MEMS Through-Hole Structure to Prevent Metal Layer Peeling
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Solution Overview
Problem
Existing MEMS devices face issues with peeling of metal layers from through-holes, which disrupt the controlled paths for charged particles, leading to poor control and efficiency.
Innovation Solution
The MEMS device design includes through-holes with lower portions wider than upper portions, ensuring that the metal layer does not extend to the sidewalls of the lower portions, thereby improving adhesion and reducing peeling, and using a conductive adhesion layer to enhance the bonding of the metal layer with underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the metal layer extends to the sidewalls of the lower portions of through-holes, then the coverage and continuity of the metal layer is improved, but the adhesion of the metal layer deteriorates causing peeling
Solution Approach 1:
The patent applies local quality by creating a wider lower portion in the through-holes where the metal layer is deposited. This local geometric modification ensures that the metal layer does not extend to the sidewalls in the lower portions, preventing peeling while maintaining continuity in the upper portions where full coverage is achieved.
2Ease of manufacture
If the through-holes have uniform width, then the manufacturing process is simplified, but the metal layer adhesion deteriorates causing peeling from deep portions
Solution Approach 1:
The through-holes are designed with non-uniform width, featuring wider lower portions and narrower upper portions. This local geometric variation is achieved through a two-step etching process that first creates initial through-holes and then selectively widens the lower portions, resolving the adhesion problem while maintaining manufacturing feasibility.
Solution Approach 2:
The patent employs preliminary action by first forming the through-holes with a standard etching process, then performing a second etching step to widen the lower portions before metal layer deposition. This preliminary geometric preparation ensures optimal metal layer adhesion from the beginning of the metallization process.
3Stability of the object's composition
If the metal layer is deposited conformally in deep through-holes, then the coverage is improved, but the metal layer peels from the deep portions disrupting charged particle paths
Solution Approach 1:
The patent applies local quality by modifying the through-hole geometry at the lower portions to be wider, which prevents the metal layer from extending to the sidewalls in these regions. This local geometric adjustment eliminates peeling while maintaining continuous metal layer coverage in the upper portions, ensuring uninterrupted charged particle paths.
Data Source
AI summary
A method includes forming an interconnect structure over a semiconductor substrate. The interconnect structure includes a plurality of dielectric layers, and the interconnect structure and the semiconductor substrate are in a wafer. A plurality of metal pads are formed over the interconnect structure. A plurality of through-holes are formed to penetrate through the wafer. The plurality of through-holes include top portions penetrating through the interconnect structure, and middle portions underlying and joining to the top portions. The middle portions are wider than respective ones of the top portions. A metal layer is formed to electrically connect to the plurality of metal pads. The metal layer extends into the top portions of the plurality of through-holes.