision, and the device is not intended for the inflow and outflow of the gas flow. . The high pressure side is over 0.1 Pa (at most 10 Pa), and the mean free path of the molecule (the average value of the distance that can travel without being disturbed by scattering) is 1 to 100 mm. In general, since the thickness of a silicon wafer is 0.5 to 1 mm, the hole size of a fine hole having a high aspect ratio (5 or more) is about 200 μm (representative length) at the maximum.
Therefore, in this prior art, the Knudsen number (average free process / representative length) is about 5 to 500, so the area around the microhole is not a continuous flow but a free molecular flow (highly diluted state). (Knusen number <0.1 is necessary for continuous flow).

In the situation of free molecular flow, there is little effect on the mass transport of the flow, and the active species move in and out of the microhole by free motion (thermal motion), so even if the pressure fluctuates, It can be said that there is almost no transport phenomenon.
Therefore, even in this conventional technology, since the transport of the reaction raw material by diffusion is very small compared to the case of using a gas flow, the amount of the raw material that reaches the inside of the holes and grooves having a high aspect ratio is reduced, and the surface treatment takes a long time. Will be needed.

  Patent Document 3 merely discloses a technique for controlling the pressure of the processing chamber so as to become a predetermined constant pressure by using a pressure adjusting gas, without controlling the exhaust amount of the substrate processing chamber. The pressure of the reaction gas is not periodically changed between the high pressure value and the low pressure value.

JP 2002-146531 A Japanese Patent No. 3646292 JP 2006-120822 A

  In view of the above problems, the present invention provides an apparatus for surface-treating a workpiece surface having a high aspect ratio groove or hole.

  In order to solve the above problems, the invention of claim 1 provides conductivity to an insulator or silicon in a hole or groove (2) having a high aspect ratio of 2 or more formed on the surface of the workpiece (1). A surface treatment device that chemically reacts a reaction gas to embed a material doped with a minute amount of impurities for performing a chemical reaction on the surface of the workpiece (1). In addition to the processing chamber (3) to be supplied, the reaction gas supply unit (6) for supplying the reaction gas to the processing chamber through the reaction gas introduction path, and the reaction gas introduction path, the introduction gas to the treatment chamber In the surface treatment apparatus having a pressure fluctuation section (8) that varies the pressure of the processing chamber by supplying the pressure, the pressure of the introduced gas is periodically fluctuated between high pressure and low pressure within a range of 6666 Pa to 101325 Pa. Then, by supplying the introduced gas from the pressure fluctuation section (8) to the processing chamber via the introduction gas supply section (7), the pressure in the processing chamber is varied to allow the reaction gas to flow into the hole. Or it is a surface treatment apparatus made to flow in and out of a groove | channel (2).

  As a result, by periodically changing the pressure in the processing chamber, the reactive gas is forcibly introduced and discharged into the minute grooves and holes on the workpiece surface, so that the entire workpiece surface can be surface-treated at high speed and with high uniformity. . Since it is a surface treatment under the occurrence of gas flow (continuous flow), by changing the pressure of the processing chamber by supplying the introduction gas to the processing chamber, even inside the holes and grooves with a high aspect ratio, The raw material can be positively reached.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the pressure of the introduced gas is varied in a cycle of 0.1 to 100 Hz.

According to a third aspect of the invention, in the first aspect of the invention, the processing chamber (3) includes an upper surface portion (3 ′), a side surface portion (3 ″), and a lower surface portion (3 ′ ″). The part (3 ′) is provided with the reaction gas supply part (6) and the introduction gas supply part (7) installed so as to surround the reaction gas supply part (6). 3 ′ ″) is provided with a support base (4) on which the workpiece (1) is arranged.
Thereby, it is possible to prevent the introduced gas for pressure fluctuation from reaching the workpiece surface to be surface-treated.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the introduction gas supply unit (7) is further provided in the side surface portion (3 ''), and the introduction gas supply unit (7) A plurality of introduction holes provided in the side surface (3 ″) are provided, and the introduced gas is supplied to the processing chamber from the entire side surface (3 ″).
Thereby, it is possible to further suppress the release of impurities inappropriate for the surface treatment of the workpiece from the side surface of the processing chamber.

