Gold Through-Silicon Mask Plating to Prevent Via Close-Off Voids
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Solution Overview
Problem
Gold through silicon mask (TSM) plating faces challenges with spurious gold deposition on silicon masks, especially at via openings, leading to incomplete via filling and the formation of voids due to premature closure of via entrances.
Innovation Solution
The implementation of a cyclical deposition-etch treatment process, known as Etch Assisted Gold Through Silicon Mask (EAG-TSM), which includes alternating sub-steps of gold plating and etch treatment to minimize silicon field plating and maintain via entrance integrity, thereby ensuring complete via fill and eliminating close-off voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional TSM plating is used to fill vias with gold, then via filling is achieved, but spurious gold deposition occurs on silicon masks especially at via openings leading to premature closure and void formation
Solution Approach 1:
The patent applies periodic action by implementing a cyclical plating-etch process where gold plating and etching steps are alternated in repeated cycles. This periodic treatment allows controlled deposition of gold in via regions while removing spurious deposits from silicon mask areas, preventing via entrance closure and achieving uniform via filling without void formation.
Solution Approach 2:
The patent applies the extraction principle by selectively removing spurious gold deposits from silicon mask surfaces using etching steps while preserving the gold plating in via regions. This selective extraction eliminates harmful deposits that would otherwise cause via entrance closure, while maintaining the desired via fill structure.
2Quantity of substance
If extended plating time is used to ensure complete via fill, then via filling is improved, but spurious deposition on silicon fields increases and via entrances close off
Solution Approach 1:
The cyclical plating-etch process uses periodic action to alternate between gold deposition and selective removal. During plating cycles, gold is deposited in via regions; during subsequent etching cycles, spurious deposits on silicon masks are removed. This periodic alternation enables extended total plating time to achieve complete via fill while preventing via entrance closure by periodically clearing spurious deposits.
Solution Approach 2:
The patent applies continuity of useful action by maintaining the plating process over extended periods through repeated cycles, ensuring complete via filling is achieved. The continuous alternation between plating and etching maintains via entrance integrity throughout the extended process duration, preventing premature closure while achieving thorough via fill.
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 effectively minimizes spurious gold deposition on silicon fields, maintains the integrity of via entrances, and achieves complete and uniform via filling, even in high aspect ratio structures, thereby reducing the occurrence of voids and improving overall plating efficiency.
Implementation Method 1
subjecting the masked substrate to at least one processing cycle, each processing cycle including an Au plating sub-step
Implementation Method 2
residual Au deposited adjacent a via by the plating sub-step is removed by the etch treatment sub-step
Data Source
AI summary
Systems and methods are provided for method for etch assisted gold (Au) through silicon mask plating (EAG-TSM). An example method comprises providing a seed layer on a substrate and providing a silicon mask on at least a portion of the seed layer on the substrate. The silicon mask includes one or more via to be filled with Au. The masked substrate is subjected to at least one processing cycle, each processing cycle including an Au plating sub-step and an etch treatment sub-step. The cycles are repeated until a selected via fill thickness is achieved.