Silicon Carbide Etching with Oxidized Layer Control
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Solution Overview
Problem
The formation of micro-trenches during the etching of silicon carbide materials leads to reduced working reliability and service life of semiconductor devices, necessitating precise and controllable etching methods.
Innovation Solution
An etching method involving a patterned mask layer, where an oxidizing gas forms a modified layer on the exposed surface, followed by removal with an etching gas, ensuring precise control and avoiding over-etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching is used on silicon carbide, then etching can be performed, but micro-trenches form at the bottom of sidewalls reducing device reliability
Solution Approach 1:
The patent applies preliminary action by first forming a modified layer on the silicon carbide surface through oxidation before performing the actual etching. This pre-modification step creates a distinct layer that can be selectively removed, preventing direct etching damage to the underlying silicon carbide and avoiding micro-trench formation at sidewall bottoms.
Solution Approach 2:
The etching process is segmented into two distinct stages: first forming a modified layer through oxidation, then selectively etching this modified layer. This segmentation separates the modification function from the removal function, allowing precise control over etching depth and preventing over-etching that causes micro-trenches.
2Manufacturing precision
If etching continues to achieve desired depth, then trench can be formed, but over-etching occurs causing micro-trenches
Solution Approach 1:
The modified layer serves as an intermediary between the etching gas and the silicon carbide substrate. The etching gas selectively removes this intermediate layer while sparing the underlying silicon carbide, providing a self-limiting etching process that prevents micro-trench formation by stopping etching at the appropriate position.
Solution Approach 2:
The patent changes the chemical state of the silicon carbide surface by oxidizing it to form a modified layer with different properties. This parameter change in material composition enables selective etching of the modified layer while protecting the original silicon carbide from over-etching and micro-trench formation.
3Ease of manufacture
If direct etching is performed on silicon carbide, then trench formation is achieved, but electrical damage occurs
Solution Approach 1:
The oxidation step is performed as a preliminary action before etching, creating a protective modified layer that prevents electrical damage during the subsequent etching process. This additional step, while increasing process complexity, eliminates harmful electrical damage effects.
Solution Approach 2:
The oxidation process, which initially seems to add complexity, converts the silicon carbide surface into a modified layer that is more susceptible to selective etching. This transformation turns a potential disadvantage (additional process step) into a benefit by enabling precise etching control and preventing electrical damage to the substrate.
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 method prevents the formation of micro-trenches, reducing electrical damage and enhancing device performance by allowing the etching process to stop at the appropriate position.
Implementation Method 1
modifying an exposed surface of the structure to be etched by using an oxidizing gas while taking the mask layer as a shield, so as to form a modified layer
Implementation Method 2
removing the modified layer by using an etching gas while taking the mask layer as the shield, so as to form a trench
Data Source
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AI summary
An etching method and an etching system. The etching method comprises: providing a structure to be etched (101), wherein said structure (101) is covered with a patterned mask layer (102); modifying an exposed surface of said structure (101) by taking the mask layer (102) as a mask and using an oxidizing gas, so as to form a modified layer (103); and removing the modified layer (103) by taking the mask layer (102) as a mask and using an etching gas, so as to form a trench (104).