EPI self-heating sensor tube as in-situ growth rate sensor
A method and apparatus for determining a growth rate on a semiconductor substrate is described herein. The apparatus is an optical sensor, such as an optical growth rate sensor. The optical sensor is positioned in an exhaust of a deposition chamber. The optical sensor is self-heated using one or more internal heating elements, such as a resistive heating element. The internal heating elements are configured to heat a sensor coupon. A film is formed on the sensor coupon by exhaust gases flowed through the exhaust and is correlated to film growth on a substrate within a process volume of the deposition chamber.
1. A growth rate sensor suitable for use during semiconductor substrate manufacturing, the growth rate sensor comprising:
a body;
an optically transparent window disposed at an end of the body;
a silicon containing coupon disposed inside of the body and adjacent to a first side of the optically transparent window;
a resistive heating element disposed within the body and adjacent to a second side of the optically transparent window;
a radiation sensor; and
an optical fiber disposed between the radiation sensor and the optically transparent window, wherein the optically transparent window is positioned in between the silicon containing coupon and the resistive heating element.
2. The growth rate sensor of claim 1 , wherein the body further comprises:
an outer body; and
an optically transparent inner body, wherein the optically transparent window is part of the optically transparent inner body.
3. The growth rate sensor of claim 1 , further comprising a radiation source configured to emit radiation which passes through or reflects off of the silicon containing coupon and is measured by the radiation sensor.
4. The growth rate sensor of claim 1 , further comprising one or more of a mirror or a lens disposed between the radiation sensor and the optically transparent window.
5. The growth rate sensor of claim 1 , further comprising a thermocouple adjacent to the resistive heating element.
6. The growth rate sensor of claim 1 , further comprising a cover which partially surrounds the silicon containing coupon and secures the silicon containing coupon.
7. The growth rate sensor of claim 6 , wherein a plenum is disposed between the optically transparent window and the silicon containing coupon.
8. The growth rate sensor of claim 7 , wherein one or more equalization ports is disposed between an outside surface of the body and the plenum to allow pressure equalization between the plenum and a surrounding volume.
9. The growth rate sensor of claim 1 , wherein the silicon containing coupon is a silicon carbide substrate.
10. An exhaust assembly suitable for use during semiconductor substrate manufacturing, the exhaust assembly comprising:
one or more exhaust passage bodies;
an exhaust collector disposed at a distal end of the one or more exhaust passage bodies;
a growth rate sensor disposed within the exhaust collector and comprising:
a body;
an optically transparent window disposed at an end of the body;
a silicon containing coupon disposed inside of the body and adjacent to a first side of the optically transparent window;
a resistive heating element disposed within the body and adjacent to a second side of the optically transparent window;
a radiation sensor; and
an optical fiber disposed between the radiation sensor and the optically transparent window, wherein the optically transparent window is between the silicon containing coupon and the resistive heating element.
11. The exhaust assembly of claim 10 , further comprising an exhaust conduit coupled to the exhaust collector.
12. The exhaust assembly of claim 11 , wherein the growth rate sensor is disposed on an inside upper surface of the exhaust collector.
13. The exhaust assembly of claim 12 , wherein a radiation source is disposed through an inside lower surface of the exhaust collector and configured to emit radiation towards the silicon containing coupon.
14. The exhaust assembly of claim 11 , wherein the growth rate sensor is disposed on an inside lower surface of the exhaust collector.
15. The exhaust assembly of claim 14 , wherein a radiation source is disposed through an inside upper surface of the exhaust collector and configured to emit radiation towards the silicon containing coupon.
16. The exhaust assembly of claim 10 , wherein the silicon containing coupon is exposed to an exhaust volume within the exhaust collector.
17. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause a system to:
monitor an intensity of radiation reflected by or transmitted through a growth rate sensor, the growth rate sensor comprising:
a body:
an optically transparent window disposed at an end of the body;
a silicon containing coupon disposed inside of the body and adjacent to a first side of the optically transparent window;
a resistive heating element disposed within the body and adjacent to a second side of the optically transparent window;
a radiation sensor; and
an optical fiber disposed between the radiation sensor and the optically transparent window, wherein the optically transparent window is between the silicon containing coupon and the resistive heating element;
heat the silicon containing coupon using the resistive heating element during the monitoring of the intensity of the radiation; and
determine a growth rate of a film deposited onto the silicon containing coupon from the change in the intensity of the radiation.
18. The medium of claim 17 , wherein the growth rate sensor is positioned in an exhaust volume of a process chamber.
19. The medium of claim 18 , wherein the growth rate of the film deposited onto the silicon containing coupon is correlated to a growth rate on a substrate within a processing volume of the process chamber.
20. The growth rate sensor of claim 1 , wherein the first side of the optically transparent window is opposite the second side of the optically transparent window.