Silicide Electrode Formation in Capacitive MEMS Pressure Sensors
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Solution Overview
Problem
Capacitive MEMS pressure sensors face issues with mechanical stability and aging due to metal layers deposited on the top surface, which affect sensor properties and require additional processing steps for electrical connections.
Innovation Solution
The formation of silicide portions in the cap layer of a silicon on insulator (SOI) wafer, eliminating the need for an applied metal layer by depositing silicide-forming metal and annealing it to create a conductive and mechanically stable interface between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer is deposited on the top surface of the sensor device to provide electrical connections, then electrical conductivity is improved, but mechanical stability deteriorates leading to aging and drifting sensor properties
Solution Approach 1:
The patent changes the material parameter from applied metal layer to silicide layer formed through annealing. The silicide layer is formed by depositing a silicide-forming material and annealing the sensor device, transforming the material state from metallic to silicide, which provides both electrical conductivity and mechanical stability without aging or drifting properties.
2Reliability
If an applied metal layer is used to provide electrical connections to electrodes, then electrical conductivity is improved, but device complexity increases due to additional processing steps
Solution Approach 1:
The patent merges the electrical connection formation with the sensor fabrication process itself. The silicide layer is formed during the same fabrication sequence as the sensor structure, eliminating the need for separate metal layer deposition and patterning steps. This integration reduces device complexity while maintaining reliable electrical connections.
Solution Approach 2:
The silicide-forming material automatically forms conductive connections through the annealing process without requiring additional patterning or connection steps. The material self-organizes to provide electrical pathways during the thermal processing, reducing the need for complex subsequent fabrication steps.
3Ease of operation
If traces are patterned on the top surface to provide individual electrical connections, then electrical connectivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the electrical connection function from the traditional metal trace layer and integrates it into the silicide layer formed during sensor fabrication. This eliminates the need for separate trace patterning operations, simplifying the manufacturing process while maintaining the capability for individual electrical connections to sensor components.
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 enhances mechanical stability and conductivity while eliminating the need for additional processing steps, improving the reliability and manufacturing efficiency of capacitive MEMS sensors.
Implementation Method 1
depositing a silicide-forming metal on a top surface of the silicon cap layer
Implementation Method 2
annealing the deposited silicide-forming metal to form a silicide portion in the silicon cap layer
Implementation Method 3
a silicide portion formed in the cap layer... enhancing mechanical stability and conductivity
Data Source
AI summary
A system and method for forming a sensor device includes defining an in-plane electrode in a device layer of a silicon on insulator (SOI) wafer, forming an out-of-plane electrode in a silicon cap layer located above an upper surface of the device layer, depositing a silicide-forming metal on a top surface of the silicon cap layer, and annealing the deposited silicide-forming metal to form a silicide portion in the silicon cap layer.