Semiconductor workpiece temperature measurement system
An improved system and method of measuring the temperature of a workpiece being processed is disclosed. The temperature measurement system determines a temperature of a workpiece by measuring the amount of expansion in the workpiece due to thermal expansion. The amount of expansion may be measured using a number of different techniques. In certain embodiments, a light source and a light sensor are disposed on opposite sides of the workpiece. The total intensity of the signal received by the light sensor may be indicative of the dimension of the workpiece. In another embodiment, an optical micrometer may be used. In another embodiment, a light sensor may be used in conjunction with a separate device that measures the position of the workpiece.
1. An apparatus for measuring a temperature of a workpiece, comprising:
a first light emitter transmitting a first light beam;
a first light sensor to receive the first light beam;
a second light emitter transmitting a second light beam;
a second light sensor to receive the second light beam;
a scanning stage adapted to hold a workpiece, wherein the scanning stage translates the workpiece so that the workpiece interrupts the first light beam at a first point, wherein each point at which the first light sensor or the second light sensor detects a change in received light is defined as a workpiece edge detection point;
a position sensor to measure movement of the scanning stage;
and
a controller in communication with the first light sensor, the second light sensor and the position sensor, and wherein the controller records three measurements from the position sensor at three workpiece edge detection points, and based on the three measurements from the position sensor, determines a temperature of the workpiece.
2. The apparatus of claim 1 , wherein the second light beam is interrupted by the workpiece at a second point, and the scanning stage continues translating the workpiece until the first light beam is no longer interrupted by the workpiece at a third point, and the second light beam is no longer interrupted by the workpiece at a fourth point, and wherein the controller uses three points selected from the group consisting of the first point, the second point, the third point and the fourth point as the three workpiece edge detection points to determine the temperature of the workpiece.
3. The apparatus of claim 1 , comprising a third light emitter and a third light sensor, wherein the controller records a measurement at a second point at which a third light beam received by the third light sensor is interrupted, and uses the second point as one of the three workpiece edge detection points to determine the temperature of the workpiece.
4. The apparatus of claim 1 , further comprising an ion source, where the workpiece is implanted with ions from the ion source while the scanning stage translates the workpiece.
5. The apparatus of claim 1 , wherein the workpiece is disposed on a platen and heating elements are embedded in the platen.
6. The apparatus of claim 5 , wherein an amount of heat emitted by the heating elements is based on the temperature of the workpiece.
7. An apparatus for measuring a temperature of a workpiece, comprising:
a first light emitter transmitting a first light beam;
a first light sensor to receive the first light beam;
a second light emitter transmitting a second light beam;
a second light sensor to receive the second light beam;
a third light emitter transmitting a third light beam;
a third light sensor to receive the third light beam;
a scanning stage adapted to hold a workpiece, wherein the scanning stage translates the workpiece, and wherein each point at which the first light sensor, the second light sensor or the third light sensor detects a change in received light is defined as a workpiece edge detection point;
a position sensor to measure movement of the scanning stage;
and
a controller in communication with the first light sensor, the second light sensor, the third light sensor and the position sensor, and wherein the controller records three measurements from the position sensor at three workpiece edge detection points, and based on the three measurements from the position sensor, determines a temperature of the workpiece.
8. The apparatus of claim 7 , wherein the workpiece interrupts the first light beam at a first point, interrupts the second light beam at a second point, and interrupts the third light beam at a third point, and the controller records the three measurements from the position sensor at the first point, the second point and the third point.
9. The apparatus of claim 7 , further comprising an ion source, where the workpiece is implanted with ions from the ion source while the scanning stage translates the workpiece.
10. The apparatus of claim 7 , wherein the workpiece is disposed on a platen and wherein heating elements are embedded in the platen.
11. The apparatus of claim 10 , wherein an amount of heat emitted by the heating elements is based on the temperature of the workpiece.