Temporary Wafer Debonding Using Flashlamp-Heated Adhesive Layers
Find Innovative SolutionsGenerate Solutions
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 harmful to the wafer surface or inefficient due to focal point variations, power fluctuations, and low throughput.
Innovation Solution
A method involving a light-absorbing layer on a carrier, combined with a flashlamp to heat the adhesive layer, allowing the wafer to be debonded at room temperature with minimal stress using a single intense light pulse, reducing the need for complex scanning optics and increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If chemical solvents are used to debond the wafer from the carrier, then the adhesive is dissolved and the wafer can be separated, but the chemical solvents are harmful to the wafer surface and require additional cleaning steps
Solution Approach 1:
The patent replaces chemical debonding with a photothermal mechanism. A light-absorbing layer is deposited on the carrier, and when illuminated by a light source (such as a laser or flashlamp), it converts optical energy to thermal energy, heating the adhesive layer to a temperature where it loses adhesion strength, enabling mechanical separation without chemical damage to the wafer surface.
Solution Approach 2:
The light-absorbing layer acts as an intermediary between the light source and the adhesive layer. It absorbs the optical energy and converts it to heat, which is then transferred to the adhesive layer, causing the adhesive to soften and release the wafer without direct contact between the light source and the wafer, protecting the wafer from direct thermal or optical damage.
2Manufacturing precision
If laser-assisted debonding is used, then the adhesive layer is heated and the wafer can be debonded, but focal point variations and power fluctuations cause inconsistencies and low throughput
Solution Approach 1:
The patent employs periodic pulsed illumination rather than continuous laser exposure. The light source emits intense light pulses for short durations (e.g., microseconds to milliseconds), heating the adhesive layer rapidly and uniformly during each pulse. This periodic action allows for consistent debonding across multiple wafers while maintaining high throughput, as the system can quickly cycle through multiple wafers without the focal point or power stability issues of continuous laser systems.
3Manufacturing precision
If a light-absorbing layer is used with flashlamp illumination, then the adhesive layer is heated uniformly and the wafer debonds cleanly at room temperature, but additional layer deposition is required
Solution Approach 1:
The light-absorbing layer is a consumable component that is discarded after use. Each wafer carrier is prepared with a light-absorbing layer that enables a single debonding operation. After the wafer is removed, the carrier with the depleted light-absorbing layer is discarded or recycled for re-coating, rather than attempting to recover or reuse the degraded light-absorbing material. This approach simplifies the overall process by eliminating the need for complex recovery systems.
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 achieves rapid and clean debonding of silicon wafers with reduced energy consumption and minimal damage, improving throughput and consistency compared to existing methods.
Implementation Method 1
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
Implementation Method 2
heat the light-absorbing layer and the adhesive layer in order to loosen the wafer from the bonded wafer stack
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.