End point determination of process residues in wafer-less auto clean process using optical emission spectroscopy

• US 6,815,362 B1
• Filed: 05/03/2002
• Issued: 11/09/2004
• Est. Priority Date: 05/04/2001
• Status: Expired due to Fees

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Wong, Vincent, Richardson, Brett C., Lui, Andrew, Baldwin, Scott
• Primary Examiner(s): Vinh, Lan
• Application Number:
  US10/138,980
• Time in Patent Office: 921 Days
• Field of Search: 438/706, 438/710, 438/712, 438/7, 438/8, 438/9, 498/9, 156/345, 134/1.1, 134/1.2
• US Class Current: 438/706
• CPC Class Codes: B08B 7/0035 by radiant energy, e.g. UV, laser, light beam or the like
• CPC Class Codes: C23C 16/4405 Cleaning of reactor or parts inside the reactor by using reactive gases
• CPC Class Codes: H01J 37/32862 In situ cleaning of vessels and/or internal parts
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

A method for determining an endpoint of an in-situ cleaning process of a semiconductor processing chamber is provided. The method initiates with providing an optical emission spectrometer (OES) configured to monitor selected wavelength signals. Then, baseline OES threshold signal intensities are determined for each of the selected wavelength signals. Next, an endpoint time of each step of the in-situ cleaning process is determined. Determining an endpoint time includes executing a process recipe to process a semiconductor substrate within the processing chamber. Executing the in-situ cleaning process and recording the endpoint time for each step of the in-situ cleaning process are also included in determining the endpoint time. Then, nominal operating times are established for each step of the in-situ cleaning process. A plasma processing system for executing a two step in-situ cleaning process is also provided.

Claims

1. A method for determining an endpoint of an in-situ cleaning process of a semiconductor processing chamber, the method comprising:

providing an optical emission spectrometer (OES) configured to monitor selected wavelength signals;

determining baseline OES threshold signal intensities for each of the selected wavelength signals;

determining an endpoint time of each step of the in-situ cleaning process, the determining an endpoint time including;

executing a process recipe to process a semiconductor substrate within the processing chamber;

executing the in-situ cleaning process for the semiconductor processing chamber by first removing a silicon based by-product from an inner surface of the chamber through a fluorine based plasma and upon completion of the removal of the silicon based by-product, removing a carbon based by-product from the inner surface of the chamber through an oxygen based plasma ; and

recording the endpoint time for both the silicon based by-product removal step and the carbon based by-product removal step of the in-situ cleaning process; and

establishing nominal operating times for each removal step of the in-situ cleaning process.

3. The method of claim 1, wherein the method operation of executing the in-situ cleaning process further includes:

flowing a fluorine based gaseous composition into the processing chamber to generate the fluorine based plasma; and

flowing an oxygen based a second gaseous composition into the processing chamber to generate the oxygen based plasma.

4. The method of claim 1, further including:

repeating the determining of the endpoint time of each step of the in-situ cleaning process for at least five times to result in at least five recorded endpoint times for each step of the in-situ cleaning process; and

averaging each of the at least five recorded endpoint times of each step to arrive at an averaged endpoint time for each step of the in-situ cleaning process.

5. The method of claim 1, wherein the selected wavelength signals include at least one wavelength signal from the group consisting essentially of 390 nanometers (nm), 309 nm, 680 nm, 703 nm, and 520 nm.

6. The method of claim 5, wherein the 390 nm wavelength signal indicates an amount of SiF₂ chamber deposition removal products, the 309 nm wavelength signal indicates an amount of SiF_x chamber deposition removal products, and the 520 nm wavelength signal indicates an amount of carbon monoxide (CO) chamber deposition removal products.

7. The method of claim 1, wherein the method operation of determining an endpoint time of each step of the in-situ cleaning process further includes:

calculating a slope of a trace of a signal intensity of each of the selected wavelength signals.

8. The method of claim 7, further including:

defining the endpoint time of each step when the slope of the trace of the signal intensity is about zero after reaching the baseline OES threshold intensity signal for each of the selected wavelength signals.

2. The method of claim l, wherein the process recipe is an etch process.

9. A method for cleaning byproducts deposited on interior surfaces of a semiconductor processing chamber, comprising:

flowing an etchant process gas with a fluorine-containing compound being optimized to remove silicon and silicon compounds;

forming a first plasma from the etchant process gas with the fluorine containing compound to perform a silicon based cleaning step;

detecting an emission intensity of an optical radiation from a reactant product in the first plasma; and

ending the silicon based cleaning step after the emission intensity reaches a threshold value and when a slope of a trace of the emission intensity is about zero;

flowing an etchant process gas with an oxygen-containing compound, the oxygen-containing compound being optimized to remove carbon and carbon compounds;

forming a second plasma from the etchant process gas with the oxygen containing compound to perform a carbon based cleaning step;

detecting an emission intensity of an optical radiation from a product in the second plasma; and

ending the carbon based cleaning step when a slope of a trace of the emission intensity is about zero after the emission intensity reaches a threshold value.

10. The method of claim 9, wherein the reactant is fluorine.

11. The method of claim 9, wherein the optical radiation has a wavelength selected from one of about 309 nanometers (nm), and about 390 nm.

12. The method of claim 9, wherein the method operation of detecting an emission intensity of an optical radiation from one of a reactant in the first plasma further includes:

providing an optical emission spectrometer (OES); and

configuring OES parameters for optimal resolution of the emission intensity of the optical radiation from one of the reactant.

13. The method of claim 12, wherein the OES parameters are selected from the group consisting of charged couple device gain, width, filter type and number of samples.

14. The method of claim 9, wherein the product is carbon monoxide.

15. The method of claim 9, wherein the method operation of detecting an emission intensity of an optical radiation from a product in the first plasma further includes:

providing an optical emission spectrometer (OES); and

configuring OES parameters for optimal resolution of the emission intensity of the optical radiation from the product.