Single-Crystal Silicon Molds for Precise Angled Optical Glass Covers
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Solution Overview
Problem
Existing methods for manufacturing angled optical windows in optical glass covers for MEMS devices are complex and costly, and controlling the inclination of these windows is difficult, leading to issues like bright spots or lines in the image area.
Innovation Solution
A method using a single-crystal silicon mold is employed to shape borosilicate glass with angled optical windows, involving patterning, wet-etching, molding, and anodic bonding to create a silicon device wafer, followed by etching and dicing to separate devices with angled optical windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If glass sheet is deformed to create angled optical windows with reinforcing elements, then bright spots are prevented from coinciding within the intended image area, but the manufacturing process becomes difficult and costly, and controlling the inclination is difficult
Solution Approach 1:
Instead of deforming glass sheet to create angled windows, the patent inverts the approach by using a silicon mold with pre-formed angled recesses to shape the glass. The glass is molded into the angled recesses rather than being deformed from a flat state, simplifying the manufacturing process while maintaining the bright spot prevention function.
Solution Approach 2:
The patent uses a silicon mold that copies the desired angled window geometry into the glass. The mold contains recesses with the exact angled shapes needed, and the glass is molded to match these recesses, providing precise control over inclination without complex manufacturing steps.
2Object-affected harmful factors
If glass sheet is deformed to create angled optical windows, then bright spots are prevented, but the reinforcing elements add cost and control difficulty
Solution Approach 1:
The patent extracts the angle-defining function from complex reinforcing elements and integrates it directly into the mold structure. The silicon mold contains recesses with the precise angled geometry, eliminating the need for separate reinforcing elements while maintaining the bright spot prevention capability.
Solution Approach 2:
The silicon mold serves multiple functions: it defines the angled geometry of the optical windows, provides structural support during molding, and enables precise control of inclination. This multi-functional approach replaces the need for separate reinforcing elements, simplifying the overall device structure.
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
The method is straightforward and cost-effective, producing angled optical windows with well-defined tilting angles, reducing bright spots or lines in the image area, and ensuring high-quality glass covers for MEMS devices.
Implementation Method 1
wet-etching the plurality of unmasked areas to reveal respective a plurality of Si(111) surfaces of the off-axis cut silicon wafer, to form a silicon mold comprising a plurality of angled recesses
Implementation Method 2
heating up the sheet of borosilicate glass, and applying an inert pressure to cause the heated sheet of borosilicate glass to adapt to the shape of the silicon mold
Implementation Method 3
molding borosilicate glass using the silicon mold to form a plurality of angled glass portions
Implementation Method 4
cooling the molded borosilicate glass
Implementation Method 5
anodically bonding the polished borosilicate glass to a silicon device wafer
Implementation Method 6
removing the silicon mold by etching to release a wafer stack with borosilicate glass and the silicon device wafer
Data Source
Figure 1~2
Figure 3A~3C
Figure 3D~3F
AI summary
The disclosure relates to methods of manufacturing a plurality of devices having an optical glass cover comprising an angled optical window. An off-axis cut silicon wafer is used as a mold for molding borosilicate glass to form a plurality of angled glass portions. The polished borosilicate glass is anodically bonded to a silicon device wafer comprising a plurality of structures and/or circuitry for the plurality of devices. After removing the silicon mold by etching, the silicon wafer stack is diced to separate the plurality of devices, each having the optical glass cover comprising a respective angled optical window determined by one of the angled recesses of the silicon mold.