MEMS Bonding Pad Rings for Low Thermal Budget Sealing
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Solution Overview
Problem
In micro electro mechanical system (MEMS) package systems, insufficient thermal budget during bonding can result in incomplete sealing of MEMS devices, leading to malfunction, while excessive thermal budget can cause issues like metal melting and short circuits in CMOS transistors.
Innovation Solution
The use of multiple, narrow bond pad rings with recesses on both the device and handle substrates, which require a lower thermal budget for eutectic bonding, reducing the risk of metal melting and ensuring complete sealing of MEMS devices without damaging CMOS components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high thermal budget is used during bonding, then complete sealing of MEMS devices is achieved, but metal melting and short circuits in CMOS transistors occur
Solution Approach 1:
The bonding pad structure is divided into multiple narrow rings instead of a single wide pad. This segmentation reduces the total bonding area and distributes the thermal load, enabling complete sealing at lower thermal budgets that do not damage CMOS transistors
Solution Approach 2:
The bonding pads are positioned at specific locations away from CMOS transistor regions. This local placement strategy concentrates the thermal budget application in non-sensitive areas, achieving complete sealing while protecting vulnerable CMOS components from thermal damage
2Object-affected harmful factors
If a low thermal budget is used during bonding, then CMOS transistors are protected from thermal damage, but sealing of MEMS devices is incomplete
Solution Approach 1:
Multiple narrow bonding pad rings provide sufficient bonding interface area distributed across the package, achieving complete sealing even with reduced thermal budget. The segmented structure maintains effective bonding without requiring excessive heat that would damage CMOS
Solution Approach 2:
The bonding pad structure is pre-configured with multiple narrow rings optimized for lower thermal budget bonding. This preliminary design ensures that the bonding process can achieve complete sealing at reduced temperatures, preventing the need for high thermal budgets that would harm CMOS
3Area of stationary object
If wide bonding pad rings are used, then bonding area is increased, but thermal budget increases causing metal melting
Solution Approach 1:
The total bonding area is divided into multiple narrow rings instead of one wide pad. This segmentation achieves the required bonding area while reducing the thermal mass and thermal budget, preventing metal melting in the bonding region
Solution Approach 2:
Instead of increasing bonding area by making pads wider (one dimension), the solution uses multiple rings distributed in space (adding spatial distribution dimension). This approach achieves sufficient bonding area without concentrating excessive thermal energy in a single location
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 approach ensures reliable sealing of MEMS devices within the package system while minimizing the risk of thermal damage to CMOS transistors, thereby enhancing the functionality and reliability of MEMS devices.
Implementation Method 1
The bonding pad structure is bonded with the handle substrate. In an embodiment, the bonding pad structure is eutectically bonded with the handle substrate
Data Source
AI summary
A method of fabricating a micro electro mechanical system (MEMS) structure includes providing a first substrate structure including a bonding pad structure. The bonding pad structure has at least one recess therein. A second substrate structure is provided and bonded with the bonding pad structure of the first substrate structure.