Tilted MEMS Chip Assembly for LIDAR Static Reflection
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Solution Overview
Problem
Current LIDAR systems with mechanical moving mirrors face inaccuracies due to static reflection, leading to a non-planar package outline that complicates automatic board assembly and results in 'blurring' in return images.
Innovation Solution
A tilted chip assembly is implemented in the MEMS package, where the MEMS chip is oriented at a specific angle with respect to the substrate, and a transparent plate is used above it to reduce static reflections, allowing for improved light transmission and assembly simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tilted protective glass is arranged over a MEMS micro-mirror to reduce static reflection, then measurement precision is improved, but device complexity increases due to non-planar package outline
Solution Approach 1:
Instead of tilting the protective glass over a planar MEMS chip (which creates non-planar package outline), the patent inverts the approach by keeping the protective glass planar and tilting the MEMS chip itself. This inversion resolves the contradiction by maintaining measurement precision through tilt while achieving a planar package outline that simplifies device complexity and automated assembly.
Solution Approach 2:
The patent changes the dimension of tilting from the protective glass layer to the MEMS chip layer. By tilting the chip in the mounting plane rather than tilting the glass cover, the solution achieves the anti-reflection function while maintaining a planar top surface, effectively moving the tilting operation to a different dimensional level in the assembly hierarchy.
2Reliability
If a tilted protective glass is used to reduce static reflection, then reliability is improved by minimizing light interference, but ease of manufacture deteriorates due to complicated assembly process
Solution Approach 1:
The patent inverts which component is tilted: instead of tilting the protective glass, it tilts the MEMS chip while keeping the glass planar. This inversion significantly improves ease of manufacture because planar components are much easier to handle, position, and assemble automatically, while still achieving the reliability benefit of reduced static reflection through the chip tilt.
Solution Approach 2:
The patent introduces a wedge-shaped adhesive layer as an intermediary element between the planar substrate and the MEMS chip. This adhesive mediator enables the chip to be tilted at the required angle while maintaining a planar package outline, facilitating easier manufacturing and assembly compared to directly tilting the protective glass.
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 tilted chip assembly reduces static reflections, enhancing the accuracy of LIDAR systems by minimizing light interference and facilitating a more straightforward assembly process.
Implementation Method 1
a transparent plate disposed above and parallel to the substrate and is configured to permit a transmission of light therethrough
Implementation Method 2
The glass is tilted in order to reduce the amount of light reflected off the back side of the glass back onto the MEMS micro-mirror, referred to as static reflection
Data Source
AI summary
A microelectromechanical systems (MEMS) package assembly and a method of manufacturing the same is provided. The MEMS package assembly includes a substrate, a housing coupled to the substrate to form a cavity, wherein the housing includes a transparent plate disposed above and parallel to the substrate and is configured to permit a transmission of light therethrough, and a MEMS chip disposed within the cavity and including a first main surface proximal to the transparent plate and a second main surface opposite to the first main surface and coupled to the substrate. The MEMS chip is oriented such that the first main surface is tilted at a tilt angle with respect to the transparent plate.