JP2007251223A - Plasma processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing device having a high degree airtightness which can perform its initialization efficiently, and also to provide an initializing method thereof. <P>SOLUTION: The plasma processing device comprises a processing chamber for processing an object to be processed; a susceptor 153 (a mounting table) for mounting the object to be processed which is disposed in the processing chamber; a gas inlet for receiving a processing gas into the processing chamber; an antenna (a coil 157) for producing plasma in the chamber by exciting the processing gas; a dielectric wall; and a sealing member for airtightly sealing the dielectric wall and the processing chamber; wherein the sealing member is set in between the sealing surface of the dielectric wall and the sealing surface of the processing chamber, and a protruded portion 179 is formed on the upper and bottom surfaces of the sealing member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus and an initialization method thereof. In particular, the plasma processing apparatus can be efficiently initialized after cleaning the plasma processing apparatus, when performing another process, or for preventing particle generation. The present invention relates to a plasma processing apparatus and an initialization method thereof.

  In the manufacture of semiconductor devices, high density and high integration have recently been advanced. For this reason, the design rule becomes stricter, for example, the line width of a gate wiring pattern or the like is further reduced, and the contact hole that is a connection portion between the lower semiconductor device and the upper wiring layer is increasing in aspect ratio.

  Thus, management of the manufacturing process is important for manufacturing a semiconductor device designed with strict design rules. For example, in the etching process, contact holes having a fine pattern and a high aspect ratio must be reliably etched. For this reason, it is indispensable to control the etching rate and reliably form a desired pattern.

  However, in a plasma processing apparatus that performs etching, particularly a plasma processing apparatus that uses inductively coupled plasma (hereinafter referred to as ICP), no potential is applied to a chamber made of, for example, quartz. Easy to adhere as foreign matter. The foreign matter adhering to the inner wall of the chamber affects the plasma state during etching and causes the etching rate to fluctuate.

In particular, various processes may be performed in order to meet various requirements accompanying the progress of semiconductor devices. For example, before the contact hole is filled with a material such as tungsten, it is necessary to etch an oxide film (for example, SiO ₂ ) generated by oxidizing or altering the bottom surface of the contact hole. However, when a conductive material other than the oxide film that is normally etched, such as Poly-Si, W, WSi, or CoSi, is etched, the oxide film is etched again to cause a phenomenon called a memory effect.

  The memory effect is the following phenomenon. For example, when a film made of a metal material such as CoSi is etched, the etched substance adheres to a chamber made of quartz material or its inner wall, and electrons and ions generated in the plasma are grounded via the deposit. This makes the plasma unstable and is affected by the plasma state. Therefore, immediately after that, even if etching is performed under the same conditions using an oxide film as a target, the plasma is unstable, and the steady-state etching rate is not achieved. In other words, if something other than the film that is normally etched is etched, a material different from that normally deposited on the chamber and its inner wall will be deposited, which will change the impedance to the plasma, which in turn will affect the plasma state, resulting in a memory effect. Will be caused.

  FIG. 18 is a schematic cross-sectional view showing an example of the semiconductor wafer mounting unit 10 in the conventional plasma processing apparatus. As shown in FIG. 18, the semiconductor wafer mounting part 10 has a guide ring 80 and a susceptor 153a.

The susceptor 153a is made of, for example, AlN. The guide ring 80 is made of, for example, a quartz material such as SiO ₂ and has a shape that surrounds the outer periphery of the susceptor 153a. It is configured so that it can be placed.

In the plasma processing apparatus having the semiconductor wafer mounting portion 10 as described above, for example, when etching a semiconductor wafer of a normal SiO ₂ film, the surface of the semiconductor wafer whose surface is covered with Poly-Si is halfway. After the etching, when the wafer having the SiO ₂ surface is subsequently etched, the etching rate is lowered. In this case, for example, a situation occurs in which the normal etching rate is not restored unless the processing of five semiconductor wafers of SiO ₂ film (equivalent to 150 seconds as an etching time) is performed.

This is because the plasma state, which was attenuated because Poly-Si Si scattered and adhered to the inner wall surface of the chamber, was etched again to some extent inside the chamber by etching several semiconductor wafers of SiO ₂ film, This is probably because the plasma state returns to the original steady state.

  Therefore, in order to return the etching rate to a steady state, etching using a dummy wafer is performed. However, in order to prepare a dummy wafer, time, labor, and cost are indispensable, which is not preferable in terms of deteriorating production and work efficiency.

In addition, the deposit attached to the inner wall of the chamber is difficult to remove by cleaning using, for example, ClF ₃ gas. Even if it is performed, a certain number of dummy wafers are used to return the apparatus to a steady state. Etching must be done.

  In addition, when multiple semiconductor wafers are etched, the operating time of the equipment becomes longer, so that the deposits attached to the inner wall of the chamber become thicker and peel off due to film stress, or due to ions and radicals in the processing gas. The deposits may be generated as particles when they are peeled off due to stress such as reduction or erosion.

  In such a case, it is also known that the generation of particles can be suppressed by performing plasma treatment using a wafer whose surface is covered with an oxide film as a dummy wafer and depositing oxide on the inner wall of the chamber. However, this work is also not preferable from the viewpoint of production and work efficiency.

  Further, since the guide ring 80 disposed around the susceptor 153a is configured such that the upper surface is positioned above the susceptor 153a, the plasma is disturbed around the wafer, and plasma such as film formation and etching is generated. There was also a problem that the in-plane uniformity of processing was impaired.

