JP6358020B2 - Deposition equipment - Google Patents

Description

  The present invention relates to a film forming apparatus for forming a film on the surface of a work material having conductivity such as steel using plasma.

  Conventionally, a technique for forming a film on the surface of a work material having conductivity, such as a steel material, is known from Patent Document 1 or the like. In the technique disclosed in this patent document, a plasma generating device supplies a microwave toward a material to be processed in a processing container disposed so as to protrude from the quartz window through the quartz window. The plasma is generated in this way, and a sheath layer is generated at the boundary between the plasma and the material to be processed. During the supply of the microwave, the plasma generator applies a negative bias voltage to the workpiece material. As a result, a sheath layer is generated along the surface of the workpiece material, and the generated sheath layer is expanded. The supplied microwave propagates along the sheath layer, and the plasma expands. As a result, the source gas is decomposed by the plasma, and the surface of the material to be processed is subjected to film formation.

JP 2004-47207 A

  In the technology disclosed in Patent Document 1, when the thickness of the sheath layer changes in the microwave propagating as a surface wave through the interface between the sheath layer and the plasma formed along the processing surface of the material to be processed, the surface wave Since the impedance with respect to changes, a part of the surface wave is reflected. Also, the thinner the sheath layer, the greater the resistance loss that occurs on the treated surface of the material being processed. As a result, the plasma density decreases as the distance from the quartz window increases. As a result, the processing capability of film formation on the processing material on the side opposite to the quartz window is lower than the processing capability of film formation on the processing material on the quartz window side.

  The present invention has been made in order to solve the above-described problems. Compared to the processing capability of film formation on the workpiece material on the microwave supply port side, the present invention is directed to the workpiece material on the side opposite to the microwave supply port. An object of the present invention is to provide a film forming apparatus capable of reducing a decrease in the processing capability of the film forming.

  In order to achieve the above object, a film forming apparatus according to claim 1 includes a microwave supply unit that supplies a microwave for generating plasma along a processing surface of a conductive material to be processed, A negative voltage applying unit that applies a negative bias voltage to the workpiece material to expand the sheath layer along the processing surface of the processing material, and a microwave supplied from the microwave supply unit is propagated to the expanded sheath layer A negative supply voltage application terminal member that applies a negative bias voltage applied by the negative voltage application unit to the workpiece material that protrudes from the microwave supply port. An electrode for enlarging the thickness of the sheath layer formed on the side opposite to the microwave supply port, and a positive voltage connected to GND or supplied from a positive voltage application unit is applied. It is, and characterized in that it comprises an auxiliary electrode disposed around the outside of the protruding and placed the material to be processed.

  According to the film forming apparatus of the first aspect, the electric field strength around the outside of the material to be processed on the auxiliary electrode side is increased. As a result, the sheath layer generated around the outside of the material to be processed on the auxiliary electrode side becomes thicker than the sheath layer generated when the auxiliary electrode is not provided. Therefore, it is possible to provide a film forming apparatus in which the attenuation of the density of plasma generated around the outside of the material to be processed on the auxiliary electrode side is reduced and the reduction in film forming processing capability is reduced.

  The auxiliary electrode may be provided at a position sandwiching the workpiece material with respect to the microwave supply port. In this case, since the auxiliary electrode is provided at a position sandwiching the material to be processed, the electric field intensity around the outside of the material to be processed farthest from the microwave supply port becomes stronger. As a result, the sheath layer generated around the outside of the work material farthest from the microwave supply port becomes thicker. Accordingly, it is possible to provide a film forming apparatus in which the attenuation of the density of the plasma generated around the outside of the work material farthest from the microwave supply port is further reduced, and the decrease in film forming processing capability is further reduced. it can.

The auxiliary electrode may extend in a direction perpendicular to the protruding direction of the workpiece material . In this case, the electric field strength around the outside of the work material farthest from the microwave supply port becomes stronger. This makes it easier for the electric field to concentrate in a region surrounded by the auxiliary electrode extending in the thickness direction of the sheath layer and the material to be processed. As a result, the sheath layer generated around the outside of the work material farthest from the microwave supply port becomes thicker. Accordingly, it is possible to provide a film forming apparatus in which the attenuation of the density of the plasma generated around the outside of the work material farthest from the microwave supply port is further reduced, and the decrease in film forming processing capability is further reduced. it can.

In addition, a larger positive voltage value may be applied to the auxiliary electrode as the distance from the workpiece material becomes longer . In this case, the electric field strength around the outside of the work material farthest from the microwave supply port becomes stronger. As a result, the sheath layer generated around the outside of the work material farthest from the microwave supply port becomes thicker. Accordingly, it is possible to provide a film forming apparatus in which the attenuation of the density of the plasma generated around the outside of the work material farthest from the microwave supply port is further reduced, and the decrease in film forming processing capability is further reduced. it can.
Furthermore, the electric field strength is increased not only at the electric field intensity around the outside of the work material farthest from the microwave supply port, but also at a position on the way from the farthest position to the microwave supply port. Therefore, a film deposition apparatus that reduces the attenuation of the density of plasma generated around the outside of the material to be processed at a position on the way from the farthest position to the microwave supply port, and further reduces the decrease in film forming processing capability. Can be provided.

Further, the auxiliary electrode may be curved toward the microwave supply port as the distance from the workpiece material becomes longer . In this case, the electric field strength around the outside of the work material farthest from the microwave supply port becomes stronger. Since the end portion of the curved auxiliary electrode approaches the material to be processed, the electric field strength in the region surrounded by the auxiliary electrode and the material to be processed becomes larger. As a result, the sheath layer generated around the outside of the work material farthest from the microwave supply port becomes thicker. Accordingly, it is possible to provide a film forming apparatus in which the attenuation of the density of the plasma generated around the outside of the work material farthest from the microwave supply port is further reduced, and the decrease in film forming processing capability is further reduced. it can.

