Plasma processing apparatus, radio frequency generator and correction method therefor

• US 8,073,646 B2
• Filed: 03/28/2008
• Issued: 12/06/2011
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Sato, Kenji
• Primary Examiner(s): TSAI, CAROL S W
• Application Number:
  US12/058,215
• Publication Number:
  US 20080237031A1
• Time in Patent Office: 1,348 Days
• Field of Search: 702/106, 156/345.32, 156/345.24, 156/345.28, 156/345.47, 156/345.31, 156/345.38, 156/345.25, 156/345.43, 118/712, 118/719, 118/728, 118/723.R, 118/723.E, 216/41, 216/59, 216/60, 216/61, 333/33, 333/32, 333/17.3, 333/133, 333/99.PL, 324/707, 324/464, 324/96, 324/117, 315/111.21
• US Class Current: 702/106
• 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 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32183 Matching circuits
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

A plasma processing apparatus includes a radio frequency generator capable of adjusting a target output power level based on the set power level and the offset level to output radio frequency power; a chamber in which a plasma process is performed; and a power detection unit for measuring radio frequency power level fed to the matching unit. The plasma processing apparatus further includes a generator control unit for controlling the radio frequency power such that the radio frequency power level fed to the matching unit reaches the set power level by calculating the offset level based on the difference between the set power level and the power level measured by the power detection unit and transmitting the set power level and the offset level in digital form to the data input terminal of the radio frequency generator.

Claims

1. A plasma processing apparatus comprising:

a processing chamber that accommodates a substrate to be processed therein and capable of being exhausted to a vacuum level;

a gas supply unit that supplies a process gas into the processing chamber to perform a plasma process;

an exhaust unit that exhausts the process gas used to perform the plasma process;

a radio frequency generator, which includes a data input terminal to which a set power level of radio frequency power and an offset level for calibrating output power are inputted as digital data and a power output terminal that outputs the radio frequency power, capable of adjusting a target output power level based on the set power level and the offset level to output radio frequency power corresponding to the target output power level via the power output terminal;

a matching unit, connected to the radio frequency generator via a transmission line, that matches an impedance of a radio frequency generator side with an impedance of a chamber side;

an electrode, provided in the processing chamber, to which radio frequency power from the matching unit is applied;

a power detection unit, interposed between the transmission line and the matching unit, that measures a radio frequency power level fed to the matching unit; and

a generator control unit that, when calibrating the radio frequency generator, controls the radio frequency power from the power output terminal of the radio frequency generator such that the radio frequency power level fed to the matching unit reaches the set power level by calculating the offset level based on the difference between the set power level and the power level measured by the power detection unit and transmitting the set power level and the offset level in digital form to the data input terminal of the radio frequency generator.

2. The plasma processing apparatus of claim 1, wherein the transmission line is formed of a coaxial cable.

3. The plasma processing apparatus of claim 1, wherein the digital data is serial data.

4. The plasma processing apparatus of claim 1, wherein the radio frequency generator calculates the target output power level by multiplying the set power level with the offset level.

5. The plasma processing apparatus of claim 1, wherein the radio frequency generator includes a radio frequency power stabilizing circuit that stabilizes the radio frequency power from the power output terminal to be maintained at the target output power level.

6. A plasma processing apparatus comprising:

a processing chamber that accommodates a substrate to be processed therein and capable of being exhausted to a vacuum level;

a gas supply unit that supplies a process gas into the processing chamber to perform a plasma process;

an exhaust unit that exhausts the process gas used to perform the plasma process;

a radio frequency generator, which includes a power output terminal that outputs radio frequency power, capable of adjusting a target output power level based on a set power level of radio frequency power and an offset level for calibrating output power to output radio frequency power corresponding to the target output power level via the power output terminal;

a matching unit, connected to the radio frequency power via a transmission line, that matches an impedance of a radio frequency generator side with an impedance of a chamber side;

an electrode, provided in the processing chamber, to which radio frequency power from the matching unit is applied; and

a power detection unit, interposed between the transmission line and the matching unit, that measures a radio frequency power level fed to the matching unit,

wherein the radio frequency generator retains an automatic calibration function of adjusting the radio frequency power from the power output terminal of the radio frequency generator such that the radio frequency power level fed to the matching unit reaches the set power level by receiving a power level measured by the power detection unit, calculating the offset level based on the difference between the measured power level and the set power level, and adjusting the target output power level based on the offset level and the set power level.