  The invention according to claim 5 is the invention according to claim 3 or 4, wherein the pressure fluctuation section (8) periodically controls the gas supply source (20) of the introduced gas and the supply or stop of the introduced gas. And a valve (21). Thereby, the entire work surface can be surface-treated at high speed and with high uniformity by forcibly introducing and discharging the reaction gas into the minute grooves or holes on the work surface.

  According to a sixth aspect of the present invention, in the third or fourth aspect of the present invention, the pressure fluctuation section (8) slides in the cylinder (22) connected to the introduced gas supply section (7) and the cylinder (22). It comprises a moving piston (23) and an actuator for periodically extending and contracting the piston (23).

  According to a seventh aspect of the present invention, in the third or fourth aspect of the invention, the pressure fluctuation section (8) is connected to the introduction gas supply section (7), and the variable capacity section (24) ) Is periodically expanded and contracted.

  In addition, the code | symbol attached | subjected above is an example which shows a corresponding relationship with the specific embodiment as described in embodiment mentioned later.

It is explanatory drawing explaining the speed boundary layer near the workpiece | work surface, and the hole or groove | channel of a high aspect ratio. It is explanatory drawing explaining the state by which the material 2 'which doped the micro amount impurity for providing electroconductivity to an insulator or silicon | silicone was embedded in the groove | channel or hole 2 formed in the surface of the workpiece | work 1. FIG. It is explanatory drawing which carries in and carries out the workpiece | work 1 in the surface treatment apparatus which is one Embodiment of this invention. It is the schematic which shows the surface treatment apparatus which is one Embodiment of this invention. It is the schematic which shows the pressure fluctuation apparatus 8 in one Embodiment of this invention. It is the schematic which shows the introduction gas supply part 7 in other one Embodiment of this invention. It is the schematic which shows the pressure fluctuation apparatus 8 in other one Embodiment of this invention. It is the schematic which shows the pressure fluctuation apparatus 8 in other one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. About each embodiment, the same code | symbol is attached | subjected to the part of the same structure, and the description is abbreviate | omitted.
FIG. 2 is a diagram for explaining a state in which a groove 2 or a hole 2 formed on the surface of the workpiece 1 is filled with a material 2 ′ doped with a minute amount of impurities for imparting conductivity to an insulator or silicon. FIG. FIG. 3 is an explanatory diagram for loading and unloading the workpiece 1 into and from the surface treatment apparatus according to the embodiment of the present invention. FIG. 4 is a schematic view showing a surface treatment apparatus according to an embodiment of the present invention. FIG. 5 is a schematic view showing the pressure fluctuation device 8 in one embodiment of the present invention.
Examples of the work 1 include a silicon wafer, a substrate, and a semiconductor device. Examples of the surface treatment include CVD and plasma CVD.

  In a deep groove or hole 2 formed on the silicon wafer 1 and having a width of 1 to 200 μm and an aspect ratio of 2 or more, a material 2 ′ doped with a minute amount of impurities for imparting conductivity to silicon is formed by a thermal CVD method, One embodiment of forming and embedding by plasma CVD or the like will be described below. As shown in FIG. 2, the case where the material 2 ′ is embedded will be described. However, it is apparent that the present invention can be similarly applied even when the film is formed in the groove or the hole. In general, the silicon high aspect ratio processing typically has an opening of several to several tens of μm and a depth of 100 μm or less.

As shown in FIGS. 3 and 4, the surface treatment apparatus of this embodiment includes a treatment chamber 3 composed of an upper surface portion 3 ′, a side surface portion 3 ″, and a lower surface portion 3 ′ ″, and a support base on which a workpiece is placed. 4, heating device 5, reaction gas supply unit 6 connected by a plurality of holes in the upper surface part 3 ′, pressure fluctuation device 8, and an introduction gas supply unit for introducing the introduced gas for pressure fluctuation from the pressure fluctuation device 8 into the processing chamber 3. 7, an exhaust port 9, an exhaust pump 15, a holding chamber 11 for cooling the surface-treated device, an exhaust gas exclusion device 12, a transport table 13, and a transport device 14.
As shown in FIG. 3, the silicon wafer 1 as a work is carried into and out of the processing chamber 3. After the silicon wafer 1 is placed on the transfer table 13 by another transfer device, it is carried into the processing chamber 3 through the door 10 having an opening / closing mechanism by the transfer device 14, and is placed on the support table 4 that holds the silicon wafer 1. Placed.

