Novolac Resin Peeling Layer for Laser-Assisted Wafer Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional temporary adhesives for semiconductor wafers generate heat and gas when irradiated with laser light, causing damage during the adhesion and separation processes, particularly during the polishing of the back surface, which can lead to deformation or cutting of the wafer.
Innovation Solution
A laminated body with an intermediate layer containing a novolac resin that absorbs ultraviolet light, allowing for photodecomposition and stress-free separation of the wafer from the support without mechanical load, using a peeling layer that absorbs light in the 190 nm to 600 nm wavelength range and includes a hydrosilylation reaction-cured adhesion layer and polydimethylsiloxane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional temporary adhesive is used for wafer adhesion and separation, then the wafer can be held on the support during polishing, but heat and gas are generated when irradiated with laser light, causing damage to the wafer
Solution Approach 1:
The patent changes the chemical composition parameters of the temporary adhesive by incorporating specific compounds: a phenolic resin (novolac type) as the base polymer, a boron-containing compound as crosslinking agent, and a silane compound. This chemical parameter modification enables the adhesive to undergo photodecomposition at lower temperatures without generating harmful gas, thus resolving the contradiction between maintaining wafer integrity and avoiding heat/gas damage during laser irradiation
Solution Approach 2:
The patent replaces the conventional thermal decomposition mechanism with a photodecomposition mechanism. By incorporating a boron-containing compound that absorbs laser light and facilitates photochemical bond breaking, the adhesive separates through light-induced chemical reactions rather than thermal degradation. This substitution eliminates heat generation and gas evolution during separation, directly addressing the harmful effects while maintaining reliable wafer holding during polishing
2Ease of operation
If a large force is applied for wafer detachment from the support, then the wafer can be separated from the adhesive, but the thinned semiconductor wafer may be cut or deformed
Solution Approach 1:
The patent applies preliminary action by incorporating a silane compound into the adhesive formulation that, when exposed to laser light, undergoes rapid photodecomposition to generate silicon dioxide. This pre-planned chemical reaction creates a controlled separation interface that reduces adhesion strength before mechanical detachment is attempted, allowing easy peeling without applying large forces that could cut or deform the thinned wafer
Solution Approach 2:
The silicon dioxide generated through photodecomposition of the silane compound acts as an intermediary substance between the adhesive and the wafer. This intermediary layer facilitates smooth separation by providing a low-friction interface during peeling, enabling easy detachment while preventing direct mechanical stress concentration on the wafer that would cause cutting or deformation
3Strength
If the adhesion force is increased for high stress in polishing, then the wafer remains stable during polishing, but the adhesion force becomes too strong for easy detachment
Solution Approach 1:
The patent applies dynamics by creating a time-dependent and condition-dependent adhesion system. During polishing, the adhesive maintains strong adhesion force through the crosslinked phenolic resin-boron compound network. Upon laser irradiation, the boron-containing compound undergoes photodecomposition, dynamically reducing the adhesion force. This dynamic behavior allows the same adhesive to provide both strong holding during polishing and easy detachment during separation, resolving the contradiction between these opposing requirements
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 stress-free separation of semiconductor wafers from the support during polishing, preventing deformation and damage, while allowing for easy removal of the adhesion layer using a tape, thus maintaining the integrity of the wafer.
Implementation Method 1
the peeling layer contains a novolac resin that absorbs light with a wavelength of 190 nm to 600 nm incident through the support, resulting in modification
Implementation Method 2
a material and a method for separation without mechanical load... resulting in photodecomposition
Data Source
AI summary
A laminated body for polishing a back surface of a wafer, the laminated body including an intermediate layer that is disposed between a support and a circuit surface of the wafer and peelably adheres to the support and the circuit surface, wherein the intermediate layer includes an adhesion layer in contact with the wafer and a peeling layer in contact with the support, and the peeling layer contains a novolac resin that absorbs light with a wavelength of 190 nm to 600 nm incident through the support, resulting in modification. The light transmittance of the peeling layer at a wavelength range of 190 nm to 600 nm may be 1 to 90%. The modification caused by absorption of light may be photodecomposition of the novolac resin.