Substrate Separation Device with U-Shaped Susceptor for Laser Lift-Off
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Solution Overview
Problem
The laser lift-off method for separating growth substrates in LED manufacturing often fails due to thermal expansion differences between substrates, causing bowing and inaccurate laser beam focus, which can result in incomplete separation and damage to substrates.
Innovation Solution
A substrate separation device and system that includes a susceptor with a U-shaped or V-shaped recess to evenly heat the laminate structure, a laser irradiation unit to separate the growth substrate, and a substrate separation device with vacuum holding units to manage the separation process, ensuring accurate and complete separation while preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the growth substrate and support substrate are bonded together, then the laser lift-off separation can be performed, but thermal expansion differences cause bowing which changes the laser focal point and prevents accurate energy transmission to the interface
Solution Approach 1:
A susceptor is introduced as an intermediary component between the growth substrate and support substrate. The susceptor has a U-shaped or V-shaped recess that receives the growth substrate, and its curved surface profile is specifically designed to counteract the bowing tendency of the bonded substrates during heating, thereby maintaining the laser focal point at the interface between the growth substrate and semiconductor layer.
Solution Approach 2:
The patent changes the geometric parameters of the susceptor, specifically designing it with a U-shaped or V-shaped recess rather than a flat surface. This parameter change allows the susceptor to provide mechanical support that compensates for thermal expansion differences, preventing substrate bowing while enabling accurate laser focus during the separation process.
2Temperature
If conventional heating methods are used, then the separation process can proceed, but uneven heating occurs leading to inaccurate laser beam focus and potential substrate damage
Solution Approach 1:
The susceptor acts as a thermal intermediary that distributes heat evenly across the growth substrate and support substrate assembly. Its design with a U-shaped or V-shaped recess ensures uniform thermal contact and heating, preventing localized overheating or uneven temperature distribution that would otherwise cause focal point shifts and separation inaccuracies.
3Productivity
If laser beam irradiation is applied to separate the growth substrate, then separation can be achieved, but defects, metal film deposition, or contamination cause partial epitaxial layer remaining which damages the substrates
Solution Approach 1:
The patent employs a feedback mechanism where the susceptor design and heating process are optimized to ensure complete laser penetration and separation. By maintaining accurate focal point positioning through the susceptor's geometric design and uniform heating, the system ensures that the laser energy is sufficiently transmitted through the interface, preventing partial separation that would leave epitaxial layers or buffer layers behind and cause substrate damage.
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 solution effectively alleviates substrate bowing, ensures accurate laser beam transmission, and prevents damage by evenly heating the laminate structure and using vacuum adsorption to manage the separation process, resulting in successful separation of growth substrates without cracking or breaking.
Implementation Method 1
a heating unit configured to heat the laminate structure
Implementation Method 2
The first holding unit and the second holding unit may be configured to selectively hold the support substrate and the growth substrate through vacuum adsorption, respectively
Implementation Method 3
irradiating a laser beam through the growth substrate to separate the growth substrate from the epitaxial layers
Implementation Method 4
an exhaust pump configured to generate an air stream drawing in (or intaking) foreign objects through the exhaust pipe
Data Source
AI summary
There is provided a substrate separation device and method for separating a growth substrate from a laminate structure which includes a support substrate, a semiconductor layer, and the growth substrate. The device includes: a first base which is configured to hold the laminate structure thereon, and includes a first holding unit configured to hold the support substrate defining a bottom surface of the laminate structure and a heating unit configured to heat the laminate structure; and a second base including a second holding unit disposed above the first holding unit and configured to hold the growth substrate defining an upper surface of the laminate structure.