JP2007250426A - Electrode structure of plasma processing system and plasma processing system provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode structure for a plasma processing system for surely suppressing arc discharge, and also to provide a plasma processing system provided with the same. <P>SOLUTION: The upper electrode member 10a and a lower electrode member 10b facing together in the plasma processing system respectively include: an electrode body 11 comprising a metal plate; an insulation case 12 containing the electrode body 11; an insulation lid 13 for closing the insulation case 12; a ground electrode covering insulation member 14; and a ground electrode metal bar. A space containing the insulation body 11 is filled with a predetermined fill gas having a higher discharge starting voltage than a diluent gas contained in a process gas for carrying out the plasma process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrode structure of a plasma processing apparatus and a plasma processing apparatus including the same, and in particular, an electrode structure of a plasma processing apparatus that performs predetermined plasma processing on a substrate to be processed by plasma generated under atmospheric pressure; The present invention relates to a plasma processing apparatus having such an electrode structure.

  There is a mode in which a plasma processing apparatus generates plasma under atmospheric pressure, and such a plasma processing apparatus is called an atmospheric pressure plasma processing apparatus. The atmospheric pressure plasma processing apparatus disclosed in Patent Document 1 will be described as an example of such an atmospheric pressure plasma processing apparatus. In this atmospheric pressure plasma processing apparatus, a pair of electrode portions are arranged so as to face each other with a gap in the vertical direction. Each of the pair of electrode portions has an electrode body made of metal or alloy. By applying a high-frequency electric field between the pair of electrode portions, a predetermined processing gas introduced into a region between the electrode portions is turned into plasma. By exposing the substrate to be processed to the plasma, the surface of the substrate to be processed is subjected to plasma processing.

  In the electrode structure of this plasma processing apparatus, if the metal or alloy of the electrode body is exposed on the surfaces of the electrode portions on the opposite sides of the pair of electrode portions, concentration of the applied electric field is likely to occur. There is a risk of arc discharge between the electrode portions. For this reason, by disposing a solid dielectric so as to cover the surfaces of the electrode bodies facing each other, arc discharge is prevented, damage to the electrode portion is prevented, and stable glow discharge is obtained. .

  However, in the electrode structure of the plasma processing apparatus disclosed in Patent Document 1, arc discharge occurs in each of the pair of electrode portions even though arc discharge can be prevented between the pair of electrode portions. There is a fear. That is, when a gap is generated due to a manufacturing error or the like between the solid dielectric and the electrode body made of metal or the like, arc discharge may occur in the gap. In particular, when a plasma treatment is performed using a gas such as helium having a low discharge start voltage as a dilution gas for diluting the additive gas contained in the treatment gas, such a dilution gas may be generated between the electrode body and the solid dielectric. When entering the gap, it is easy to reach arc discharge.

In order to eliminate such arc discharge, Patent Document 2 proposes an electrode structure of a plasma processing apparatus that prevents a gap from being formed between the solid dielectric and the electrode body. In the electrode structure of the plasma processing apparatus, plate-like support members that support the end portions on both sides of the solid dielectric are disposed on both sides of the electrode body. The plate-like support member that supports the solid dielectric is slid, and the plate-like support member is fixed to the electrode body in a state where the solid dielectric is pressed against the electrode body. In this way, a gap is prevented from being formed between the solid dielectric and the electrode main body, thereby suppressing the occurrence of arc discharge.
Japanese Patent Laid-Open No. 2-15171 JP 2005-15841 A

  However, the electrode structure of the conventional plasma processing apparatus has the following problems. In order to prevent a gap between the solid dielectric and the electrode body by pressing the solid dielectric against the electrode body, the surfaces of the electrode body and the solid dielectric that are in contact with each other are smooth. It is assumed that there is no warping. By the way, in recent years, the size of the substrate to be processed has been increased, and in the plasma processing apparatus, in order to process such a large substrate to be processed, an electrode portion whose length in the longitudinal direction exceeds, for example, 1 m as an electrode portion. Is needed.

  In the electrode main body and solid dielectric of such an electrode part, it becomes difficult to make the surface uniformly smooth over the longitudinal direction. In addition, since the electrode portion becomes long, the electrode main body and the solid dielectric are easily bent or warped. As a result, even when the solid dielectric is pressed against the electrode body, a gap may be partially formed between the electrode body and the solid dielectric, and arc discharge occurs in the gap.

  In the pair of electrode portions, the electrode main body and the solid dielectric are expanded by heat generated by the plasma generated between the pair of electrode portions. At this time, since the coefficient of thermal expansion (dimensional change rate per unit temperature change) is different between the electrode body made of metal and the solid dielectric, even if there is no gap between the electrode body and the solid dielectric, There may be a gap between the expanding electrode body and the solid dielectric. As a result, there is a problem that arc discharge occurs in the generated gap.

