Wafer Debonding via Infrared Ablation of Metallic Bonding Layers
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Solution Overview
Problem
Thinned silicon wafers are fragile and prone to defects during processing, making handling challenging, and existing UV laser ablation methods are incompatible with silicon handlers due to poor thermal conductivity and high costs.
Innovation Solution
A bonding structure comprising an adhesive layer and a thin metallic layer that absorbs infrared radiation for efficient debonding by infrared radiation ablation, allowing for the use of silicon handlers compatible with standard CMOS processing technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV laser ablation is used to debond wafers, then debonding can be achieved, but silicon handlers are incompatible due to poor thermal conductivity and high cost
Solution Approach 1:
The patent changes the laser wavelength parameter from UV to infrared, which fundamentally alters the interaction with silicon material. Silicon is transparent to infrared radiation, allowing the laser to pass through the handler and ablate the adhesive layer without heating the silicon substrate, thus enabling compatibility with silicon handlers
Solution Approach 2:
The patent introduces an infrared-absorbing layer as an intermediary component in the bonding structure. This layer absorbs the infrared laser energy and converts it to heat, which then transfers to the adhesive layer for debonding, while the silicon handler remains unaffected due to its infrared transparency
2Productivity
If thinned silicon wafers are handled, then large-scale integration and high density packaging are achieved, but mechanical strength is reduced making handling challenging
Solution Approach 1:
The patent applies preliminary action by bonding thinned wafers to handler wafers before processing. The handler wafer provides mechanical support and protection during handling and processing steps, preventing damage to the fragile thinned wafer until the bonding is removed after processing
3Strength
If handler wafers are attached to device wafers to enhance mechanical integrity, then handling is facilitated, but debonding requires complex techniques such as thermal release or chemical dissolving
Solution Approach 1:
The patent replaces complex thermal or chemical debonding processes with a simplified laser ablation process. By using infrared laser to directly ablate the adhesive layer, the debonding operation becomes a precise, controlled, and simpler process compared to thermal release or chemical dissolving methods
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 method enables efficient and cost-effective debonding of thinned silicon wafers from handler wafers using infrared radiation, enhancing mechanical integrity during processing and reducing defects, while being compatible with standard semiconductor technologies.
Implementation Method 1
The metallic layer serves as a releasable layer of the bonding structure by infrared ablation of the metallic layer
Implementation Method 2
irradiating the bonding structure with long-wavelength infrared energy to ablate the bonding structure
Implementation Method 3
The bonding structure comprises an adhesive layer having infrared energy absorbing nanoparticles
Implementation Method 4
The adhesive layer serves as a releasable layer by infrared ablation of the adhesive layer
Data Source
AI summary
Methods are provided for handling a device wafer. For example, a method includes providing a stack structure having a device wafer, a handler wafer, and a bonding structure disposed between the device wafer and handler wafer, and irradiating the bonding structure with long-wavelength infrared energy to ablate the bonding structure.