When the silicon wafer 1 to be surface-treated is placed on the table 13, it is carried into the processing chamber by the transfer device 14. After the transfer, the processing chamber door 2 is closed, and the processing chamber is replaced with H ₂ gas. Next, an apparatus for surface treatment with the work heating device 5 is heated to a treatment temperature (about 1000 ° C. as an example). After the heating, the reaction gas is supplied from the reaction gas supply unit 6. As an example of the reaction gas, SiH ₄ , SiH ₂ Cl ₂ , SiHCl ₃ is used as a main film forming material, B ₂ H ₆ , PH ₃ , AsH _3, etc. are mixed in an appropriate amount and diluted with H _2. Use.

The pressure fluctuation device 8 shown in FIG. 5 includes a gas supply source 20 and a valve 21, and the valve 21 is installed between the gas supply source 20 and the processing chamber 3. The gas supply source 20 supplies a higher pressure than the processing chamber 3. As an example, a pressure gas (H ₂ , N ₂ , Ar, etc.) twice or more in the processing chamber is supplied to the processing chamber 3. While performing the surface treatment, the valve 21 opens and closes at about 0.01 to 1000 Hz, thereby generating a pressure fluctuation of about 0.01 to 1000 Hz in the processing chamber.

The reaction gas is supplied to the processing chamber 3 by the reaction gas supply unit 6 through the reaction gas introduction path. Separately from the reaction gas introduction path, the introduction gas is supplied to the processing chamber 3 by the introduction gas supply unit 7. As shown in FIG. 4, the introduction gas supply unit 7 is installed on the upper surface portion 3 ′ of the processing chamber 3 so as to surround the reaction gas supply unit 6. A support table 4 on which the silicon wafer 1 as a work is disposed is provided on the lower surface 3 ′ ″ of the processing chamber 3. An introduction gas supply unit 7 installed in the processing chamber is installed at a position other than the workpiece position in the upper surface portion 3 ′ of the processing chamber 3 so that the introduced gas for pressure fluctuation does not reach the workpiece surface to be surface-treated. In the present embodiment, the exhaust port 9 is provided on the outer periphery of the support base 4, which is the lower surface portion 3 ′ ″ of the processing chamber 3 corresponding to the ejection of the introduction gas supply unit 7.
By adopting a processing chamber structure in which gas is introduced in a direction along the processing chamber wall surface and reaches the exhaust port, the workpiece can be surface-treated without reaching the supply gas for pressure fluctuation. By such a mechanism that the introduction gas supply unit 7 for pressure adjustment is installed outside the work position and supplies an inert gas, it has a function of protecting the apparatus wall surface simultaneously with the application of pressure fluctuation. . The introduced gas is supplied along the entire wall surface.

  When the silicon wafer 1 that is a workpiece is subjected to a surface treatment reaction in the processing chamber, the reaction gas is forcibly introduced and discharged into minute grooves or holes on the surface of the workpiece by periodically changing the pressure in the processing chamber. As a result, the entire workpiece surface can be surface-treated at high speed and with high uniformity. In the process of changing the pressure, the source gas flows into and out of the hole or groove on the workpiece, and the raw material is supplied to the groove or hole. When the frequency is 1000 Hz or higher, the equipment structure that generates pressure fluctuation becomes difficult. When the frequency is 0.01 Hz or lower, the frequency of pressure fluctuation that causes a gas flow is small, and the raw material supply action by the gas flow becomes small against diffusion. It is preferable that the pressure of the introduced gas is changed at a period of 0.1 to 100 Hz and a pressure fluctuation of about 0.1 to 100 Hz is generated in the processing chamber.

  When the pressure fluctuates, the gas is discharged from the grooves and holes when the processing chamber is at a low pressure, and the raw material gas flows into the holes and grooves when the pressure is high. Therefore, when the pressure fluctuation width (amplitude) and the fluctuation cycle are the same, in order to allow more raw materials to flow into the holes and grooves in one cycle, it is preferable to shorten the low pressure time and lengthen the high pressure time. For this reason, the installation which has the exhaust capability which can make low pressure time 1 second or less is preferable. If the pressure is changed, the inflow and outflow of the raw material gas into the deep hole and the groove can be increased as compared with the case where the pressure is not changed. A curve formed by a rectangular wave, a sine wave, a triangular wave, a sawtooth wave, or a combination thereof can be used.

