JP2005150606A - Plasma treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a configuration capable of controlling, at an arbitrary temperature, respective portions within a treatment chamber in a plasma treatment apparatus. <P>SOLUTION: In the plasma treatment apparatus including a plasma generating means (high frequency power source 8, matching circuit 9, antenna 10) capable of generating plasma within the treatment chamber, a means (substrate placing electrode 5, high frequency power source 18, matching circuit 19) for applying a high frequency power to a material 17 to be treated, and the treatment chamber to which a vacuum exhaustion device 7 is connected and which is capable of reducing its internal pressure, the treatment chamber is composed of an upper portion 1 of the treatment chamber which comprises a heating part 20 and becomes a high temperature portion, and a lower portion 3 of the treatment chamber which comprises a cooling part 21 and becomes a low temperature portion, and a central portion 2 of the treatment chamber provided between both the portions is defined as a heat insulating part composed of e.g. foaming aluminum having a heat conduction modulus of ≤10 (W/mK). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus suitable for performing an etching process on a target substrate such as a semiconductor substrate using plasma.

  In the semiconductor manufacturing process, dry etching using plasma is generally performed. Various types of plasma processing apparatuses for performing dry etching are used.

  A plasma processing apparatus generally includes a vacuum vessel, a gas supply system connected to the vacuum vessel, an exhaust system for maintaining a pressure in the processing chamber at a predetermined value, an electrode for mounting a substrate, and an antenna for generating plasma in the vacuum vessel And a shower plate for uniformly supplying the processing gas into the vacuum vessel. When the high frequency power is supplied to the antenna, the processing gas supplied from the shower plate into the processing chamber is dissociated to generate plasma, and etching of the substrate placed on the substrate mounting electrode proceeds.

  In such a plasma etching processing apparatus, a part of a reaction product generated by etching of a substrate or a part of a sputtered processing chamber constituent member adheres to a processing chamber wall or the like without being exhausted and becomes particles. In addition, there is a problem that a change in plasma density and composition due to a change in the state of the inner wall and a change in etching performance are caused.

  As a method for removing reaction products and the like attached to the inner wall of the processing chamber, there is dry cleaning using plasma. For example, if the silicon-based reaction product attached to the inner wall of the processing chamber is generated by using a fluorine-based gas (for example, sulfur hexafluoride) to generate plasma, The reaction product reacts with fluorine generated by the plasma to form silicon fluoride, which is removed from the processing chamber wall and exhausted to the outside of the processing chamber. By performing such reaction product removal at an appropriate time interval such as between wafers or lots, the processing chamber wall can be kept in a state where no reaction product is adhered.

  However, in order to remove the reaction product adhering to the inner wall of the processing chamber, “time for removing the reaction product” is required, and there is a problem that the production efficiency is lowered. It is important not to adhere.

  In general, since the amount of the reaction product deposited decreases with increasing temperature, the “time for removing the reaction product” is short, and the production efficiency is also increased. The temperature up to what degree C depends on the reaction product that adheres and the material of the processing chamber.

  However, when the temperature is raised, the reaction products are less likely to adhere, but the processing chamber components themselves are likely to be released by sputtering or chemical reaction, and the material (reaction products) that jumps out adheres to the walls of the processing chamber. It becomes easy. Conversely, by lowering the temperature of the processing chamber wall, the constituent material of the processing chamber wall is less likely to be released by sputtering or chemical reaction.

  Therefore, when considering the temperature distribution in the processing chamber, the location where the reaction product is not desired to be deposited may be set at a high temperature, and the location where the processing chamber wall constituent material is not desired to be released by sputtering or chemical reaction may be set at a low temperature.

In order to solve such a problem, there is a method in which an insulator having low thermal conductivity is provided to block heat (for example, see Patent Document 1). By providing an insulator having low thermal conductivity, heat transfer in the plasma processing apparatus is limited, so that a portion that is desired to have a high temperature can be a high temperature and a portion that is desired to be a low temperature can be a low temperature. However, since this method uses an insulator to block heat, the portion surrounded by the insulator becomes electrically unstable, which may affect the plasma and the process.
Japanese Patent No. 3265047

  The present invention provides a plasma processing in which a plasma processing chamber is thermally cut off so that a high temperature portion and a low temperature portion can be provided, and an electrically indefinite portion is not formed without being electrically cut off. An object is to provide an apparatus.

  In order to solve the above-described problems, the present invention provides a plasma processing apparatus in which a high temperature portion is provided at the upper portion and a low temperature portion is provided at the lower portion in order to thermally shut them off and to electrically connect them. A central portion made of foamed aluminum is provided between the upper and lower portions of the processing chamber. Foamed aluminum is conductive because it is a metal (aluminum), but its thermal conductivity is low because it has many small cavities inside it. The rate is about 1/100. In order to keep the vacuum, the surface on the vacuum side is processed to seal the hole.

