Silicon wafer pre-alignment device and method therefor

Patent metadata

Field	Value
Publication number	US-10276418-B2
Application number	US-201415109040-A
Country	US
Kind code	B2
Filing date	Dec 26, 2014
Priority date	Dec 31, 2013
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

A wafer pre-alignment device is disclosed, including a first unit configured to drive a wafer to rotate or move upward or downward, a second unit configured to drive the wafer to translate, and a position detector including a light source, a lens and an image sensor. A light beam from the light source passes through the wafer and the lens and thereby provides information indicating a position of the wafer to the image sensor. The first unit and the second unit are able to adjust the position of the wafer based on the information obtained by the image sensor. A method for pre-aligning a TSV wafer is also disclosed.

First claim

What is claimed is:

1. A wafer pre-alignment device, comprising:
a first unit configured to drive a wafer to rotate or move upward or downward, the first unit comprising a first chuck for retaining the wafer;
a second unit configured to drive the wafer to translate relative to the first chuck;
a position detector comprising a light source, an image sensor disposed above the first chuck, and a lens disposed under the first chuck, wherein a light beam from the light source passes through the wafer, the first chuck and the lens and thereby provides information indicating a position of the wafer relative to the first chuck on to the image sensor,
wherein the first unit and the second unit are configured to adjust the position of the wafer relative to the first chuck based on the information obtained by the image sensor,
wherein the first unit further comprises: a rotating motor configured to drive the first chuck to rotate; and a lifting motor configured to drive the first chuck to move upward or downward, and
wherein the second unit comprises: a second chuck disposed lateral to the first chuck, wherein the lifting motor is configured to transfer the wafer between the first chuck and the second chuck; and a translating motor configured to drive the second chuck and the wafer to translate so as to adjust a radial position of the wafer relative to the first chuck.

2. The wafer pre-alignment device of claim 1 , wherein the information comprises a deviation of a center of the wafer from a center of the first chuck, and wherein the first unit and the second unit are configured to adjust a radial position of the wafer relative to the first chuck based on the deviation.

3. The wafer pre-alignment device of claim 1 , wherein each of the first chuck and the second chuck comprises a plurality of suction holes.

4. The wafer pre-alignment device of claim 1 , wherein the image sensor comprises a plurality of CCDs arranged in a one-dimensional linear array, an extended line of the one-dimensional linear array passes through a center of the first chuck.

5. The wafer pre-alignment device of claim 1 , wherein the position detector comprises a reflective optical system and/or a catadioptric optical system.

6. The wafer pre-alignment device of claim 5 , wherein the reflective optical system comprises the light source, a first lens assembly, the image sensor and the lens, the light source serving as a first light source for producing a light beam having a first wavelength, the lens implemented as a reflective lens for reflecting the light beam having the first wavelength, the first lens assembly disposed above the first chuck and under the image sensor and configured to direct the light beam having the first wavelength on the wafer and the reflective lens and the light beam is then reflected onto the image sensor.

7. The wafer pre-alignment device of claim 5 , wherein the catadioptric optical system comprises the light source, a second lens assembly, the image sensor and the lens, the light source serving as a second light source for producing a light beam having a second wavelength, the lens implemented as a transmissive lens allowing the transmission of the light beam having the second wavelength, the second lens assembly disposed under the first chuck and configured to cause the light beam having the second wavelength to transmit through the wafer and the transmissive lens and then reach the image sensor.

8. The wafer pre-alignment device of claim 5 , wherein the lens is a filtering lens configured to reflect a light beam having a first wavelength and allow transmission of a light beam having a second wavelength.

9. The wafer pre-alignment device of claim 5 , wherein: the wafer is a TSV wafer with a notch on an edge thereof, a warped wafer, an ultra-thin wafer or a Taiko wafer; the catadioptric optical system is configured to obtain the information indicating the position of the ultra-thin wafer or the Taiko wafer relative to the first chuck; and the reflective optical system is configured to obtain the information indicating the position of the TSV wafer relative to the first chuck.

10. The wafer pre-alignment device of claim 9 , wherein the information further comprises a position of the notch with respect to the TSV wafer and a position of the notch with respect to the first chuck, and wherein the first unit is further configured to adjust a circumferential position of the TSV wafer relative to the first chuck based on the information.

11. A method for pre-aligning the TSV wafer using the wafer pre-alignment device as defined in claim 10 , comprising the steps of:
a) retaining the TSV wafer on the first chuck by suction and irradiating the edge of the TSV wafer with a light beam produced by a first light source;
b) rotating the first chuck by 360 degrees, concurrently with the image sensor capturing an edge image of the TSV wafer retained on the first chuck and calculating a deviation of a center of the TSV wafer from the center of the first chuck;
c) transferring the TSV wafer from the first unit to the second unit and moving the TSV wafer by the second unit based on the calculated deviation so as to align the center of the TSV wafer with the center of the first chuck;
d) transferring the TSV wafer from the second unit back to the first unit, rotating the first chuck by 360 degrees, capturing an edge image of the TSV wafer on the first chuck and determining whether a deviation of the center of the TSV wafer from the center of the first chuck is smaller than a predetermined value by the image sensor, if yes, proceeding to step e and, if not, looping back to step c; and
e) performing, by the image sensor, detailed scanning of the notch in the TSV wafer to obtain an edge image of the notch, extracting edge coordinates of the notch from the edge image of the notch, and identifying positional attributes of the notch, thereby ending an orientation process.

12. The method of claim 11 , wherein the calculating the deviation of the center of the TSV wafer from the center of the first chuck comprises:
b1) obtaining a two-dimensional edge image of the TSV wafer by the image sensor and extracting edge coordinates of the TSV wafer from the obtained two-dimensional edge image of the TSV wafer;
b2) converting the edge coordinates of the TSV wafer to coordinates in a coordinate system of the first chuck;
b3) determining coordinates of the center of the TSV wafer in the coordinate system of the first chuck using a method of least squares; and
b4) calculating a difference between the coordinates of the center of the TSV wafer and coordinates of the center of the first chuck.

13. The method of claim 12 , wherein in step b1, the image sensor is a linear-array CCD image sensor which captures one-dimensional edge images of the TSV wafer, and the captured one-dimensional edge images are combined by software into the two-dimensional edge image of the TSV wafer.

14. The method of claim 11 , wherein step b further comprises: determining a type of the TSV wafer based on the edge image of the TSV wafer and determining a light intensity for the first light source based on the determined type of the TSV wafer.

15. The method of claim 11 , wherein in step e, the detailed scanning comprises the steps of:
e1) causing the first chuck to return to an original position with the notch in the TSV wafer situated under and counterclockwise to the image sensor;
e2) rotating the first chuck clockwise by an angle such that the notch in the TSV wafer completely passes by the image sensor, with the image sensor capturing one-dimensional images of the notch;
e3) fitting

Assignees

• Shanghai Microelectronics Equi
• Shanghai Micro Electronics Equipment Group Co Ltd

Inventors

• Sun Weiwang
• Wang Gang
• Huang Chunxia
• Hu Songli
• Jiang Jie
• Lu Ruzhan
• Mou Jiyuan

Classifications

• H10P74/232

  comprising connection or disconnection of parts of a device in response to a measurement · CPC title

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P72/7624

  characterised by the mechanical construction of the susceptor, stage or support · CPC title

• H10P72/7618

  characterised by a movable susceptor, stage or support, others than those only rotating on their own vertical axis, e.g. susceptors on a rotating carrousel · CPC title

• H10P72/78

  using vacuum or suction, e.g. Bernoulli chucks · CPC title