Laser-Absorbing Laminate for Residue-Free Semiconductor Transfer
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Solution Overview
Problem
Existing semiconductor element transfer methods face limitations such as area-related constraints, high cost, and potential damage from excessive laser energy, leading to adhesive residue and reduced yield, especially in the laser lift-off technique.
Innovation Solution
A laminate structure comprising a laser-transparent substrate and resin films with specific absorbance and adhesive strength properties, allowing wide-range laser beam usage without adhesive residue or element damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser lift-off technique is used to transfer chips with high speed and high positional accuracy, then transfer efficiency is improved, but adhesive residue and element damage occur due to excessive laser energy
Solution Approach 1:
The adhesive layer is divided into two separate functional layers: a lower adhesive layer for bonding and an upper laser absorption layer for selective removal. This segmentation allows the laser energy to be absorbed specifically by the absorption layer without excessively heating or damaging the semiconductor element or substrate, thereby enabling high-speed transfer while preventing adhesive residue and element damage.
Solution Approach 2:
The laser absorption layer acts as an intermediary between the laser beam and the adhesive layer. It absorbs the laser energy and converts it to thermal energy, which then heats the adhesive layer for removal. This intermediary protects the semiconductor element and substrate from direct exposure to excessive laser energy, preventing damage while still enabling efficient adhesive removal for high-speed transfer.
2Manufacturing precision
If a very thin adhesive layer is formed to enable complete removal by laser ablation, then transfer completeness is improved, but in-plane uniformity decreases leading to reduced yield
Solution Approach 1:
The adhesive system is segmented into two layers with distinct functions: the lower adhesive layer provides bonding strength and can be made thicker for better uniformity, while the upper laser absorption layer is specifically designed to absorb laser energy for complete and uniform removal. This segmentation allows the adhesive layer to be thicker without compromising transfer completeness, thereby improving in-plane uniformity and yield.
Solution Approach 2:
The invention changes the optical parameters of the adhesive system by introducing a laser absorption layer with specific optical absorption characteristics. This layer is designed to absorb laser energy at the chosen wavelength, enabling complete and uniform removal of the adhesive layer regardless of its thickness. This parameter change allows for thicker adhesive layers with better in-plane uniformity while maintaining complete transfer removal.
3Productivity
If adhesive layer removal is achieved by laser ablation, then transfer efficiency is improved, but the range of laser energy is narrow and process margin is reduced
Solution Approach 1:
The invention introduces a laser absorption layer with specific optical absorption characteristics that can be tuned to match various laser wavelengths. By selecting appropriate absorption materials and adjusting their concentration and thickness, the system can efficiently absorb laser energy across a wide range of wavelengths and power levels. This parameter adjustment capability expands the usable laser energy range and provides a larger process margin while maintaining high transfer efficiency.
Solution Approach 2:
The laser absorption layer is designed with specific local optical properties (absorption coefficient, thickness, material composition) that can be optimized for different laser parameters. This local quality control allows the same adhesive system to work efficiently with various laser wavelengths and power levels, expanding the process window and adaptability while maintaining high transfer efficiency.
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 efficient transfer of semiconductor elements with high positional accuracy and reduced damage, overcoming limitations of previous methods by providing a wide process margin and improved yield.
Implementation Method 1
the absorbance of the resin film 1 converted to a film thickness of 1.0 μm is 0.4 or more and 5.0 or less at a wavelength in the range of 200 to 1,100 nm
Implementation Method 2
a laminate including a substrate 1 with laser transparency, a resin film 1, and a resin film 2 stacked in this order
Data Source
AI summary
Provided is a laminate that can be implemented with a wide processing margin and without adhesive residue or damage to a semiconductor element in the transfer of the semiconductor element using laser light of various wavelengths. The laminate is obtained by laminating a substrate 1 having laser permeability, a resin film 1 and a resin film 2 in this order, wherein the light absorbance of the resin film 1 calculated for a film thickness of 1.0 μm at any wavelength of 200 nm to 1100 nm is 0.4-5.0, and the adhesive strength of the surface of the resin film 2 on the side opposite that of the resin film 1 side is 0.02-0.3 N/cm.