  Conventionally, an O-ring or a flat or L-shaped gasket having both surfaces formed flat has been used to seal between a dielectric wall, in particular, a bell jar type dielectric wall and a processing chamber.

  However, when an O-ring is used, it is necessary to protect other than the contact surface of the O-ring to prevent damage. In addition, when a flat or L-type gasket is used, there is a problem in that a sufficient surface pressure cannot be secured on the seal surface and vacuum leakage is likely to occur.

  Furthermore, conventionally, when processing gas is introduced into the processing chamber, the gas is introduced from the ceiling using a so-called shower head having a structure in which a plurality of gas introduction holes are formed in the ceiling.

  However, in the showerhead structure, the distance between the wafer and the gas introduction hole is limited according to the structure of the processing apparatus, and the gas distribution on the outer periphery of the wafer changes, so that the plasma processing such as film formation and etching is uniform in the surface. There was a problem of impairing sex.

  The present invention has been made in view of the above problems of the conventional plasma processing apparatus and its initialization method, and an object of the present invention is to efficiently start up the apparatus and to etch materials other than oxide films. It is an object of the present invention to provide a new and improved plasma processing apparatus and an initialization method thereof that can appropriately perform the above-described process and prevent generation of particles.

  Furthermore, another object of the present invention is to provide a new and improved plasma processing apparatus capable of preventing metal contamination based on the material composition of members constituting the apparatus such as a mounting table in the processing apparatus. It is.

  Furthermore, another object of the present invention is to improve the in-plane uniformity of plasma processing such as film formation and etching by making the gas flow uniform on the wafer and uniformly distributing the plasma over the entire processing surface. It is an object of the present invention to provide a plasma processing apparatus having a new and improved gas introduction structure capable of achieving the above.

  In order to solve the above problems, according to the present invention, in a plasma processing apparatus configured to excite induction plasma in a processing chamber through a dielectric wall, a mounting table for mounting a processing target in the processing chamber is provided. There is provided a plasma processing apparatus including a dielectric member, for example, quartz, capable of detachably covering at least a mounting surface.

According to such a configuration, when trouble such as generation of particles occurs during processing in the plasma processing apparatus, the inside of the chamber is wet.
When cleaning is performed or when periodic maintenance is performed, or when moving to another process, such as when shifting from an object to be etched, such as metal etching to oxide film etching, and further inside the chamber Etching the dielectric member placed on the mounting table in the plasma when returning to the initial state can efficiently initialize the chamber of the plasma processing apparatus without using a dummy wafer. Since the mounting surface is covered with a dielectric material, the chamber and the object to be processed are prevented from being contaminated by the metal even if the material constituting the mounting table contains impurities such as metal. Can do.

  Further, a guide ring for guiding the object to be processed may be formed around the mounting surface of the dielectric member, and the surface of the guide ring is formed at a position lower than the processing surface of the object to be processed. It may be. The dielectric member can have a concave shape that can be placed on the top of the mounting table. Furthermore, the dielectric member may be configured as an assembly including a mounting surface portion and a guide ring portion that are separable from each other.

  According to such a configuration, the object to be processed and the dielectric member can be accurately placed, the plasma can be made uniform on the processing surface of the object to be processed, and the manufacturing and consumption of the dielectric member can be performed. Time exchange becomes easy.

  According to still another aspect of the present invention, in a plasma processing apparatus configured to excite induction plasma in a processing chamber via a dielectric wall, for example, a bell jar-shaped dielectric wall, the dielectric wall, the processing chamber, A plasma processing apparatus is provided in which a flat gasket made of a fluorine-based elastomer material and having at least one row of annular protrusions formed on both sides thereof is disposed between the two.

  According to such a configuration, it is possible to protect the entire sealing surface and to secure an appropriate surface pressure, and thus it is possible to provide a plasma processing apparatus with higher airtightness.

  Further, according to another aspect of the present invention, in a plasma processing apparatus configured to perform plasma processing on an object to be processed disposed in a processing chamber, a gap between a sidewall of the processing chamber and a ceiling portion is provided. A plasma processing apparatus is provided, characterized in that a gas introduction ring having a plurality of gas ejection holes opened toward the upper side of the processing chamber is disposed.

  The gas ejection hole may be opened in an upward tapered surface, and the gas ejection hole may be opened toward one point of the processing chamber. The plasma processing apparatus excites inductive plasma in the processing chamber via a bell jar type dielectric wall, and the ceiling portion may be a bell jar type dielectric wall.

  According to such a configuration, gas can be uniformly ejected from a side surface of the processing chamber toward a predetermined position of the processing chamber, for example, a central portion. As a result, the gas flow becomes uniform on the wafer, the plasma is also generated uniformly, and the in-plane uniformity of plasma processing such as film formation and etching can be improved.

  Furthermore, the dielectric member is configured to excite induction plasma in the processing chamber through the dielectric wall, and can detachably cover at least the mounting surface of the mounting table on which the target object is mounted in the processing chamber. An initialization method for a plasma processing apparatus comprising a plasma processing apparatus, wherein the plasma processing apparatus is stabilized by exciting the plasma in the processing chamber for a predetermined time with the dielectric member exposed. An initialization method of a plasma processing apparatus that can be generated is provided. The initialization of the plasma processing apparatus is performed when shifting to another process, when starting up the plasma processing apparatus, or when particles are generated. At the time of initialization, Ar gas plasma may be excited in the processing chamber so that the plasma is stably generated.

