JP2006253204A - Test piece installation electrode of plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a test piece accurately to a predetermined temperature by accurately measuring the pressure of heat transfer gas between the test piece and a flame spraying film. <P>SOLUTION: A plasma processing apparatus includes a substrate 1 in which a cooling medium passage for pouring a cooling medium is formed inside, a heat transfer gas supply groove formed on the flame spraying film 2 formed in the above substrate front surface, and a heat transfer gas passageway 5 which is formed in the above substrate and communicates with the heat transfer gas supply groove. The test piece installation electrode of the plasma processing apparatus performs the electrostatic adsorption of the test piece laid in the heat transfer gas supply groove formation surface of the above flame spraying film, and holds it. The substrate 1 has a pressure nanometer 10 which is connected with the heat transfer gas passageway 5 formed in the above substrate 1, and measures the pressure of the heat transfer gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sample mounting electrode of a plasma processing apparatus, and more particularly to a sample mounting electrode of a plasma processing apparatus capable of accurately measuring the pressure of a heat transfer gas supplied to a sample mounting surface.

  In the semiconductor manufacturing process, dry etching using plasma is generally performed. Various types of apparatuses are used as plasma processing apparatuses for performing dry etching. Such 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, a placement electrode for placing a substrate, and a vacuum vessel And an antenna for generating plasma, a shower plate for uniformly supplying the processing gas into the vacuum vessel, and the like.

  By supplying high-frequency power to the antenna, the processing gas supplied from the shower plate into the processing chamber is dissociated to generate plasma, whereby the etching of the wafer placed on the mounting electrode proceeds.

  In order to ensure the desired etching performance, it is necessary to control a number of parameters such as plasma distribution, composition and density, and one of them is wafer temperature control. In order to control the wafer temperature, a method of controlling the temperature of the refrigerant flowing in the refrigerant groove provided in the wafer mounting electrode, the heat transfer flowing between the wafer electrostatically adsorbed on the sprayed film on the mounting electrode and the sprayed film There is a method for controlling the gas pressure.

  The method of controlling the temperature of the refrigerant flowing in the refrigerant groove provided in the wafer mounting electrode is effective for temperature control over a relatively long time. However, it is not suitable for controlling the refrigerant temperature and further the wafer temperature within a short time. Moreover, the method of controlling the pressure of the heat transfer gas flowing between the wafer and the sprayed film can change the wafer temperature by increasing or decreasing the pressure in a short time. For this reason, it becomes possible to quickly control the wafer temperature to a desired temperature in accordance with the process.

  In order to control the wafer temperature to a desired temperature according to the process, it is necessary to accurately measure the pressure of the heat transfer gas between the wafer and the sprayed film and feed back the value. For example, the heat transfer gas (cooling gas) is measured with a pressure gauge, the mass flow controller is controlled so that the heat transfer gas becomes a predetermined pressure, and the pressure of the heat transfer gas between the wafer and the sprayed film is set to a desired pressure. (See Patent Document 1).

As the pressure gauge used here, a diaphragm vacuum gauge (diaphragm vacuum gauge) is generally used. The diaphragm vacuum gauge is a vacuum gauge that uses a thin metal film and obtains pressure from a change in capacitance when the metal film is slightly deformed by pressure. This vacuum system has the advantage of excellent measurement accuracy. However, it has the disadvantage of being easily affected by external vibration. For this reason, it cannot be used with a wafer mounting electrode in which a coolant is flowing and constantly vibrating. Therefore, in the technique disclosed in Patent Document 1, the pressure of the heat transfer gas must be measured outside the vacuum processing apparatus.
Japanese Patent Laid-Open No. 9-312282

  However, the place where pressure measurement is actually required is the pressure between a sample such as a wafer and the sprayed film. For this reason, as shown in Patent Document 1, an error occurs when the pressure is measured at a position distant from the mounting electrode. Due to this error, the pressure between the sample and the sprayed film cannot be controlled to a predetermined pressure, and as a result, the sample temperature cannot be controlled to a predetermined temperature.

