MEMS Microphone Back-Hole Etching Using Ring Separation Component
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Solution Overview
Problem
Conventional MEMS microphone manufacturing methods result in back-holes with varying contours and tilt angles, leading to increased susceptibility to damage and performance deterioration, particularly at the boundary of the wafer.
Innovation Solution
A microphone manufacturing method involving the formation of a ring opening and separation component on a substrate, followed by etching using a ring separation component and insulation layer as an etch-stop layer to create a back-hole with consistent contours and reduced tilt angles, ensuring uniformity and reducing the risk of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional back-hole formation methods are used, then manufacturing simplicity is maintained, but back-hole contour consistency and surface smoothness deteriorate at wafer boundaries
Solution Approach 1:
A ring-shaped separation component is formed in advance at the boundary between the back-hole region and non-back-hole region before back-hole etching. This preliminary structure serves as a etch-stop layer that prevents lateral etching expansion, ensuring consistent back-hole contours and smooth surfaces even at wafer boundaries where conventional methods produce rough surfaces with notches.
Solution Approach 2:
The ring-shaped separation component is selectively placed only at the boundary region between back-hole and non-back-hole areas, providing localized etch protection where it is most needed. This localized approach improves back-hole contour consistency at critical boundary regions without requiring complex modifications to the entire manufacturing process.
2Productivity
If back-holes are formed on wafer boundary, then substrate utilization is maximized, but vibration film contact quality and damage resistance deteriorate
Solution Approach 1:
The ring-shaped separation component is formed in advance at the wafer boundary region before back-hole etching. This preliminary protective structure ensures that when back-holes are formed at wafer boundaries to maximize substrate utilization, the vibration film still achieves smooth surface contact with the substrate rather than point contact, thereby maintaining damage resistance.
Solution Approach 2:
The ring-shaped separation component acts as a protective cushion that prevents excessive lateral etching from reaching the vibration film at wafer boundaries. By providing this protective barrier in advance, the structure cushions the vibration film from damage while still allowing substrate utilization to be maximized through boundary back-hole formation.
3Productivity
If large tilt angle sidewalls are formed, then etching speed is improved, but overlap region between vibration film and substrate shrinks
Solution Approach 1:
The ring-shaped separation component is formed in advance to establish a controlled etching boundary. This preliminary structure allows the use of faster etching processes that create larger tilt angles while preventing excessive lateral etching from expanding beyond the ring component, thereby maintaining consistent overlap regions between the vibration film and substrate.
Solution Approach 2:
The ring-shaped separation component changes the etching parameters by providing a physical barrier that limits lateral etching expansion. This allows the etching process to proceed with larger tilt angles and higher speeds while the ring component constrains the etching front, maintaining the overlap region size consistent with slower, more controlled etching processes.
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 method enhances the consistency of back-hole formation, reducing the risk of damage to the vibration film and improving the signal-to-noise ratio by maintaining a smooth surface and consistent overlap region between the vibration film and substrate.
Implementation Method 1
the separation material may be formed in the ring opening through a thermal oxidation process, the thermal oxidation process may oxidize the upper surface of the substrate to form an oxidation layer
Implementation Method 2
etching a back side of the substrate using the ring separation component and the insulation layer as an etch-stop layer to form a back-hole
Data Source
AI summary
A microphone and its manufacturing method are presented. The manufacturing method includes providing a substrate; forming a ring opening extending from an upper surface of the substrate into the substrate; forming a ring separation component by forming a separation material in the ring opening; forming an insulation layer on the substrate; forming a front-end device on the insulation layer; and etching a back side of the substrate using the ring separation component and the insulation layer as an etch-stop layer to form a back-hole.