WAFER CENTER FINDING WITH CONTACT IMAGE SENSORS
A number of wafer center finding methods and systems are disclosed herein that improve upon existing techniques used in semiconductor manufacturing.
1 A device comprising:
an interior chamber having a plurality of entrances shaped and sized for passage of at least one wafer;
a contact image sensor positioned to scan a wafer within the interior;
a robot within the interior including an end effector for handling the wafer, the robot configured to move the wafer within a measurement volume of the contact image sensor thereby obtaining an image of at least a portion of the wafer; and
a processor configured to process the image and determine a center of the wafer.
2 . The device of claim 1 wherein the robot moves the wafer linearly through the measurement volume of the contact image sensor.
3 . The device of claim 2 wherein the contact image sensor is oriented normal to a path of the wafer.
4 . The device of claim 2 wherein the contact image sensor is oriented at a forty-five degree angle to a path of the wafer.
5 . The device of claim 1 wherein the robot moves the wafer in a curved path through the measurement volume of the contact image sensor.
6 . The device of claim 1 wherein the robot moves the wafer in a discontinuous path through the measurement volume of the contact image sensor.
7 . The device of claim 1 wherein the robot rotates the wafer within the measurement volume of the contact image sensor.
8 . The device of claim 7 wherein the robot is adapted to lift the wafer into the measurement volume of the contact image sensor.
9 . The device of claim 7 wherein the robot includes a rotating chuck on an end effector adapted to rotate the wafer.
10 . The device of claim 9 wherein the rotating chuck rotates between one-hundred eighty degrees and three-hundred sixty degrees.
11 . The device of claim 7 further comprising a rotating chuck adapted to lift the wafer from the end effector into the measurement volume of the contact image sensor.
12 . The device of claim 1 wherein the contact image sensor is at least 300 mm in length.
13 . The device of claim 1 wherein the contact image sensor has a length exceeding a diameter of the wafer.
14 . The device of claim 1 wherein the contact image sensor is positioned at one of the plurality of entrances to the interior.
15 . The device of claim 14 further comprising a plurality of contact image sensors, each one of the plurality of contact image sensors place at one of the plurality of entrances to the interior.
16 . The device of claim 1 wherein the contact image sensor is placed to intersect a center of the interior.
17 . The device of claim 1 further comprising a second contact image sensor, wherein the contact image sensor and the second contact image sensor are positioned collinearly.
18 . The device of claim 17 wherein the contact image sensor and the second contact image sensor are positioned at one of the plurality of entrances to the interior.
19 . The device of claim 18 further comprising a plurality of pairs of collinear contact image sensors positioned at each one of the plurality of entrances to the interior.
20 . The device of claim 17 further comprising a second pair of collinear contact image sensors, wherein the second pair of collinear contact image sensors are positioned to intersect a center of the interior.