Silicide Layer on Redistribution Line for TSV Bonding
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Solution Overview
Problem
Conventional through-silicon via (TSV) bonding techniques face limitations due to the need for large pitch between TSVs, leading to restricted location and potential joint failure from adjacent solder balls touching, necessitating new backside structures for improved reliability and bondability.
Innovation Solution
A novel backside connection structure featuring a through-silicon via (TSV) with a redistribution line (RDL) and a silicide layer on the backside of the semiconductor substrate, where the RDL includes copper and is covered by a passivation layer with an opening for a metal finish, reducing oxidation and enhancing bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional TSV bonding techniques are used, then TSVs can connect integrated circuits on a die to the backside of the die, but large pitch between TSVs is required which restricts TSV locations and may cause joint failure from adjacent solder balls touching
Solution Approach 1:
The patent introduces redistribution lines (RDLs) that extend TSV connections laterally across the backside of the substrate, transforming the connection architecture from direct vertical bonding to a distributed network. This dimensional expansion allows multiple TSVs to share bonding locations while maintaining electrical connectivity through the RDL network, effectively reducing the required pitch between TSVs and enabling denser integration without increasing bonding complexity
Solution Approach 2:
The patent introduces a silicide layer as an intermediary between the copper TSV and the solder ball, and also uses RDLs as intermediaries to distribute connections. The silicide layer prevents direct oxidation of copper while maintaining electrical conductivity, enabling reliable bonding at smaller pitches where oxidation would otherwise cause joint failure. This intermediary layer resolves the contradiction by protecting the TSV structure without requiring larger pitch
2Reliability
If copper is used for TSV and RDL, then electrical conductivity is improved, but oxidation of the copper reduces bondability and joint integrity
Solution Approach 1:
The patent introduces a silicide layer as an intermediary between the copper TSV/RDL and the external environment (solder, oxidation). This silicide layer acts as a protective barrier that prevents copper oxidation while maintaining electrical conductivity, thereby preserving both the low resistance path of copper and the bondability required for reliable joints. The intermediary layer resolves the contradiction by decoupling the electrical function from the protective function
Solution Approach 2:
The patent creates a composite structure consisting of copper TSV/RDL combined with a silicide layer coating. This composite material system combines the high electrical conductivity of copper with the oxidation resistance of silicide, achieving both low resistance and high reliability simultaneously. The composite structure resolves the contradiction by integrating the beneficial properties of both materials in a single functional unit
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
The solution improves bondability and reliability by reducing RDL oxidation, resulting in enhanced joint integrity and performance in stacked die structures.
Implementation Method 1
A silicide layer is over and contacting the RDL... The solution improves bondability and reliability by reducing RDL oxidation
Data Source
AI summary
An integrated circuit structure includes a semiconductor substrate having a front side and a backside. A through-silicon via (TSV) penetrates the semiconductor substrate. The TSV has a back end extending to the backside of the semiconductor substrate. A redistribution line (RDL) is over the backside of the semiconductor substrate and connected to the back end of the TSV. A silicide layer is over and contacting the RDL.