Roughened Substrate Cavities for Getter Efficiency
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Solution Overview
Problem
The efficiency of the gettering process in MEMS devices is limited by the capacity of the cap wafer to absorb residual gases, which affects the vacuum quality and subsequently the device's operation.
Innovation Solution
A method involving the formation of cavities with roughened interior surfaces on the substrate, where a getter layer is deposited to increase the surface area for gas absorption, enhancing the gettering efficiency by using etchants like xenon difluoride or sulfur hexafluoride, or depositing corrugated materials such as spin-on-glass to create uneven surfaces for the getter layer to trap residual gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a standard flat substrate surface is used for getter layer deposition, then the manufacturing process is simple, but the gettering efficiency is limited due to insufficient surface area for gas absorption
Solution Approach 1:
The patent applies curvature by creating a roughened substrate surface with undulating topography instead of a flat surface. The substrate surface includes peaks and valleys that increase the effective surface area available for getter layer deposition, thereby enhancing gas absorption capacity without fundamentally changing the manufacturing process flow
Solution Approach 2:
The patent creates a porous-like structure on the substrate surface through chemical etching processes. The roughened surface exhibits micro-cavities and irregularities that increase surface area and provide additional sites for gas molecule adsorption, mimicking the behavior of porous materials while maintaining a solid substrate structure
2Reliability
If the substrate surface area is increased to improve gas absorption capacity, then the vacuum quality improves, but the manufacturing complexity increases
Solution Approach 1:
The patent changes the surface parameters of the substrate by controlling etching depth, roughness amplitude, and feature size distribution. These parameter adjustments optimize the surface area-to-volume ratio to enhance gas absorption while maintaining compatibility with existing manufacturing capabilities and process integration
Solution Approach 2:
The patent performs preliminary surface roughening treatment on the substrate before depositing the getter layer. This preliminary action creates the enhanced surface area structure in advance, allowing the subsequent getter layer deposition to proceed using standard processes while benefiting from the pre-prepared high-surface-area substrate
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 increased surface area of the roughened substrate allows for more efficient absorption of residual gases, improving the vacuum quality within the MEMS device chamber and enhancing the device's operational performance.
Implementation Method 1
When a residual gas molecule within the processing chamber comes into contact with a vaporized gettering molecule, the residual gas molecule will combine with the vaporized gettering molecule. The combined gas molecule and gettering molecule are subsequently deposited on the substrate, thereby removing the gas molecule from the vacuum.
Implementation Method 2
The roughened interior surfaces of the one or more cavities enable the substrate to more effectively absorb the residual gases, thereby increasing the efficiency of the gettering process.
Implementation Method 3
Gettering may be performed within a processing chamber by using a vapor deposition technique to deposit a getter layer comprising a plurality of gettering molecules.
Implementation Method 4
using etchants like xenon difluoride or sulfur hexafluoride, or depositing corrugated materials such as spin-on-glass to create uneven surfaces for the getter layer to trap residual gases
Data Source
AI summary
The present disclosure relates to a method of gettering that provides for a high efficiency gettering process by depositing a gettering material on a roughened substrate surface, and an associated apparatus. In some embodiments, the method is performed by providing a substrate into a processing chamber having residual gases. One or more cavities are formed in the substrate at locations between bonding areas on a top surface of the substrate. Respective cavities have roughened interior surfaces that vary in a plurality of directions. A getter layer is deposited into the one or more cavities. The roughened interior surfaces of the one or more cavities enable the substrate to more effectively absorb the residual gases, thereby increasing the efficiency of the gettering process.