Vacuum Stage Segmentation for Positioning Accuracy
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Solution Overview
Problem
Conventional exposure apparatuses using charged particle beams or EUV light face challenges in maintaining high accuracy due to pressure differentials between vacuum and atmospheric pressures, leading to deformation of stage apparatus components and vacuum chambers, which affects positioning accuracy.
Innovation Solution
A stage apparatus design with a first space for the object, a movable member that covers the opening, and a second space for the movable member, allowing independent gas pressure control to minimize pressure differentials and maintain constant gas pressures, reducing deformation and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If part of the stage apparatus is exposed to atmospheric pressure inside the vacuum chamber, then the stage apparatus can be driven with good accuracy, but the pressure differential between atmospheric pressure and vacuum will deform the constituent members of the stage apparatus
Solution Approach 1:
The vacuum chamber is divided into multiple independent vacuum spaces (first vacuum space and second vacuum space) separated by partition walls. The stage apparatus is segmented accordingly, with different parts located in different vacuum spaces. This segmentation allows independent pressure control in each space, reducing the pressure differential acting on individual components and minimizing deformation while maintaining positioning accuracy.
Solution Approach 2:
A movable member is introduced as an intermediary element that covers the opening between the first and second vacuum spaces. This movable member can be positioned to seal the opening, preventing pressure equalization between spaces. The movable member acts as a mediator that maintains the pressure differential necessary for accurate stage positioning while protecting components from excessive pressure differential.
2Reliability
If the vacuum chamber is large and maintains vacuum atmosphere, then the exposure beam can pass through without absorption, but the internal/external pressure differential constitutes a huge force that will deform the vacuum chamber
Solution Approach 1:
The large vacuum chamber is divided into multiple smaller vacuum spaces (first vacuum space for the object, second vacuum space for the movable member). Each smaller space experiences reduced total force from pressure differential compared to a single large space, while collectively maintaining the vacuum environment needed for exposure beam transmission. The partition walls distribute the structural load.
3Measurement precision
If atmospheric pressure fluctuates, then the amount of deformation of the vacuum chamber and stage apparatus components will vary, affecting positioning accuracy
Solution Approach 1:
By dividing the vacuum chamber into separate vacuum spaces with partition walls, the patent isolates different components from each other. When atmospheric pressure fluctuates, each segmented space maintains its own pressure differential independently, preventing coupled deformation effects. This segmentation stabilizes the relative positions of components across different pressure zones.
Solution Approach 2:
The movable member serving as the opening cover acts as a mediator that isolates the first and second vacuum spaces. This intermediary element ensures that pressure fluctuations in one space do not directly transmit to the other space, maintaining stable pressure differentials and consistent component dimensions despite external atmospheric pressure changes.
Data Source
AI summary
The present invention provides a stage apparatus wherein an object is disposed in an atmosphere with a gas pressure lower than atmospheric pressure, and the object can be driven with high accuracy. The stage apparatus that drives a reticle comprises: a vacuum chamber, which forms a space and has an opening; an integrated coarse and fine motion table, which has an electrostatic chuck that holds the object, that, when driven, moves the electrostatic chuck inside the space; a counter mass, which is disposed so that it covers the opening, that is capable of moving because of the reaction force produced when the integrated coarse and fine motion table is driven; and a vacuum cover, which forms a space that houses the counter mass; wherein the space and the space are set to prescribed gas pressures.