Plasma processing apparatus having high frequency power source with sag compensation function and plasma processing method

• US 20050081999A1
• Filed: 03/09/2004
• Published: 04/21/2005
• Est. Priority Date: 10/17/2003
• Status: Active Grant

• Current Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Watanabe, Seiichi, Tamura, Hitoshi, Yasui, Naoki, Sumiya, Masahiro
• Granted Patent: US 7,615,132 B2
• Time in Patent Office: Days
• US Class Current: 156/345.280
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means
• CPC Class Codes: H01J 37/3266 Magnetic control means
• CPC Class Codes: H01J 37/32706 Polarising the substrate

Abstract

A plasma processing apparatus suitable for high-speed and high-definition etching is provided. By applying to a wafer chucking electrode 9 a voltage waveform in which an absolute value of high frequency voltage increases with time and switching between a positive voltage and a negative voltage occurs, a rectangular high frequency voltage is caused to be generated in the wafer 10, with the result that the duty ratio of the rectangular high frequency voltage decreases and that the high energy ion ratio in the energy distribution of ions incident on the wafer increases. Therefore, high efficiency and high accuracy etching becomes possible, providing the advantage that the material selection ratio is improved.

Claims

1. A plasma processing apparatus, comprising:

a plasma generation means which generates plasma within the interior of a processing chamber;

a means for applying a high frequency voltage to an object to be processed;

a processing chamber to which a vacuum system is connected and the interior of which can be depressurized; and

a gas supply device which supplies a gas to the interior of the processing chamber;

wherein the plasma processing apparatus has a means for applying a high frequency voltage in which a high frequency voltage waveform generated in the object to be processed is such that a positive constant voltage and a negative constant voltage alternate with each other at given cycles.

2. The plasma processing apparatus according to claim 1, wherein the high frequency voltage waveform generated in the object to be processed is a substantially rectangular wave.

5. The plasma processing apparatus according to claim 1 or 3, wherein the object to be processed is placed on an electrode which is coated with a dielectric film.

6. The plasma processing apparatus according to claim 1 or 3, wherein the means for applying a high frequency voltage, which becomes a voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, is constituted by a DC power source and a switching circuit (a chopper circuit).

7. The plasma processing apparatus according to claim 1 or 3, wherein the means for applying a high frequency voltage, which becomes a voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, is constituted by a DC power source and a switching circuit (a chopper circuit), which uses as switch elements a thyristor, a GTO (agate turn-off thyristor), an IGBT (an insulated gate bipolar transistor), a MOSFET and a power transistor.

8. The plasma processing apparatus according to claim 1 or 3, wherein the means for applying a high frequency voltage, which becomes a voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, is constituted by an arbitrary voltage waveform generator and a high frequency power amplifier.

9. The plasma processing apparatus according to claim 1 or 3, wherein the means for applying a high frequency voltage, which becomes a voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, can vary the duty ratio of a voltage waveform being output.

10. The plasma processing apparatus according to claim 1 or 3, wherein the means for applying a high frequency voltage, which becomes a voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, is constituted by a sine wave output power source.

11. The plasma processing apparatus according to claim 1 or 3, wherein in the means for applying a high frequency voltage, which becomes a voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, the given cycles are in the range of 0.25 μ

sec to 100 μ

sec (frequency;

10 kHz to 4 MHz).

3. A plasma processing apparatus, comprising:

a plasma generation means which generates plasma within the interior of a processing chamber;

a means for applying a high frequency voltage to an object to be processed;

a processing chamber to which a vacuum system is connected and the interior of which can be depressurized; and

a gas supply device which supplies a gas to the interior of the processing chamber;

wherein the plasma processing apparatus has, as a means for applying a high frequency voltage to the object to be processed, a high frequency power source which generates a high voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, and a high frequency voltage waveform control circuit (a sag correction circuit) which increases with time an absolute value of voltage on at least either of the positive side and the negative side of said voltage waveform.

4. The plasma processing apparatus according to claim 3, wherein the high frequency power source which generates a high voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles is a high frequency power source which generates a substantially rectangular wave.

12. The plasma processing apparatus according to claim 3, wherein the high frequency voltage waveform control circuit (the sag correction circuit) is a clip circuit constituted by a semiconductor element, such as a diode and an FET, and a capacitor or the like.

13. The plasma processing apparatus according to claim 3, wherein the high frequency voltage waveform control circuit (the sag correction circuit) has the function of increasing with time an absolute value of voltage on at least either of the positive side and the negative side of said rectangular high frequency voltage waveform with respect to a monitored quantity, and performing control so that the high frequency voltage waveform generated in the object to be processed becomes substantially rectangular.

14. The plasma processing apparatus according to claim 3, wherein the high frequency voltage waveform control circuit (the sag correction circuit) has the function of detecting as a monitored quantity at least any one of a current of an wafer chucking electrode, a voltage generated in the object to be processed, a current which flows into the object to be processed, a power applied to the object to be processed and an output power of the high frequency power source, increasing with time an absolute value of voltage on at least either of the positive side and the negative side of said rectangular high frequency voltage waveform, and performing control so that the high frequency voltage waveform generated in the object to be processed becomes substantially rectangular.

15. The plasma processing apparatus according to claim 3, wherein the high frequency voltage waveform control circuit (the sag correction circuit) has the function of detecting as a monitored quantity at least any one of a current of an wafer chucking electrode, a voltage generated in the object to be processed, a current which flows into the object to be processed, a power applied to the object to be processed and an output power of the high frequency power source, computing an approximate monitored quantity, increasing with time an absolute value of voltage on at least either of the positive side and the negative side of said rectangular high frequency voltage waveform, and performing control so that the high frequency voltage waveform generated in the object to be processed becomes substantially rectangular.

16. A plasma processing method in a plasma processing apparatus which comprises:

a plasma generation means which generates plasma within the interior of a processing chamber;

a means for applying a high frequency voltage to an object to be processed;

a processing chamber to which a vacuum system is connected and the interior of which can be depressurized; and

a gas supply device which supplies a gas to the interior of said processing chamber;

wherein the method comprises applying a high frequency voltage in which a high frequency voltage waveform generated in the object to be processed is such that a positive constant voltage and a negative constant voltage alternate with each other at given cycles.

17. The plasma processing method according to claim 16, wherein the high frequency voltage waveform generated in the object to be processed is a substantially rectangular wave.

18. The plasma processing method according to claim 16, wherein in the high frequency voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, the duty ratio is varied according to process conditions of the object to be processed.