Ion Source Grid Structure for Uniform Slanted Grating Etching
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Solution Overview
Problem
The issue of poor wafer uniformity during the fabrication of slanted gratings using ion beam etching arises due to non-uniform etching distances, requiring costly and inefficient iterative adjustments of processing parameters.
Innovation Solution
The grid structure of the ion source apparatus is optimized by adjusting the screen and acceleration grids such that the equivalent distance of the grid structure increases or decreases monotonically along the direction perpendicular to the ion beam extraction, altering the current and density of the extracted ion beam to enhance etching uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a wafer is placed with a certain oblique angle with respect to the grid structure for slanted grating fabrication, then the diffraction efficiency is improved, but the etching uniformity across the wafer deteriorates due to different etching distances
Solution Approach 1:
The patent applies local quality by making different regions of the screen grid have different thicknesses. Specifically, the screen grid is designed with a first region having a first thickness and a second region having a second thickness different from the first thickness. This allows each region to compensate for the varying etching distances caused by the oblique wafer placement, thereby maintaining uniform etching rates across the entire wafer surface while preserving the oblique angle configuration needed for high diffraction efficiency
Solution Approach 2:
The patent changes the physical parameter of the screen grid thickness to compensate for the non-uniform etching distances. By varying the thickness parameter of the screen grid in different regions, the ion beam travel distance is equalized across different wafer areas, thus achieving uniform etching rates while maintaining the oblique configuration for optimal diffraction efficiency
2Manufacturing precision
If iterative adjustments of processing parameters are made to achieve satisfactory etching uniformity, then the manufacturing precision is improved, but the production time and cost increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the screen grid with non-uniform thickness distribution before the etching process begins. This upfront design eliminates the need for iterative parameter adjustments during production, as the thickness variation is specifically engineered to compensate for the oblique etching geometry. The result is achieved etching uniformity without the time-consuming iterative adjustment cycle
Solution Approach 2:
The screen grid structure serves itself by using its own thickness variation to automatically compensate for the non-uniform etching distances. The different thickness regions inherently adjust the ion beam path lengths, creating self-equalizing etching conditions across the wafer without requiring external intervention or iterative parameter tuning during the manufacturing process
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 the overall uniformity of slanted grating fabrication by enhancing the etching rate in areas with slow etching and reducing it in areas with fast etching, eliminating the need for iterative parameter adjustments, thus being cost-effective and efficient.
Implementation Method 1
Through altering a geometric feature and a relative position of grids and controlling a potential distribution on the grids, the ion grid structure can extract ions from the discharge chamber
Implementation Method 2
When fabricating the slanted grating through ion beam etching, a wafer needs to be placed with a certain oblique angle with respect to the grid structure
Data Source
Figure 1~2B
Figure 3~4B
Figure 5~6
AI summary
Disclosed are an ion beam device, an ion source apparatus and a grid structure thereof. The grid structure is used to guide out an ion beam. The grid structure comprises screen grids (1, 1a, 1b, 1c, 1d, 1e) and acceleration grids (2, 2a, 2b, 2c, 2d, 2e), the two being arranged in parallel at intervals. Along a direction perpendicular to the direction of the ion beam being guided out, an equivalent distance of the grid structure has an increasing trend or a decreasing trend, the equivalent distance being the sum of the equivalent thickness of the screen grids (1, 1a, 1b, 1c, 1d, 1e) and the distance between the screen grids (1, 1a, 1b, 1c, 1d, 1e) and the acceleration grids (2, 2a, 2b, 2c, 2d, 2e). By means of optimizing the grid structure of the ion source apparatus, the overall uniformity of an inclined grating can be ensured during inclined grating processing, the cost is low, and the efficiency is high.