  Furthermore, the electric field strength is increased not only at the electric field intensity around the outside of the work material farthest from the microwave supply port, but also at a position on the way from the farthest position to the microwave supply port. Therefore, a film deposition apparatus that reduces the attenuation of the density of plasma generated around the outside of the material to be processed at a position on the way from the farthest position to the microwave supply port, and further reduces the decrease in film forming processing capability. Can be provided.

  The auxiliary electrode may be disposed along a protruding direction of the workpiece material with respect to the microwave supply port. In this case, the electric field strength around the outside of the work material farthest from the microwave supply port becomes stronger. As a result, the sheath layer generated around the outside of the work material farthest from the microwave supply port becomes thicker. Accordingly, it is possible to provide a film forming apparatus in which the attenuation of the density of the plasma generated around the outside of the work material farthest from the microwave supply port is further reduced, and the decrease in film forming processing capability is further reduced. it can.

  The auxiliary electrode may be arranged such that the distance from the workpiece material is shorter on the opposite side than on the microwave supply port side. In this case, the electric field strength around the outside of the work material farthest from the microwave supply port becomes stronger. As a result, the sheath layer generated around the outside of the work material farthest from the microwave supply port becomes thicker. Accordingly, it is possible to provide a film forming apparatus in which the attenuation of the density of the plasma generated around the outside of the work material farthest from the microwave supply port is further reduced, and the decrease in film forming processing capability is further reduced. it can.

  The auxiliary electrode may be applied with a positive voltage having a larger value on the opposite side than on the microwave supply port side. In this case, the electric field strength around the outside of the work material farthest from the microwave supply port becomes stronger. As a result, the sheath layer generated around the outside of the work material farthest from the microwave supply port becomes thicker. Accordingly, it is possible to provide a film forming apparatus in which the attenuation of the density of the plasma generated around the outside of the work material farthest from the microwave supply port is further reduced, and the decrease in film forming processing capability is further reduced. it can.

  The positive voltage applied to the auxiliary electrode is applied to at least a part of a period in which a negative bias voltage is applied by the negative voltage application unit and a microwave is supplied by the microwave supply unit. Also good.

It is explanatory drawing which shows schematic structure of the film-forming apparatus of 1st Embodiment. It is explanatory drawing which shows the microwave pulse, negative voltage pulse, and positive voltage of 1st Embodiment. It is sectional drawing of the Z direction which shows arrangement | positioning of the microwave supply port of 1st Embodiment, a to-be-processed material, a negative voltage electrode, and an auxiliary electrode. It is a graph which shows distribution of the film thickness in the position of the to-be-processed material of a Z direction when a positive voltage is applied to an auxiliary electrode, when an auxiliary electrode is not provided, and when an auxiliary electrode is GND-connected. It is sectional drawing of the Z direction which shows arrangement | positioning of the microwave supply port of the modification 1, a to-be-processed material, a negative voltage electrode, and an auxiliary electrode. It is sectional drawing of the Z direction which shows arrangement | positioning of the microwave supply port of the modification 2, a to-be-processed material, a negative voltage electrode, and an auxiliary electrode. It is sectional drawing of the Z direction which shows arrangement | positioning of the microwave supply port of 2nd Embodiment, a to-be-processed material, a negative voltage electrode, and an auxiliary electrode. It is sectional drawing of the Z direction which shows arrangement | positioning of the microwave supply port of the modification 3, a to-be-processed material, a negative voltage electrode, and an auxiliary electrode. It is sectional drawing of the Z direction which shows arrangement | positioning of the microwave supply port of the modification 4, a to-be-processed material, a negative voltage electrode, and an auxiliary electrode.

<First Embodiment>
Hereinafter, a first embodiment of a film forming apparatus 1 of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the film forming apparatus 1 includes a processing container 2, a vacuum pump 3, a gas supply unit 5, a control unit 6, and the like. The processing container 2 is made of metal such as stainless steel and has a hermetic structure. The vacuum pump 3 is a pump capable of evacuating the inside of the processing container 2 via the pressure adjustment valve 7. Inside the processing container 1, a conductive work material 8 that is a film formation target is supported by a microwave supply port 22.

  The material of the work material 8 is not particularly limited as long as the treatment surface 10 has conductivity, but in this embodiment, it is low-temperature tempered steel. Here, the low-temperature tempered steel is a material such as JIS G4051 (carbon steel material for machine structure), G4401 (carbon tool steel material), G44-4 (steel material for alloy tool), or maraging steel material. In addition to the low-temperature tempered steel, the work material 8 may be ceramic or resin in which a conductive material is coated.

  The gas supply unit 5 supplies a film forming source gas and an inert gas into the processing container 2. Specifically, an inert gas such as He, Ne, Ar, Kr, or Xe and a source gas such as CH4, CH2, C2H2, or TMS (tetramethylsilane) are supplied. In the present embodiment, description will be made on the assumption that the workpiece material 8 is subjected to a DLC (Diamond Like Carbon) film formation process using CH4, C2H2, and TMS source gases.

  The flow rate and pressure of the source gas and the inert gas supplied from the gas supply unit 5 may be controlled via the control unit 6 or may be controlled by an operator. The source gas may be a gas containing a compound having a CH bond such as alkyne, alkene, alkane, aromatic compound, or a compound containing carbon. H2 may be included in the source gas.

  Plasma for performing the DLC film forming process on the material 8 to be processed held inside the processing container 2 is generated. This plasma is generated by the microwave pulse controller 11, the microwave oscillator 12, the microwave power source 13, the negative voltage power source 15, and the negative voltage pulse generator 16. In the present embodiment, description will be made on the assumption that surface wave excitation plasma is generated by a method disclosed in Japanese Patent Application Laid-Open No. 2004-47207 (hereinafter referred to as “MVP method (Microwave shear-Voltage combination Plasma method)”). In the following description, the MVP method will be described.

