JP2010182553A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus which has an electric conductor work that is hard to be damaged and in which both sides of the electric conductor work can be plasma-processed simultaneously. <P>SOLUTION: The plasma processing apparatus 102 includes an upper electrode 104, a lower electrode 114, a pulse power supply 124 to output electric pulses between a first power output end 126 and a second power output end 128, a first wiring 130 to connect the first power output end 126 and the upper electrode 104, a second wiring 132 to connect the second power output end 128 and the lower electrode 114, and a transport grounding mechanism 134 that makes a work W pass through a plasma region 1902 and to ground the work W. The pulse power supply 124 is a floating electric power supply in which the first power output end 126 and the second power output end 128 are insulated from the ground, and the first electrode 104, the second electrode 114, the first wiring 130, and the second wiring 132 as well are insulated from the ground. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus for plasma processing a conductor work.

  2. Description of the Related Art Conventionally, there has been known a plasma processing apparatus that performs plasma processing on a conductive workpiece by applying plasma to the conductive workpiece.

  For example, the plasma processing apparatus of Patent Document 1 allows a plasma region to pass through a conductor work in contact with a flat surface of an electrode structure (lower electrode 4) including a grounded electrode, and plasma is applied to the conductor work. Let Patent document 1 mentions covering an electrode with a dielectric barrier.

  Moreover, the plasma processing apparatus of patent document 2 passes a plasma area | region through a conductor workpiece in the state which contacted the cylindrical surface of the electrode structure (electrode unit 20) provided with the earthed electrode, and plasma acts on a conductor workpiece. Let Patent document 2 also mentions covering an electrode with a dielectric barrier.

JP 2000-147207 A JP 2004-327394 A

  However, in the plasma processing apparatuses of Patent Documents 1 and 2, since the conductor work is in wide contact with the electrode structure, the conductor work is easily damaged. Moreover, since plasma acts only on one side of the conductor workpiece, both sides of the conductor workpiece cannot be plasma-treated at the same time.

  The present invention has been made to solve these problems, and an object of the present invention is to provide a plasma processing apparatus in which a conductor workpiece is hardly damaged and both surfaces of the conductor workpiece are subjected to plasma processing simultaneously.

  In order to solve the above-mentioned problem, the invention of claim 1 is a plasma processing apparatus for plasma processing a conductor work, wherein the first electrode insulated from the ground, the second electrode insulated from the ground, A floating power source having a first output terminal and a second output terminal insulated from ground and outputting an electric pulse between the first output terminal and the second output terminal; A first wiring connecting the output terminal and the first electrode; a second wiring insulated from ground; and connecting the second output terminal and the second electrode; and The plasma region is provided outside a plasma region where plasma is generated by applying an electric pulse between one electrode and the second electrode, and is separated from the first electrode and the second electrode. Lead And a conveying ground mechanism for grounding the conductive workpiece with passing the body work.

  According to a second aspect of the present invention, in the plasma processing apparatus of the first aspect, the transfer grounding mechanism includes a roller in which the grounded conductor is exposed to the cylindrical surface and rotates around the rotation axis.

  According to a third aspect of the present invention, in the plasma processing apparatus according to the first or second aspect, the first electrode and the second electrode are conductive plates perpendicular to a conveying direction of the conductive work.

  According to a fourth aspect of the present invention, there is provided the plasma processing apparatus according to the first or second aspect, wherein the first electrode and the second electrode are a conductor rod or a conductor pipe perpendicular to a direction in which a conductor workpiece is conveyed. is there.

  According to a fifth aspect of the present invention, in the plasma processing apparatus of any one of the first to fourth aspects, a first dielectric barrier that covers the first electrode and a second dielectric that covers the second electrode A dielectric barrier, and the transfer grounding mechanism allows the plasma region to pass through the conductor work in a state of being separated from the first dielectric barrier and the second dielectric barrier.

  According to invention of Claim 1 thru | or 5, since a conductor workpiece does not contact a 1st electrode and a 2nd electrode, damage to a conductor workpiece is suppressed. Moreover, since plasma acts simultaneously on both surfaces of the conductor workpiece, both surfaces of the conductor workpiece are subjected to plasma treatment at the same time.

  According to the invention of claim 2, the conductor work is transported and grounded with a simple configuration.

