JP2008112912A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus that reduces pollution caused by suppression of foreign matters that are produced from a wall material of a processing chamber, contributes to the uniformity of plasma distribution, and does not require precise management of the processing chamber. <P>SOLUTION: The plasma processing apparatus uses plasma generated in the processing chamber 100 to process a sample placed on a sample stage 109 that is disposed inside the processing chamber 100. In the plasma processing apparatus, the processing chamber 100 is constituted of an inner wall member with a conic inner shape, which is separated into two parts, an upper inner wall member 116 and a lower inner wall member 124. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus applied to microfabrication such as a semiconductor manufacturing process, and more particularly to a plasma processing apparatus capable of reducing the occurrence of foreign matter and contamination by foreign matter by suppressing the shaving of a chamber inner wall.

  Conventionally, plasma processing apparatuses such as plasma CVD and plasma etching apparatuses have been widely used as semiconductor manufacturing apparatuses for manufacturing semiconductor devices by processing workpieces such as silicon wafers (hereinafter referred to as wafers). As device integration increases, circuit patterns continue to become finer, and as a result, the accuracy of processing dimensions required for these plasma processing apparatuses is becoming increasingly severe. Moreover, in recent years, the constituent materials of devices have also diversified, and the etching recipe has become complicated accordingly. As a result, stabilization of long-term mass production has become an important issue.

  For example, in the case of a plasma processing apparatus, a reactive gas plasma such as fluoride, chloride, or bromide is used, so that the processing chamber wall surface is chemically and physically eroded, and as the number of wafers processed increases. The chance of reaction products adhering to the processing chamber wall increases, foreign matter is generated, the inner wall of the chamber is scraped, and the life of the parts is shortened. As a result, long-term stable processing becomes difficult. There is a risk that.

Therefore, in order to cope with such a problem, in a certain prior art, the side wall of the plasma generation chamber is inclined, thereby reducing the incident angle at which the charged particles enter the wall surface, and contamination by foreign matter from the wall material. A system that can reduce the occurrence has been proposed (see, for example, Patent Documents 1 and 2).
JP-A-7-94297 JP-A-8-138890

  In the above prior art, since the plasma generation region has a conical shape and the processing chamber has a cylindrical shape, the plasma density is reduced in the cylindrical processing chamber, and the gas flow tends to be stagnation, so that the deposit on the wall surface is reduced. (Foreign matter accumulation) is likely to occur, and the interaction between the plasma and the processing chamber wall surface is likely to be uneven, such as etching recycling. In this case, there is a possibility of contamination due to foreign matter. Further, in the case where the processing chamber has a cylindrical side wall as described above, radicals are easily adsorbed on the wall, which may affect the uniformity of the etching rate and CD distribution.

  Moreover, in recent years, the requirement for contamination of impurities such as heavy metals on the wafer to be processed has become strict, and alumina, which is a plasma resistant material, aluminum, which is a main element of anodized, yttrium, which is a main component of yttria, iron (Fe ), Inclusion of trace amounts of metals such as magnesium (Mg) is no longer negligible. Therefore, it is also necessary to suppress the consumption of such a plasma-resistant member, but it is difficult to meet such a demand with the conventional technology.

  In addition, in the prior art, it cannot be said that consideration is given to the configuration for controlling the temperature of the inner wall of the chamber. For this reason, for example, the surface temperature of the wall surface may be partially different depending on the structure of the inner wall surface. For this reason, when a gas having a high adhesion coefficient is used, there is a possibility that the gas adheres to the wall surface at a low temperature and the distribution of the etching gas on the wafer is biased.

  In addition, it is necessary to raise the temperature of the inner wall surface, so that the thermal expansion on the inner wall increases, and it is necessary to provide a gap in consideration of the thermal expansion between the respective wall surfaces. If there is, there is a possibility that the state of the plasma will be different between apparatuses. Therefore, in the prior art, strict dimensional control is required in the processing chamber.

  The present invention has been made in view of the above circumstances, and its purpose is to reduce the occurrence of contamination due to the suppression of foreign matter generated from the wall material of the processing chamber, contribute to the uniformity of plasma distribution, and It is an object of the present invention to provide a plasma processing apparatus that requires less dimensional control.

