Fabry-Perot Filter Wafer Structure for High-Yield Dicing
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Solution Overview
Problem
Manufacturing Fabry-Perot interference filters is challenging due to low efficiency and yield, primarily because of the difficulty in handling and cutting the delicate mirror structures without damaging them.
Innovation Solution
A wafer design with a configuration that includes multiple Fabry-Perot interference filter portions surrounded by dummy filter portions, featuring an intermediate layer between the mirrors to enhance strength and a continuous groove system to reduce stress and warpage, facilitating efficient cutting and high yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a Fabry-Perot interference filter is manufactured as a fine structure, then the filter performance is improved, but manufacturing efficiency and yield deteriorate
Solution Approach 1:
Multiple Fabry-Perot interference filters are merged into a single wafer structure, allowing simultaneous manufacturing of multiple filters. The wafer includes a substrate layer with multiple filter portions arranged thereon, enabling batch production while maintaining the fine structure precision of each individual filter.
Solution Approach 2:
The wafer structure serves multiple functions: it acts as a substrate for multiple filters, provides mechanical support through the substrate layer, and enables batch processing. The intermediate layer serves both as a structural element and as a support for the movable mirror portions across all filter units.
2Manufacturing precision
If the intermediate layer is removed to form a gap for the Fabry-Perot interference filter, then the filter functionality is improved, but the strength of the wafer deteriorates
Solution Approach 1:
The intermediate layer is selectively removed only in specific regions where Fabry-Perot interference filters are to be formed, while retaining the layer in other regions to maintain wafer strength. The dummy filter portions include intermediate layers that provide mechanical support, creating local variations in structure quality.
Solution Approach 2:
The wafer is segmented into effective areas with gaps (for functional filters) and dummy areas with intermediate layers (for structural support). This segmentation allows different regions to serve different purposes: functional regions with removed intermediate layers for filter operation, and support regions with retained intermediate layers for mechanical strength.
3Ease of operation
If the dummy area is gripped by a gripper tool for handling, then the ease of operation is improved, but the second mirror portion may be damaged and adhere to the filter portion
Solution Approach 1:
The intermediate layer in dummy filter portions acts as an intermediary that prevents direct contact between the gripper tool and the second mirror portion. When the gripper grips the dummy area, the intermediate layer absorbs the contact force, preventing damage to the second mirror portion and avoiding adhesion to the Fabry-Perot interference filter portion.
4Productivity
If multiple filters are cut out from the wafer, then the productivity is improved, but the yield deteriorates due to damage during cutting
Solution Approach 1:
Grooves are formed in advance in the substrate layer at positions corresponding to the boundaries between filter portions before cutting. These pre-formed grooves guide the cutting process and reduce stress concentration, preventing crack propagation that could damage multiple filters during the cutting operation.
Data Source
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AI summary
A wafer includes a substrate layer, a first mirror layer having a plurality of two-dimensionally arranged first mirror portions, and a second mirror layer having a plurality of two-dimensionally arranged second mirror portions. A plurality of Fabry-Perot interference filter portions are formed in an effective area, in each of the plurality of Fabry-Perot interference filter portions a gap is formed between the first mirror portion and the second mirror portion. A plurality of dummy filter portions are formed in a dummy area disposed along an outer edge of the substrate layer and surrounding the effective area, in each of the plurality of dummy filter portions an intermediate layer is provided between the first mirror portion and the second mirror portion. At least the second mirror portion is surrounded by the first groove in each of the plurality of Fabry-Perot interference filter portions and the plurality of dummy filter portions.