FinFET Anti-Punch Through Structure for Dopant Migration Control
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Solution Overview
Problem
FinFET transistors face performance issues due to undesirable dopants migrating from anti-punch through regions into the channel region, affecting conductivity and transistor functionality.
Innovation Solution
A layer of dielectric material is deposited on the anti-punch through regions to capture and remove unwanted dopants like fluorine and hydrogen ions through an annealing process, reducing their concentration and preventing diffusion into the channel region, while maintaining the concentration of desired dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-punch through regions are doped to reduce short channel effects, then transistor reliability is improved, but undesirable dopants migrate into the channel region causing performance degradation
Solution Approach 1:
A dielectric material layer is introduced as an intermediary between the anti-punch through region and the channel region. This dielectric layer acts as a barrier that prevents undesirable dopant migration while allowing the anti-punch through region to maintain its doping profile for reliability improvement. The dielectric material is deposited conformally on the anti-punch through region and then selectively removed to expose the channel region.
Solution Approach 2:
The structure is segmented into distinct regions: the anti-punch through region with its doping profile, the dielectric material layer that separates it from the channel, and the channel region itself. This segmentation allows each region to be independently optimized - the anti-punch through region for reliability, the dielectric layer for dopant blocking, and the channel for performance.
2Reliability
If dopant concentration in anti-punch through regions is increased to enhance effectiveness, then drain-induced barrier lowering is inhibited, but dopant diffusion into the channel region increases
Solution Approach 1:
The dielectric material layer serves as a protective intermediary that enables higher dopant concentrations in the anti-punch through region without compromising channel region purity. By depositing the dielectric layer before final doping steps, the anti-punch through region can be heavily doped to effectively inhibit drain-induced barrier lowering, while the dielectric barrier prevents this excess dopant from diffusing into the channel.
Solution Approach 2:
The dielectric material layer is deposited in advance, before the anti-punch through region receives its full dopant concentration. This preliminary action establishes a protective barrier that will contain the subsequent dopant diffusion, allowing the anti-punch through region to be optimized for maximum effectiveness without worrying about channel contamination.
3Device complexity
If traditional anti-punch through regions are used without additional layers, then device complexity is minimized, but channel region conductivity is degraded by dopant contamination
Solution Approach 1:
A dielectric material layer is introduced as an intermediary between the anti-punch through region and the channel region. This dielectric layer acts as a barrier that prevents undesirable dopant migration while allowing the anti-punch through region to maintain its doping profile for reliability improvement. The dielectric material is deposited conformally on the anti-punch through region and then selectively removed to expose the channel region.
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 conductivity of the channel region, improves transistor performance by reducing leakage currents, and maintains the effectiveness of the anti-punch through regions in inhibiting drain-induced barrier lowering effects.
Implementation Method 1
removing a portion of the fluorine from the anti-punch through region by performing an annealing process on the layer of dielectric material
Implementation Method 2
undesirable dopants may migrate into the channel region from the anti-punch through region
Data Source
AI summary
An integrated circuit die includes a FinFET transistor. The FinFET transistor includes an anti-punch through region below a channel region. Undesirable dopants are removed from the anti-punch through region during formation of the source and drain regions. When source and drain recesses are formed, a layer of dielectric material is deposited in the recesses. An annealing process is then performed. Undesirable dopants diffuse from the anti-punch through region into the layer of dielectric material during the annealing process. The layer of dielectric material is then removed. The source and drain regions are then formed by depositing semiconductor material in the recesses.