  The object is to have a sample stage in a processing chamber consisting of a vacuum vessel, to form a plasma in the space above the sample stage by applying an electromagnetic wave and applying a magnetic field, and to place a wafer placed on the sample stage with the plasma. In the plasma processing apparatus to be processed, a conical inner wall member is provided in which the wall surface facing the plasma above the wafer in the processing chamber is inclined downwardly toward the bottom along the isomagnetic surface of the magnetic field, This is achieved by the inner wall member being composed of two ring-shaped members that are divided into two vertically.

  According to the present invention, since the inner wall member is composed of two ring-shaped members that are divided into two vertically, strict dimensional control is possible even when a gap is provided in consideration of thermal expansion between the members. As a result, it is possible to suppress the apparatus difference and to reduce the cost.

  In addition, according to the present invention, since the processing chamber serving as the plasma generation region has a conical shape, the generation of foreign matters from the wall material and the occurrence of contamination are reduced. Since the interaction between the plasma and the processing chamber wall surface is made uniform, the uniformity of the etching rate and CD distribution can be improved.

  Hereinafter, a plasma processing apparatus according to the present invention will be described in detail with reference to an illustrated embodiment. First, FIG. 1 is a longitudinal sectional view showing a processing chamber (processing chamber) in the embodiment of the present invention as 100. In this case, as shown in the drawing, this processing chamber 100 is located in the middle of the upper lid member 101. A vacuum chamber is formed by an inner chamber 121 and an inner chamber 122 provided thereunder via a support base member 129, and a sample stage 109 is provided inside by a support beam 128, and a workpiece is provided on the sample stage 109. A wafer is placed and plasma treatment is performed on it. At this time, an outer chamber 119 is provided outside the inner chamber 121, and an outer chamber 120 is provided around the inner chamber 122 at the lower portion. A vacuum chamber 123 is formed in the inner chamber 122. The sample stage 109 is provided with a dielectric film 135 and an electrode cover 136.

  First, the lid member 101 constituting the lid of the vacuum vessel is provided with a discharge chamber portion including an antenna 102 disposed on the inside thereof and a ceiling member disposed below the antenna 102. . A magnetic field generation unit 103 is provided so as to surround the discharge chamber portion and on both the side and the upper side of the antenna 102. Above the magnetic field generation unit 103, a 200 MHz VHF band to a 1 GHz UHF band are provided. A high frequency power source unit 105 for supplying high frequency power to the antenna 102 is disposed in order to radiate radio waves (electromagnetic waves) of frequencies up to.

  At this time, the antenna 102 is disposed inside a lid member 101 made of a conductive member such as SUS. The lid member 101 and the antenna 102 are insulated from each other and radiated from the antenna 102. The dielectric member 106 is arranged to conduct the radio wave transmitted to the lower ceiling member side, and this ceiling member includes quartz or the like for conducting the radio wave transmitted from the antenna 102 to the lower processing chamber side. A quartz plate 107 made of a dielectric material and a processing gas disposed under the quartz plate 107 and supplied from the outside via the process gas line 112 are dispersedly introduced into the inside of the processing chamber. A shower plate 108 in which a plurality of holes are formed is provided.

  A space formed below the shower plate 108 and above the sample stage 109 is a discharge chamber 110, and the process gas introduced through the shower plate 108 is supplied from the antenna 102 to the process gas. The radio wave interacts with the magnetic field supplied from the magnetic field generator 103, whereby plasma is formed in the discharge chamber 110. For this reason, a minute space is formed between the quartz plate 107 and the shower plate 108, and the process gas is first supplied from the process gas line 112 to the space and discharged through the hole of the shower plate 108. It flows into the chamber 110.

  At this time, the above-described space constitutes a buffer chamber 111 through which process gas is dispersed from the plurality of holes of the shower plate 108 and flows into the discharge chamber 110. At this time, the process gas is supplied into the processing chamber from the controller 114 that adjusts the flow rate via the process gas line 112 and the process gas cutoff valve 113. At this time, in this embodiment, after the process gas is dispersed and introduced into the discharge chamber 110 from a plurality of holes, the sample is placed on the sample stage 109 mainly through these holes. In addition to the function of the buffer chamber 111 that can disperse the process gas in a more uniform manner, the plasma density is further made uniform. become.

