Method for controlling and monitoring light source intensity
AssigneeAdvanced Micro Devices, Inc.
InventorsAnthony John Toprac, Richard David Edwards, Curtis Warren Doss
Life of this patent
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Abstract
In one illustrative embodiment, a method is provided that comprises energizing a light source to provide light having a preselected intensity. A first photosensor, which is capable of delivering a first signal indicative of the intensity of the light source, is exposed to the light source. A second photosensor, which is also capable of delivering a second signal indicative of the intensity of the light source, is also exposed to the light source. Thereafter, the first and second signals are compared, and an error signal is delivered in response to detecting a significant difference between the first and second signals.
Claims18
A method, comprising:
- energizing a light source to provide light having a preselected intensity;
- exposing a first photosensor to the light source, wherein the first photosensor is capable of delivering a first signal indicative of the intensity of the light source;
- exposing a second photosensor to the light source, wherein the second photosensor is capable of delivering a second signal indicative of the intensity of the light source;
- comparing the first and second signals;
- and
- delivering an error signal in response to detecting a difference of a preselected magnitude between the first and second signals.
A method for controlling a stepper, comprising:
- providing a wafer having a layer of photoresist disposed thereon;
- energizing a light source to deliver light having a preselected intensity onto the layer of photoresist for a preselected duration of time;
- exposing a first photosensor to the light source, wherein the first photosensor is capable of delivering a first signal indicative of the intensity of the light source;
- exposing a second photosensor to the light source, wherein the second photosensor is capable of detecting the intensity of the light source;
- comparing the first and second signals to determine a difference there between;
- and
- determining a duration of time for exposing a subsequent wafer to said light source based upon of the difference between the first and second signals.
A method, comprising:
- energizing a first light source to provide light having a first preselected intensity;
- exposing a photosensor to the first light source, wherein the photosensor is capable of delivering a first signal indicative of the intensity of the first light source;
- controlling a duration that the first light source is energized based on the first signal;
- periodically energizing a second light source to provide light having a second preselected intensity;
- exposing the photosensor to the second light source, wherein the photosensor is capable of delivering a second signal indicative of the intensity of the second light source;
- comparing the second signal with a preselected setpoint;
- and
- delivering an error signal in response to detecting a difference of a preselected magnitude between the second signal and the preselected setpoint.
Dependencies are inferred from the claim text.