Ion Source Arc Chamber Seal for Beam Uniformity
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Solution Overview
Problem
Existing ion implanters face challenges in maintaining the focus and uniformity of the ion beam as it traverses from the source to the workpiece, leading to divergence and inefficient doping of semiconductor wafers.
Innovation Solution
The implementation of a 'hot type' arc ion source with a plasma arc chamber and an elongated exit aperture, combined with an electrically insulating seal to reduce gas and plasma leakage, and a cathode system that injects ionizing electrons to create a focused ion beam, along with a beam neutralizer and deflection region to form a thin ribbon beam for uniform implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional arc ion source is used, then ion beam generation is achieved, but beam divergence occurs and uniformity is lost
Solution Approach 1:
The arc chamber body is segmented into distinct regions: a confined region for ion generation and an extraction region for beam formation. The exit aperture is elongated and positioned to create a defined extraction zone, separating ion generation from beam extraction to maintain beam focus and uniformity while preventing divergence
Solution Approach 2:
The electrically insulating seal acts as an intermediary component that seals the access opening in the arc chamber body. This seal prevents plasma and gas leakage while allowing the chamber to maintain its structural integrity and electrical isolation, thereby preserving beam uniformity and preventing divergence caused by plasma escape
2Volume of moving object
If the cathode is positioned close to the chamber wall for compact design, then space is saved, but material leakage through the access opening increases
Solution Approach 1:
The electrically insulating seal serves as an intermediary barrier that seals the access opening in the arc chamber body. This seal prevents plasma and gas leakage while allowing the chamber to maintain its structural integrity and electrical isolation, thereby preserving beam uniformity and preventing divergence caused by plasma escape
Solution Approach 2:
The seal is positioned locally at the access opening where leakage occurs, providing targeted sealing without requiring redesign of the entire chamber structure. This localized solution addresses the leakage problem while maintaining the compact overall design
3Productivity
If the filament is exposed to ion plasma for ion generation, then ion beam production is achieved, but filament life is reduced
Solution Approach 1:
The filament is extracted from direct exposure to the ion plasma environment. The cathode structure and chamber design position the filament in a protected zone where it generates electrons for ionization without being bombarded by the ion plasma, thereby extending filament life while maintaining continuous ion beam production
Solution Approach 2:
The chamber walls and cathode structure serve as intermediaries that allow the filament to function without direct plasma contact. The filament generates electrons that ionize gas in the confined region, and the chamber structure prevents direct plasma exposure to the filament, extending its operational life
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 configuration reduces beam divergence, ensures uniform ion implantation across the entire wafer surface, and extends the life of the filament by shielding it from the ion plasma, resulting in improved doping precision and efficiency.
Implementation Method 1
A cathode supported in relation to the chamber interior injects ionizing electrons into the confined region with energy for ionizing gas in the chamber interior
Implementation Method 2
An electrically insulating seal engages an outer surface of the arc chamber body to impede material from exiting the chamber interior through the access opening of the arc chamber body
Data Source
AI summary
An exemplary ion source for creating a stream of ions has a chamber body that at least partially bounds an ionization region of the arc chamber. The arc chamber body is used with a hot filament arc chamber housing that either directly or indirectly heats a cathode to sufficient temperature to cause electrons to stream through the ionization region of the arc chamber. A seals has a ceramic body having an outer wall that abuts the arc chamber body along a circumferential outer lip. The seal also has one or more radially inner channels bounded by one or more inner walls spaced inwardly from the outer wall.