Aluminum Arc Ion Source with Temperature Control

Solution Overview

Problem

Existing ion implanters require high-temperature refractory materials for their arc ion sources due to the extreme thermal conditions, which are costly and heavy, limiting the use of more affordable and lighter alternatives.

Innovation Solution

An arc ion source fabricated partially from aluminum with improved temperature control, using sensors and controllers to maintain the arc chamber temperature between 400°C and 550°C, allowing for the use of aluminum alloys while ensuring mechanical integrity and efficient ion beam alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If refractory materials (molybdenum, tantalum, tungsten) are used for arc ion source housing, then the source can withstand extreme thermal conditions (tens of thousands of degrees Celsius), but the cost and weight increase significantly

Engineering Contradiction:

Improvearc plasma temperature resistanceVSAvoidsource housing weight

Core Design Contradiction:

TemperatureVSWeight of stationary object

Solution Approach 1:

The patent applies local quality by using different materials for different parts of the ion source assembly. The arc chamber is made of aluminum (lightweight) while the cathode and other critical components exposed to direct plasma contact use refractory materials (molybdenum, tantalum, or tungsten). This localized application of material properties allows the housing to be lightweight while still withstanding extreme thermal conditions where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining aluminum housing with refractory material components (cathode, endcap, support structures). This composite construction allows the overall assembly to benefit from both the lightweight properties of aluminum and the high-temperature resistance of refractory materials, resolving the contradiction between weight and temperature resistance.

Inventive Principle:

Principle #40Composite materials

2Temperature

If refractory materials (molybdenum, tantalum, tungsten) are used for arc ion source housing, then the source can withstand extreme thermal conditions, but the cost increases significantly

Engineering Contradiction:

Improvearc plasma temperature resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent applies local quality by using different materials for different parts of the ion source assembly. The arc chamber is made of aluminum (lightweight) while the cathode and other critical components exposed to direct plasma contact use refractory materials (molybdenum, tantalum, or tungsten). This localized application of material properties allows the housing to be lightweight while still withstanding extreme thermal conditions where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining aluminum housing with refractory material components (cathode, endcap, support structures). This composite construction allows the overall assembly to benefit from both the lightweight properties of aluminum and the high-temperature resistance of refractory materials, resolving the contradiction between weight and temperature resistance.

Inventive Principle:

Principle #40Composite materials

3Weight of stationary object

If aluminum is used for arc ion source housing, then cost and weight are reduced, but temperature control becomes critical to maintain mechanical integrity

Engineering Contradiction:

Improvesource housing weightVSAvoidmechanical integrity at elevated temperature

Core Design Contradiction:

Weight of stationary objectVSReliability

Solution Approach 1:

The patent implements feedback control through temperature sensors (thermocouples) that monitor the aluminum arc chamber temperature and provide signals to a temperature controller. The controller adjusts heater power based on the temperature feedback to maintain the chamber within the safe operating range of 400-550°C, preventing aluminum from exceeding its mechanical property limits while allowing efficient ionization operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the operating temperature parameter of the arc chamber from the traditional high-temperature operation to a controlled range of 400-550°C. This parameter change allows the use of aluminum housing while maintaining mechanical integrity, as the aluminum remains within its safe operating temperature range where it retains adequate strength and structural properties.

Inventive Principle:

Principle #35Parameter changes

4Weight of stationary object

If aluminum is used for arc ion source housing, then cost and weight are reduced, but temperature control systems must be added to ensure mechanical properties are maintained

Engineering Contradiction:

Improvesource housing weightVSAvoidtemperature control system complexity

Core Design Contradiction:

Weight of stationary objectVSDevice complexity

Solution Approach 1:

The patent implements feedback control through temperature sensors (thermocouples) that monitor the aluminum arc chamber temperature and provide signals to a temperature controller. The controller adjusts heater power based on the temperature feedback to maintain the chamber within the safe operating range of 400-550°C, preventing aluminum from exceeding its mechanical property limits while allowing efficient ionization operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the operating temperature parameter of the arc chamber from the traditional high-temperature operation to a controlled range of 400-550°C. This parameter change allows the use of aluminum housing while maintaining mechanical integrity, as the aluminum remains within its safe operating temperature range where it retains adequate strength and structural properties.

Inventive Principle:

Principle #35Parameter changes

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 solution enables the use of aluminum for the arc ion source housing, reducing costs and weight while maintaining the necessary temperature range for effective ionization, ensuring accurate ion beam placement and operation without compromising mechanical properties.

Implementation Method 1

a temperature sensor is provided that monitors temperatures within the arc chamber and provides a signal related to sensed temperature

Methodology Applied

Scientific EffectTemperature sensing: Thermocouple

Implementation Method 2

A controller is provided that monitors sensed temperature as measured by the sensor and adjusts the temperature to maintain the sensed temperature within a range

Methodology Applied

Scientific EffectTemperature control: Heating

Implementation Method 3

an aluminum alloy arc chamber body that at least partially bounds an ionization region containing gaseous ionization material that is ionized within an arc chamber region

Methodology Applied

Scientific EffectArc ionization: Electric Arc

Data Source

PatentUS7435971B2Ion source

Publication Date: 2008.10.14 AXCELIS TECHNOLOGIES INC

AI summary

An exemplary ion source for creating a stream of ions has an aluminum alloy arc 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 temperature sensor monitors temperatures within the arc chamber and provides a signal related to sensed temperature. A controller monitors sensed temperature as measured by the sensor and adjusts the temperature to maintain the sensed temperature within a range.