SiC Schottky Contact Etching Around Ohmic Electrode Interfaces
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Solution Overview
Problem
The fabrication process of silicon carbide semiconductor devices with built-in Schottky Barrier Diodes (SBD) faces issues where hydrofluoric acid etching can erode the interface between ohmic electrodes and resist masks, leading to unexpected etching and potential defects in the gate-dielectric film and isolation failures.
Innovation Solution
A method is introduced that involves forming a dielectric film over a silicon carbide layer, forming an ohmic electrode adjacent to the dielectric film, removing the oxidized layer on the ohmic electrode, creating a resist mask with an opening opposite to the ohmic electrode, and performing wet etching with hydrofluoric acid, followed by removing the resist mask to prevent unwanted etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the passivation film is wet etched with hydrofluoric acid to form the Schottky contact, then the Schottky contact can be formed, but the hydrofluoric acid may erode the interface between the ohmic electrode and the resist mask, causing etching to reach unexpected areas
Solution Approach 1:
The patent applies preliminary action by forming an oxidized layer on the ohmic electrode before the wet etching process. This oxidized layer serves as a protective barrier that prevents the hydrofluoric acid from eroding the interface between the ohmic electrode and the resist mask, thereby maintaining etching precision and preventing defects in the gate-dielectric film
Solution Approach 2:
The oxidized layer acts as an intermediary substance between the hydrofluoric acid and the ohmic electrode interface. It provides chemical resistance to the hydrofluoric acid, preventing direct contact and erosion of the resist mask interface, thus ensuring precise etching boundaries
2Manufacturing precision
If the resist mask is formed on the ohmic electrode during wet etching, then the etching can be controlled, but the hydrofluoric acid may still erode the interface due to oxidation of the ohmic electrode surface
Solution Approach 1:
The patent applies preliminary anti-action by creating an oxidized layer on the ohmic electrode surface before the wet etching process. This oxidized layer provides chemical resistance against the hydrofluoric acid, counteracting the harmful erosion effect at the resist mask interface and preventing etching defects
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 effectively reduces fabrication failures in silicon carbide semiconductor devices by preventing unwanted etching and ensuring precise control over the etching process, resulting in a more reliable device production.
Implementation Method 1
removing an oxidized layer on the ohmic electrode
Data Source
AI summary
The fabrication method for a silicon carbide semiconductor device according to this disclosure includes a step of forming a dielectric film over part of a silicon carbide layer, a step of forming an ohmic electrode adjoining the dielectric film on the silicon carbide layer, a step of removing an oxidized layer on the ohmic electrode, a step of forming a mask with its opening on the side opposite to the side where the ohmic electrode is adjoining the dielectric film on the ohmic electrode having the oxidized layer removed and on the dielectric film, and a step of wet etching of a film to be etched with hydrofluoric acid with the mask formed. With the fabrication method for a silicon carbide semiconductor device described in this disclosure, it is possible to fabricate a silicon carbide semiconductor device with reduced failure.