Wafer Orientation Sensor

• US 20120327428A1
• Filed: 06/27/2011
• Published: 12/27/2012
• Est. Priority Date: 06/27/2011
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hellwig, Juergen, Goetz, Stefan
• Granted Patent: US 8,614,797 B2
• Time in Patent Office: Days
• US Class Current: 356/614
• CPC Class Codes: G01B 11/272 using photoelectric detection means
• CPC Class Codes: H01L 21/681 using optical controlling means

Abstract

A wafer orientation sensor includes a laser source, a laser detector, and an evaluator. The laser source is configured to emit a laser beam in a direction of a wafer in an evaluation region of the wafer orientation sensor so that the laser beam is reflected at a main surface of the wafer resulting in a reflected laser beam. The laser detector is configured to receive the reflected laser beam at least when the wafer is within a tolerance range regarding the orientation of the wafer. The evaluator is configured to receive a beam reception information from the laser detector and to determine an orientation information based on the beam reception information.

Claims

1. A wafer orientation sensor, comprising:

a laser source configured to emit a laser beam in a direction of a wafer in an evaluation region of the wafer orientation sensor so that the laser beam is reflected at a main surface of the wafer resulting in a reflected laser beam;

a laser detector configured to receive the reflected laser beam at least when the wafer is within a tolerance range; and

an evaluator configured to receive beam reception information from the laser detector and to determine wafer orientation information based on the beam reception information.

2. The wafer orientation sensor according to claim 1,

wherein the evaluator comprises a distance measuring unit configured to determine a total path length of the laser beam and the reflected laser beam on the basis of the beam reception information to determine the orientation information as a function of the total path length.

3. The wafer orientation sensor according to claim 1, further comprising:

a second laser source and a third laser source configured to emit a second laser beam and a third laser beam towards the wafer in the evaluation region so that the second laser beam and the third laser beam are reflected at the main surface of the wafer resulting in a second reflected laser beam and a third reflected laser beam, respectively, wherein the laser beam, the second laser beam and the third laser beam are reflected at different locations of the main surface;

a second laser detector and a third laser detector configured to receive the second reflected laser beam and the third reflected laser beam at least when the wafer is within the tolerance range;

wherein the evaluator is further configured to receive second beam reception information from the second laser detector and third beam reception information from the third laser detector and comprises a distance measuring unit configured to determine, on the basis of the beam reception information, the second beam reception information and the third beam reception information, a total path length of the laser beam and the reflected laser beam, a second total path length of the second laser beam and the second reflected laser beam, and a third total path length of the third laser beam and the third reflected laser beam, and configured to determine the orientation information as functions of the total path length, the second total path length, and the third total path length.

4. The wafer orientation sensor according to claim 3,

wherein the evaluator further comprises comparators configured to compare the total path length, the second total path length, and the third total path length with corresponding allowable ranges resulting in corresponding comparison results and to determine the orientation information as a Boolean combination of the comparison results, the orientation information indicating whether the orientation of the wafer is within an allowable orientation range.

5. The wafer orientation sensor according to claim 3,

wherein the evaluator is further configured to determine a wafer plane on the basis of the total path length, the second total path length, and the third total path length and to compare the wafer plane with a desired wafer plane and to derive the wafer orientation information from the determined wafer plane.

6. The wafer orientation sensor according to claim 3, further comprising a rack to which the laser source, the second laser source, the third laser source, the laser detector, the second laser detector, and the third laser detector are mounted.

7. The wafer orientation sensor according to claim 1, wherein the laser beam is reflected within an edge region of the main surface of the wafer when the wafer is within the tolerance range regarding the orientation of the wafer.

8. The wafer orientation sensor according to claim 1, wherein the laser source and the laser detector are adjacent to each other.

9. The wafer orientation sensor according to claim 1, wherein the laser beam hits the wafer at an angle different than 90°

when the wafer is approximately in a desired orientation.

10. The wafer orientation sensor according to claim 1, further comprising a wafer orientation signal output configured to provide the orientation information in the form of an enable signal to a wafer processing control system.

11. A wafer orientation sensor comprising:

a laser distance measuring device configured to measure a distance to a main surface of a wafer by emitting a laser beam and receiving a reflected laser beam when the wafer is placed in an evaluation region of the wafer orientation sensor;

a comparator configured to compare the measured distance with a threshold distance value and to generate a comparison result; and

a logic circuit configured to determine an orientation information on the basis of the comparison result.