  The present invention has been made in view of these problems, and it is possible to accurately measure the pressure of the heat transfer gas between the sample and the sprayed film and thereby control the sample to a predetermined temperature. An electrode is provided.

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

  A base material in which a refrigerant passage for flowing a refrigerant is formed, a heat transfer gas supply groove formed on a sprayed film formed on the surface of the base material, and a heat transfer gas supply groove formed in the base material and communicating with the heat transfer gas supply groove In the sample mounting electrode of the plasma processing apparatus that includes a heat transfer gas passage that electrostatically adsorbs and holds the sample mounted on the heat transfer gas supply groove forming surface of the sprayed film, the heat transfer gas passage is formed in the base material. A pressure gauge connected to the heat transfer gas passage to measure the pressure of the heat transfer gas was provided in the base material.

  Since the present invention has the above-described configuration, it provides a sample mounting electrode capable of accurately measuring the pressure of a heat transfer gas between a sample and a sprayed film and thereby controlling the sample to a predetermined temperature. Can do.

  Hereinafter, the best embodiment will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a sample mounting electrode according to an embodiment of the present invention. The sample mounting electrode includes a base material 1 serving as an electrode structure, an alumina sprayed film 2, a coolant passage 3 through which a temperature adjusting refrigerant flows, a sample 4 electrostatically adsorbable on the sprayed film, and inside the base material 1 A heat transfer gas passage 5 for supplying heat transfer gas, for example, to a groove-shaped heat transfer space (heat transfer gas supply groove) formed between the sample 4 and the sprayed film 2, and heat transfer gas jets 21 and 22. , 23, a gas supply pipe 13 for supplying a conductive gas to the conductive gas passage 5, a helium gas cylinder 6 for supplying a heat transfer gas (helium), a mass flow controller 7 for controlling the flow rate of the heat transfer gas, and exhausting the gas supply pipe 13 And a circulator 9 for supplying a refrigerant whose temperature is adjusted to a predetermined temperature through the refrigerant passage 3 and pressure gauges 10 and 11 for measuring the pressure of the heat transfer gas. The pressure gauges 10 and 11, the mass flow controller 7, the pump 8, and the valve 12 are connected to a controller (not shown) and can control the pressure in the gas passage so that the pressure gauges 10 and 11 indicate a predetermined pressure. is there. Although not shown, the sample mounting electrode shown in FIG. 1 is installed in the plasma etching apparatus.

  At the time of processing, the sample transported into the plasma etching processing chamber by a transport device (not shown) is placed on the sprayed film 2. After adjusting the processing chamber pressure to a predetermined pressure, plasma is generated in the processing chamber. Next, a bias voltage is applied to the sample via a sample bias supply rod (not shown), and the sample is electrostatically adsorbed to the sprayed film 2.

  The gas flow rate is controlled by controlling the mass flow controller 7 so that the pressure gauge 11 indicating the pressure between the sample 4 and the sprayed film 2 becomes 1.5 kPa. In this pressure control, the exhaust pump 8 is activated as necessary, and the exhaust flow rate is controlled by the valve 12. Since the gas cylinder 6 is filled with helium gas as a heat transfer gas (cooling gas), the space between the sample 4 and the sprayed film 2 is filled with helium gas ejected through the gas ejection ports 21, 22, and 23.

  Further, the refrigerant controlled to 20 ° C. by the circulator 9 is supplied to the refrigerant passage 3 at a flow rate of 10 L / min. Note that the pressure gauge is not used in this flow path.

  This state is a state in which the pressure between the sample 4 and the thermal spray film 2 is measured by the pressure gauge 11 installed outside the base material 1 constituting the sample mounting electrode. The pressure gauge 11 is a diaphragm pressure gauge.

