JP2005116818A - Plasma generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma generator which has simple device constitution, is easy to control, and has excellent reproducibility. <P>SOLUTION: The plasma generator 100 is equipped with a couple of electrodes 42 and 43 which are arranged in a chamber 40, and a high-frequency power unit 11 which applies high-frequency electric power between the couple of electrodes 42 and 43. Further, the generator is equipped with a voltage/phase difference detecting device 41 which detects peak amplitude of the voltage applied across the electrodes 42 and 43, and the phase difference between a peak amplitude value of the voltage applied between the electrodes 42 and 43 and a current flowing between the electrodes 42 and 43; a voltage controller 12 which performs feedback control over the output voltage of the high-frequency power unit 11, so that the peak amplitude value of the voltage measured by the voltage/phase difference detecting device 41 reaches a set peak amplitude value; and a phase controller 30 which performs control so that the phase difference measured by the voltage/phase difference detecting device 41 reaches a specified phase difference set value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plasma generator used in a plasma etching apparatus and the like, and more particularly to a plasma generator having a simple apparatus configuration, easy control, and good reproducibility.

  A plasma etching apparatus is widely used for forming a pattern of a conductive film or an insulating film in manufacturing a semiconductor device. FIG. 2 shows an example of a plasma generator used in a conventional plasma etching apparatus. The plasma generating apparatus 101 includes a high frequency power supply unit 110 that outputs high frequency power, a chamber 130 in which an object to be processed is etched, and a matching unit 120 provided between the high frequency power supply unit 110 and the chamber 130.

  The high frequency power supply unit 110 includes an internal impedance Zi, one end of which is grounded, and a high frequency power supply device 111 that outputs high frequency power from the other end, and a power control device 112 that controls the power output from the high frequency power supply device 111. . The power control device 112 receives the power measured by the power detection device 131 via the signal line 134, and the high frequency power supply device 111 is configured so that the power measured by the power detection device 131 becomes a predetermined power setting value. Feedback control of output power.

  The matching device 120 includes a voltage / current detection device 121 and a variable impedance device 122. The variable impedance device 122 includes, for example, a series variable capacitor 122A connected in series to the power supply line, and a parallel variable capacitor 122B connected between the power supply line and the ground line. The voltage / current detection device 121 detects the voltage and current of the power supply line and the phase difference therebetween, and is variable via the signal line 123 so that the internal impedance Zi of the high-frequency power supply device 111 and the load impedance are matched. The impedance of the impedance device 122 is adjusted.

  The chamber 130 includes a power detection device 131, an upper electrode 132, and a lower electrode 133, and generates a plasma 135 between the electrodes 132 and 133. The power detection device 131 is connected to a power supply line on the downstream side of the matching unit 120, detects plasma power, and transmits the information to the power control device 112 via the signal line 134. The power control device 112 can control the output so that the plasma power measured by the power detection device 131 becomes the set power, and perform plasma etching with the controlled power value.

  In the plasma generator 101 having the above configuration, the output power of the high-frequency power supply device 111 is feedback-controlled so that the power measured by the power detector 131 becomes a set value, so that the plasma power supplied to the chamber 130 is kept constant. Can be controlled. However, when the plasma power is controlled to be constant in this way, the voltage between the electrodes may change greatly as the etching process proceeds. For example, in the case of etching a laminated film in which films made of different materials are laminated, such a problem occurs, and charging damage occurs in the material to be etched due to a change in the etching rate.

With respect to the above problem, Patent Document 1 proposes a plasma processing apparatus that switches a feedback signal in a feedback control of a high-frequency power source between a plasma power and an interelectrode voltage. Patent Documents 2 and 3 also describe a plasma generator that controls a voltage (amplitude value between peaks) applied between electrodes of a chamber to be constant.
JP-A-10-242121 (paragraph 0007) JP-A-8-199378 (paragraph 0009) JP 2001-32077 A (paragraph 0007)

  For example, in the plasma processing apparatus described in Patent Document 1, the etching rate is maintained by switching the feedback control between the plasma power and the voltage between the electrodes according to the progress of the etching process by the switching unit. I have control. As a result, charging damage is suppressed, and plasma etching with little difference between chambers, that is, good reproducibility is obtained.

  However, in the plasma generator of the patent document, it is difficult to control switching between plasma power and interelectrode voltage, and it is difficult to determine the timing of control switching.

  In view of the above, an object of the present invention is to provide a plasma generator having a simple apparatus configuration, easy control, and good reproducibility.

