Low-temperature flip chip die attach via solid-state diffusion
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Solution Overview
Problem
Traditional semiconductor device packaging methods using solder bumps or solder-tipped metal columns introduce excessive temperature-induced stresses, leading to delamination issues in semiconductor die interconnects, particularly with low-k and ultra-low-k dielectric materials due to differences in thermal expansion coefficients between the die and substrate materials.
Innovation Solution
A plug-and-socket or wedge-type mechanical connection system is formed using electroplating techniques, allowing for electrical coupling at room temperature with solid-state diffusion at lower temperatures, reducing stress on interconnects and using materials like copper and tin for strength and malleability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder reflow operation is used to electrically couple semiconductor die to package substrate, then electrical connection is achieved, but excessive temperature-induced stresses cause inter-layer dielectric delamination
Solution Approach 1:
The patent changes the temperature parameter from high (solder reflow) to low (solid-state diffusion bonding at lower temperature), achieving electrical connection while avoiding thermal stress delamination of low-k dielectric layers
Solution Approach 2:
The patent replaces the thermal-mechanical solder reflow process with a solid-state diffusion bonding process, eliminating the need for high-temperature melting and cooling cycles that cause thermal expansion mismatch and delamination
2Reliability
If traditional solder bumps are used for interconnect, then electrical coupling is established, but delamination occurs in low-k and ultra-low-k dielectric materials
Solution Approach 1:
The patent changes the bonding temperature parameter to enable solid-state diffusion at lower temperatures, preserving the integrity of low-k and ultra-low-k dielectric materials while establishing reliable electrical coupling
Solution Approach 2:
The patent employs a composite interconnect structure with a first material forming a plug and a second material forming a socket, enabling low-temperature solid-state diffusion bonding that protects sensitive dielectric layers
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 localized stresses at semiconductor device interconnects, preventing delamination and enabling reliable electrical connections while minimizing processing temperature, thus addressing the limitations of traditional solder-based methods.
Implementation Method 1
The plug and socket features can be diffusion bonded together to form the electrical interconnect
Implementation Method 2
The mechanical interconnect features can be formed on the die and substrate interconnects using an electroplating process
Data Source
AI summary
A mechanism for electrically coupling a semiconductor device die to a semiconductor device package substrate that avoids introduction of excessive temperature induced stresses to the semiconductor device die interconnect is provided. In one embodiment, the semiconductor device die is mechanically attached to the package substrate (or another semiconductor device die) at room temperature through the use of a plug-in socket or wedge connection having corresponding mating features formed on the die and substrate. The mechanical interconnect features can be formed on the die and substrate interconnects using an electroplating process. The surfaces of the semiconductor device die and package substrate can then be coupled using an underfill material. A low-temperature solid state bonding process can then be used to diffuse the materials forming the plug and socket features in order to form the electrical connection.