  The present invention has been made to solve the above problems, and one object is to provide an electrode structure of a plasma processing apparatus that reliably suppresses arc discharge, and the other object is to provide such an electrode structure. A plasma processing apparatus having an electrode structure is provided.

  The electrode structure of the plasma processing apparatus according to the present invention performs a predetermined plasma treatment introduced into a region between the pair of electrode portions by applying a predetermined voltage between the pair of electrode portions facing each other. Plasma processing for applying plasma processing to a member to be processed by converting the processing gas including an additive gas to be applied and a dilution gas for diluting the additive gas into plasma and exposing the member to be processed to the generated plasma atmosphere It is an electrode structure of an apparatus. Each of the pair of electrode portions includes an electrode main body, a covering member, and a filling gas introducing portion. The electrode body is made of metal and applied with a voltage. The covering member is formed of a fixed dielectric and has a space for accommodating the electrode body, and the electrode body is disposed in the space so as to surround the electrode body. The filling gas introduction unit fills the space of the covering member in which the electrode main body is accommodated with a predetermined gas having a higher discharge start voltage than the dilution gas.

  According to this configuration, by using a gas having a higher discharge start voltage than the dilution gas as the filling gas in the space of the covering member that houses the electrode body formed of metal, an arc is generated between the electrode body and the covering member. It is possible to prevent discharge from occurring.

  In order to reliably supply such a filling gas to each of the electrode parts, it is preferable to include a filling gas supply part that sends the filling gas to the filling gas introduction part.

  Moreover, it is preferable that the pressure in the space of the covering member filled with the filling gas is set higher than the pressure outside the covering member.

  In this case, it is possible to prevent the dilution gas that is easily discharged from flowing into the space from the covering member, and thus the dilution gas flows into the space in which the electrode body is accommodated. Abnormal discharge and arc discharge which occur with it can be suppressed reliably.

  As a specific structure of the covering member, it is preferable that the covering member includes a case member having a concave portion that accommodates the electrode main body, and a lid member that closes the concave portion while accommodating the electrode main body.

  In this case, the covering member more preferably includes a seal member interposed between the case member and the lid member.

Thereby, the space in which the electrode main body is accommodated can be reliably sealed.
The specific filling gas is selected from the group consisting of nitrogen (N ₂ ), oxygen (O ₂ ), Freon, carbon tetrafluoride (CF ₄ ), carbon dioxide (CO ₂ ), and sulfur hexafluoride (SF ₆ ). It is preferable to use at least one of the gases described above.

In addition, it is preferable to use at least one gas selected from the group consisting of helium (He), argon (Ar), neon (Ne), xenon (Xe), and nitrogen (N ₂ ) as the dilution gas.

As these filling gas and dilution gas, an appropriate gas is selected according to the plasma processing.
In particular, it is preferable that the same type of gas as the additive gas is used as the filling gas.

  As a result, even if the filling gas flows out into the plasma atmosphere generated between the pair of electrodes and reacts / decomposes, the reaction / decomposition is the same as the reaction / decomposition of the additive gas. Unexpected plasma processing is not performed on the processing substrate.

  A plasma processing apparatus according to the present invention is for applying a predetermined plasma treatment introduced into a region between a pair of electrode portions by applying a predetermined voltage between the pair of electrode portions facing each other. Plasma having an electrode structure for performing plasma processing on a member to be processed by converting the processing gas containing the additive gas and a dilution gas for diluting the additive gas into plasma and exposing the member to be processed to the generated plasma atmosphere It is a processing device. Each of the pair of electrode portions includes an electrode main body, a covering member, and a filling gas introducing portion. The electrode body is made of metal and applied with a voltage. The covering member is formed of a fixed dielectric and has a space for accommodating the electrode body, and the electrode body is disposed in the space so as to surround the electrode body. The filling gas introduction unit fills the space of the covering member in which the electrode main body is accommodated with a predetermined gas having a higher discharge start voltage than the dilution gas.

  According to this plasma processing apparatus, by using a gas having a discharge start voltage higher than the dilution gas as the filling gas in the space of the covering member that houses the electrode body formed of metal, the space between the electrode body and the covering member is used. It is possible to prevent arc discharge from occurring in

  An electrode structure of a plasma processing apparatus according to an embodiment of the present invention will be described. First, as shown in FIG. 1, in the plasma processing apparatus 1, a pair of electrode portions 10, 10 a, and 10 b are disposed at a predetermined interval in the vertical direction. Moreover, the conveyance part 81 which conveys the to-be-processed substrates 80, such as a glass substrate, in a predetermined direction is provided. The substrate to be processed 80 transported by the transport unit 81 is exposed to the plasma atmosphere generated in the region while passing through the region sandwiched between the pair of electrode portions 10a and 10b, thereby performing a predetermined plasma process. Will be given.

