Semiconductor Cavity Etching With Uniform Insulating Trenches
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Solution Overview
Problem
Existing methods for manufacturing cavities in semiconductor substrates often result in variable insulating layer thickness, leading to unreliable insulation and potential short-circuits, especially in high-voltage components and critical dimension components.
Innovation Solution
A method that simultaneously forms cavities in both solid semiconductor and semiconductor-on-insulator regions with controlled etching steps and oxidation to create consistent insulating trenches, ensuring uniform insulating layer thickness and shape, including forming first and second portions of the cavities with specific depth and slope differences, and applying an insulating layer by oxidation to achieve rounded or cut-off corner shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cavity manufacturing methods are used, then manufacturing simplicity is maintained, but insulating layer thickness becomes variable leading to unreliable insulation
Solution Approach 1:
The cavity formation process is divided into two distinct portions: a first portion formed by etching through the semiconductor layer, and a second portion formed by etching through the insulating layer. This segmentation allows each portion to be optimized independently, with the insulating layer serving as a natural barrier that ensures uniform thickness in the second portion, thereby resolving the contradiction between manufacturing simplicity and insulating layer thickness uniformity.
2Reliability
If etching is performed to reach the substrate, then complete cavity formation is achieved, but insulating layer thickness becomes variable causing potential short-circuits
Solution Approach 1:
The insulating layer is formed on the cavity walls and bottom before the final etching step that reaches the substrate. This preliminary action ensures that the insulating layer is already in place to prevent short-circuits between the cavity and substrate, eliminating the harmful effect of variable insulating layer thickness while maintaining complete cavity formation.
Solution Approach 2:
The insulating layer acts as a protective cushion formed beforehand on the cavity surfaces. This layer provides a safety margin that prevents direct contact between conductive elements and the substrate, thereby cushioning against the potential harmful effect of short-circuits that could arise from etching variations.
3Productivity
If cavities are formed in different regions simultaneously, then productivity is improved, but manufacturing precision becomes difficult to control
Solution Approach 1:
The etching process is designed to be universal, simultaneously forming both the first portion (through semiconductor layer) and second portion (through insulating layer) of cavities in different regions. The insulating layer serves as a common reference plane that enables precise control of cavity depth and shape across multiple regions, allowing productivity improvement without sacrificing manufacturing precision.
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 ensures reliable insulation in high-voltage components and precise control in critical dimension components by maintaining consistent insulating layer thickness and shape, reducing the risk of short-circuits and enhancing the overall reliability of electronic devices.
Implementation Method 1
the method comprises forming, on the walls and the bottom of the first and second cavities, an insulating layer by oxidation of the substrate
Data Source
AI summary
A substrate includes a first solid semiconductor region and a second semiconductor on insulator region. First and second cavities are simultaneously formed in the first and second regions, respectively, of the substrate using etching processes in two steps which form an upper portion and a lower portion of each cavity. The first and second cavities will each have a step at a level of an upper surface of the insulator of the second semiconductor on insulator region. A further oxidation of the first cavity produces a rounded or cut-off area for the upper portion.