  At this time, the pressure gauge 11 shows 1.5 kPa, but this pressure is only the pressure measured by the pressure gauge 11, and is not the pressure of the heat transfer gas between the sample 4 and the sprayed film 2 for which the pressure is actually to be measured. . That is, the pressure gauge 11, the sample 4 and the sprayed film 2 are connected via the gas supply pipe 13 and the conduction gas passage 5, and these gas passages have conductance. For this reason, the pressure indicated by the pressure gauge 11 does not match the pressure of the heat transfer gas between the sample 4 and the sprayed film 2. Therefore, it is difficult to accurately measure the pressure between the sample 4 and the sprayed film 2 with the pressure gauge 11. However, by arranging the pressure gauge 10 inside the substrate 1 and using this pressure gauge, the pressure of the heat transfer gas between the sample 4 and the sprayed film 2 can be accurately measured.

  FIG. 2 is a diagram for explaining the details of the vicinity of the pressure gauge arranged inside the substrate. As shown in the figure, the pressure gauge 10 is installed in a pressure measurement chamber 20 formed in the equipment 1. The pressure measurement chamber communicates with the gas supply pipe 5, and the inner wall of the pressure measurement chamber 20 is covered with an insulator such as alumina. The pressure gauge 10 and a cable 22 such as a coaxial cable that connects the pressure gauge 10 and a controller (not shown) are covered with a metal-grounded cover 21. The outside of the grounded metal cover 21 is covered with an insulator such as alumina.

  The pressure gauge 10 is close to a heat transfer space formed between the sample 4 and the sprayed film 2. For this reason, the pressure of the heat transfer gas between the sample 4 and the sprayed film 2 can be accurately measured by the pressure gauge 10. Further, by controlling the mass flow controller 7, the valve 12 and the like based on this measured value, the heat transfer space between the sample 4 and the sprayed film 2 can be accurately controlled to a predetermined pressure. For this reason, the sample 4 can be controlled to a desired temperature, which can greatly contribute to the improvement of the etching performance.

  As the pressure gauge 10, a pressure gauge that obtains pressure from a change in the viscosity of the heat transfer gas, such as a quartz friction vacuum gauge or a spinning rotor gauge, can be used. For example, when a diaphragm vacuum gauge is used as the pressure gauge 10, there is a case where an accurate pressure cannot be measured due to a vibration of circulation circulated by the circulator 9. In addition, the pressure gauge itself is large and is difficult to attach to the substrate 1. If, for example, a Pirani vacuum gauge that utilizes a change in thermal conductivity is used as the pressure gauge 10, the filament constituting the vacuum gauge may be deteriorated by the corrosive gas used for etching. On the other hand, when the pressure gauge for obtaining the pressure from the change in the viscosity of the heat transfer gas as in this embodiment is employed, the pressure is accurately and easily measured over a long period because there is no such problem. Can do.

  FIG. 3 is a diagram for explaining an example of wafer temperature control performed based on the measurement value of the pressure gauge 10 disposed in the base material 1.

  As an example of this figure, a quartz friction vacuum gauge is used as the pressure gauge 10 to obtain the pressure from the change in the resonance state of the tuning fork type quartz vibrator due to the change in the viscosity of the heat transfer gas. The pressure measurable range of the quartz friction vacuum gauge is 1 to 100 kPa, and the pressure can be measured over a wide pressure range.

FIG. 3 is a diagram showing the discharge time of the plasma processing apparatus, the pressure of the heat transfer gas between the sample 4 and the sprayed film 2 arranged in the processing chamber constituting the plasma processing apparatus, and the surface temperature of the sample 4. Although not clearly shown in FIG. 1, plasma exists in the processing chamber. The processing conditions at this time are, for example, UHF output of 1000 W, sample bias of 1500 W, and processing gas of CF ₄ of 100 sccm. Further, the pressure in the processing chamber is 3 Pa, and the refrigerant set temperature is 20 ° C.

  As shown in FIG. 3, the pressure of the heat transfer gas (helium) between the sample 4 and the sprayed film 2 is controlled to 1.0 kPa until the discharge time is 0 to 10 seconds. As a pressure control method, the mass flow controller 7, the exhaust pump 8, and the valve 12 are controlled by a controller (not shown) so that the measured value of the pressure gauge 10 is a predetermined value, in this example, 1.0 kPa. At this time, the temperature of the sample 4 is 40 ° C.

