Insulated Semiconductor Body Bandgap Tuning for Low Off-State Leakage
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Solution Overview
Problem
Semiconductor devices, particularly those with a semiconductor body electrically insulated from the substrate, face challenges in mitigating band-to-band tunneling and the resulting floating body effect, which leads to increased off-state leakage current and reduced control over the device's off-state.
Innovation Solution
The selection of materials for the semiconductor body, source region, and drain region is coordinated such that the semiconductor body has a larger band gap than the source and drain regions, or vice versa, to prevent energetic overlap and reduce band-to-band tunneling, thereby eliminating the floating body effect and off-state leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the semiconductor body is electrically insulated from the substrate, then device integration and packing density are improved, but off-state leakage current increases due to band-to-band tunneling and floating body effect
Solution Approach 1:
The patent applies parameter changes by carefully selecting and coordinating the band gap parameters of different semiconductor materials. The semiconductor body is made from a material with a larger band gap (e.g., SiGe, InP, GaAs) compared to the source and drain regions (e.g., Si, Ge). This parameter differentiation creates an energy barrier that prevents band-to-band tunneling while maintaining electrical insulation between the semiconductor body and substrate, thereby reducing off-state leakage current by up to 1000 times without compromising integration density.
2Object-generated harmful factors
If material coordination is optimized to prevent band-to-band tunneling, then off-state leakage is reduced, but device complexity increases due to multiple material layers and interfaces
Solution Approach 1:
The patent implements local quality by assigning different material properties to different regions of the device. The semiconductor body uses a material with a larger band gap to prevent tunneling, while the source and drain regions use materials with smaller band gaps to maintain good carrier injection and extraction. This localized material optimization addresses the leakage problem in the body region without unnecessarily complicating the entire device structure, as each region's material is specifically tailored to its functional requirements.
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 significantly reduces off-state leakage current by up to 1000 times, improving the performance of insulated semiconductor devices by maintaining charge carrier mobility and controlling the device's off-state effectively.
Implementation Method 1
Band to band tunneling of charge carriers from, for example, a channel region to a drain region of a semiconductor device when the device is biased to an off-state can occur in some configurations of MOSFET devices
Data Source
AI summary
Material systems for source region, drain region, and a semiconductor body of transistor devices in which the semiconductor body is electrically insulated from an underlying substrate are selected to reduce or eliminate a band to band tunneling (“BTBT”) effect between different energetic bands of the semiconductor body and one or both of the source region and the drain region. This can be accomplished by selecting a material for the semiconductor body with a band gap that is larger than a band gap for material(s) selected for the source region and/or drain region.