Rounded Wall Semiconductor Structure for High-Voltage Dielectrics
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Solution Overview
Problem
Existing silicon-integrated capacitive structures are unsuitable for high-voltage applications due to poor permeability to processing gases, high mechanical stress, and increased probability of defects from thick dielectric layers, which are exacerbated by sharp corners and narrow trenches.
Innovation Solution
A substrate with a protruding wall structure featuring rounded corners and an open geometry, allowing for easier etching and oxide deposition, reduced mechanical stress, and uniform dielectric layer thickness, facilitating the use of thicker dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick dielectric layer is used to sustain the operating electrical field for high-voltage applications, then the electrical field margin is improved, but the mechanical stress and probability of defects (dielectric cracking or delamination) increase significantly
Solution Approach 1:
The patent applies curvature by rounding the corners of the trench structure. This spherical/curved geometry distributes mechanical stress more uniformly across the dielectric layer, preventing stress concentration at sharp corners that would lead to cracking or delamination. This allows thick dielectric layers to be used for high-voltage applications without exacerbating mechanical stress problems.
2Quantity of substance
If narrow trenches are used to achieve high capacitance density, then the capacitance density is improved, but the permeability to processing gases deteriorates, complicating etching and deposition processes
Solution Approach 1:
The patent segments the continuous trench structure into discrete, separated trench elements. This segmentation creates open spaces between trenches that allow processing gases to penetrate and circulate effectively during etching and deposition processes, while still maintaining high capacitance density through the overall array configuration.
3Quantity of substance
If cylindrical capillaries are etched to form 3D capacitors, then the capacitance structure is achieved, but the mechanical stress leads to substantial wafer warpage
Solution Approach 1:
The patent uses curved/rounded trench corners instead of sharp angles, which distributes mechanical stress more evenly throughout the structure. This reduces the cumulative mechanical stress that causes wafer warpage while maintaining the 3D capacitive structure functionality.
4Ease of manufacture
If sharp corners are present in the trench structure, then the manufacturing process is simplified, but the electrical stress concentration increases, reducing breakdown voltage
Solution Approach 1:
The patent implements rounded corners in the trench structure to eliminate sharp edges that concentrate electrical stress. This curvature distributes the electrical field more uniformly, increasing the breakdown voltage and improving reliability for high-voltage applications.
5Length of stationary object
If a thick dielectric layer is deposited over sharp edges or corners, then the dielectric thickness is increased for high-voltage capability, but the mechanical stress causes dielectric cracking or delamination
Solution Approach 1:
The patent rounds the corners of the trench structure before depositing the thick dielectric layer. This curved geometry provides a uniform substrate that distributes mechanical stress evenly during dielectric deposition, preventing stress concentration that would cause cracking or delamination, thereby maintaining dielectric integrity even at large thicknesses.
Data Source
AI summary
A semiconductor structure that includes a protruding wall structure that extends from a base surface of a substrate. Corners of the protruding wall structure may be smoothed or rounded to reduce electrical stress within the structure. The protruding wall structure may be partitioned into multiple wall regions disposed along different directions of the substrate to reduce mechanical stress.