  When the discharge time is 10 seconds, it is desired to increase the temperature of the sample 4 in order to increase the etching rate. Therefore, the pressure of the heat transfer gas between the sample 4 and the sprayed film 2 is lowered to 0.5 kPa. Then, the temperature of the sample 4 rises to 50 ° C. This state is maintained until the discharge time reaches 20 seconds. When the discharge time is 20 seconds, it is desired to lower the temperature of the sample 4 in order to lower the etching rate. Therefore, the pressure between the sample 4 and the sprayed film 2 is increased to 1.5 kPa. Then, the temperature of the sample 4 falls to 30 ° C. This state is maintained until the discharge time reaches 25 seconds.

  Since the sample can be brought to a desired temperature by changing the pressure between the sample 4 and the sprayed film 2 in this way, a desired process can be constructed. As described above, when the quartz friction vacuum gauge that obtains the pressure from the change in the gas viscosity is used as the pressure gauge 10, the pressure is accurately measured without being affected by the high frequency during plasma discharge or sample bias application. can do.

  FIG. 4 is a diagram for explaining a sample mounting electrode according to another embodiment of the present invention. The structure of the sample mounting electrode shown in FIG. 4 is basically the same as that of the sample mounting electrode shown in FIG. 1, but the heat transfer gas is supplied to the heat transfer space (heat transfer gas supply groove) and the heat transfer space. A plurality of heat transfer gas passages to be supplied are provided, and the pressure of the heat transfer gas in each heat transfer space can be individually measured and controlled.

  That is, in FIG. 4, the sample surface is such that the gas of pressure A is ejected on the outer peripheral side of the gas outlet 33 of the substrate 1 and the gas of pressure B is ejected on the inner peripheral side of the gas outlet 32. It has a structure that can supply heat transfer gas of two kinds of pressure inside.

  For example, when it is desired to control the pressure on the outer peripheral side from the gas outlet 33 to 2.0 kPa, the sample 4 and the sprayed film are transferred from the gas cylinder 6a via the mass flow controller 7a while the sample 4 is electrostatically adsorbed to the sprayed film 2. Heat transfer gas (helium) is supplied to the outer peripheral side region in the vicinity of the gas outlets 33 and 34 between the two. Further, if necessary, the vacuum pump 8a and the valve 12a are controlled to control the pressure on the outer peripheral side from the gas ejection ports 33 and 34. Similarly, when the pressure on the inner peripheral side from the gas outlet 32 is controlled, it is transmitted from the gas cylinder 6b to the inner peripheral side region in the vicinity of the gas outlets 1, 32 between the sample 4 and the sprayed film 2 via the mass flow controller 7b. Supply hot gas (helium). Further, the pressure on the inner peripheral side from the gas ejection ports 31 and 32 is controlled by controlling the vacuum pump 8b and the valve 12b as necessary.

  FIG. 5 is a diagram for explaining an example of wafer temperature control performed on the basis of the measurement values of the pressure gauges 10a and 10b arranged on the inner peripheral side and the outer peripheral side in the base material 1, respectively. Indicates the control value on the outer peripheral side, and FIG. 5B shows the control value on the inner peripheral side.

  As shown in FIG. 5, until the discharge time is 5 seconds, the pressure of the heat transfer gas (helium) is 1.0 kPa over the entire heat transfer space between the sample 4 and the sprayed film 2, and the sample at this time The temperature of 4 is 40 ° C. When the discharge time reaches 5 seconds, the pressure on the outer peripheral side from the gas outlet 33 is reduced to 0.5 kPa. Then, the temperature of the sample 4 on the outer peripheral side from the gas ejection port 33 rises to 50 ° C. Since there is no pressure change, the sample temperature is constant on the inner peripheral side from the gas jet port 32.

  If the pressure on the inner peripheral side from the gas jet port 32 is reduced to 0.5 kPa in this case with a discharge time of 10 seconds, the temperature of the sample 4 on the inner peripheral side from the gas jet port 32 rises to 50 ° C. accordingly. . In the discharge time of 20 seconds, when the pressure on the inner peripheral side from the gas outlet 32 is 1.5 kPa and the pressure on the outer peripheral side from the gas outlet 33 is 2.0 kPa, the temperature of the sample 4 is 30 in each region. And 27 ° C.

