System and method of verifying workpiece alignment
A workpiece processing system and method are disclosed for determining an alignment of a workpiece upon a workpiece support using a retractable sensor. A sensor moves in/out relative to an edge of the workpiece support to obtain positional data while the workpiece support is rotated. Based on the positional data, the alignment of the workpiece and workpiece support may be determined. After determining the alignment, the sensor may be retracted behind the workpiece support, such that the sensor is shielded by the workpiece support from an ion beam during ion implantation. Using a helical motion, an angle between the sensor and a support surface of the workpiece support may be maintained approximately constant during the measurement.
1 . A workpiece characterization system, comprising:
a process chamber;
a process medium source configured to generate a process medium along a process medium path;
a workpiece support having a support surface defining a support plane, wherein the workpiece support is configured to selectively support a workpiece on the support surface and to selectively expose the workpiece to the process medium along the process medium path within the process chamber;
a sensor;
a coupling apparatus operably coupled to the sensor, wherein the coupling apparatus comprises a guide member and a sensor arm; and
an actuator arranged downstream of the support plane when viewed along the process medium path, wherein the actuator is operably coupled to the coupling apparatus and configured to selectively translate the sensor along a curvilinear sensor path between a first position and a second position via the coupling apparatus, wherein the sensor is positioned downstream of the support plane in the first position when viewed along the process medium path, and wherein the sensor is positioned at least partially upstream of the support plane in the second position when viewed along the process medium path, wherein the sensor is configured to detect a peripheral edge of the workpiece in the second position, wherein the actuator is configured to selectively control a motion of the sensor arm with respect to the guide member, thereby controlling a motion of the sensor along the curvilinear sensor path, wherein the sensor arm has a first end portion and a second end portion, wherein the first end portion is operably coupled to the actuator and the second end portion is operably coupled to the sensor, and wherein the actuator is fixed with respect to the guide member and comprises a linear actuator configured to linearly translate a drive shaft along a drive axis, wherein the first end portion of the sensor arm is coupled to a distal end of the drive shaft, wherein the guide member comprises a helical groove, and wherein the drive shaft comprises a follower, wherein the follower slidingly engages the helical groove to define the curvilinear sensor path.
2 . The workpiece characterization system of claim 1 , wherein the actuator, the coupling apparatus, and the sensor are generally shielded by one or more of the workpiece and the workpiece support when the sensor is in the first position.
3 . The workpiece characterization system of claim 1 , wherein the sensor comprises one or more of a photoelectric sensor, a light curtain, and a laser.
4 . The workpiece characterization system of claim 1 , further comprising a controller configured to control the actuator and the sensor, wherein the actuator comprises an encoder configured to provide positional data associated with the translation of the sensor along the curvilinear sensor path to the controller, and wherein the controller is configured to determine a relative position of the workpiece with respect to the workpiece support based on the detection of the peripheral edge of the workpiece by the sensor and the positional data from the encoder.
5 . The workpiece characterization system of claim 4 , wherein the workpiece support further comprises a robot configured to selectively rotate the workpiece support about a support axis, and wherein the controller is further configured to control the robot and to determine the relative position of the workpiece with respect to the workpiece support concurrent with the selective rotation of the workpiece support.
6 . The workpiece characterization system of claim 5 , wherein the peripheral edge of the workpiece comprises an alignment feature defined therein, and wherein the controller is further configured to determine the relative position of the workpiece with respect to the workpiece support further based on a detection of the alignment feature by the sensor.
7 . The workpiece characterization system of claim 5 , wherein the controller is configured to determine the relative position of the workpiece with respect to the workpiece support at a plurality of rotational positions of the workpiece support about the support axis.
8 . The workpiece characterization system of claim 1 , wherein the actuator is further configured to selectively translate the sensor along the curvilinear sensor path to an intermediate position between the first position and the second position.
9 . The workpiece characterization system of claim 1 , wherein the workpiece support comprises an electrostatic chuck.