  According to the third to fourth aspects of the invention, since the capacitance between the first electrode and the second electrode is reduced, the disturbance of the waveform of the electric pulse is suppressed.

  According to the invention of claim 5, since arc discharge is suppressed, the uniformity of plasma processing is improved.

It is a schematic diagram of a plasma processing apparatus. It is a perspective view of an electrode structure. It is a perspective view of the electrode structure concerning another example. It is a perspective view of a processing gas supply body. It is a figure which shows the voltage waveform of the electric pulse which IES power supply and CES power supply generate | occur | produce. It is a figure which shows the electric current waveform of the electric pulse which IES power supply and CES power supply generate | occur | produce. It is a figure which shows the waveform of the product of the voltage and electric current of the electric pulse which IES power supply and CES power supply generate | occur | produce. It is a circuit diagram of an IES power supply. It is a figure explaining the measurement point of a contact angle.

{Outline of plasma processing apparatus 102}
FIG. 1 is a schematic diagram of the plasma processing apparatus 102. FIG. 1 shows a cross section of the main part of the reactor of the plasma processing apparatus 102 and an electric system that supplies electric power to the reactor in a floating manner.

  The plasma processing apparatus 102 causes a plasma region 1902 in which plasma is generated to pass through a grounded work W, thereby causing plasma to act on both surfaces of the work W at the same time, and plasma processing is performed on both surfaces of the work W simultaneously. Plasma treatment includes cleaning to remove contamination attached to the surface, etching to erode the surface, ashing to ash the fluorine compound film and other films formed on the surface, modification to improve the wettability of the surface, etc. There is a process to change the state of.

{Work W}
The workpiece W to be subjected to plasma processing by the plasma processing apparatus 102 is a conductive metal plate or sheet such as a single metal such as aluminum or an alloy such as stainless steel.

  Not only the work W whose entirety is a conductor but also the work W whose surface is a conductor is an object of plasma treatment. For example, a workpiece W in which a conductive film such as copper is formed on the main surface of an insulating plate such as glass epoxy or ceramics or an insulating sheet such as polyimide is also an object of plasma processing.

  Not only the flat workpiece W but also the workpiece W having irregularities on the main surface or the workpiece W in which the through holes are formed are the targets of the plasma processing. For example, a mask in which an opening is formed, a nozzle plate in which an ejection port is formed, and the like are also objects of plasma processing.

{Structure of plasma processing apparatus 102}
As shown in FIG. 1, the plasma processing apparatus 102 includes an upper electrode 104, an upper dielectric barrier 106 that covers the upper electrode 104, an upper electrode structure 108 that includes the upper electrode 104 and the dielectric barrier 106, and a workpiece W. An upper processing gas supply body 112 for supplying a processing gas to the gap 110 of the substrate, a lower electrode 114, a lower dielectric barrier 116 covering the lower electrode 114, and a lower electrode structure 118 including the lower electrode 114 and the dielectric barrier 116. A lower processing gas supply body 122 that supplies a processing gas to a gap 120 between the first output end 126 and the second output end 128, a first power source 124 that outputs an electrical pulse, The first wiring 130 that connects the output terminal 126 and the upper electrode 104, and the second wiring 132 that connects the second output terminal 128 and the lower electrode 114. , And a conveying ground mechanism 134 for grounding the workpiece W is passed through the plasma region 1902 in the workpiece W.

{Floating power supply}
The pulse power supply 124 is a floating power supply in which the first output terminal 126 and the second output terminal 128 are insulated from the ground, and the first electrode 104, the second electrode 114, the first wiring 130, and the second power supply The wiring 132 is also insulated from the ground. As a result, the potential difference between the upper electrode 104 and the lower electrode 114 is determined by the output voltage V _pls of the pulse power supply 124, but the potential difference V _pe between the grounded workpiece W and the upper electrode 104 is different from that between the workpiece W and the upper electrode 104. The potential difference V _en between the workpiece W and the lower electrode 114 varies depending on the distance between the workpiece W and the lower electrode 114. This means that by adjusting the position of the workpiece W, the degree of plasma treatment on the upper surface of the workpiece W facing the upper electrode 104 and the lower surface of the workpiece W facing the lower electrode 114 can be freely adjusted.

