JP2009064863A - Plasma processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing device capable of improving processing efficiency by reducing contamination of a sample. <P>SOLUTION: This plasma processing device is provided with: a vacuum vessel; an antenna electrode supplying high-frequency energy to a processing gas supplied into the vacuum vessel to generate plasma; a sample base 101 arranged in the vacuum vessel, and sucking and holding a mounted processing object substrate; an exhaust pump 122 exhausting the processing gas supplied into the vacuum vessel through an exhaust opening arranged on the lower side of the sample base; a heat transfer gas supply pipe 202 supplying a heat transfer gas from a heat transfer gas source between the sample base and the processing object substrate mounted on the sample base through a supply valve; and a gas exhaust pipe 206 exhausting the heat transfer gas staying in the heat transfer gas supply pipe to the exhaust opening. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus, and more particularly, to a plasma processing apparatus for processing a sample by introducing a heat transfer gas between an upper surface of a sample table on which a sample is placed and a rear surface of the sample.

  The plasma processing apparatus includes a sample stage on which a sample is placed, and supplies a heat exchange medium to the inside of the sample stage to adjust the temperature of the sample stage to a predetermined range. In addition, a heat transfer gas such as He is supplied to the inside of the sample stage via a gas supply line, and this gas is supplied to the back side of the sample through an opening formed on the sample mounting surface on the upper side of the sample stage. To do. Thus, the temperature of the sample is adjusted by transferring heat supplied from the plasma or the like to the sample being processed to the sample stage.

During non-processing of the sample, the heat transfer gas accumulated in the gas supply pipe is discharged out of the processing chamber via an exhaust pipe communicating with the gas supply pipe, or the heat transfer gas Is discharged directly into the processing chamber. Patent document 1 is known as an example of such a prior art.
JP 60-116226 A

  In the above prior art, when the heat transfer gas is discharged during non-processing of the sample, the adhering matter adhering to the inner surface of the pipe constituting the exhaust path is peeled off along with the flow of the gas, and enters the processing chamber. The sample may fly and may adhere to the surface of the sample as a foreign substance and contaminate the sample. In such a case, the process yield decreases and the manufacturing cost increases.

  The present invention has been made in view of such problems, and provides a plasma processing apparatus capable of reducing the contamination of a sample and improving the processing efficiency.

  In order to solve the above problems, the present invention employs the following means.

  A vacuum vessel, an antenna electrode for generating plasma by supplying high-frequency energy to a processing gas supplied into the vacuum vessel, and a sample stage for adsorbing and holding a substrate to be processed that is placed in the vacuum vessel, and An exhaust pump for exhausting the processing gas supplied into the vacuum vessel through an exhaust port disposed below the sample stage, and a heat transfer gas from a heat transfer gas source via the supply valve to the sample stage. A heat transfer gas supply pipe for supplying between the substrates to be processed placed on the sample stage and a gas discharge pipe for discharging the heat transfer gas staying in the heat transfer gas supply pipe to the exhaust port are provided.

  Since the present invention has the above-described configuration, it is possible to reduce the contamination of the sample and improve the processing efficiency.

  Hereinafter, the best embodiment will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a plasma processing apparatus according to the present embodiment. In FIG. 1, a vacuum vessel 130 constituting a plasma processing apparatus is a vessel including a processing chamber that is a space in which a sample such as a semiconductor wafer is placed under reduced pressure and plasma is formed. The vacuum vessel 130 is connected to a transfer vessel (not shown) which is a vacuum vessel connected to the side wall of the vacuum vessel 130 and serves as a transfer chamber in which a sample is transferred. The processing chamber and the transfer chamber are communicated with each other by an opening arranged between them and the sample is transferred, and an atmospheric gate valve 125 that opens and closes the opening is arranged between the transfer chamber and the processing chamber. Has been.

  The opening of the atmospheric gate valve 125 is opened and closed by its vertical and horizontal movements, and the space of the transfer chamber and the space of the processing chamber are communicated with each other in the opened state. The effect on sample transport and processing is negligible. When the atmospheric gate valve 125 is opened, the sample is carried from the transfer chamber to the sample mounting surface on the upper surface of the sample table 101 disposed in the processing chamber. Conversely, the sample on the sample stage 101 in the processing chamber passes through the opening and is carried out into the transfer chamber.

  When a detection device such as a sensor (not shown) detects that the sample has been placed on the sample table 101, the atmospheric gate valve 125 operates to close the opening and seal the inside of the processing chamber to start processing the sample. . The sample placed on the sample stage 101 is held on the sample stage 101 by an electrostatic adsorption force generated by supplying power from a DC power source to the electrodes arranged in the sample stage 101. In this state, a heat transfer gas such as He is introduced into the space between the sample and the upper surface of the sample table 101.

