Etch Mask Layout for Deep Symmetric Cavity Formation
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Solution Overview
Problem
Existing cavity forming methods struggle to create deep cavities with controlled wall curvature and symmetry, leading to increased leakage risks and difficulty in maintaining layer thickness during etching, especially for power components requiring voltages above 800 V.
Innovation Solution
A method involving a photolithography mask with specific ratios of openings and sets of openings to control cavity depth and curvature, combined with wet etching, ensures symmetrical and controlled cavity formation, using an insulating and protection layer to maintain layer integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional etching methods are used to create deep cavities, then cavity depth can be increased, but control over wall curvature and symmetry deteriorates
Solution Approach 1:
The mask is divided into multiple sets of openings (first set, second sets) with different opening-to-mask ratios. The first set has a higher ratio for creating the deep central cavity, while the second sets have lower ratios for controlling the wall curvature and symmetry. This segmentation allows different regions of the mask to serve different functional purposes in the cavity formation process.
Solution Approach 2:
Different regions of the mask are assigned different opening-to-mask ratios tailored to their specific functions. The central region (first set) uses a higher ratio to achieve deep cavity penetration, while the peripheral regions (second sets) use lower ratios to control wall curvature and maintain symmetry. This local differentiation of mask properties enables precise control over the cavity's geometric characteristics at each location.
2Length of stationary object
If conventional etching methods are used to create deep cavities, then cavity depth can be increased, but leakage risk increases
Solution Approach 1:
The mask is divided into multiple sets of openings (first set, second sets) with different opening-to-mask ratios. The first set has a higher ratio for creating the deep central cavity, while the second sets have lower ratios for controlling the wall curvature and symmetry. This segmentation allows different regions of the mask to serve different functional purposes in the cavity formation process.
Solution Approach 2:
Different regions of the mask are assigned different opening-to-mask ratios tailored to their specific functions. The central region (first set) uses a higher ratio to achieve deep cavity penetration, while the peripheral regions (second sets) use lower ratios to control wall curvature and maintain symmetry. This local differentiation of mask properties enables precise control over the cavity's geometric characteristics at each location.
3Ease of manufacture
If conventional etching methods are used, then cavity formation can be achieved, but difficulty in maintaining layer thickness increases
Solution Approach 1:
The mask is prepared in advance with specifically designed sets of openings having predetermined opening-to-mask ratios. The first set of openings is configured with a higher ratio to facilitate deep cavity formation, while the second sets are pre-configured with lower ratios to maintain layer thickness and control etching progression. This preliminary configuration of the mask structure enables the etching process to proceed with built-in control mechanisms that maintain layer thickness throughout the cavity formation process.
4Length of stationary object
If multiple openings are used to form deep cavities, then cavity depth increases, but control over symmetry deteriorates
Solution Approach 1:
The mask employs different opening-to-mask ratios for different sets of openings, creating an asymmetric distribution of opening sizes and densities. The first set has a higher ratio while the second sets have lower ratios, creating intentional asymmetries in the mask structure that compensate for potential asymmetries in the etching process. This controlled asymmetry in the mask design ensures symmetric cavity formation by balancing the etching rates and material removal patterns across different regions.
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
Enables the formation of deep cavities with reduced leakage risks and improved control over wall curvature, allowing for the manufacturing of power components capable of withstanding higher voltages by maintaining layer thickness and symmetry.
Implementation Method 1
the wet etching of the substrate through the openings
Data Source
AI summary
The present description concerns a method of forming a cavity in a substrate comprising: the forming of an etch mask comprising, opposite the location of the cavity, a plurality of sets of openings, the ratio between the openings and the mask of each set being selected according to the desired profile of the cavity opposite the surface of the mask having the set inscribed therein; and the wet etching of the substrate through the openings.