Waveplate Compensator Structure to Eliminate Bonding Strain
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Solution Overview
Problem
Previous waveplate compensators in metrology tools suffer from poor yield, reduced measurement accuracy, and reduced tool-to-tool matching due to strain-induced optical distortions at quartz-to-quartz optical contact bonds.
Innovation Solution
The waveplate compensator design incorporates birefringent material layers separated by spacer layers using optical contact bonding to eliminate strain at the interface, utilizing materials like fused silica or quartz, and avoiding direct contact between birefringent layers to reduce optical distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If quartz-to-quartz optical contact bonds are used in waveplate compensators, then manufacturing is simplified, but strain-induced optical distortions occur reducing measurement accuracy
Solution Approach 1:
A spacer layer made of fused silica is introduced as an intermediary between the quartz waveplate layers. This spacer layer eliminates direct quartz-to-quartz optical contact bonds, preventing strain-induced optical distortions while maintaining manufacturing feasibility through optical contact bonding of the spacer to the quartz layers.
2Device complexity
If direct optical contact bonding is used between birefringent layers, then device complexity is reduced, but tool-to-tool matching deteriorates
Solution Approach 1:
The spacer layer serves as a mediator that standardizes the interface between birefringent layers. By using identical spacer layers in all waveplate compensators, tool-to-tool matching is improved while the overall structure remains relatively simple through the use of optical contact bonding.
Solution Approach 2:
The optical contact bonding process is used to join the spacer layer to the quartz layers, creating a reliable connection that ensures consistent optical properties across different tools while maintaining manufacturing feasibility.
3Measurement precision
If thicker birefringent material layers are used, then optical compensation is improved, but strain effects are amplified reducing yield
Solution Approach 1:
The spacer layer acts as a strain isolation intermediary that protects the birefringent material layers from strain effects. This allows the use of thicker birefringent layers for improved optical compensation while maintaining high manufacturing yield by preventing strain-induced defects.
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 design improves tool yield and measurement accuracy by minimizing strain-induced distortions, enhancing tool matching and accuracy in metrology tools.
Implementation Method 1
The birefringent material layers and the spacer layers are disposed in contact with each other using optical contact bonding
Implementation Method 2
Each of the birefringent material layers has a non-zero thickness less than or equal to 35 μm
Data Source
AI summary
A waveplate compensator includes birefringent material layers and spacer layers. Each of the birefringent material layers has a thickness less than or equal to 35 μm. Each adjacent pair of the birefringent material layers in a stack is separated by one of the spacer layers. The birefringent material layers and the spacer layers are disposed in contact with each other using optical contact bonding.