Furthermore, the present invention is provided with means for heating the quartz plate or the shower plate in order to provide a high temperature portion in the processing chamber. As a means for heating the quartz plate or the shower plate, a heater that generates heat by passing an electric current, or a heater made of an electromagnetic wave absorber such as silicon carbide (SiC) or zirconium oxide (ZrO ₂ ) that generates heat by absorbing electromagnetic waves is used. The surface of the quartz plate or shower plate is heated to 150 ° C. or higher.

  Furthermore, in the present invention, a cooling means is provided at the lower part of the processing chamber working as a ground to cool to 30 ° C. or lower.

  By using this foamed aluminum in a place where it is desired to thermally shut off, it is possible to provide a high temperature portion and a low temperature portion in the plasma processing apparatus. In addition, since the foamed aluminum is a metal, the plasma processing chamber can be thermally separated, and at the same time, the plasma processing chamber can be electrically set to the same potential.

  According to the present invention described above, the inside of the plasma processing apparatus can be set and controlled to a desired temperature. As a result, the amount of reaction product deposited in the processing chamber can be arbitrarily controlled, so that an effect can be expected for stable operation of the plasma process, reduction of foreign matter, and the like.

  In the above embodiments, the dry etching apparatus using the UHF-ECR method has been described as an example, but other discharges (capacitively coupled discharge, inductively coupled discharge, magnetron discharge, surface wave excited discharge, TCP discharge, etc.) were used. The dry etching apparatus has the same effect. Further, not only the dry etching apparatus but also other plasma processing apparatuses such as a plasma CVD apparatus, an ashing apparatus, and a surface modification apparatus have the same effects.

  The configuration of the plasma processing apparatus according to the first embodiment of the present invention will be described using the plasma etching processing apparatus shown in FIG. 1 as an example. The plasma etching processing apparatus according to the present embodiment includes a processing chamber upper portion 1, a processing chamber central portion 2, a processing chamber lower portion 3, a quartz shower plate 4, a substrate mounting electrode 5, a quartz plate 6, an exhaust system 7, and a high frequency power source. 8, the matching circuit 9, the antenna 10, the dielectric 11, the antenna cover 12, the coils 13, 14, 15, the yoke 16, the high frequency power source 18, the matching circuit 19, the heater 20, the refrigerant pipe 21, and the like. A substrate 17 to be processed is placed on the substrate placement electrode 5.

  The processing chamber upper portion 1, the processing chamber central portion 2, and the processing chamber lower portion 3 are made of aluminum or an aluminum alloy. In particular, the central portion 2 of the processing chamber is made of foamed aluminum having a thermal conductivity of 10 (W / mK) or less, and performs a process of closing holes on the vacuum side surface in order to maintain the vacuum in the processing chamber.

  A processing gas supplied between the shower plate 4 and the quartz plate 6 from a gas supply system not shown in the drawing is supplied into the etching processing apparatus through a number of holes provided in the shower plate 4. The pressure in the etching apparatus is measured by a vacuum gauge not explicitly shown in the figure, and is exhausted by an exhaust system 7 having pressure control means so as to be a predetermined pressure.

  High frequency power for generating plasma is supplied from the high frequency power supply 8 to the antenna 10 via the matching circuit 9. Around the antenna 10, a dielectric 11 and an antenna cover 12 constituting an electromagnetic wave waveguide are provided.

  Further, coils 13, 14, and 15 for generating a magnetic field in the processing chamber are provided on the outer periphery of the processing chamber, and a yoke 16 is provided so that the magnetic field does not leak outside. Further, a high frequency power source 18 is connected via a matching circuit 19 in order to apply a bias voltage to the substrate 17 to be processed on the substrate mounting electrode 5.

  A heater 20 for heating the shower plate 4 via the antenna 10 and the quartz plate 6 is provided above the antenna 10. A refrigerant pipe 21 for cooling the processing chamber lower part 3 is provided on the atmosphere side (outside) of the processing chamber lower part 3, and a refrigerant controlled to a predetermined temperature flows in the refrigerant pipe 21. Yes.