  As shown in FIG. 1, the upper portion of the vacuum chamber 130 constituting the processing chamber is a discharge chamber 110, and the lower portion communicates with the discharge chamber 110 and gas and particles in the discharge chamber 110 move and are exhausted. A vacuum chamber 131 is provided. The vacuum chamber 131 and the discharge chamber 110 constitute a processing chamber. An exhaust device including an exhaust pump 122 and an auxiliary pump 127 connected to the bottom surface of the vacuum vessel 130 is connected to the lower side of the vacuum vessel 130.

  The discharge chamber 110 includes a lid member 106 constituting a lid of the vacuum vessel 130, an antenna member disposed inside the lid member 106, and is disposed on the side and upper side of the antenna member so as to surround the discharge chamber 110. A magnetic field generation unit and a ceiling member disposed below the antenna member are included. Further, a radio wave source unit 108 for generating a radio wave in the UHF band or VHF band emitted from the antenna member is disposed above the magnetic field generation unit.

  The antenna member is a disk-shaped antenna 104 disposed inside a lid member 106 made of a conductive member such as SUS, and is disposed between the antenna 104 and the lid member 106 to insulate them. In addition, at least one dielectric 105 having a substantially ring shape is disposed to conduct radio waves emitted from the antenna 104 to the lower ceiling member side. The magnetic field generator includes a solenoid coil 107 surrounding the antenna 104 and the dielectric 105 in a ring shape, and the magnetic field generated by the solenoid coil 107 is supplied into the discharge chamber 110.

  Further, the ceiling member 103 is provided with a quartz plate 103 made of a dielectric material such as quartz in order to conduct the transmitted radio wave to the lower processing chamber side, and the processing supplied by being disposed below the quartz plate 103. The shower plate 102 is formed with a plurality of through holes for dispersing and introducing the process gas into the processing chamber. The space below the shower plate 102 and above the sample stage 101 is an interaction between the radio wave introduced into the supplied process gas through the quartz plate 103 and the magnetic field supplied from the magnetic field generator. Thus, a discharge chamber 110 is formed in which plasma is formed.

  Processing of the sample placed on the sample stage 101 is performed by the plasma formed in the discharge chamber 110. Further, a space formed with a minute gap is disposed between the quartz plate 103 and the shower plate 102, and a process gas supplied to the discharge chamber 1110 is first introduced into the space, and the space in the space is introduced. To spread. Further, the process gas flows into the discharge chamber 110 through the through-hole, which is disposed on the shower plate 102 and communicates the space and the discharge chamber 110. The space is a buffer chamber 109 disposed so that the process gas is dispersed from the plurality of through holes and flows into the discharge chamber 110.

  A lower ring 111 is disposed below the lid member 106 on the outer peripheral side of the quartz plate 103 and the shower plate 102, and a gas line through which the process gas flows into the buffer chamber 109 is disposed inside the lower ring 111. A gas passage (not shown) that communicates is disposed. A discharge chamber side wall member 120 surrounding the discharge chamber 110 is disposed below the lower ring 111. The discharge chamber side wall member 120 is connected to discharge chamber base plates 112 and 113 that constitute a vacuum vessel and support the discharge chamber portion from below to constitute a vacuum vessel 130.

  The vacuum vessel of this embodiment includes a discharge chamber 110 in which plasma is formed. Moreover, it has the inner chambers 114 and 115 surrounding the vacuum chamber 131 formed under the discharge chamber 110, and the outer chambers 116 and 117 surrounding from the outside of the inner chamber. That is, below the discharge chamber base plates 112 and 113, a vacuum chamber base plate 119 and an inner chamber 114 that are in contact with the lower surfaces thereof are arranged. Further, an external force due to the atmospheric pressure applied to the quartz plate 103 transmitted through the discharge chamber side wall member 120 is transmitted to the vacuum chamber base plate 119 and the inner chamber 114.

  Further, the external force transmitted by the atmospheric pressure transmitted to the vacuum chamber base plate 119 is transmitted from the upper outer chamber 116 connected to the lower side to the lower outer chamber 117, and is arranged between these members by the transmitted external force. By deforming the sealing member made of an elastic body, the space between the outer chambers 116 and 117 and the atmosphere outside thereof is sealed, and the internal vacuum is maintained. A space is arranged between the inner chamber 114 and the outer chambers 116 and 117. The space is sealed between the space inside the inner chambers 114 and 115 (processing chamber), and the internal gas and particles are prevented from flowing into the space between the outer chambers 116 and 117. Has been.

