III-V Semiconductor Self-Aligned Contacts
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Solution Overview
Problem
Current semiconductor technologies face challenges in achieving high electron mobility and efficient transconductance in III-V semiconductor field-effect transistors, particularly in forming reliable gate dielectric and self-aligned source-drain contacts that optimize device performance.
Innovation Solution
The method involves forming a III-V compound semiconductor heterostructure with a gate dielectric having a dielectric constant greater than 4.0 within a gate trench, accompanied by a gate conductor, and self-aligned source-drain contacts formed in relation to sidewall spacers, which are aligned with the gate conductor to ensure precise alignment and optimal contact formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gate dielectric formation methods are used, then manufacturing simplicity is maintained, but transconductance and device performance are insufficient
Solution Approach 1:
The patent changes the dielectric constant parameter by selecting materials with k>4.0 (such as HfO2, Al2O3, TiO2, or Ta2O5) to improve gate control and transconductance. This parameter change directly addresses the insufficient transconductance while maintaining compatibility with standard semiconductor fabrication processes
Solution Approach 2:
The patent employs composite material structures by combining high-k dielectric layers with specific gate conductor materials (such as tungsten, titanium nitride, or tantalum nitride). This composite approach optimizes both electrical performance and manufacturing compatibility, resolving the contradiction between improved transconductance and ease of manufacture
2Manufacturing precision
If non-self-aligned contact formation is used, then manufacturing process is simpler, but alignment precision and contact efficiency are reduced
Solution Approach 1:
The patent implements preliminary action by forming sidewall spacers on the gate structure before defining the contact regions. These spacers pre-establish the precise lateral boundaries for source and drain contacts, ensuring accurate alignment without requiring complex alignment steps during contact formation. The spacers act as self-aligned masks that guide subsequent etching or deposition processes
Solution Approach 2:
The sidewall spacers serve as self-aligned reference structures that automatically define the contact positions relative to the gate. This self-service mechanism eliminates the need for separate alignment procedures, as the contact regions are inherently positioned by the spacer geometry, thereby improving alignment precision while keeping the process relatively simple
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
This approach enhances the transconductance and power-delay product of III-V semiconductor field-effect transistors by improving the alignment and efficiency of source-drain contacts, leading to better high-speed device performance and reduced resistance.
Implementation Method 1
forming a gate dielectric having a dielectric constant greater than 4.0 positioned within a gate trench
Data Source
AI summary
A method including forming a III-V compound semiconductor-containing heterostructure, forming a gate dielectric having a dielectric constant greater than 4.0 positioned within a gate trench, the gate trench formed within the III-V compound semiconductor-containing heterostructure, and forming a gate conductor within the gate trench on top of the gate dielectric, the gate conductor extending above the III-V compound semiconductor heterostructure. The method further including forming a pair of sidewall spacers along opposite sides of a portion of the gate conductor extending above the III-V compound semiconductor-containing heterostructure and forming a pair of source-drain contacts self-aligned to the pair of sidewall spacers.