SiC MOSFET Leakage Current Reduction via Post-RIE Annealing
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Solution Overview
Problem
Semiconductor devices using silicon carbide materials face issues with leakage current due to damage caused by reactive ion etching, which is not effectively suppressed by existing manufacturing processes.
Innovation Solution
Incorporating an annealing step after reactive ion etching, where the substrate is heated to a temperature not lower than 50°C, specifically between 70°C and 400°C, to mitigate the damage and reduce leakage current, and avoiding further reactive ion etching after annealing to prevent new leakage current generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reactive ion etching is performed to form interconnections, then manufacturing precision is improved, but leakage current increases due to damage in silicon carbide or gate insulating film
Solution Approach 1:
The patent converts the harmful effect of RIE-induced damage into a beneficial process by introducing annealing treatment. The annealing step repairs the damage caused by reactive ion etching, transforming the previously harmful damaged state into a restored state with reduced leakage current. This allows the manufacturing process to maintain high precision interconnection formation while eliminating the harmful leakage current effect.
Solution Approach 2:
The patent changes the physical parameter of temperature by introducing annealing at elevated temperatures. This parameter change restores the material properties of silicon carbide and gate insulating film that were degraded by RIE, thereby reducing leakage current while preserving the precision of interconnection structures.
2Object-generated harmful factors
If annealing is performed after reactive ion etching, then leakage current is suppressed, but additional manufacturing steps are required
Solution Approach 1:
The patent merges the annealing step with existing manufacturing processes or combines it with other necessary thermal processing steps. By integrating annealing into the overall manufacturing flow rather than treating it as a completely separate operation, the additional complexity is minimized while still achieving the benefit of leakage current suppression.
3Object-generated harmful factors
If reactive ion etching is avoided after annealing, then leakage current is reduced, but interconnection formation capability is limited
Solution Approach 1:
The patent performs annealing as a preliminary action before subsequent reactive ion etching steps. This preliminary annealing restores and protects the material structure, creating a more resilient substrate that can withstand subsequent RIE processing with minimal leakage current generation. This allows interconnection formation to proceed with reduced harmful effects.
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 suppresses leakage current in semiconductor devices, improving their performance by reducing unintended current flow and maintaining the integrity of formed interconnections.
Implementation Method 1
performing annealing of heating the substrate to a temperature not lower than 50° C. after the step of processing the conductor film
Implementation Method 2
heating the substrate to a temperature not lower than 50° C.
Implementation Method 3
processing the conductor film by etching the conductor film with reactive ion etching (RIE)
Data Source
AI summary
A method of manufacturing a MOSFET includes the steps of preparing a silicon carbide substrate, forming an active layer on the silicon carbide substrate, forming a gate oxide film on the active layer, forming a gate electrode on the gate oxide film, forming a source contact electrode on the active layer, and forming a source interconnection on the source contact electrode. The step of forming the source interconnection includes the steps of forming a conductor film on the source contact electrode and processing the conductor film by etching the conductor film with reactive ion etching. Then, the method of manufacturing a MOSFET further includes the step of performing annealing of heating the silicon carbide substrate to a temperature not lower than 50° C. after the step of processing the conductor film.