In-Vacuum Dopant Vaporizer Flow Control for Cleaner Ion Implantation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ion implantation systems face challenges in using dopant materials with appreciable vapor pressure at low temperatures due to cross-contamination issues when operating at elevated temperatures, limiting the use of materials like AlI3 and AlCl3 in ion sources.
Innovation Solution
An ion source with vacuum-enclosed vaporizers and controllable valves that allow selective control of dopant vapor flow to the arc chamber, enabling operation at low temperatures and minimizing cross-contamination by rapidly switching between dopant species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the arc chamber operates at elevated temperatures exceeding 600°C, then ion generation efficiency is improved, but dopant materials with appreciable vapor pressure at low temperatures continuously evolve material into the arc chamber causing cross-contamination
Solution Approach 1:
The ion source is divided into separate functional zones: a vaporizer region for dopant material storage and a arc chamber region for ion generation. This spatial segmentation allows the vaporizer to be maintained at low temperatures while the arc chamber operates at high temperatures, preventing cross-contamination while maintaining ion generation efficiency.
Solution Approach 2:
A controlled vapor transport mechanism acts as an intermediary between the cold vaporizer and hot arc chamber. This intermediary system selectively transports dopant vapor to the arc chamber only when needed, preventing continuous evolution of material and cross-contamination while enabling efficient ion generation during operation.
2Device complexity
If the vaporizer is positioned within the ion source in continuous fluid communication with the arc chamber, then simplicity of design is improved, but temperature control of the vaporizer becomes subject to arc chamber temperature
Solution Approach 1:
The vaporizer is spatially segmented from the arc chamber and positioned in a separate thermal environment within the ion source. This segmentation allows independent temperature control of the vaporizer, enabling it to be maintained at low temperatures regardless of the high arc chamber temperature, while still providing vapor supply through controlled transport.
3Adaptability or versatility
If dopant materials with appreciable vapor pressure at very low temperatures are used, then versatility of dopant selection is improved, but continuous material evolution into the arc chamber occurs causing cross-contamination
Solution Approach 1:
A controlled vapor transport system serves as an intermediary between the vaporizer containing low-temperature dopant materials and the arc chamber. This intermediary mechanism selectively permits vapor transfer only during controlled periods, preventing continuous evolution and cross-contamination while enabling the use of versatile dopant materials with appreciable vapor pressure at low temperatures.
Solution Approach 2:
The vapor transport to the arc chamber is implemented as a periodic or pulsed process rather than continuous. This periodic action allows the vaporizer to maintain low temperatures with dopant materials of high vapor pressure, while transferring vapor to the arc chamber only during controlled intervals when needed for ion generation, preventing cross-contamination.
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
Enables efficient use of dopant materials with low vapor pressure at elevated temperatures, reducing cross-contamination and allowing fast transitions between singly- and multiply-charged ion species, thereby enhancing ion implantation precision and efficiency.
Implementation Method 1
a vaporizer configured to heat and vaporize a dopant material for use in the formation of the ions
Implementation Method 2
an arc chamber within the ion source can operate at elevated temperatures exceeding 600° C
Data Source
AI summary
An ion source for an ion implantation system has a vacuum enclosure defining a vacuum environment and an arc chamber defining an arc chamber environment. The arc chamber is positioned within the vacuum enclosure and has an arc chamber conduit in fluid communication with the arc chamber environment. A vaporizer is positioned within the vacuum enclosure and configured to selectively vaporize a dopant species to define a dopant vapor within a vaporizer environment. The vaporizer has a vaporizer conduit in fluid communication with the vaporizer environment. A valve within the vacuum enclosure is fluidly coupled to the arc chamber conduit and the vaporizer conduit. The valve is configured to selectively control a flow of the dopant vapor from the vaporizer environment to the arc chamber environment. The valve can be a solenoid valve controlled by a controller. Multiple vaporizers and valves can be provided for vaporizing multiple dopant species.