TSV Segmentation for Stress Redistribution
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Solution Overview
Problem
Through substrate vias (TSVs) in semiconductor processing face stress issues due to conductive material shrinkage, which limits the maximum length and causes structural integrity problems when filled with conductive materials like tungsten.
Innovation Solution
Incorporating features with maximum widths at the ends of the TSV, which are at least twice the minimum width, to redistribute stress and extend the TSV length, allowing for longer structures while reducing stress at the longitudinal ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TSV is filled with conductive material, then electrical connections are established, but stress causes pulling on the walls limiting maximum length
Solution Approach 1:
The TSV opening is divided into multiple sections by adding intermediate features (such as mandrels or support structures) along the length of the via. These features segment the continuous conductive fill into sections, reducing the stress span and preventing wall pulling while maintaining electrical connectivity throughout the extended structure
Solution Approach 2:
Different regions of the TSV are given different properties - the intermediate features have higher structural strength and smaller cross-sectional area compared to the main conductive regions. This local variation in quality allows stress redistribution, with the intermediate features acting as stress relief points that prevent wall pulling while maintaining overall electrical conductivity
2Length of stationary object
If TSV length is extended, then more backside connections are enabled, but stress at longitudinal ends increases causing structural problems
Solution Approach 1:
The long TSV structure is segmented by introducing intermediate features at regular intervals along its length. These features break up the continuous stress path, preventing stress accumulation at the longitudinal ends while maintaining the extended length necessary for multiple backside connections
Solution Approach 2:
Intermediate features act as mediators between the conductive material and the TSV walls. These features have smaller cross-sectional areas that reduce direct stress transmission to the walls, while still providing structural support and maintaining the integrity of the extended TSV structure
Data Source
AI summary
A structure having a substrate includes an opening in the substrate having depth from a top surface of the substrate to a bottom surface of the substrate. A conductive material fills the opening. The opening has a length direction and a width direction and a first and second feature. The first feature and the second feature are spaced apart by a first length. The first feature has first width as a maximum width of the first feature, and the second feature has a second width as the maximum width of the second feature. The opening has a minimum width between the first feature and the second feature that is no more than one fifth the first length. The first width and the second width are each at least twice the minimum width.