HSSOI MOSFET Floating Body Effect Mitigation
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Solution Overview
Problem
Hybrid surface semiconductor-on-insulator (HSSOI) devices face limitations due to the floating body effect, which hampers the optimization of power and performance parameters, particularly in controlling the voltage of the floating body in semiconductor-on-insulator (SOI) substrates.
Innovation Solution
A hybrid surface semiconductor-on-insulator (HSSOI) metal-oxide-semiconductor field effect transistor (MOSFET) is designed with a body region electrically tied to the source, featuring a semiconductor fin with vertically oriented sidewalls and a metal semiconductor alloy formed on the source and body regions, along with increased doping concentration through ion implantation to minimize the floating body effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HSSOI devices are formed on SOI substrate with floating body structure, then device integration and scaling are achieved, but floating body effect limits performance and power optimization
Solution Approach 1:
The patent extracts the body region from the traditional floating body configuration and creates a separate body contact structure. By forming a body contact region that is electrically connected to the substrate through an insulator layer, the invention removes the floating body effect while maintaining the SOI device structure, thus resolving the contradiction between integration and performance control.
Solution Approach 2:
The patent introduces an intermediary body contact structure between the body region and the substrate. This body contact region acts as a mediator that provides electrical connection to control the body potential, enabling independent voltage control of the body region while maintaining the SOI device architecture.
2Reliability
If body doping concentration is increased to minimize floating body effect, then forward voltage increases, but performance optimization requires low forward voltage
Solution Approach 1:
The patent separates the body contact function from the source/drain regions by creating a dedicated body contact region. This allows the body region to be heavily doped to minimize floating body effect without requiring the source/drain regions to accommodate the same doping level, thus maintaining low forward voltage characteristics.
Solution Approach 2:
The patent applies different doping concentrations to different regions: the body contact region is heavily doped to minimize floating body effect, while the source and drain regions maintain lower doping concentrations to preserve low forward voltage. This local differentiation resolves the contradiction between minimizing floating body effect and maintaining low forward voltage.
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 configuration effectively minimizes or eliminates the floating body effect, optimizing the performance and power characteristics of HSSOI MOSFETs by enhancing body doping while maintaining low forward voltage.
Implementation Method 1
The doping concentration of the exposed top portion of the body region may be increased by ion implantation to provide a low resistance contact to the body region
Data Source
AI summary
A portion of a top semiconductor layer of a semiconductor-on-insulator (SOI) substrate is patterned into a semiconductor fin having substantially vertical sidewalls. A portion of a body region of the semiconductor fin is exposed on a top surface of the semiconductor fin between two source regions having a doping of a conductivity type opposite to the body region of the semiconductor fin. A metal semiconductor alloy portion is formed directly on the two source regions and the top surface of the exposed body region between the two source regions. The doping concentration of the exposed top portion of the body region may be increased by ion implantation to provide a low-resistance contact to the body region, or a recombination region having a high-density of crystalline defects may be formed. A hybrid surface semiconductor-on-insulator (HSSOI) metal-oxide-semiconductor-field-effect-transistor (MOSFET) thus formed has a body region that is electrically tied to the source region.