When a predetermined reaction is obtained, the supply of the raw material gas and the heating of the surface-treated silicon wafer 1 (workpiece) are stopped, and the inert gas (Ar, N ₂ ) is supplied and cooled until the transportable temperature is reached. When the transferable temperature is reached, the door 2 of the processing chamber is opened, and the transfer device 14 transfers the processing chamber 3 to the holding chamber (cooling chamber) 11. The work conveyed to the holding chamber (cooling chamber) 11 is taken out and cooled until the temperature is reached. When the workpiece temperature reaches the removal temperature, the workpiece is removed from the holding chamber 11.

The surface treatment apparatus of the present embodiment is intended for products having a high pressure of 50 to 760 Torr (6666 to 101325 Pa) and a hole / groove width of 1 mm or less, and preferably a microhole / groove width of 1 to 200 μm, and the Knudsen number <0. The process is built in the area of .1.
For this reason, when a hole or groove 2 having a high aspect ratio of 2 or more formed on the surface of the work 1 is embedded with an insulator or a material doped with a minute amount of impurities for imparting conductivity to silicon, A continuous flow as described in lean gas dynamics (see Mechanical Engineering Handbook Basic α4 etc.) is generated.

On the other hand, in the situation of the free molecular flow of Patent Document 2, the transport of the reaction raw material by diffusion is very small as compared with the case of the gas flow. For this reason, there is little influence on the mass transport of the flow, and it can be said that there is almost no transport phenomenon of the material due to the flow even if the pressure fluctuates because it moves in and out of the fine hole by free motion (thermal motion). It is.
On the other hand, since the surface treatment apparatus of the present embodiment is a surface treatment under the generation of a gas flow (continuous flow), by supplying the introduction gas to the treatment chamber 3, the pressure in the treatment chamber is changed. Moreover, the raw material can be made to reach the inside of the hole and groove having a high aspect ratio positively. For this reason, the reactive gas can be chemically reacted and embedded without taking a long time for the surface treatment.

  Next, another embodiment of the present invention will be described for the pressure fluctuation device 8 and the introduced gas supply unit 7. FIG. 6 is a schematic view showing an introduction gas supply unit 7 in another embodiment of the present invention. FIG. 7 is a schematic diagram showing a pressure fluctuation device 8 according to another embodiment of the present invention. FIG. 8 is a schematic diagram showing a pressure fluctuation device 8 according to another embodiment of the present invention.

  In another embodiment of the present invention shown in FIG. 6, one or more introduction gas supply units 7 are provided on the side surface 3 ″ of the processing chamber 3. In this case, the introduction gas supply unit 7 may not be installed on the upper surface portion 3 ′ of the processing chamber 3, but it is more preferable that the introduction gas supply unit 7 is also installed on the upper surface portion 3 ′ of the processing chamber 3. If the introduction gas is supplied simultaneously from the upper surface portion 3 ′ and the entire side surface 3 ″ of the processing chamber 3, it is possible to further suppress the release of impurities inappropriate for the surface treatment of the workpiece from the side surface of the processing chamber. .

  In order to supply the introduction gas from the entire side surface 3 ″ of the processing chamber 3, a plurality of introduction holes may be installed in the side surface 3 ″ of the processing chamber as a whole. In order to supply the introduction gas from the introduction gas supply unit 7 to the introduction hole, it may be connected by a conduit, or may be supplied by providing a space so as to surround the side surface portion 3 '' of the processing chamber from the outer periphery. . When the introduced gas is supplied from the side surface portion 3 ″ of the processing chamber 3, the pressure of the introduced gas supplied from the side surface portion 3 ″ of the processing chamber 3 is set to the pressure of the introduced gas supplied from the upper surface portion 3 ′ of the processing chamber 3. Compared to the above, it is preferable to adjust appropriately so that the introduced gas does not reach the surface of the workpiece to be surface-treated.

