In-situ reflectometry for real-time selectivity monitoring

1 . A method of monitoring film selectivity on a substrate, comprising:

generating light from a light source;

collimating the light from the light source to form a collimated light beam;

directing, into a process chamber, the collimated light beam to a substrate surface during an epitaxial process;

reflecting the collimated light beam off of the substrate surface to produce a reflected beam;

receiving, by a spectrometer, the reflected beam; and

analyzing data derived from the spectrometer to determine a film selectivity of the epitaxial process;

creating a calibration metric, comprising:

generating an initial data set;

performing the epitaxial process on the substrate while positioned on a susceptor assembly;

comparing the initial data set to a second data set derived from the spectrometer; and

generating a third data set by comparing the initial data set to the second data set, the third data set accounting for susceptor assembly wobble.

2 . The method of claim 1 , further comprising modifying an epitaxial process parameter of the process chamber based on the film selectivity.

3 . The method of claim 1 , wherein the reflected beam is about 90° relative to the substrate surface.

4 . The method of claim 1 , wherein the collimated light beam follows a path located in a center of the process chamber and is directed at a center of the substrate.

5 . The method of claim 1 , further comprising:

comparing the data derived from a center of the substrate to data derived from a position radially outward from the center of the substrate surface; and

determining the film selectivity based on the data derived from the spectrometer.

6 . The method of claim 1 , wherein the light from the light source is provided through a centrally-located passage in an upper housing module of the processing chamber, and the reflected beam is directed back through the centrally-located passage.

7 . A method of monitoring film selectivity on a substrate, comprising:

generating light from a light source;

collimating the light from the light source to form a collimated light beam;

directing, into a process chamber, the collimated light beam to a substrate surface during an epitaxial process;

reflecting the collimated light beam off of the substrate surface to produce a reflected beam;

receiving, by a spectrometer, the reflected beam; and

analyzing data derived from the spectrometer to determine a film selectivity of the epitaxial process, comprising:

determining, from the data, a rate of change metric indicative of a rate of change of an intensity of the reflected beam; and

determining that the film selectivity is becoming non-selective in response to the rate of change metric meeting a threshold value.

8 . The method of claim 7 , further comprising:

altering processing conditions in response to determining the film selectivity of the epitaxial process.

9 . The method of claim 8 , wherein altering processing conditions comprises:

altering processing conditions in response to determining that the film selectivity of the epitaxial process is becoming non-selective to shift the epitaxial process back to a selective epitaxial process.

10 . A processing chamber, comprising:

a susceptor assembly disposed in a processing volume of the processing chamber and configured to support a substrate;

an in-situ reflectometry (ISR) system configured to determine a film selectivity of an epitaxial process on a substrate, the ISR system comprising:

a light source configured to direct a light to a substrate surface during an epitaxial process; and

a sensor configured to receive a reflected light and generate spectrum data based on the reflected light; and

a controller configured to analyze the spectrum data to determine a film selectivity of the epitaxial process and modify a parameter of the epitaxial process upon determining the epitaxial process is a non-selective epitaxial process.

11 . The processing chamber of claim 10 , wherein the light has a wavelength of about 200 nm to about 800 nm.

12 . The processing chamber of claim 11 , further comprising a collimator configured to collimate the light emitted from the light source.

13 . The processing chamber of claim 10 , wherein the controller receives spectrum data from the sensor to determine the film selectivity.

14 . The processing chamber of claim 13 , wherein:

the sensor is configured to receive the reflected light throughout a duration of the epitaxial process; and

the sensor generates spectrum data based on the reflected light received by the sensor.

15 . A method of film selectivity monitoring, comprising:

determining a selectivity of a film formed on a substrate, comprising:

performing an epitaxial process;

directing light from a light source towards a surface of the substrate along a propagation path;

collecting a reflected light from the surface of the substrate, wherein a spectrometer receives the reflected light;

generating spectrum data based on the reflected light; and

creating a data set as a reference for in-situ reflectometry from the spectrum data.

16 . The method of claim 15 , wherein the data set is associated with the reflected light based on variables comprising at least one of frequency, amplitude, phase shift, and fit to a function.

17 . The method of claim 15 , wherein the data set is generated based on the reflected light based on a physical trigger.

18 . The method of claim 15 , wherein the data set is associated with the reflected light based on instructions executed by a controller.