Arc Chamber and Graphite Slit Structure for Cleaner Ion Beams
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Solution Overview
Problem
In semiconductor manufacturing, generating high-energy ion beams for deeper ion implantation into wafers leads to increased arc voltage and current, causing wear and electric discharges that contaminate the ion beam and damage equipment, reducing the purity and efficiency of ion implantation processes.
Innovation Solution
An ion generator design featuring a refractory metal-lined arc chamber and a graphite slit member to minimize contamination and electric discharge damage, using a combination of refractory metals and graphite to enhance ion beam purity and reduce wear, with a configuration that includes an indirectly heated cathode and specific structural features to manage plasma generation and ion extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If arc voltage and current are increased to generate high-energy ion beams for deeper ion implantation, then ion beam energy and penetration depth are improved, but wear of the arc chamber and electric discharge between the arc chamber and extraction electrode increase, causing contamination and equipment damage
Solution Approach 1:
A magnet is introduced as an intermediary component between the arc chamber and extraction electrode. This magnet generates a magnetic field that confines electrons within the arc chamber, preventing electron drift and electric discharge toward the extraction electrode. The intermediary magnetic field thus protects the extraction electrode from contamination and damage while allowing high-energy ion beam generation to continue
Solution Approach 2:
The invention changes the physical parameter of electron confinement by introducing a magnetic field. By applying a magnetic field in the radial direction within the arc chamber, the electron motion is controlled and confined, preventing harmful electron drift. This parameter change (adding magnetic field confinement) allows the system to operate at higher arc voltages and currents without causing extraction electrode damage
2Manufacturing precision
If arc voltage and current are increased to generate multiply charged ions, then ion beam quality and energy are improved, but wear of the arc chamber increases, leading to contamination of the ion beam
Solution Approach 1:
The magnet serves as an intermediary that protects the arc chamber system by confining electrons. This prevents excessive electron bombardment on the arc chamber walls, reducing wear and material sputtering. Consequently, less contamination is introduced into the ion beam, maintaining higher ion beam purity even during high-power operation for multiply charged ion generation
Solution Approach 2:
The magnetic field creates an effective 'inert environment' for the arc chamber by confining the reactive electron population. This magnetic confinement prevents electrons from interacting with and eroding the arc chamber walls, thereby protecting the chamber material from wear and preventing contamination of the ion beam with chamber material
3Productivity
If high-energy ion beams are generated for deeper wafer implantation, then implantation depth and manufacturing capability are improved, but electric discharge between arc chamber and extraction electrode causes equipment damage and reduces operational reliability
Solution Approach 1:
The magnet is positioned as an intermediary protective element between the high-energy plasma environment of the arc chamber and the extraction electrode. By generating a magnetic field that confines electrons radially, it prevents electron-driven electric discharge that would otherwise damage the extraction electrode. This allows the system to reliably operate at high energies for deep implantation without equipment failure
Solution Approach 2:
The magnetic field acts as a preventive protective measure before electric discharge can occur. By confining electrons in advance within the arc chamber boundaries, the system prevents harmful electron drift and potential electric discharge events before they can damage the extraction electrode, thereby maintaining operational reliability during high-energy operation
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 stabilizes the generation of high-purity multiply charged ions, reducing contamination and equipment damage, thereby improving the efficiency and longevity of ion implantation processes while maintaining high-energy ion beam quality.
Implementation Method 1
a cathode which emits thermoelectrons toward the plasma generation space
Implementation Method 2
ions are generated by an ion generator provided with an indirectly heated cathode structure and an arc chamber
Data Source
AI summary
An ion generator includes an arc chamber defining a plasma generation space, and a cathode which emits thermoelectrons toward the plasma generation space. The arc chamber includes a box-shaped main body having an opening, and a slit member mounted to cover the opening and provided with a front slit. An inner surface of the main body is exposed to the plasma generation space made of a refractory metal material. The slit member includes an inner member made of graphite and an outer member made of another refractory metal material. The outer member includes an outer surface exposed to an outside of the arc chamber. The inner member includes an inner surface exposed to the plasma generation space, and an opening portion which forms the front slit extending from the inner surface of the inner member to the outer surface of the outer member.