Tapered Recess Gate Structure for High-Frequency HEMTs
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Solution Overview
Problem
The manufacturing of high electron mobility transistors (HEMTs) with precise gate profiles is costly due to the need for machines with specific precision requirements, affecting the frequency characteristics and performance of RF devices.
Innovation Solution
A semiconductor device and fabrication method involving a substrate, channel layer, barrier layer, dielectric layer, and spacers that form a tapered recess, allowing for a gate with a smaller dimension near the barrier layer, enabling higher frequency operation without the need for high-precision photolithography machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-precision photolithography machines are used to manufacture HEMTs with precise gate profiles, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The gate structure is divided into multiple segments with different widths along its length. The gate comprises a first gate portion and a second gate portion, where the first gate portion has a greater width than the second gate portion. This segmentation allows each portion to be formed using standard photolithography processes without requiring high-precision machines, while still achieving the desired precise gate profile through the combined structure.
Solution Approach 2:
The invention transitions from controlling gate precision in a single dimension (width) to controlling it through multiple dimensions. By varying the gate width along its length (creating a tapered or stepped profile), the invention achieves precise electrical characteristics using conventional fabrication processes, thereby reducing manufacturing costs while maintaining high manufacturing precision.
2Reliability
If machines with specific precision requirements are used to manufacture HEMTs, then frequency characteristics are improved, but device complexity increases
Solution Approach 1:
The gate is segmented into multiple portions with different widths, allowing standard machines to fabricate each segment independently. This segmentation simplifies the fabrication process by eliminating the need for complex high-precision alignment procedures, thereby reducing device complexity while maintaining improved frequency characteristics through the optimized gate profile.
Solution Approach 2:
Different portions of the gate have different local qualities (widths) optimized for specific functions. The first gate portion has a greater width for stability and connection, while the second gate portion has a smaller width for enhanced frequency response. This local differentiation allows standard fabrication processes to achieve complex performance requirements without increasing overall process complexity.
Data Source
AI summary
The present disclosure provides a semiconductor device and a fabrication method thereof. The semiconductor device includes a substrate, a channel layer disposed on the substrate, and a barrier layer disposed on the channel layer. The semiconductor device further includes a dielectric layer disposed on the barrier layer and defining a first recess exposing a portion of the barrier layer. The semiconductor device further includes a first spacer disposed within the first recess, wherein the first spacer comprises a surface laterally connecting the dielectric layer to the barrier layer.