  In order to place a sample such as a semiconductor wafer to be processed on the placement surface of the sample stage 101 in the inner chambers 114 and 115, a gate having an opening for carrying the sample into the inner chambers 114 and 115 is provided. Necessary. Further, a valve is required that opens or closes the gate to communicate and block the space inside and outside the chamber.

  In the present embodiment, as such a valve, an atmospheric gate valve 125 which is disposed between the inner space of the processing chamber and the inner space of the transfer chamber, and communicates or blocks them, and the inner and outer sides of the inner chamber 114, Is provided with a process gate valve 124 for communicating or blocking.

  The atmospheric gate valve 125 is disposed on the inner side wall of the transfer chamber and is configured to be movable in the vertical direction or the horizontal direction. The atmospheric gate valve 125 closes or opens to seal the gate on the inner sidewall. Further, the process gate valve 124 has a gate disposed at a position where it communicates with the gate on the transfer chamber side when the transfer chamber and the processing chamber communicate with the outer chamber 116 constituting the vacuum vessel.

  The process gate valve 124 is disposed in a space between the outer chamber 116 and the inner chamber 114, and is configured to be movable in the vertical direction and the horizontal direction. When closed, the process gate valve 124 is interposed between the outer side wall of the inner chamber 114 and the vacuum vessel. In place, the inner chamber 114 is sealed.

  When processing a sample, a disk-shaped lid 121 that is disposed immediately below the substantially cylindrical sample stage 101 and closes and opens the substantially circular exhaust port 126 disposed at the bottom of the space in the processing chamber is directed upward. The exhaust port 126 is opened by moving. Next, in this state, the rotation angle of the variable valve 123 that adjusts the flow passage area of the opening by adjusting the rotation of the flow passage area of the opening provided with a plurality of plates arranged in the exhaust port 126 and rotatable around the rotation axis in the same direction is adjusted. The exhaust pump 122 such as a turbo molecular pump and the auxiliary pump 127 connected to the downstream side are driven while adjusting the amount of exhaust. As a result, the inside of the processing chamber is evacuated and a high degree of vacuum is maintained.

  Next, high frequency power is supplied from the high frequency power source 129 to the conductive member inside the sample stage 101. As a result, a predetermined bias potential is formed on the sample surface, and the overcharged particles in the plasma formed in the space of the discharge chamber 110 above the sample are attracted to the surface of the sample, so that the sample surface has a predetermined shape. Processed.

  Note that the radio wave source unit 108, the solenoid coil 107, the variable valve 123, the exhaust device including the exhaust pump 122, the process gate valve 124, the atmospheric gate valve 125, and the like receive the outputs from the detection devices disposed therein. Based on the received result, adjustment is made by a control device 128 that transmits an operation command. This control device has at least one arithmetic device, and includes a storage device that stores the received result or a program of predetermined operations and arithmetic operations. The control device can be provided in the vicinity of the plasma processing apparatus. Moreover, it can arrange | position in another location which can communicate via a communication means.

  FIG. 2 is a diagram for explaining details in the vicinity of the processing chamber. As shown in FIG. 2, by supplying power from the DC power source 129 to the upper electrode 201 disposed on the upper part of the sample stage 101, the dielectric film constituting the mounting surface on the upper surface of the sample stage 101 is caused by static electricity. An attracting force is generated, whereby the sample placed on the dielectric film is attracted and held on the sample stage 101.

  During sample processing, for example, etching processing, the sample is heated by the heat from the plasma. Therefore, it is necessary to cool the sample in order to adjust the temperature of the sample to an appropriate value. Therefore, a coolant is circulated through the sample table 101 to adjust the temperature of the sample table 101 to a predetermined range, and heat is transferred between the back surface of the sample and the surface of the dielectric film of the sample table 101. Gas is introduced to promote heat transfer from the sample to the sample stage 101.

  In order to improve the cooling by the heat transfer gas, an introduction path for the heat transfer gas reaching the dielectric film is arranged inside the sample stage 101, and a gas supply pipe 202 is arranged at the lower end side of the introduction path. ing. The introduction path of the heat transfer gas is a path for supplying the heat transfer gas between the sample mounting surface and the sample back surface during sample processing, and the plasma processing apparatus is not processing, for example, processing of one sample is performed. It is also a path for discharging the heat transfer gas into the processing chamber from the end to the start of processing on the next sample. Switching between the introduction and the exhaust is performed by switching the valves 203 and 204 according to a command from the control device 206.

