Plasma processing apparatus

Abstract

A plasma processing apparatus including a chamber having an inner wall with a protective film thereon and a sample stage disposed in the chamber in which plasma is generated by supplying high-frequency wave energy to processing gas to conduct plasma processing for a sample on the sample stage using the plasma. The apparatus includes a control device which determines, based on monitor values of a wafer attracting current monitor (Ip) to monitor a current supplied from a wafer attracting power source, an impedance monitor (Zp) to monitor plasma impedance viewed from a plasma generating power source, and an impedance monitor (Zb) to monitor a plasma impedance viewed from a bias power supply, presence or absence of occurrence of an associated one of abnormal discharge in inner parts, deterioration in insulation of an insulating film of a wafer attracting electrode, and abnormal injection in a gas injection plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram to explain a first embodiment of a plasma processing apparatus.

FIG. 2 is a diagram showing states of monitor values in a normal operation.

FIG. 3 is a diagram to explain in detail the change with respect to time of a direct current (dc) outputted from a wafer attracting power source 16.

FIG. 4 is a diagram showing a change in the plasma potential Pp.

FIG. 5 is a diagram showing a change in the monitor values when an abnormality occurs in the vicinity of a sample stage 5 or a susceptor 20 covering a periphery of the sample stage 5.

FIG. 6 is a diagram showing monitor values when the mass-production is continuously conducted up to the 305000th wafer while periodically replacing inner cylindrical inner parts 17.

FIG. 7 is a diagram showing changes in the monitor values from when the mass-production is started to when the number of processed wafers exceeds 400000.

FIG. 8 is a diagram to explain history data of the monitor value Ip from when the mass-production is started to when the number of processed wafers exceeds 400000.

FIG. 9 is a magnified view showing a waveform of FIG. 4.

FIG. 10 is a diagram showing changes in the plasma potential Pp and the wafer attracting power source voltage Vp in an operation in which control is conducted to reduce the voltage value Vp applied from the wafer attracting power source Vp to the sample stage when the plasma potential Pp increases.

FIG. 11 is a diagram to explain a plasma processing apparatus in which the plasma generating high-frequency power is introduced from a sample stage arranged in a lower section of the chamber.

FIG. 12 is a diagram to explain a plasma processing apparatus in which the plasma generating high-frequency power is introduced from a dielectric vacuum window arranged in an upper section of the chamber and a gas inlet is disposed at a position apart from an area with high electric field intensity caused by a plasma generating high-frequency wave.

Claims

1. A plasma processing apparatus, comprising: a chamber in which inner parts with a protective coating thereon is disposed on an inner wall of the chamber;a sample stage disposed in the chamber, the sample stage including a wafer attracting electrode on a sample placing surface thereof, the electrode being insulated from the sample stage by an insulating layer;gas introducing unit including a gas injection plate which disperses and introduces processing gas into the chamber;a plasma generating high-frequency wave power source which supplies high-frequency wave energy to the processing gas introduced into the chamber to thereby generate plasma;a bias applying high-frequency wave power supply which applies a high-frequency bias voltage to the sample stage;a wafer attracting power source which applies a direct-current voltage to the wafer attracting electrode to attract an wafer, thereby conducting plasma processing for the sample placed on the sample stage using the plasma thus generated;a wafer attracting current monitor for monitoring a current supplied from the wafer attracting power source;an impedance monitor provided on a plasma generating side, for monitoring an impedance of the plasma viewed from the plasma generating high-frequency power source;an impedance monitor provided on a bias applying side, for monitoring an impedance of the plasma viewed from the bias applying high-frequency power supply; anda control device for determining, based on monitor values measured by the monitors, presence or absence of abnormal discharge in the inner parts, deterioration in insulation of the sample stage insulating the wafer attracting electrode, and abnormal discharge in the gas injection plate.

2. A plasma processing apparatus according to claim 1, wherein the control device determines presence of insulation breakdown in the protective coating on the inner parts if the monitor value of the wafer attracting current monitor abruptly increases pulse-wise and no variation appears in the monitor value of the impedance monitor on plasma generating side and the impedance value of the impedance monitor on bias applying side.

