Conformal Solid State Doping for Source/Drain Contact Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing contact resistance in smaller CMOS and NMOS devices due to smaller contact areas poses a challenge, particularly for FinFET and nanowire devices, where traditional ion implantation methods are difficult to implement effectively.
Innovation Solution
The use of atomic layer deposition (ALD) for conformal solid state doping (SSD) to form dopant layers in source/drain regions, which includes surface cleaning, deposition of a dopant layer, a capping layer, and a drive-in anneal step to achieve precise sub-nanometer thickness control and ultra-shallow doping profiles, thereby improving contact resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ion implantation is used to achieve high source/drain doping, then contact resistance can be reduced, but the process becomes difficult to implement effectively in FinFET and nanowire devices
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical deposition process (atomic layer deposition or chemical vapor deposition) to deliver dopants to the source/drain regions. This substitution enables effective doping in three-dimensional structures like FinFETs and nanowires where ion implantation is difficult to implement, while still achieving the required doping levels to reduce contact resistance
Solution Approach 2:
The patent changes the doping method from physical ion implantation to chemical deposition, and further optimizes by using conformal deposition techniques with controlled thickness parameters. This allows precise control of dopant distribution and concentration in complex three-dimensional geometries, achieving both low contact resistance and ease of manufacture
2Manufacturing precision
If conformal solid state doping is used to achieve precise sub-nanometer thickness control, then doping precision is improved, but process complexity increases
Solution Approach 1:
The patent segments the doping process into distinct sequential steps: surface preparation/cleaning, conformal dopant layer deposition via atomic layer deposition or chemical vapor deposition, and thermal annealing for dopant activation and diffusion. This segmentation enables precise control of each step independently, achieving sub-nanometer thickness control while managing process complexity through systematic breakdown
Solution Approach 2:
The patent performs preliminary surface cleaning and preparation steps before dopant deposition to ensure optimal adhesion and uniformity. The conformal dopant layer is deposited with precise thickness control before the thermal annealing step, ensuring that the doping profile is established with the required precision before activation, thereby achieving high manufacturing precision
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 method achieves a significantly higher doping level (up to 5×10^20/cm^3) with minimal defect formation and morphology degradation, enhancing the performance of source/drain regions in CMOS and NMOS devices by providing conformal 3-D doping and precise control over dopant distribution.
Implementation Method 1
performing an atomic layer deposition of a dopant layer on the substrate
Implementation Method 2
performing a drive-in anneal step—to diffuse dopant from the dopant layer into the at least one formed source/drain region
Implementation Method 3
performing a surface cleaning on the substrate, the surface cleaning removing oxides or native oxides from the substrate
Data Source
AI summary
A method for improving source/drain performance through conformal solid state doping and its resulting device are disclosed. Specifically, the doping takes place through an atomic layer deposition of a dopant layer. Embodiments of the invention may allow for an increased doping layer, improved conformality, and reduced defect formation, in comparison to alternate doping methods, such as ion implantation or epitaxial doping.