FinFET Transfer Doping with Amorphous Layer Crystallization
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Solution Overview
Problem
Existing FinFET doping techniques struggle to achieve deep, uniform doping profiles without damaging the fin structures, especially at smaller feature sizes, leading to inefficiencies and surface damage during processing.
Innovation Solution
A method involving the formation of a doped amorphous layer over a fin structure, followed by a knock-on implantation process that drives dopants into the fin structure, converting the amorphous layer into crystalline material and integrating it into the fin structure, thereby eliminating the need for subsequent wet etching and reducing surface damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping techniques are used on FinFET structures, then doping can be achieved, but the doping profile is not uniform and surface damage occurs
Solution Approach 1:
A doped amorphous layer is formed over the fin structure before the knock-on implantation process. This preliminary action provides a dopant source that will be driven into the fin structure during subsequent processing, enabling uniform doping without direct ion implantation damage to the fin surface
Solution Approach 2:
The doped amorphous layer acts as an intermediary between the dopant source and the fin structure. During knock-on implantation, dopants are driven from this intermediate layer into the fin, avoiding direct exposure of the fin to harsh implantation conditions while achieving deep, uniform doping
2Productivity
If feature size is reduced to increase functional density, then production efficiency improves, but doping becomes more difficult and fin structures are more easily damaged
Solution Approach 1:
The doped amorphous layer is formed in advance with appropriate thickness and dopant concentration, allowing the fin structure to be processed at smaller dimensions without direct damage from implantation. The layer protects the fin while enabling deep dopant penetration
Solution Approach 2:
The knock-on implantation process uses lower energy ions to drive dopants from the amorphous layer into the fin structure. This parameter change in the implantation mechanism allows deep doping of scaled-down fins without causing the surface damage that would occur with conventional high-energy implantation
3Productivity
If conventional doping processes are used, then doping can be achieved, but additional processing steps such as wet etching are required
Solution Approach 1:
The doped amorphous layer is formed and then directly integrated into the fin structure through knock-on implantation, combining the doping and material integration steps into a single process flow. This eliminates the need for separate wet etching steps that would be required to remove excess dopant or damaged material in conventional approaches
Solution Approach 2:
The doped amorphous layer serves multiple functions: it provides the dopant source, protects the fin structure during processing, and becomes part of the final doped fin structure. This self-service approach eliminates the need for additional processing steps to remove or replace the doping layer
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 enables deeper, more uniform doping profiles with reduced surface damage and eliminates the need for subsequent processing steps, improving the fin-to-fin merging process and maintaining structural integrity at smaller feature sizes.
Implementation Method 1
performing a knock-on implantation process to drive a dopant from the doped amorphous layer into a portion of the fin structure
Implementation Method 2
the knock-on implantation process converts at least a portion of the amorphous silicon into crystalline silicon
Data Source
AI summary
Doping techniques for fin-like field effect transistors (FinFETs) are disclosed herein. An exemplary method includes forming a fin structure, forming a doped amorphous layer over a portion of the fin structure, and performing a knock-on implantation process to drive a dopant from the doped amorphous layer into the portion of the fin structure, thereby forming a doped feature. The doped amorphous layer includes a non-crystalline form of a material. In some implementations, the knock-on implantation process crystallizes at least a portion of the doped amorphous layer, such that the portion of the doped amorphous layer becomes a part of the fin structure. In some implementations, the doped amorphous layer includes amorphous silicon, and the knock-on implantation process crystallizes a portion of the doped amorphous silicon layer.