Plasma processing apparatus

• US 5,571,366 A
• Filed: 10/20/1994
• Issued: 11/05/1996
• Est. Priority Date: 10/20/1993
• Status: Expired due to Term

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Imahashi, Isei, Nishikawa, Hiroshi, Koshimizu, Chishio, Ishii, Nobuo, Tahara, Yoshifumi, Hata, Jiro
• Primary Examiner(s): DANG, THI D
• Application Number:
  US08/327,798
• Time in Patent Office: 747 Days
• Field of Search: 156/345, 156/626.1, 156/627.1, 118/723 I, 204/298.03, 204/298.07, 204/298.06, 204/298.32, 204/298.34, 216/59-61, 216/68
• US Class Current: 156/345.26
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 2237/3343 Problems associated with etching
• 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 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32963 End-point detection
• CPC Class Codes: H01J 37/3299 Feedback systems

Abstract

A plasma processing apparatus includes a chamber having a gas inlet port and a gas discharge port, a rest table, arranged in the chamber, for supporting a wafer which has a surface to be processed, a radio frequency antenna for supplying a radio frequency energy into the chamber, and generating an induced plasma in the chamber, and a radio frequency voltage source for applying a radio frequency voltage to the radio frequency antenna. A pressure and/or light variation in the chamber is measured during generation of the plasma, by a measurement system, and the radio frequency voltage source is controlled based on a signal from the measurement system, so that voltage to be applied to the antenna is controlled according to the pressure and/or light in the chamber.

Claims

1. A plasma processing apparatus comprising:

a processing chamber for plasma processing, having an external wall, said chamber containing within said wall an object having a surface to be processed in a plasma;

induction means for providing a radio frequency induction field within said chamber for generating a plasma within said chamber;

voltage applying means for applying a radio frequency voltage to said induction means;

measuring means for measuring a pressure variation and/or a light intensity variation from the plasma in said chamber during generation of the plasma, and outputting a signal corresponding to the variation;

control means for controlling said radio frequency voltage applying means based on the signal from said measuring means, and controlling said voltage for controlling said plasma within said chamber;

wherein said induction means has a radio frequency antenna arranged outside said chamber, and an insulating member positioned between said radio frequency antenna and said processing chamber; and

wherein said antenna has an inner terminal formed at an inner end of said antenna, an outer terminal formed at an outer end of said antenna, and at least one intermediate terminal formed between said terminals, the terminals being respectively connected to said radio frequency voltage applying means such that currents flow between said inner terminal and said intermediate terminal, between said intermediate terminal and said outer terminal, and between said intermediate terminal and said radio frequency voltage applying means, and said control means independently controls the currents.

2. An apparatus according to claim 1, further comprising electrostatic shield means, arranged between said radio frequency antenna and said insulating member, for preventing an electrostatic field from applying from said radio frequency antenna to said processing chamber.

3. An apparatus according to claim 1, wherein said chamber has a wall portion consisting of said insulating member and opposing the object to be processed, and said radio frequency antenna has a spiral antenna placed on said wall portion.

4. An apparatus according to claim 1, wherein said measurement means measures an emission intensity of a first gas component whose amount present in said processing chamber relatively and greatly varies in an etching process with respect to the object to be processed, and an emission intensity of a second gas component whose amount existent in said processing chamber does not relatively vary in the etching process, and outputting a signal corresponding to an emission intensity ratio, and said control means controls said radio frequency voltage applying means in accordance with a variation in emission intensity ratio.

5. An apparatus according to claim 1, wherein said measurement means measures a pressure in said processing chamber, and comprises pressure measurement means for outputting a signal corresponding to the pressure, and said control means controls said radio frequency voltage applying means such that the pressure represented by the signal falls within a pressure range wherein an etching rate obtained from a correlation between the pressure in said processing chamber and an etching rate obtained when the etching process is performed with respect to the object to be processed placed in an etching atmosphere falls within a range.

6. An apparatus according to claim 1, wherein said measuring means comprises at least two spectroscopes each measuring an intensity of different wavelength from the plasma, and outputting a signal based on the two intensities.

7. A plasma processing apparatus comprising:

a processing chamber for plasma processing, having an external wall, said chamber containing within said wall an object having a surface to be processed in a plasma;

induction means for providing a radio frequency induction field within said chamber for generating a plasma within said chamber;

voltage applying means for applying a radio frequency voltage to said induction means;

measuring means for measuring a pressure variation and/or a light intensity variation from the plasma in said chamber during generation of the plasma, and outputting a signal corresponding to the variation;

control means for controlling said radio frequency voltage applying means based on the signal from said measuring means, and controlling said voltage for controlling said plasma within said chamber; and

wherein said measuring means has light detecting means for measuring an emission spectrum of a gas present in said processing chamber, and a shortwave component of light emitted from said processing chamber, and outputting a first signal corresponding to the measured emission spectrum and a second signal corresponding to the shortwave component, and said control means detects a state of the plasma based on the first signal, and corrects a detection result using the second signal to control said radio frequency voltage applying means.

