Flashlamp Wafer Debonding Through a Light-Absorbing Carrier Layer
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Solution Overview
Problem
Existing methods for debonding silicon wafers from carriers in 3D integrated circuit manufacturing, such as chemical solvents, mechanical means, and laser-assisted techniques, are either damaging to the wafer surface or inefficient due to focal point variations and low throughput.
Innovation Solution
A method involving a light-absorbing layer on a carrier, combined with an adhesive layer, where a flashlamp pulse heats the adhesive to loosen the wafer, allowing for rapid and controlled debonding without surface damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical solvents are used to dissolve the adhesive, then the wafer can be debonded, but the wafer surface is damaged and harsh chemicals are required
Solution Approach 1:
The patent replaces chemical debonding methods with a mechanical/physical approach using a flashlamp to generate light that heats the adhesive layer. This substitution eliminates the need for harsh chemical solvents that damage wafer surfaces, using instead a controlled thermal field to degrade the adhesive and enable clean separation.
Solution Approach 2:
The patent changes the physical state and properties of the adhesive layer by applying rapid thermal energy from the flashlamp. The adhesive transitions from a bonded state to a degraded state through controlled heating, allowing debonding without chemical damage to the wafer surface.
2Reliability
If mechanical means are used to debond the wafer, then the adhesive can be removed, but the wafer surface is damaged through shearing or high temperature
Solution Approach 1:
The patent replaces mechanical shearing methods with an optical-thermal approach. Instead of applying mechanical force that causes surface damage, the flashlamp generates light that converts to heat in the adhesive layer, causing the adhesive to degrade and release the wafer without mechanical stress or high temperature contact.
Solution Approach 2:
The patent introduces light from the flashlamp as an intermediary medium to transfer energy to the adhesive layer. This intermediary enables indirect heating of the adhesive without direct mechanical or thermal contact with the wafer surface, preventing surface damage while achieving debonding.
3Reliability
If laser-assisted debonding is used, then the wafer can be debonded at room temperature, but the process has low throughput due to focal point variations and requires complex optics
Solution Approach 1:
The patent replaces expensive, complex laser optics with a simpler, more durable flashlamp system. The flashlamp provides sufficient light intensity for adhesive heating without requiring precise focal point control or complex optical components, thereby improving throughput and reducing system complexity.
Solution Approach 2:
The patent uses pulsed illumination from the flashlamp to deliver concentrated thermal energy to the adhesive layer. The periodic pulsed action allows for controlled heating and debonding without continuous energy input, improving efficiency and throughput while eliminating the need for complex continuous laser systems.
4Productivity
If a light-absorbing layer is added to the carrier, then rapid debonding is enabled, but the device complexity increases
Solution Approach 1:
The patent applies a light-absorbing layer only to the carrier substrate, creating a localized functional region. This layer selectively absorbs light energy and converts it to heat in the adhesive layer, enabling rapid debonding. The localized application maintains simplicity while achieving the desired functional improvement.
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
Enables rapid debonding of silicon wafers at room temperature with minimal stress, reducing processing time and complexity, and improving throughput by eliminating the need for rastering and complex optics.
Implementation Method 1
a light-absorbing layer is placed on a carrier. A wafer is then attached to the light-absorbing layer of the carrier via an adhesive layer
Implementation Method 2
a light pulse from a flashlamp is applied to a non-wafer side of the carrier to heat the light-absorbing layer and the adhesive layer
Data Source
AI summary
A method for debonding a wafer from a bonded wafer stack is disclosed. Initially, a light-absorbing layer is placed on a carrier. A wafer is then attached to the light-absorbing layer of the carrier via an adhesive layer to form a bonded wafer stack. After processing the wafer has been processed, a light pulse from a flashlamp is applied to a non-wafer side of the carrier to heat the light-absorbing layer and the adhesive layer in order to loosen the wafer from the bonded wafer stack. Finally, the wafer is removed from the bonded wafer stack.