Power Die Spacer Stack for Thin-Wafer Strength and Warpage Control
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Solution Overview
Problem
High-power semiconductor devices with large-size, thin die configurations are prone to mechanical and thermal stresses, leading to issues like warpage, chipping, and breaking during packaging and assembly due to their fragile nature.
Innovation Solution
The method involves bonding a conductive spacer block to the device die to create a reinforced vertical device stack, which is then processed and handled as a single unit, reducing the risk of damage by increasing the mechanical strength and thickness of the die, thereby preventing warpage and chipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large-size, thin device die are used to meet high power requirements, then power delivery capability is improved, but mechanical strength deteriorates leading to warpage and chipping
Solution Approach 1:
The device structure is segmented into multiple functional layers: the thin device die for power delivery, a bonding layer for mechanical support, and a thick conductive spacer block for enhanced mechanical strength. This segmentation allows each layer to perform its specialized function while collectively solving the strength problem of thin die
Solution Approach 2:
The invention uses composite material structures by bonding the device die to a conductive spacer block through a bonding layer. This composite structure combines the electrical properties of the semiconductor die with the mechanical properties of the conductive spacer block, achieving both high power capability and mechanical strength
2Length of moving object
If thin device die are used to reduce size, then device dimensions are improved, but reliability deteriorates due to susceptibility to damage during packaging and assembly
Solution Approach 1:
The conductive spacer block is bonded to the device die beforehand to provide mechanical support and cushioning. This pre-reinforcement protects the thin die from damage during subsequent packaging and assembly operations, allowing the die to be thin while maintaining reliability
Solution Approach 2:
The bonding layer acts as an intermediary between the thin device die and the thick conductive spacer block. This intermediate layer provides a transition zone that bonds the two components while accommodating differences in their mechanical properties, ensuring reliable attachment without damaging the thin die
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 allows for the successful assembly of large-size, thin device dies into circuit packages without the traditional issues of warpage, chipping, or breaking, while maintaining desirable joint quality between die and conductive materials.
Implementation Method 1
reflowing the solder material layer or sintering the sintering material to bond the device die and the conductive spacer block
Implementation Method 2
reflowing the solder material layer or sintering the sintering material to bond the device die and the conductive spacer block
Implementation Method 3
activating the coupling mechanism material to bond the conductive spacer blocks to the backside of the selected wafer
Data Source
AI summary
A method includes placing a coupling mechanism material layer on a backside of a wafer having power devices fabricated on a frontside thereof, and placing conductive spacer blocks on the coupling mechanism material layer on a backside of the selected wafer. The method further includes activating the coupling mechanism material to bond the conductive spacer blocks to the backside of the selected wafer, and singulating the wafer to separate the vertical device stacks, each of the singulated vertical device stacks including a device die bonded to, or fused with, a conductive spacer block.