Spiked Via Electrode for Void-Free TSV Interconnects
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Solution Overview
Problem
The semiconductor industry faces challenges in creating reliable through-silicon vias (TSVs) due to voids formed during the filling process, which can lead to connection failures between semiconductor chips, especially as chip integration density increases and via hole diameters decrease, necessitating effective methods to prevent voids and ensure firm electrical connections.
Innovation Solution
The development of a via electrode design featuring a cylindrical body with tapered spikes extending into the substrate, which are filled with conductive material, along with a protrusion on the conductive pad, to enhance electrical connectivity and prevent voids, using a method that includes forming spike trenches and a via trench in the substrate and filling them with conductive materials, and planarizing the surface for improved interconnection patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If via hole diameters are decreased to increase integration density, then chip integration density is improved, but void formation in via holes increases leading to connection failures
Solution Approach 1:
The via electrode is segmented into multiple spikes instead of a single continuous structure. This segmentation allows the conductive material to be distributed through multiple separate pathways, reducing the likelihood of void formation and ensuring that if one spike has a void, other spikes can still provide electrical connection.
Solution Approach 2:
The via electrode structure transitions from uniform cylindrical shape to a non-uniform spike structure with varying diameters and lengths. Each spike can be optimized locally for its specific function, with wider bases providing structural support and narrower tips enabling penetration into the substrate, thereby improving both fillability and connection reliability.
2Ease of manufacture
If conventional TSV filling methods are used, then manufacturing process is simple, but voids are formed in the via electrode leading to connection failures
Solution Approach 1:
The spike structure is formed before filling with conductive material. The pre-formed spike geometry with varying cross-sections naturally guides the conductive material filling process, preventing void formation by ensuring proper material distribution and adhesion to the spike surfaces before the filling operation commences.
Solution Approach 2:
The spike structure acts as an intermediary between the via hole and the substrate. The spikes penetrate into the substrate and provide a gradual transition zone that facilitates complete filling with conductive material, preventing void formation by eliminating sharp corners and providing continuous surfaces for material adhesion.
3Manufacturing precision
If via holes are filled and substrate is stripped and polished, then TSV electrode is formed, but potential voids remain in the TSVs causing connection failures
Solution Approach 1:
The spike structures feature curved and tapered geometries rather than sharp corners or flat surfaces. This curvature ensures that conductive material can uniformly coat all surfaces and that voids cannot form in sharp corners. The rounded spike tips also facilitate complete filling by providing continuous contact surfaces.
Solution Approach 2:
The via electrode structure changes from a uniform cylindrical geometry to a variable geometry with spikes of different diameters and lengths. This parameter variation optimizes the filling process by creating pressure gradients and flow paths that prevent void formation, while also improving mechanical interlocking with the substrate.
Data Source
AI summary
A semiconductor device includes a semiconductor substrate and a via electrode. The via electrode has a first portion on the substrate and extends towards the substrate and has a plurality of spikes that extends from the first portion into the substrate, each of the spikes being spaced apart form one another.