Substrate positioning apparatus and methods

1. A substrate processing apparatus comprising:

a chamber;

a substrate support configured to support a substrate comprising a top surface and a bottom surface defining a substrate thickness, the substrate support configured to rotate the substrate 360 degrees through a plurality of rotational angular positions within the chamber;

a laser positioned to direct a radiation beam along the thickness between the top surface and the bottom surface;

a sensor positioned opposite the laser to detect radiation transmitted along the thickness of the substrate between the top surface and the bottom surface; and

a controller configured to analyze a signal strength of the radiation detected by the sensor at the plurality of rotational angular positions and to correlate the signal strength at the plurality of rotational angular positions to a position within the chamber.

2. The substrate processing apparatus of claim 1 , wherein the controller is configured to analyze the signal strength of the radiation transmitted along the thickness of a polygonal substrate at the plurality of rotational angular positions.

3. The substrate processing apparatus of claim 2 , wherein the controller is configured to analyze the signal strength transmitted along the thickness of a rectangular substrate.

4. The substrate processing apparatus of claim 3 , wherein the controller is configured to analyze a signal strength pattern versus a rotational angular position.

5. The substrate processing apparatus of claim 4 , wherein the sensor comprises a laser sensor.

6. The substrate processing apparatus of claim 5 , wherein the controller controls rotational movement of the substrate support.

7. The substrate processing apparatus of claim 6 , wherein the controller comprises a memory to record a signal strength at a plurality of rotational angular positions.

8. The substrate processing apparatus of claim 7 , wherein the controller is configured to generate a signal strength pattern at the plurality of rotational angular positions.

9. The substrate processing apparatus of claim 8 , wherein the controller is configured to compare the signal strength pattern to a pre-determined signal strength pattern.

10. The substrate processing apparatus of claim 9 , wherein the pre-determined signal strength pattern correlates to the substrate being centered on the substrate support.

11. The substrate processing apparatus of claim 10 , wherein the controller is configured to reposition the substrate.

12. An extreme ultraviolet (EUV) mask production system comprising:

a holding chamber to provide access to a substrate handling vacuum chamber including a plurality of ports to provide access to a vacuum chamber including, a physical vapor deposition chamber, a pre-clean chamber, and a multi-cathode PVD chamber;

an EUV mask blank loading system configured to load an EUV mask blank comprising a top surface and a bottom surface defining an EUV mask blank thickness, in at least one of the holding chamber and the vacuum chamber;

a substrate support configured to support and rotate the EUV mask blank 360 degrees through a plurality of rotational angular positions within at least one of the holding chamber and the vacuum chamber;

a laser positioned to direct a radiation beam along the thickness between the top surface and the bottom surface;

a sensor positioned opposite the laser to detect radiation transmitted along the thickness of the substrate between the top surface and the bottom surface; and

a controller configured to analyze a signal strength of the radiation detected by the sensor at the plurality of rotational angular positions and to correlate the signal strength at the plurality of rotational angular positions to a position within the vacuum chamber.

13. The EUV mask production system of claim 12 , wherein the controller is configured to analyze the signal strength transmitted along the thickness of a rectangular substrate and to analyze a signal strength pattern versus the plurality of rotational angular positions.

14. The EUV mask production system of claim 13 , wherein the controller controls rotational movement of the substrate support, compare the signal strength pattern to a pre-determined signal strength pattern and to reposition the substrate.

15. A method of positioning a substrate in a chamber comprising:

placing a rectangular substrate in a chamber on a substrate support, the substrate comprising a top surface and a bottom surface defining a substrate thickness;

rotating the substrate 360 degrees through a plurality of rotational angular positions within the chamber;

directing a laser to direct a radiation beam along the thickness between the top surface and the bottom surface;

detecting radiation from the radiation beam transmitted along the thickness of the substrate between the top surface and the bottom surface; and

analyzing a signal strength of the radiation detected at the plurality of rotational angular positions and correlating the signal strength at the plurality of rotational angular positions to a position within the chamber.

16. The method of claim 15 , further comprising using a controller to generate a signal strength pattern at the plurality of rotational angular positions.

17. The method of claim 16 , further comprising comparing the signal strength pattern to a pre-determined signal strength pattern.

18. The method of claim 17 , wherein the pre-determined signal strength pattern correlates to the substrate being at a center position on the substrate support.

19. The method of claim 18 , further comprising repositioning the substrate in the chamber to a center position.

20. The method of claim 19 , further comprising using a robot arm to reposition the substrate.