  A lower ring 115 is disposed below the lid member 101 on the outer peripheral side of the quartz plate 107 and the shower plate 108. In the lower ring 115, a gas passage communicating with the gas line 112 is provided to allow the process gas to flow into the buffer chamber 111. On the other hand, below the shower plate 108, ring-shaped inner wall members 116 and 124 that partition the space of the discharge chamber 110 facing the plasma inside the vacuum vessel are provided. At this time, a discharge chamber outer wall member 117 disposed so as to surround the inner wall member 116 is provided on the outer peripheral side of the inner wall member 116, and the outer wall surface of the inner wall member 116 and the inner wall surface of the outer wall member 117 of the discharge chamber. Are in contact with each other.

  Here, in this embodiment, in order to generate plasma stably, as will be described in detail later, the inner wall member in the region where the plasma is generated is inclined along the direction in which the magnetic field generator 103 forms the lines of magnetic force. In the upper portion, a substantially cylindrical inner wall member 116 slightly extending downward is formed, and the lower portion is configured by a conical inner wall member 124 extending downward. Then, the heater 140 is wound around the outer peripheral surface of the outer wall member 117, and thereby the temperature of the outer wall member 117 is adjusted, so that the wall surface temperature of the inner wall member 116 in contact therewith can be controlled. It is. At this time, the heater 140 is provided with a heater cover 142.

  By the way, when the inner wall member 116 is conical (tapered) in this way, it is more efficient to make the outer wall member 117 conical as well in order to effectively expand the diameter of the processing chamber. However, in this case, the more gently the wall is inclined, the more difficult the heater 140 is fixed. And when the heater 140 is not contacting firmly, a heater may burn out. Therefore, in order to improve the contact between the heater 140 and the outer wall member 117 and efficiently transfer heat, the outer peripheral side of the outer wall member 117 to which the heater 140 is attached is formed in a cylindrical shape as shown in the figure. In addition, a discharge chamber base plate 118 is disposed on the outer peripheral side of the outer wall member 117 in contact with the lower surface of the outer wall member 117. A space is provided in the base plate 118, and a heat exchange medium 141 is provided therein. It is designed to be circulated.

  By the way, normally, the inner wall member in the plasma generation region is attached from the inner side to the lower side of the outer wall member 117. However, in this case, since the member becomes large, the dimensions of the inner wall member greatly change due to thermal expansion. Along with this, the gap between the shower plate 108 and the inner wall member changes greatly, and the plasma may change due to the difference in dimensions. This can be improved by tightening the dimensional tolerance, but in that case, as described above, the cost is affected. Therefore, in order to improve this, the structure in which the inner wall member is divided into two parts as in this embodiment is more effective in terms of maintenance and dimensional tolerance.

  Therefore, in this embodiment, first, the hinge 143 is disposed on the base plate 118, and the outer wall member 117 is attached to the base plate 118. Then, the outer wall member 117 is used as a base, and the inner wall member 116 and the inner wall member 124 are installed from the upper side and the lower side thereof. Handling becomes easy. Further, when the inner wall member 116 expands, the inner wall member 116 is located above the outer wall member 117, so that it can extend in the vertical direction with the installation surface as a boundary. It is possible to prevent the gap 116 from being affected by thermal expansion.

  Therefore, according to this embodiment, the influence on the plasma due to the difference in the gap between the shower plate 108 and the inner wall member 116 is reduced, and the number of members whose size is strictly controlled is reduced. Costs can be suppressed between apparatuses, and a cost difference between apparatuses can be suppressed.

  Next, the inner chamber 121 in the middle will be described. Here, the sample stage 109 is provided, and a lower inner chamber 122 is disposed below the block. The central portion of the inner chamber 122 is provided with an opening through which the gas in the inner chamber 121 flowing around the sample stage 109 flows. The exhaust pump 132 is communicated. At this time, the exhaust valve 131 includes a plurality of plate-shaped shutters that are configured to allow communication between the space inside the inner chamber 122 and the exhaust pump 132, or to block the shutter. By moving it, the exhaust passage area is adjusted to adjust the exhaust flow rate and speed.