  The structure of the electrode unit 10 will be described in more detail. As shown in FIGS. 2 and 3, the pair of electrode units 10 includes an upper electrode unit 10 a positioned above the substrate to be processed 80 to be transported, and a lower electrode unit 10 b positioned below the substrate to be processed 80. It is prepared for. The upper electrode portion 10a and the lower electrode portion 10b are maintained at a constant distance by interposing spacers 50 at both ends in the longitudinal direction of the electrode portion 10.

  Each of the upper electrode portion 10a and the lower electrode portion 10b includes an electrode body 11 made of a plate metal, a dielectric case 12 that houses the electrode body 11, a dielectric lid 13 that closes the dielectric case 12, and a ground electrode-covered dielectric. 14 and a ground electrode metal rod (not shown). The electrode body 11 is made of a metal such as aluminum, stainless steel, or copper. In order to prevent the concentration of the electric field generated by the power supplied to the electrode body 11, the ridge portion of the electrode body 11 is rounded. Moreover, it is preferable to attach a ceramic sprayed film (not shown) such as alumina on the four surfaces positioned in the longitudinal direction of the electrode body 11 in order to reduce electric field concentration. The electrode main body 11 is provided with a circular water-cooled tube hole 31 so as to penetrate the plate metal along the longitudinal direction. By flowing the cooling water 30 through the water cooling tube hole 31, the electrode unit 10 is cooled.

  The dielectric case 12 is made of ceramic such as alumina or zirconia. Further, it may be formed of an insulating resin such as Teflon (registered trademark) or PEEK (registered trademark). Thereby, the surface of the electrode body 11 of the upper electrode portion 10a facing the lower electrode portion 10b is covered with the solid dielectric, and the plasma A generated in the region between the pair of electrode portions 10 is covered. Prevents arc discharge. The cross-sectional shape along the direction substantially orthogonal to the longitudinal direction of the dielectric case 12 is a concave shape, and the electrode body 11 is accommodated inside the concave shape (concave portion). In a state where the electrode body 11 is housed inside the recess of the dielectric case 12, a dielectric lid 13 is mounted so as to cover the electrode body 11, and the space (inside the recess) housing the electrode body 11 is sealed. Will be.

  As shown in FIG. 4, a bolt hole 16 through which the dielectric bolt 15 is passed is provided on the side surface of the dielectric case 12, and a screw hole 17 is formed in the dielectric lid 13. By inserting the dielectric bolt 15 through the bolt hole 16 and fastening it with the screw hole 17, the dielectric lid 13 is fixed to the dielectric case 12, and the electrode body 11 is covered by the dielectric case 12 and the dielectric lid 13. It will be. The electrode body 11, the dielectric case 12, and the dielectric lid 13 of the electrode unit 10 may be collectively referred to as a hot electrode here for convenience.

As shown in FIG. 3, a filling gas supply unit 21 for filling a predetermined filling gas in a space (inside the recess) in which the electrode body 11 is housed is provided. As this filling gas, a gas having a discharge start voltage higher than that of a dilution gas, which will be described later, is used as an arc, so that an arc is formed between the electrode body 11 and the dielectric case 12 or between the electrode body 11 and the dielectric lid 13. Plays a role in preventing discharge. As such a filling gas, for example, nitrogen (N ₂ ), oxygen (O ₂ ), Freon, (CF ₄ ), carbon dioxide (CO ₂ ), sulfur hexafluoride (SF ₆ ), and the like can be used.

  Further, as the filling gas 20, it is preferable to use the same type of gas as the additive gas in the processing gas. This is due to the following reason. That is, when a gas different from the additive gas is used as the filling gas 20, for example, the filling gas 20 flows out from the contact portion (gap) between the dielectric case 12 and the dielectric lid 13 to the seed slit 18 side. If this is not the case, the filling gas 20 is mixed into the processing gas, and the filling gas is sent into the atmosphere of the plasma A. For this reason, the filling gas 20 is reacted and decomposed by the plasma, and an undesired plasma process is performed on the substrate 80 to be processed, and there is a possibility that a predetermined plasma process that should be originally performed cannot be performed.

  On the other hand, when the same kind of gas as the additive gas is used as the filling gas 20, even if the filling gas 20 is sent to the plasma A and reacted / decomposed, the reaction / decomposition of the additive gas does not occur. This is the same as reaction / decomposition, and the substrate to be processed is not subjected to unexpected plasma processing.

