SiC Carbon Film Sputtering with Cycle Purge for Stable Plasma
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Solution Overview
Problem
Conventional methods of manufacturing silicon carbide semiconductor devices face issues such as wafer damage and defects due to abnormal plasma discharge during sputtering, caused by foreign matter adhering to the SiC wafer during plasma ignition.
Innovation Solution
A method involving a cycle purge process is introduced, where the silicon carbide semiconductor substrate is pressurized and vented with inert gases like Ar or N2 multiple times to remove unstable foreign matter from the chamber and target, preventing its adherence to the wafer and suppressing abnormal discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sputtering is performed with plasma discharge to form a film on the SiC wafer, then film formation is achieved, but foreign matter adheres to the wafer during plasma ignition causing abnormal discharge and wafer damage
Solution Approach 1:
The patent applies preliminary action by performing a cycle purge process before the actual sputtering film formation. The cycle purge involves alternating pressurization with inert gas and evacuation multiple times to remove foreign matter from the chamber and target surface before plasma ignition, preventing foreign matter adhesion during the subsequent film formation process
Solution Approach 2:
The patent uses an inert atmosphere by introducing inert gas (such as nitrogen or argon) during the cycle purge process. This inert gas environment prevents oxidation and contamination of the SiC wafer and target surface, and the inert gas flow helps remove foreign matter from the chamber before plasma discharge begins
2Productivity
If the sputtering process is performed without cycle purge, then the manufacturing process is simpler and faster, but abnormal plasma discharge occurs due to foreign matter on the wafer
Solution Approach 1:
The patent applies periodic action through the cycle purge process, which consists of repeated cycles of pressurization with inert gas and evacuation. This periodic action occurs multiple times before the actual sputtering process, systematically removing foreign matter from the chamber and target surface, thereby ensuring stable plasma discharge without significantly extending the overall manufacturing time
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 reduces foreign matter accumulation, preventing trench sidewall chipping and improving manufacturing yield by suppressing abnormal plasma discharge during ignition.
Implementation Method 1
performing a cycle purge of the silicon carbide semiconductor substrate by alternatingly pressurizing the silicon carbide semiconductor substrate with a purge gas and venting the purge gas in a cycle purge chamber
Implementation Method 2
forming a carbon film on the surface of the silicon carbide semiconductor substrate
Implementation Method 3
forming a plurality of semiconductor regions of the first conductivity type and of a second conductivity type in the first semiconductor layer by ion implantation
Data Source
AI summary
A method of manufacturing a silicon carbide semiconductor device includes: preparing a silicon carbide semiconductor substrate including a first semiconductor layer of a first conductivity type disposed on a front surface of a starting substrate of the first conductivity type, the first semiconductor layer having a dopant concentration lower than a dopant concentration of the starting substrate; forming semiconductor regions of the first conductivity type and of a second conductivity type in the first semiconductor layer by ion implantation; forming trenches in the silicon carbide semiconductor substrate, at a front surface thereof; forming a carbon film on the front surface of the silicon carbide semiconductor substrate; performing a cycle purge of the silicon carbide semiconductor substrate by alternatingly pressurizing the silicon carbide semiconductor substrate with a purge gas and venting the purge gas in a chamber; removing the silicon carbide semiconductor substrate from the chamber; and activating the semiconductor regions formed by the ion implantation.