GAA Transistor Isolation Structure for Off-State Leakage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In advanced technology nodes of semiconductor fabrication, gate-all-around field-effect transistors face issues with off-state current leakage and anti-punch through implantation regions, particularly in short-channel devices, due to band-to-band tunneling effects at heavily-doped p-n junctions.
Innovation Solution
Incorporation of a p-n junction isolation structure beneath each source/drain portion, with reduced doping concentration in the anti-punch through implantation region, and use of dielectric materials to prevent physical contact and adjust doping levels, thereby minimizing band-to-band tunneling and leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-punch through implantation regions are formed in short-channel devices, then gate control is improved, but band-to-band tunneling effects cause current leakage
Solution Approach 1:
The patent applies local quality by creating distinct doping concentration zones within the anti-punch through implantation region. A first doping concentration is used in regions adjacent to source/drain portions where high doping is needed for gate control, while a second, lower doping concentration is used in intermediate regions to minimize band-to-band tunneling and current leakage. This spatial variation in doping quality resolves the contradiction between needing strong gate control and avoiding current leakage.
2Productivity
If heavily-doped p-n junctions are used in gate-all-around transistors, then device performance is improved, but off-state current leakage increases
Solution Approach 1:
The patent changes the doping concentration parameter across different regions of the anti-punch through implantation region. By transitioning from a uniform heavy doping profile to a graded profile with varying doping concentrations, the patent maintains adequate device performance while reducing the severe band-to-band tunneling effects that occur at heavily-doped junctions, thereby reducing off-state current leakage.
3Object-generated harmful factors
If doping concentration in anti-punch through implantation region is reduced, then band-to-band tunneling is minimized, but gate control effectiveness may be compromised
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatially differentiated doping concentrations. The higher doping concentration is localized to regions where gate control is most critical (adjacent to source/drain portions), while lower doping concentrations are applied in intermediate regions where band-to-band tunneling is the primary concern. This localized approach maintains gate control effectiveness while minimizing harmful tunneling effects.
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
Significantly reduces source-to-well and drain-to-well leakage currents, enhancing the performance and reliability of gate-all-around transistors by preventing band-to-band tunneling and maintaining effective gate control.
Implementation Method 1
band-to-band tunneling effects at heavily-doped p-n junctions
Data Source
AI summary
A semiconductor structure includes a first well and a second well which has a conductivity type opposite to that of the first well; a first semiconductor device formed on the first well and including a first channel, two first source/drain portions which have a conductivity type opposite to that of the first well, and at least one first isolation feature including a first doped-semiconductor portion and a first insulating portion, a conductivity type of the first doped-semiconductor portion being the same as that of the first source/drain portions; and a second semiconductor device formed on the second well and including a second channel, two second source/drain portions which have a conductivity type opposite to that of the second well, and at least one second isolation feature including a second insulating portion disposed to separate the second well from a corresponding one of the second source/drain portions.