MEMS CMOS Integration with Variable Height Protrusions
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Solution Overview
Problem
Conventional MEMS sensor technologies face challenges in reducing sensing air gaps to enhance sensitivity, as it negatively affects the performance of other sensors, leading to compromised overall device performance.
Innovation Solution
The integration of a MEMS substrate with protrusions of different heights with a CMOS substrate, using etching techniques with multiple photoresist masks to create and adjust these protrusions, allowing for tailored sensing air gaps that improve sensitivity while maintaining or increasing other air gaps, thereby optimizing sensor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing air gap is reduced to increase capacitive sensitivity, then the sensitivity of the accelerometer is improved, but the performance of other sensors in the MEMS device is negatively affected
Solution Approach 1:
The patent applies local quality by creating protrusions of different heights at different locations on the MEMS substrate. Specifically, first protrusions have a first height that provides a first sensing air gap for accelerometers, while second protrusions have a second height that provides a second sensing air gap for other sensors. This allows each sensor type to have optimized local conditions for its specific performance requirements.
Solution Approach 2:
The patent segments the uniform substrate surface into multiple regions with different protrusion heights. The MEMS substrate is divided into areas with first protrusions and areas with second protrusions, allowing different sensing air gaps to be created for different sensor types. This segmentation enables independent optimization of sensing conditions for each sensor category.
2Measurement precision
If the sensing air gap is reduced to enhance sensitivity, then the sensitivity of specific sensors is improved, but the overall device performance is compromised
Solution Approach 1:
Different regions of the MEMS substrate are given different local properties through protrusions of varying heights. Accelerometer regions have protrusions with a first height optimized for capacitive sensitivity, while other sensor regions have protrusions with a second height optimized for their specific performance requirements, allowing each area to have locally optimal characteristics.
Solution Approach 2:
The substrate is segmented into multiple functional zones with different protrusion heights, allowing sensitivity optimization for specific sensors without compromising the overall device. The segmentation enables parallel optimization of different sensor types on the same substrate.
Data Source
AI summary
A device comprising a micro-electro-mechanical system (MEMS) substrate with protrusions of different heights that has been integrated with a complementary metal-oxide-semiconductor (CMOS) substrate is presented herein. The MEMS substrate comprises defined protrusions of respective distinct heights from a surface of the MEMS substrate, and the MEMS substrate is bonded to the CMOS substrate. In an aspect, the defined protrusions can be formed from the MEMS substrate. In another aspect, the defined protrusions can be deposited on, or attached to, the MEMS substrate. In yet another aspect, the MEMS substrate comprises monocrystalline silicon and/or polysilicon. In yet even another aspect, the defined protrusions comprise respective electrodes of sensors of the device.