III-V Gate Structure Tapering for Lower Conduction Resistance
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Solution Overview
Problem
Semiconductor devices with III-V material layers face challenges in achieving optimal electrical performance due to high conduction resistance and poor control over the channel region, particularly when the length of the bottom surface of the gate structure is greater than the upper surface, leading to inefficient electron conduction and control.
Innovation Solution
A semiconductor device design featuring a gate structure with a first portion and a second portion, where the length of the second portion is less than the first portion, and the ratio of the lengths of the surfaces is optimized between 1 and 1.6, allowing for a tapered shape that reduces conduction resistance and enhances control over the channel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the gate structure has a bottom surface length greater than the upper surface length, then the gate covers more channel region, but the conduction resistance increases and control efficiency decreases
Solution Approach 1:
The gate structure employs an asymmetric trapezoidal configuration where the upper surface length is greater than the bottom surface length (ratio of 1:0.6 to 1:0.9). This asymmetric design allows the gate to effectively cover the channel region while maintaining lower conduction resistance by reducing the gate-channel contact area at the bottom, thereby resolving the contradiction between coverage area and conduction efficiency
Solution Approach 2:
The gate structure implements local quality differentiation by having different surface lengths at the top and bottom. The wider upper surface provides sufficient gate control over the channel, while the narrower bottom surface reduces the contact area that would otherwise increase conduction resistance. This localized structural variation optimizes both coverage and electrical performance
2Stability of the object's composition
If the gate structure has a bottom surface length greater than the upper surface length, then the gate structure is more stable, but the control over the channel region becomes poor
Solution Approach 1:
The asymmetric trapezoidal gate structure with upper surface longer than bottom surface (ratio 1:0.6 to 1:0.9) provides optimal channel control by positioning the wider portion over the channel region. This asymmetric configuration ensures the gate effectively modulates the channel while the broader base provides adequate structural stability, resolving the contradiction between stability and control efficiency
Solution Approach 2:
The gate structure utilizes dimensional optimization by controlling the length ratio between upper and lower surfaces within a specific range (1:0.6 to 1:0.9). This dimensional parameter optimization allows the gate to achieve both structural stability and superior channel control by distributing the structural mass appropriately across different spatial dimensions
3Ease of manufacture
If the gate structure has equal length surfaces, then the manufacturing is simpler, but the electrical performance is not optimized
Solution Approach 1:
The invention optimizes electrical performance by changing the geometric parameters of the gate structure, specifically setting the upper surface length to be 1.1 to 1.67 times the bottom surface length. This parameter modification creates a trapezoidal configuration that enhances electrical characteristics such as reducing conduction resistance and improving gate control, while remaining compatible with standard fabrication processes
4Reliability
If the gate structure is tapered with optimized ratio, then the conduction resistance decreases, but the manufacturing precision requirements increase
Solution Approach 1:
The invention specifies a practical parameter range for the upper-to-bottom surface length ratio (1:0.6 to 1:0.9, or equivalently 1.1 to 1.67:1) that optimizes conduction resistance while remaining achievable with conventional manufacturing tolerances. This parameter optimization balances electrical performance improvement with manufacturing feasibility, avoiding excessively stringent precision requirements
Data Source
AI summary
The present disclosure provides a semiconductor device and a fabrication method thereof. The semiconductor device includes a III-V material layer and a gate structure. The gate structure includes a first portion and a second portion on the first portion. The first portion is on the III-V material layer. The first portion has a first surface and a second surface opposite to the first surface and adjacent to the III-V material layer. A length of the second surface of the first portion of the gate structure is less than a length of the first surface of the first portion of the gate structure. A length of the second portion of the gate structure is less than the length of the first portion of the gate structure.