MEMS Pressure Sensor Boss Structure Design
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Solution Overview
Problem
Existing MEMS pressure sensor devices require high manufacturing costs and limited design flexibility due to complex lithography and etching processes, which result in misalignment issues and restricted shape options for the boss structure, making them costly and less effective for sensing lower pressures.
Innovation Solution
A MEMS pressure sensor device with a substrate featuring recesses forming a boss, a bonded membrane, and a sensing unit, where the first opening is created using a deep reactive ion etching or polishing process on a flat lower surface, allowing for adjusted boss thickness and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two lithography processes are used to create a thinner membrane with a boss, then sensitivity and linear operation region are improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent divides the manufacturing process into two independent stages: first forming the boss structure through selective etching, then bonding the membrane separately. This segmentation eliminates the need for complex alignment between multiple lithography processes while achieving the same thin membrane with boss structure that improves pressure sensing capability.
Solution Approach 2:
The boss structure is formed in advance through selective etching before membrane bonding. This preliminary action allows the membrane to be bonded to a pre-formed boss structure without requiring complex alignment during the bonding process, thereby reducing manufacturing complexity while maintaining sensitivity.
2Manufacturing precision
If anisotropic etching is used to form the boss, then etching precision is improved, but design flexibility and shape options are limited
Solution Approach 1:
The patent changes the etching parameter from anisotropic to isotropic etching. Although isotropic etching has lower directional precision, it provides complete design flexibility for the boss structure shape. The boss structure is then refined through controlled etching time and chemical composition to achieve the desired thickness and shape without being constrained by crystallographic directions.
Solution Approach 2:
The patent introduces a sacrificial layer as an intermediary element that enables flexible boss structure formation. The sacrificial layer is deposited conformally and then selectively removed to create the boss structure with any desired shape, decoupling the design flexibility from the etching process limitations.
3Measurement precision
If the substrate surface is made rugged with trenches, then pressure distribution is improved, but alignment accuracy for subsequent lithography deteriorates
Solution Approach 1:
Instead of forming trenches first and then attempting to align subsequent lithography layers, the patent inverts the sequence: the boss structure is formed first through selective etching, and then the membrane is bonded to this pre-formed structure. This eliminates the alignment problem entirely by removing the requirement for complex lithography alignment on a rugged surface.
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 reduces manufacturing costs, eliminates misalignment issues, and enhances design flexibility, enabling the device to sense lower pressures with improved sensitivity and wider application possibilities.
Implementation Method 1
forming a first opening on a lower surface of the substrate by an etching process or a polishing process
Implementation Method 2
at least one sensing unit, which is coupled to the membrane for sensing deflection of the membrane
Data Source
AI summary
The present invention discloses a Micro-Electro-Mechanical System (MEMS) pressure sensor device and a manufacturing method thereof. The MEMS pressure sensor device includes: a substrate having at least one recess formed on an upper surface thereof, the recess defining a boss; a membrane, which is bonded to at least a part of the upper surface and at least a part of the boss, so that the at least one recess forms a cavity; at least one sensing unit, which is coupled to the membrane, for sensing deflection of the membrane; and an opening, which is formed on a lower surface of the substrate, and connects to the cavity.