Nitride Heterojunction HHMT Structure Without Recess Etching
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Solution Overview
Problem
The development of normally-off high-hole-mobility transistors (HHMTs) faces manufacturing challenges, particularly in achieving a high yield rate suitable for mass production, due to process-related issues.
Innovation Solution
A nitride-based semiconductor device is designed with a heterojunction between two nitride-based semiconductor layers of different bandgaps, incorporating a doped region within the channel layer to deplete the two-dimensional hole gas (2DHG) region, eliminating the need for a recess etching step and enhancing the device's reliability and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a recess etching step is used to deplete the 2DHG region, then the device can achieve normally-off state, but the manufacturing complexity and process difficulty increase
Solution Approach 1:
The patent extracts the depletion function from the geometric recess structure and transfers it to the doped semiconductor layer. The doped layer is formed separately and then integrated into the channel, eliminating the need for complex recess etching while achieving the same electrical depletion effect.
Solution Approach 2:
The doped semiconductor layer is nested within the channel layer structure. The doped layer is formed and then the undoped channel material is deposited over it, creating a nested configuration where the doped region is embedded within the overall channel structure, simplifying the manufacturing process.
2Reliability
If a recess structure is formed to deplete 2DHG, then enhancement mode is achieved, but the manufacturing yield rate decreases
Solution Approach 1:
The doped semiconductor layer is formed in advance before the final channel structure is completed. This preliminary doping action allows for better process control and higher yield, as the doping can be performed using standard epitaxial growth techniques rather than requiring precise recess etching and subsequent filling.
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
The solution enables the creation of a p-channel enhancement mode semiconductor device with a high on-off ratio, good electrical properties, and improved yield rate, maintaining the continuity of the 2DHG region while ensuring a normally-off state without the complexity of recess formation.
Implementation Method 1
The second nitride-based semiconductor layer is disposed on the first nitride-based semiconductor layer and has a bandgap less than a bandgap of the first nitride-based semiconductor layer, so as to form a heterojunction therebetween with a two-dimensional hole gas (2DHG) region
Implementation Method 2
The third nitride-based semiconductor layer is doped to have a first conductivity type different than that of the second nitride-based semiconductor layer... the third nitride-based semiconductor layer can deplete a portion of the 2DHG region
Data Source
AI summary
A semiconductor device includes a first to a third nitride-based semiconductor layers, a source electrode, a drain electrode and a gate electrode. The second nitride-based semiconductor layer is disposed on the first nitride-based semiconductor layer and has a bandgap less than a bandgap of the first nitride-based semiconductor layer, so as to form a heterojunction therebetween with a two-dimensional hole gas (2DHG) region. A third nitride-based semiconductor layer is embedded in the second nitride-based semiconductor layer and spaced apart from the first nitride-based semiconductor layer. The third nitride-based semiconductor layer is doped to have a first conductivity type different than that of the second nitride-based semiconductor layer.