  FIG. 3 is a diagram for explaining the flow of processing in the plasma processing apparatus shown in FIG. In FIG. 2, when the plasma processing apparatus is not performing processing (not processing), the valve 203 is closed and the valve 204 is set to an open state. Thus, the heat transfer gas introduced from the gas source and staying in the gas supply pipe 202 is discharged out of the processing chamber through the gas discharge pipe 206 and the nozzle 205.

  The jet outlet, which is the tip of the nozzle 205, faces the space below the sample stage 101 in the processing chamber and above the exhaust port 126 of the processing chamber just below the sample stage 101, and the inner wall surface of the inner chamber 117. Located on the top. Furthermore, the nozzle 205 has a jet outlet disposed at the tip of the nozzle 205 so that the flowing heat transfer gas flows toward the space between the exhaust port 126 and the lid 121 that opens and closes the exhaust port 126.

  The ejected heat transfer gas diffuses in the space above the exhaust port 126 and below the sample stage 101, moves toward the inlet of the exhaust pump 122, and is discharged out of the processing chamber. By discharging the heat transfer gas toward the upper side of the exhaust port 126, the heat transfer gas is dispersed toward the narrow portion on the outer peripheral side of the sample stage or the discharge chamber 110, and the nozzle 205 or the processing chamber in the vicinity thereof. The product released from the wall is prevented from moving in the direction of the sample, thereby reducing the generation of foreign matter.

  When starting the processing of the sample, DC power is supplied from the ESC power source 103 to the electrode 201 in the sample table 101 while the sample is placed on the sample table 101, and the sample is adsorbed on the sample table 101. Then, the valve 203 is opened and the valve 204 is closed, and the heat transfer gas is introduced into the space between the sample and the upper surface of the sample stage 101. At this time, the pressure in the space between the sample and the sample stage 101 is adjusted by adjusting the pressure or flow rate of the heat transfer gas. In this state, a process gas is introduced into the processing chamber and sample processing is started.

  After the processing of the sample is completed, the valve 203 is closed and the valve 204 is opened to stop the supply of the heat transfer gas to the space between the back surface of the sample and the top surface of the sample table 101, and the gas discharge pipe 206 and the nozzle It is discharged out of the processing chamber via 205.

  As described above, in the prior art, when the heat transfer gas is exhausted, the heat transfer gas is provided with a discharge path that communicates with the heat transfer gas exhaust pipe or the exhaust pipe facing the space in the processing chamber. Was discharged through. For this reason, the adhering matter adhering to the wall surface in the exhaust pipe or the exhaust passage is peeled off by the gas flow and flies into the processing chamber, adheres to the surface of the sample on the sample stage 101, and becomes a foreign matter. There has been a problem that

  Further, the heat transfer gas introduced into the back surface of the sample is supplied at a pressure higher than the pressure in the processing chamber in order to improve heat transfer. For this reason, when the plasma processing apparatus is stopped due to a power failure or the like, the sample receiving the force from the high-pressure heat transfer gas may be displaced or dropped from the sample stage 101 when the processing chamber is sealed.

  In order to suppress this, even when the stop occurs, it is necessary to make the pressure on the upper surface and the back surface of the sample substantially equal or to increase the pressure on the upper surface.

  In the present embodiment, the gas discharge pipe constituting the path for discharging the heat transfer gas communicates the back surface of the sample and the processing chamber via the gas supply pipe. For this reason, the heat transfer gas on the back side of the sample can be discharged to the exhaust port 126 that opens directly below the processing chamber via the gas supply pipe, the gas discharge pipe, and the nozzle.

  By the way, if the opening of the discharge path of the heat transfer gas faces the processing chamber, deposits contained in the exhausted heat transfer gas accumulate in the path, and as a result, the deposit flies into the processing chamber. Will do. In particular, when the opening is located above the sample stage 101, foreign matters are likely to adhere to the sample. Below the discharge chamber 110, there is a narrow portion in which the outer peripheral surface of the sample stage 101 and the inner peripheral surface of the inner chamber 114 are close to each other, and the space between them is smaller than the upper and lower spaces. When the discharge path is arranged so as to face the portion, the peeled deposit adheres to the outer peripheral side wall of the sample stage 101, and this deposits on the discharge chamber 110 due to the flow of the gas being processed and the interaction with the plasma. May fly and cause sample contamination.