For example, Ar (100 ml / min) and CF ₄ (50 ml / min) are introduced into the processing chamber through the shower plate 4 as a processing gas, and etching is performed while controlling the pressure in the exhaust system 7 so as to be 1.0 (Pa). The inside of the processing apparatus is exhausted. A power source capable of generating a high frequency of 450 (MHz) is used as the high frequency power source 8 connected to the antenna 10, a high frequency power of 400 (W) is supplied to the antenna 10, and the processing chamber is used using the coils 13 to 15. When an isomagnetic surface of 0.016 (T) is formed on the surface, electron cyclotron resonance occurs on the isomagnetic surface, and plasma is efficiently generated in the etching processing apparatus.

  When a silicon wafer is used as the substrate 17 to be processed, the substrate 17 to be processed is etched by the plasma generated on the vacuum side of the upper portion 1 of the processing chamber, the central portion 2 of the processing chamber 2 and the lower portion 3 of the processing chamber. At this time, the high-frequency power source 18 connected to the substrate mounting electrode 5 is 800 kHz and applies high-frequency power of 100 (W) to the substrate 17 to be processed. Here, from the viewpoint of measures against foreign matter, the shower plate 4 above the wafer is desired to be temperature controlled to a high temperature (for example, 100 ° C.) in order to suppress the adhesion of reaction products and reduce the generation of foreign matter. The lower part 3 of the processing chamber below the wafer is desired to be controlled at a low temperature (for example, −20 ° C.) in order to prevent metal release by sputtering or chemical reaction and reduce metal contamination.

  First, let us consider a case where the processing chamber upper portion 1, the processing chamber central portion 2, and the processing chamber lower portion 3 of the etching processing apparatus are all aluminum. The temperature of the shower plate 4 is controlled to 100 ° C. using the heater 20, and at the same time, the temperature of the lower part 3 of the processing chamber is controlled to −20 ° C. using the refrigerant pipe 21. In this case, the temperature distribution in each processing chamber is as shown in FIG. That is, the temperature in each part of the processing chamber does not become the target value, and the heat applied to the shower plate 4 is transferred to aluminum having good heat conduction and escapes to the lower portion 3 of the processing chamber. The fact that the temperature control is impossible means not only that the desired performance cannot be obtained but also wastes energy.

  On the other hand, let us consider a case in which the processing chamber upper portion 1 and the processing chamber lower portion 3 use aluminum, and the processing chamber central portion 2 uses a metal having a thermal conductivity of 10 (W / mK) or less. As in the above example, the temperature of the shower plate 4 is controlled to 100 ° C. using the heater 20, and at the same time, the temperature of the lower part 3 of the processing chamber is controlled to −20 ° C. using the refrigerant pipe 21. The temperature distribution in this case is as shown in FIG. 3. The shower plate 4 and the upper part 1 of the processing chamber are 100 ° C., the central part 2 of the processing chamber is 25 ° C. (room temperature), and the lower part 3 of the processing chamber 3 is −20 ° C. Become temperature. As a result, problems such as foreign matter are solved and energy is not wasted.

  Foamed aluminum can be used as a metal material having a thermal conductivity of 10 (W / mK) or less constituting the central portion 2 of the processing chamber. In this case, in order to maintain the vacuum in the processing chamber, a process of sealing the hole on the vacuum side surface of the foamed aluminum forming the central portion 2 of the processing chamber is performed.

  The configuration of the plasma processing apparatus according to the second embodiment of the present invention will be described with reference to FIG. The configuration of the plasma processing apparatus according to this embodiment is basically the same as that of the first embodiment shown in FIG. 1, except that a heater for heating the shower plate 4 is shown in FIG. 4, the heater 22 is installed on the atmosphere side (outside) of the shower plate 4 in FIG. 4. The effect of heating the shower plate 4 can be similarly achieved in the configuration of this embodiment. Further, in FIG. 4, conductive O-rings 31 are used for vacuum sealing between the processing chamber upper portion 1 and the processing chamber central portion 2 and between the processing chamber central portion 2 and the processing chamber lower portion 3. Since the conductive O-ring 31 is used for the vacuum seal, the processing chamber upper part 1, the processing chamber central part 2, and the processing chamber lower part 3 are maintained at the same potential, and an electrically stable plasma is generated to stabilize the process. As in the first embodiment, the temperature distribution in the processing chamber can be maintained as intended, and the reaction product can be controlled.

  The plasma processing apparatus according to the third embodiment of the present invention is characterized in that in the plasma processing apparatus shown in FIG. 1, means for heating the surface of the quartz plate 6 or the shower plate 4 provided in the processing chamber is provided. In the plasma processing apparatus according to this embodiment, the output of the heater 20 is increased so that the surface temperature of the quartz plate 6 or the shower plate 4 is 150 ° C. or higher.