12. The wafer orientation sensor according to claim 11, further comprising:

a second laser distance measuring device and a third laser distance measuring device configured to measure distances to the main surface of the wafer by means of emitting a second laser beam and a third laser beam and receiving a second reflected laser beam and a third reflected laser beam when the wafer is placed in the evaluation region of the wafer orientation sensor, wherein the laser distance measuring device, the second laser distance measuring device and the third laser distance measuring device aim at different locations of the main surface;

a second comparator configured to compare a second distance determined by the second laser distance measuring device with a second threshold value and to generate a second comparison result;

a third comparator configured to compare a third distance determined by the third laser distance measuring device with a third threshold value and to generate a third comparison result;

wherein the logic circuit is configured to determine the orientation information on the basis of the comparison result, the second comparison result and the third comparison result.

13. The wafer orientation sensor according to claim 12, further comprising a rack to which the laser distance measuring device, the second laser distance measuring device, the third laser distance measuring device, the comparator, the second comparator, and the third comparator are mounted.

14. The wafer orientation sensor according to claim 11,

wherein the laser beam is reflected within an edge region of the main surface of the wafer when the wafer is within a tolerance range regarding an orientation of the wafer.

15. The wafer orientation sensor according to claim 11,

wherein the laser beam hits the wafer at an angle different than 90°

when the wafer is approximately in a desired orientation.

16. The wafer orientation sensor according to claim 11, further comprising a wafer orientation signal output configured to provide the orientation information in the form of an enable signal to a wafer processing control system.

17. A wafer orientation sensor comprising:

a means for measuring a distance to a main surface of a wafer via an emission of a laser beam and a reception of a corresponding reflected laser beam, when the wafer is placed in an evaluation region of the wafer orientation sensor;

a means for comparing a distance measure generated by the means for measuring a distance with a threshold distance value and to generate a comparison result; and

a means for determining an orientation information on the basis of the comparison result.

18. A method for determining an orientation of a wafer during a processing of the wafer, the method comprising:

emitting a laser beam in a direction of the wafer within an evaluation area so that the laser beam is reflected at a main surface of the wafer resulting in a reflected laser beam;

receiving the reflected laser beam and deriving beam reception information therefrom;

determining an orientation information based on the beam reception information; and

performing the processing of the wafer.

19. The method according to claim 18, further comprising:

determining a total path length of the laser beam and the reflected laser beam on the basis of the beam reception information;

wherein determining the orientation information comprises taking into account the total path length so that the orientation information is a function of the total path length.

20. The method according to claim 18, further comprising:

emitting a second laser beam and a third laser beam in the direction of the wafer so that the laser beam, the second laser beam and the third laser beam are reflected at different locations of the main surface of the wafer and result in the reflected laser beam, a second reflected laser beam and a third reflected laser beam;

receiving the second reflected laser beam and the third reflected laser beam and deriving second beam reception information and third beam reception information therefrom;

wherein determining the orientation information comprises;

determining a total path length of the laser beam and the reflected laser beam, a second total path length of the second laser beam and the second reflected laser beam, and a third total path length of the third laser beam and the third reflected laser beam, and

determining the orientation information as functions of the total path length, the second total path length, and the third total path length.

21. The method according to claim 20, wherein the determining of the orientation

comparing the total path length, the second total path length, and the third total path length with corresponding allowable ranges resulting in corresponding comparison results;

and

determining the orientation information as a Boolean combination of the comparison results, the orientation information indicating whether the orientation of the wafer is within an allowable orientation range.

22. The method according to claim 20, wherein the determining of the orientation information comprises:

determining a wafer plane on the basis of the total path length, the second total path length, and the third total path length and to compare the wafer plane with a desired wafer plane and to derive the orientation information from the determined wafer plane.

23. The method according to claim 18, wherein the laser beam is reflected within an edge region of the main surface of the wafer when the wafer is within a tolerance range regarding the orientation of the wafer.

24. The method according to claim 18, wherein the laser beam hits the wafer at an angle different from 90°

when the wafer is approximately in a desired orientation.

25. The method according to claim 18, further comprising outputting a wafer orientation signal output configured to provide the orientation information in a form of an enable signal to a wafer processing control system.

26. The method according to claim 18, wherein the processing of the wafer comprises electroplating portions of the wafer.

27. A method for checking an orientation of a wafer during a processing of the wafer, the method comprising:

measuring a distance to a particular location on a main surface of the wafer by emitting a laser beam and receiving a corresponding reflected laser beam;

comparing the distance with a threshold distance to obtain a comparison result;

determining an orientation information on the basis of the comparison result; and

performing the processing of the wafer.