Direct-Bonded Silicon MEMS Structure Without Via Electrodes
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Solution Overview
Problem
Existing MEMS devices face challenges in size reduction due to the need for via electrodes and side etching to ensure movable electrode ranges, which complicates miniaturization.
Innovation Solution
A MEMS device configuration using single-crystal silicon substrates joined directly without an intervening silicon oxide layer, allowing for electrostatic capacity changes based on distance, eliminating the need for via electrodes and side etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a silicon oxide layer is laminated on a Si substrate at the electrostatic capacity portion, then the movable range of electrodes is ensured, but via electrodes are required which increase device size
Solution Approach 1:
The patent removes the silicon oxide layer from the electrostatic capacity portion, extracting the problematic element that necessitated via electrodes. By eliminating this layer, the invention directly removes the requirement for via electrodes, thereby reducing device size while preserving the necessary movable range through alternative structural design.
Solution Approach 2:
The patent merges the Si substrate directly with the Si film without an intervening silicon oxide layer. This direct bonding approach eliminates the need for separate via electrode structures, combining multiple functions into a more integrated and compact configuration that reduces overall device footprint.
2Length of moving object
If side etching is executed for the silicon oxide layer, then the movable range of electrodes is ensured, but the area of the silicon oxide layer must be sufficiently ensured which prevents size reduction
Solution Approach 1:
The patent extracts and removes the silicon oxide layer from the electrostatic capacity portion, eliminating the need for side etching processes. This direct removal approach simplifies the manufacturing process by avoiding complex etching steps while still ensuring adequate movable range through the redesigned structure.
Solution Approach 2:
The patent changes the structural parameters by eliminating the silicon oxide layer entirely from the electrostatic capacity portion. This parameter change transforms the manufacturing approach from one requiring precise side etching control to a simpler process that achieves the same functional outcome with reduced complexity.
3Reliability
If via electrodes are disposed to electrically connect the Si substrate to a Si film, then electrical connection is achieved, but disposing space is required which prevents size reduction
Solution Approach 1:
The patent merges the Si substrate directly with the Si film through direct bonding without an intervening silicon oxide layer. This merging eliminates the need for separate via electrode structures, achieving reliable electrical connection through direct contact while significantly reducing the space required for connections.
Solution Approach 2:
The patent extracts and eliminates the silicon oxide layer that previously necessitated via electrodes. By removing this intermediate layer, the invention achieves direct electrical connection between substrates, eliminating the need for additional via electrode components and their associated disposing space.
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
Enables size reduction by eliminating the need for via electrodes and side etching, improving detection accuracy and movement range, and facilitating miniaturization.
Implementation Method 1
the single-crystal silicon of the second substrate being joined to the single-crystal silicon of the first substrate
Implementation Method 2
an electrostatic capacity portion between at least one of (1) the second cover and the second substrate or (2) the first substrate and the second substrate, the electrostatic capacity portion being configured such that electrostatic capacity changes depending on a distance between the movable portion and the second cover or the first substrate
Data Source
AI summary
A MEMS device that includes: a first cover; a second cover defining a space between the second cover and the first cover; a first substrate opposite to the first cover in the space between the second cover and the first cover, the first substrate comprising single-crystal silicon; a second substrate opposite to the second cover in the space between the second cover and the first cover, the second substrate comprising single-crystal silicon, the second substrate including a movable portion, the single-crystal silicon of the second substrate being joined to the single-crystal silicon of the first substrate; and an electrostatic capacity portion between at least one of (1) the second cover and the second substrate or (2) the first substrate and the second substrate, the electrostatic capacity portion being configured such that electrostatic capacity changes depending on a distance between the movable portion and the second cover or the first substrate.