Ion Source Reactive Insert for Halogen Corrosion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ion sources, particularly indirectly heated cathode (IHC) ion sources, face a limited lifetime due to corrosion from halogen species like fluorine, leading to uncontrollable tungsten growth and electrical shorting, which disrupts smooth operation and reduces the lifespan of components.
Innovation Solution
Incorporating a refractory metal ion source chamber with a reactive insert that reacts with halogen species to reduce etching rates, altering the arc plasma chemistry and lowering ionization potential, thereby reducing tungsten erosion and redeposition, and using materials like alumina or silicon as sacrificial inserts to inhibit etching and deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If halogen species are used in the ion source, then dopant ions can be generated for semiconductor implantation, but corrosion occurs on ion source components leading to limited lifetime
Solution Approach 1:
The patent introduces a sacrificial tungsten insert that is deliberately designed to be consumed rather than protected. This disposable component absorbs the corrosive halogen species through controlled etching, preventing damage to the main ion source components (cathode, repeller, chamber walls) and extending their operational lifetime.
Solution Approach 2:
The tungsten insert acts as an intermediary component between the halogen-containing dopant precursors and the sensitive ion source components. It mediates the harmful interaction by providing a sacrificial surface that reacts with halogen species, thereby protecting the main components from corrosion.
2Strength
If tungsten is used for ion source components, then structural integrity is maintained, but uncontrollable tungsten growth occurs on electrode surfaces leading to glitching
Solution Approach 1:
The patent applies local quality by creating different tungsten surfaces with different functions: the sacrificial insert provides a controlled etching surface, while the main structural components maintain their mechanical strength. The insert is strategically positioned to receive the bulk of halogen exposure, creating a localized protection zone.
Solution Approach 2:
The sacrificial tungsten insert provides preliminary anti-action by preemptively consuming halogen species through controlled etching. This prevents the halogen from reaching and causing uncontrolled tungsten deposition on the electrode surfaces, thereby maintaining operational stability.
3Duration of action of stationary object
If reactive insert is added to reduce etching, then component lifetime is extended, but device complexity increases
Solution Approach 1:
The patent segments the ion source into functional zones: the sacrificial insert, the cathode, the repeller, and the chamber walls. This segmentation allows the insert to specifically handle halogen corrosion while other components focus on their primary functions, managing complexity through functional decomposition.
Solution Approach 2:
The insert is designed as a simple, replaceable component made from common tungsten material. Its simplicity and low cost offset the added complexity, as it can be easily replaced when consumed without requiring complex replacement mechanisms or high-precision manufacturing.
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 solution extends the operational life of ion sources by reducing tungsten erosion and redeposition, preventing electrical shorting, and maintaining stable operation by lowering plasma potential and ion energy, thus enhancing the overall performance and longevity of the ion source components.
Implementation Method 1
a reactive insert disposed within the ion source chamber. The reactive insert is interoperative with the halogen species to yield a first etch rate of the refractory metal material within the ion source chamber under a first set of operating conditions that is less than a second etch rate
Implementation Method 2
a cathode disposed within the ion source chamber and configured to emit electrons to generate an arc plasma
Implementation Method 3
emit electrons to generate an arc plasma
Data Source
AI summary
An ion source includes an ion source chamber, a cathode disposed within the ion source chamber and configured to emit electrons to generate an arc plasma, and a repeller configured to repell electrons back into the arc plasma. The ion source chamber and cathode may comprise a refractory metal. The ion source chamber further includes a gas source configured to provide a halogen species to the ion source chamber. The reactive insert is interoperative with the halogen species to yield a first etch rate of the refractory metal material within the ion source chamber under a first set of operating conditions that is less than a second etch rate of the refractory metal material within the ion source chamber under the first set of operating conditions when the reactive insert is not disposed within the ion source chamber.