{Electric pulse}
It is desirable that the electric pulse repeatedly applied between the upper electrode 104 and the lower electrode 114 from the pulse power source 124 is an electric pulse having a fast rise that generates a streamer discharge in the gaps 110 and 120.

  The electric pulse for generating the streamer discharge has a peak voltage of approximately 10 to 100 kV, a full width at half maximum (FWHM) of approximately 100 to 50000 ns, and a time rise rate dV / dt of rising voltage of approximately 10 to 500 kV / It is an electric pulse with μs and a frequency of approximately 1 to 50 kHz. The electric pulse may be a unipolar electric pulse whose polarity does not change, or may be a bipolar electric pulse whose polarity changes alternately.

  When the streamer discharge is generated in the gaps 110 and 120, as shown in FIG. 1, plasmas 136 and 138 that emit light in the form of streaks that spread from the upper electrode structure 108 and the lower electrode structure 118 toward the workpiece W are formed. Is observed. On the other hand, when glow discharge is generated in the gaps 110 and 120, the plasmas 136 and 138 that emit light in a streak shape are not observed.

  In the above description, the range of the half-value width or the like is “substantially” because the structure and material of the upper electrode structure 108 and the lower electrode structure 118, the distance between the gaps 110 and 120, the pressure of the processing gas, and the like. This is because, depending on the specific configuration, the range such as the half width at which streamer discharge occurs may be wider than the above range. Therefore, it is desirable to determine whether or not the discharge is a streamer discharge by observing the actual discharge.

{Arrangement}
As shown in FIG. 1, the upper electrode structure 108 and the upper process gas supply body 112 are provided above the transfer path 140 for the workpiece W, and the lower electrode structure 118 and the lower process gas supply body 122 are transferred to the transfer path 140. Is provided below. The upper electrode structure 108 and the lower electrode structure 118 face each other with the transfer path 140 interposed therebetween, and the upper process gas supply body 112 and the lower process gas supply body 122 face each other with the transfer path 140 interposed therebetween.

  The upper processing gas supply body 112 is provided on the upstream side of the transport path 140 (hereinafter referred to as “transport path upstream side”), and the upper electrode structure 108 is disposed on the downstream side of the transport path 140 (hereinafter referred to as “transport path downstream side”). "). The lower processing gas supply body 122 is provided on the upstream side of the transport path, and the lower electrode structure 118 is provided on the downstream side of the transport path. The plasma processing apparatus 102 shown in FIG. 1 includes two upper electrode structures 108 and two lower electrode structures 118. However, the number of upper electrode structures 108 may be increased or decreased. The number of the structures 118 may be increased or decreased.

{Electrode structure 152}
FIG. 2 is a schematic diagram of an electrode structure 152 used as the upper electrode structure 108 and the lower electrode structure 118. FIG. 2 is a perspective view of the electrode structure 152.

  As shown in FIGS. 1 and 2, the electrode structure 152 includes an electrode 154 that becomes the upper electrode 104 and the lower electrode 114, and a dielectric barrier 156 that becomes the upper dielectric barrier 106 and the lower dielectric barrier 116.

  The electrode 154 is a conductive plate made of stainless steel, aluminum, copper, or the like. The electrode 154 is installed so that it is perpendicular to the transfer direction of the workpiece W, that is, the normal direction of the main surface is the transfer direction of the workpiece W. Thereby, since the electrostatic capacitance between the upper electrode 104 and the lower electrode 114 decreases, the disturbance of the waveform of the electric pulse is suppressed. The lower end of the upper electrode 104 is parallel to the upper end of the lower electrode 114. Thereby, streamer discharge is uniformly generated, and the surface of the workpiece W is processed uniformly. When the entire width direction of the workpiece W is processed, it is desirable that the upper electrode 104 and the lower electrode 114 are wider than the workpiece W. This is because the surface treatment is uniformly performed to the periphery of the workpiece W. When a part of the workpiece W in the width direction is processed, the widths of the upper electrode 104 and the lower electrode 114 are determined according to the width to be processed. The plate thickness of the upper electrode 104 and the lower electrode 114 is preferably about 1 to 20 mm.

