ENDPOINT DETECTION ALGORITHM FOR ATOMIC LAYER ETCHING (ALE)

• US 20180068831A1
• Filed: 03/08/2017
• Published: 03/08/2018
• Est. Priority Date: 09/02/2016
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Chen, Yan, Tian, Xinkang, Ferns, Jason
• Granted Patent: US 10,453,653 B2
• Time in Patent Office: Days
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32009 Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources plasma generation in general H05H1/24
• CPC Class Codes: H01J 37/32917 Plasma diagnostics
• CPC Class Codes: H01J 37/32963 End-point detection
• CPC Class Codes: H01J 37/32972 Spectral analysis
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/30655 comprising alternated and repeated etching and passivation steps, e.g. Bosch process
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32

Abstract

Described herein are architectures, platforms and methods for determining endpoints of an optical emission spectroscopy (OES) data acquired from a plasma processing system. The OES data, for example, includes an absorption—step process, a desorption—step process, or a combination thereof. In this example, the OES data undergoes signal synchronization and transient signal filtering prior to endpoint determination, which may be implemented through an application of a moving average filter.

Claims

1. A method for determining process endpoint data in a plasma processing system, comprising:

receiving optical emission spectroscopy (OES) data from a plasma processing chamber of the plasma processing system that performs a multi-step plasma process of a substrate, wherein the cyclical multi-step plasma process comprises at least two process steps that are cyclically repeated;

determining a first quiescent portion of the received OES data, the first quiescent portion is an average of a filtered process-step of the multi-step plasma process; and

determining a first endpoint of the determined first quiescent portion.

2. The method of claim 1, wherein the multi-step process is an atomic layer etch (ALE) process.

3. The method of claim 1, wherein the at least two process steps comprise an absorption step and a desorption step, wherein the filtered process-step includes a transient signal—

filtered absorption step or a transient signal—

filtered desorption step.

4. The method of claim 1, wherein the receiving of optical emission spectroscopy (OES) data is synchronized with the at least two process steps that are cyclically repeated.

5. The method of claim 1, further comprising:

removing transients associated with switching the at least two process steps prior to determining of the first quiescent portion.

6. The method of claim 1, wherein the first quiescent portion is derived from an upper envelope of the OES data acquired during a selected process step of the at least two process steps of the multi-step plasma process.

7. The method of claim 6, wherein the selected process step is an absorption step of an atomic layer etching (ALE) process.

8. The method of claim 1 further comprising:

determining a second quiescent portion of the received OES data, the second quiescent portion is an average of a desorption step of an atomic layer etching (ALE) process.

9. The method of claim 8 further comprising:

determining an average of the first quiescent portion and the second quiescent portion.

10. The method of claim 9, wherein the determining endpoint is based from the determined second quiescent portion.

11. The method of claim 9, wherein the determining endpoint is based from the average of the first quiescent portion and the second quiescent portion.

12. The method of claim 1, wherein the determining the first quiescent portion comprises an application of a moving average filter to the filtered process-step.

13. The method of claim 1 further comprising:

removing transient signals of the received OES data prior to the determining the endpoint based on a second quiescent signal.

14. The method of claim 13, wherein determining a second endpoint based on the second quiescent data comprises a principal component analysis.

15. The method of claim 1, wherein determining the first endpoint comprises a principal component analysis.

16. The method of claim 1, wherein determining the first endpoint comprises:

providing a previously-calculated and stored mean optical emission spectroscopy (OES) data matrix [S_avg];

providing a previously-calculated and stored principal component weights vector [P];

forming optical emission spectroscopy (OES) data sets from a first quiescent signal at predetermined time intervals during the cyclical multi-step plasma process;

from each optical emission spectroscopy (OES) data set, subtracting the previously provided mean optical emission spectroscopy (OES) data matrix [S_avg], to de-mean each optical emission spectroscopy (OES) data set;

transforming each de-meaned and non-normalized optical emission spectroscopy (OES) data set into transformed optical emission spectroscopy (OES) data, by calculating at least one element of the transformed optical emission spectroscopy (OES) data vector [T] using the provided principal component weights vector [P];

from the calculated at least one element of the transformed optical emission spectroscopy (OES) data vector [T], further calculating a trend variable f(T_i); and

detecting the first endpoint of the cyclical multi-step plasma process from the calculated values of the trend variable f(T_i) during the cyclical multi-step plasma process.

17. Non-transitory computer readable media storing a program causing one or more controllers to execute a process of determining a plasma process endpoint comprising:

receiving optical emission spectroscopy (OES) data from a plasma processing chamber of a plasma processing system that performs a multi-step plasma process of a substrate, wherein the multi-step plasma process comprises at least two process steps that are cyclically repeated;

filtering transient signals of each process-step;

determining a first quiescent portion of the received OES data, the first quiescent portion is an average of the filtered process-step of the multi-step plasma process; and

determining an endpoint of the determined first quiescent portion.

18. A plasma processing system comprising:

a plasma processing chamber for performing a multi-step plasma process of a substrate, wherein the multi-step plasma process comprises at least two process steps that are cyclically repeated;

a sensor coupled to the plasma processing chamber, the sensor detects the at least two process steps that is represented by an optical emission spectroscopy (OES) data;

an OES module coupled to the sensor and the plasma processing chamber, wherein the OES module is configured to perform the steps of;

receiving the OES data from the sensor;

removing transient signals of the received OES data;

determining a first quiescent portion of the OES data; and

detecting endpoint of the first quiescent portion.

19. The system of claim 18, wherein the multi-step process is an atomic layer etch (ALE) process.

20. The system of claim 19, wherein the at least two process steps comprise an absorption step and a desorption step.

21. The system of claim 18, wherein the optical emission spectroscopy (OES) module is configured to perform the step of:

synchronizing acquisition of the OES data by the sensor with the cyclically repeated process steps of the multi-step plasma process.

22. The system of claim 18, wherein the optical emission spectroscopy (OES) module is configured to perform the step of:

determining a second quiescent portion of the OES data, wherein the second quiescent portion is an average of a filtered desorption—

step process of the multi-step plasma process.

23. The system of claim 18, wherein the first quiescent portion is an average of a filtered absorption—

step process of the multi-step plasma process.

24. The system of claim 23, wherein the absorption—

step process is an atomic layer etching (ALE) process.

25. The system of claim 18, wherein determining the endpoint comprises a principal component analysis.