  In this example, the region between the sample and the sprayed film is controlled by dividing it into two regions, but it can be controlled by dividing it into more regions. By dividing the region between the sample and the sprayed film and controlling each region, the sample temperature distribution can be controlled to a desired temperature distribution. In addition, the temperature distribution of the sample can be accurately controlled by providing a pressure gauge, especially a quartz friction vacuum gauge, in the substrate of the sample mounting electrode, and accurately measuring and controlling the pressure between the sample and the sprayed film. it can. Further, although helium gas is used as the heat transfer gas between the sample and the sprayed film, other gases such as argon gas can be used.

  Although the dry etching apparatus has been described above as an example, the same applies to the dry etching apparatus using various discharges (UHF-ECR method, capacitively coupled discharge, inductively coupled discharge, magnetron discharge, surface wave excitation discharge, TCP discharge, etc.). An effect can be obtained. Further, similar effects can be obtained in other plasma processing apparatuses such as a plasma CVD apparatus, an ashing apparatus, and a surface modification apparatus.

It is a figure explaining the sample mounting electrode which concerns on embodiment of this invention. It is a figure explaining the detail of the pressure gauge vicinity arrange | positioned inside a base material. It is a figure explaining the example of the temperature control of the wafer performed based on the measured value of the pressure gauge arrange | positioned in the base material. It is a figure explaining the sample mounting electrode which concerns on other embodiment. It is a figure explaining the example of the temperature control of the wafer performed based on the measured value of the pressure gauge each arrange | positioned in the inner peripheral side and outer peripheral side in a base material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Sprayed film 3 Refrigerant passage 4 Sample 5 5a 5b Conductive gas passage 6 6a 6b Gas cylinder 7 7a 7b Mass flow controller 8 8a 8b Vacuum pump 9 Circulator 10 10a 10b Pressure gauge 11 Pressure gauge 12 12a 12b Valve
13, 13a 13b Gas supply pipe 20 Pressure measurement chamber 21 Cover 22 Cable
21, 22, 23 Gas outlet 31 32 33 34 Gas outlet

Claims (5)

A base material formed with a refrigerant passage through which a refrigerant flows;
A heat transfer gas supply groove formed on the sprayed film formed on the substrate surface;
A heat transfer gas passage formed in the substrate and communicating with the heat transfer gas supply groove;
In the sample mounting electrode of the plasma processing apparatus for electrostatically adsorbing and holding the sample mounted on the heat transfer gas supply groove forming surface of the sprayed film,
A sample mounting electrode of a plasma processing apparatus, comprising a pressure gauge in the base material, which is connected to a heat transfer gas passage formed in the base material and measures the pressure of the heat transfer gas. In the sample mounting electrode of the plasma processing apparatus according to claim 1,
The sample mounting electrode of a plasma processing apparatus, wherein the pressure gauge is a pressure gauge that measures a pressure based on a change in viscosity due to a pressure of a heat transfer gas. In the sample mounting electrode of the plasma processing apparatus according to claim 1,
The sample mounting electrode of a plasma processing apparatus, wherein the pressure gauge is a quartz friction vacuum gauge that measures pressure based on a change in resonance impedance of a quartz crystal resonator. In the sample mounting electrode of the plasma processing apparatus according to claim 1,
The heat treatment gas supply groove and the heat transfer gas passage for supplying the heat transfer gas to the heat transfer gas supply groove are provided with a plurality of systems, respectively, and each system is supplied with a heat transfer gas having a different pressure. Sample mounting electrode of the device. In the sample mounting electrode of the plasma processing apparatus of any one of Claim 1 thru | or 4,
A sample mounting electrode of a plasma processing apparatus, wherein the temperature of a sample is controlled by adjusting a pressure of a heat transfer gas supplied to a heat transfer gas supply groove based on a gas pressure measured by a pressure gauge.

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