MEMS Mirror Arrays Using Segmented Sub-dies for Yield Optimization
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Solution Overview
Problem
As optical cross-connect systems grow in size, monolithic MEMS mirror arrays become impractical due to yield losses from non-functioning or under-rotating mirrors, leading to increased size and complexity, and wastage of wafer space.
Innovation Solution
The implementation of MEMS mirror arrays composed of multiple independent mirror units with sub-dies, where interior mirror units have a greater number of MEMS mirrors and a smaller angular rotation range, and exterior units have fewer mirrors with a larger rotation range, allowing for a more efficient use of space and reducing the complexity of actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If monolithic MEMS mirror arrays are used to increase system size, then the number of mirrors increases, but yield loss increases due to non-functioning or under-rotating mirrors
Solution Approach 1:
The patent divides the monolithic MEMS mirror array into multiple independent mirror units, each fabricated on separate dies. This segmentation allows individual units to be tested and selected based on functionality, improving overall yield while achieving the required number of mirrors for larger system sizes.
2Quantity of substance
If mirror aperture size and pitch are increased to accommodate more mirrors, then the number of mirrors increases, but the linear length consumed per mirror increases
Solution Approach 1:
The patent transitions from a single-plane monolithic array to a multi-dimensional arrangement using multiple stacked dies. This allows mirrors to be organized in three-dimensional space, increasing the effective number of mirrors without proportionally increasing the linear footprint on a single wafer.
3Quantity of substance
If wafer size is increased to support larger mirror arrays, then the number of mirrors increases, but wafer space utilization decreases
Solution Approach 1:
By segmenting the mirror array into multiple smaller dies that can be stacked, the patent achieves high mirror counts without requiring proportionally larger individual wafers. Each die can be optimized for its specific function, improving space utilization.
Solution Approach 2:
The patent implements a nested structure where multiple dies are stacked vertically, with interior dies containing mirrors that have smaller rotation ranges and exterior dies containing mirrors with larger rotation ranges. This nesting maximizes the use of available wafer space across multiple layers.
4Adaptability or versatility
If all mirrors are designed with maximum rotation range, then angular coverage is improved, but device complexity and actuator requirements increase
Solution Approach 1:
The patent applies different rotation range requirements to different spatial locations within the mirror array. Interior mirrors, which serve central viewing zones, have smaller rotation ranges with simpler actuators, while exterior mirrors serve peripheral zones and have larger rotation ranges. This local differentiation reduces overall system complexity.
Solution Approach 2:
The patent creates a dynamic hierarchy where mirrors are assigned different operational ranges based on their position and function. This allows the system to optimize performance for each zone while reducing the complexity burden that would result from uniform maximum rotation ranges across all mirrors.
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 approach reduces the overall size of the MEMS mirror arrays, improves yield, conserves materials, and simplifies testing by allowing sub-dies with insufficient rotation to be used in the interior rather than discarded, thereby enhancing the performance and efficiency of optical cross-connect systems.
Implementation Method 1
MEMS mirrors supported by a common substrate between the interior and exterior mirror units. The MEMS mirrors can be rotated using actuators to align the optical signals onto the appropriate fibers.
Data Source
AI summary
A micro-electro-mechanical systems (MEMS) mirror array can be constructed using sub-dies that each includes two or more MEMS mirrors. In some implementations, an optical cross-connect system includes a first MEMS mirror array that includes first mirror units. Each first mirror unit can include a first substrate and two or more first MEMS mirrors supported by the first substrate. Each first substrate can be independent from each other first substrate. The cross-connect system can include a second MEMS mirror array that includes second mirror units. Each second mirror unit can include a second substrate and two or more second MEMS mirrors supported by the second substrate. Each second substrate can be independent from each other second substrate.