Etching Sacrifice Layer for High Aspect Ratio Polarizing Devices
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Solution Overview
Problem
Existing polarizing devices with high aspect ratio grid patterns face challenges in controlling the endpoint during dry etching, leading to side etching and suboptimal optical properties, particularly when using tungsten masks and TiN undercoat layers.
Innovation Solution
Incorporating an etching sacrifice layer with an etching rate equal to or greater than the metallic film, made of resin materials like methacrylic or acrylic resin, to prevent overetching and enhance control during the etching process, thereby forming a polarizing device with a high aspect ratio and improved optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If dry etching is used to form grid patterns with high aspect ratio and small L/S ratio, then optical property is improved, but side etching occurs and manufacturing precision deteriorates
Solution Approach 1:
The patent applies preliminary action by forming an undercoat layer (etching sacrifice layer) on the base substrate before forming the metallic film. This undercoat layer is etched first during the dry etching process, creating a sacrificial buffer that prevents direct etching of the base substrate and controls the etching endpoint, thereby preventing side etching while maintaining high aspect ratio grid patterns with small L/S ratios for optimal optical properties.
2Ease of manufacture
If TiN layer is used as undercoat layer for Al layer, then manufacturing is simplified, but optical transparency decreases
Solution Approach 1:
The patent applies parameter changes by replacing the TiN undercoat layer with an organic resin material (such as HMDSO, HMDS, or HMDSPA) that has different etching characteristics and optical properties. This resin material provides sufficient etching selectivity and endpoint control while maintaining high optical transparency, thus resolving the contradiction between manufacturing simplicity and optical transparency.
3Reliability
If tungsten mask is used to prevent side etching, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies the taking out principle by removing the complex tungsten mask layer from the etching process. Instead, it uses a simplified undercoat layer made of organic resin material that provides the necessary etching protection and endpoint control. This extraction of the tungsten mask layer reduces process complexity while maintaining reliability in preventing side etching.
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 use of an etching sacrifice layer allows for precise control of the etching endpoint, preventing overetching and enabling the formation of polarizing devices with high aspect ratios and excellent optical properties, while also protecting the device during rubbing processing for liquid crystal applications.
Implementation Method 1
the etching sacrifice layer is partly etched together with the metallic film during the etching of the polarizing device unit
Data Source
AI summary
A polarizing device includes: a polarizing device unit composed of a metallic film formed on a base, the metallic film having a plurality of slit-shaped openings; and an etching sacrifice layer provided between the base and the polarizing device unit, so that the etching sacrifice layer is partly etched together with the metallic film during the etching of the polarizing device unit; wherein the etching sacrifice layer is composed of a material that has an etching rate equal to or greater than that of the metallic film.