NON-CONTACT SUBSTRATE TEMPERATURE MEASUREMENT TECHNIQUE BASED ON SPECTRAL INTEFEROMETRY

1 . An apparatus for processing substrates, comprising:

a process chamber;

a substrate support within the process chamber to support a substrate for processing;

a light source directly coupled to a light isolator and configured to deliver incident light to and through a first surface of the substrate when disposed on the substrate support;

an optical fiber having a first end spaced apart a first distance from the first surface and a second end directly coupled to the light source via a coupling element;

a photodetector directly coupled to the second end of the optical fiber via the coupling element and configured to receive a first reflected light beam reflected off the first surface and a second reflected light beam reflected off an inner boundary of a second surface of the substrate, opposite the first surface; and

a signal processor to determine a temperature of the substrate based on the first and second reflected light beams.

2 . The apparatus of claim 1 , wherein the first distance is about 155 mm.

3 . The apparatus of claim 1 , wherein the substrate support further comprises:

a gas hole disposed through a central axis of the substrate support;

one or more holes formed in the substrate support, about the gas hole; and

a corresponding number of lift pins disposed in the one or more holes;

wherein the gas hole and lift pins are configured to hold an optical probe coupled to the first end and disposed between the first end and the first surface.

4 . The apparatus of claim 3 , further comprising a plurality of optical probes disposed in the lift pins and gas hole, wherein the optical fiber couples light source to the optical probes via a multiplexing unit.

5 . The apparatus of claim 1 , further comprising one or more electrodes disposed in the substrate support.

6 . The apparatus of claim 1 , further comprising a heating apparatus disposed in the substrate support.

7 . The apparatus of claim 1 , wherein the substrate support further comprises a cooling apparatus disposed in the substrate support.

8 . The apparatus of claim 1 , further comprising a thermocouple disposed in or proximate the substrate support.

9 . The apparatus of claim 1 , further comprising a multiple-substrate holder, the multiple-substrate holder comprising:

a bottom member;

one or more vertical supports extending from the bottom member; and

a plurality of vertically spaced apart substrate support planes attached to the vertical supports, wherein each substrate support plane holds a substrate when multiple substrates are disposed in the process chamber.

10 . The apparatus of claim 9 , wherein the light source is configured to deliver light to and through a first surface of each substrate when disposed mounted on the multiple-substrate holder;

wherein a photodetector is configured to receive first reflected light beams reflected off the first surface of each substrate and second reflected light beams reflected off an inner boundary of a second surface of each substrate, opposite the first surface of each substrate; and

wherein a signal processor is configured to determine a temperature of each substrate based on the first and second reflected light beams corresponding to each substrate.

11 . A method for measuring a temperature of a substrate comprising:

(a) irradiating a substrate inside a processing chamber with light;

(b) receiving a first reflection of the light from a first surface of the substrate;

(c) receiving a second reflection of the light through the substrate from an inner boundary of a second surface opposite the first surface; and

(d) determining a substrate temperature based on a spectral analysis of an interference pattern of the first and second reflections.

12 . The temperature measuring method of claim 11 , wherein the substrate comprises silicon.

13 . The temperature measuring method of claim 11 , wherein the light has a wavelength between about 1100 nm and about 1400 nm.

14 . The temperature measuring method of claim 11 , wherein the light is provided by a superluminiscent diode (SLD).

15 . The temperature measuring method of claim 11 , wherein the first and second reflections are transmitted in an optical fiber to a photodetector, wherein, during propagation in the optical fiber, the first and second reflections are combined to form an interference signal.

16 . The temperature measuring method of claim 11 , further comprising repeating steps (a) to (d).

17 . The temperature measuring method of claim 11 , further comprising determining a temperature of two or more substrates disposed in the processing chamber.

18 . The temperature measuring method of claim 11 , further comprising simultaneously measuring the temperature at different locations of one or more substrates.

19 . The temperature measuring method of claim 11 , wherein the temperature of the substrate is measured in less than about 1 second.

20 . A non-transitory computer readable medium having instructions stored thereon that, when executed, cause a method measuring a temperature of a substrate, the method comprising:

irradiating a substrate inside a processing chamber with light;

receiving a first reflection of the light from a first surface of the substrate;

receiving a second reflection of the light through the substrate from an inner boundary of a second surface opposite the first surface; and

determining a substrate temperature based on a spectral analysis of an interference pattern of the first and second reflections.