  According to the above method, the initialization of the plasma processing apparatus can be performed efficiently in terms of the operating rate, and since it is effective in preventing the generation of particles, a highly reliable process is possible.

  As described above, according to the present invention, a new and improved plasma processing apparatus capable of efficiently starting up the apparatus and shifting to another process and preventing the generation of particles, and its An initialization method can be provided.

  Exemplary embodiments of a plasma processing apparatus and an initialization method thereof according to the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a schematic view showing a plasma processing apparatus according to a first embodiment of the present invention. As shown in FIG. 1, the plasma processing apparatus 150 is an etching apparatus that removes an oxide film or other material film on a semiconductor wafer, and can employ an inductively coupled plasma (ICP) system.

  The apparatus 150 includes a substantially cylindrical chamber 151 and a substantially cylindrical bell jar 152. The bell jar 152 is airtightly provided above the chamber 151 via a gasket 179 described later. The bell jar 152 is made of a dielectric material such as quartz or a ceramic material.

  A susceptor 153 is provided in the chamber 151. The susceptor 153 is for horizontally supporting a semiconductor wafer (hereinafter simply referred to as a wafer) 1 as an object to be processed. A dielectric member 180 according to the present embodiment is disposed on the upper surface of the susceptor 153, and the detailed structure thereof will be described later. The dielectric member 180 is supported by the susceptor 153. However, in order to support the dielectric member 180 more reliably, a shaft 184 standing from the bottom surface of the chamber 151 is provided to support the dielectric member 180 as shown in FIG. Also good. There may be one shaft 184 or a plurality of shafts. For example, three or four shafts 184 that support a portion of the dielectric member 180 that protrudes outward from the susceptor 153 may be provided, and the shafts 184 may be arranged at equal intervals in the circumferential direction of the dielectric member 180.

  The support member 154 has a substantially cylindrical shape and supports the susceptor 153. The heater 156 is embedded in the susceptor 153 to heat the wafer 1. The power source 175 supplies power to the heater 156 via the power connection line 177.

  The coil 157 is wound around the bell jar 152 as an antenna member. The high frequency power source 158 is connected to the coil 157 via the matching unit 159. The high frequency power source 158 can generate high frequency power having a frequency of, for example, 450 kHz to 60 MHz (preferably 450 kHz to 13.56 MHz).

  Here, the configuration of the upper part of the bell jar 152 will be described. FIG. 3 is a schematic cross-sectional view showing the configuration of the upper portion of the bell jar 152, and FIG. 4 is an enlarged view of a portion P shown in FIG. As shown in FIG. 3, a counter electrode 201 with respect to the susceptor 153 is provided at an upper portion outside the bell jar 152. The counter electrode 201 is made of Al or the like, and is provided between the bell jar 152 via a cap 203 and a spacer ring 205 for preventing buffering with the bell jar 152 disposed in the center. The cap 203 and the spacer ring 205 are made of a resin such as Teflon (registered trademark) and press the bell jar 152 so as to be sealed.

  The counter electrode 201 is connected to an Al cover 207 provided thereon, and the cover 207 is further connected to an Al sheath cover 209 that covers the side surface of the bell jar 152. The counter electrode 201 is grounded through a cover 207 and a sheath cover 209.

  A matching unit 159 is provided further above the cover 207, and is electrically connected to the coil 157 via a portion P in FIG. As shown in FIG. 4, the P portion includes an electrode 211 connected to the matching unit 159, an electrode 213 connected to the electrode 211, an electrode 215 connected to the electrode 213, and an electrode connected to the electrode 215 by a screw 219. 217, each electrode can be removed. Further, the electrode 217 is connected to the clip 221, and the clip 221 pinches the coil 157, whereby the matching unit 159 and the coil 157 are electrically connected.

  The clip 221 only needs to have a function of electrically connecting the electrode 217 and the coil 157, and the connecting portion 223 may be connected to the coil 157 with a screw 225 as shown in FIG. 5. As the electrodes 213 and 215, copper coated with silver or the like is used. The outside of the electrodes 213 and 215 is covered with a cover 227 made of a heat-resistant resin such as an amide resin, and further covered with an Al cover 229. As described above, an induction electromagnetic field is formed in the bell jar 152 by supplying high-frequency power from the high-frequency power source 158 to the coil 157 via the matching unit 159.

Gas supply mechanism 160 includes of H ₂ supply source 162 for supplying of H ₂ for reducing an oxide of Ar supply source 161, and the metal material supplying Ar for etching a semiconductor wafer surface. The gas lines 163 and 164 are connected to gas supply sources 161 and 162, respectively. Valves 165 and 178 and a mass flow controller 166 are provided in each line.

The gas introduction ring 167 is provided in an annular shape between the bell jar 152 and the ceiling portion of the side wall of the chamber 151, and the process gas is directed in the direction indicated by the arrow, that is, toward the center (α point) of the space 155 in the bell jar 152. It can be ejected and is airtightly fixed to the upper part of the side wall of the chamber 151 by a bolt or the like via a gasket 179. A plurality of gas introduction holes 167 a are formed in the inner peripheral side wall surface of the gas introduction ring 167 to eject process gas toward the substantially central portion of the space portion 155. The gas introduction hole 167a is disposed at an angle at which the processing gas is ejected toward the central portion of the space portion 155 at a position half the number of turns of the induction coil (coil height) disposed outside the bell jar 152. Yes. Further, since the gas introduction holes 167a are arranged at equal intervals, the processing gas can be ejected uniformly into the space portion 155 of the bell jar 152.
The number of the gas introduction holes 167a is not limited to this, and the number and the ejection uniform angle are adjusted so as to form a uniform flow according to the size of the apparatus. In this embodiment, 20 are formed. Further, the uniform ejection angle of the gas introduction hole 167a can be set arbitrarily according to the molding angle, and may be an angle (fixed) toward the central portion of the space portion 155, that is, the upper portion of the semiconductor wafer.

