Self-Limiting Alignment Marks for Substrate Packaging
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Solution Overview
Problem
Existing packaging techniques for optical devices, such as MEMS and spatial light modulators, face challenges with low yields and difficulty in scaling up due to complex and costly manufacturing processes, particularly in aligning and bonding substrates for composite substrate packages.
Innovation Solution
A method and structure for aligning and packaging optical devices involve forming alignment marks on handle and spacer substrates, using self-limiting alignment marks and standoff regions to facilitate precise alignment and bonding, enabling the formation of composite substrate structures with improved accuracy and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional packaging techniques are used for MEMS and spatial light modulators, then device functionality is achieved, but manufacturing yields are low and scaling is difficult
Solution Approach 1:
The packaging process is divided into separate alignment and bonding stages. Alignment marks are formed on both substrates before bonding, allowing precise positioning to be achieved independently of the bonding process itself. This segmentation enables systematic error correction and improves overall yield.
Solution Approach 2:
Alignment marks are formed on both substrates in advance before the bonding operation. This preliminary alignment preparation allows the substrates to be precisely positioned relative to each other before irreversible bonding occurs, preventing misalignment defects and improving manufacturing yield.
2Manufacturing precision
If precise alignment is achieved through conventional methods, then substrate positioning is adequate, but manufacturing cost and complexity increase
Solution Approach 1:
The alignment marks on both substrates work together in a self-aligning system. The marks are designed to be mutually referenceable, allowing the substrates to find their correct relative positioning through the alignment marks themselves without requiring complex external alignment equipment or procedures.
Solution Approach 2:
Alignment marks are formed on both substrates as complementary copies of each other. These matching marks serve as mutual references during alignment, enabling precise positioning through simple optical or mechanical recognition of the mark patterns without requiring complex alignment machinery.
3Reliability
If complex MEMS packaging techniques are used, then device performance is maintained, but manufacturing cost increases
Solution Approach 1:
The alignment mark formation process is merged with the standard substrate preparation流程. The same photolithography and etching tools used for device fabrication are utilized to create the alignment marks, eliminating the need for separate alignment mark fabrication equipment and reducing overall manufacturing cost.
Solution Approach 2:
The alignment marks serve multiple functions: they provide alignment references for both substrates, define bonding registration points, and can potentially serve as test structures for process validation. This multi-functionality reduces the need for separate dedicated alignment features and simplifies the overall manufacturing process.
Data Source
AI summary
A method for aligning multiple substrates. The method includes providing a handle substrate, providing a spacer substrate, and forming a plurality of first alignment marks on a first surface of the handle substrate. The method also includes forming a plurality of self-limiting alignment marks on a first surface of the spacer substrate and forming a plurality of openings in the spacer substrate, each of the plurality of openings surrounded by standoff regions. The method further includes aligning the first surface of the handle substrate and the first surface of the spacer substrate using the first alignment marks and the self-limiting alignment marks and bonding the handle substrate to the spacer substrate to form a composite substrate structure. In a specific embodiment, the plurality of self-limiting alignment marks and the plurality of openings are formed using an anisotropic wet etching process that preferentially etches the spacer substrate.