  The microwave pulse control unit 11 oscillates a pulse signal in accordance with an instruction from the control unit 6 and supplies the oscillated pulse signal to the microwave oscillator 12. The microwave oscillator 12 generates a microwave pulse according to the pulse signal from the microwave pulse controller 11. The microwave power source 13 supplies power to the microwave oscillator 12 that oscillates a microwave of 2.45 GHz with the instructed output in accordance with an instruction of the control unit 6. That is, the microwave oscillator 12 supplies a 2.45 GHz microwave to the isolator 17 described later as a pulsed microwave pulse according to the pulse signal from the microwave pulse control unit 11.

  The microwave pulse is supplied from the microwave oscillator 12 to the processing surface of the workpiece 8 via the isolator 17, the tuner 18, the waveguide 19, the coaxial waveguide 21, and the microwave supply port 22. The coaxial waveguide 21 protrudes from the waveguide 19 via a coaxial waveguide converter (not shown). The microwave supply port 22 is a member such as a dielectric material that transmits microwaves such as quartz. The isolator 17 prevents the reflected wave of the microwave from returning to the microwave oscillator 12. The tuner 18 matches the impedances before and after the tuner 18 so that the reflected wave of the microwave is minimized.

  The workpiece 8 is disposed so as to protrude toward the inside of the processing container 2 with respect to the microwave supply port 22. For example, the workpiece material 8 may be inserted into a groove formed in the microwave supply port 22, or a jig (not shown) that supports the workpiece material 8 may be inserted into the groove.

  A negative voltage electrode 25 for applying a negative bias voltage pulse is electrically connected to the upper end of the workpiece 8 at the upper end of the workpiece 8.

  The negative voltage power supply 15 supplies a negative bias voltage to the negative voltage pulse generator 16 in accordance with an instruction from the controller 6. The negative voltage pulse generator 16 pulses the negative bias voltage supplied from the negative voltage power supply 15. This pulsing process is a process in which the negative voltage pulse generator 16 controls the magnitude, cycle, and duty ratio of the negative bias voltage pulse in accordance with an instruction from the controller 6. A negative bias voltage pulse, which is a pulsed negative bias voltage, is applied to the workpiece 8 held inside the processing vessel 2 via the negative voltage electrode 25.

  Whether the workpiece 8 is a metal substrate or a ceramic or resin is coated with a conductive material, a negative bias voltage is applied to at least the entire processing surface 10 of the workpiece 8. A pulse is applied.

  By controlling the generated microwave pulse and the negative bias voltage pulse to be applied at the same time, the surface wave excited plasma is generated. The microwave is not limited to 2.45 GHz, but may have a frequency of 0.3 GHz to 50 GHz. Further, although a pulsed microwave pulse is supplied, a continuous microwave may be supplied. The negative voltage power supply 15 and the negative voltage pulse generator 16 are examples of the negative voltage application unit of the present invention. The negative voltage electrode 25 is an example of the negative voltage application terminal member of the present invention.

  The microwave control unit 11, the microwave oscillator 12, the microwave power source 13, the isolator 17, the tuner 18, the waveguide 19, and the coaxial waveguide 21 are examples of the microwave supply unit of the present invention. The film forming apparatus 1 may include a negative voltage generating unit that applies a continuous negative bias voltage instead of the pulsed negative bias voltage instead of the negative voltage pulse generating unit 16.

  A radiation thermometer 29 is arranged at a position near the outside of the window 27 provided on the side wall of the processing container 2. The radiation thermometer 29 is electrically connected to the control unit 6. The radiation thermometer 29 receives infrared rays and calculates the intensity of the received infrared rays. The surface temperature of the workpiece 8 is calculated from the calculated infrared intensity. The radiation thermometer 29 outputs the calculated temperature information of the work material 8 to the control unit 6.

  The control unit 6 outputs control signals to the negative voltage power supply 15 and the microwave power supply 13 to control the applied power of the microwave pulse and the applied voltage of the negative voltage pulse. The control unit 6 outputs a control signal to the negative voltage pulse generation unit 16 and the microwave pulse control unit 11, thereby generating the application timing and supply voltage of the pulsed negative bias voltage pulse and the microwave oscillator 12. The supply timing and supply power of the microwave pulse to be controlled are controlled.

  The control unit 6 outputs a flow rate control signal to the gas supply unit 5 to control the supply of the source gas and the inert gas. The control unit 6 outputs a control signal to the pressure adjustment valve 7 based on a pressure signal representing the pressure in the processing container 2 input from the vacuum gauge 26 attached to the processing container 2, and Control the pressure.

[Description of surface wave excitation plasma]
Usually, when generating surface wave excitation plasma, a microwave is supplied along the interface between a plasma having a certain level of electron (ion) density and a dielectric in contact with the plasma. The supplied microwave is propagated as a surface wave with the energy of electromagnetic waves concentrated on this interface. As a result, the plasma in contact with the interface is excited by a high energy density surface wave and further amplified. Thereby, a high density plasma is generated and maintained. However, when this dielectric is replaced with a conductive material, the conductive material does not function as a surface wave waveguide, and preferable surface wave propagation and plasma excitation cannot occur.

  On the other hand, an essentially unipolar charged particle layer, a so-called sheath layer, is formed near the surface of an object in contact with plasma. In the case where the object is a work material 8 having conductivity to which a negative bias voltage is applied, the sheath layer is a layer having a low electron density, that is, positive polarity, and substantially has a relative dielectric constant in the microwave frequency band. It is a layer of ε≈1. For this reason, the sheath thickness of the sheath layer can be increased by making the absolute value of the negative bias voltage to be applied larger than the absolute value of, for example, −100V. That is, the sheath layer expands. This sheath layer acts as a dielectric that propagates surface waves to the interface between the plasma and the object in contact with the plasma.

