Optical Element Etching Process for Fine Stripe Formation
Solution Overview
Problem
The existing manufacturing process for optical elements, such as wire grid polarization elements, faces challenges in forming finely striped reflection layers due to variations in etching rates between different materials, leading to reduced width and increased side etching, which complicates the production of small and fine polarization elements with optimal contrast and brightness.
Innovation Solution
The solution involves forming reflection layers first, followed by an absorbing layer and an oxide film, with the oxide film covering the absorbing layer and the spaces between reflection layers, which reduces etching variations and allows for the formation of finely striped reflection layers with improved contrast and brightness, and includes the use of materials like aluminum, silver, and silicon for the reflection and absorbing layers, respectively, and silicon oxide for the dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a multilayer composite is etched at one time using a resist pattern as a mask, then the manufacturing process is simplified, but the etching amount varies due to different etching rates between layers, causing excessive side etching and reduced stripe width
Solution Approach 1:
The patent divides the multilayer structure into separate aluminum layers and silicon layers that are etched independently at different stages. First, the aluminum layers are etched to form the grid pattern, then the silicon layers are etched separately. This segmentation allows each layer to be etched with optimal parameters, preventing the cross-contamination of etching processes and eliminating the variation in etching amounts that occurs when all layers are etched simultaneously.
2Reliability
If the grid has a multilayer structure with large aspect ratio, then the optical performance is improved, but the etching variation between layers with different etching rates causes difficulty in forming small and fine polarization elements
Solution Approach 1:
The patent performs preliminary etching of the aluminum layers before etching the silicon layers. By first forming the aluminum grid pattern with appropriate etching parameters, then subsequently etching the silicon layers to the required depth, the process ensures that the high-aspect-ratio structures are formed with precise control. This preliminary action allows each material layer to be processed with its optimal etching conditions, maintaining both the large aspect ratio needed for optical performance and the precision required for fine stripe formation.
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 enables the production of optical elements with enhanced contrast and brightness by minimizing etching variations and maintaining optical transmittance between reflection layers, resulting in improved performance for applications like projectors.
Implementation Method 1
an oxide film covering the absorbing layer and portions between any two adjacent reflection layers. The oxide film is made of an oxide of a material contained in the absorbing layer
Data Source
AI summary
An optical element includes a substrate, a plurality of reflection layers disposed on one side of the substrate, an absorbing layer disposed on a side of the reflection layers that is opposite to the substrate, and an oxide film that covers the absorbing layer and portions between any two adjacent reflection layers. The reflection layers are arranged in a striped manner in plan view. The oxide film is made of an oxide of a material contained in the absorbing layer.