  As shown in FIG. 6, the gas introduction ring 167 is provided with a gas passage 167d communicating with an annular groove 167b, and gas lines 163 and 164 are connected to the gas passage 167d. Gases from the gas lines 163 and 164 are injected into the gas introduction ring 167 via the gas passage 167d, and an etching gas is introduced toward the center of the space 155 via the gas introduction hole 167a.

  As shown in FIG. 6, the gas introduction ring 167 can be configured such that the side surface 167c on the space 155 side is formed vertically and the gas introduction hole 167a is opened in the side surface 167c which is the vertical surface. However, in such a configuration, a speed difference is generated between the gas flow A ejected from the upper portion of the hole and the gas flow B ejected from the lower portion of the hole. Therefore, when the processing gas is ejected from the gas introduction hole 167a, Since a turbulent flow (spiral flow) is formed near the outlet of the gas introduction hole 167a, the gas cannot be uniformly introduced into the space portion 155.

  Accordingly, as shown in FIG. 7, a tapered surface 167f is formed on the side surface 167c of the gas introduction ring 167 on the space 155 side, and the gas introduction hole 167a formed upward with respect to the tapered surface 167f is substantially perpendicular. The gas flow is ejected from the upper part of the hole by opening the hole and further adjusting the angle so that the direction of the gas introduction hole 167a is half the number of turns of the induction coil (coil height). The difference in velocity between A and the gas flow B ejected from the lower part of the hole can be reduced, and the gas can be uniformly introduced into the chamber. Further, the vicinity of the outlet of the gas introduction hole 167a on the space 155 side is preferably chamfered like the outlet 167g so as to reduce the resistance at the time of gas ejection.

  Next, the configuration of the gas passage 167d for introducing gas into the groove 167b in the gas introduction ring 167 will be described with reference to FIG. FIG. 8 is a diagram showing the configuration of the gas passage 167d, in which FIG. 8A is an overview from above, FIG. 8B is an overview from the Q direction of FIG. c) is a schematic view of the RR cross section of FIG.

  As shown in FIG. 8, the gas introduction ring 167 is provided with a gas passage 167d for introducing gas into the internal groove 167b. As shown in FIG. 8B, an inlet of a gas passage 167d is provided outside the gas introduction ring 167. A horizontal hole 167h is provided in the upper part of the connection portion between the gas passage 167d and the groove 167b, and the side wall of the groove 167b at the connection portion between the gas passage 167d and the groove 167b is closed. The gas introduced from the gas passage 167d passes through the lateral hole 167h and is introduced into the groove 167b. With this configuration, gas easily flows in the circumferential direction of the groove 167b, and when a plurality of gas introduction holes 167a are formed in the gas introduction ring 167, the gas ejected toward the space portion 155 is made more uniform. effective.

  Further, the connecting portion between the side wall of the chamber 151 and the side wall of the bell jar 152 is airtightly connected through a gasket 179 in order to maintain the degree of vacuum. FIG. 9 is a cross-sectional view of a gasket according to an embodiment of the present invention. As shown in FIG. 9, the gasket 179 is provided between the sealing surface of the bell jar 152 and the sealing surface of the upper portion of the gas introduction ring 167. Thereby, airtightness is maintained, and further, the sealing surface of the bell jar 152 can be protected and damage can be prevented. Further, the gasket 179 may be made of, for example, a fluorine-based elastomer material for the purpose of maintaining airtightness. A semicircular mountain or a mountain-shaped projection 179a, 179b is formed on the upper and lower surfaces of the ring-shaped gasket. It is good also as the shape which shape | molded. The lower surface of the gasket 179 may not have the protrusion 179a, and the upper surface of the gasket 179 may have a plurality of protrusions 179a.

  An exhaust device 169 including a vacuum pump is connected to the exhaust pipe 168. A part of the bottom wall of the chamber 151 is open, and a concave exhaust part 182 is airtightly connected to the opening. The exhaust pipe 168 is connected to the side opening of the exhaust part 182. A support member 154 for supporting the susceptor 153 is provided at the bottom of the exhaust part 182. Then, the exhaust device 169 can be operated to depressurize the interior of the chamber 151 and the bell jar 152 to a predetermined degree of vacuum via the exhaust unit 182 and the exhaust pipe 168.

  A gate valve 170 is provided on the side wall of the chamber 151. The wafer 1 is transferred between adjacent load lock chambers (not shown) with the gate valve 170 open. Further, the electrode 173 embedded in the susceptor 153 is connected to the high frequency power source 171 via the matching unit 172 so that a bias can be applied.

