Sub-fin Doping via Backside Substrate Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor fabrication methods fail to effectively dope the sub-fin region of 3D semiconductor structures without introducing dopants into the top-fin region or damaging the fins, leading to performance issues and integration challenges.
Innovation Solution
A method involving the selective doping of sub-fin regions by removing a portion of the substrate to expose the sub-fin region, followed by implanting a dopant and performing an annealing process to activate it, thereby creating a doped sub-fin region with abrupt dopant profiles and reduced damage to the semiconductor fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping methods are used on 3D semiconductor structures, then the sub-fin region can be doped, but dopants are introduced into the top-fin region causing competing carriers and performance degradation
Solution Approach 1:
The substrate is segmented by selectively removing portions to expose only the sub-fin region, creating physically separated doping zones. This segmentation allows independent doping of the sub-fin region without affecting the top-fin region, resolving the contradiction between doping selectivity and device performance
Solution Approach 2:
The substrate material is extracted (removed) from regions above the sub-fin area, exposing the sub-fin region for targeted doping. This extraction creates a mask-free doping approach that prevents dopant introduction into the top-fin region, thereby maintaining device performance while achieving doping selectivity
2Productivity
If high energy implantation is used to dope the sub-fin region, then doping efficiency is improved, but the fins of the 3D semiconductor structure are damaged
Solution Approach 1:
The doping approach uses local quality by exposing only the sub-fin region through selective substrate removal, allowing low-energy implantation targeted at that specific area. This localized approach maintains fin integrity while achieving adequate doping efficiency in the exposed region
Solution Approach 2:
The implantation energy parameter is changed from high to low,配合 with the geometric exposure created by substrate removal. This parameter change reduces fin damage while the exposed geometry ensures dopants reach the sub-fin region effectively, balancing productivity and harm reduction
3Ease of operation
If the substrate is completely removed to expose the sub-fin region, then doping access is improved, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of completely removing the substrate, only sufficient portions are removed to expose the sub-fin region at the required depth. This partial action provides adequate doping access while minimizing the complexity and cost associated with extensive substrate removal operations
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 allows for improved performance and reduced manufacturing costs by providing active isolation of the sub-fin region, eliminating complications, and reducing dopant introduction into the active channel and adjacent devices, while enabling the creation of shallow and abrupt dopant profiles.
Implementation Method 1
a portion of a substrate is removed to expose a portion of a sub-fin region
Implementation Method 2
a dopant is implanted into the exposed portion of the sub-fin region
Implementation Method 3
an annealing process is performed to activate the dopant
Data Source
AI summary
Methods for doping a sub-fin region of a semiconductor structure include providing a semiconductor structure that comprises a substrate and a plurality of fins formed on the substrate, the plurality of fins having sub-fin regions adjacent to the substrate; removing the substrate to expose a portion of the sub-fin regions of the plurality of fins, and implanting a dopant material into the exposed portion of the sub-fin region. The method may also include performing an annealing process after the implantation such that the dopant becomes electrically active. The method may also include patterning the backside of the semiconductor structure. Devices constructed using the disclosed methods are also provided, and other embodiments are discussed.