Enriched Selenium Ion Implantation via Sub-Atmospheric Delivery
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Solution Overview
Problem
Current selenium ion implantation technologies face challenges with solid sources, including poor flow control, extended start-up and cool-down times, frequent maintenance needs, and toxicity issues with Se precursor materials, leading to productivity losses and safety concerns.
Innovation Solution
The use of isotopically enriched selenium-based dopant precursors, particularly in the gas phase, with a sub-atmospheric delivery system that allows controlled flow and reduced quantities of Se material, minimizing waste and exposure risks, and extending ion source life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid selenium sources (Se metal or SeO2) are used for ion implantation, then selenium ions can be generated, but poor flow control and extended start-up/cool-down times occur
Solution Approach 1:
The patent changes the physical state parameter of selenium from solid to gas phase by using H2Se or SeO2 gas sources. This parameter change eliminates the need for vaporization heating and condensation cooling processes, thereby resolving the flow control instability and extended time requirements associated with solid sources.
Solution Approach 2:
The patent utilizes the gas phase of selenium compounds (H2Se or SeO2) instead of solid selenium sources. By maintaining selenium in the gas phase throughout the delivery system, the patent avoids the phase transition processes (heating to vaporize and cooling to condense) that cause time losses and flow control issues with solid sources.
2Productivity
If H2Se gas source is used for selenium implantation, then selenium ions can be generated, but selenium deposits form inside the ion implantation equipment
Solution Approach 1:
The patent extracts only the necessary selenium ions from the H2Se or SeO2 gas molecules through ionization, while the remaining molecular fragments are exhausted away. This prevents the formation of selenium deposits by ensuring that selenium is delivered in a controlled ionic form rather than as reactive molecular selenium that would condense and deposit on equipment surfaces.
Solution Approach 2:
The patent uses H2Se or SeO2 gas as an intermediary carrier that delivers selenium to the ion source in a controlled manner. The intermediary gas molecules are ionized to produce selenium ions, and the byproducts are safely exhausted, preventing direct deposition of selenium on equipment surfaces.
3Reliability
If SeO2 gas source is used for selenium implantation, then selenium ions can be generated, but oxygen poisoning occurs
Solution Approach 1:
The patent extracts only the selenium component from the SeO2 molecule through selective ionization processes, removing the harmful oxygen element. The oxygen is exhausted away with the unreacted gas, preventing oxygen poisoning of the ion source while still delivering the required selenium ions for implantation.
4Quantity of substance
If enriched selenium isotopes are used, then the quantity of Se material required is reduced, but the cost of dopant material increases
Solution Approach 1:
The patent changes the isotopic composition parameter of selenium from natural abundance to enriched isotopes. This parameter change increases the concentration of the desired selenium isotope in the dopant source, thereby reducing the total quantity of selenium material required to achieve the desired implantation dose, which offsets the higher cost of enriched material.
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 reduces the need for frequent maintenance, minimizes toxic material handling, and enhances productivity by allowing stable and safe selenium ion implantation with longer maintenance cycles and lower consumable costs.
Implementation Method 1
ionizing the enriched selenium-based dopant precursor material to produce ions of the specific selenium mass isotope
Implementation Method 2
the solid sources require a vaporizer assembly and sufficient heating of the solid to generate Se containing vapors with sufficient vapor pressure
Data Source
AI summary
A novel method for ion implanting isotopically enriched selenium containing source material is provided. The source material is selected and enriched in a specific mass isotope of selenium, whereby the enrichment is above natural abundance levels. The inventive method allows reduced gas consumption and reduced waste. The source material is preferably stored and delivered from a sub-atmospheric storage and delivery device to enhance safety and reliability during the selenium ion implantation process.