A processing operation in the plasma processing apparatus configured as described above will be described. First, the gate valve 170 is opened, the wafer 1 is inserted into the chamber 151, and the lifter pin lifting / lowering drive unit 181b of the lifter pin drive mechanism 181 raises the lifter pin 181a, and the lifter pin 181a receives the wafer 1. After that, the lifter pins 181 a are lowered to place the wafer 1 on the susceptor 153. Thereafter, the gate valve 170 is closed, and the exhaust device 169 exhausts the chamber 151 and the bell jar 152 to a predetermined reduced pressure state. Subsequently, while supplying Ar gas and H ₂ gas from the Ar supply source 161 and H ₂ supply source 162 into the chamber 151, high-frequency power is supplied from the high-frequency power source 158 to the coil 157 and guided to the space 155 in the bell jar 152. Create an electromagnetic field.

Plasma is generated in the space 155 in the bell jar 152 by this induction electromagnetic field, and for example, an oxide film on the surface of the wafer 1 is removed by etching. For example, when H ₂ gas is used, the heater 156 may be heated by supplying power from the power source 175 as necessary. A bias voltage may be applied from the high frequency power source 171 to the susceptor 153.

An example of processing conditions at this time is, for example, a pressure of 0.1 to 13.3 Pa, preferably 0.1 to 2.7 Pa, a wafer temperature of 100 to 500 ° C., a gas flow rate of Ar of 0.001 to 0.03 L / min, preferably 0.005 to 0.015 L / min, H ₂ is 0 to 0.06 L / min, preferably 0 to 0.03 L / min, and the frequency of the high frequency power source 158 of the plasma processing apparatus 150 is 450 kHz to 60 MHz, preferably 450 kHz to 13.56 MHz, and a bias voltage of −20 to −200 V (0 to 500 W). By processing for about 30 seconds with the plasma under such conditions, for example, about ₂ to 10 nm of SiO ₂ is removed as an oxide film.

  FIG. 2 is a schematic cross-sectional view showing the semiconductor wafer mounting part 100 according to the first embodiment. As shown in FIG. 2, the semiconductor wafer mounting unit 100 includes a susceptor 153 and a dielectric member 180.

The susceptor 153 is made of, for example, AlN, Al ₂ O ₃ , SiC material, or the like. The dielectric member 180 is made of a material that maintains the dielectric during plasma processing, such as SiO ₂ , Al ₂ O ₃ , AlN, or Si ₃ N ₄ . A dielectric member 180 can be placed on the susceptor 153. As an example, the dielectric member 180 in the present embodiment uses quartz.

  The dielectric member 180 on the upper surface portion of the susceptor 153 has a thickness t1, which is difficult to process if it is too thin, inferior in durability, and expensive if it is thick, for example, about 0.5 to 5 mm. , Preferably 0.5 to 1 mm.

  At the center of the upper surface of the dielectric member 180 that covers the outer peripheral portion of the susceptor 153, a step t2 that is concave on the lower side is provided, so that the outer periphery of the wafer 1 can be guided and placed at a precise position. ing. Since the thickness of the wafer 1 is about 0.7 mm, the level difference t2 is, for example, about 0.5 to 3 mm, preferably 1 to 3 mm, and more preferably the same level as the wafer level.

  The dielectric member 180 has an outer diameter larger than that of the susceptor 153, and is provided with an outer edge portion 180 a that protrudes outward from the susceptor 153 when placed on the susceptor 153. In addition, the dielectric member 180 has a convex portion 180 n that protrudes downward at the center thereof, and is accommodated in a concave portion 153 n that is concave on the upper side provided in the susceptor 153.

  Specifically, for example, the concave portion 153n of the susceptor 153 is a spot facing as shown in FIG. 2, the convex portion 180n of the dielectric member 180 abuts on the concave portion 153n of the susceptor 153, and the dielectric material is formed on the upper surface of the edge portion of the susceptor 153. You may make it the lower surface of the outer edge part 180a of the member 180 contact | abut. As a result, the dielectric member 180 can be stably placed on the susceptor 153 without falling off the susceptor 153.

  In the plasma processing apparatus 150 having such a semiconductor wafer mounting unit 100, plasma processing is conventionally performed using a dummy wafer in order to initialize the memory effect or prevent the generation of particles. Instead, for example, while the wafer 1 is being carried in and out, the dielectric member 180 is etched without placing the wafer 1 thereon. This is called after-process processing.

Actually, the output of the high frequency power source 158 for ICP is 200 to 1000 W (preferably 200 to 700 W), the output of the power source 171 for bias voltage is 100 to 500 W (preferably 400 W), its frequency is 13.56 MHz, pressure It is preferable to use only Ar gas at about 0.1 to 1.33 Pa (preferably 0.67 Pa), and the flow rate of Ar gas is 0.001 to 0.06 L / min (preferably 0.001 to 0.003). (03 L / min, or 0.038 L / min) The susceptor temperature is -20 to 500 ° C., preferably 200 ° C. (when using a mixed gas of Ar gas and H ₂ gas, the susceptor temperature is 500 ° C.). The processing time is 5 to 30 seconds, for example, about 10 seconds is preferable. By etching the dielectric member under such processing conditions and attaching the dielectric member to the inner wall surface of the bell jar, the memory effect and the generation of particles can be prevented.

  Here, the particle generation mechanism and the memory effect will be described with reference to FIGS. FIG. 10 is an element composition analysis diagram by SEM-EDX (scanning electron microscope with energy dispersive X-ray spectrometer), FIG. 11 is a conceptual diagram of particle generation, and FIGS. 12 and 13 are fluctuations in etching amount due to the memory effect. FIG.