  As another embodiment of the pressure fluctuation device 8, as shown in FIG. 7, the pressure fluctuation unit 8 includes a cylinder 22 connected to the introduction gas supply unit 7 through an introduction hole, and a piston 23 that slides in the cylinder 22. And an actuator (not shown) that periodically drives the piston 23 to extend and contract. Further, as shown in FIG. 8, the pressure fluctuation unit 8 includes a variable capacity unit 24 connected to the introduction gas supply unit 7 and an actuator (not shown) that periodically drives the variable capacity unit 24 to extend and contract. It may be. The variable capacity part 24 may be constituted by a bellows-like capacity part shown in FIG. 8 or other elastic body. In the two other embodiments described above, in order to supply the introduction gas from the introduction gas supply unit 7 to the introduction hole, it may be connected by a conduit, but the side surface portion 3 '' of the processing chamber is surrounded by the entire outer periphery. It is also possible to provide the space provided in the above manner.

  Therefore, the closed space in which the piston reciprocates is connected to the surface treatment chamber, and the piston is provided with a device that reciprocates from the opposite side of the treatment chamber. As a result, a pressure cycle is generated in the processing chamber. In addition, since the closed space for generating pressure fluctuation that changes in volume is connected to the surface treatment chamber, and the closed space for generating pressure fluctuation includes a device that periodically changes the volume from the outside, A high-pressure gas is periodically introduced into the processing chamber, and a pressure cycle is generated in the processing chamber.

DESCRIPTION OF SYMBOLS 1 Work, silicon wafer 2 Hole or groove 3 Processing chamber 4 Support stand 5 Heating device 6 Reaction gas supply part 7 Introduced gas supply part 8 Pressure fluctuation part 9 Exhaust port 10 Door 20 Gas supply source 21 Valve 22 Cylinder 23 Piston 24 Variable capacity Part

Claims (7)

In order to embed an insulator or a material doped with a minute amount of impurities for imparting conductivity to silicon in a hole or groove (2) having a high aspect ratio of 2 or more formed on the surface of the work (1) And a surface treatment apparatus for chemically reacting the reaction gas,
The surface treatment apparatus has a treatment chamber (3) that chemically reacts the reaction gas with the surface of the workpiece (1), and a reaction gas supply unit that supplies the reaction gas to the treatment chamber through the reaction gas introduction path ( 6) and a surface treatment apparatus comprising a pressure fluctuation section (8) for varying the pressure of the processing chamber by supplying the introduction gas to the processing chamber separately from the reaction gas introduction path,
The pressure of the introduced gas is periodically fluctuated between high pressure and low pressure within a range of 6666 Pa to 101325 Pa, and the treatment of the introduced gas from the pressure fluctuation section (8) through the introduction gas supply section (7). A surface treatment apparatus in which the reaction gas is caused to flow into and out of the hole or groove (2) by changing the pressure in the treatment chamber by supplying to the chamber.   The surface treatment apparatus according to claim 1, wherein the pressure of the introduced gas is changed in a cycle of 0.1 to 100 Hz.   The processing chamber (3) includes an upper surface portion (3 ′), a side surface portion (3 ″), and a lower surface portion (3 ′ ″). The upper surface portion (3 ′) includes the reaction gas supply unit ( 6) and the introduction gas supply part (7) installed so as to surround the reaction gas supply part (6), and the work (1) is provided on the lower surface part (3 ′ ″). The surface treatment apparatus according to claim 1, wherein a support base (4) to be arranged is provided.   Further, the side gas (3 ″) is also provided with the introduction gas supply unit (7), and the introduction gas supply unit (7) is provided in the plurality of side surfaces (3 ″). The surface treatment apparatus according to claim 3, further comprising an introduction hole, wherein the introduction gas is supplied to the treatment chamber from the entire side surface portion (3 ″).   The said pressure fluctuation | variation part (8) is equipped with the gas supply source (20) of the said introduction gas, and the valve | bulb (21) which controls the supply or stop of the said introduction gas periodically. Or the surface treatment apparatus of 4.   The pressure fluctuation section (8) is configured to periodically connect a cylinder (22) connected to the introduction gas supply section (7), a piston (23) sliding in the cylinder (22), and the piston (23). The surface treatment apparatus according to claim 3, further comprising an actuator that is driven to extend and contract.   The pressure fluctuation section (8) includes a variable capacity section (24) connected to the introduction gas supply section (7) and an actuator that periodically expands and contracts the variable capacity section (24). The surface treatment apparatus according to claim 3 or 4.

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