  Therefore, in this embodiment, the exhaust means is disposed below the sample stage 109, particularly directly below. As a result, the plasma and processing in the space above the sample stage 109 in the inner chamber 121 are processed. Gases and reaction products are exhausted through a short exhaust path extending from the periphery of the sample stage 109 to the exhaust valve 131 via the space in the lower inner chamber 122. As a result, the gas and reaction products are effectively removed in a short time. Exhaust processing becomes possible.

  More specifically, in FIG. 2, first, a semiconductor wafer W, which is an object to be processed, is loaded into the processing chamber 100 from a transfer unit (not shown), and then is placed on the electrostatic adsorption electrode 134 of the sample stage 109. And electrostatically attracted by a DC high voltage applied from a high voltage power source 137. Next, a gas necessary for the etching process of the semiconductor wafer W, for example, a halogen-based gas is supplied from the process gas line 112 into the processing chamber 100 at a predetermined flow rate while maintaining a predetermined mixing ratio. At this time, the inside of the processing chamber 100 is adjusted to a predetermined processing pressure by the exhaust pump 132 and the exhaust valve 131.

  By the way, in such an etching processing apparatus, the process gas introduced into the processing chamber is efficiently turned into plasma by the interaction between the high-frequency electric field and the magnetic field of the magnetic field coil. In this etching process, the incident energy of ions in the plasma incident on the wafer is controlled by a high frequency bias so that a desired etching shape can be obtained.

  Therefore, high frequency power is supplied from the high frequency power source unit 105 to the antenna 102 so that electromagnetic waves are radiated from the antenna 102. Then, the electromagnetic wave interacts with a substantially horizontal magnetic field formed inside the processing chamber 100 by the magnetic field generator 103, and the plasma P is efficiently generated in the processing chamber 100. Then, the generation of the plasma P dissociates the process gas and generates ions and radicals. At this time, the bias power is supplied from the bias power source 138 to the electrostatic chucking electrode 134 via the matching circuit 139, thereby performing etching while controlling the temperature of the semiconductor wafer W.

  Here, in the plasma processing apparatus according to this embodiment, magnetic field lines 201 as shown in FIG. Therefore, high-density plasma is generated immediately below the shower plate 108 by the high frequency and the magnetic force lines 201 applied from the antenna 102. Further, since the plasma P generated at this time is constrained by the magnetic lines of force 201, the plasma density on the surface of the inner wall member 116 covered with the plasma-resistant material on the extension of the magnetic lines of force 201 is increased. As a result, Effective etching can be obtained.

  Moreover, at this time, in this embodiment, as shown in the figure, the wall surfaces of the inner wall members 116 and 124 are formed so as to be substantially parallel to the magnetic force lines 201. Specifically, as described above, the wall surface is inclined along the direction in which the magnetic field generator 103 forms the magnetic lines of force, and the upper portion is formed as a substantially cylindrical inner wall member 116 that slightly extends downward. The portion is composed of an inner wall member 124 having a conical shape that extends downward. As a result, the angle at which the charged particles are incident on the inner wall is reduced. As a result, the sputtering action acting on the wall surface is suppressed, and therefore the wall surface can be prevented from being scraped.

  Next, temperature control of the wall member according to this embodiment will be described. Here, first, how heat is transferred by the heater 140 and the heat exchange medium 141 will be described with reference to FIG. In this case, since the heater 140 is in contact with the outer wall member 117, heat is transferred through the outer wall member 117 as shown by a solid line. At this time, since the outer wall member 117 and the inner wall member 116 are in contact with each other particularly at the upper part, heat is transferred from the upper side. Further, since the outer wall member 117 is also in contact with the lower inner wall member 124, heat is transferred to the inner wall member 124. Here, the outer wall member 117 is also in contact with the base plate 118, but in this case, since the member is separated from the heater 140 and the member has a thin structure, it is difficult for heat to be transmitted, and thus the temperature of the base plate 118 is low. ing.

  On the other hand, the heat exchange by the heat exchange medium 141 is because the heat exchange medium 141 flows in the base plate 118, so that the heat is first transferred to the inner wall member 124, the inner wall member 124 is cooled, and further below it. The inner chamber 121 on the side is cooled. Here, the inner wall member 124 can take in heat from the heater 140 and heat from the heat exchange medium 141, and as a result, by adjusting the temperature of the heater 140 and the temperature of the heat exchange medium 141. Temperature control is possible.