In order to achieve the above object, a plasma generator according to the present invention is a plasma generator comprising a pair of electrodes disposed in a chamber and a high-frequency power supply device that applies a high-frequency power source between the pair of electrodes. ,
Voltage / phase difference detection device for detecting a peak-to-peak amplitude value (V _pp ) of a voltage applied between the electrodes and a phase difference between a voltage applied between the electrodes and a current flowing between the electrodes When,
A voltage control device that controls the output voltage of the high-frequency power supply device so that the peak-to-peak amplitude value of the voltage measured by the voltage / phase difference detection device becomes a set peak-to-peak amplitude value;
And a phase adjuster that controls the phase difference measured by the voltage / phase difference detection device to be a predetermined phase difference setting value.

According to the plasma generator of the present invention, high-frequency power in which the plasma power is well controlled can be supplied to the electrodes while keeping the _Vpp between the electrodes constant by the control of the voltage control device and the phase adjuster. . Therefore, good reproducibility can be obtained by keeping the etching rate constant. Further, according to the plasma generator of the present invention, the plasma power and the V _pp between the electrodes are simultaneously controlled by the voltage control device and the phase adjuster, so the control is performed between the plasma power and the V _pp between the electrodes. There is no need to switch, the control is easy, and the device has a simple configuration.

  Conventionally, when controlling the voltage between electrodes, simultaneous control with plasma power has not been performed, so that plasma power depends on impedance in the chamber or the like. Therefore, the plasma power could not be controlled with high accuracy. However, according to the present invention, by controlling the voltage controller and the phase adjuster via the voltage / phase difference detector, the phase difference between the voltage between the electrodes and the current flowing between the electrodes is simultaneously controlled. The voltage between the electrodes can be controlled with high accuracy, and the plasma power can be controlled with high accuracy.

  In a preferred embodiment of the present invention, the phase adjuster includes a variable impedance device connected between the high-frequency power source and the voltage / phase difference detection device, and is measured by the voltage / phase difference detection device. The variable impedance device is controlled so that the phase difference becomes the predetermined phase difference setting value. This makes it possible to control the phase difference satisfactorily and change the reflected wave of the high-frequency power that travels toward the high-frequency power supply device by reflecting the electrical elements and power supply lines of the variable impedance device to the heat. Since it absorbs, the heat_generation | fever of the high frequency power supply device resulting from a reflected wave can be suppressed.

  In a preferred embodiment of the present invention, the apparatus further comprises an impedance matching unit that is connected between the high-frequency power supply device and the variable impedance device, and matches an internal impedance of the high-frequency power supply device and a load impedance of the high-frequency power supply device. . This provides good impedance matching. Furthermore, in a preferred embodiment of the present invention, the predetermined phase difference set value is made variable, and the plasma density is variably controlled based on the set value.

  Hereinafter, with reference to the drawings, the present invention will be described in more detail based on exemplary embodiments according to the present invention. FIG. 1 shows the configuration of a plasma generator according to an embodiment of the present invention. The plasma generating apparatus 100 includes a high-frequency power supply unit 10 that outputs high-frequency power and a chamber 40 that functions as a reactor that performs plasma etching. In addition, a matching unit 20 provided on the upstream side and a phase adjuster 30 provided on the downstream side are connected between the high-frequency power supply unit 10 and the upper electrode 42 in the chamber 40.

The high frequency power supply unit 10 includes an internal impedance Zi, one end of which is grounded, and a high frequency power supply device 11 that outputs high frequency power from the other end, and a voltage control device 12 that controls a voltage output from the high frequency power supply device 11. . A set value of the interelectrode voltage (V _pp value) is input to the voltage control device 12 in advance. Also, the V _pp value measured by the voltage / phase difference detection device 41 is received via the signal line 44, and the high frequency is set so that the V _pp value measured by the voltage / phase difference detection device 41 becomes a set value. The output voltage of the power supply device 11 is feedback controlled.

  The matching unit 20 includes a voltage / current detection device 21 and a variable impedance device 22. The variable impedance device 22 includes, for example, a series variable capacitor 22A connected in series to the power supply line, and a parallel variable capacitor 22B connected between the power supply line and the ground line. The voltage / current detector 21 detects the voltage and current of the power supply line and the phase difference therebetween, and is variable via the signal line 23 so that the internal impedance Zi of the high frequency power supply 11 and the load impedance are matched. The impedance of the impedance device 22 is adjusted.

  The phase adjuster 30 includes a variable impedance device 31 and a phase control device 32 that controls the impedance of the variable impedance 31 via a signal line 33. The variable impedance device 31 includes, for example, a variable capacitor 31A connected between a power supply line and a ground line, and a variable coil 31B connected between a power supply line on the downstream side and the ground line.

  A phase difference setting value is input to the phase control device 32 in advance. Further, the phase difference between the voltage and current applied between the electrodes 42 and 43 measured by the voltage / phase difference detection device 41 is received via the signal line 45, and this phase difference is set as the phase difference. The impedance of the variable impedance device 31 is controlled so as to be a value. At this time, the electric power supplied to the chamber 40 can be controlled by controlling the phase difference between 0 and π / 2.