FIGS. 10A, 10B, and 10C are elemental composition analysis diagrams of Si, bell jar 152 sidewall deposits, and SiO ₂ , respectively. As shown in FIG. 10, the ratios of Si element: O element detected from Si, the bell jar 152 side wall deposit, and SiO ₂ are 100: 0, 49:46, and 34:66, respectively. Therefore, the deposit on the side wall of the bell jar 152 is presumed to be SiO because the Si element and the O element are contained in about 1: 1.

SiO is deposited on the side wall of the bell jar 152, as shown in FIG. 11A, when etched SiO ₂ exists in the space 155 in the bell jar 152, the hydrogen gas in the processing gas is dissociated from the plasma. This is thought to be due to reduction by H ⁺ generated to form SiO.

As shown in FIG. 11B, when a large amount of SiO is deposited due to the processing of a large number of wafers, a film like a deposit 315 is formed. As shown in FIG. 11C, such a Si-rich SiO film is peeled off like a deposit 317 due to stress when it reaches a certain film thickness, which becomes particles. Therefore, as described above, it is preferable that the after-process treatment for suppressing the generation of particles is performed only with Ar gas that does not reduce SiO ₂ .

FIGS. 12 and 13 show the etching amounts when processing is performed under the same etching conditions. As shown in FIG. 12, the first semiconductor wafer is etched with SiO ₂ to obtain _two wafers. When COSi ₂ and Poly-Si are respectively etched on the semiconductor wafer of the eye, even if SiO ₂ is etched on the third wafer, a memory effect is generated that changes from the initial etching amount.

It is considered that this memory effect is caused when the plasma generated is unstable when different materials are etched because the materials attached to the inner wall of the chamber are different. When the memory effect occurs in this way, if the above-mentioned after-process processing is performed before the next processing (here, etching of the fourth semiconductor wafer), COSi ₂ or Poly-Si as shown in the figure. It turns out that it returns to the etching amount before etching. This is considered to be because the inner wall of the chamber is again covered with the original material and the plasma state is stabilized. Thus, after-process processing has the effect of eliminating the memory effect.

  Further, when the dielectric member 180 is processed under the above-described conditions for the after process, the following results are obtained with respect to the plasma processing time required for returning to the steady state etching rate.

The chamber is maintained for about 150 seconds for measures against the memory effect after etching conductive materials other than oxide films, such as Poly-Si (polysilicon) and CoSi ₂ (cobalt silicon, cobalt silicide). In this case, it took about 300 seconds for initialization after wet cleaning using chemicals, and about 1500 seconds for particle prevention. By etching the dielectric member for tens of seconds, , The inside of the chamber can be returned to a steady state, and optimum etching becomes possible.

In particular, when the etching of the silicon oxide film is repeatedly performed with a plasma of a mixed gas of Ar gas and H ₂ gas used as the processing gas, the sputtered SiOx adheres to the inner wall of the processing chamber and the member surface in the processing chamber, and the processing gas H _{It is considered that the two} gases are dissociated from the plasma and H ⁺ and H ^* are generated and eroded. Therefore, for example, the dielectric member 180 made of SiO ₂ or the like is subjected to plasma treatment, and the inner wall of the processing vessel or the surface of the member in the processing vessel is newly covered with a dielectric material such as SiO _{2 to} obtain a surface state in which particles are hardly generated. Particle generation can be suppressed. In the plasma treatment for preventing particles, it is preferable to use Ar gas as a treatment gas.

  In addition, if processing is performed using a dummy wafer, the above processing time is about 30 seconds per sheet for measures against the memory effect, initialization after wet cleaning using chemicals, and particle prevention. , Which corresponds to about 5, 10 and 50 sheets, respectively. As described above, according to the plasma processing apparatus and the initialization method for processing the dielectric member 180 according to the present embodiment, measures against the memory effect, initialization after wet cleaning using a chemical agent, and particle prevention are provided. This eliminates the need to prepare dummy wafers and improves work and production efficiency. The dielectric member 180 can be replaced when it is consumed after etching.

(Second Embodiment)
FIG. 14 is a schematic cross-sectional view showing a semiconductor wafer mounting unit 500 according to the second embodiment. As shown in FIG. 14, the semiconductor wafer mounting unit 500 can be used in place of the semiconductor wafer mounting unit 100 in the plasma processing apparatus 150. The same components and functions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

The susceptor 153a has a convex center and is made of, for example, AlN. The dielectric member 580 is made of a material that maintains a dielectric during plasma processing, such as SiO ₂ , Al ₂ O ₃ , AlN, or Si ₃ N _4, and has a shape that covers the entire susceptor 153 a. The dielectric member 580 on the upper surface of the susceptor 153a has a thickness t1, and if it is too thin, it is difficult to process, is inferior in durability, and a thick one is costly, for example, about 0.5 to 5 mm. Preferably, it can be 1 to 3 mm.

  A step t2 is provided on the upper surface of the dielectric member 580 covering the outer peripheral portion of the susceptor 153a, so that the outer periphery of the wafer 1 can be guided and placed at an appropriate position. Since the thickness of the wafer t1 is about 0.7 mm, the level difference t2 is, for example, about 0.5 to 3 mm, preferably 1 to 3 mm, and more preferably the same level as the thickness of the wafer.

