Control of etch rate using modeling, feedback and impedance match

Patent metadata

Field	Value
Publication number	US-9620334-B2
Application number	US-201414152729-A
Country	US
Kind code	B2
Filing date	Jan 10, 2014
Priority date	Dec 17, 2012
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A method for achieving an etch rate is described. The method includes receiving a calculated variable associated with processing a work piece in a plasma chamber. The method further includes propagating the calculated variable through a model to generate a value of the calculated variable at an output of the model, identifying a calculated processing rate associated with the value, and identifying based on the calculated processing rate a pre-determined processing rate. The method also includes identifying a pre-determined variable to be achieved at the output based on the pre-determined processing rate and identifying a characteristics associated with a real and imaginary portions of the pre-determined variable. The method includes controlling variable circuit components to achieve the characteristics to further achieve the pre-determined variable.

First claim

The invention claimed is:

1. A method for achieving an etch rate, comprising:
receiving a value of a variable measured at an output of a radio frequency (RF) generator, wherein the measured value is associated with processing a work piece in a plasma chamber, wherein the plasma chamber is coupled to an impedance matching circuit via an RF transmission line, wherein the output of the RF generator is coupled to the impedance matching circuit via an RF cable;
propagating the measured value of the variable through a computer-generated model to generate a calculated value of the variable at an output of the computer-generated model;
identifying a calculated processing rate associated with the calculated value of the variable;
identifying based on the calculated processing rate a pre-determined processing rate to be achieved;
identifying a pre-determined variable to be achieved at the output of the computer-generated model based on the pre-determined processing rate;
identifying a first characteristic associated with a real portion of the pre-determined variable, the first characteristic of a first variable circuit component within the impedance matching circuit;
controlling the first variable circuit component to achieve the first characteristic to further achieve the real portion of the pre-determined variable;
identifying a second characteristic associated with an imaginary portion of the pre-determined variable, the second characteristic of a second variable circuit component within the impedance matching circuit; and
sending a signal to the second variable circuit component to achieve the second characteristic to further achieve the imaginary portion of the pre-determined variable.

2. The method of claim 1 , wherein the calculated value of the variable includes a complex voltage and current.

3. The method of claim 1 , wherein the first variable circuit component includes a capacitor and the first characteristic includes a capacitance of the capacitor.

4. The method of claim 1 , wherein the second variable circuit component includes a capacitor and the second characteristic includes a capacitance of the capacitor.

5. The method of claim 1 , wherein the first variable circuit component includes an inductor and the first characteristic includes an inductance of the inductor.

6. The method of claim 1 , wherein the second variable circuit component includes an inductor and the second characteristic includes an inductance of the inductor.

7. The method of claim 1 , further comprising:
sending a signal to a controller of the RF generator to change a frequency of operation of the RF generator to achieve the pre-determined processing rate.

8. The method of claim 7 , wherein processing the work piece comprises etching the work piece or depositing a material on the work piece.

9. The method of claim 1 , wherein the second variable circuit component is coupled to an inductor of the impedance matching circuit.

10. The method of claim 9 , wherein the inductor is coupled to the plasma chamber.

11. The method of claim 1 , wherein the RF generator is coupled to the first and second variable circuit components.

12. The method of claim 1 , wherein each of the first variable circuit component and the second variable circuit component is coupled to an output of the RF generator.

13. The method of claim 1 , wherein the first variable circuit component is coupled to the second variable circuit component.

14. The method of claim 1 , wherein the method is used to process semiconductor wafers to make integrated circuits.

15. The method of claim 1 , wherein propagating the measured value of the variable through the computer-generated model comprises computing a directional sum of the measured value of the variable and one or more values that are characteristics of circuit elements of the computer-generated model.

16. The method of claim 1 , wherein the calculated processing rate comprises an etch rate or a deposition rate, wherein the calculated processing rate is associated with the calculated value of the variable when an achievement of the calculated value of the variable facilitates an achievement of the calculated processing rate.

17. The method of claim 1 , wherein the pre-determined processing rate comprises an etch rate or a deposition rate, wherein the pre-determined processing rate is associated with the pre-determined variable when an achievement of the pre-determined variable facilitates an achievement of the pre-determined processing rate.

18. The method of claim 1 , wherein the pre-determined variable comprises an impedance.

19. The method of claim 1 , wherein the real portion is a constant independent of a change in a frequency of operation of the RF generator and the imaginary portion is dependent on the frequency of operation of the RF generator.

20. A host controller comprising:
a memory device for storing a complex variable;
a host processor coupled to the memory device, the host processor for:
receiving a value of a variable measured at an output of a radio frequency (RF) generator, wherein the measured value is associated with processing a work piece in a plasma chamber, wherein the plasma chamber is coupled to an impedance matching circuit via an RF transmission line, wherein the output of the RF generator is coupled to the impedance matching circuit via an RF cable;
propagating the measured value of the variable through a computer-generated model to generate a calculated value of the variable at an output of the computer-generated model;
identifying a calculated processing rate associated with the calculated value of the variable;
identifying based on the calculated processing rate a pre-determined processing rate to be achieved;
identifying a pre-determined variable at the output of the computer-generated model based on the pre-determined processing rate;
identifying a first characteristic associated with a real portion of the pre-determined variable, the first characteristic of a first variable circuit component within the impedance matching circuit;
sending a signal to the first variable circuit component to achieve the first characteristic to further achieve the real portion of the pre-determined variable;
identifying a second characteristic associated with an imaginary portion of the pre-determined variable, the second characteristic of a second variable circuit component within the impedance matching circuit; and
sending a signal to the second variable circuit component to achieve the second characteristic to further achieve the imaginary portion of the pre-determined variable.

21. The host controller of claim 20 , wherein the calculated value of the variable includes a complex voltage and current.

22. A non-transitory computer-readable storage medium with an executable program stored thereon, wherein the program instructs a processor to perform the following operations:
receiving a value of a variable measured at an output of a radio frequency (RF) generator, wherein the measured value is associated with processing a work piece in a plasma chamber, wherein the plasma chamber is coupled to an impedance matching circuit via an RF transmission line, wherein the output of the RF generator is coupled to the impedance matching circuit via an RF cable;
propagating the measured value of the variable through a computer-generated model to generate a calculated value of the variable at an output of the computer-generated model;
identifying a calculated processing

Assignees

• Lam Res Corp

Inventors

• Lyndaker Bradford J
• Valcore Jr John C
• Marakhtanov Alexei
• Jafarian-Tehrani Seyed Jafar
• Chen Zhigang

Classifications

• H01J37/3299

  Feedback systems · CPC title

• H01J37/32183 Primary

  Matching circuits · CPC title

• H01J2237/334

  Etching · CPC title

• H01J37/32926 Primary

  Software, data control or modelling · CPC title

• G05B17/02

  electric · CPC title