  The dielectric barrier 156 is a sheath of an insulator (solid dielectric) such as quartz or alumina. The dielectric barrier 156 is formed with a receiving hole having a substantially same three-dimensional shape as the electrode 154. The electrode 154 is accommodated in the accommodation hole in parallel with the main surface of the dielectric barrier 156. Since the main contribution to the generation of the streamer discharge is in the vicinity of the end face of the electrode 154 near the gaps 110 and 120, the dielectric barrier 156 is located in the vicinity of the end face of the electrode 154 near the gaps 110 and 120. Covering is sufficient. However, the dielectric barrier 156 may cover the entire electrode 154 or substantially the whole. Dielectric barrier 156 protects electrode 154 from plasmas 136 and 138. In addition, since the arc discharge is suppressed by the dielectric barrier 156, the uniformity of the plasma processing is improved.

  The thickness t1 of the portion covering the end face of the dielectric barrier 156 near the gaps 110 and 120 of the electrode 154 is preferably about 0.5 to 5 mm. This is because if the thickness t1 is less than this range, arc discharge tends to occur, and if the thickness t1 is more than this range, the capacitance between the upper electrode 104 and the lower electrode 114 increases and the upper electrode is increased. This is because it tends to be difficult to apply an electrical pulse that rises quickly between the gate 104 and the lower electrode 114. Further, it is desirable that the thickness t2 of the portion covering the main surface of the electrode 154 of the dielectric barrier 156 is approximately 2 to 20 mm. This is because if the thickness t2 is less than this range, the overlap of the bottoms of the plasmas 136 and 138 tends to be too large, and if it exceeds this range, the gap between the plasmas 136 and 138 tends to be too large.

  FIG. 3 is a schematic diagram of an electrode structure 252 that can be employed instead of the electrode structure 152. FIG. 3 is a perspective view of the electrode structure 252.

  As shown in FIG. 3, an electrode structure 252 is used in which an electrode 254 having a round shape of a conductor or a round pipe is covered with a dielectric barrier 256 which is a round pipe of an insulator. The electrode structure 252 may be installed so that the extending direction of the electrode 204 is perpendicular to the conveying direction of the workpiece W. However, the electrode structure 152 has an advantage over the electrode structure 252 that it is easy to manufacture.

{Processing gas supplier 162}
FIG. 4 is a schematic diagram of the processing gas supply 162 used as the upper processing gas supply 112 and the lower processing gas supply 122. FIG. 4 is a perspective view of the processing gas supply body 162.

  As shown in FIG. 4, the processing gas supply body 162 has a substantially rectangular parallelepiped outer shape, and in the inside thereof, a gas reservoir 1620 for retaining the processing gas and a processing gas from the first surface 1622 to the gas reservoir 1620. A flow path 1624 for guiding the processing gas and a flow path 1628 for guiding the processing gas from the gas reservoir 1620 to the second surface 1626 are formed. In addition, a shower plate 164 is installed in the processing gas supply body 162 in contact with the gas reservoir 1620. In the shower plate 164, through holes having a diameter of 0.1 to 1 mm are regularly formed at intervals of 1 to 20 mm. Instead of the shower plate 164, a pressure loss member having a large number of through holes, for example, a mesh laminate or a ceramic porous body may be employed.

  The processing gas supply 162 passes through the flow path 1624, the gas reservoir 1620, the shower plate 164 and the flow path 1628 in order through the processing gas supplied from the processing gas supply source, and makes the flow of the processing gas uniform. A processing gas is ejected from an outlet 1630 having a shape.

{Process gas composition}
The processing gas is desirably a gas mainly composed of nitrogen gas, and is desirably a gas composed of only nitrogen gas or a mixed gas composed of nitrogen gas and oxygen gas.

{Transport grounding mechanism 134}
The transport ground mechanism 134 holds the workpiece W in a state of being separated from the upper electrode structure 108 and the lower electrode structure 118, and moves the plasma region 192 in the gap 1904 between the upper electrode structure 108 and the lower electrode structure 118 to the workpiece W. Rollers 172, 174, and 176 are provided. The roller 172 is installed on the upstream side of the conveyance path with respect to the gap 1904, and the rollers 174 and 176 are grounded on the downstream side of the conveyance path with respect to the gap 1904. When the workpiece W is a rigid plate, the workpiece W is installed on the rollers 172, 174, and 176. When the workpiece W is a flexible sheet, the workpiece W is wound on the rollers 172, 174, and 176. Thereby, since the workpiece | work W does not contact the upper electrode structure 108 and the lower electrode structure 118, damage to the workpiece | work W is suppressed. In addition, since plasma acts on both surfaces of the workpiece W simultaneously, both surfaces of the workpiece W are simultaneously subjected to plasma treatment, and in the case of the workpiece W in which the through holes are formed, the plasma also acts on the inner wall surface of the through holes. The inner wall surface of the through hole is also plasma treated.

