CNT GAA FET Source/Drain Contact With Dielectric-Embedded Doping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in fabricating field-effect transistors (FETs) using carbon nanotubes (CNTs) due to difficulties in controlling the doping profile and integrating CNTs into a CMOS-compatible process flow.
Innovation Solution
The solution involves stacking aligned CNTs on a substrate to form a fin structure, using an embedded doping scheme with dielectric layers to induce charges in the CNTs, and employing a horizontal gate-all-around process flow compatible with CMOS technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon nanotubes are used to form fin structures, then carrier mobility and electrostatic performance are improved, but difficulty in controlling doping profile and integrating into CMOS process increases
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the carbon nanotube fin structure and the metal contact. This dielectric layer contains embedded dopant regions that serve as the doping mechanism, replacing traditional direct doping of the CNT channel. The dielectric mediator enables precise doping control through standard semiconductor fabrication techniques while maintaining the integrity of the CNT channel structure.
Solution Approach 2:
The dopant regions are pre-formed within the dielectric layer before the metal contact is deposited. This preliminary doping action allows the doping profile to be established and controlled using standard photolithography and ion implantation techniques prior to final contact formation, enabling precise spatial and concentration control of the doping profile.
2Reliability
If carbon nanotubes are used to form fin structures, then electrostatic performance is improved, but device fabrication complexity increases
Solution Approach 1:
The dielectric layer serves multiple functions simultaneously: it provides electrical isolation between the metal contact and the CNT channel, contains the embedded dopant regions for carrier concentration control, and acts as a structural support for the fin configuration. This multi-functionality reduces the number of separate process steps needed compared to traditional approaches.
Solution Approach 2:
The invention changes the doping approach from direct CNT doping (which requires specialized low-temperature processes) to dielectric-embedded dopant regions that can be formed using standard high-temperature semiconductor fabrication parameters. This parameter change enables compatibility with existing CMOS manufacturing lines.
3Reliability
If embedded doping with dielectric layers is used, then carrier concentration is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention replaces mechanical/direct physical doping of the CNT channel with an electromagnetic field-based approach where dopant atoms embedded in the dielectric layer generate electric fields that induce carrier concentration in the adjacent CNT channel. This substitution enables precise control through electrical field effects rather than direct material deposition on the CNT surface.
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 enables the formation of gate-all-around FETs with improved carrier concentration and reduced contact resistance, facilitating their application in advanced technology nodes and logic circuits.
Implementation Method 1
an embedded doping scheme with dielectric layers to induce charges in the CNTs
Data Source
AI summary
In a method of forming a gate-all-around field effect transistor (GAA FET), a fin structure is formed. The fin structure includes a plurality of stacked structures each comprising a dielectric layer, a CNT over the dielectric layer, a support layer over the CNT. A sacrificial gate structure is formed over the fin structure, an isolation insulating layer is formed, a source/drain opening is formed by patterning the isolation insulating layer, the support layer is removed from each of the plurality of stacked structures in the source/drain opening, and a source/drain contact layer is formed in the source/drain opening. The source/drain contact is formed such that the source/drain contact is in direct contact with only a part of the CNT and a part of the dielectric layer is disposed between the source/drain contact and the CNT.