Active Target Heating in Ion Sources for Faster Beam Current Ramp
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Solution Overview
Problem
Existing ion implantation systems face productivity issues due to long wait times required to reach acceptable ion beam currents, especially when changing dopant species or starting from a cold condition, as the temperature increase is dependent solely on the plasma heating.
Innovation Solution
The system incorporates a target heater that can independently heat the target material within the arc chamber to a predetermined operating temperature, which can be higher than the temperature achieved by plasma heating alone, thereby reducing the time to reach desired operating conditions and increasing etching rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the target material is heated solely by plasma thermal emission, then the system structure remains simple, but the time to reach acceptable ion beam currents is excessively long
Solution Approach 1:
The patent combines two heating methods (plasma thermal emission and active target heater) into a dual heating system. The active target heater (resistive, inductive, or radiative) works together with plasma heating to rapidly heat the target material to temperatures above 200°C, significantly reducing the time to achieve acceptable ion beam currents while maintaining reasonable system complexity
Solution Approach 2:
The active target heater is used to pre-heat the target material to a predetermined temperature (above 200°C) before ion beam generation begins. This preliminary heating action eliminates the long wait time that would otherwise be required for plasma heating alone, allowing the system to reach operational temperature much faster
2Productivity
If the target material temperature is increased to enhance etching rates, then the etching efficiency improves, but the time to reach operating temperature increases
Solution Approach 1:
The patent merges active heating (resistive, inductive, or radiative) with plasma heating to achieve high target temperatures (>200°C) rapidly. This combination enables high etching rates while minimizing the time required to reach operating temperature, as the active heater provides immediate heating rather than relying solely on slower plasma thermal emission
3Power
If the target material is heated to higher temperatures, then the ion beam current increases, but the energy consumption increases
Solution Approach 1:
The active target heater is used to pre-heat the target material to a predetermined temperature (above 200°C) before ion beam generation begins. This preliminary heating reduces the total energy consumption because the plasma heating then requires less energy to maintain the temperature and generate the desired ion beam current, rather than having to heat from a cold state
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 approach significantly reduces the time needed to achieve acceptable ion beam currents, enhances the productivity of the ion source, and allows for higher target material temperatures, leading to increased etching reaction rates and beam currents.
Implementation Method 1
an indirectly heated cathode is positioned within the chamber volume, wherein the indirectly heated cathode is configured to ionize a source gas within the chamber volume, thereby defining a plasma having a plasma thermal emission associated therewith
Implementation Method 2
The target heater, for example, can comprise one or more of a resistive heating element, an inductive heating element, a radiative heating element such as a quartz halogen heating element, or a laser
Implementation Method 3
The target heater, for example, can comprise one or more of a resistive heating element, an inductive heating element, a radiative heating element such as a quartz halogen heating element, or a laser
Implementation Method 4
The target heater, for example, can comprise one or more of a resistive heating element, an inductive heating element, a radiative heating element such as a quartz halogen heating element, or a laser
Implementation Method 5
The target heater, for example, can comprise one or more of a resistive heating element, an inductive heating element, a radiative heating element such as a quartz halogen heating element, or a laser
Implementation Method 6
enhance etching and sputtering of a target material and provide improved productivity of the ion source
Data Source
AI summary
An arc chamber for an ion source defines a chamber volume, and a target material is disposed within the chamber volume. The target material comprises a dopant species and can be contained in a target member. An indirectly heated cathode is positioned within the chamber volume and ionizes a source gas within the chamber volume, defining a plasma having a plasma thermal emission. A target heater selectively heats the target material independently from the plasma thermal emission associated with the plasma. The target heater can be a resistive heating element, inductive heating element, halogen heating element, or a laser configured to selectively heat at least a portion of the target member. The target member can consist of a solid dopant material or can contain a liquid dopant material.