Apparatus for Detecting a Pre-Aligning Element at a Wafer

• US 20150009498A1
• Filed: 07/05/2013
• Published: 01/08/2015
• Est. Priority Date: 07/05/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Kittner, Horst, Zell, Thomas
• Granted Patent: US 9,476,701 B2
• Time in Patent Office: Days
• US Class Current: 356/399
• CPC Class Codes: G01B 11/27 for testing the alignment of axes means for centering or aligning a light guide within a ferrule G02B6/3834
• CPC Class Codes: G01B 11/272 using photoelectric detection means
• CPC Class Codes: H01L 21/681 using optical controlling means
• CPC Class Codes: H01L 2223/54426 for alignment
• CPC Class Codes: H01L 23/544 Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps test patterns for characterising or monitoring manufacturing processes H01L22/00

Abstract

An apparatus detects a pre-aligning element at a wafer. The wafer has the pre-aligning element at a wafer edge. The apparatus includes a sensor arrangement and an evaluation unit. The sensor arrangement is configured to illuminate subsequent edge portions of the wafer edge, to receive transmitted fractions and reflected fractions of the illumination from the illuminated edge portions with an illumination sensor, and to output a first and a second sensor signal. The first sensor signal is based on the transmitted fractions of the illumination and the second sensor signal is based on the reflected fractions of the illumination. The evaluation unit is configured to evaluate the first sensor signal and to determine a first position information with respect to a coarse position of the pre-aligning element if the first sensor signal indicates that the transmitted fractions of the illumination has reached a predetermined threshold value.

Claims

1. Apparatus for detecting a pre-aligning element at a wafer, the wafer having the pre-aligning element at a wafer edge, the apparatus comprising:

a sensor arrangement configured to illuminate subsequent edge portions of the wafer edge, to receive transmitted fractions and reflected fractions of the illumination from the illuminated edge portions, and to output a first and a second sensor signal, wherein the first sensor signal is based on the transmitted fractions of the illumination and the second sensor signal is based on the reflected fractions of the illumination; and

an evaluation unit configured to evaluate the first sensor signal and to determine a first position information indicating a coarse position of the pre-aligning element, when the first sensor signal indicates that the transmitted fractions of the illumination have reached a predetermined threshold value, wherein the first position information indicates that the pre-aligning element is at least partially located within the currently evaluated edge portion, and, after having determined the first position information, to determine a second position information based on the second sensor signal and the first position information, wherein the second position information indicates the fine position of the pre-aligning element.

2. Apparatus according to claim 1, wherein the sensor arrangement comprises a first illumination sensor configured to sense the transmitted fractions of the illumination, a second illumination sensor configured to sense the reflected fractions of the illumination, and an illumination source configured to illuminate the subsequent edge portions of the wafer edge, wherein the illumination source and the second illumination sensor are arranged on the same side of the wafer, and wherein the first illumination sensor is arranged at the opposing side of the wafer.

3. Apparatus according to claim 1, wherein the sensor arrangement comprises an illumination sensor configured to sense the transmitted fractions and the reflected fractions of the illumination, a first illumination source configured to illuminate the wafer edge for creating the transmitted fractions of the illumination and a second illumination source configured to illuminate the wafer edge for creating the reflected fractions of the illumination, wherein the second illumination source and the illumination sensor are arranged at the same side of the wafer, and wherein the first illumination source is arranged at the opposing side of the wafer.

4. Apparatus according to claim 1, wherein the sensor arrangement comprises a first illumination sensor configured to sense the transmitted fractions of the illumination, a second illumination sensor configured to sense the reflected fractions of the illumination, a first illumination source configured to illuminate the wafer edge for creating the transmitted fractions of the illumination and a second illumination source configured to illuminate the wafer edge for creating the reflected fractions of the illumination, wherein the first and the second illumination sensor are arranged at the same side of the wafer and wherein the first illumination source is arranged at one side of the wafer and the second illumination source is arranged at the opposing side of the wafer.

5. Apparatus according to claim 1, wherein the apparatus is configured to detect the pre-aligning element in form of a notch or a flat at the wafer edge.

6. Apparatus according to claim 1, wherein the first position information indicates the position of the pre-alignment element within a first range of detection, and wherein the second position information indicates the position of the pre-alignment element within a second range of detection, wherein the second range of detection is equal or smaller than the first range of detection.

7. Pre-alignment system, comprising:

an apparatus according to claim 1, further comprising

an actuator configured to move the wafer into a pre-alignment position; and

a control unit configured to control the actuator for pre-aligning the wafer based on the first and second position information.