  In general, when a plasma treatment using a fluorine-based gas is performed in a plasma treatment apparatus made of aluminum or an alloy thereof, a part of the surface of aluminum is sputtered or a chemical reaction is caused to be chemically stable and removed. It turns into difficult aluminum fluoride. However, it can be seen that when the surface temperature of the processing chamber is heated to 150 ° C. or higher, the aluminum fluoride does not adhere as shown in FIG. In FIG. 5, the horizontal axis represents the temperature of the processing chamber, and the vertical axis represents the amount of adhered aluminum. That is, by heating the processing chamber to 150 ° C. or higher, aluminum fluoride does not adhere to the surface of the processing chamber, and processing can always be performed on the surface of the processing chamber without deposits.

  A plasma processing apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is characterized in that an electromagnetic wave absorber is used as a heating means for the shower plate 4. In FIG. 6, an electromagnetic wave absorber 41 is provided above the shower plate 4 as a heating means for the shower plate 4. The electromagnetic wave absorber 41 absorbs electromagnetic waves (energy) from the antenna 10 to heat the electromagnetic wave absorber, and the heat is transmitted to the shower plate 4, thereby heating the shower plate 4. As the electromagnetic wave absorber 41, SiC or ZrO2 can be used.

  The plasma processing apparatus cools the processing chamber upper part 1, the processing chamber central part 2, and the processing chamber lower part 3, particularly the processing chamber lower part 3, which acts as an earth, and thereby metal by sputtering or chemical reaction from the processing chamber lower part 3. The metal contamination is reduced by preventing the release of methane.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic explaining the structure of the plasma processing apparatus concerning this invention. The figure explaining process chamber temperature distribution at the time of heating an upper part and cooling a lower part, without thermally insulating a process chamber upper part and a process chamber lower part. The figure explaining the temperature distribution in a process chamber at the time of thermally insulating the process chamber upper part and process chamber lower part concerning this invention, heating an upper part, and cooling the lower part. Schematic explaining the structure of the plasma processing apparatus concerning this invention which electrically connected the processing chamber upper part and the processing chamber lower part using the electroconductive O-ring. The figure explaining that AlF does not adhere at the temperature of 150 degreeC or more. Schematic explaining the structure of the plasma processing apparatus concerning this invention which uses the electromagnetic wave absorber for shower plate heating.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Upper part of processing chamber, 2 ... Center part of processing chamber, 3 ... Lower part of processing chamber, 4 ... Shower plate, 5 ... Substrate mounting electrode, 6 ... Quartz plate, 7 ... Exhaust system, 8 ... High frequency power supply, 9 ... Matching circuit DESCRIPTION OF SYMBOLS 10 ... Antenna, 11 ... Dielectric, 12 ... Antenna cover, 13-15 ... Coil, 16 ... Yoke, 17 ... Substrate to be processed, 18 ... High frequency power supply, 19 ... Matching circuit, 20, 22 ... Heater, 21 ... Refrigerant Pipe, 31 ... conductive O-ring, 41 ... electromagnetic wave absorber

Claims (10)

Plasma generating means capable of generating plasma in the processing chamber, means for applying high-frequency power to the material to be processed, a processing chamber to which an evacuation apparatus is connected, the inside of which can be depressurized, and gas to the processing chamber In a plasma processing apparatus comprising a supply device,
A plasma processing apparatus, wherein a metal having a thermal conductivity of 10 (W / mK) or less is used as a part of a processing chamber constituent material.   2. The plasma processing apparatus according to claim 1, wherein foamed aluminum is used as a material having a thermal conductivity of 10 (W / mK) or less.   3. The plasma processing apparatus according to claim 1, wherein a conductive O-ring is used as an O-ring for vacuum sealing.   4. The plasma processing apparatus according to claim 1, wherein the quartz plate in the processing chamber or the surface of a shower plate for uniformly supplying a processing gas to the inside of the plasma processing apparatus is heated. A plasma processing apparatus.   5. The plasma processing apparatus according to claim 4, wherein the surface temperature of the quartz component in the processing chamber or the shower plate is heated to 150 ° C. or higher.   6. The plasma processing apparatus according to claim 4, wherein a heater is used as the shower plate heating means.   6. The plasma processing apparatus according to claim 4, wherein an electromagnetic wave absorber is used as the shower plate heating means.   8. The plasma processing apparatus according to claim 7, wherein silicon carbide (SiC) is used as the electromagnetic wave absorber. 8. The plasma processing apparatus according to claim 7, wherein zirconium oxide (ZrO ₂ ) is used as an electromagnetic wave absorber.   10. The plasma processing apparatus according to claim 1, wherein a part acting as a ground in the plasma processing chamber is set to 30 ° C. or less. 11.

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