  In this embodiment, the sample stage 101 is supported in alignment with the axis of the inner chamber 114 by a plurality of support beams arranged symmetrically with respect to the central axis and extending to the outer peripheral side, and below the narrow portion A wide space is arranged. An exhaust port 126 for exhausting the inside of the processing chamber is disposed at the bottom of the widened space, and the nozzle 205 constituting the heat transfer gas exhaust path is a widened exhaust port 126 below the sample stage 101. Facing. In the example shown in FIG. 2, a vertically movable lid 121 that opens and closes the exhaust port 124 is provided in a space below the sample stage 101 in the processing chamber.

  The nozzle 205 constituting the discharge path of the heat transfer gas is disposed so that the opening faces the exhaust port 126 below the lid 121, and discharges the heat transfer gas below the lid 121. The discharged heat transfer gas is sucked and discharged through the exhaust pump 122.

  The exhaust port 126 disposed at the tip of the nozzle 205 is opened between the lid 121 that has moved upward and the exhaust port 126 covered by the lid 121, and the heat transfer gas discharged from the exhaust port. Diffuses in the space below the sample stage 101, below the lid 121 and above the opening. With this configuration, when the heat transfer gas is discharged through the discharge path, it is possible to easily discharge the deposits that have separated from the discharge path and the like along with the discharge to the outside of the processing chamber. It can suppress that a foreign material adheres to the surface.

  In the example of FIG. 2, the temperature of the outer chamber 117 is adjusted by a heater (not shown) or a circulating supply of refrigerant. The nozzle 205 is inserted from the lower part of the outer chamber 117 so as to penetrate the outer chamber 117 and the inner chamber 115 so that the tip of the nozzle 205 protrudes into the processing chamber. Further, the metal nozzle 205 having a high heat transfer property is adjusted to substantially the same temperature as the outer chamber 117. A discharge pipe including a gas discharge pipe 206 and a gas supply pipe 202 connected to the nozzle 205 is covered with a heat insulating material to maintain the temperature, and these discharge pipes are means for adjusting the temperature of the outer chamber 117. The temperature is maintained at a predetermined temperature by using the temperature control.

It is a figure explaining the plasma processing apparatus concerning an embodiment. It is a figure explaining the detail of a process chamber vicinity. It is a figure explaining the flow of a process in a plasma processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Sample stand 102 Shower plate 103 Quartz plate 104 Antenna electrode 105 Dielectric body 106 Cover member 107 Magnetic field generation part 108 Radio wave source part 109 Buffer room 110 Discharge room 111 Lower ring 112,113,119 Discharge room base plate 114,115 Inner chamber 116, 117 Outer chamber 120 Discharge chamber side wall member 121 Lid 122 Exhaust pump 124 Process gate valve 125 Atmospheric gate valve 126 Exhaust port
127 Auxiliary pump 201 Electrode 202 Gas supply pipe 205 Nozzle 206 Gas discharge pipe

Claims (4)

A vacuum vessel;
An antenna electrode for generating plasma by supplying high-frequency energy to the processing gas supplied into the vacuum vessel;
A sample stage for adsorbing and holding a substrate to be processed disposed and placed in the vacuum vessel;
An exhaust pump for exhausting the processing gas supplied into the vacuum vessel through an exhaust port disposed below the sample stage;
A heat transfer gas supply pipe for supplying a heat transfer gas from a heat transfer gas source between the sample stage and a substrate to be processed placed on the sample stage via a supply valve;
A plasma processing apparatus comprising a gas discharge pipe for discharging a heat transfer gas staying in the heat transfer gas supply pipe to the exhaust port. The plasma processing apparatus according to claim 1,
The plasma processing apparatus, wherein the exhaust port includes a lid member that moves up and down above the exhaust port to open and close the exhaust port. The plasma processing apparatus according to claim 1,
The vacuum vessel is provided with a narrow portion between an inner wall of the vacuum vessel and a sample stage, and the gas exhaust pipe for discharging the heat transfer gas has an opening portion that opens to the exhaust pump side than the narrow portion. A plasma processing apparatus. A vacuum vessel;
An antenna electrode for generating plasma by supplying high-frequency energy to the processing gas supplied into the vacuum vessel;
A sample stage for adsorbing and holding a substrate to be processed disposed and placed in the vacuum vessel;
An exhaust pump for exhausting the processing gas supplied into the vacuum vessel through an exhaust port disposed below the sample stage;
A heat transfer gas supply pipe for supplying a heat transfer gas from a heat transfer gas source between the sample stage and a substrate to be processed placed on the sample stage via a supply valve;
A nozzle having a jet opening at the exhaust port;
A plasma processing apparatus, wherein heat transfer gas staying in the heat transfer gas supply pipe is discharged to the exhaust port through the nozzle.

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