  The filling gas supply unit 21 that supplies such a filling gas to the electrode unit 10 includes a supply source 26 such as a cylinder that supplies the filling gas 20, a regulator 27, and a flow rate adjustment controller 28. The regulator 27 is connected to the supply source 26 by piping to reduce the pressure of the filling gas supplied from the supply source 26, and the flow rate adjustment controller 28 connected to the regulator 27 adjusts the flow rate of the reduced filling gas. . On the other hand, the electrode unit 10 is provided with a filling gas supply connector 25 for taking in the supplied filling gas. The filling gas supply connector 25 and the filling gas supply unit 21 are connected by a flexible pipe formed of, for example, PFA or the like.

  The filling gas supply connector 25 is provided on one utility supply member 40 side of the utility supply member 40 disposed at both ends of the electrode portion 10 in the longitudinal direction. The utility supply member 40 is made of Teflon (registered trademark), and a thread for attaching the filling gas supply connector 25 is formed at a predetermined position in the utility supply member 40.

  Moreover, the utility supply member 40 is formed with a through-hole for guiding cooling water to the water-cooled tube hole, and a hole for allowing a predetermined metal bolt to pass therethrough. By attaching the metal bolt, the electrode body 11 and the high voltage cable are electrically connected. Furthermore, the opposing surfaces of the utility supply member 40 and the dielectric case 12 are in close contact with each other, and the opposing surfaces of the utility supply member 40 and the dielectric lid 13 are in close contact with each other to house the electrode body 11. The filling gas can be prevented from flowing out of the space.

  Further, a filling gas discharge unit 24 for discharging the filling gas filled in the space in which the electrode body 11 is housed is provided. The filling gas discharge unit 24 is connected to the other utility supply member 40 opposite to the utility supply member 40 to which the filling gas supply connector 25 is attached via a pipe. When a harmless gas is used as the filling gas, the filling gas discharge unit 24 releases it to the atmosphere as it is. When a harmful gas is used, the filling gas discharge unit 24 performs exhaust gas treatment to remove harmful substances, and then releases the atmosphere. Release into.

  Each electrode body 11 of the upper electrode portion 10a and the lower electrode portion 10b is provided with a power input portion (not shown) for supplying power to one end portion in the longitudinal direction. One end side of the high voltage cable is connected to the power input unit via a metal bolt, and the other end side of the high voltage cable is connected to a high frequency high voltage power source (not shown).

  In the high-frequency high-voltage power supply, the three-phase voltage of 200 V from the commercial AC power supply is boosted to 1 to 30 kV by the transformer, and the two powers (AC waves) with a frequency of 1 to 50 kHz are output so that they are in opposite phases Is done. The output electric power is supplied to each of the upper electrode portion 10a and the lower electrode portion 10b through a high voltage cable. The supplied electric power generates a high electric field between the upper electrode portion 10a and the lower electrode portion 10b, and plasma is efficiently generated.

  The ground electrode covering dielectric 14 is made of ceramic such as alumina or zirconia. Two ground electrode-covered dielectrics 14 are prepared for one hot electrode, and the ground electrode-covered dielectric 14 has a distance of about 0.5 mm to 2 mm between the longitudinal side surfaces of the hot electrode facing each other. Attached apart. A ground electrode metal bar (not shown) is provided on the surface of the ground electrode covered dielectric 14 opposite to the side facing the hot electrode, and this ground electrode metal bar is connected to the ground potential.

  In this way, a predetermined gas for performing plasma treatment is introduced into the gap provided between the ground electrode covering dielectric 14 and the hot electrode. This gap is referred to as a seed slit 18. The predetermined gas includes an additive gas that substantially performs plasma processing and a diluent gas that dilutes the additive gas. The combined dilution gas and additive gas may be referred to as a processing gas.

As a diluent gas, nitrogen or the like is used in addition to a rare gas such as helium (He), argon (Ar), neon (Ne), and xenon (Xe). The additive gas depends on the plasma processing to be performed on the substrate to be processed 80, but in the case of etching or ashing, a gas such as oxygen (O ₂ ), nitrogen (N ₂ ), hydrogen (H ₂ ), Air, etc. Alternatively, a fluorine compound gas such as CF ₄ is used.

  The processing gas is filled in a cylinder (not shown) of the processing gas supply unit 45. The processing gas filled in the cylinder is depressurized, and the flow rate is adjusted and supplied to the electrode unit 10. The electrode unit 10 is provided with a processing gas reservoir 70 that temporarily stores the supplied processing gas. A diffusion plate built-in shower plate 60 for diffusing the processing gas is disposed between the processing gas reservoir 70 and the dielectric lid 13. The electrode part and its peripheral part of the plasma processing apparatus are configured as described above.

  Next, as the flow of each gas in the plasma processing apparatus described above, first, the flow of the processing gas will be described. As shown in FIGS. 2 to 5, the processing gas filled in the processing gas cylinder is decompressed to a predetermined pressure, adjusted to a predetermined flow rate, and supplied to the electrode unit 10. The processing gas supplied to the electrode unit 10 is once sent to the processing gas reservoir 70. The processing gas stored in the processing gas reservoir 70 is uniformly diffused in the longitudinal direction of the electrode portion 10 by passing through the diffusion plate built-in shower plate 60 and flows into the seed slit 18.

