Suspended MEMS Electrode via Dielectric Intermediary
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Solution Overview
Problem
Current methods for manufacturing MEMS/NEMS with electrodes face challenges such as limited material choices due to the need for conductive active layers, high aspect ratio etching complexities, and costly alignment processes, which restrict the use of hot processes and increase component reliability defects.
Innovation Solution
A device and method involving a first substrate with a movable part, a conductive lower electrode, and a dielectric layer between the substrates, where through vias filled with conductive material connect the lower electrode, allowing for capacitive detection and enabling the use of various active layers and substrates, and self-aligned interconnections without specific alignment equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal seals are used to connect lower and upper electrodes, then electrical connection is achieved, but hot processes such as thermal oxidation cannot be performed subsequently
Solution Approach 1:
The patent extracts the sealing function from the metal seal layer and relocates it to the dielectric layer. The dielectric layer is deposited over the lower electrode and patterned to expose contact regions, eliminating the need for metal seals and enabling subsequent hot processes like thermal oxidation while maintaining electrical connection reliability through the dielectric's inherent properties
Solution Approach 2:
The dielectric layer serves as an intermediary between the lower electrode and the upper electrode structure. It provides both electrical insulation and mechanical support, allowing hot processes to be performed without compromising the electrical connection, thus resolving the contradiction between connection reliability and process flexibility
2Reliability
If deep etching vias are used to reach lower electrodes, then electrical connection is established, but the process becomes costly and difficult to control in high aspect ratio cases
Solution Approach 1:
The patent applies preliminary action by forming the dielectric layer and patterned contact regions before performing the etching process. This preliminary structuring guides the etching depth and path, making the process easier to control even in high aspect ratio cases, while maintaining reliable electrical connection through the precisely defined contact regions
3Reliability
If active layer serves as interconnect to raise contact from bottom electrode, then connection is achieved, but material choice is limited due to conductivity requirements
Solution Approach 1:
The patent segments the interconnection function from the active layer by introducing separate contact regions in the dielectric layer. This allows the active layer to be optimized for its primary function (MEMS operation) while the dielectric contact regions provide the necessary electrical interconnection, eliminating conductivity restrictions on active layer material selection and enabling greater versatility
Solution Approach 2:
The dielectric layer with patterned contact regions acts as an intermediary that decouples the electrical interconnection function from the active layer. This mediator allows any material to be used for the active layer without conductivity constraints, as the dielectric contact regions provide the necessary electrical pathway, thus resolving the contradiction between interconnection reliability and material selection flexibility
4Manufacturing precision
If alignment marks on underside of support substrate are used, then alignment between lower electrodes and MEMS structure is achieved, but specific alignment equipment and additional technological steps are required
Solution Approach 1:
The patent implements self-service by making the dielectric layer and its contact regions self-aligning with the lower electrodes. The patterned contact regions are formed directly over the lower electrode structures, automatically providing alignment without requiring external alignment marks or specialized alignment equipment, thus achieving high manufacturing precision while reducing process complexity
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 simplifies the manufacturing process, increases component reliability, and allows for a wide range of active layers and substrates, enabling efficient capacitive detection with improved sensitivity and reduced costs by eliminating the need for specific alignment equipment and hot processes.
Implementation Method 1
capacitive detection and enabling the use of various active layers and substrates
Data Source
Figure 1
Figure 2A~2C
Figure 2D~2E
AI summary
The device has an intermediate substrate (100) including a movable mass (120), and a support substrate (200) including a lower electrode (102) defined in a bottom electrode layer, and a dielectric layer (101) placed between the substrates. A portion of the dielectric layer is removed to form a cavity in the movable mass, where the bottom of the cavity is constituted by an upper surface of a portion of the lower electrode facing a portion of the movable mass. The intermediate substrate includes a through via (111) filled with a conductive material in contact with the lower electrode. The intermediate substrate is made of a semiconductor material such as silicon or silicon germanium (SiGe) or silicon carbide (SiC) or silicon-germanium-carbon (SiGeC) or gallium arsenide (GaAs) or germanium (Ge). An independent claim is also included for a method for making a microsystem and/or nanosystem type device.