3D Die Stacking Microbump Joints Without UBM Pads
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Solution Overview
Problem
Existing semiconductor packaging technologies face challenges in achieving cost-effective, high-performance 3D die stacking with fine-pitch microbumps that address thermal expansion mismatch and provide reliable electrical connections.
Innovation Solution
A semiconductor package structure that includes a Die-to-Die (D2D) interconnection structure with a System on Chip (SoC) package bonded to an Integrated Fan-Out (InFO) package, utilizing a 3D stacking design without under-ball metallurgy (UBM) pads in certain regions, featuring a cost-effective, fine-pitch microbump structure with high strength and rigidity, and incorporating intermetallic compounds for improved electromigration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional semiconductor packaging with UBM pads is used, then reliable electrical connections are achieved, but manufacturing cost increases and device complexity increases
Solution Approach 1:
The patent removes the UBM pad layer from the microbump structure, extracting only the essential copper interconnect and solder microbump components. This simplification eliminates unnecessary manufacturing steps and material layers while maintaining electrical connection reliability through direct copper-to-solder bonding.
Solution Approach 2:
The copper interconnect structure serves multiple functions: it provides electrical connection, thermal management, and structural support for the microbump. This multi-functionality eliminates the need for separate UBM pads that traditionally handled only electrical connection, reducing overall device complexity and manufacturing cost.
2Reliability
If fine-pitch microbumps are implemented for high-density interconnection, then electrical connectivity is improved, but manufacturing precision requirements increase and device complexity increases
Solution Approach 1:
The patent changes the material composition parameters of the microbump structure, using copper-rich intermetallic compounds that provide superior mechanical properties and bonding characteristics. This material parameter change enables finer pitch dimensions while maintaining manufacturing feasibility and connection reliability.
Solution Approach 2:
The microbump structure uses composite materials combining copper interconnect with solder alloy, creating a material system that offers both fine-pitch compatibility and robust electrical connection. The composite structure provides the necessary mechanical strength and electrical conductivity for high-density interconnection without excessive manufacturing precision requirements.
3Reliability
If copper-rich intermetallic compounds are used in joint parts, then electromigration resistance is improved and manufacturing cost is reduced, but manufacturing process complexity increases
Solution Approach 1:
The patent adjusts the chemical composition parameters of the joint part material to achieve copper-rich intermetallic compounds. This parameter change enhances electromigration resistance by creating a more stable metallurgical structure that resists copper atom migration under electrical stress, while the process remains compatible with existing semiconductor manufacturing capabilities.
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 provides a reliable and cost-effective 3D stacking solution with enhanced electrical connectivity and thermal management, suitable for high-performance applications such as CPUs, GPUs, and FPGAs, by using copper-rich intermetallic compounds for improved reliability and reduced manufacturing costs.
Implementation Method 1
the joint parts include an intermetallic compound
Data Source
AI summary
A semiconductor package structure includes a first die having a first bonding surface, a second die having a second bonding surface in which the second bonding surface faces the first bonding surface, and an intermediate structure between the first bonding surface and the second bonding surface. The intermediate structure includes a plurality of traces over the first bonding surface, a plurality of microbumps over the second bonding surface, and a plurality of joint parts between the traces and the microbumps, wherein the joint parts include an intermetallic compound.