Wafer prescence detector with end effectors having optical couplers and fibers
View Patent ↗The presence of a workpiece on an end effector of a vacuum robotic handler is detecting using any of a number of non-contact techniques in which some or all of the detection hardware is positioned outside a vacuum chamber that encloses the vacuum robotic handler. Various deployments include laser beam breaking, analysis of radar reflection signals, or analysis of radio frequency identification tag signatures. By providing non-physical couplings between hardware inside and outside of a vacuum environment, integrity of the vacuum is improved. These non-contact techniques are further adapted as described herein to multi-wafer and multi-end effector environments so that independent detection of multiple wafers (e.g., for each end effector) can be performed.
1. A system comprising:
a first and second laser;
a first and second detector;
a first end effector of a vacuum robotic handler, the vacuum robotic handler positioned within a vacuum chamber and the first end effector having a first pair of optical couplers, one of the optical couplers being positioned to receive light from the first laser across a vacuum gap and the one of the optical couplers being configured to couple the light from the first laser to a first source fiber that directs the light across a first workpiece support plane of the first end effector, and another one of the optical couplers being positioned to transmit light to the first detector across the vacuum gap and the another one of the optical couplers being configured to couple light from a first target fiber, that has a receiving end positioned on an opposing side of the first workpiece support plane from the first source fiber and oriented to receive light therefrom, to the first detector so that placement of a workpiece on the first end effector in the first workpiece support plane is detected; and
a second end effector of the vacuum robotic handler, the second end effector having a second pair of optical couplers, one of the optical couplers being positioned to receive light from the second laser across the vacuum gap and the one of the optical couplers being configured to couple the light from the second laser to a second source fiber that directs the light across a second workpiece support plane of the second end effector, and another one of the optical couplers being positioned to transmit light to the second detector across the vacuum gap and the another one of the optical couplers being configured to couple light from a second target fiber, that has a receiving end positioned on an opposing side of the second workpiece support plane from the second source fiber and oriented to receive light therefrom, to the second detector so that placement of a workpiece on the second end effector in the second workpiece support plane is detected.
2. The system of claim 1 wherein the second end effector further includes a transmissive region positioned to pass light between the first pair of optical couplers and the first laser and the first detector.
3. The system of claim 2 wherein the first end effector and the second end effector are independently movably, the transmissive region passing light between the first pair of optical couplers and the first laser and the first detector only when the first end effector and the second end effector are in a specific relative orientation.
4. The system of claim 2 wherein the transmissive region of the second end effector is a hole through the second end effector.
5. The system of claim 1 wherein the first laser is positioned outside the vacuum chamber, the vacuum chamber including a light transmissive wall region that passes light between an interior of the vacuum chamber and the first laser.
6. The system of claim 5 wherein the first laser is mounted to the transmissive wall region.
7. The system of claim 5 wherein the first laser is positioned to couple to the one of the first pair of optical couplers only when the first end effector is in a predetermined position.
8. The system of claim 1 wherein the first detector is positioned outside the vacuum chamber, the vacuum chamber including a light transmissive wall region that passes light between an interior of the vacuum chamber and the first detector.
9. The system of claim 8 wherein the first detector is mounted to the transmissive wall region.
10. The system of claim 8 wherein the second detector is positioned outside the vacuum chamber.
11. The system of claim 10 wherein the first laser is positioned outside the vacuum chamber.
12. The system of claim 11 wherein the second laser is positioned outside the vacuum chamber.
13. The system of claim 1 further comprising a processing system that measures a light detection signal from at least one of the first detector and the second detector and determines whether a workpiece is present within the workpiece support plane based upon the light detection signal.
14. The system of claim 1 further comprising a motion control system for the vacuum robotic handler, the motion control system configured to place the vacuum robotic handler in a home position in which wafer presence detection can be performed.
15. The system of claim 1 wherein the first laser and the second laser are excited concurrently.
16. The system of claim 1 wherein the vacuum robotic handler handles one or more of a reticle and a semiconductor wafer.
17. A system comprising:
a first and second laser;
a first and second detector;
a first end effector of a vacuum robotic handler, the vacuum robotic handler positioned within a vacuum chamber and the first end effector having a first pair of optical couplers, one of the optical couplers being positioned to receive light from the first laser across a vacuum gap and the one of the optical couplers being configured to couple the light from the first laser to a first source fiber that directs the light across a first workpiece support plane of the first end effector, and another one of the optical couplers being positioned to transmit light to the first detector across the vacuum gap and the another one of the optical couplers being configured to couple light from a first target fiber, that has a receiving end positioned on an opposing side of the first workpiece support plane from the first source fiber and oriented to receive light therefrom, to the first detector; and
a second end effector of the vacuum robotic handler, the second end effector having a second pair of optical couplers, one of the optical couplers being positioned to receive light from the second laser across the vacuum gap and the one of the optical couplers being configured to couple the light from the second laser to a second source fiber that directs the light across a second workpiece support plane of the second end effector, and another one of the optical couplers being positioned to transmit light to the second detector across the vacuum gap and the another one of the optical couplers being configured to couple light from a second target fiber, that has a receiving end positioned on an opposing side of the second workpiece support plane from the second source fiber and oriented to receive light therefrom, to the second detector;
wherein the first laser is positioned outside the vacuum chamber, the vacuum chamber including a light transmissive wall region that passes light between an interior of the vacuum chamber and the first laser.