MEMS Cavity Alignment via Metal Ring Etching Mask
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Solution Overview
Problem
The existing manufacturing processes for semiconductor structures with micro-electro-mechanical systems (MEMS) face challenges in achieving precise alignment and stability of cavities relative to sensing membranes, leading to potential product quality issues and increased scrap rates due to alignment shifts during etching processes.
Innovation Solution
A semiconductor structure and manufacturing method that incorporate a metal ring within a dielectric structure, where the metal ring serves as an etching mask to form a cavity aligned with the sensing membrane, allowing for precise pattern formation and increasing the etching process window, thereby enhancing product yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used without a metal ring mask, then the manufacturing process is simpler, but the alignment precision of the cavity relative to the sensing membrane deteriorates
Solution Approach 1:
The patent introduces a metal ring as an intermediary etching mask between the etching process and the dielectric structure. This metal ring serves as a mediator that enables precise alignment of the cavity with the sensing membrane while being removable after serving its purpose. The metal ring is formed in a first etching process, used as a mask in a second etching process to define the cavity, and then removed to complete the MEMS structure.
Solution Approach 2:
The patent applies preliminary action by forming the metal ring structure before the cavity etching process. The metal ring is prepared in advance as an etching mask that defines the precise location and dimensions of the cavity. This preliminary formation of the metal ring ensures that when the cavity is etched, the alignment with the sensing membrane is maintained with high precision, avoiding alignment shifts that would occur without this pre-formed mask structure.
2Manufacturing precision
If the etching process window is narrowed to achieve precise alignment, then the manufacturing precision improves, but the productivity and product yield deteriorate due to increased sensitivity to process variations
Solution Approach 1:
The metal ring acts as an intermediary that decouples the alignment precision requirement from the etching process parameters. By using the metal ring as a physical mask, the alignment is determined by the metal ring's position and dimensions rather than by fine-tuning etching parameters. This intermediary structure provides a robust alignment mechanism that is insensitive to etching process variations, thereby maintaining high precision while allowing a broader process window and improving productivity and yield.
3Productivity
If alignment shifts occur during etching processes, then the manufacturing precision deteriorates, but increasing the etching process window to compensate reduces the manufacturing precision
Solution Approach 1:
The metal ring intermediary structure provides a stable reference that prevents alignment shifts during etching. The metal ring is formed with precise dimensions and position in a first etching process, and then serves as a mask in a second etching process. This two-step approach with the metal ring intermediary ensures that the cavity alignment is determined by the metal ring's pre-defined geometry rather than by alignment shifts during the etching process, thereby maintaining high precision while allowing a larger process window.
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
The method enables precise alignment of the cavity with the sensing membrane, enlarges the etching process window, and increases product yield by forming the metal ring with an expected pattern and arrangement, reducing alignment shifts and improving overall product quality.
Implementation Method 1
The metal ring serves as an etching mask to form a cavity aligned with the sensing membrane
Data Source
AI summary
A manufacturing method for a semiconductor structure is disclosed. The semiconductor structure includes a MEMS region. The MEMS region includes a sensing membrane and a metal ring. The metal ring defines a cavity under the sensing membrane.