  Therefore, when a microwave is supplied from the microwave supply port 22 disposed close to one end of the workpiece material 8 and a negative bias voltage is applied to the workpiece material 8, the microwave is separated from the sheath layer and the plasma. It propagates as a surface wave along the interface. As a result, high-density excitation plasma based on surface waves is generated along the processing surface 10 of the workpiece 8 and the holding jig 9. This high-density excitation plasma is the above-described surface wave excitation plasma.

  The electron density of the high-density plasma due to surface wave excitation in the vicinity of the surface of the workpiece 8 reaches 1011 to 1012 cm-3. When the DLC film forming process is performed by plasma CVD using the MVP method, the film forming speed is 3 to 30 (nano m / second), which is 10 to 100 times larger than the case where the DLC film forming process is performed by normal plasma CVD. Therefore, high-speed film formation is possible.

  In this MVP method, the work material 8 is disposed in close contact with the microwave supply port 22, and a sheath layer is formed along the processing surface 10 of the work material 8. A high-density plasma is generated by the microwave propagating as a surface wave along the sheath layer expanded by the negative bias voltage. Since the plasma density is high, the material 8 to be processed is formed at high speed. Since the work material 8 is disposed so as to face the central conductor 21C of the coaxial waveguide 21, the microwaves propagate efficiently in the upward direction.

  The film forming apparatus 1 includes an auxiliary electrode 30 and a positive voltage power source 40. The control unit 6 outputs a control signal to the positive voltage power supply 40 to control the continuous positive voltage supply voltage and the supply timing of the positive voltage. The positive voltage power supply 40 supplies a positive voltage to the auxiliary electrode 30 in accordance with a control signal from the control unit 6. The control unit 6 and the positive voltage power supply 40 are examples of the positive voltage application unit of the present invention. With reference to FIG. 3, an example of supplying a microwave pulse and applying a negative bias voltage and a positive voltage will be described. Details of the supply of the microwave pulse and the application of the negative bias voltage are disclosed in JP-A-2014-51715.

The supply time Tmw of each microwave pulse is expressed by the following equation by the period T1 of the microwave pulse and the duty ratio DMW (Duty of Microwave) of the microwave pulse.
Tmw = T1 * DMW (1)
The application time Tdc of each negative voltage pulse is expressed by the following equation by the negative voltage pulse cycle T2 and the negative voltage pulse duty ratio DSH (duty of sheet).
Tdc = T2 * DSH (2)
Note that the negative voltage pulse may be applied after the microwave pulse is supplied, the microwave pulse may be supplied after the negative voltage pulse is applied, the supply of the microwave pulse and the negative voltage pulse The application may be performed simultaneously. Similarly, the application of the negative voltage pulse may be completed after the supply of the microwave pulse is completed, or the supply of the microwave pulse may be completed after the application of the negative voltage pulse is completed. Alternatively, the end of the supply of the microwave pulse and the end of the application of the negative voltage may be performed simultaneously.

  The positive voltage may be applied during a period in which the supply of the microwave and the application of the negative voltage pulse are performed. That is, a positive voltage may be applied to at least a part of the application time Tdc for each negative voltage pulse. In FIG. 2, a positive voltage is applied during the entire film formation period. The value of the negative bias voltage may be −100 V to −1000 V, and the value of the positive voltage is at a position farther away from the microwave supply port 22 in the Z direction than the electric field strength on the microwave supply port 22 side. It is only necessary that the electric field intensity around the workpiece 8 is increased. For example, it may be + 1V to + 200V. As a result, the sheath layer at the upper end 8U of the work material 8 becomes thicker. Therefore, the attenuation of the density of the plasma generated around the upper end 8U is further reduced.

  The auxiliary electrode 30 will be described in detail with reference to FIG. The auxiliary electrode 30 is formed from a metal material. An insulating member 31 is fixed to the side surface of the negative voltage electrode 25. The auxiliary electrode 30 is fixed to the side surface of the insulating member 31. Therefore, the auxiliary electrode 30 is disposed around the outside of the workpiece 8 disposed so as to protrude from the microwave supply port 22. The auxiliary electrode 30 is a disk extending in the normal direction N from the side surface of the insulating member 31. In the present embodiment, the normal direction N is the direction of the normal line on the side surface of the insulating member 31 and the direction of the normal line on the side surface of the negative voltage electrode 25. The length of the auxiliary electrode 30 in the normal direction N is not particularly limited, but is 2.5 cm as an example. The length of the auxiliary electrode 30 in the normal direction N is preferably increased according to the length of the workpiece 8 in the Z direction. In the present embodiment, the Z direction is the protruding direction of the workpiece 8 and coincides with the upward direction in FIG. As shown in FIG. 3, the auxiliary electrode 30 is provided at a position sandwiching the workpiece 8 with respect to the microwave supply port 22.

  A positive voltage from the positive voltage power supply 40 is applied to the auxiliary electrode 30. The application form of the positive voltage is not particularly limited, but will be described below as a continuous positive voltage. That is, the positive voltage applied to the auxiliary electrode 30 from the positive voltage power supply 40 may be pulsed. When the applied positive voltage has a pulse shape, a positive voltage pulse generator may be provided between the positive voltage power supply 40 and the auxiliary electrode 30 in FIG. The controller 6 may control the application timing and supply voltage of the pulsed positive bias voltage pulse by outputting a control signal to the positive voltage pulse generator.

