MOCVD Gas Sequencing for Abrupt GaN-AlGaN Hetero Interfaces
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Solution Overview
Problem
Existing methods using MOCVD struggle to achieve an ideally abrupt hetero interface in nitride semiconductor HEMT devices, hindering the production of high-performance devices with high mobility and conductance.
Innovation Solution
A method involving specific gas supply sequences in MOCVD, including growth interrupt and pre-flow processes, to form an abrupt interface between GaN and AlGaN layers, ensuring precise control of gas flow rates and durations to enhance interface abruptness without requiring a wide band gap spacer layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spacer layer is inserted between electron transit layer and barrier layer to improve interface abruptness, then mobility and conductance are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention extracts and eliminates the spacer layer from the device structure, achieving interface abruptness through optimized gas supply sequences in MOCVD that directly form the hetero interface between electron transit layer and barrier layer without requiring an intermediate spacer layer
Solution Approach 2:
The invention changes the manufacturing parameters by optimizing gas supply sequences, growth interrupt timing, and pre-flow conditions to achieve abrupt hetero interfaces through controlled deposition processes rather than through structural modifications with spacer layers
2Ease of manufacture
If conventional MOCVD method is used to form hetero interface, then manufacturing process is simple, but interface abruptness is insufficient
Solution Approach 1:
The invention implements periodic growth interrupt and pre-flow sequences during MOCVD processing, where gas supply is periodically interrupted and pre-flow conditions are applied between layer formations to achieve abrupt compositional transitions at the hetero interface
Solution Approach 2:
The invention applies preliminary pre-flow of aluminum source gas before barrier layer formation to prepare the interface region, ensuring abrupt compositional change without requiring complex post-processing or spacer layers
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 improves the abruptness of the hetero interface, enhancing mobility and conductance in the two-dimensional electron gas layer while reducing leakage current and contact resistance, thereby producing high-performance HEMT devices without increasing electrode resistance.
Implementation Method 1
a second semiconductor layer of AlxGa1-x-yInyN on a first semiconductor layer of GaN by hetero-epitaxial growth using a MOCVD method
Implementation Method 2
a two-dimensional electron gas layer that is to be an electrically conductive layer is formed in parallel with the hetero interface by a piezoelectric effect
Data Source
AI summary
A method of manufacturing a semiconductor device, in which a second semiconductor layer of AlxGa1-x-yInyN (wherein x, y, and x+y satisfy x>0, y≧0, and x+y≦1, respectively) on a first semiconductor layer of GaN by hetero-epitaxial growth using a MOCVD method, the method including the steps of: (a) supplying N source gas and Ga source gas to form the first semiconductor layer; (b) supplying the N source gas without supplying the Ga source gas and Al source gas, after step (a); (c) supplying the N source gas and the Al source gas without supplying the Ga source gas, after step (b); and (d) supplying the N source gas, the Ga source gas and the Al source gas to form the second semiconductor layer, after step (c).