Solderless Copper Interconnect Assembly Without IMC Interfaces
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Solution Overview
Problem
Direct chip attach methods in semiconductor packages often result in the formation of intermetallic compounds (IMCs) that degrade electrical characteristics and cause reliability issues due to thermal stresses, leading to increased resistance and brittleness, which can lead to catastrophic failures and warpages in the semiconductor device assembly.
Innovation Solution
The use of a low thermal-budget electroless plating process to form solderless interconnects, eliminating IMCs and associated interfaces, thereby improving electrical and metallurgical characteristics and reducing thermal-related reliability issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If direct chip attach methods are used to reduce footprints, then the footprint of the semiconductor package is reduced, but intermetallic compounds form at the interfaces causing increased resistance and reliability issues
Solution Approach 1:
The patent removes the solder material from the bonding interface, eliminating the formation of intermetallic compounds that cause reliability issues. The direct metal-to-metal contact between the semiconductor die and substrate is achieved without intermediate solder layers, thereby extracting the harmful IMC formation mechanism from the system.
Solution Approach 2:
The patent changes the bonding parameters by using low-temperature bonding processes instead of high-temperature soldering. This parameter change prevents the formation of intermetallic compounds while still achieving reliable electrical and mechanical bonding, thus improving electrical characteristics without increasing footprint.
2Strength
If annealing steps are used to facilitate bonding between different metallic materials, then bonding is facilitated, but thermal stresses cause cracks and warpages leading to high resistance
Solution Approach 1:
The patent changes the temperature parameter by using low-temperature bonding processes that eliminate the need for high-temperature annealing steps. This prevents thermal stress accumulation that would otherwise cause cracks and warpages, while still achieving adequate bonding strength through alternative mechanisms such as eutectic bonding or direct metal bonding at reduced temperatures.
Solution Approach 2:
The patent replaces the thermal bonding mechanism (annealing) with alternative bonding mechanisms that do not rely on high temperatures. This substitution eliminates the thermal stress cycle that causes structural degradation, while maintaining bonding strength through different physical or chemical mechanisms.
3Reliability
If solderless interconnects are used to eliminate IMCs, then electrical characteristics improve, but new bonding methods must be developed
Solution Approach 1:
The patent employs self-aligning and self-bonding mechanisms where the metallic surfaces automatically align and bond through atomic diffusion or eutectic reactions at the interface. This self-service mechanism eliminates the need for complex alignment and bonding equipment, making the solderless interconnect process as manufacturable as traditional soldering while achieving superior electrical characteristics.
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 solderless interconnects provide improved electrical characteristics and reduced thermal stress, enhancing the reliability and performance of semiconductor device assemblies by eliminating IMCs and associated interfaces, thus preventing failures and warpages.
Implementation Method 1
a third metal structure conjoining the first metal structure and the second metal structure, where the third metal structure is formed with an electroless plating solution injected between the first metal structure and the second metal structure
Data Source
AI summary
Semiconductor device assemblies with solderless interconnects, and associated systems and methods are disclosed. In one embodiment, a semiconductor device assembly includes a first conductive pillar extending from a semiconductor die and a second conductive pillar extending from a substrate. The first conductive pillar may be connected to the second conductive pillar via an intermediary conductive structure formed between the first and second conductive pillars using an electroless plating solution injected therebetween. The first and second conductive pillars and the intermediary conductive structure may include copper as a common primary component, exclusive of an intermetallic compound (IMC) of a soldering process. A first sidewall surface of the first conductive pillar may be misaligned with respect to a corresponding second sidewall surface of the second conductive pillar. Such interconnects formed without IMC may improve electrical and metallurgical characteristics of the interconnects for the semiconductor device assemblies.