  As shown in FIG. 3, in the state where a negative bias voltage is applied to the work material 8, an electric force is applied around the upper end 8 </ b> U of the work material 8 by applying a positive voltage to the auxiliary electrode 30. The line becomes dense. The broken line shown in FIG. 3 and FIGS. 5-9 mentioned later shows an electric force line. In other words, the electric field strength is increased around the upper end 8U of the workpiece 8. As a result, when a microwave is supplied in a state where a negative bias voltage is applied to the workpiece material 8 and a positive voltage is applied to the auxiliary electrode 30, the thickness in the normal direction N of the generated sheath layer is: It becomes thicker at the upper end 8U of the work material 8. Specifically, a sheath around the upper end 8U of the workpiece 8 in a state where a negative bias voltage is applied to the workpiece 8 and a microwave is supplied and a positive voltage is applied to the auxiliary electrode 30. The thickness of the layer in the normal direction N is such that the auxiliary electrode 30 is not provided in the film forming apparatus 1, the negative bias voltage is applied to the work material 8, and the upper end of the work material 8 is supplied with microwaves. It is thicker than the thickness in the normal direction N of the sheath layer around 8U. In the present embodiment, the thickness direction of the sheath layer is the normal direction N. That is, the auxiliary electrode 30 extends in the thickness direction of the sheath layer. Moreover, as shown in FIG. 3, the upper end 8U of the workpiece 8 is located on the opposite side to the microwave supply port 22 in the Z direction.

  In the microwave propagating as a surface wave at the interface between the sheath layer and the plasma formed along the processing surface 10 of the workpiece 8, the impedance to the surface wave changes as the thickness of the sheath layer changes. Part of the wave is reflected. In addition, the thinner the sheath layer, the greater the resistance loss that occurs on the processing surface 10 of the workpiece 8. That is, as the sheath layer becomes thinner as the distance from the microwave supply port 22 increases, the amplitude of the surface wave decreases. Therefore, the plasma density of the high-density excitation plasma based on the surface wave decreases as the distance from the microwave supply port 22 increases. As a result, the film thickness formed on the processing surface 10 of the workpiece 8 becomes thinner as the distance from the microwave supply port 22 increases. Moreover, since the plasma density of the high-density excitation plasma decreases as the distance from the microwave supply port 22 increases, the film quality of the film formed on the processing surface 10 of the workpiece material 8 may also decrease. That is, as the distance from the microwave supply port 22 increases, the processing capacity of the workpiece 8 on the processing surface 10 decreases. On the other hand, in the first embodiment, by applying a positive voltage to the auxiliary electrode 30, the electric field strength is increased around the upper end 8 </ b> U of the work material 8. When the electric field strength increases, the electrons are strongly pushed in the direction opposite to the workpiece material 8 (the direction of the plasma region), and the electron density further decreases. As a result, the sheath layer is enlarged, and the reflection of surface waves or the loss on the surface of the workpiece 8 is reduced. Therefore, a decrease in the plasma density of the high-density excitation plasma based on the surface wave propagating through the more enlarged sheath layer / plasma interface is reduced. As a result, it is possible to reduce the decrease in the film thickness formed on the processing surface 10 of the workpiece 8 as the distance from the microwave supply port 22 increases. Further, the possibility that the film quality of the film formed on the processing surface 10 of the work material 8 is lowered can be reduced. That is, as the distance from the microwave supply port 22 increases, it is possible to reduce a decrease in processing capability of the workpiece 8 on the processing surface 10.

  In the first embodiment, a positive voltage is applied to the auxiliary electrode 30, but the auxiliary electrode 30 may be electrically connected to the processing container 2, for example. In other words, the auxiliary electrode 30 may be connected to GND. In the film forming apparatus in which the auxiliary electrode 30 is not provided, the electric lines of force directed to the workpiece 8 to which a negative bias voltage is applied mainly extend from the processing container 2 connected to the GND. Therefore, the electric lines of force around the upper end 8U of the work material 8 are sparse. On the other hand, if a positive voltage is not applied to the auxiliary electrode 30 and the GND connection is established, the lines of electric force mainly go from the auxiliary electrode 30 to the workpiece 8 to which a negative bias voltage is applied. Therefore, the electric lines of force around the upper end 8U of the work material 8 are dense. That is, even if the auxiliary electrode 30 is GND-connected, the electric field strength around the upper end 8U of the workpiece 8 is increased.

  FIG. 4 shows experimental data of the film thickness distribution in the Z direction when the auxiliary electrode 30 is not provided in the film forming apparatus 1, when a positive voltage is applied to the auxiliary electrode 30, and when the auxiliary electrode 30 is connected to GND. . In the graph shown in FIG. 4, the horizontal axis indicates the position in the Z direction of the work material 8 with the position of the lower end 8B of the work material 8 as the origin. That is, the larger the value, the farther from the microwave supply port 22. A vertical axis | shaft shows the film thickness with respect to the film thickness of the position 20 mm away from the lower end 8B of the to-be-processed material 8 in the Z direction. That is, the larger the value, the larger the film thickness distribution.

  The conditions for the experiment are described below. The workpiece 8 is SUS304 having a diameter of 10 mm and a length of 100 mm. The auxiliary electrode 30 is a disc-shaped SUS304 having a diameter of 50 mm and a thickness of 5 mm. The processing vessel 2 was supplied with Ar at 200 sccm, CH4 at 40 sccm, and TMS at 20 sccm, and the pressure was controlled to 75 Pa. The microwave pulse is controlled so that the power is 0.5 kW, the frequency is 500 Hz, and the duty ratio is 60%, and the negative bias voltage pulse is controlled so that the frequency is 500 Hz and the voltage value is −400V. It was. The positions at which the film thickness is measured are positions 20 mm away from the lower end 8B of the workpiece 8 in the Z direction, positions 55 mm away, and positions 90 mm away. In the graph shown in FIG. 4, the measurement data is connected by an approximate curve.

  Data indicated by a solid line A indicates experimental data when the auxiliary electrode 30 is not provided in the film forming apparatus 1. Data indicated by a two-dot chain line B is experimental data when a voltage of +200 V is applied to the auxiliary electrode 30. Data indicated by a one-dot chain line C is experimental data when the auxiliary electrode 30 is GND-connected.

  As indicated by the data of the solid line A, when the auxiliary electrode 30 is not provided in the film forming apparatus 1, the film thickness at a position 55 mm away from the lower end 8B in the Z direction is the film thickness at a position 20 mm away from the lower end 8B. 19% decrease. Further, the film thickness at a position 90 mm away from the lower end 8B in the Z direction is reduced by 45% with respect to the film thickness at a position 20 mm away from the lower end 8B.