  In the plasma processing apparatus 150 having such a semiconductor wafer mounting section 500, the wafer 1 is mounted instead of the processing conventionally performed using a dummy wafer for the initialization of the memory effect and the wet processing or the prevention of particle generation. The dielectric member 580 is etched without being placed.

  Etching conditions, required time, and the like are the same as those in the first embodiment, but the dielectric member 580 is configured to cover the susceptor 153a, and therefore does not need to be supported by the shaft. Moreover, it is preferable to use Ar gas as a processing gas at the time of plasma processing for preventing particle generation.

(Third embodiment)
FIG. 15 is a schematic cross-sectional view showing a semiconductor wafer mounting portion 600 according to the third embodiment. As shown in FIG. 15, the semiconductor wafer mounting unit 600 can be used in place of the semiconductor wafer mounting unit 100 in the plasma processing apparatus 150. The same reference numerals are given to the same configurations and functions as those in the first and second embodiments, and the description thereof will be omitted.

The semiconductor wafer mounting unit 600 includes a susceptor 153 a and dielectric members 680 and 682. The dielectric members 680 and 682 are made of a material that maintains dielectricity during plasma processing, such as SiO ₂ , Al ₂ O ₃ , AlN, or Si ₃ N _4, and have a shape that covers the entire susceptor 153 a.

  The dielectric member 680 has a thickness t1, which is difficult to process if it is too thin, is inferior in durability, and is thick, for example, about 0.5 to 5 mm, preferably 1 to 3 mm, considering the cost. can do.

  A step t3 is provided on the upper surface of the dielectric member 682 covering the outer periphery of the susceptor 153a, and the outer periphery of the dielectric member 680 and the wafer 1 can be guided and placed at an appropriate position. Since the thickness of the dielectric member 680 is about 0.5 to 3 mm and the thickness of the wafer 1 is about 0.7 mm, the step t3 is, for example, about 1 to 4 mm, preferably the same level as the surface of the wafer. It is good to be a surface.

  In the plasma processing apparatus 150 equipped with such a semiconductor wafer mounting unit 600, the wafer 1 is replaced with a process that is conventionally performed using a dummy wafer for initialization of the memory effect and wet processing, or for prevention of particle generation. The dielectric member 680 is etched without mounting.

  Etching conditions and required time are the same as those in the first and second embodiments. However, since the dielectric member is an assembly of two parts, the processing at the time of manufacturing can be performed compared to the dielectric member 580. It is easy to replace, and has an effect of facilitating replacement when consumed by etching. Moreover, it is preferable to use Ar gas as a processing gas at the time of plasma processing for preventing particle generation.

(Fourth embodiment)
FIG. 16 is a schematic cross-sectional view showing a semiconductor wafer mounting portion 700 according to the fourth embodiment. As shown in FIG. 16, the semiconductor wafer mounting unit 700 can be used in place of the semiconductor wafer mounting unit 100 in the plasma processing apparatus 150. The same components and functions as those in the first, second, and third embodiments are denoted by the same reference numerals, and description thereof is omitted.

The semiconductor wafer mounting unit 700 includes a susceptor 153a and dielectric members 780 and 782. The dielectric members 780 and 782 are made of a material that maintains dielectricity during plasma processing, such as SiO ₂ , Al ₂ O ₃ , AlN, or Si ₃ N _4, and have a shape that covers the entire susceptor 153 a.

  The upper surface portion of the susceptor 153a of the dielectric member 780 has a thickness t1, and if it is too thin, it is difficult to process, is inferior in durability, and a thick one is, for example, about 0.5 to 5 mm in consideration of cost. can do.

  A step t2 is provided on the upper surface of the dielectric member 780 that covers the outer peripheral portion of the susceptor 153a, and is configured so that the outer periphery of the wafer 1 can be guided and placed at an appropriate position. Since the thickness of the wafer 1 is about 0.7 mm, the step t <b> 2 is, for example, about 0.5 to 3 mm, preferably the same level as the wafer surface.

  In the plasma processing apparatus 150 equipped with such a semiconductor wafer mounting portion 700, the wafer 1 is replaced with the processing that has been conventionally performed using a dummy wafer for the initialization of the memory effect and the wet processing, or the prevention of particle generation. The dielectric member 780 is etched without mounting.

  Etching conditions and required time are the same as in the previous embodiment, but the dielectric member is an assembly of two parts, so that it is easier to replace when the dielectric member is consumed by etching than the dielectric member 580. In addition, compared with the dielectric members according to the second and third embodiments, the same effect can be obtained with a small amount of material. At the time of plasma processing for preventing particle generation, it is preferable to use Ar gas as a processing gas.

(Fifth embodiment)
FIG. 17 is a schematic cross-sectional view showing a semiconductor wafer mounting portion 800 according to the fifth embodiment. As shown in FIG. 17, the semiconductor wafer mounting unit 800 can be used in place of the semiconductor wafer mounting unit 100 in the plasma processing apparatus 150. The same components and functions as those in the first, second, third, and fourth embodiments are denoted by the same reference numerals, and description thereof is omitted.

The semiconductor wafer mounting unit 800 includes a cylindrical susceptor 153 b and a dielectric member 880. The dielectric member 880 is made of a material that maintains dielectricity during plasma processing, such as SiO ₂ , Al ₂ O ₃ , AlN, or Si ₃ N _4, and has a shape that covers the entire susceptor 153 b. The susceptor 153b is partially different from the susceptors 153 and 153a in accordance with the shape of the dielectric member 880.

