Non-invasive wafer transfer position diagnosis and calibration

• US 20030227624A1
• Filed: 06/07/2002
• Published: 12/11/2003
• Est. Priority Date: 06/07/2002
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Wu, Yu-Yi, Chen, Kun-Ei, Lin, San-Ching
• Granted Patent: US 6,965,432 B2
• Time in Patent Office: Days
• US Class Current: 356/400
• CPC Class Codes: G03F 7/7075 Handling workpieces outside exposure position, e.g. SMIF box
• CPC Class Codes: H01L 21/67259 Position monitoring, e.g. misposition detection or presence detection
• CPC Class Codes: H01L 21/681 using optical controlling means

Abstract

An apparatus and method for detecting mispositioned wafers attributable to transfer shift of the wafer are disclosed. A calibration wafer has a target region comprising a pattern of optically distinguishable features from which is determined the position of the calibration wafer within the chamber subsequent to its transfer therein. Preferably, the features comprise a pattern of colors that can be detected by spectroscopy. A preferred form and manner of providing such color features is by way of dielectric thin film filters.

Claims

1. Wafer position calibration apparatus for a process chamber comprising:

a calibration wafer placed within the process chamber, said calibration wafer including features thereon having known orientations to the calibration wafer; and

,

a detector effective to optically recognize said features and determine therefrom the position of the calibration wafer within the process chamber.

2. The wafer position calibration apparatus as claimed in claim 1 wherein said features comprise regions characterized by respective reflective wavelengths.

3. The wafer position calibration apparatus as claimed in claim 2 wherein said features comprise thin film interference filters.

4. The wafer position calibration apparatus as claimed in claim 1 wherein said features comprise regions characterized by respective reliefs.

5. The wafer position calibration apparatus as claimed in claim 3 wherein said features define a pattern that is centrally oriented with respect to the calibration wafer.

6. The wafer position calibration apparatus as claimed in claim 5 wherein said pattern comprises a checkerboard pattern.

7. The wafer position calibration apparatus as claimed in claim 5 wherein said pattern comprises a first region substantially centrally oriented with respect to the calibration wafer and a second region perimetrically bounding said first region.

8. The wafer position calibration apparatus as claimed in any claim 3 wherein the detector discriminates reflective spectrum.

9. The wafer position calibration apparatus as claimed in claim 8 wherein the detector comprises a spectroscopic interferometer.

10. The wafer position calibration apparatus as claimed in claim 8 wherein the detector includes a broad band light source.

11. A calibration wafer for use in a process chamber, said chamber including a spectroscope and associated broad band light source, the calibration wafer comprising:

a first region within a larger target region, said first region substantially coincident with the center of said calibration wafer and characterized by a reflective wavelength discernibly different from any other reflective wavelength associated with the target region.

12. The calibration wafer as claimed in claim 11 further comprising a second region within said target region perimetrically bounding said first region.

13. The calibration wafer as claimed in claim 12 wherein the second region comprises a plurality of sub-regions, each of said plurality of sub-regions characterized by respective reflective wavelengths discernibly different from any other reflective wavelength associated with the target region.

14. The calibration wafer as claimed in claim 13 wherein the sub-regions are concentrically distributed.

15. The calibration wafer as claimed in claim 13 wherein the sub-regions are perimetrically distributed.

16. The calibration wafer as claimed in claim 11 wherein the sub-regions are further divided perimetrically.

17. The calibration wafer as claimed in claim 11 wherein said regions comprise dielectric thin film filters.

18. Method of wafer transfer calibration in a process chamber comprising the steps:

providing a calibration wafer characterized by features thereon having known orientations to the calibration wafer;

robotically transferring into the chamber a calibration wafer;

from outside of the chamber, optically detecting the features on the calibration wafer;

relating the detected features to a predetermined mapping of said features relative to the calibration wafer; and

,

determining from said related features and mapping of said features the position of the calibration wafer in the chamber.

19. The method of wafer transfer calibration in a process chamber as claimed in claim 18 wherein the features comprise different colors and optically detecting the features comprises spectroscopy.

20. The method of wafer transfer calibration in a process chamber as claimed in claim 18 wherein the step of transferring comprises prealigning the calibration wafer.