  Therefore, according to this embodiment, the inner wall member 116, the inner wall member 124, and the inner chamber 121 can be controlled to different temperatures, and their surface, plasma, particles contained therein, gas, reaction generation The interaction between the objects is controlled, and as a result, it is possible to adjust the etchant and deposit that contribute to the wafer, and to improve the uniformity of the etching rate and CD distribution.

  By the way, in the above embodiment, the inner wall member is divided into the inner wall member 116 and the inner wall member 124. However, from the viewpoint of ease of maintenance, the inner wall member may be integrated. Conceivable. In this case, since the inner wall member has a conical shape, it is necessary to fit the outer wall member 117 from below the outer wall member 117. At this time, the outer wall member 117 has a heater cable. Is difficult to remove. Therefore, in this case, it is preferable to make the outer wall member 117 movable by power.

  As a reference example, FIG. 4 shows a case where the magnetic field generator 103 is installed on the movable member 401 and can be moved up and down by a motor. In this case, the clip 402 is attached to the movable member 401. 5 is an example in which the outer wall member 117 can be lifted and removed from the integral inner wall member 403 by engaging the base plate 118 with the base plate 118. FIG. An example in which the outer wall member 117 is lifted and removed from the integrated inner wall member 403 by being attached to the outer wall member 403 and then rotated around the movable member 501 so that the inner wall member 403 can be taken out from the side. It is.

It is a longitudinal cross-sectional view which shows one Embodiment of the plasma processing apparatus which concerns on this invention. It is sectional drawing which expanded and showed a part of embodiment of this invention. It is a partially expanded sectional view for demonstrating the heat transfer method by embodiment of this invention. It is sectional drawing by the one part expansion which shows one reference example of a plasma processing apparatus. It is sectional drawing by the one part expansion which shows another reference example of a plasma processing apparatus.

Explanation of symbols

100: Processing chamber (processing chamber)
DESCRIPTION OF SYMBOLS 101: Lid member 102: Antenna 103: Magnetic field generator 105: High frequency electric power source part 106: Dielectric 107: Quartz plate 108: Shower plate 109: Sample stand 110: Discharge chamber 111: Buffer chamber 112: Process gas line 113: Process Gas cutoff valve 114: Controller 115: Lower ring 116: Inner wall member 117: Outer wall member 118: Base plate 119, 120: Outer chamber 121, 122: Inner chamber 123: Vacuum chamber 124: Inner wall member 128: Support beam 129 : Support base member 131: Exhaust valve 132: Exhaust pump 134: Electrostatic adsorption electrode 135: Dielectric film 136: Electrode cover 137: High voltage power supply 138: Bias power supply 139: Matching circuit 140: Heater 141: Heat exchange medium 142: Heater cover 143: Hinges 201: magnetic field lines 401
501: Motor 402: Clip 403: Integrated inner wall member P: Plasma W: Semiconductor wafer

Claims (4)

Plasma processing in which a sample stage is provided in a processing chamber composed of a vacuum vessel, plasma is formed in the space above the sample stage by applying electromagnetic waves and applying a magnetic field, and a wafer placed on the sample stage is processed by the plasma In the device
A wall surface facing the plasma above the wafer in the processing chamber is provided with a conical inner wall member inclined in a divergent shape toward the bottom along the isomagnetic surface of the magnetic field,
At this time, the plasma processing apparatus is characterized in that the inner wall member is composed of two ring-shaped members which are divided into two vertically. The plasma processing apparatus according to claim 1,
The plasma processing apparatus, wherein the two ring-shaped members are controlled to different temperatures. In the plasma processing apparatus according to claim 1 or 2,
Of the two ring-shaped members, the upper ring-shaped member includes a substantially cylindrical outer peripheral wall member arranged on the outer periphery,
The plasma processing apparatus, wherein the outer peripheral wall member is provided with heating means on the outer peripheral surface thereof. The plasma processing apparatus according to any one of claims 1 to 3,
The plasma processing apparatus, wherein the sample stage is disposed immediately above a gas exhaust path in the processing chamber.

Images