PrSi Alloy Ion Source Emitter for Stable Semiconductor Processing
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Solution Overview
Problem
Existing ion sources for semiconductor processing face challenges with rare earth metals like praseodymium, which exhibit poor wettability and rapid oxidation, leading to instability and introduction of impurities, such as with Au-based alloys, which alter semiconductor conductivity.
Innovation Solution
A binary alloy PrSi emitter is developed, where a tungsten or tantalum filament and hairpin are coated with silicon to improve wetting and stability, allowing for the generation of pure Pr and Si ions without introducing impurities, enabling fast and fine surface degradation in semiconductor processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure praseodymium is used as source material, then ion beam generation is achieved, but poor wettability and rapid oxidation occur leading to instability
Solution Approach 1:
The patent uses a binary alloy of praseodymium and silicon (PrSi) instead of pure praseodymium. The silicon component improves wettability on the emitter surface and forms a protective layer that prevents oxidation, while the praseodymium provides the desired ion beam generation. This composite material approach resolves the contradiction between achieving ion emission and preventing oxidation/poor wettability.
Solution Approach 2:
Silicon acts as an intermediary element between the emitter substrate and the praseodymium source material. It improves the wetting properties of the emitter surface, allowing better adhesion and stability of the liquid metal alloy, while also providing oxidation protection. This intermediary resolves the harmful effects of direct exposure of pure praseodymium to air and emitter surface.
2Reliability
If Au-based alloys are used to improve wettability, then emitter stability improves, but semiconductor conductivity is altered due to Au diffusion
Solution Approach 1:
The patent changes the compositional parameters of the source material from gold-based alloys to a praseodymium-silicon binary alloy. This parameter change maintains the desired wettability and emitter stability properties while eliminating the harmful diffusion and contamination issues associated with gold in semiconductor materials.
Solution Approach 2:
The patent converts the potential harm of praseodymium oxidation into a benefit by using silicon to control and manage the oxidation process. The silicon forms a protective oxide layer that actually protects the underlying praseodymium, turning the oxidation tendency into a protective mechanism while avoiding gold contamination issues.
3Reliability
If Pt or Ag are added to improve wettability, then emitter performance improves, but Pt or Ag impurities are introduced into semiconductor material
Solution Approach 1:
The patent changes the alloying element from platinum or silver to silicon. This parameter change maintains the necessary wettability and emitter stability while eliminating the introduction of Pt or Ag impurities into the semiconductor material, as silicon is either removed during processing or is less harmful to semiconductor properties.
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 PrSi alloy emitter provides stable operation, controlling beam current effectively and maintaining semiconductor material purity, allowing for quick and precise surface modification without introducing impurities, and can be reused with consistent ion beam composition.
Implementation Method 1
a tungsten or tantalum filament and hairpin are coated with silicon to improve wetting and stability
Implementation Method 2
a resistance heater or an electron beam heater may be used
Implementation Method 3
a resistance heater or an electron beam heater may be used
Implementation Method 4
Due to the high electric field strength at the emitter tip, an even smaller tip of liquid source material forms at the emitter tip and ions are emitted therefrom
Data Source
AI summary
An emitter for an ion source, such as a liquid metal alloy ion source (LMAIS). The emitter includes a binary alloy PrSi as a source material.