Orthogonal Reflecting Member for Interferometer Height Measurement
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Solution Overview
Problem
Conventional interferometer systems for height position measurement in semiconductor fabrication face challenges such as increased apparatus size due to the need for a reflecting plate above the stage and susceptibility to measurement errors from changes in the stage's attitude, leading to detection failures and positional deviations.
Innovation Solution
A reflecting member with orthogonal reflecting surfaces is used, allowing for positional measurement without increasing the apparatus size and reducing measurement errors by shifting the optical axis and shortening the optical path length, thereby minimizing angular deviations and positional deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reflecting plate is provided above a movable stage for height position measurement, then the position of the stage can be measured, but the location for installing downflow equipment cannot be secured and the apparatus size increases
Solution Approach 1:
The reflecting member is configured with reflecting surfaces that extend in multiple directions (first direction component and second direction component substantially orthogonal to the first), allowing the interferometer to measure height position without requiring the reflecting plate to be positioned above the stage in the vertical dimension. This dimensional reconfiguration enables downflow equipment to be installed while maintaining measurement capability
Solution Approach 2:
The reflecting member employs an asymmetric configuration with multiple reflecting surfaces extending in different directions rather than a simple planar mirror. This asymmetric design allows the beam to be reflected along multiple paths, enabling height measurement without increasing the vertical space requirement and allowing equipment to be positioned below the stage
2Measurement precision
If a conventional interferometer system with a long optical path is used, then height position can be measured, but changes in the attitude of the stage result in large positional deviations and detection failures
Solution Approach 1:
The reflecting member extends reflecting surfaces in multiple directions (first direction and second direction substantially orthogonal to the first), creating a three-dimensional reflection geometry. This multi-dimensional configuration ensures that at least one reflecting surface maintains a valid reflection path even when the stage attitude changes, preventing detection failures that occur with conventional single-path systems
Solution Approach 2:
The invention changes the geometric parameters of the reflection system by providing multiple reflecting surfaces at different orientations. When the stage attitude changes, the optical path lengths of beams reflected by different surfaces change differently, allowing the system to maintain measurement capability through parameter variation rather than failure
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
Enables precise positional measurement of a movable stage without increasing the apparatus size and reduces the incidence of detection failures and measurement errors due to changes in the stage's attitude, improving measurement accuracy and reliability.
Implementation Method 1
a first reflecting surface that extends in a second direction, which includes a first direction component; a second reflecting surface that extends in a third direction, which includes the first direction component, and is substantially symmetric to the first reflecting surface; and a third reflecting surface that extends in a fourth direction substantially orthogonal to the first direction
Data Source
AI summary
A reflecting member has: a first reflecting surface, which extends in a second direction that includes a first direction component; a second reflecting surface, which extends in a third direction that includes the first direction component, that is substantially symmetric to the first reflecting surface; and a third reflecting surface, which extends in a fourth direction, that is substantially orthogonal to the first direction.