Tilted Cavity Cap for MEMS Mirror Ghost Beam Reduction
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Solution Overview
Problem
Conventional LIDAR systems face inaccuracies due to static reflection from the MEMS micro-mirror, causing 'ghost' beams and blurring in the return image, which are not effectively addressed by existing technologies.
Innovation Solution
A MEMS package assembly with a tilted glass cavity cap that reduces static reflection by angling the transmission surface between 5°-30° relative to the MEMS chip surface, minimizing light reflection back onto the micro-mirror.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional MEMS package with a flat cavity cap is used, then the manufacturing process is simple and alignment is easy, but static reflection causes ghost beams and blurring in the LIDAR return image
Solution Approach 1:
The cavity cap is designed with an asymmetrical shape where the transmission surface is tilted at an angle (e.g., 5-30 degrees) relative to the base surface. This asymmetry causes reflected light to diverge away from the optical path, eliminating ghost beams and blurring while maintaining manufacturing feasibility through standard semiconductor fabrication processes
Solution Approach 2:
The tilt angle of the transmission surface is optimized within a specific range (5-30 degrees) to achieve optimal reduction of static reflection. This parameter optimization balances the need to eliminate ghost beams with considerations for manufacturing complexity and optical performance
2Reliability
If the cavity cap transmission surface is tilted at an angle to reduce static reflection, then ghost beams and blurring are minimized, but manufacturing and alignment become more complex
Solution Approach 1:
The cavity cap is integrated with the MEMS chip as a single bonded structure rather than separate components. This segmentation approach allows the tilted transmission surface to be fabricated using standard semiconductor processing techniques, simplifying manufacturing while maintaining the asymmetrical geometry needed to reduce static reflection
Solution Approach 2:
The cavity cap is bonded directly to the MEMS chip to form an integrated package structure. This merging of components eliminates the need for separate alignment steps and simplifies manufacturing, while the asymmetrical shape with tilted transmission surface continues to effectively reduce static reflection and ghost beams
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 cavity cap design significantly reduces static reflection, enhancing the accuracy of LIDAR systems by minimizing 'ghost' beams and blurring, thereby improving the overall performance and reliability of the MEMS mirror's oscillation and image clarity.
Implementation Method 1
a transmission surface of the cavity cap, through which the light and the reflected light is transmitted, is tilted at a tilt angle with respect to the front-side surface of the MEMS chip
Data Source
AI summary
A microelectromechanical system (MEMS) package assembly and a method of manufacturing the same are provided for Light Detection and Ranging (LIDAR) systems. A MEMS package assembly includes a MEMS chip including a front-side surface and a back-side surface, the MEMS chip further including a LIDAR MEMS mirror configured to receive light and reflect the light as reflected light; and a cavity cap disposed on the front-side surface of the MEMS chip and forms a cavity that surrounds the LIDAR MEMS mirror such that the LIDAR MEMS mirror is sealed from an environment, the cavity cap having an asymmetrical shape such that a transmission surface of the cavity cap, through which the light and the reflected light is transmitted, is tilted at a tilt angle with respect to the front-side surface of the MEMS chip.