Monolayer Doping for Ultra-Shallow Junctions
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Solution Overview
Problem
Conventional doping techniques, such as ion implantation and solid-source diffusion, face challenges in achieving well-defined, uniformly doped ultra-shallow junctions due to dopant diffusion, crystal damage, and lack of control in nanoscale doping, particularly as semiconductor devices are scaled down.
Innovation Solution
Monolayer doping (MLD) techniques are used to form highly uniform, self-assembled, covalently bonded dopant-containing monolayers on semiconductor surfaces, allowing for precise control of dopant distribution without the need for an oxide cap, using processes like pre-amorphization implantation and thermal treatments to achieve ultra-shallow junctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ion implantation or solid-source diffusion is used for doping, then dopant atoms can be introduced into semiconductor substrate, but dopant diffusion during annealing increases the dimensions of device regions and reduces manufacturing precision
Solution Approach 1:
The patent applies preliminary action by forming a monolayer of dopant-containing organic molecules on the semiconductor surface before thermal processing. This pre-formed monolayer serves as a controlled dopant source that limits diffusion during subsequent annealing, preventing the dopant distribution width from increasing while maintaining precise doping control at the nanoscale.
Solution Approach 2:
The patent changes the physical and chemical parameters of the doping process by using organic molecules with specific thermal stability characteristics. The molecules are designed to decompose at controlled temperatures, releasing dopant atoms in a controlled manner during thermal processing. This parameter control prevents excessive dopant diffusion while enabling precise doping depth and concentration control.
2Manufacturing precision
If conventional ion implantation is used, then dopant atoms can be introduced into semiconductor, but crystal damage occurs and uniformity control is poor
Solution Approach 1:
The patent replaces the mechanical bombardment process of ion implantation with a chemical deposition process. Instead of using high-energy ion beams that mechanically impact and damage the crystal lattice, the patent uses self-assembled monolayer formation through chemical bonding, followed by controlled thermal decomposition. This substitution eliminates mechanical crystal damage while maintaining precise dopant placement and uniformity.
Solution Approach 2:
The patent introduces organic molecules as an intermediary carrier for the dopant atoms. These molecules serve as a mediator that delivers dopant atoms to the semiconductor surface in a controlled, uniform manner without causing crystal damage. The organic molecules decompose during thermal processing, releasing the dopant atoms in a controlled fashion rather than through violent implantation.
3Manufacturing precision
If monolayer doping is used to achieve atomic accuracy doping, then dopant distribution control is improved, but oxide cap layers are required to prevent dopant loss during thermal processes
Solution Approach 1:
The patent changes the thermal stability parameters of the dopant delivery system by using specially designed organic molecules that decompose at controlled temperatures. These molecules are engineered to release dopant atoms at specific temperature ranges during thermal processing, providing both dopant dose control and inherent protection against dopant loss without requiring additional oxide cap layers, thus simplifying the overall process.
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
MLD enables controlled, atomic-accuracy doping with improved uniformity and reduced dopant loss, allowing for the formation of well-defined ultra-shallow junctions without the need for oxide cap layers, enhancing the precision and reliability of semiconductor device fabrication.
Implementation Method 1
forming an amorphous region in a semiconductor substrate
Implementation Method 2
activating the implanted dopant in the amorphous region to thereby form an ultra-shallow junction
Implementation Method 3
form highly uniform, self-assembled, covalently bonded dopant-containing monolayers
Data Source
AI summary
A method of forming an ultra-shallow junction in a semiconductor substrate. The method includes forming an amorphous region in a semiconductor substrate by performing a pre-amorphization implant step and implanting one or more dopants in the amorphous region by performing a monolayer doping step. The semiconductor substrate is then thermally treated to activate the implanted dopant in the amorphous region to thereby form an ultra-shallow junction in the semiconductor substrate. The thermal treatment can be performed without any oxide cap overlying the implanted amorphous region.