  The processing gas that has flowed into the seed slit 18 of the upper electrode portion 10a flows downward through the seed slit 18 where the lower electrode portion 10b is located, and is generated in a space between the upper electrode portion 10a and the lower electrode portion 10b. It is ejected toward the atmosphere (region) of the plasma A. On the other hand, the processing gas that has flowed into the seed slit 18 of the lower electrode portion 10b flows upward through the seed slit 18 where the upper electrode portion 10a is located, and is ejected toward the atmosphere of plasma A.

  In addition, when electric power is supplied to the electrode unit 10, an electric field is generated in the seed slit 18 between the ground electrode-covered dielectric 14 and the hot electrode, and the processing gas passing through the seed slit 18 is also plasma. Will be converted. By the seed plasma B generated in the seed slit 18, the discharge start voltage of the plasma A generated in the space between the upper electrode portion 10a and the lower electrode portion 10b is lowered, and stable discharge can be maintained. Further, the processing gas is decomposed and reacted also by the seed plasma B generated in the seed slit 18, thereby increasing the ratio (usage efficiency) of the processing gas contributing to the plasma processing. As a result, the processing capability of the plasma processing apparatus can be improved.

  Next, the flow of the filling gas will be described. The filling gas filled in the filling gas cylinder 26 is decompressed to a predetermined pressure, adjusted to a predetermined flow rate, and supplied to the electrode unit 10. The filling gas supplied to the electrode unit 10 flows through the supply connector 25, through the through hole provided in the utility supply member 40 and the supply slit 22, and into the space in which the electrode body 11 is accommodated.

  The supply slit 22 is formed along a direction (short side direction) orthogonal to the longitudinal direction of the electrode portion 10 in the utility supply member 40 as a gap having a predetermined interval extending in a substantially horizontal direction. It plays a function of jetting uniformly in the direction. As shown in FIG. 5, the utility supply member 40 is provided with a protruding portion 41 for attaching the utility supply member 40 to the electrode portion 10.

  On the other hand, the electrode portion 10 is formed with an insertion port into which the protruding portion 41 is inserted by the dielectric case 12, the dielectric lid 13 and the electrode body 11. A gap X <b> 1 is provided around the protrusion 41 by forming a portion having a cross-sectional area smaller than the cross-sectional area of the insertion opening in the protrusion 41. Thereby, the filling gas 20 ejected from the supply slit 22 does not flow only into the dielectric lid 13 side of the protrusion 41 but passes through the gap X1 to the side surface portion and the bottom surface portion inside the dielectric case 12. Will also flow.

  At this time, as shown in FIG. 4, the electrode body 11, the dielectric case 12 and the dielectric lid 13 that form a space in which the electrode body 11 is accommodated, There is a place where a gap X occurs in a portion where the dielectric case 12 contacts each other and a portion where the electrode body 11 and the dielectric lid 12 contact each other. In addition, there is a place where the gap X is generated due to warping or bending caused by the difference in coefficient of thermal expansion between the electrode body 11 and the dielectric case 12 or the like. The filling gas ejected from the supply slit 22 also diffuses into such a gap X, and the gap X is filled with the filling gas.

  The filling gas also diffuses into the gap Y existing at the portion where the surface of the dielectric bolt 15 that fastens the dielectric case 12 and the dielectric lid 13 is in contact, and the dielectric case 12 and the dielectric lid 13 It diffuses also into the space | gap Z which exists in the part which mutually contacts, and these space | gap Y and Z are each filled with filling gas. A part of the filling gas filled in the gaps Y and Z flows into the seed slit 18. In FIG. 4, the voids are intentionally enlarged so that it can be seen that such voids X, Y, and Z exist.

  As shown in FIG. 3, most of the filled gas 20 flows in the longitudinal direction in the space in which the electrode body 11 is housed, and the piping is routed from the discharge slit 23 provided on the side opposite to the supply slit 22. Then, it is sent to the filling gas discharge unit 24. The filling gas sent to the filling gas discharge unit 24 is released into the atmosphere as it is, or when a harmful substance is contained, it is released into the atmosphere after removing the harmful substance.

  Since the filling gas discharge unit 24 is not provided with a mechanism for positively sucking the filling gas 20, the pressure in the space containing the electrode body 11 filled with the filling gas 20 is the pressure outside the space. Will be held higher.