  The rollers 172, 174, and 176 are made of a conductor and are grounded by a ground wire 178. Thereby, the workpiece | work W which contact | connects the cylindrical surface of roller 172,174,176 is also earth | grounded. It is not essential that the rollers 172, 174, and 176 are entirely made of a conductor, and it is sufficient if the grounded conductor is exposed on the cylindrical surface with which the workpiece W is in contact. Since the rollers 172, 174, and 176 are installed outside the plasma region 1902, even if a grounded conductor is exposed on the cylindrical surface, it does not cause arc discharge. Further, it is not essential to ground all of the rollers 172, 174, and 176, and it is sufficient to ground a part of them.

  The rollers 172, 174, and 176 rotate around the rotation axis. A drive mechanism for rotating the rollers 172, 174, 176 is connected to all or a part of the rotation shafts of the rollers 172, 174, 176. Thereby, the workpiece | work W which contact | connects a cylindrical surface is conveyed with the state earth | grounded.

  A conveyance grounding mechanism that does not use the rollers 172, 174, and 176 may be adopted. However, if the conveyance grounding mechanism 134 that uses the rollers 172, 174, and 176 is configured, the workpiece W is conveyed and grounded with a simple configuration. .

{Pulse power supply 124}
(A) Power supply type;
The pulse power supply 124 may be any device that outputs an electric pulse capable of generating a streamer discharge without generating an arc discharge between the first output end 126 and the second output end 128. May be used, but it must be an inductive energy storage (IES) power source (hereinafter referred to as "IES power source") that releases energy stored in the form of a magnetic field in the inductive element in a short time. Is desirable. This is because the IES power supply is compared with a capacitive energy storage (CES) power supply (hereinafter referred to as “CES power supply”) that discharges energy stored in the form of an electric field in the capacitive element in a short time. This is because remarkably large energy can be input at high repetition. Typically, when the electrode structure is the same, when an IES power supply is employed, the energy per pulse used for the reaction for generating plasma (hereinafter referred to as “one pulse energy”) is a CES power supply. Approximately one order of magnitude larger than the case. This difference between the IES power supply and the CES power supply is caused by the fact that the electric pulse generated by the IES power supply has a rapid increase in voltage, whereas the electric pulse generated by the CES power supply has a slow increase in voltage. That is, when the IES power source is adopted, the discharge starts after the voltage has sufficiently increased, and one pulse energy can be sufficiently increased, whereas when the CES power source is employed, the voltage does not sufficiently increase. Discharge starts and occurs because the energy of one pulse cannot be increased sufficiently.

  5 to 7 show an electric pulse (hereinafter referred to as “nanopulse”) having a pulse width generated by the IES power supply in the order of nanoseconds and an electric pulse having a pulse width generated by the CES power supply in the order of microseconds (hereinafter referred to as “nanopulse”). FIG. 3 is a diagram showing a schematic waveform of “micropulse”. 5A and 5B are voltage waveforms of nanopulses generated by the IES power supply and micropulses generated by the CES power supply, respectively, and FIGS. 6A and 6B are IES power supply, respectively. 7A and FIG. 7B show the voltage and current of the nanopulse generated by the IES power supply and the micropulse generated by the CES power supply, respectively. It is a figure which shows the waveform of the product of.

  One pulse energy is calculated by integrating the product of the voltage and current shown in FIGS. 7A and 7B with time. As shown in FIG. 5 and FIG. 6, the current flows in the positive direction almost synchronously with the voltage increase, and flows in the negative direction almost synchronously with the voltage decrease. 7B is proportional to the area obtained by subtracting the area of the region B in which the waveform is negative from the area of the region A in which the waveform is positive in FIG.

