Plasma processing device and method of monitoring discharge state in plasma processing device

• US 8,855,949 B2
• Filed: 06/29/2009
• Issued: 10/07/2014
• Est. Priority Date: 07/02/2008
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Nonomura, Masaru
• Primary Examiner(s): Breene, John
• Assistant Examiner(s): HWANG, TIMOTHY
• Application Number:
  US13/001,810
• Publication Number:
  US 20110109530A1
• Time in Patent Office: 1,926 Days
• Field of Search: 702/57
• US Class Current: 702/57
• CPC Class Codes: H01J 2237/0206 Extinguishing, preventing or controlling unwanted discharges
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

An object is to provide a plasma processing device capable of properly monitoring a state of plasma discharge and detecting a precursor to abnormal discharge, and a method of monitoring the state of discharge in the plasma processing device. In analysis processing for monitoring executed by detecting, by a signal analyzing portion 30, a signal of a potential change induced in a discharge detection sensor 23 in response to a change in plasma discharge of the inside of a processing chamber and recorded in a signal recorder 20, based on a counter value N3 obtained by detecting a signal of abnormal discharge (first arc discharge) generated between an electrode portion and an object to be processed by a first detector 33 and a counter value N4 obtained by detecting a signal of micro-arc discharge (second arc discharge) generated by deposition of a foreign substance in the processing chamber by a second detector 35, an abnormal discharge determining portion 39 calculates a difference (N3−N4) and compares the difference (N3−N4) with a threshold value a2 for determination and determines whether there is a possibility of generation of abnormal discharge in the processing chamber.

Claims

1. A plasma processing device comprising:

a vacuum chamber that forms a processing chamber;

an electrode portion arranged in the processing chamber and electrically isolated from the vacuum chamber;

an vacuum exhaust portion configured to exhaust a gas from the processing chamber by vacuum;

a gas supply portion configured to supply a gas which is used for plasma generation into the processing chamber;

a high frequency power supply portion configured to generate plasma discharge in the processing chamber when a high frequency voltage is impressed onto the electrode portion;

a matching device configured to match an impedance of a plasma discharge circuit configured to generate the plasma discharge with an impedance of the high frequency power supply portion;

a discharge detection sensor comprising, at least, a plate-shaped dielectric member arranged such that one surface thereof opposes plasma discharge generated in the processing chamber, and a probe electrode arranged on the other surface of the dielectric member; and

a signal analyzing portion configured to determine a signal of a potential change induced in the probe electrode in response to a change in the plasma discharge and execute analysis processing for monitoring a state of discharge,

wherein said plasma processing device is configured to execute plasma processing for an object to be processed which is placed on the electrode portion to plasma processing,

wherein the signal analyzing portion comprises;

a first detector configured to determine a signal of a potential change induced by first arc discharge generated between the electrode portion and the object to be processed;

a second detector configured to determine a signal of a potential change induced by second arc discharge other than the first arc discharge; and

an abnormal discharge determining portion configured to obtain a difference between a number of determinations by the first detector and a number of determinations by the second detector within predetermined time, to compare the difference with a threshold value, and to determine that there is a possibility of generation of abnormal discharge in the processing chamber if the difference exceeds the threshold value,

wherein a first threshold value for determining the signal of the potential change induced by the first arc discharge is set in the first detector,

wherein a second threshold value for determining the signal of the potential change induced by the second arc discharge is set in the second detector,

wherein an absolute value of the second threshold value is larger than an absolute value of the first threshold value, and

wherein a positive or negative sign of the first threshold value is opposite to that of the second threshold value.

2. A method of monitoring a state of discharge in a plasma processing device, the plasma processing device comprising:

a vacuum chamber that forms a processing chamber;

an electrode portion arranged in the processing chamber and electrically isolated from the vacuum chamber;

an vacuum exhaust portion configured to exhaust a gas from the processing chamber vacuum;

a gas supply portion configured to supply a gas which is used for plasma generation into the processing chamber;

a high frequency power supply portion configured to generate plasma discharge in the processing chamber when a high frequency voltage is impressed onto the electrode portion;

a matching device configured to match an impedance of a plasma discharge circuit configured to generate the plasma discharge with an impedance of the high frequency power supply portion; and

a discharge detection sensor comprising, at least, a plate-shaped dielectric member attached to the vacuum chamber such that one surface thereof opposes plasma discharge generated in the processing chamber, and a probe electrode arranged on the other surface of the dielectric member, wherein said plasma processing device monitors the state of the plasma discharge in the processing chamber, said method comprising;

a signal recording step of receiving a signal of a potential change induced in the probe electrode in response to a change in the plasma discharge, and temporarily storing the signal as signal data indicating the potential change, and

a signal analysis step of executing analysis processing for monitoring a state of the plasma discharge with reference to the temporarily stored signal data,

wherein the signal analysis step comprises;

determining, by a first detector, a signal of a potential change induced by first arc discharge generated between the electrode portion and an object to be processed;

determining, by a second detector, a signal of a potential change induced by second arc discharge other than the first arc discharge;

obtaining a difference between a number of determinations by the first detector and a number of determinations by the second detector within predetermined time;

comparing the difference and a threshold value; and

determining that there is a possibility of generation of abnormal discharge if the difference exceeds the threshold value,

wherein a first threshold value for determining the signal of the potential change induced by the first arc discharge is set in the first detector,

wherein a second threshold value for determining the signal of the potential change induced by the second arc discharge is set in the second detector such that an absolute value of the second threshold value is larger than an absolute value of the first threshold value, and

wherein a positive or negative sign of the first threshold value is opposite to that of the second threshold value.