  Thus, by maintaining the inside of the space in which the electrode body 11 is housed at a pressure higher than the pressure outside the space, a dilute gas that is likely to be discharged is discharged from, for example, the gap between the dielectric case 12 and the dielectric lid 13. It can be prevented from flowing in. Thereby, the abnormal discharge and arc discharge which generate | occur | produce with such dilution gas flowing into the space where an electrode main body is accommodated can be suppressed reliably.

  As described above, the processing gas is sent into the plasma generated in the region between the upper electrode portion 10a and the lower electrode portion 10b, and the substrate to be processed is exposed to the plasma atmosphere while being transferred by the transfer portion 81. Thus, predetermined plasma treatments such as ashing, etching, hydrophilization, water repellency, and film formation are sequentially performed on the surface of the substrate to be processed. The to-be-processed substrate 80 that has been subjected to the plasma processing is unloaded from the plasma processing apparatus by the transfer unit 81.

Modification Part of the filling gas 20 filled in the space containing the electrode body 11 is also diffused into the gap Y and the gap Z (see FIG. 4) while diffusing the electrode portion 10 in the longitudinal direction. May flow out into the seed slit 18 through which it passes. Therefore, as described above, the filling gas 20 is preferably the same type of gas as the additive gas included in the processing gas in relation to the processing gas for performing a predetermined plasma process on the substrate to be processed.

  However, even in the case of a filling gas composed of the same type of gas as the additive gas, in the plasma processing in which process conditions are strictly required, the process conditions may change due to such filling gas flowing into the seed slit. is there. Therefore, as a modification, an electrode structure of a plasma processing apparatus that does not allow the filling gas to flow into the seed slit will be described.

  In the electrode structure of the plasma processing apparatus according to the modification, a seal is provided between the dielectric case and the dielectric lid to prevent the filling gas from flowing out. As shown in FIG. 6, a bolt inserted through the dielectric lid 13 is fastened to the dielectric case 12 with a Viton (registered trademark) sheet 19 sandwiched between the dielectric case 12 and the dielectric lid 13. Has been. By fastening the bolt to the dielectric case 12, the sheet 19 sandwiched between the dielectric case 12 and the dielectric lid 13 is crushed, and the dielectric case 12 and the dielectric lid 13 are in contact with each other. Will be sealed. Thus, the filling gas filled in the space in which the electrode body 11 is accommodated by the sheet 19 is prevented from flowing out into the seed slit 18.

  Also, the direction of fastening the bolt is not fastened from the seed slit 18 side, but fastened from the top surface side of the dielectric lid 13, so that the filling gas 20 is seeded from the gap between the bolt 15 and the bolt hole 16. Outflow to the slit 18 can be reliably prevented. In this way, it is possible to prevent the inflow of gases other than the predetermined processing gas, and to reliably perform the plasma processing that strictly requires process conditions on the substrate to be processed.

  Using the plasma processing apparatus having the electrode structure shown in FIGS. 1 to 5, an ashing process is performed as a plasma process on the substrate to be processed under the conditions shown in FIG. Was done. In addition, whether or not arc discharge was generated inside the electrode part, the electrode part was disassembled after the treatment, and the appearance of the electrode body, the dielectric case, and the dielectric lid was visually observed. Furthermore, the processing capability of the plasma processing apparatus was examined.

  The evaluation result will be described. In the electrode structure of the plasma processing apparatus according to the invention example, the filling gas diffuses not only in the space for housing the electrode body but also in the gap Y or the gap Z, so that the space between the upper electrode portion 10a and the lower electrode portion 10b is increased. It was confirmed that no arc discharge occurred in the space surrounded by the dielectric case 12 and the dielectric lid 13 even when the applied voltage to be applied was increased to 20 kV.

  On the other hand, in the electrode structure of the plasma processing apparatus according to the comparative example, since no filling gas is used, when a voltage of 18 kV or higher is applied between the upper electrode portion 10a and the lower electrode portion 10b, arc discharge is likely to occur. I understood it.

  Moreover, when the electrode part was disassembled and the external appearance of the electrode body, dielectric case, and dielectric lid was observed, the gap between the corners of the electrode body and the gap between the electrode body and the dielectric case were observed. An internal discharge (arc discharge) occurred in the gap between the electrode body and the dielectric lid, and the surface of the dielectric of the dielectric case and the dielectric lid changed from white to yellow, and the phenomenon of discharge burn was observed. On the other hand, in the electrode structure of the plasma processing apparatus according to the invention example, by supplying a filling gas, discoloration of the surface of alumina is not recognized even when the electrode part is decomposed after the plasma processing, and internal discharge can be suppressed. Has been demonstrated.

