TSV Interconnects via Liquid Copper Filling for Stress Relief
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Solution Overview
Problem
Conventional through-silicon via (TSV) formation in 3D packaging experiences thermal expansion issues due to mismatched thermal coefficients of copper, silicon, and silicon oxide, leading to copper extrusion and defects in the interconnect structure, affecting yield and electrical properties.
Innovation Solution
A package structure and method involving a through-hole filled with an insulating layer, a diffusion barrier layer, and a metal interconnect layer, where the total thickness of these layers is less than the radius of the through-hole, reducing thermally induced stress and avoiding material extrusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperature is used during TSV formation, then copper filling and thermal processing are achieved, but thermal expansion mismatch causes copper extrusion from the through-hole
Solution Approach 1:
The patent changes the physical state parameter of copper from solid to liquid by controlling melting temperature. The copper is heated above its melting point to become liquid, allowing it to flow and fill the through-hole uniformly, then solidifies upon cooling to form a precise structure without extrusion
Solution Approach 2:
The patent utilizes the phase transition of copper between solid and liquid states. During processing, copper transitions from solid to liquid phase to enable complete filling of the through-hole, then transitions back to solid phase upon cooling, forming a precise interconnect structure without thermal expansion-induced extrusion
2Reliability
If the through-hole is completely filled with copper, then electrical connectivity is achieved, but thermal expansion has no space to accommodate causing extrusion
Solution Approach 1:
The patent changes copper from solid to liquid state during filling, allowing complete penetration into the through-hole. The liquid copper conforms to the entire volume including sidewalls and bottom, ensuring complete electrical connectivity. Upon cooling, it solidifies to form a stable structure
3Stress or pressure
If copper is extruded from the through-hole, then thermal expansion is accommodated, but the interconnect structure becomes non-flat causing device defects
Solution Approach 1:
By maintaining copper in liquid state during filling and controlling the cooling process, the patent ensures uniform distribution throughout the through-hole. The liquid copper can accommodate thermal movement more uniformly, and upon solidification, forms a flat surface that maintains both stress relief and surface flatness
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 reduces thermal stress and maintains process stability and electrical properties by preventing copper extrusion and ensuring a flat surface for interconnect formation.
Implementation Method 1
melting the metal to form liquid metal; pouring the liquid metal into the through-hole
Implementation Method 2
allowing the liquid metal to solidify within the through-hole
Implementation Method 3
forming an insulating layer coating on a sidewall of the through-hole
Data Source
AI summary
Various embodiments provide semiconductor devices including a package structure and methods of forming the semiconductor devices. In one embodiment, the package structure can include a through-hole at least partially filled by one or more layers of material(s) to form a through-hole interconnect between semiconductor devices in the package structure. The through-hole can be filled by an insulating layer, a diffusion barrier layer, a metal interconnect layer, and/or a protective layer having a total thickness from the sidewall of the through-hole of less than or equal to the radius of the through-hole.