Tin Dopant Sources for Ion Implantation Stability
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Solution Overview
Problem
Current Sn dopant sources for ion implantation are unstable, have low vapor pressure, and require significant heat, leading to inefficiencies and filament shortening in traditional ion implantation systems.
Innovation Solution
Development of stable Sn dopant sources with sufficient vapor pressure, such as CH3SnF3, that are capable of producing a high ion beam current, incorporating carbon and hydrogen atoms to prevent decomposition and etching, and using sub-atmospheric delivery systems for enhanced safety and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Sn dopant sources are used in ion implantation systems, then ion implantation can be performed, but the dopant sources are unstable and have low vapor pressure requiring significant heat which shortens filament lifetime
Solution Approach 1:
The patent changes the chemical composition parameters of the dopant source by introducing specific organic tin compounds with defined molecular structures containing carbon-hydrogen bonds. These structural modifications result in materials with higher vapor pressures at lower temperatures, eliminating the need for excessive heating and thereby preserving filament lifetime while maintaining dopant source stability.
Solution Approach 2:
The invention employs composite molecular structures combining tin atoms with organic groups (carbon and hydrogen atoms). This composite approach creates dopant sources that integrate the desirable properties of both metal tin (doping capability) and organic compounds (volatility and stability), resolving the contradiction between achieving sufficient vapor pressure and maintaining filament integrity.
2Quantity of substance
If significant heat is applied to increase vapor pressure of Sn dopant sources, then vapor pressure increases, but filament lifetime decreases due to degradation
Solution Approach 1:
The patent fundamentally changes the physical-chemical parameters of the dopant source by selecting organic tin compounds with molecular weights and intermolecular forces optimized for room temperature or near-room temperature vaporization. This parameter optimization achieves the required vapor pressure (10^-6 to 10^-3 Torr) without applying significant heat, thus protecting the filament from thermal degradation while maintaining adequate dopant supply.
3Power
If Sn metal is heated to evaporate and create Sn ions, then ion beam current is produced, but Sn deposits on chamber walls and filament shortening occurs
Solution Approach 1:
The invention changes the operational temperature parameter from high-temperature metal evaporation to low-temperature organic compound vaporization. The organic tin compounds vaporize at much lower temperatures, producing tin atoms that are then ionized in the plasma source. This parameter change eliminates tin deposition on chamber walls and filament degradation while maintaining sufficient ion beam current for effective ion implantation.
Solution Approach 2:
The organic groups (carbon and hydrogen atoms) act as intermediaries that facilitate the vaporization and transport of tin atoms to the ionization region. These intermediary atoms enable gentle heating and controlled vaporization, preventing direct contact between hot tin metal and the filament or chamber walls, thereby eliminating harmful deposits and degradation while still producing the required ion beam current.
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
The new Sn dopant sources provide improved ion source performance by maintaining stability at room temperature, preventing filament degradation, and ensuring efficient ion implantation with increased beam current and extended ion source lifetime.
Implementation Method 1
Electrons accelerate towards the arc chamber wall and collide with the dopant source gas molecule present in the arc chamber to generate a plasma. The plasma comprises dissociated ions, radicals, and neutral atoms and molecules of the dopant gas species.
Implementation Method 2
The ion source chamber comprises a cathode which is heated to its thermionic generation temperature to generate electrons.
Implementation Method 3
The dopant source is preferably delivered in sub atmospheric conditions to enhance the safety and reliability during tin ion implantation.
Data Source
Figure 1
Figure 2~3b
Figure 4a~5
AI summary
A novel method and system for using certain tin compounds as dopant sources for ion implantation are provided. A suitable tin-containing dopant source material is selected based on one or more certain attributes. Some of these attributes include stability at room temperature; sufficient vapor pressure to be delivered from its source supply to an ion chamber and, the ability to produce a suitable beam current for ion implantation to achieve the required implant Sn dosage. The dopant source is preferably delivered from a source supply that actuates under sub atmospheric conditions to enhance the safety and reliability during operation.