(B) a switching element;
As the IES power supply, it is desirable to employ a power supply using an electrostatic induction thyristor (hereinafter referred to as “SI thyristor”) as a switching element for controlling the supply of current to the inductive element. This is because by using the SI thyristor as a switching element, an electrical pulse having a fast rise can be generated, and thus the above-described streamer discharge can be easily generated. The use of the SI thyristor as a switching element can generate an electrical pulse that rises quickly, because the SI thyristor is not insulated from the gate and can quickly extract carriers from the gate, so it turns off at high speed. Because it can. For details on the operating principle of the IES power supply, see, for example, Katsuji Iida, Ken Sakuma: “Ultra-short pulse generation circuit using an SI thyristor (IES circuit)”, SI Device Symposium Proceedings, Vol. 15, Page. 40-45 (issued on June 14, 2002).

(C) a circuit diagram of an IES power supply 180 using the SI thyristor 358 as a switching element;
FIG. 8 is a circuit diagram of an IES power supply 180 using an SI thyristor 188 that can be suitably used for the pulse power supply 124 as a switching element. Of course, the circuit diagram shown in FIG. 8 is merely an example, and various modifications can be made.

  As shown in FIG. 8, the IES power supply 180 includes a DC power supply 182 that supplies electrical energy and a capacitor 184 that enhances the discharge capability of the DC power supply 182.

The voltage of the DC power supply 182 is allowed to be significantly lower than the peak voltage of the electric pulse generated by the IES power supply 180. For example, even if the peak voltage of the primary side voltage V ₁ generated on the primary side of the step-up transformer 186 described later reaches 4 kV, the voltage of the DC power source 182 may be several tens to several hundreds volts. The lower limit of this voltage is determined by the latching voltage of the SI thyristor 188 described later. Since the IES power supply 180 can use such a low-voltage DC power supply 182 as an electrical energy source, it can be constructed in a small size and at a low cost.

  Capacitor 184 is connected in parallel with DC power supply 182. Capacitor 184 enhances the discharge capability of DC power supply 182 by apparently reducing the impedance of DC power supply 182.

  The IES power supply 180 further includes a step-up transformer 186, an SI thyristor 188, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 190, a gate drive circuit 192, and a diode 194.

  In the IES power supply 180, the DC power supply 182, the primary side of the step-up transformer 186, the anode (A) / cathode (K) of the SI thyristor 188, and the drain (D) / source (S) of the MOSFET 190 are connected in series. Connected. In other words, one end on the primary side of the step-up transformer 186 is the positive electrode of the DC power supply 182, the other end on the primary side of the step-up transformer 186 is the anode of the SI thyristor 188, and the cathode (K) of the SI thyristor 188 is the drain ( D), the source (S) of the MOSFET 190 is connected to the negative electrode of the DC power source 182. As a result, a current can be supplied from the DC power source 182 to these circuit elements. In the IES power supply 180, the gate (G) of the SI thyristor 188 is connected in parallel with one end on the primary side of the step-up transformer 186 via the diode 194. That is, the gate (G) of the SI thyristor 188 is connected to the anode (A) of the diode 194, and the cathode (K) of the diode 194 is connected to one end on the primary side of the step-up transformer 186 (positive electrode of the DC power supply 182). A gate drive circuit 192 is connected between the gate (G) and source (S) of the FET.

  The step-up transformer 186 further boosts the electric pulse given to the primary side and outputs it to the secondary side. One end of the step-up transformer 186 on the secondary side is the first output end 126 and the other end is the second output end 128.

  The SI thyristor 188 can be turned on and off in response to a signal applied to the gate (G).

  The MOSFET 190 is a switching element in which the conduction state between the drain (D) and the source (S) changes in response to a signal given from the gate drive circuit 192. The on-voltage or on-resistance of MOSFET 190 is desirably low. Further, the withstand voltage of MOSFET 190 needs to be higher than the voltage of DC power supply 182.

  The diode 194 blocks the current that flows when a positive bias is applied to the gate (G) of the SI thyristor 188, that is, when the positive bias is applied to the gate (G) of the SI thyristor 188, It is provided to prevent driving.