  As shown by the data of the two-dot chain line B, when a voltage of +200 V is applied to the auxiliary electrode 30, the film at a position 55 mm away from the lower end 8B in the Z direction with respect to the film thickness at a position 20 mm away from the lower end 8B. The thickness is reduced by 4%. The film thickness at a position 90 mm away from the lower end 8B in the Z direction is reduced by 10% with respect to the film thickness at a position 20 mm away from the lower end 8B.

  As indicated by the alternate long and short dash line C, when the auxiliary electrode 30 is connected to GND, the film thickness at a position 55 mm away from the lower end 8B in the Z direction is 6% of the film thickness at a position 20 mm away from the lower end 8B. Decrease. Further, the film thickness at a position 90 mm away from the lower end 8B in the Z direction is reduced by 18% with respect to the film thickness at a position 20 mm away from the lower end 8B.

  As indicated by the data of the solid line A, the data of the two-dot chain line B, and the data of the one-dot chain line C, a voltage of +200 V is applied to the auxiliary electrode 30 as compared with the case where the auxiliary electrode 30 is not provided in the film forming apparatus 1. In this case, and when the auxiliary electrode 30 is GND-connected, it is possible to reduce a decrease in film thickness that is further away from the film thickness on the lower end 8B side in the Z direction, that is, on the side opposite to the microwave supply port 22. In other words, the film thickness distribution in the Z direction of the film thickness formed on the processing surface 10 of the workpiece 8 is reduced. Further, when a voltage of +200 V is applied to the auxiliary electrode 30 as compared with the case where the auxiliary electrode 30 is connected to the GND, the film is separated in the Z direction from the film thickness on the lower end 8B side. The decrease in the film thickness on the opposite side can be further reduced. In other words, the film thickness distribution in the Z direction of the film thickness formed on the processing surface 10 of the workpiece 8 is further reduced.

  That is, as indicated by the data of the solid line A, the data of the two-dot chain line B, and the data of the one-dot chain line C, the electric field strength around the upper end 8U of the work material 8 is applied with a positive voltage or GND connection By providing the auxiliary electrode 30, the electric field intensity around the upper end 8U becomes stronger with respect to the position 20 mm away from the lower end 8B in the Z direction and 55 mm away from the Z direction. As a result, the thickness of the sheath layer formed around the upper end 8U with respect to the thickness of the sheath layer formed on the microwave supply port 22 side and the thickness of the sheath layer formed in the central portion of the workpiece material 8 in the Z direction. Can be said to have been reduced by providing the auxiliary electrode 30 to which a positive voltage is applied or is connected to GND.

<Modification 1>
Although the auxiliary electrode 30 extended in the normal direction N from the side surface of the insulating member 31, it is not restricted to this. For example, the auxiliary electrode 30 </ b> A illustrated in FIG. 5 is curved toward the microwave supply port 22 as it goes in the normal direction N. In this case, since the end of the curved auxiliary electrode 30 approaches the workpiece material 8, the electric field strength in the region surrounded by the auxiliary electrode 30 and the workpiece material 8 is further increased. Thereby, the electric field intensity around the upper end 8U arranged at the position farthest from the microwave supply port 22 becomes stronger. As a result, the sheath layer generated around the upper end 8U becomes thicker. Therefore, the attenuation of the density of the plasma generated around the upper end 8U is further reduced. Further, as shown in FIG. 5, the lines of electric force become dense not only around the upper end U of the workpiece material 8 but also around the center of the workpiece material 8. As a result, the decrease in the electric field strength around the central portion in the Z direction of the workpiece 8 is reduced with respect to the electric field strength on the microwave supply port 22 side. Therefore, a decrease in the thickness of the sheath layer formed in the center portion in the Z direction of the workpiece 8 relative to the thickness of the sheath layer formed on the microwave supply port 22 side is reduced. Therefore, the processing surface of the work material 8 is provided by providing the auxiliary electrode 30 that is curved toward the microwave supply port 22 and is applied with a positive voltage or is GND-connected in the normal direction N. 10, the film thickness distribution in the Z direction of the film formed on the film 10 is further reduced.

<Modification 2>
In the normal direction N, the same voltage positive voltage is applied to the auxiliary electrode 30 at a position close to the negative voltage electrode 25 and a position far from the negative voltage electrode 25, but the auxiliary electrode 30 is not limited thereto. The auxiliary electrode 30B shown in FIG. 6 includes a first auxiliary electrode 30B1, a second auxiliary electrode 30B2, and a third auxiliary electrode 30B3. An insulating member 31B1 is provided between the first auxiliary electrode 30B1 and the second auxiliary electrode 30B2. An insulating member 31B2 is provided between the second auxiliary electrode 30B2 and the third auxiliary electrode 30B3. The first auxiliary electrode 30B1, the second auxiliary electrode 30B2, and the third auxiliary electrode 30B3 are disks having different outer diameters, and have a hollow shape. The inner peripheral surface of the first auxiliary electrode 30B1 is fixed to the insulating member 31, and the outer peripheral surface is fixed to the insulating member 31B1. The inner peripheral surface of the second auxiliary electrode 30B2 is fixed to the insulating member 31B1, and the outer peripheral surface is fixed to the insulating member 31B2. The inner peripheral surface of the third auxiliary electrode 30B3 is fixed to the insulating member 31B2.

  The positive voltage V3 applied to the third auxiliary electrode 30B3 is desirably larger than the positive voltage V1 applied to the first auxiliary electrode 30B1. The positive voltage V2 applied to the second auxiliary electrode 30B2 will be described as a value between the positive voltage V1 and the positive voltage V3, but may be the same as the positive voltage V1 or the same as the positive voltage V3. good. Further, the positive voltage V2 may be a value smaller than V1, a value larger than V3, or zero.

