Irregular Microtextured LED Chips for Low-Crosstalk Light Extraction
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Solution Overview
Problem
Conventional methods for manufacturing LED devices with small pixel pitches face challenges in reliable implementation due to difficulties in preventing light crosstalk and achieving uniform light emission, particularly with bevel-cutting techniques that are time-consuming, prone to substrate cracking, and result in non-uniform lumiphoric material thickness.
Innovation Solution
The development of LED chips with a microtextured etched surface featuring a non-repeating, irregular textural pattern, formed by using a micromask with different etching rates and reactive ion etching, which reduces light spillover and allows for uniform lumiphoric material application, enhancing light extraction and array resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If bevel-cutting techniques are used to create light extraction surfaces, then light extraction is improved, but the manufacturing process becomes time-consuming and prone to substrate cracking
Solution Approach 1:
The patent replaces the mechanical bevel-cutting process with a chemical etching process using reactive ion etching (RIE). This substitution eliminates the mechanical stress and time-consuming nature of bevel-cutting while achieving the desired light extraction surface morphology through controlled chemical reactions that create the microtextured pattern.
Solution Approach 2:
The patent changes the fundamental parameter of surface creation from mechanical removal (bevel-cutting) to chemical etching (RIE). By controlling etching parameters such as gas composition, power, and time, the process achieves the desired surface morphology without the drawbacks of mechanical cutting, thereby improving both light extraction efficiency and manufacturing productivity.
2Illumination intensity
If bevel-cutting techniques are used to create light extraction surfaces, then light extraction is improved, but substrate cracking occurs reducing manufacturing yield
Solution Approach 1:
The patent replaces the mechanical bevel-cutting process with a chemical etching process using reactive ion etching (RIE). This substitution eliminates the mechanical stress and time-consuming nature of bevel-cutting while achieving the desired light extraction surface morphology through controlled chemical reactions that create the microtextured pattern.
Solution Approach 2:
The patent introduces a micromask as an intermediary layer that protects specific areas of the substrate during etching. This mask allows precise control over where etching occurs, preventing uncontrolled mechanical stress propagation that leads to cracking, while still achieving the desired light extraction enhancement in the exposed regions.
3Illumination intensity
If bevel-cutting techniques are used, then light extraction surface is created, but lumiphoric material thickness becomes non-uniform
Solution Approach 1:
The patent introduces a micromask as an intermediary layer that protects specific areas of the substrate during etching. This mask allows precise control over where etching occurs, preventing uncontrolled mechanical stress propagation that leads to cracking, while still achieving the desired light extraction enhancement in the exposed regions.
Solution Approach 2:
The patent applies the micromask pattern to the substrate before the etching process begins. This preliminary action defines the exact regions that will be etched and protects areas where uniform lumiphoric material deposition is critical, ensuring that subsequent material application results in uniform thickness across the light extraction surface.
4Measurement precision
If conventional LED arrays are used with small pixel pitches, then resolution is improved, but light crosstalk between adjacent pixels increases
Solution Approach 1:
The patent segments the light extraction surface into distinct etched and unetched regions using micromask patterning. This segmentation creates optical isolation between adjacent pixels, allowing high-resolution arrays with small pixel pitches to maintain low crosstalk by physically separating the light emission zones through the textured surface pattern.
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 approach improves light extraction efficiency, reduces crosstalk, and maintains manufacturing yield by creating a uniform lumiphoric layer, resulting in improved contrast and sharpness in LED arrays without the limitations of bevel-cutting methods.
Implementation Method 1
exposing the micromask to an etchant (e.g., via reactive ion etching) to form a microtextured etched surface having a non-repeating, irregular textural pattern
Data Source
AI summary
LED chips and related fabrication methods are disclosed. A LED chip includes an active layer arranged on or over a light-transmissive substrate having a light extraction surface. The light extraction surface comprises a microtextured etched surface having a non-repeating, irregular textural pattern (e.g., with an average feature depth in a range of from 120 nm to 400 nm, and preferably free of any plurality of equally sized, shaped, and spaced textural features). The microtextured etched surface may be formed by applying a micromask having first and second solid materials of different etching rates over the light extraction surface, and exposing the micromask to an etchant (e.g., via reactive ion etching) to form a microtextured etched surface having a non-repeating, irregular textural pattern. Lumiphoric material may be applied over the microtextured surface.