Liquid etch endpoint detection and process metrology

• US 6,406,641 B1
• Filed: 06/17/1997
• Issued: 06/18/2002
• Est. Priority Date: 06/17/1997
• Status: Expired due to Term

• Current Assignee: LumaSense Technologies Holdings, Inc. (Advanced Energy Industries, Inc. (China))
• Original Assignee: Luxtron Corp. (Advanced Energy Industries, Inc. (China))
• Inventors: Golzarian, Reza
• Primary Examiner(s): ALANKO, ANITA KAREN
• Application Number:
  US08/877,537
• Time in Patent Office: 1,827 Days
• Field of Search: 438/8, 438/756, 438/757, 438/754, 216/85
• US Class Current: 216/85
• CPC Class Codes: G01B 11/0683 measurement during deposition or removal of the layer

Abstract

A semiconductor process endpoint detection system uses a relatively wide wavelength range of light to reflect off a semiconductor wafer being processed. Relatively narrow wavelength ranges can be monitored within this wide reflected wavelength range in order to produce an endpoint of the process. An indication can be produced which is a function of detected light intensities at multiple wavelength ranges. These indications aid in the determination of an endpoint of a process.

Claims

1. A method comprising:

producing light with a light source;

reflecting light from the light source off of a semiconductor wafer;

detecting light reflected off of the semiconductor wafer during a wet etch of a deposited dielectric over a grown dielectric; and

determining the endpoint of the semiconductor process using an intensity indication, where the intensity indication is produced from the combination of two or more discrete signals obtained from two or more different wavelength ranges.

2. The method of claim 1, wherein the wet etch is a wet etch of a deposited silicon oxide over a grown silicon oxide.

3. The method of claim 1, further comprising producing a displayed graph of a wavelength indication versus detected intensity.

4. The method of claim 3, further comprising selecting from the display at least one wavelength range of interest to detect during the wet etch.

5. A method of monitoring a material removal process, comprising:

providing a semiconductor wafer including a top layer of a first structure and an underlayer of another structure;

removing material from the top layer;

producing light with a light source;

reflecting light from the light source off of the wafer;

detecting light reflected off of the semiconductor wafer; and

determining the endpoint of the material removal process using an intensity indication produced from the detected light as a result of the underlayer having a different surface roughness when exposed than the top layer.

6. A method, comprising:

producing light with a light source;

reflecting light from the light source off of a semiconductor wafer;

detecting light reflected off of the semiconductor wafer during a wet etch of an anti-reflective aluminum; and

determining the endpoint of the semiconductor process using an intensity indication produced from the detected light, wherein the intensity indication is produced from the combination of two or more discrete signals obtained from two or more different wavelength ranges.

7. A method, comprising:

placing a liquid etchant on a semiconductor wafer to etch a wafer layer, the liquid etchant reacting with the wafer layer forming substances in the liquid etchant;

producing light with a light source;

reflecting light from the light source through the liquid and off of the wafer, at least some of the reflected light being altered by substances in the liquid etchant;

detecting light reflected off of the semiconductor wafer; and

determining the endpoint of the semiconductor process using an intensity indication produced from the detected light, the intensity indication changing as a result of the amount of the substances formed in the liquid etchant near the endpoint, wherein the intensity indication is produced from the combination of two or more discrete signals obtained from two or more different wavelength ranges.

8. A method, comprising:

providing a semiconductor wafer including a top layer of a first structure and an underlayer of another structure;

producing light with a light source;

reflecting light from the light source off of the wafer;

detecting light reflected off of the semiconductor wafer; and

determining the endpoint of the semiconductor process using an intensity indication produced from the detected light, the intensity indication changing as a result of the exposure of the underlayer, the exposed underlayer having a different surface roughness when exposed than the top layer, wherein the intensity indication is produced from the combination of two or more discrete signals obtained from two or more different wavelength ranges.

9. A method of monitoring removal of a layer of material that is being carried by a substrate, comprising:

directing light onto the layer in a manner to be reflected therefrom,

detecting the reflected light as the layer of material is being removed, and

determining when the magnitude of the detected reflected light changes as a result of exposure of a structure under the layer of material that has a different surface roughness than does the layer being removed.

10. The method of claim 9, wherein the substrate is a semiconductor wafer.

11. The method of claim 9, wherein the determination of when the magnitude of detected reflected light changes provides an indication of an endpoint of material removal.

12. The method of claim 9, wherein the layer of material being removed includes deposited silicon oxide and the structure under this layer includes thermally grown oxide.