  Next, the ashing processing capability when performing the ashing process in the plasma processing apparatus will be described. The ashing capacity was evaluated as follows. First, the substrate to be processed on which a resist pattern is formed is exposed to a plasma atmosphere while being transported in a predetermined direction, and after the plasma processing is completed, the substrate to be processed is transported in the opposite direction. The operation (reciprocation) of exposing the plasma atmosphere to the plasma atmosphere again was performed 50 times, and the substrate to be processed on which the resist pattern was formed was exposed to the plasma atmosphere 100 times in total. Thereafter, the thickness of the resist pattern left on the substrate to be processed was measured using a step meter to determine the resist ashing amount per plasma treatment. In addition, the applied voltage applied to an electrode part was 18 kV.

  The evaluation result will be described. As shown in FIG. 8, the ashing rate per plasma treatment is 2.73 nm (27.3 mm) in the electrode structure of the plasma treatment apparatus according to the invention example, whereas the plasma treatment apparatus according to the comparative example is Then, it was found to be 2.51 nm (25.1 Å) lower than that. This is because, in the plasma processing apparatus according to the invention example, the filling gas is used, and compared with the comparative example in which no filling gas is used, the internal discharge in the electrode portion is prevented, and the power corresponding thereto is effectively plasma. This is considered to be due to the generation of A.

  Next, using the plasma processing apparatus having the electrode structure shown in FIG. 6, whether or not arc discharge occurs in the electrode portion by performing water repellent treatment as a plasma treatment on the substrate to be processed under the conditions shown in FIG. 9. Evaluation was performed. In addition, whether or not arc discharge was generated inside the electrode part, the electrode part was disassembled after the treatment, and the appearance of the electrode body, the dielectric case, and the dielectric lid was visually observed. Furthermore, the processing capability of the plasma processing apparatus was examined.

  The evaluation result will be described. In the electrode structure of the plasma processing apparatus according to the invention example, the applied voltage applied between the upper electrode portion 10a and the lower electrode portion 10b is increased to 22 kV by diffusing the filling gas into the space for housing the electrode body. However, it was confirmed that no arc discharge occurred between the upper electrode portion 10a and the lower electrode portion 10b.

  On the other hand, in the electrode structure of the plasma processing apparatus according to the comparative example, since no filling gas is used, when a voltage of 20 kV or more is applied between the upper electrode portion 10a and the lower electrode portion 10b, arc discharge is likely to occur. I understood it. Also, when the electrodes were disassembled and the appearance of the electrode body, dielectric case and dielectric lid were observed, the surface of the alumina in the dielectric case and dielectric lid was changed from white to yellow by internal discharge. The phenomenon of electric discharge burn was observed.

  On the other hand, in the electrode structure of the plasma processing apparatus according to the invention example, by supplying a filling gas, discoloration of the surface of alumina is not recognized even when the electrode part is decomposed after the plasma processing, and internal discharge can be suppressed. Has been demonstrated.

  Next, the water-repellent treatment capability when performing the water-repellent treatment in the plasma processing apparatus will be described. The water repellent treatment ability was evaluated as follows. First, a substrate to be processed on which an organic film pattern was formed was prepared, and the substrate was subjected to plasma treatment by exposing it to a plasma atmosphere. Then, an ether solvent was dropped on the surface of the substrate to be processed, and the contact angle of the droplet was measured. In addition, the applied voltage applied to an electrode part was 20 kV.

  The evaluation result will be described. As shown in FIG. 10, in the plasma processing apparatus according to the comparative example, the contact angle is 55.3 °, whereas in the electrode structure of the plasma processing apparatus according to the invention example, the contact angle is obtained by using the filling gas. Was slightly higher than that of 55.7 °, indicating that the water-repellent effect was improved.

In the above two embodiments, helium (He) is used as the dilution gas and oxygen (O ₂ ) and nitrogen (as the additive gases) are used as the plasma treatment performed on the substrate under atmospheric pressure. and ashing using N _2), has been described as carbon tetrafluoride (CF ₄₎ and nitrogen and the water-repellent treatment with (N ₂₎ as an example, respectively. In the electrode structure of the plasma processing apparatus according to the present invention, the plasma processing is not limited to the ashing processing and the water repellent processing, and can be applied to plasma processing such as dry etching and film formation. In the case of dry etching, for example, CF ₄ or the like is applied as an additive gas, and in the case of film formation, for example, SiH ₄ or the like is applied as an additive gas, and a filling gas suitable for each processing is selected. By doing so, it is possible to suppress arc discharge and internal discharge and perform efficient processing.

  Further, the plasma processing by the electrode structure of the plasma processing apparatus described above is not limited to the atmospheric pressure, but can be performed under a reduced pressure.

  The embodiment disclosed this time is an example, and the present invention is not limited to this. The present invention is defined by the terms of the claims, rather than the scope described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is particularly effectively applied as an electrode structure of a plasma processing apparatus that generates plasma under atmospheric pressure to perform surface modification of a substrate to be processed, formation of a thin film, and processing.

