Polyimide Release Layer for Rapid Laser Debonding
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Solution Overview
Problem
Existing laser release materials for temporary wafer bonding require long curing times, significantly decreasing the throughput of the process.
Innovation Solution
A UV release layer comprising a polymer with recurring monomers such as fluorinated dianhydrides, photosensitive dianhydrides, and photosensitive diamines is used, which can be formed in less than 10 minutes at temperatures between 250°C to 350°C, allowing for rapid formation and subsequent laser-induced separation of substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional laser release materials are used, then the release layer can be formed with sufficient thickness, but the curing time becomes extremely long (one hour or more at high temperature)
Solution Approach 1:
The patent changes the chemical composition parameters of the release layer by incorporating photosensitive monomers (curing agents) that enable UV-induced polymerization. This allows the film to be formed at lower temperatures (e.g., 80-120°C) for much shorter times (minutes rather than hours), dramatically reducing curing time while maintaining adequate film quality for laser release functionality
Solution Approach 2:
The patent applies a preliminary UV curing step after depositing the release layer to activate the photosensitive monomers before laser processing. This preliminary action creates a crosslinked polymer network that provides sufficient structural integrity and adhesion, enabling the subsequent laser release to proceed effectively without requiring long thermal curing times
2Ease of operation
If the release layer is made thin to facilitate separation, then laser-induced debonding becomes easier, but the layer becomes more difficult to form uniformly
Solution Approach 1:
The patent replaces mechanical/thermal film formation processes with a chemical vapor deposition or spin-coating method followed by UV photopolymerization. This substitution allows precise control of thin film thickness (on the order of 100s of nanometers to micrometers) while ensuring uniform coverage, because the photosensitive monomers cure rapidly and uniformly upon UV exposure, locking in the uniform thickness achieved during deposition
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 solution enables faster processing times while maintaining the integrity of the bonding layer during high-temperature and mechanical processing steps, and allows for efficient laser-induced debonding without mechanical force.
Implementation Method 1
The thin layer responds to radiation from a laser or other light source, which leads to decomposition of the layer itself or decomposition of the adjacent polymeric bonding material, causing bonding integrity to be lost within the structure
Implementation Method 2
a bonding layer adjacent said front surface
Data Source
Figure 1(a)~1(b)
AI summary
The invention broadly relates to release layer compositions that enable thin wafer handling during microelectronics manufacturing. Preferred release layers are formed from compositions comprising a polyamic acid or polyimide dissolved or dispersed in a solvent system, followed by curing and/or solvent removal at about 250°C to about 350°C for less than about 10 minutes, yielding a thin film. This process forms the release compositions into polyimide release layers that can be used in temporary bonding processes, and laser debonded after the desired processing has been carried out.