Miniature Optically Transparent Windows for Horizontal Light Transmission
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Solution Overview
Problem
Semiconductor fabrication techniques are limited in forming miniature optically transparent windows that allow light to pass horizontally, which is essential for compact, high-performance devices like chip-scale atomic clocks and other optical devices.
Innovation Solution
A method involving a substrate with recesses filled with optically transparent material, supported by layers that allow light to pass through in a horizontal direction, using techniques like Deep-Reactive-Ion-Etching and photo-patterning to form miniature optically transparent windows on a Silicon-On-Insulator wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If semiconductor fabrication techniques are used to form miniature windows, then manufacturing precision and integration are improved, but the ability to form horizontally transparent windows is limited
Solution Approach 1:
The patent transitions from conventional planar window formation to three-dimensional vertical window structures by forming recesses that extend through the substrate thickness. This dimensional change enables horizontal light transmission capability while maintaining semiconductor fabrication precision through controlled etching processes.
Solution Approach 2:
The window formation process is segmented into distinct steps: forming recesses in the first layer, filling with transparent material, and removing portions of the first layer. This segmentation allows precise control over window geometry and transparency characteristics using standard semiconductor fabrication techniques.
2Adaptability or versatility
If bonding transparent structures onto MEMS wafer surfaces is used, then horizontal light transmission is achieved, but fabrication complexity and reliability are reduced
Solution Approach 1:
The patent merges the window formation process directly into the MEMS wafer fabrication sequence by forming recesses and filling them with transparent material as integral steps. This eliminates the need for separate bonding operations and reduces fabrication complexity while maintaining horizontal light transmission capability.
Solution Approach 2:
The transparent material is placed in recesses before final wafer processing steps, allowing the window structures to be formed preliminarily during fabrication rather than added as post-processing elements. This preliminary action simplifies the overall fabrication process and improves reliability.
3Strength
If thicker silicon substrate is used in SOI wafer, then mechanical strength is improved, but window thickness and light transmission are reduced
Solution Approach 1:
The substrate is segmented into functional layers with the first layer containing the recesses and the second layer providing support. This segmentation allows the thicker first layer to maintain mechanical strength while the recess structure enables light transmission through the transparent material filling, resolving the contradiction between substrate thickness and optical performance.
Data Source
AI summary
Miniature optically transparent windows are disclosed that extend vertically from a plane, which may be used to transmit light traveling in a direction substantially parallel with the plane. In one illustrative embodiment, a method for forming such miniature optically transparent windows includes: providing a substrate having a first surface and an opposing second surface, the substrate having a first layer and an adjacent second layer; forming a recess in the first layer of the substrate, the recess extending to the second layer; providing an optically transparent material in the recess to form an optically transparent feature; and removing at least a portion of the first layer that extends adjacent the optically transparent feature so that light can pass through the optically transparent feature in a direction that is substantially parallel to the first surface of the substrate.