UV-LED Wafer Laser Scribing for Brightness Without Epitaxial Heat Damage
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Solution Overview
Problem
The challenge in manufacturing ultraviolet light emitting diodes (UV-LEDs) is to shorten the spacing between laser scratches and the semiconductor stacked layer while maintaining the splitting yield, as existing methods damage the epitaxial light emitting layer due to high-energy heat, leading to poor splitting yield and reduced brightness.
Innovation Solution
A manufacturing method involving the use of quasi-circular laser scratches close to the semiconductor stacked layer, formed by multiple low-energy laser cutting lines, which increases light emission and reduces the incident angle, thereby improving brightness and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the spacing between laser scratches and the semiconductor stacked layer is reduced to improve brightness, then light extraction is enhanced, but the epitaxial light emitting layer is damaged due to high-energy heat
Solution Approach 1:
The single high-energy laser cutting line is segmented into multiple low-energy laser cutting lines. Specifically, the first laser cutting line is divided into at least two separate cutting lines, which reduces the energy concentration at any single point while maintaining the overall cutting function. This segmentation allows the laser scratches to be positioned closer to the semiconductor stacked layer without causing heat damage to the epitaxial light emitting layer.
Solution Approach 2:
Different laser cutting lines are assigned different energy levels based on their position relative to the semiconductor stacked layer. The first laser cutting line (closer to the semiconductor layer) uses lower energy to avoid heat damage, while the second laser cutting line (farther from the semiconductor layer) uses higher energy to ensure complete separation. This local quality differentiation optimizes both light extraction and layer protection.
2Reliability
If multiple low-energy laser cutting lines are used to reduce heat damage, then the epitaxial layer is protected, but the light extraction efficiency is reduced
Solution Approach 1:
Multiple laser cutting lines are combined to achieve the function of a single high-energy cutting line while avoiding its harmful effects. The at least two low-energy cutting lines of the first laser cutting line work together to create the necessary separation, and their combined effect with the second laser cutting line achieves complete wafer separation while protecting the epitaxial layer and enhancing light extraction through optimized scratch positioning.
Solution Approach 2:
The solution transitions from a single-dimension approach (one high-energy cutting line) to a multi-dimensional approach (multiple cutting lines at different positions and energy levels). The first laser cutting line is divided into at least two separate cutting lines positioned at different locations, creating a multi-dimensional laser processing scheme that simultaneously achieves layer protection and light extraction enhancement.
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 effectively increases light extraction and brightness of UV-LEDs by reducing the spacing between laser scratches and the semiconductor stacked layer, while maintaining the splitting yield, by using quasi-circular explosion points and multiple low-energy laser cutting lines.
Implementation Method 1
providing and focusing laser beams including a first laser beam and a second laser beam into the substrate, a focusing position of the first laser beam is closer to the lower surface of the semiconductor stacked layer than a focusing position of the second laser beam, the first laser beam is focused into the substrate to form at least one first laser cutting line
Data Source
AI summary
Provided are an ultraviolet light emitting diode (LED) and a manufacturing method thereof. The manufacturing method includes: providing an LED wafer including a substrate and a semiconductor stacked layer, the semiconductor stacked layer has a lower surface and an upper surface, the semiconductor stacked layer includes a first semiconductor layer, a light emitting layer and a second semiconductor layer; focusing a first laser beam and a second laser beam into the substrate, a focusing position of the first laser beam is closer to the lower surface than that of the second laser beam, the first laser beam is focused to form at least one first laser cutting line, laser scratches of each first laser cutting line are quasi-circular, and the at least one first laser cutting line includes a laser cutting line closest to the lower surface; and separating the LED wafer to form LED chips.