8. Pre-alignment system according to claim 7, wherein

the sensor arrangement comprises a first illumination sensor configured to sense the transmitted fractions of the illumination, a second illumination sensor configured to sense the reflected fractions of the illumination, and an illumination source configured to illuminate the subsequent edge portions of the wafer edge, wherein the illumination source and the second illumination sensor are arranged on the same side of the wafer, and wherein the first illumination sensor is arranged at the opposing side of the wafer.

9. Pre-alignment system according to claim 7, wherein

the sensor arrangement comprises an illumination sensor configured to sense the transmitted fractions and the reflected fractions of the illumination, a first illumination source configured to illuminate the wafer edge for creating the transmitted fractions of the illumination and a second illumination source configured to illuminate the wafer edge for creating the reflected fractions of the illumination, wherein the second illumination source and the illumination sensor are arranged at the same side of the wafer, and wherein the first illumination source is arranged at the opposing side of the wafer.

10. Pre-alignment system according to claim 7, wherein

the sensor arrangement comprises a first illumination sensor configured to sense the transmitted fractions of the illumination, a second illumination sensor configured to sense the reflected fractions of the illumination, a first illumination source configured to illuminate the wafer edge for creating the transmitted fractions of the illumination and a second illumination source configured to illuminate the wafer edge for creating the reflected fractions of the illumination, wherein the first and the second illumination sensor are arranged at the same side of the wafer and wherein the first illumination source is arranged at one side of the wafer and the second illumination source is arranged at the opposing side of the wafer.

11. Pre-alignment system according to claim 7, wherein the first position information indicates the position of the pre-alignment element within a first range of detection, and wherein the second position information indicates the position of the pre-alignment element within a second range of detection, wherein the second range of detection is equal or smaller than the first range of detection.

12. Method for detecting a pre-aligning element at a wafer, the wafer having the pre-aligning element at a wafer edge, the method comprising:

illuminating subsequent edge portions of the wafer edge with a sensor arrangement, receiving transmitted fractions and reflected fractions of the illumination from the illuminated edge portion with an illumination sensor, and outputting a first and a second sensor signal, wherein the first sensor signal is based on the transmitted fractions of the illumination and the second sensor signal is based on the reflected fractions of the illumination; and

evaluating the first sensor signal with an evaluation unit and determining a first position information with respect to a coarse position of the pre-aligning element if the first sensor signal indicates that the transmitted fractions of the illumination have reached a predetermined threshold value, wherein the first position information indicates that the pre-aligning element is at least partially located within the currently evaluated edge portion, and, after having determined the first position information, determining a second position information based on the second sensor signal and the first position information, wherein the second position information indicates the fine position of the pre-aligning element.

13. Method according to claim 12, wherein

the transmitted fractions of the illumination are received with a first illumination sensor and the reflected fractions of the illumination sensor are received with a second illumination sensor;

and wherein

the subsequent edge portions are illuminated with an illumination source.

14. Method according to claim 12, wherein

the transmitted and the reflected fractions of the illumination are received with an illumination sensor;

and wherein

the subsequent edge portions are illuminated with a first illumination source for creating the transmitted fractions of the illumination and a second illumination source for creating the reflected fractions of the illumination.

15. Method according to claim 12, wherein

the transmitted fractions of the illumination are received with a first illumination sensor and the reflected fractions of the illumination sensor are received with a second illumination sensor;

and wherein

the subsequent edge portions are illuminated with a first illumination source for creating the transmitted fractions of the illumination and a second illumination source for creating the reflected fractions of the illumination.

16. Method according to claim 12, further comprising

detecting the pre-aligning element in form of a notch or a flat at the wafer edge.

17. Method for pre-aligning a wafer, comprising:

detecting a pre-aligning element at a wafer according to claim 12

controlling an actuator based on the first and second position information for moving the wafer into a pre-alignment position with the actuator.

18. Non transitory storage medium having stored thereon a computer program having a program code for performing, when running on a computer, a method for detecting a pre-aligning element at a wafer, the wafer having the pre-aligning element at a wafer edge, the method comprising:

illuminating subsequent edge portions of the wafer edge with a sensor arrangement, receiving transmitted fractions and reflected fractions of the illumination from the illuminated edge portion with an illumination sensor, and outputting a first and a second sensor signal, wherein the first sensor signal is based on the transmitted fractions of the illumination and the second sensor signal is based on the reflected fractions of the illumination; and

evaluating the first sensor signal with an evaluation unit and determining a first position information with respect to a coarse position of the pre-aligning element if the first sensor signal indicates that the transmitted fractions of the illumination have reached a predetermined threshold value, wherein the first position information indicates that the pre-aligning element is at least partially located within the currently evaluated edge portion, and, after having determined the first position information, determining a second position information based on the second sensor signal and the first position information, wherein the second position information indicates the fine position of the pre-aligning element.