MEMS Sensor Epitaxial Electrode Structure for Simpler Signal Extraction
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Solution Overview
Problem
The manufacturing process of MEMS sensors is complicated due to the need for wirings and contacts to extract electric signals, and there is a desire to improve sensitivity.
Innovation Solution
A MEMS sensor design that includes a first substrate with a cavity, electrodes, a support portion, and an epitaxial growth layer with monocrystalline and polycrystalline portions, allowing direct electrical connection through the epitaxial growth layer to a second substrate, eliminating the need for separate wirings and contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wirings and contacts are formed to take out electric signals from electrodes, then electrical connection is achieved, but manufacturing process becomes complicated
Solution Approach 1:
The patent merges the functions of the epitaxial growth layer, wiring, and contact into a single integrated structure. The epitaxial growth layer is formed to have both a monocrystalline portion (serving as electrode extension) and a polycrystalline portion (serving as contact), eliminating the need for separate wiring and contact formation steps.
Solution Approach 2:
The epitaxial growth layer serves multiple functions simultaneously: it provides electrical connection through the monocrystalline portion, provides bonding surface through the polycrystalline portion, and acts as both electrode extension and contact structure. This multi-functionality reduces the number of separate components needed.
2Reliability
If conventional wiring and contact structure are used, then electrical connection is established, but sensor sensitivity is reduced
Solution Approach 1:
The patent applies different crystal structures in different locations of the epitaxial growth layer: the monocrystalline portion is used where high electrical conductivity and low noise are needed (near the electrode), while the polycrystalline portion is used where mechanical bonding is needed. This local differentiation optimizes both sensitivity and connection reliability.
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 design simplifies the manufacturing process while improving sensor sensitivity by using the epitaxial growth layer to connect electrodes directly to the second substrate, enhancing the electrical connection.
Implementation Method 1
an epitaxial growth layer formed on the electrode and the element isolation portion of the first substrate; and the epitaxial growth layer has a monocrystalline portion arranged on the electrode and a polycrystalline portion arranged on the element isolation portion
Data Source
AI summary
A MEMS sensor includes: a first substrate having a cavity partially exposed on the surface of the first substrate; an electrode of a sensor element provided on the first substrate and arranged in the cavity; a support portion provided on the first substrate and configured to support the electrode; an element isolation portion formed on the first substrate so as to cover the support portion and configured to electrically isolate the electrode and the support portion from each other; an epitaxial growth layer formed on the electrode and the element isolation portion of the first substrate; and a second substrate bonded to the first substrate and configured to cover the sensor element, wherein the epitaxial growth layer has a monocrystalline portion arranged on the electrode and a polycrystalline portion arranged on the element isolation portion.