It is a perspective view of the plasma processing apparatus provided with the electrode structure of the plasma processing apparatus which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view taken along a cross-sectional line II-II shown in FIG. 1 in the same embodiment. FIG. 3 is a cross-sectional view taken along a cross-sectional line III-III shown in FIG. 1 in the same embodiment. FIG. 3 is a partial enlarged cross-sectional view showing mutually facing portions of a pair of electrode portions shown in FIG. 2 in the same embodiment. FIG. 4 is a partially enlarged cross-sectional view showing one end portion in the longitudinal direction of the pair of electrode portions shown in FIG. 3 in the same embodiment. In the same embodiment, it is the elements on larger scale of the electrode structure of the plasma processing apparatus which concerns on a modification. It is a figure which shows the ashing process conditions which concern on Example 1. FIG. It is a figure which shows the evaluation result of an ashing rate in the Example. It is a figure which shows the water-repellent treatment conditions which concern on Example 2. FIG. In the same Example, it is a figure which shows the evaluation result of water-repellent treatment capability.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus, 10 Electrode part, 10a Upper electrode part, 10b Lower electrode part, 11 Electrode body, 12 Dielectric case, 13 Dielectric cover, 14 Ground electrode covering dielectric material, 15 Dielectric bolt, 16 volt hole, 17 Screw hole, 18 kinds of slits, 19 sheets, 20 Filling gas, 21 Filling gas supply part, 22 Supply slit, 23 Exhaust slit, 24 Filling gas discharge part, 25 Supply connector, 26 Discharge connector, 30 Cooling water, 31 Water cooling pipe hole , 40 Utility supply unit, 45 Process gas supply unit, 50 Spacer, 60 Diffusion plate built-in shower plate, 70 Process gas reservoir, 80 Substrate to be processed, 81 Transport means, A, B plasma, X, Y, Z, X1 gap.

Claims (9)

By applying a predetermined voltage between a pair of electrode portions opposed to each other, an additive gas for performing a predetermined plasma treatment introduced into a region between the pair of electrode portions and the additive gas are diluted. An electrode structure of a plasma processing apparatus for performing plasma processing on a member to be processed by converting the processing gas containing a dilution gas into plasma and exposing the member to be processed to the generated plasma atmosphere,
Each of the pair of electrode portions is
An electrode body made of a metal to which a voltage is applied;
A covering member that is formed of a fixed dielectric and accommodates the electrode body, and covers the electrode body so as to surround the electrode body by disposing the electrode body in the space;
An electrode structure of a plasma processing apparatus, comprising: a filling gas introduction portion for filling the space of the covering member in which the electrode main body is accommodated with a predetermined gas having a discharge start voltage higher than the dilution gas.   The electrode structure of the plasma processing apparatus according to claim 1, further comprising a filling gas supply unit that sends the filling gas to the filling gas introduction unit.   The electrode structure of the plasma processing apparatus according to claim 1, wherein a pressure in the space of the covering member filled with the filling gas is set higher than a pressure outside the covering member. The covering member is
A case member having a recess for housing the electrode body;
The electrode structure of the plasma processing apparatus in any one of Claims 1-3 containing the cover member which plugs up the said recessed part in the state which accommodated the said electrode main body.   The electrode structure of the plasma processing apparatus according to claim 4, wherein the covering member includes a sealing member interposed between the case member and the lid member. The filling gas is at least selected from the group consisting of nitrogen (N ₂ ), oxygen (O ₂ ), flon, carbon tetrafluoride (CF ₄ ), carbon dioxide (CO ₂ ), and sulfur hexafluoride (SF ₆ ). The electrode structure of the plasma processing apparatus according to any one of claims 1 to 5, wherein any one of the gases is used. The at least one gas selected from the group consisting of helium (He), argon (Ar), neon (Ne), xenon (Xe), and nitrogen (N ₂ ) is used as the dilution gas. The electrode structure of the plasma processing apparatus in any one of 6.   The electrode structure of the plasma processing apparatus according to claim 1, wherein the same type of gas as the additive gas is used as the filling gas. By applying a predetermined voltage between a pair of electrode portions opposed to each other, an additive gas for performing a predetermined plasma treatment introduced into a region between the pair of electrode portions and the additive gas are diluted. A plasma processing apparatus having an electrode structure for performing plasma processing on a member to be processed by converting the processing gas containing a dilution gas into plasma and exposing the member to be processed to the generated plasma atmosphere,
Each of the pair of electrode portions is
An electrode body made of a metal to which a voltage is applied;
A covering member formed of a fixed dielectric material and containing the electrode body, and covering the electrode body so as to surround the electrode body by disposing the electrode body in the space;
A plasma processing apparatus, comprising: a filling gas introduction unit for filling the space of the covering member in which the electrode main body is accommodated with a predetermined gas having a discharge start voltage higher than the dilution gas.

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