Ion Source Cathode Shield U-Shaped Lip Seal Protection
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Solution Overview
Problem
Conventional ion source cathode seals in ion implantation systems are prone to leakage due to corrosive gases, leading to reduced lifetime and increased maintenance needs.
Innovation Solution
A cathode shield with a U-shaped lip and labyrinth seal is designed to reduce gas conductance and protect the boron nitride seal from corrosive gases, preventing leakage and extending the ion source's operational life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cathode seals are used in ion sources, then the ion source can operate, but the seals are etched by corrosive gases over time leading to leakage and shortened lifetime
Solution Approach 1:
A cathode shield is introduced as an intermediary component between the corrosive gas environment and the boron nitride seal. The shield includes a U-shaped lip that extends into the gas confinement chamber and a labyrinth seal structure that creates a protective barrier, preventing direct contact between corrosive gases and the seal, thereby eliminating the etching mechanism while maintaining operational integrity
Solution Approach 2:
The cathode shield is positioned in advance to block corrosive gases from reaching the seal before damage can occur. The U-shaped lip and labyrinth structure are pre-configured to deflect and contain corrosive species away from the seal area, preventing the progressive etching that would otherwise lead to leakage and failure
2Reliability
If the cathode shield with U-shaped lip is added, then gas conductance to the seal is reduced, but the device complexity increases
Solution Approach 1:
The cathode shield serves multiple functions simultaneously: it acts as a physical barrier to corrosive gases, provides structural support for the labyrinth seal, defines the gas confinement chamber geometry, and protects the boron nitride seal from direct exposure. This multi-functionality reduces the need for additional separate protective components, thereby limiting the increase in overall device complexity
Data Source
AI summary
An ion source has an arc chamber having an arc chamber body. An electrode extends into an interior region of the arc chamber body, and a cathode shield has a body that is cylindrical having an axial hole. The axial hole is configured to pass the electrode therethrough. First and second ends of the body have respective first and second gas conductance limiters. The first gas conductance limiter extends from an outer diameter of the body and has a U-shaped lip. The second gas conductance limiter has a recess for a seal to protect the seal from corrosive gases and maintain an integrity of the seal. A gas source introduces a gas to the arc chamber body. A liner has an opening configured to pass the cathode shield therethrough, where the liner has a recess. A gap is defined between the U-shaped lip and the liner, wherein the U-shaped lip reduces a conductance of gas into the gap and the recess further reduces conductance of gas into the region.