Predicting Silicon Interstitials for Dopant Transient Enhanced Diffusion
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Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in predicting and minimizing transient enhanced diffusion (TED) of n-type dopants during pn junction formation, which leads to severe dopant profile broadening and difficulties in fabricating ultra-shallow junctions.
Innovation Solution
The method involves obtaining fundamental data for microscopic processes to build kinetic models that predict the temporal and spatial evolution of n-type dopant concentrations and electrical activities, utilizing quantum mechanics and molecular dynamics calculations to identify key reaction pathways and diffusion mechanisms of silicon interstitials and arsenic dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature thermal annealing is used to electrically activate implanted dopant impurities, then electrical activity of dopant impurities is improved, but transient enhanced diffusion causes severe dopant profile broadening
Solution Approach 1:
The patent applies preliminary action by performing low-energy ion implantation to introduce dopant impurities into the silicon substrate before thermal annealing. This preliminary doping step allows the dopants to be positioned at desired depths, and subsequent thermal annealing activates them electrically without significant diffusion, thus resolving the contradiction between achieving electrical activation and maintaining precise depth control.
Solution Approach 2:
The patent utilizes parameter changes by optimizing the thermal annealing conditions (temperature, time, atmosphere) to activate dopant impurities electrically while minimizing diffusion. By carefully controlling these parameters, the process achieves high electrical activation without severe dopant profile broadening, resolving the technical contradiction.
2Ease of manufacture
If conventional ion implantation and thermal annealing are used for pn junction fabrication, then manufacturing process is simple, but dopant profile broadening prevents fabrication of ultra-shallow junctions
Solution Approach 1:
The patent employs preliminary low-energy ion implantation to precisely position dopant impurities at the desired ultra-shallow depth before thermal annealing. This preliminary action ensures that even after annealing, the dopant profile remains sharp and precise, enabling fabrication of ultra-shallow junctions while maintaining process simplicity.
Solution Approach 2:
The patent replaces the conventional high-temperature thermal diffusion mechanism with a low-energy ion implantation mechanism followed by controlled thermal annealing. This substitution allows precise control of dopant depth and profile, enabling ultra-shallow junction fabrication while keeping the overall process simple and manufacturable.
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 the prediction and minimization of dopant TED, enhancing the electrical activity of dopant impurities and optimizing processing conditions for ultra-shallow pn junctions, thereby improving semiconductor device performance.
Implementation Method 1
During the thermal annealing, the dopant impurities often exhibit significant transient enhanced diffusion (TED)
Implementation Method 2
the thermal annealing repairs any ion-bombardment induced substrate damage while electrically activates the implanted dopant impurities
Data Source
AI summary
A method for predicting the contribution of silicon interstitials to n-type dopant transient enhanced diffusion during a pn junction formation is disclosed. Initially, fundamental data for a set of microscopic processes that can occur during one or more material processing operations are obtained. The fundamental data are then utilized to build kinetic models for a set of reactions that contribute substantially to an evolution of n-type dopant concentration and electrical activities. The kinetic models are subsequently applied to a simulator to predict temporal and spatial evolutions of concentration and electrical activity profiles of the n-type dopants.