Lateral Vent Hole Structure for MEMS Device Manufacturing
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Solution Overview
Problem
Current MEMS device manufacturing processes are cumbersome due to the need to etch through thick silicon substrates to create vent holes, which inhibits air compression and movement of sealed meshes, making it difficult to fabricate microspeakers and microphones effectively.
Innovation Solution
A MEMS device with a lateral vent hole structure on the same side of the substrate as the MEMS structure, utilizing a metal layer with vent holes surrounded by etch stop structures, allowing simultaneous release of the vent hole and micro-machined metal mesh, and using dielectric etching which is faster than silicon etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vent holes are formed by boring through the silicon substrate from the rear, then the sealed mesh can function as a movable plate, but the manufacturing process becomes tedious and time-consuming due to the thick substrate (700 microns)
Solution Approach 1:
The patent changes the dimension of vent hole formation from vertical (through the thick substrate from the rear) to lateral (through dielectric layers on the same side as the MEMS structure). This dimensional shift allows vent holes to be formed much more quickly since dielectric layers are much thinner than the 700-micron substrate, resolving the time-consuming etching problem while maintaining sealed mesh functionality.
Solution Approach 2:
The patent introduces dielectric layers as an intermediary medium between the substrate and the vent holes. Instead of boring directly through the thick substrate, vent holes are formed through these thinner dielectric layers that are deposited on the substrate surface. This intermediary approach maintains the structural integrity of the substrate while enabling quick vent hole formation.
2Manufacturing precision
If multiple layers are stacked on the substrate for MEMS structure formation, then the device complexity increases, but the manufacturing precision can be improved through better control
Solution Approach 1:
The patent merges the vent hole formation process with the existing multi-layer stacking process. The vent holes are formed laterally through the dielectric layers during the same manufacturing sequence used to build the MEMS structure, rather than as a separate post-processing step. This integration maintains manufacturing precision while avoiding the added complexity of a separate vent hole formation process.
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 by reducing etching time and enabling easier integration with logic structures, facilitating the production of MEMS devices like microphones and microspeakers by allowing air compression and movement.
Implementation Method 1
movement of the sealed mesh inward is inhibited by the inability to compress the air in the chamber
Implementation Method 2
movement of the mesh outward is inhibited by formation of a vacuum
Implementation Method 3
reducing etching time for dielectric materials like silicon oxide
Data Source
AI summary
A MEMS device includes a vent hole structure and a MEMS structure disposed on a same side of a substrate. The vent hole structure adjoins the MEMS structure with an etch stop structure therebetween. The MEMS structure includes a chamber, the vent hole structure includes a metal layer having at least a hole thereon as a vent hole to connect the chamber of the MEMS structure through the etch stop structure. Accordingly, the MEMS device has a lateral vent hole. Furthermore, as the vent hole structure and the MEMS structure are disposed on the same side of the substrate, the manufacturing process is convenient and timesaving.