Wafer aligning apparatus and related method

Abstract

Embodiments of the invention provide a wafer aligning apparatus and a wafer aligning method. In one embodiment, the wafer aligning apparatus comprises an imaging unit adapted to take an image of a wafer being transferred from a load lock chamber to a transfer chamber and adapted to convert the image into digital signals, and a signal processing unit adapted to calculate a center alignment correction value for the wafer by comparing the digital signals to a master image stored in the signal processing unit. The wafer aligning apparatus further comprises a robot controller adapted to receive the center alignment correction value from the signal processing unit and adapted to control a transfer robot in accordance with the center alignment correction value to provide the wafer to a process chamber such that the center of the wafer is substantially aligned.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described herein with reference to the accompanying drawings, in which like reference symbols indicate like or similar elements throughout. In the drawings:

FIG. 1 is a plan view of a unit process apparatus comprising a wafer aligning apparatus in accordance with an embodiment of the invention;

FIG. 2 is a plan view showing a wafer being moved by a transfer robot in accordance with an embodiment of the invention;

FIG. 3 is a plan view illustrating a typical wafer;

FIG. 4 is a structural view showing a wafer aligning apparatus in accordance with an embodiment of the invention;

FIG. 5 is a flowchart showing a wafer aligning method in accordance with an embodiment of the invention;

FIG. 6 is a plan view showing a wafer image of a wafer that is being transferred and that is displaced horizontally, but not rotated, relative to a master image; and,

FIG. 7 is a plan view showing a wafer image of a wafer that is being transferred and that is displaced horizontally and rotated relative to a master image.

Claims

1. A wafer aligning apparatus comprising: an imaging unit adapted to take an image of a wafer being transferred from a load lock chamber to a transfer chamber and adapted to convert the image into digital signals;a signal processing unit adapted to calculate a center alignment correction value for the wafer by comparing the digital signals to a master image stored in the signal processing unit; and,a robot controller adapted to receive the center alignment correction value from the signal processing unit and adapted to control a transfer robot in accordance with the center alignment correction value to provide the wafer to a process chamber such that the center of the wafer is substantially aligned.

2. The wafer aligning apparatus of claim 1, wherein the imaging unit comprises a Charge-Coupled Device (CCD) camera.

3. The wafer aligning apparatus of claim 2, wherein the CCD camera is adapted to take the image in accordance with a trigger signal generated by a laser sensor.

4. The wafer aligning apparatus of claim 3, wherein the CCD camera takes the image after a predetermined amount of time has lapsed since the generation of the trigger signal.

5. The wafer aligning apparatus of claim 3, wherein the laser sensor is adapted to generate the trigger signal in accordance with a substantial change in an amount of reflected light detected by the laser sensor.

6. The wafer aligning apparatus of claim 2, wherein the laser sensor is adapted to generate a trigger signal in accordance with a substantial change in an amount of reflected light detected by the laser sensor.

7. The wafer aligning apparatus of claim 1; wherein the imaging unit is disposed on a window of a slit valve door module disposed between the load lock chamber and the transfer chamber.

8. A wafer aligning apparatus comprising: a laser sensor adapted to generate a trigger signal;an illuminator adapted to illuminate a wafer being transferred by a transfer robot from a cassette disposed in a load lock chamber to a transfer chamber, wherein the illuminator is adapted to illuminate the wafer in accordance with the trigger signal;a Charge-Coupled Device (CCD) camera adapted to take an image of the wafer in accordance with the trigger signal and adapted to convert the image into digital signals;a signal processing unit adapted to calculate a center alignment correction value for the wafer by comparing the digital signals to a master image stored in the signal processing unit; and,a robot controller adapted to receive the center alignment correction value from the signal processing unit and control movement of a transfer robot in accordance with the center alignment correction value.

9. The wafer aligning apparatus of claim 8, wherein the laser sensor is adapted to generate the trigger signal in accordance with a substantial change in an amount of reflected light detected by the laser sensor.

10. The wafer aligning apparatus of claim 9, wherein the substantial change in the amount of reflected light detected by the laser sensor occurs after a boundary between a robot arm of the transfer robot and a coupler of the transfer robot passes under the laser sensor, wherein the robot arm has a first color and the coupler has a second color different than the first color.

11. The wafer aligning apparatus of claim 8, wherein the laser sensor is disposed on a window of a slit valve door module disposed between the load lock chamber and the transfer chamber.

12. The wafer aligning apparatus of claim 8, wherein the illuminator comprises a flash lamp.

13. The wafer aligning apparatus of claim 8, wherein the illuminator is adapted to begin operating when the trigger signal is generated.

14. The wafer aligning apparatus of claim 8, wherein the illuminator is adapted to begin operating after a predetermined amount of time has lapsed since the generation of the trigger signal.

