Movable Light Shielding Units for Exposure Apparatus Telecentricity
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Solution Overview
Problem
The existing exposure apparatuses face challenges in maintaining the centroid light beam alignment and telecentricity during exposure, leading to decreased overlay accuracy due to shifts in the centroid light beam of the light intensity distribution on the surface to be illuminated.
Innovation Solution
The exposure apparatus incorporates a first and second light shielding unit with movable light shielding members, positioned away from the conjugate plane, to adjust the relative distances and apertures, ensuring the centroid light beam remains parallel to the optical axis, thereby maintaining telecentricity and preventing shifts in the light intensity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light shielding units are arranged at defocused positions to make the centroid light beam parallel to the optical axis, then the telecentric degree is improved, but the overlay accuracy decreases when the centroid light beam shifts due to focus deviation
Solution Approach 1:
The patent makes the light shielding units movable rather than fixed, allowing dynamic adjustment of their positions. The adjustment unit can change the distance between the light shielding units and the conjugate plane, enabling the system to adapt to different focus conditions and maintain both telecentricity and overlay accuracy under varying operational conditions.
Solution Approach 2:
The patent changes the positional parameter of the light shielding units by allowing movement along the optical axis. By adjusting the distance from the conjugate plane, the system can optimize the balance between telecentric degree and overlay accuracy, resolving the contradiction between these two precision requirements.
2Device complexity
If the relative distance between light shielding members is fixed, then the device complexity is reduced, but the ability to suppress centroid light beam shifts under varying focus conditions is limited
Solution Approach 1:
The light shielding units are designed with movable components that can adjust their relative positions dynamically. This dynamic capability allows the system to maintain centroid light beam stability under varying focus conditions without requiring an overly complex fixed structure, achieving reliability through adaptability rather than rigid complexity.
3Volume of moving object
If the light shielding units are positioned closer to the conjugate plane, then the device size is reduced, but the telecentric degree decreases
Solution Approach 1:
Rather than using a large fixed distance, the patent employs a movable light shielding unit that can dynamically position itself at the optimal distance from the conjugate plane. This allows the system to maintain high telecentric degree when needed while keeping the overall device compact, as the light shielding unit occupies minimal space when retracted but can extend to optimal positions during operation.
Data Source
AI summary
There is provided an exposure apparatus including a first light shielding unit including a first light shielding member and a second light shielding member, which include end potions facing each other in a scanning direction and in which a relative distance therebetween in the scanning direction can be changed, and arranged at a position away from a conjugate plane of a surface to be illuminated to a side of a light source, and a second light shielding unit including a third light shielding member and a fourth light shielding member, which include end portions facing each other in the scanning direction and in which a relative distance therebetween in the scanning direction can be changed, and arranged at a position away from the conjugate plane to a side of the surface.