Wafer-Level Metallic Die Attach for Thin Power Semiconductor Handling
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Solution Overview
Problem
Current packaging and connection technologies limit the integration of thin power semiconductor devices into components and assemblies, constraining performance gains due to handling difficulties, potential damage, and limitations in heat and current capabilities.
Innovation Solution
A method involving attaching a metallic wafer to a thin semiconductor wafer at the wafer level, singulating both into separate bodies attached to individual semiconductor dies, and transferring them directly to assemblies, providing mechanical support and improved thermal and electrical benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If thin semiconductor dies (less than 250 microns) are used to enable smaller footprint and higher performance, then device performance and footprint are improved, but handling difficulty and damage risk increase
Solution Approach 1:
The patent attaches metallic bodies to the semiconductor wafer before singulation into individual dies. This preliminary attachment provides mechanical support to thin dies during subsequent handling and assembly operations, preventing damage while enabling the use of thinner, high-performance semiconductor substrates.
Solution Approach 2:
The metallic bodies serve as intermediary elements between the thin semiconductor die and the assembly substrate. These metallic bodies provide mechanical strength and structural support, acting as a mediator that protects the fragile thin die during handling while enabling reliable electrical and thermal connections in the final assembly.
2Ease of manufacture
If conventional packaging technologies are used for thin dies, then standard manufacturing processes are maintained, but manufacturing yields decrease due to die damage
Solution Approach 1:
The metallic bodies are attached to the semiconductor wafer before singulation, providing preliminary mechanical reinforcement. This allows standard packaging and assembly processes to be used while significantly reducing die damage during handling, thereby improving manufacturing yields without requiring entirely new manufacturing approaches.
3Productivity
If assembly connections are used to electrically couple power semiconductor devices to substrate, then device integration is achieved, but current capabilities are limited by connection technologies
Solution Approach 1:
The patent merges the electrical connection function with the mechanical support function by using metallic bodies that serve both purposes. These metallic bodies provide robust electrical connections capable of handling high currents while also providing mechanical support, eliminating the need for separate connection technologies and enabling higher current capabilities.
4Power
If assembly heat dissipation capabilities are used for high current applications, then power electronic devices can operate at high currents, but thermal limits of the assembly are exceeded
Solution Approach 1:
The metallic bodies serve as thermal intermediaries between the semiconductor die and the assembly substrate. These metallic bodies with high thermal conductivity provide efficient heat dissipation pathways, acting as thermal mediators that enable high current operation by effectively managing heat flow and preventing excessive temperature rise in the assembly.
Data Source
AI summary
A method includes providing a semiconductor wafer having a thickness of 250 microns or less. The semiconductor wafer includes a plurality of die sites each including a vertical power semiconductor device. The method further includes attaching a metallic wafer to the semiconductor wafer. The metallic wafer has a similar shape as the semiconductor wafer. Before or after attaching the metallic wafer to the semiconductor wafer, the die sites of the semiconductor wafer are singulated into individual semiconductor dies. After attaching the metallic wafer to the semiconductor wafer but before removing the individual semiconductor dies from the semiconductor wafer, the metallic wafer is singulated into a plurality of separate metallic bodies that remain attached to the individual semiconductor dies.