3. A plasma processing apparatus according to claim 1, further comprising a plasma potential monitor for monitoring a potential of plasma, wherein the control device determines presence of insulation breakdown in the protective coating on the inner parts if the monitor value of the plasma a potential monitor abruptly increases in a pulsating way and no variation appears in the monitor value of the impedance monitor on plasma generating side and the impedance value of the impedance monitor on bias applying side.

4. A plasma processing apparatus according to claim 1, wherein the control device determines presence of abnormal discharge on the sample stage if the monitor value of the impedance monitor on bias applying side and the monitor value of wafer attracting current monitor vary in the form of a rectangular wave and no variation appears in the monitor value of the impedance monitor on plasma generating side.

5. A plasma processing apparatus according to claim 1, further comprising a peak-to-peak voltage monitor for monitoring a peak-to-peak voltage of the bias applying high-frequency wave power supply, wherein the control device determines presence of abnormal discharge on the sample stage if the monitor value of the impedance monitor on bias applying side, the monitor value of the wafer attracting current monitor, and the monitor value of the peak-to-peak voltage monitor vary in the form of a rectangular wave and no variation appears in the monitor value of the impedance monitor on plasma generating side.

6. A plasma processing apparatus according to claim 1, further comprising a peak-to-peak voltage monitor for monitoring a peak-to-peak voltage of the bias applying high-frequency wave power supply, wherein the control device determines presence of abnormal discharge on the gas injection plate if the monitor value of the impedance monitor on plasma generating side, the monitor value of the impedance monitor on bias applying side, the monitor value of the peak-to-peak voltage monitor, and the monitor value of the wafer attracting current monitor vary in the form of a rectangular wave.

7. A plasma processing apparatus according to claim 1, wherein the control device determines presence of deterioration in insulation of the insulating layer to insulate the wafer attracting electrode, in accordance with a history of the monitor value of the wafer attracting current monitor obtained each time the inner parts are replaced.

8. A plasma processing apparatus according to claim 1, further comprising a plasma potential monitor for monitoring a potential of plasma, wherein the control device reduces, if the monitor value of the plasma potential exceeds a predetermined threshold value, an output voltage from the wafer attracting power source to thereby prevent abnormal discharge occurring in the inner parts.

9. A plasma processing apparatus according to claim 1, wherein the control device reduces a potential of the plasma in response to detection of a pulse-like current by the wafer attracting current monitor.

10. A plasma processing apparatus, comprising: a chamber in which inner parts with protective coating thereon is disposed on an inner wall of the chamber;a sample stage disposed in the chamber, the sample stage including a wafer attracting electrode on a sample placing surface thereof, the electrode being insulated from the sample stage by an insulating layer;a gas introducing means including a gas injection plate which disperses and introduces processing gas in the chamber;a bias applying high-frequency wave power supply for applying a high-frequency bias voltage to the sample stage,a plasma generating high-frequency wave power source for applying a high-frequency wave voltage to the sample stage to supply high-frequency wave energy to the processing gas introduced into the chamber to thereby generate plasma;a wafer attracting power source for applying a direct-current voltage to the wafer attracting electrode to attract an wafer, whereby a plasma processing is conducted for the sample placed on the sample stage using the plasma thus generated;a wafer attracting current monitor for monitoring a current supplied from the wafer attracting power source;an impedance monitor provided on a plasma generating side for monitoring an impedance of the plasma viewed from the plasma generating high-frequency power source;an impedance monitor provided on a bias applying side for monitoring an impedance of the plasma viewed from the bias applying high-frequency power supply; anda control device for determining, based on monitor values measured by the monitors, presence or absence of abnormal discharge in the inner parts and deterioration in insulation of the sample stage insulating the wafer attracting electrode.

11. A plasma processing apparatus according to claim 10, wherein the control device determines presence of insulation breakdown in the protective coating on the inner parts if the monitor value of the wafer attracting current monitor abruptly increases pulse-wise and no variation appears in the monitor value of the impedance monitor on plasma generating side and the impedance value of the impedance monitor on bias applying side.

