HEMT Protection Layer for Ohmic Contact Without Spiking
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face issues with spiking phenomena due to material diffusion, leading to unwanted electrical connections and short circuits between the source, drain, and gate, which existing solutions do not fully address.
Innovation Solution
A semiconductor structure is developed with a protection layer between the source and drain structures and the dielectric layer, preventing conductive materials from diffusing during the heating process to form an ohmic contact, thereby avoiding short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the processing temperature is higher than 400° C. to form ohmic contact, then the electrical connection between source/drain and GaN is improved, but material diffusion occurs causing spiking phenomenon and short circuits
Solution Approach 1:
A diffusion barrier layer is introduced between the source/drain metal and the oxide layer to prevent material diffusion during high-temperature processing. This intermediary layer allows the heating process to proceed at temperatures above 400°C for forming good ohmic contact while blocking the diffusion path that would otherwise cause spiking phenomenon and short circuits between source/drain and gate.
Solution Approach 2:
The diffusion barrier layer is formed in advance before the high-temperature ohmic contact formation process. This preliminary action ensures that when the heating process occurs, the protective barrier is already in place to prevent material diffusion, allowing the electrical connection to be optimized without risking spiking phenomenon.
2Reliability
If existing solutions reduce spiking problem, then short circuit risk is decreased, but they are not satisfactory in all respects
Solution Approach 1:
The diffusion barrier layer serves multiple functions simultaneously: it prevents material diffusion during heating, maintains the integrity of the oxide layer, allows standard high-temperature processing to proceed, and ensures good ohmic contact formation. This multi-functional approach makes the solution adaptable to various processing conditions and device configurations, addressing the versatility deficiency of existing solutions.
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 protection layer effectively prevents diffusion of conductive materials, maintaining a stable ohmic contact and improving the process window by maintaining the fixed thickness ratio and material structure of the source and drain structures, thus reducing the occurrence of short circuits.
Implementation Method 1
a part of the source metal and the drain metal usually diffuses into the two-dimensional electron gas channel by a heating process
Implementation Method 2
the protection layer is disposed between the source structure and the dielectric layer and between the drain structure and the dielectric layer
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a substrate, a buffer layer, a barrier layer, a dielectric layer, a source structure, and a drain structure. The buffer layer is disposed on the substrate. The barrier layer is disposed on the buffer layer. The dielectric layer is disposed on the barrier layer. The passivation layer is disposed on the dielectric layer. The source structure and the drain structure are disposed on the passivation layer.