The chamber 40 includes a voltage / phase difference detection device 41, an upper electrode 42, and a lower electrode 43, and generates a plasma 46 between the electrodes 42 and 43. The voltage / phase difference detection device 41 measures the voltage V _pp between the electrodes 42 and 43 and the phase difference between the voltage and the current, and provides information on the V _pp value between the electrodes 42 and 43 via the signal line 44. While transmitting to the voltage control apparatus 12, the information of a phase difference is transmitted to the phase controller 31 via the signal line 45. FIG. The upper electrode 42 is supplied with high-frequency power controlled to a voltage having a predetermined V _pp value by the voltage controller 12 and controlled to a predetermined power by controlling the phase difference of the phase controller 33. Thereby, RF having a predetermined ionization energy E is supplied between the electrodes 42 and 43 to generate a plasma 44 having a predetermined density, and plasma etching can be performed.

According to the plasma generator 100 of the present embodiment example, the high frequency power in which the plasma power is well controlled by the control of the voltage controller 12 and the phase controller 33 is maintained, and the V _pp between the electrodes 42 and 43 is kept constant. Can be supplied. Therefore, it is possible to provide the plasma generator 100 having good reproducibility by keeping the etching rate constant. Moreover, the process gas ionized with the low ionization energy E can also be selectively ionized by the favorable controllability of electric power and _Vpp value.

Further, since the power control and the V _pp value are simultaneously controlled by the voltage control device 12 and the phase control device 32, it is not necessary to switch the feedback control between the power and the V _pp value, and the control is easy and simple device configuration. It is possible to provide a plasma generator having

  Furthermore, since the phase adjuster 30 is provided, in addition to the electric elements and the power supply line 50 provided in the matching device 20, the electric elements and the power supply line 50 provided in the phase adjuster 30 are reflected by the upper electrode 42. Since the reflected wave of the high-frequency power that travels toward the high-frequency power device 11 is converted into heat and absorbed, heat generation of the high-frequency power device 11 caused by the reflected wave can be suppressed. Thereby, it is possible to maintain a good function of the high frequency power supply device 11. In the configuration of the plasma generator 100, the matching unit 20 may be omitted when the influence of heat generated by the high frequency power supply device 11 is small. Further, the configuration of the phase adjuster 30 is not limited to the configuration of the present embodiment, and a circuit such as a series circuit, a parallel circuit, a T-type circuit, and a π-type circuit, or a circuit combining these circuits is adopted. I can do it.

  Although the present invention has been described based on the preferred embodiment thereof, the plasma generator according to the present invention is not limited to the configuration of the above-described embodiment example. Plasma generators that have been modified and changed as described above are also included in the scope of the present invention.

It is a figure which shows the structure of the plasma generator which concerns on the embodiment. It is a figure which shows the structure of an example of the conventional plasma generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: High frequency power supply part 11: High frequency power supply device 12: Voltage control device 20: Matching device 21: Voltage current detection device 22A: Series variable capacitor 22B: Parallel variable capacitor 30: Phase adjuster 31: Variable impedance device 31A: Variable capacitor 31B : Variable coil 32: Phase control device 33: Signal line 40: Chamber 41: Voltage / phase difference detection device 42: Upper electrode 43: Lower electrode 44, 45: Signal line 46: Plasma 100: Plasma generator

Claims (4)

In a plasma generator comprising a pair of electrodes disposed in a chamber and a high frequency power supply device that applies a high frequency power source between the pair of electrodes,
A voltage / phase difference detection device for detecting an amplitude value between peaks of a voltage applied between the electrodes and a phase difference between a voltage applied between the electrodes and a current flowing between the electrodes;
A voltage control device that controls the output voltage of the high-frequency power supply device so that the peak-to-peak amplitude value of the voltage measured by the voltage / phase difference detection device becomes a set peak-to-peak amplitude value;
A plasma generator comprising: a phase adjuster that controls the phase difference measured by the voltage / phase difference detection device to be a predetermined phase difference setting value.   The phase adjuster includes a variable impedance device connected between the high-frequency power source and the voltage / phase difference detection device, and the phase difference measured by the voltage / phase difference detection device is the predetermined phase difference. The plasma generating apparatus according to claim 1, wherein the variable impedance apparatus is controlled to be a set value.   3. The plasma generation according to claim 2, further comprising an impedance matching unit connected between the high frequency power supply device and the variable impedance device and configured to match an internal impedance of the high frequency power supply device and a load impedance of the high frequency power supply device. apparatus.   The plasma generator according to claim 1, wherein the plasma density is controlled based on the predetermined phase difference setting value.

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