Nitride Semiconductor Electrode Stress Management
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Solution Overview
Problem
Conventional methods for manufacturing semiconductor devices with nitride semiconductor layers result in the formation of hillocks due to stress and thermal stress, leading to poorer reliability, increased parasitic capacitance, and degraded device characteristics.
Innovation Solution
A method involving the formation of a lower electrode layer on a nitride semiconductor surface, followed by an Al layer, heat treatment, removal of the Al layer, and subsequent formation of an upper electrode layer, which reduces stress and parasitic capacitance by eliminating hillocks and allowing for improved electrode spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier metal is formed between ohmic electrode and interconnect electrode, then excellent ohmic contacts are achieved, but hillocks appear due to stress and thermal stress
Solution Approach 1:
An Al layer is introduced as an intermediary between the lower electrode layer and upper electrode layer. This Al layer serves as a stress buffer that absorbs thermal stress during heat treatment, preventing hillock formation while maintaining excellent ohmic contact properties. The Al layer is temporarily present during manufacturing and is removed after serving its stress-buffering function.
Solution Approach 2:
The invention changes the physical and chemical parameters of the electrode structure by introducing Al with specific properties (low melting point, high thermal conductivity) that differ from the barrier metal. This parameter change allows the structure to better withstand thermal stress during heat treatment without forming hillocks.
2Ease of manufacture
If hillocks are formed due to stress and thermal stress, then electrode structure is created, but parasitic capacitances between electrodes become larger
Solution Approach 1:
The Al layer acts as a mediator that enables proper electrode structure formation while preventing the harmful effect of hillock-induced parasitic capacitance. By absorbing stress during heat treatment, the Al layer ensures electrodes remain flat and properly spaced, minimizing parasitic capacitance between adjacent electrodes.
3Device complexity
If conventional electrode formation method is used, then manufacturing process is simple, but device characteristics are degraded
Solution Approach 1:
The Al layer is formed preliminarily before the final electrode structure is complete. It performs its stress-buffering function during heat treatment and is then removed, leaving behind an optimized electrode structure with excellent characteristics. This preliminary action improves device reliability without significantly complicating the overall manufacturing process.
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 enhances the reliability and performance of semiconductor devices by reducing stress, minimizing parasitic capacitance, and enabling the creation of smaller, more reliable devices with improved characteristics.
Implementation Method 1
performing a heat treatment after the formation of the Al layer
Data Source
AI summary
A method of manufacturing a semiconductor device includes: forming a lower electrode layer in contact with a surface of a nitride semiconductor layer; forming an Al layer on the lower electrode layer; performing a heat treatment after the formation of the Al layer; removing the Al layer after the heat treatment is performed; and forming an upper electrode layer on the lower electrode layer after the removal of the Al layer.