  As shown in FIG. 6, when the positive voltage V3 applied to the third auxiliary electrode 30B3 is larger than the positive voltage V1 applied to the first auxiliary electrode 30B1, the position is farthest from the microwave supply port 22. The electric field intensity around the upper end 8U to be arranged becomes stronger. As a result, the sheath layer generated around the upper end 8U becomes thicker. Therefore, the attenuation of the density of the plasma generated around the upper end 8U is further reduced. Further, the electric lines of force become dense not only around the upper end U of the work material 8 but also around the center of the work material 8. As a result, the decrease in the electric field strength around the central portion in the Z direction of the work material 8 is reduced with respect to the electric field strength on the microwave supply port 22 side. Therefore, a decrease in the thickness of the sheath layer formed in the center portion in the Z direction of the workpiece 8 relative to the thickness of the sheath layer formed on the microwave supply port 22 side is reduced. Therefore, by providing the auxiliary electrode 30 in which the positive voltage V3 applied to the third auxiliary electrode 30B3 is larger than the positive voltage V1 applied to the first auxiliary electrode 30B1, the processing surface 10 of the material 8 to be processed is provided. The film thickness distribution in the Z direction of the film thickness to be formed is further reduced.

Second Embodiment
Hereinafter, a second embodiment of the film forming apparatus 1 of the present invention will be described in detail with reference to the drawings. In the first embodiment, the auxiliary electrode 30 extends in the thickness direction of the sheath layer, that is, in the normal direction N. However, the auxiliary electrode 30C in the second embodiment projects the workpiece 8 from the microwave supply port 22. It is arranged along the direction, that is, the Z direction. Hereinafter, the same structure as 1st Embodiment attaches | subjects the same figure number as 1st Embodiment, and demonstrates a structure different from 1st Embodiment.

  As shown in FIG. 7, the auxiliary electrode 30 </ b> C is disposed along the Z direction around the outside of the workpiece 8. The auxiliary electrode 30C is formed from a metal member having a hollow cylindrical shape. The auxiliary electrode 30 </ b> C is a fixing member (not shown), and the position is fixed with respect to the microwave supply port 22. The material 8 to be processed is inserted into the hollow cylindrical auxiliary electrode 30 </ b> C and fixed to the groove formed in the microwave supply port 22. It is desirable that the auxiliary electrode 30C be arranged so that the upper end 30CU of the auxiliary electrode 30C in the Z direction has a shorter distance from the workpiece 8 than the lower end 30CB. For example, the distance between the upper end 30CU and the work material 8 may be 20 mm to 30 mm. The distance between the lower end 30CB and the workpiece 8 may be 40 mm to 50 mm. As shown in FIG. 7, when an auxiliary electrode 30 </ b> C to which a positive voltage is applied or is GND-connected and arranged along the Z direction is provided, the upper end arranged at the position farthest from the microwave supply port 22. Electric field lines around 8U become dense. Therefore, the electric field intensity around the upper end 8U is increased. As a result, the sheath layer generated around the upper end 8U becomes thick. Therefore, the attenuation of the density of the plasma generated around the upper end 8U is reduced. When the auxiliary electrode 30C is arranged so that the distance between the upper end 30CU and the workpiece 8 is shorter than the lower end 30CB, the lines of electric force around the upper end 8U become dense. Therefore, the electric field intensity around the upper end 8U becomes stronger. As a result, the sheath layer generated around the upper end 8U becomes thicker. Therefore, the attenuation of the density of the plasma generated around the upper end 8U is further reduced.

<Modification 3>
The auxiliary electrode 30C shown in FIG. 7 is formed of one metal member having a hollow cylindrical shape, but is not limited thereto. As shown in FIG. 8, the auxiliary electrode 30D includes a first auxiliary electrode 30D1, a second auxiliary electrode 30D2, and a third auxiliary electrode 30D3. The first auxiliary electrode 30D1, the second auxiliary electrode 30D2, and the third auxiliary electrode 30D3 are all formed from a metal member having a hollow cylindrical shape. The first auxiliary electrode 30 </ b> D <b> 1, the second auxiliary electrode 30 </ b> D <b> 2, and the third auxiliary electrode 30 </ b> D <b> 3 are all fixing members (not shown), and their positions are fixed with respect to the microwave supply port 22. The workpiece 8 is inserted into the first auxiliary electrode 30D1, the second auxiliary electrode 30D2, and the third auxiliary electrode 30D3 each having a hollow cylindrical shape, and is fixed to a groove formed in the microwave supply port 22. The

  The first auxiliary electrode 30D1, the second auxiliary electrode 30D2, and the third auxiliary electrode 30D3 are arranged along the Z direction around the outside of the material 8 to be processed, and a positive voltage having the same value is applied thereto. The distance between the first auxiliary electrode 30D1 and the work material 8 is longer than the distance between the second auxiliary electrode 30D2 and the work material 8, and the distance between the second auxiliary electrode 30D2 and the work material 8 is the third auxiliary. It is longer than the distance between the electrode 30D2 and the material 8 to be processed. For example, the distance between the first auxiliary electrode 30D1 and the workpiece 8 may be 45 mm to 50 mm. The distance between the second auxiliary electrode 30D2 and the workpiece 8 may be 32 mm to 37 mm. The distance between the third auxiliary electrode 30D3 and the workpiece 8 may be 20 mm to 25 mm.

