Micro-Display Fabrication Trench Pattern Aperture Ratio
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Solution Overview
Problem
Micro-display devices using LCOS technology face limitations in achieving a higher aperture ratio and improved light reflectivity due to constraints in the photolithographic process, which affects their performance.
Innovation Solution
A process involving the formation of a trench pattern using an anti-reflection layer and a dielectric layer on a metallic reflective layer, with the patterned photoresist layer as an etching mask, to increase the aperture ratio and reduce gap dimensions, thereby enhancing light reflectivity and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithographic process is used to fabricate micro-display, then manufacturing process is simple, but aperture ratio is limited and light reflectivity is insufficient
Solution Approach 1:
The fabrication process is divided into multiple sequential steps: forming anti-reflection layer, forming dielectric layer, forming photoresist pattern, etching trench patterns, and selective removal of layers. This segmentation allows each step to be optimized independently, achieving high aperture ratio through precise trench pattern formation while managing overall process complexity through systematic organization of fabrication steps.
Solution Approach 2:
The anti-reflection layer and dielectric layer are formed in advance before the etching process. These preliminary layers serve as etching masks that enable precise trench pattern formation. By preparing these layers beforehand, the process achieves high manufacturing precision for aperture ratio control while the systematic sequence manages fabrication complexity.
2Reliability
If metallic reflective layer completely covers pixel region, then image display capacity is improved, but aperture ratio is reduced due to transistor coverage
Solution Approach 1:
The metallic reflective layer is selectively removed in the pixel region through trench pattern etching, creating local variations in reflectivity. The trench patterns expose the underlying wafer surface in specific areas, allowing light to pass through while maintaining reflective coverage in other areas. This local quality approach simultaneously maintains image display capacity through overall metallic coverage and increases aperture ratio through selective removal in pixel regions.
Solution Approach 2:
The metallic reflective layer coverage is segmented into different regions: areas with trench patterns that expose the wafer surface (increasing aperture ratio) and areas where the metallic layer remains intact (maintaining image display capacity). This spatial segmentation resolves the contradiction by allowing both functions to coexist in different locations on the same device.
3Ease of manufacture
If photolithographic process limitations are accepted, then fabrication is easier, but aperture ratio and light reflectivity remain moderate
Solution Approach 1:
The anti-reflection layer and dielectric layer serve as intermediary etching masks between the photoresist pattern and the metallic reflective layer. These intermediary layers enable precise trench pattern formation by providing a controlled etching interface, allowing the photolithographic process to achieve higher manufacturing precision for aperture ratio while maintaining relative ease of manufacture through standard etching techniques.
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 process results in a micro-display with increased aperture ratio and improved light reflectivity, breaking through photolithographic limitations and enhancing device performance by defining smaller trench patterns and using the anti-reflection or dielectric layers as etching masks.
Implementation Method 1
Using the patterned photoresist layer as an etching mask, the anti-reflection layer and the metallic reflective layer are etched to form a trench pattern
Implementation Method 2
a metallic reflective layer is formed on the wafer... increasing the aperture ratio and the reflectivity of light
Data Source
AI summary
A process for fabricating a micro-display is provided. First, a wafer having a driving circuit thereon is provided. Then, a metallic reflective layer is formed on the wafer. Thereafter, an anti-reflection layer and a patterned photoresist layer are sequentially formed on the metallic reflective layer. Using the patterned photoresist layer as an etching mask, the anti-reflection layer and the metallic reflective layer are etched to form a trench pattern that exposes the surface of the wafer. After that, the patterned photoresist layer is removed. A dielectric layer is formed to cover the anti-reflection layer and fill the trench pattern. Then, a portion of the dielectric layer and the anti-reflection layer are removed to expose the surface of the metallic reflective layer.