Transparent HEMT Shielding Layer for Stable Ohmic Contact Annealing
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face challenges in forming a good ohmic contact between source/drain electrodes and the channel layer due to high-temperature thermal processes, especially when used with transparent III-V semiconductors and substrates, leading to abnormal temperature detection and increased resistance.
Innovation Solution
A method involving the formation of a shielding layer on the dielectric and source/drain electrodes to prevent high-temperature light penetration, allowing for a normal thermal process that reduces contact resistance and forms a good ohmic contact, while also using a buffer and barrier layer structure to create a two-dimensional electron gas for conducting current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-temperature thermal process is performed on transparent III-V semiconductors and substrates, then the contact resistance can be reduced to form an ohmic contact, but the temperature sensor cannot operate normally due to light penetration, causing abnormal temperature detection and failure to form the ohmic contact
Solution Approach 1:
A shielding layer is introduced as an intermediary component between the transparent substrate and the thermal process environment. This shielding layer blocks light from penetrating through the transparent substrate during high-temperature thermal processing, preventing abnormal temperature detection by the temperature sensor while allowing the thermal process to proceed normally for forming ohmic contacts between source/drain electrodes and the channel layer
2Reliability
If the resistance between source/drain electrodes and III-V semiconductors is reduced by high-temperature thermal diffusion, then an ohmic contact is formed, but the temperature sensor fails to operate normally when transparent materials are used
Solution Approach 1:
The shielding layer serves as a mediator that enables the thermal diffusion process to operate normally by blocking light penetration. This allows the high-temperature thermal process to successfully reduce contact resistance and form ohmic contacts without causing abnormal temperature sensor operation or process failure
Solution Approach 2:
The shielding layer is formed in advance before the high-temperature thermal diffusion process. This preliminary action ensures that when the thermal process is subsequently performed, the light blocking function is already in place, preventing temperature sensor malfunction and enabling successful ohmic contact formation
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 shielding layer prevents abnormal temperature detection, enabling a successful ohmic contact formation and reduced resistance, improving the performance of HEMTs by ensuring a stable and efficient thermal process.
Implementation Method 1
forming a shielding layer conformally covering the dielectric layer and the source/drain electrodes... performing a thermal process on the source/drain electrodes... prevents high-temperature light penetration
Implementation Method 2
a high-temperature thermal process is needed to diffuse the metal and an Ohmic contact is formed to reduce the contact resistance (Rc)
Implementation Method 3
performing a thermal process on the source/drain electrodes
Implementation Method 4
forming a buffer layer on a transparent substrate... forming a barrier layer on the buffer layer... A channel region is formed in the buffer layer adjacent to the interface between the buffer layer and the barrier layer
Data Source
AI summary
A method for forming a high electron mobility transistor (HEMT) includes forming a buffer layer on a transparent substrate. The method further includes forming a barrier layer on the buffer layer. A channel region is formed in the buffer layer adjacent to the interface between the buffer layer and the barrier layer. The method further includes forming a dielectric layer on the barrier layer. The method further includes forming source/drain electrodes through the dielectric layer and the barrier layer and disposed on the buffer layer. The method further includes forming a shielding layer conformally covering the dielectric layer and the source/drain electrodes. The method further includes performing a thermal process on the source/drain electrodes.