Patterned Substrate Manufacturing via Step-and-Repeat Photolithography
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Solution Overview
Problem
Semiconductor light emitting elements, particularly gallium nitride-based, face low light extraction efficiency due to total reflection caused by high refractive index differences between the semiconductor layer and surrounding air, leading to reduced light emission outside the device.
Innovation Solution
A method of manufacturing a patterned substrate with reduced distortion of protruding portions by using a specific exposure mask design and step-and-repeat photolithography process, where inner and outer light-shielding portions are arranged to minimize alignment errors and overlapping exposure regions, resulting in a substrate with optimized light scattering properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a photoresist layer is exposed multiple times in a step-and-repeat manner using a conventional exposure mask, then the productivity is improved by forming large-area patterns efficiently, but the manufacturing precision deteriorates due to alignment errors and distortion of the protruding portions pattern
Solution Approach 1:
The exposure mask is divided into multiple light-shielding portions (first, second, third light-shielding portions) that correspond to different exposure fields. Each light-shielding portion is designed with specific dimensions and positions to control the exposure regions independently, allowing precise alignment and reducing cumulative distortion across multiple exposure steps.
Solution Approach 2:
The exposure mask is designed in advance with predetermined light-shielding portions that account for potential alignment errors and distortion. The first light-shielding portion has a larger dimension in the first direction to compensate for alignment variations, and the overlapping regions between exposure fields are pre-planned to minimize pattern distortion.
2Reliability
If the light-shielding portions are arranged to overlap in all regions, then the alignment tolerance is improved, but the manufacturing precision deteriorates due to excessive exposure in overlapping regions causing distortion
Solution Approach 1:
The exposure mask design implements local quality by having different light-shielding portions with varying dimensions and positions. The first light-shielding portion has a larger dimension in the first direction, while the second light-shielding portion has a larger dimension in the second direction. This local variation optimizes alignment tolerance in different directions while controlling exposure intensity in overlapping regions to prevent distortion.
Solution Approach 2:
The light-shielding portions are designed to overlap partially rather than completely. The overlapping regions are controlled to provide sufficient alignment tolerance while avoiding excessive exposure that would cause pattern distortion. The third light-shielding portion is positioned to overlap with both first and second light-shielding portions in a controlled manner.
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 reduces distortion and positional errors in the patterned substrate, enhancing light extraction efficiency by varying the angle of emitted light and reducing defects in semiconductor layers, thereby improving the yield and performance of semiconductor light emitting devices.
Implementation Method 1
exposing a photoresist layer disposed on a substrate a plurality of times in a step-and-repeat-manner using the exposure mask
Implementation Method 2
etching the substrate using the developed photoresist layer as a mask
Implementation Method 3
scatter light emitted from the semiconductor layer on the surface of the substrate
Data Source
AI summary
A method of manufacturing a patterned substrate includes: providing an exposure mask that includes: a plurality of inner light-shielding portions arranged in a lattice, a light-transmissive portion integrally connecting regions surrounding the plurality of inner light-shielding portions, and an outer light-shielding portion surrounding the light-transmissive portion; performing a plurality of exposures of a photoresist layer disposed on a substrate in a step-and-repeat-manner using the exposure mask, so as to form a plurality of inner projected parts corresponding to the inner light-shielding portions, the inner projected parts being aligned in a lattice as a whole; developing the photoresist layer on which the plurality of exposures have been performed; and etching the substrate using the developed photoresist layer as a mask.