Hydrogenated Amorphous Silicon Outgas Layer for MEMS Pressure Control
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Solution Overview
Problem
The challenge in forming integrated microelectromechanical systems (MEMS) devices on a single substrate is that the outgas layer depletes its outgas species before bonding, leading to a failure in maintaining the desired gas pressure within the MEMS cavities, which affects the quality, stability, and endurance of the devices.
Innovation Solution
An improved outgas layer using hydrogenated amorphous silicon (a-Si:H) with a high composition of hydrogen is employed, which continues to outgas species at high temperatures, ensuring the maintenance of the gas pressure within the MEMS cavities even after bonding and fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional outgas layer materials are used, then the bonding process can be completed, but the outgas layer depletes its outgas species before bonding, leading to failure in maintaining desired gas pressure within MEMS cavities
Solution Approach 1:
The patent changes the material parameter of the outgas layer from conventional materials to hydrogenated amorphous silicon (a-Si:H), which has a fundamentally different outgas behavior. This material parameter change enables continuous outgassing at high temperatures (above 400°C) without depletion, directly resolving the contradiction between maintaining gas pressure and preserving outgas species quantity through the bonding process
Solution Approach 2:
The patent employs hydrogenated amorphous silicon (a-Si:H), which is a composite material structure combining silicon with hydrogen atoms. This composite structure allows the material to maintain its outgassing capability at high temperatures while providing structural stability during bonding, thus simultaneously achieving reliable gas pressure maintenance and preserving outgas species availability
2Strength
If high temperature bonding is performed, then strong bonding is achieved, but the outgas layer depletes outgas species before bonding completes
Solution Approach 1:
The patent changes the thermal parameter behavior of the outgas layer by selecting hydrogenated amorphous silicon (a-Si:H), which maintains its outgassing function at high temperatures (above 400°C) required for strong bonding. This parameter change allows the system to achieve both strong bonding strength and continued gas pressure maintenance during and after the bonding process
3Reliability
If outgas species are released early, then gas pressure is maintained initially, but the outgas layer depletes before bonding, causing pressure maintenance failure
Solution Approach 1:
The patent fundamentally changes the thermal stability parameter of the outgas layer material to hydrogenated amorphous silicon (a-Si:H), which enables the outgassing action to continue at high temperatures throughout the entire bonding process and beyond. This extends the duration of outgas layer functionality from before-bonding to post-bonding, ensuring continuous gas pressure maintenance throughout the complete fabrication process
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 solution enhances the quality factor, stability, and endurance of the MEMS devices by maintaining the desired gas pressure, improving the performance and reliability of the integrated chip.
Implementation Method 1
An improved outgas layer using hydrogenated amorphous silicon (a-Si:H) with a high composition of hydrogen is employed, which continues to outgas species at high temperatures
Data Source
AI summary
Various embodiments of the present disclosure are directed towards an integrated chip including a microelectromechanical systems (MEMS) structure overlying a substrate. A capping structure overlies the MEMS structure. The capping structure at least partially defines a cavity. The MEMS structure is disposed in the cavity. An outgas structure adjacent to the cavity. The outgas structure comprises an amorphous material.