MEMS Wire Recess Width Variation for Dishing Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In MEMS devices with embedded wires on silicon substrates, the phenomenon of dishing occurs during polishing, leading to uneven wire heights and increased risk of disconnections and resistance due to the softer conductive materials being easily removed, resulting in reliability issues.
Innovation Solution
A configuration where the recess openings in the connection region are narrower than outside regions, with a support portion and a resilient bump electrode to ensure reliable electrical connection and reduce load during connection, and the recesses are formed using anisotropic etching to increase the cross-sectional area of the wires while minimizing the opening width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If embedded wires are formed on a silicon substrate and excess portions are polished away, then the wires can be made even with the substrate surface, but dishing occurs in which the conductive portions sink below the substrate surface
Solution Approach 1:
The patent applies local quality by making the recess opening width variable along the wire length. Specifically, the opening width is narrower at the connection regions (where bump electrodes connect) and wider in the middle portions. This localized variation in geometry allows the connection regions to resist dishing during polishing while maintaining overall wire height uniformity, thereby resolving the contradiction between manufacturing precision and reliability.
2Manufacturing precision
If the opening width of recesses is reduced to suppress dishing, then wire height uniformity improves, but the cross-sectional area of wires decreases
Solution Approach 1:
The patent implements local quality by creating a non-uniform opening width profile where connection regions have narrower openings (to suppress dishing) while middle portions have wider openings (to maintain cross-sectional area). This localized differentiation allows the system to achieve both small opening widths for dishing suppression and sufficient wire cross-sectional area for electrical performance.
Solution Approach 2:
The patent segments the recess structure into different regions along the wire length: connection regions with narrower openings and middle portions with wider openings. This segmentation allows each region to be optimized for its specific function - connection regions for dishing suppression and middle portions for maintaining electrical conductivity - thereby resolving the contradiction between opening width and cross-sectional area.
3Manufacturing precision
If the opening width of recesses is reduced to suppress dishing, then wire height uniformity improves, but electrical resistance increases
Solution Approach 1:
The patent applies local quality by concentrating the narrow opening width specifically at connection regions where dishing suppression is most critical, while maintaining wider openings in middle portions that contribute more to electrical conductivity. This localized approach minimizes the impact on overall electrical resistance while achieving the desired suppression of dishing.
Solution Approach 2:
The patent segments the recess into connection regions and middle portions with different opening widths. The middle portions with wider openings serve as the primary current-carrying paths, maintaining low electrical resistance, while the connection regions with narrower openings focus on mechanical stability and dishing suppression. This segmentation resolves the contradiction between opening width and electrical conductivity.
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 configuration effectively suppresses dishing, reduces the risk of disconnections and increased resistance, and enhances the reliability of electrical connections in MEMS devices by maintaining even wire heights and reducing the load required for connection.
Implementation Method 1
the recesses are formed using anisotropic etching to increase the cross-sectional area of the wires while minimizing the opening width
Data Source
AI summary
A MEMS device includes a wire that is formed of a conductive portion embedded into a recess opened in a first face of a substrate and a bump electrode that is electrically connected to the wire. A total width, in a second direction intersecting a first direction along which the wire extends on the first face, of an opening of the recess in a connection region where the wire and the bump electrode are electrically connected to each other is narrower than a width, in the second direction, of an opening of the recess in a region outside the connection region.