Back to results
US 2010/0136793 A1Published application
Efficient and accurate method for real-time prediction of the self-bias voltage of a wafer and feedback control of esc voltage in plasma processing chamber
AssigneeApplied Materials, Inc.
InventorsZhigang Chen, Shahid Rauf, Walter R. Merry, Leonid Dorf, Kartik Ramaswamy, Kenneth S. Collins
Life of this patent
Estimating the term…
Abstract
In a plasma reactor having an electrostatic chuck, wafer voltage may be determined from RF measurements at the bias input using previously determined constants based upon transmission line properties of the bias input, and this wafer voltage may be used to accurately control the DC wafer clamping voltage.
Claims20
A plasma reactor, comprising:
- a wafer support;
- a radio frequency (RF) match network coupled to the wafer support;
- a first RF power source coupled to the RF match network and capable of operating at a first frequency;
- a second RF power source coupled to the RF match network and capable of operating at a second frequency different than the first frequency;
- a direct current (DC) power source coupled to the wafer support;
- a measurement instrument coupled to the RF match network for measuring a voltage at the match network attributable to each of the first frequency and the second frequency;
- and
- a controller capable of calculating a wafer voltage signal as a function of the measured voltage and for calculating a DC voltage at a wafer on the wafer support, the controller also capable of adjusting DC power applied to the wafer support from the DC power source in response to the calculated wafer voltage signal.
5 more elements
A method of processing a wafer while controlling an electrostatic chuck clamping voltage, comprising:
- applying a first RF current to the electrostatic chuck through an RF match network at a first frequency from a first RF power source;
- applying a second RF current to the electrostatic chuck through the RF match network at a second frequency from a second RF power source;
- applying DC voltage to the electrostatic chuck;
- measuring a third RF current at the match network attributable to the first frequency;
- measuring a fourth RF current at the match network attributable to the second frequency;
- calculating a wafer voltage at the first and second frequencies based upon the measured third and fourth currents;
- calculating a DC component of the wafer voltage attributed to each frequency;
- calculating a total DC voltage at the wafer based upon the DC component attributable to each frequency and a DC component attributable to an intermodulation of the first and second frequency;
- and
- adjusting the applied DC voltage to maintain a predetermined difference between the applied DC voltage and the total DC voltage at the wafer.
7 more elements
A method of processing a wafer while controlling an electrostatic chuck clamping voltage in a plasma reactor, comprising:
- applying a first RF current to the electrostatic chuck through an RF match network at a first frequency from a first RF power source;
- applying a second RF current to the electrostatic chuck through the RF match network at a second frequency from a second RF power source;
- applying DC voltage to electrostatic chuck;
- applying a third RF current to a gas distribution showerhead of the plasma reactor at a third frequency from a third RF power source;
- measuring a fourth RF current at the match network attributable to the first frequency;
- measuring a fifth RF current at the match network attributable to the second frequency;
- calculating a wafer voltage at the third frequency based upon the third current, the fourth current and the fifth current;
- calculating the DC component of the wafer voltage attributed to the first frequency, the second frequency, and the third frequency;
- calculating the total DC voltage at the wafer based upon the DC component attributable to each frequency;
- adjusting the applied DC voltage to maintain a predetermined difference between the applied DC voltage and the total DC voltage at the wafer.
7 more elements
Dependencies are inferred from the claim text.