8. An apparatus according to claim 7, wherein said control means for controlling said radio frequency voltage applying means controls said radio frequency voltage applying means such that the voltage to be applied is intermittently applied during a process with respect to the object to be processed, and the plasma is intermittently formed.

9. An apparatus according to claim 8, wherein said measuring means has light detecting means for measuring an emission spectrum of a gas present in said processing chamber, and a shortwave component of light emitted from said processing chamber, and outputting a first signal corresponding to the measured emission spectrum and a second signal corresponding to the shortwave component, and said control means detects a state of the plasma based on the first signal, and corrects a detection result using the second signal to control said radio frequency voltage applying means.

10. An apparatus according to claim 7, wherein said induction means has a radio frequency antenna arranged outside said chamber, and an insulating member positioned between said radio frequency antenna and said processing chamber.

11. An apparatus according to claim 7, wherein said voltage applying means comprises a first voltage applying means for applying a first frequency voltage to said induction means and a second voltage applying means for intermittently applying a second frequency voltage to said induction means.

12. A plasma processing apparatus comprising:

a chamber for plasma processing having an external wall, said chamber containing within said wall an object having a surface to be processed in a plasma;

induction means for providing a radio frequency induction field within said chamber for generating a plasma within said chamber, said induction means being coaxially arranged on an imaginary plane being parallel to the surface to be processed and having at least a first inner coil and a second outer coil which are insulated with each other;

supplying means for respectively supplying radio frequency currents to said first inner coil and second outer coil for controlling said plasma within said chamber;

phase control means for controlling phases of the radio frequency currents supplied to said first inner coil and second outer coil; and

pressure detecting means for detecting a pressure in said processing chamber and outputting a signal corresponding to the detected pressure, and means for controlling a power supplied to said first radio frequency coil and a power supplied to said second radio frequency coil to have a division ratio based on the signal from said pressure detecting means.

13. An apparatus according to claim 12, wherein said first radio frequency coil has a partially notched one-turn flat annular coil having a pair of end portions which are separated from each other by an interval, and electrodes provided to said end portions, and said second radio frequency coil surrounds said first coil by an interval while being electrically insulated from said first coil, and has a partially notched one-turn flat annular coil having a pair of end portions which are separated from each other by an interval, and electrodes provided to said end portions.

14. An apparatus according to claim 13, further comprising a cylindrical electromagnetic shield mesh coaxially arranged between said first coil and said second coil and having two open ends.

15. An apparatus according to claim 12, further comprising an electromagnetic shield cylindrical portion coaxially arranged between said first coil and said second coil and having two open ends, said cylindrical portion having a slit extending from one end to the other end.

16. A plasma processing apparatus comprising:

a processing chamber for plasma processing an object received in the chamber;

a plurality of radio frequency antennas disposed outside of the chamber and arranged side by side and spaced from each other, the antennas providing a radio frequency induction field within the chamber for generating a plasma therein;

a plurality of radio frequency power supplies each of which is connected to the corresponding radio frequency antenna for supplying a radio frequency voltage thereto; and

control means for controlling the radio frequency voltage from the radio frequency voltage power supplies.

17. An apparatus according to claim 16, further including means for maintaining said processing chamber at a gas pressure of 10 to 100 mTorr during the process with respect to the object to be processed.

18. An apparatus according to claim 16, further including means for processing the object to be processed at an electron temperature of 2 to 5 eV.

19. An apparatus according to claim 16, wherein each of said antennas has an inner terminal formed at an inner end of each antenna, an outer terminal formed at an outer end of each antenna, and at least one intermediate terminal formed between the inner terminal and the outer terminal;

the inner terminal, outer terminal and intermediate terminal being respectively connected to the radio frequency power supply such that currents flow between the inner terminal and the intermediate terminal, between the intermediate terminal and the outer terminal, and between said intermediate terminal and the radio frequency power supply, and said control means independently controls the currents.

20. An apparatus according to claim 16, wherein said antennas are arranged in a matrix form.

21. A plasma processing apparatus comprising:

a chamber for plasma processing having an external wall, said chamber containing within said wall an object having a surface to be processed in a plasma;

induction means for providing a radio frequency induction field within said chamber for generating a plasma within said chamber, said induction means being coaxially arranged on an imaginary plane being parallel to the surface to be processed and having at least a first inner coil and a second outer coil which are insulated with each other;

supplying means for respectively supplying radio frequency currents to said first inner coil and second outer coil for controlling said plasma within said chamber;

phase control means for controlling phases of the radio frequency currents supplied to said first inner coil and second outer coil;

wherein said phase control means controls the phase of the radio frequency current supplied to said first radio frequency coil and the phase of the radio frequency current supplied to said second radio frequency coil to be the substantially same phases or phases shifted by about 180°

from each other; and

reflected power detecting means for detecting reflected powers from said respective radio frequency coils, and wherein said phase control means has a phase shifter for adjusting the phases of the respective radio frequency currents supplied to said respective radio frequency coils to have a phase difference so as to minimize the reflected powers detected by said reflected power detecting means.