  The upper surface portion of the susceptor 153b of the dielectric member 880 has a thickness t1, and if it is too thin, it is difficult to process, is inferior in durability, and a thick one is, for example, about 0.5 to 5 mm in consideration of cost. can do.

  A step t2 is provided on the upper surface of the dielectric member 880 that covers the outer peripheral portion of the susceptor 153b, and is configured so that the outer periphery of the wafer 1 can be guided and placed at an appropriate position. Since the thickness of the wafer 1 is about 0.7 mm, the step t <b> 2 is, for example, about 0.5 to 3 mm, preferably the same level as the wafer.

  In the plasma processing apparatus 150 equipped with such a semiconductor wafer mounting section 800, the wafer 1 is replaced with the processing that is conventionally performed using a dummy wafer for the initialization of the memory effect and the wet processing, or for the prevention of particle generation. The dielectric member 880 is etched without mounting.

  Etching conditions and required time are the same as in the first embodiment, but the dielectric member is simplified compared to the dielectric members according to the first, second, third and fourth embodiments. By adopting such a shape, replacement when consumed by etching is facilitated, the same effect can be obtained with a small amount of material, and it is more preferable when used in a plasma processing apparatus for mass production of semiconductor devices. Moreover, it is preferable to use Ar gas as a processing gas at the time of plasma processing for preventing particle generation.

  The preferred embodiments of the plasma processing apparatus and the initialization method thereof according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, the shape and material of the dielectric member are not limited to this example. Different shapes and materials may be used as long as the same effect can be obtained. Further, the processing conditions and processing time are specific to each plasma processing apparatus, and do not limit the present invention.

It is a general-view figure which shows the plasma processing apparatus concerning the 1st Embodiment of this invention. It is a schematic sectional drawing which shows the semiconductor wafer mounting part 100 concerning the 1st Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the bell jar 152 upper part. FIG. 4 is an enlarged view of a portion P in FIG. 3. FIG. 6 is a plan view of a connection part 223. It is a schematic sectional drawing of the gas introduction ring concerning the 1st Embodiment of this invention. It is a schematic sectional drawing of the gas introduction ring concerning another embodiment of this invention. It is a figure which shows the structure of 167d of gas passages. It is sectional drawing of the gasket concerning one embodiment of this invention. It is an elemental composition analysis figure by SEM-EDX (scanning electron microscope with an energy dispersive X-ray spectrometer). It is a conceptual diagram of particle generation. It is a figure which shows the fluctuation | variation of the etching amount by a memory effect. It is a figure which shows the fluctuation | variation of the etching amount by a memory effect. It is a schematic sectional drawing which shows the semiconductor wafer mounting part 500 concerning the 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the semiconductor wafer mounting part 600 concerning the 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the semiconductor wafer mounting part 700 concerning the 4th Embodiment of this invention. It is a schematic sectional drawing which shows the semiconductor wafer mounting part 800 concerning the 5th Embodiment of this invention. It is a schematic sectional drawing which shows an example of the semiconductor wafer mounting part 10 in the conventional plasma processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Semiconductor wafer mounting part 150 Plasma processing apparatus 153 Susceptor 180 Dielectric member

Claims (17)

A processing container for processing an object to be processed;
  A mounting table provided in the processing container and mounting the object to be processed;
  A gas introduction part for introducing a processing gas into the processing container;
  An antenna for generating plasma by exciting the processing gas in the processing container;
  A dielectric wall, and a seal member that hermetically seals the dielectric wall and the processing container,
  The plasma processing apparatus, wherein the sealing member is provided between a sealing surface of the dielectric and a sealing surface of the processing container, and protrusions are formed on the upper and lower surfaces of the sealing member. The plasma processing apparatus according to claim 1, wherein the processing container is formed in a bell jar shape. The plasma processing apparatus according to claim 1, wherein a high frequency power source is connected to the antenna. The plasma processing apparatus according to claim 1, wherein the antenna has a coil shape. The plasma processing apparatus according to claim 1, wherein the protrusion is formed in a semicircular mountain shape or a mountain shape. The plasma processing apparatus according to claim 1, wherein a plurality of the protrusions are formed. The plasma processing apparatus according to claim 1, wherein a metal cover is provided so as to cover the dielectric wall. The plasma processing apparatus according to claim 1, wherein a first electrode is disposed on the mounting table. The plasma processing apparatus according to claim 8, wherein a high frequency power source is connected to the first electrode. The plasma processing apparatus according to claim 8, wherein a second electrode is disposed so as to face the first electrode. The plasma processing apparatus according to claim 1, wherein the mounting table includes a heater. The plasma processing apparatus according to claim 1, wherein the seal member is a gasket. The plasma processing apparatus according to claim 12, wherein the gasket is made of a fluorine-based elastomer material. In a plasma processing apparatus configured to perform plasma processing on an object to be processed disposed in a processing chamber, a hole is formed between the side wall and the ceiling of the processing chamber toward the upper side of the processing chamber. A plasma processing apparatus comprising a gas introduction ring having a plurality of gas ejection holes. The plasma processing apparatus according to claim 14, wherein the gas ejection hole is formed in an upward tapered surface. The plasma processing apparatus according to claim 14, wherein the gas ejection hole is opened toward one point of the processing chamber. The plasma processing apparatus excites inductive plasma in the processing chamber through a bell jar type dielectric wall, and the ceiling portion is the bell jar type dielectric wall. The plasma processing apparatus according to any one of 15 and 16.

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