Dual-Layer SiN Insulator for GaN Surface Flatness
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Solution Overview
Problem
The manufacturing of semiconductor devices using nitride semiconductors faces challenges in maintaining the flatness of the surface during the formation of openings for gate electrodes, leading to increased leakage current due to high-energy plasma etching, which damages the surface and results in a non-ideal Schottky barrier.
Innovation Solution
A semiconductor device and manufacturing method involving a dual-layer insulating structure with a high chlorine concentration first SiN film and a lower chlorine concentration second SiN film, where the first SiN film with a chlorine concentration of 1×10^20 atoms/cm^3 is used to chemically react with the surface during dry etching, flattening it at an atomic level, while the second SiN film with a concentration of 1×10^19 atoms/cm^3 or less prevents excessive chlorine impurity and maintains insulating properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-energy plasma etching is used to form openings for gate electrodes, then the openings can be formed efficiently, but the surface flatness deteriorates and leakage current increases
Solution Approach 1:
A chlorine-containing SiN film is formed on the nitride semiconductor layer surface before the opening formation process. This preliminary layer acts as a protective buffer that absorbs the high-energy plasma impact during etching, preventing direct damage to the underlying nitride semiconductor layer surface, thus maintaining surface flatness while allowing efficient opening formation
Solution Approach 2:
The chlorine-containing SiN film serves as an intermediary layer between the high-energy plasma etching process and the nitride semiconductor layer. It mediates the interaction by absorbing excess energy and preventing direct harmful effects on the semiconductor surface, enabling both efficient etching and surface protection
2Manufacturing precision
If chlorine concentration in SiN film is increased to protect surface during etching, then surface flatness is maintained, but insulating properties deteriorate due to excessive chlorine impurity
Solution Approach 1:
The insulating structure is divided into two layers with different chlorine concentrations: the lower SiN layer has high chlorine concentration (1×10^20 atoms/cm³ or more) to protect the surface during etching, while the upper SiN layer has low chlorine concentration (1×10^19 atoms/cm³ or less) to provide good insulating properties. Each layer performs its specific function optimally
Solution Approach 2:
The insulating structure uses a composite of two SiN layers with different chlorine concentrations. This composite structure combines the protective function of high-chlorine SiN with the insulating function of low-chlorine SiN, achieving both surface flatness maintenance and good insulating properties simultaneously
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 effectively suppresses the decrease in surface flatness and leakage current, bringing the Schottky barrier closer to an ideal state, reducing power consumption and maintaining the insulating properties of the semiconductor device.
Implementation Method 1
a first SiN film having a concentration of chlorine (Cl) of 1×10^20 [atoms/cm3] or more... used to chemically react with the surface during dry etching, flattening it at an atomic level
Implementation Method 2
a first silicon nitride film and a second silicon nitride film are sequentially formed on the GaN cap layer using a plasma-enhanced chemical vapor deposition (PECVD) method
Implementation Method 3
forming an opening to expose the surface in the insulating layer by reactive ion etching using a fluorine-based gas
Data Source
AI summary
A semiconductor device includes a nitride semiconductor layer, an insulating layer provided on a surface of the nitride semiconductor layer, and a metal electrode in contact with the surface through an opening penetrating the insulating layer. The insulating layer includes a first SiN film having a concentration of chlorine (Cl) of 1×1020 [atoms/cm3] or more and a thickness of 30 nm or less, and a second SiN film having a concentration of chlorine (Cl) of 1×1019 [atoms/cm3] or less.