  As shown in FIG. 8, when an auxiliary electrode 30 </ b> D to which a positive voltage is applied or is GND-connected and disposed along the Z direction is provided, the upper end disposed at the farthest position from the microwave supply port 22. Electric field lines around 8U become dense. Therefore, the electric field intensity around the upper end 8U is increased. As a result, the sheath layer generated around the upper end 8U becomes thick. Therefore, the attenuation of the density of the plasma generated around the upper end 8U is reduced. The distance between the first auxiliary electrode 30D1 and the work material 8 is longer than the distance between the second auxiliary electrode 30D2 and the work material 8, and the distance between the second auxiliary electrode 30D2 and the work material 8 is the first distance. 3 Since the distance between the auxiliary electrode 30D2 and the workpiece 8 is longer, the electric lines of force around the upper end 8U become denser. Therefore, the electric field intensity around the upper end 8U becomes stronger. As a result, the sheath layer generated around the upper end 8U becomes thicker. Therefore, the attenuation of the density of the plasma generated around the upper end 8U is further reduced.

<Modification 4>
Although the auxiliary electrode 30D shown in FIG. 8 includes the first auxiliary electrode 30D1, the second auxiliary electrode 30D2, and the third auxiliary electrode 30D3 that are different in distance from the workpiece 8, the present invention is not limited thereto. As shown in FIG. 9, the auxiliary electrode 30E includes a first auxiliary electrode 30E1, a second auxiliary electrode 30E2, and a third auxiliary electrode 30E3. The first auxiliary electrode 30E1, the second auxiliary electrode 30E2, and the third auxiliary electrode 30E3 are all formed from a metal member having a hollow cylindrical shape. The first auxiliary electrode 30E1, the second auxiliary electrode 30E2, and the third auxiliary electrode 30E3 are all fixing members (not shown), and their positions are fixed with respect to the microwave supply port 22. The workpiece 8 is inserted into the first auxiliary electrode 30E1, the second auxiliary electrode 30E2, and the third auxiliary electrode 30E3 each having a hollow cylindrical shape, and is fixed to a groove formed in the microwave supply port 22. The

  The first auxiliary electrode 30E1, the second auxiliary electrode 30E2, and the third auxiliary electrode 30E3 are disposed along the Z direction around the outside of the workpiece 8. The positive voltage V2 applied to the second auxiliary electrode 30E2 is higher than the positive voltage V1 applied to the first auxiliary electrode 30E1, and the positive voltage applied to the third auxiliary electrode 30E3 is higher than the positive voltage V2. V3 is large. For example, the positive first voltage V1 may be 1V to 10V. The positive second voltage V2 may be 100V to 110V. The positive third voltage V3 may be 190V to 200V.

  As shown in FIG. 9, the positive voltage V2 applied to the second auxiliary electrode 30E2 is higher than the positive voltage V1 applied to the first auxiliary electrode 30E1, and the third auxiliary electrode 30E3 is higher than the positive voltage V2. Since the positive voltage V3 applied to is large, the electric lines of force around the upper end 8U become denser. Therefore, the electric field intensity around the upper end 8U becomes stronger. As a result, the sheath layer generated around the upper end 8U becomes thicker. Therefore, the attenuation of the density of the plasma generated around the upper end 8U is further reduced.

<Modification 5>
In the first embodiment and the second embodiment, the negative voltage electrode 25 is connected to the upper end 8U of the material 8 to be processed, but is not limited thereto. For example, the negative voltage electrode 25 may be connected to the central portion of the workpiece material 8 in the Z direction, or may be connected to the lower end of the workpiece material 8. In the first embodiment, the auxiliary electrode 30 is fixed with respect to the negative voltage electrode 25. However, when the negative voltage electrode 25 is connected to the central portion or the lower end in the Z direction of the workpiece 8, the auxiliary electrode 30 should just be fixed to the upper end side of the workpiece 8 by the positioning member which is not shown in figure.

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 2 Processing container 6 Control part 8 Work material 8U Upper end 8B Lower end 10 Processing surface 11 Microwave pulse control part 12 Microwave oscillator 13 Microwave power supply 15 Negative voltage power supply 16 Negative voltage pulse generation part 17 Isolator 18 Tuner 21 Coaxial waveguide 22 Microwave supply port 25 Negative voltage electrode 30, 30A, 30B, 30C, 30D, 30E Auxiliary electrode 31 Insulating member

Claims (9)

A microwave supply section for supplying microwaves for generating plasma along the processing surface of the conductive material to be processed;
A negative voltage application unit that applies a negative bias voltage to the workpiece material to expand a sheath layer along the processing surface of the workpiece material;
A microwave supply port for propagating the microwave supplied from the microwave supply unit to the expanded sheath layer;
A negative voltage application terminal member that applies a negative bias voltage applied by the negative voltage application unit to the workpiece material that protrudes from the microwave supply port;
An electrode for enlarging the thickness of the sheath layer formed on the side opposite to the microwave supply port side, to which a positive voltage connected to GND or supplied from a positive voltage application unit is applied, and Auxiliary electrodes arranged around the outside of the workpiece material arranged to protrude,
A film forming apparatus comprising: The film forming apparatus according to claim 1, wherein the auxiliary electrode is provided at a position sandwiching the workpiece material with respect to the microwave supply port. The film forming apparatus according to claim 2, wherein the auxiliary electrode extends in a direction perpendicular to a protruding direction of the material to be processed . The film forming apparatus according to claim 3, wherein a larger positive voltage value is applied to the auxiliary electrode as the distance from the workpiece material becomes longer . 5. The film forming apparatus according to claim 3, wherein the auxiliary electrode is curved toward the microwave supply port as the distance from the workpiece material becomes longer . The film forming apparatus according to claim 1, wherein the auxiliary electrode is disposed along a protruding direction of the material to be processed with respect to the microwave supply port. The film forming apparatus according to claim 6, wherein the auxiliary electrode is disposed such that a distance from the workpiece material is shorter on the opposite side than on the microwave supply port side. 8. The film forming apparatus according to claim 6, wherein a positive voltage having a larger value is applied to the auxiliary electrode on the opposite side than on the microwave supply port side. The positive voltage applied to the auxiliary electrode is applied during at least a part of a period in which a negative bias voltage is applied by the negative voltage application unit and a microwave is supplied by the microwave supply unit. Item 9. The film forming apparatus according to any one of Items 1 to 8.

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