(D) Outline of operation of IES power supply 180 using SI thyristor 188 as a switching element;
When an electrical pulse is generated in the IES power supply 180, first, an ON signal is given from the gate driving circuit 192 to the gate of the MOSFET 190, and the drain (D) and source (S) of the MOSFET 190 are brought into a conducting state. Then, since the SI thyristor 188 is a normally-on type switching element and the anode (A) and the cathode (K) of the SI thyristor 188 are in a conductive state, a current flows to the primary side of the step-up transformer 186. In this state, since a positive bias is applied to the gate (G) of the SI thyristor 188, the conduction state between the anode (A) and the cathode (K) of the SI thyristor 188 is maintained.

  Subsequently, the application of the ON signal from the gate drive circuit 192 to the MOSFET 190 is stopped, and the drain (D) and the source (S) of the MOSFET 190 are made non-conductive. Then, carriers are discharged from the gate (G) of the SI thyristor 188 at high speed by current driving, and the anode (A) and cathode (K) of the SI thyristor 188 are in a non-conducting state. Current flow is stopped at high speed. As a result, an induced electromotive force is generated on the primary side of the step-up transformer 186, and a high voltage is also generated on the secondary side of the step-up transformer 186.

{Experiment}
Table 1 is a list showing the results of plasma processing of a workpiece under three different conditions 1 to 3. “Work material” in Table 1 indicates whether the material of the work is PET (polyethylene terephthalate) or SUS (stainless steel). “Floating power supply acceptance / rejection” indicates whether or not the above-described floating power supply is adopted. Note that, under conditions 1 and 2 in which the floating power feeding is not employed, the lower electrode side is grounded. “Pre-treatment contact angle” represents the water contact angle of the surface of the workpiece before the plasma treatment, and “Post-treatment contact angle” represents the water contact angle of the surface of the workpiece after the plasma treatment. The average value and variation of the “post-treatment contact angle” were obtained from five measurement points A, B, C, D, and E of a workpiece having a width of 300 mm shown in FIG. The variation is the difference between the maximum value and the minimum value of the water contact angle.

  In addition, in conditions 1-3, the experimental conditions shown in Table 2 are common.

  As is clear from Table 1, when the workpiece is PET, the contact angle on both sides of the workpiece is sufficiently reduced even if the workpiece is not floating power feeding. However, when the workpiece is SUS, the workpiece is not floating feeding power. In this case, discharge occurs locally only on the upper surface of the workpiece, and the contact angle does not decrease sufficiently. On the other hand, in the case of floating power feeding, the contact angle is sufficiently lowered as in the case of PET.

{Others}
Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited to the above description. Innumerable variations not illustrated may be envisaged without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 102 Plasma processing apparatus 104 Upper electrode 106 Upper dielectric barrier 114 Lower electrode 116 Lower dielectric barrier 124 Pulse power supply 130 1st wiring 132 2nd wiring 192 Plasma area | region

Claims (5)

A plasma processing apparatus for plasma processing a conductor work,
A first electrode isolated from ground;
A second electrode isolated from ground;
A floating power source in which a first output terminal and a second output terminal are insulated from a ground, and an electric pulse is output between the first output terminal and the second output terminal;
A first wiring that is insulated from the ground and connects the first output terminal and the first electrode;
A second wiring that is insulated from the ground and connects the second output terminal and the second electrode;
Provided outside a plasma region in which plasma is generated by application of an electric pulse from the floating power source to the first electrode and the second electrode, and separated from the first electrode and the second electrode. A grounding mechanism for passing the plasma region through the conductor work piece and grounding the conductor work piece,
A plasma processing apparatus comprising: The transport ground mechanism is
A roller in which a grounded conductor is exposed on a cylindrical surface and rotates around a rotation axis;
A plasma processing apparatus according to claim 1.   3. The plasma processing apparatus according to claim 1, wherein the first electrode and the second electrode are conductor plates perpendicular to a conveying direction of the conductor workpiece.   3. The plasma processing apparatus according to claim 1, wherein the first electrode and the second electrode are a conductor rod or a conductor pipe perpendicular to a conveying direction of the conductor workpiece. A first dielectric barrier covering the first electrode;
A second dielectric barrier covering the second electrode;
Further comprising
The transport ground mechanism is
The plasma processing apparatus according to any one of claims 1 to 4, wherein the plasma region is passed through a conductor work in a state of being separated from the first dielectric barrier and the second dielectric barrier.

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