12. A plasma processing apparatus according to claim 10, further comprising a plasma potential monitor for monitoring a potential of plasma, wherein the control device determines presence of abnormal discharge on the sample stage if the monitor value of the impedance monitor on plasma generating side, the impedance value of the impedance monitor on bias applying side, the impedance value of the wafer attracting current monitor, and the impedance value of the plasma potential monitor vary pulse-wise.

13. A plasma processing apparatus according to claim 10, further comprising a peak-to-peak voltage monitor for monitoring a peak-to-peak voltage of the bias applying high-frequency wave power supply, wherein the control device determines presence of abnormal discharge on the sample stage if the monitor value of the impedance monitor on plasma generating side, the impedance value of the impedance monitor on bias applying side, the impedance value of the wafer attracting current monitor, and the impedance value of the peak-to-peak voltage monitor vary in the form of a rectangular wave.

14. A plasma processing apparatus according to claim 10, wherein the control device determines presence of deterioration in insulation of the insulating layer to insulate the wafer attracting electrode, in accordance with a history of the monitor value of the wafer attracting current monitor obtained each time the inner parts are replaced.

15. A plasma processing apparatus according to claim 10, further comprising a plasma potential monitor for monitoring a potential of plasma, wherein the control device prevents, when the monitor value of the plasma potential exceeds a predetermine threshold value, abnormal discharge occurring in the inner parts by reducing a voltage outputted from the wafer attracting power source.

16. A plasma processing apparatus, comprising: a chamber in which inner parts with a protective coating thereon is disposed on an inner wall of the chamber;a sample stage disposed in the chamber, the sample stage including a wafer attracting electrode on a sample placing surface thereof, the electrode being insulated from the sample stage by an insulating layer;a gas introducing unit including a dielectric vacuum window including a gas outlet for introducing processing gas into a central section of the chamber;a bias applying high-frequency wave power supply for applying a high-frequency bias voltage to the sample stage,a plasma generating high-frequency wave power source including a loop-shaped antenna on the vacuum window in an upper section of the chamber applying a high-frequency electromagnetic field via the antenna to the chamber to supply high-frequency wave energy to the processing gas introduced into the chamber to thereby generate plasma;a wafer attracting power source for applying a direct-current voltage to the wafer attracting electrode to attract an wafer, whereby a plasma processing is conducted for the sample placed on the sample stage using the plasma thus generated;a wafer attracting current monitor for monitoring a current supplied from the wafer attracting power source;an impedance monitor provided on a plasma generating side for monitoring an impedance of the plasma viewed from the plasma generating high-frequency power source;an impedance monitor provided on a bias applying side for monitoring an impedance of the plasma viewed from the bias applying high-frequency power supply; anda control device for determining, based on monitor values measured by the monitors, presence or absence of abnormal discharge in the inner parts, deterioration in insulation of the sample stage insulating the wafer attracting electrode, and wearing of the dielectric vacuum window.

17. A plasma processing apparatus according to claim 16, wherein the control device determines presence of insulation breakdown in the protective coating on the inner parts if the monitor value of the wafer attracting current monitor abruptly increases pulse-wise and no variation appears in the monitor value of the impedance monitor on plasma generating side and the monitor value of the impedance monitor on bias applying side.

18. A plasma processing apparatus according to claim 16, wherein the control device determines presence of deterioration in insulation of the insulating layer to insulate the wafer attracting electrode, in accordance with a history of the monitor value of the wafer attracting current monitor obtained each time the inner parts are replaced.

19. A plasma processing apparatus according to claim 16, further comprising a plasma potential monitor for monitoring a potential of plasma, wherein the control device reduces, if the monitor value of the plasma potential exceeds a predetermined threshold value, an output voltage from the wafer attracting power source to thereby prevent abnormal discharge occurring in the inner parts.

20. A plasma processing apparatus according to claim 16, wherein the control device determines reduction in thickness of the dielectric vacuum window according to a variation in the monitor value of the impedance monitor on plasma generating side.