Enhancement-Mode HEMT Layout for Flat Isolation Regions
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Solution Overview
Problem
Conventional high electron mobility transistors (HEMTs) require complex photolithographic and etching processes, leading to increased complexity and recessed isolation regions, which affect the flatness of interconnections.
Innovation Solution
An enhancement mode HEMT with a group III-V gate structure in the active region and a group III-V patterned structure in the isolation region, both on a substrate, using the same composition, to simplify the fabrication process and improve flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photolithographic and etching processes are used to define source/drain regions and isolation regions, then the HEMT can be fabricated with proper region definition, but the overall process complexity increases
Solution Approach 1:
The patent combines the definition of source/drain regions and isolation regions into a single photolithographic and etching process step. By using a unified patterned layer (such as a sacrificial layer or mask layer) that simultaneously defines both region types, the method eliminates the need for separate processing steps, thereby reducing fabrication process complexity while maintaining proper region definition precision
Solution Approach 2:
The patterned layer introduced in the patent serves multiple functions: it acts as an etch mask to define source/drain regions, simultaneously defines isolation regions, and may also serve as a sacrificial layer for subsequent processing. This multi-functional approach allows a single layer to perform what traditionally required multiple separate layers and process steps, reducing overall process complexity
2Reliability
If the isolation region is made more recessed than surrounding regions, then proper isolation between adjacent HEMTs is achieved, but the flatness of interconnection in the isolation region deteriorates
Solution Approach 1:
Instead of creating deep recesses in the vertical dimension to achieve isolation, the patent introduces a horizontal dimension solution by forming an interconnection structure that extends into the isolation region. This approach maintains the recessed isolation region for proper electrical isolation while providing a planarized interconnection path that restores flatness for subsequent processing and interconnection formation
3Manufacturing precision
If conventional fabrication processes are used, then source/drain regions and isolation regions can be defined, but the fabrication process becomes more complex and time-consuming
Solution Approach 1:
The patent merges multiple sequential photolithographic and etching steps into a single integrated process step. By using a unified patterned layer to simultaneously define source/drain regions and isolation regions in one etching operation, the method reduces the total number of process steps, thereby improving fabrication efficiency and productivity while maintaining the required region definition precision
Data Source
AI summary
A semiconductor device includes an enhancement mode high electron mobility transistor (HEMT) with an active region and an isolation region. The HEMT includes a substrate, a group III-V body layer, a group III-V barrier layer, a group III-V gate structure and a group III-V patterned structure. The group III-V body layer and the group III-V barrier layer are disposed on the substrate. The group III-V gate structure is disposed on the group III-V barrier layer within the active region. The group III-V patterned structure is disposed on the group III-V barrier layer within the isolation region. The composition of the group III-V patterned structure is the same as the composition of the group III-V gate structure.