15. The wafer aligning apparatus of claim 8, wherein the illuminator is disposed on a window of a slit valve door module disposed between the load lock chamber and the transfer chamber.

16. The wafer aligning apparatus of claim 8, wherein the CCD camera is adapted to begin operating when the trigger signal is generated.

17. The wafer aligning apparatus of claim 8, wherein the CCD camera and the illuminator are adapted to begin operating simultaneously.

18. The wafer aligning apparatus of claim 8, wherein the CCD camera is adapted to begin operating after a predetermined amount of time has lapsed since the generation of the trigger signal.

19. The wafer aligning apparatus of claim 8, wherein the CCD camera is disposed on a window of a slit valve door module disposed between the load lock chamber and the transfer chamber.

20. The wafer aligning apparatus of claim 8, wherein the laser sensor, the illuminator, and the CCD camera are disposed on a window of a slit valve door module disposed between the load lock chamber and the transfer chamber.

21. A wafer aligning method for aligning a wafer using a wafer aligning apparatus, the wafer aligning apparatus comprising: a laser sensor adapted to generate a trigger signal;an illuminator adapted to illuminate a wafer being transferred by a transfer robot from a cassette disposed in a load lock chamber to a transfer chamber, wherein the illuminator is adapted to illuminate the wafer in accordance with the trigger signal;a Charge-Coupled Device (CCD) camera adapted to take an image of the wafer in accordance with the trigger signal and adapted to convert the image into digital signals;a signal processing unit adapted to calculate a center alignment correction value for the wafer by comparing the digital signals to a master imaged stored in the signal processing unit; and,a robot controller adapted to receive the center alignment correction value from the signal processing unit and control movement of the transfer robot in accordance with the center alignment correction value,the wafer aligning method comprising:withdrawing the wafer from the cassette using the transfer robot;generating the trigger signal using the laser sensor when the wafer is being transferred from the cassette disposed in the load lock chamber to the transfer chamber;taking an image of the wafer disposed on the transfer robot in accordance with the generation of the trigger signal;converting the image of the wafer into digital signals;detecting coordinates of a first apex of a flat zone of the wafer image, and detecting a flat zone angle of the wafer image;calculating a flat zone angle difference between respective flat zone angles of the wafer image and the master image by comparing the digital signals with the master image;calculating coordinates of a center of a wafer image;calculating a wafer center difference;comparing the wafer center difference to a stored first limit and comparing the flat zone angle difference to a stored second limit;if the wafer center difference exceeds the first limit or the flat zone angle difference exceeds the second limit: providing the wafer to an aligning chamber using the transfer robot, aligning the wafer, and providing the wafer to the process chamber as aligned; and,if the wafer center difference is below the first limit and the flat zone angle is below the second limit: calculating a center alignment correction value for the transfer robot in accordance with the wafer center difference; and,controlling the movement of the transfer robot in accordance with the center alignment correction value to load the wafer into the process chamber such that the center of the wafer is substantially aligned.

22. The wafer aligning method of claim 21, wherein the laser sensor is adapted to generate the trigger signal in accordance with a substantial change in an amount of light reflected from the transfer robot, as detected by the laser sensor.

23. The wafer aligning method of claim 21, wherein the substantial change in the amount of light reflected from the transfer robot occurs when a boundary between a robot arm of the transfer robot and a coupler of the transfer robot passes under the laser sensor, wherein the robot arm has a first color and the coupler has a second color different than the first color.

24. The wafer aligning method of claim 21, wherein taking an image of the wafer comprises illuminating the wafer using the illuminator.

25. The wafer aligning method of claim 21, wherein taking the image of the wafer is performed after a predetermined amount of time has lapsed since the generation of the trigger signal.

26. The wafer aligning method of claim 21, wherein the coordinates of the center of the wafer image are calculated in accordance with the following equations: Wx=−Sin(θ)×100+A; and,Wy=Cos(θ)×100+B, wherein (Wx, Wy) represents the center coordinate of the wafer image, θ is the flat zone angle difference between the respective flat zone angles of the wafer image and the master image, and (A, B) are the coordinates of the first apex of the wafer image.

27. The wafer aligning method of claim 21, wherein the wafer center (Wx, Wy) is calculated in accordance with the equations: Wx=−Sin(θ)×100+Δx+100; and,Wy=Cos(θ)×100+Δy, where Δx and Δy are displacement amounts of the wafer and θ is the flat zone angle difference between the respective flat zone angles of the wafer image and the master image.

28. The wafer aligning method of claim 21, wherein an apex of a flat zone of the master image is the origin of the coordinate system in which the coordinates of the center of the wafer image are calculated.