Thermal Isolation Bushing for Ion Source Gas Tube Deposition

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Solution Overview

Problem

The high temperature within ion source chambers, caused by feed gas ionization, leads to excessive heating of gas tubes, resulting in feed gas deposition and reduced system lifetime, necessitating frequent maintenance.

Innovation Solution

A thermally isolating gas bushing, made from materials like titanium, quartz, or zirconia, is placed between the ion source chamber and gas tube to reduce heat transfer, maintaining the gas tube at a lower temperature through a heat sink and allowing for symmetrical flipping to extend its life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the gas tube is directly connected to the ion source chamber, then the feed gas can be supplied efficiently, but the gas tube temperature increases excessively causing feed gas deposition

Engineering Contradiction:
Improvefeed gas supply efficiencyVSAvoidgas tube temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

A gas bushing made of thermally isolating material (such as alumina, quartz, or ceramic) is introduced as an intermediary component between the ion source chamber and the gas tube. This bushing has an inner channel that allows feed gas flow while its thermally isolating properties prevent heat transfer from the hot ion source chamber to the gas tube, thereby maintaining low gas tube temperature and preventing feed gas deposition.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the gas tube operates at high temperature, then the ionization process is maintained, but feed gas decomposes and deposits on the tube walls

Engineering Contradiction:
Improveionization process stabilityVSAvoidfeed gas deposition
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The thermally isolating gas bushing acts as a thermal barrier that decouples the temperature regimes of the ion source chamber and the gas tube. This allows the ion source chamber to maintain high temperature for effective ionization while the gas tube remains at lower temperature, preventing feed gas decomposition and deposition on tube walls.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If the gas tube is continuously used at elevated temperature, then the system operates continuously, but the gas tube lifetime is reduced

Engineering Contradiction:
Improvecontinuous operation capabilityVSAvoidgas tube lifetime
Core Design Contradiction:
ProductivityVSDuration of action of stationary object

Solution Approach 1:

By introducing the thermally isolating gas bushing, the system enables continuous operation at high productivity while protecting the gas tube from excessive temperature exposure. The bushing absorbs the thermal stress, allowing the gas tube to operate at lower temperatures and extend its service life.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The gas bushing is designed as a sacrificial or replaceable component that protects the more expensive gas tube. By making the bushing the thermal barrier, the system allows easy replacement of the bushing instead of the entire gas tube assembly, reducing maintenance costs and downtime.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 effectively reduces the gas tube's temperature by up to 200°C, minimizing feed gas deposition and extending maintenance intervals by maintaining the gas tube at a lower temperature, thus reducing maintenance frequency and prolonging operational life.

Implementation Method 1

a gas bushing, made of a thermally isolating material, is disposed between the ion source chamber and the gas tube

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

the gas tube may be in communication with a heat sink to maintain its temperature

Methodology Applied
Scientific EffectHeat sink: Heat Sink

Data Source

PatentEP3837712B1Ion source thermal gas bushing
Publication Date: 2024.03.20 VARIAN SEMICON EQUIP ASSC INC
  • EP3837712B1 patent drawingFigure 1
  • EP3837712B1 patent drawingFigure 2
  • EP3837712B1 patent drawingFigure 3

AI summary

A system for reducing clogging and deposition of feed gas on a gas tube entering an ion source chamber is disclosed. To lower the overall temperature of the gas tube, a gas bushing, made of a thermally isolating material, is disposed between the ion source chamber and the gas tube. The gas bushing is made of a thermally isolating material, such as titanium, quartz, boron nitride, zirconia or ceramic. The gas bushing has an inner channel in fluid communication with the ion source chamber and the gas tube to allow the flow of feed gas to the ion source chamber. The gas bushing may have a shape that is symmetrical, allowing it to be flipped to extend its useful life. In some embodiments, the gas tube may be in communication with a heat sink to maintain its temperature.