Substrate Stage Thrust Continuity for Overlay-Accurate Exposure
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Solution Overview
Problem
Existing exposing apparatuses face control deviations in substrate stage positioning due to instantaneous actuator switching, leading to deteriorated overlay accuracy while attempting to improve throughput by varying substrate stage acceleration.
Innovation Solution
The apparatus employs a driving profile with a differentiable acceleration function and continuous thrust application by multiple electromagnet actuators, ensuring that actuators do not switch instantaneously, maintaining continuous thrust application during exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate stage is moved by switching from the first actuator to the second actuator when acceleration becomes zero, then the throughput is improved by reducing exposure time, but the control deviation occurs and overlay accuracy deteriorates
Solution Approach 1:
The patent applies the continuity principle by making both actuators operate simultaneously during the transition period. Instead of switching from one actuator to another, both actuators generate thrust at the same time, ensuring continuous and smooth acceleration control without interruption or deviation, thereby maintaining both high throughput and overlay accuracy
2Loss of time
If the acceleration of the substrate stage is varied from positive to negative by switching actuators, then the exposure time is reduced to improve throughput, but the control system becomes complex due to coordination requirements
Solution Approach 1:
The patent merges the operation of both actuators by having them generate thrust simultaneously during the transition period. This combining approach simplifies the control logic compared to complex switching mechanisms, as both actuators work together in a coordinated manner to achieve smooth acceleration variation while reducing exposure time
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach suppresses control deviations and maintains high overlay accuracy, allowing for efficient exposure of substrate regions without hardware limitations.
Implementation Method 1
a driving unit configured to drive the substrate stage with a plurality of actuators each configured to apply a thrust to the substrate stage
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The exposing apparatus according to the present invention for exposing a substrate so as to transfer a pattern formed on an original to the substrate by using exposure light from a light source, includes a substrate stage on which the substrate is mounted, a driving unit configured to drive the substrate stage with a plurality of actuators each configured to apply a thrust to the substrate stage in respective orientations different from each other, and a controller configured to control the driving unit to cause the substrate stage to move in the scanning direction when exposing each of a plurality of shot regions on the substrate, and to cause each of the plurality of actuators to apply the thrust to the substrate stage in at least a part of time duration of each movement in the scanning direction.