7. A method for calibrating a radio frequency generator to which a load is connected via a transmission line by using a generator control unit, the radio frequency generator including a data input terminal to which a set power level of radio frequency power and an offset level for calibrating output power are inputted as digital data and a power output terminal that outputs the radio frequency power, a target output power level is adjusted based on the set power level and the offset level, and radio frequency power corresponding to the target output power level is outputted via the power output terminal, the method comprising:

adjusting the target output power level by inputting a set power level for calibration and an offset level for calibration to the data input terminal of the radio frequency generator by the generator control unit and outputting radio frequency power corresponding to the target output power level via the power output terminal;

renewing the offset level for calibration based on the difference between radio frequency power level applied to the load, which has been measured by a power detection unit interposed between the transmission line and the load, and the set power level by the generator control unit to transmit the renewed offset level for calibration to the data input terminal of the radio frequency generator;

repeating the step of adjusting the target output power level and the step of renewing the offset level for calibration to transmit it until the measured power level reaches the set power level; and

setting the offset level for calibration when the measured power level reaches the set power level as an offset level for calibrating the output power of the radio frequency generator.

9. The method of claim 7, wherein the offset level for calibration changes according to a half of the difference between the measured power level and the set power level.

11. The method of claim 7, wherein the load includes a chamber in which a plasma process is performed on a substrate to be processed by plasma generated by radio frequency power supplied from the radio frequency generator via the transmission line and a matching unit, installed between the transmission line and the chamber, that matches the impedance between the chamber and the transmission line.

8. A method for calibrating a radio frequency generator to which a load is connected via a transmission line, the radio frequency generator including a power output terminal that outputs radio frequency power, and is configured such that a target output power level is adjusted based on a set power level of radio frequency power and an offset level for calibrating output power and radio frequency power corresponding to the target output power level is outputted via the power output terminal, the method comprising:

adjusting the target output power level based on a set power level for calibration and an offset level for calibration by the generator control unit to output radio frequency power corresponding to the target output power level via the power output terminal of the radio frequency generator;

renewing the offset level for calibration based on the difference between radio frequency power level applied to the load, which has been measured by a power detection unit interposed between the transmission line and the load, and the set power level by the radio frequency generator;

repeating the step of adjusting the target output power level and the step of renewing the offset level for calibration until the measured power level reaches the set power level; and

setting the offset level for calibration when the measured power level reaches the set power level as an offset level for calibrating the output power of the radio frequency generator.

10. The method of claim 8, wherein the offset level for calibration changes according to a half of the difference between the measured power level and the set power level.

12. The method of claim 8, wherein the load includes a chamber in which a plasma process is performed on a substrate to be processed by plasma generated by radio frequency power supplied from the radio frequency generator via the transmission line and a matching unit, installed between the transmission line and the chamber, that matches the impedance between the chamber and the transmission line.

13. A radio frequency generator comprising:

an oscillator;

a level adjustment unit that adjusts an output level of the oscillator;

an amplifying unit that amplifies an output from the level adjustment unit;

a power output terminal that transmits radio frequency power from the amplifying unit;

a data input terminal to which a set power level of the radio frequency power and an offset level for calibrating the output power from the power output terminal are inputted as digital data; and

a power control unit that calculates a target output power level based on the set power level and offset level inputted to the data input terminal, and controls the level adjustment unit such that radio frequency power corresponding to the target output power level is outputted via the power output terminal.

14. A radio frequency generator comprising:

an oscillator;

a level adjustment unit that adjusts an output level of the oscillator;

an amplifying unit that amplifies an output from the level adjustment unit;

a power output terminal that transmits radio frequency power from the amplifying unit to a transmission line; and

a power control unit that receives power measured by a power detection unit connected to an end portion of the transmission line, calculates an offset level by using the difference between the measured power level and a set power level of radio frequency power, computes a target output power level based on the offset level and the set power level, and controls the level adjustment unit such that radio frequency power corresponding to the target output power level is outputted via the power output terminal.