Post Passivation Interconnect Structure for TSV Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional post passivation interconnect structures in through-silicon via fabrication exhibit weak adhesion to contact-bonding pads, leading to high contact resistance, which hinders the advancement of three-dimensional integrated circuit density and efficiency.
Innovation Solution
A novel post passivation interconnect structure is developed, where a conductive material is deposited to form a metal ring or pillars surrounding the contact-bonding pad, providing enhanced adhesion and reducing contact resistance by creating a conductive plug that connects the pad to the underlying metal line, using techniques such as reactive ion etching and copper plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional post passivation interconnect structure is used, then the fabrication process is simple, but the adhesion to contact-bonding pad is weak and contact resistance is high
Solution Approach 1:
The patent employs a composite interconnect structure consisting of multiple material layers including tungsten, copper, and dielectric materials. The PPI structure integrates a conductive plug (tungsten), a barrier layer, and a copper seed layer to achieve both strong adhesion to the contact-bonding pad and low contact resistance, while maintaining compatibility with existing fabrication processes
Solution Approach 2:
The patent implements a nested structure where the conductive plug is embedded within the dielectric layer, and the PPI structure is formed around and connected to the contact-bonding pad. This nested arrangement allows the interconnect structure to provide both mechanical support and electrical connection while minimizing disruption to the surrounding circuitry
2Quantity of substance
If integration density is increased through 3DIC and stacked dies, then more components are integrated, but contact resistance increases and adhesion becomes weaker
Solution Approach 1:
The patent applies local quality by creating a specialized PPI structure with enhanced adhesion properties specifically at the contact-bonding pad interface. The conductive plug and barrier layer are locally configured to provide optimal electrical and mechanical properties where needed, while the rest of the interconnect structure maintains standard design for signal transmission
Solution Approach 2:
The patent introduces an intermediary barrier layer between the conductive plug and the contact-bonding pad that serves as a mediator to reduce contact resistance. This intermediate layer facilitates better electrical contact and adhesion between the dissimilar materials, enabling reliable connections in high-density 3DIC configurations
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 improved structure achieves better adhesion and lower contact resistance, enabling increased integration density and reduced power consumption in three-dimensional integrated circuits by effectively connecting stacked dies through-silicon vias.
Implementation Method 1
using techniques such as reactive ion etching and copper plating
Implementation Method 2
using techniques such as reactive ion etching and copper plating
Data Source
AI summary
An integrated circuit structure includes a semiconductor substrate, a through-silicon via (TSV) extending into the semiconductor substrate, a pad formed over the semiconductor substrate and spaced apart from the TSV, and an interconnect structure formed over the semiconductor substrate and electrically connecting the TSV and the pad. The interconnect structure includes an upper portion formed on the pad and a lower portion adjacent to the pad, and the upper portion extends to electrically connect the TSV.