Ion Source Electromagnets for Uniform Ion Beam Current Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ion sources for ion beam etching suffer from non-uniform ion flux distribution, particularly at the periphery, which affects process uniformity and cannot be adequately compensated by varying grid transparency, leading to variations in ion beam current density and plasma density profiles due to changes in operating conditions or source and optics variations.
Innovation Solution
The use of multiple electromagnets, one at the center and one at the periphery of the discharge chamber, to independently control the plasma distribution by generating magnetic fields that adjust the ion beam current density distribution radially and azimuthally, allowing for tailored plasma shaping and improved control over the ion flux distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ion sources with single electromagnet or fixed grid transparency are used, then device structure is simple, but ion beam current density distribution is non-uniform and cannot be adjusted for different operating conditions
Solution Approach 1:
The ion source is divided into multiple independent electromagnet units (typically three) positioned at different angular locations around the discharge chamber. Each electromagnet can be independently controlled to generate magnetic fields that locally modify plasma density and ion flux distribution, enabling segmented control of the ion beam current density across different regions of the substrate.
Solution Approach 2:
The system transitions from fixed grid transparency to dynamically controllable electromagnet currents. By varying the current through each electromagnet independently, the magnetic field strength and resulting plasma confinement can be adjusted in real-time to compensate for changes in operating conditions such as RF power, gas pressure, and beam voltage, maintaining uniform ion beam current density distribution.
2Adaptability or versatility
If grid transparency is varied to compensate for plasma density profile, then ion beam uniformity improves under specific conditions, but the system cannot adapt to changes in operating conditions or source variations
Solution Approach 1:
Instead of modifying the physical structure of the ion optics (grid transparency), the system changes the operational parameters of the electromagnets. By adjusting the current through each electromagnet, the magnetic field strength changes, which dynamically modifies the plasma density distribution and ion flux without requiring physical modifications to the ion extraction optics.
Solution Approach 2:
The system enables feedback control by monitoring ion beam current density distribution and adjusting electromagnet currents accordingly. This allows automatic compensation for drifts in plasma density, changes in operating conditions, or variations in source performance, maintaining uniform ion beam distribution across varying operational states.
3Area of stationary object
If broad beam ion sources are used to cover large substrate areas, then treatment area increases, but ion current density uniformity decreases due to radial plasma density variation
Solution Approach 1:
Each electromagnet unit provides localized control of plasma density in its angular sector. By positioning multiple electromagnets around the discharge chamber and independently controlling each, the system creates locally optimized plasma regions that collectively produce a uniform ion beam current density distribution across the entire broad beam area, compensating for the natural radial density gradient in diffusion-dominated low pressure plasmas.
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 enables a broad, collimated, and uniform ion beam with adjustable ion current density distribution, enhancing process uniformity and adaptability to different operating conditions and substrate sizes, improving the control of ion beam profiles and plasma density distribution.
Implementation Method 1
a first electromagnet disposed at an outer periphery of the tubular sidewall of the discharge chamber for changing a distribution of the plasma inside the discharge space
Implementation Method 2
an antenna adapted to generate a plasma from the working gas inside the discharge space
Implementation Method 3
The antenna of the ion source, when carrying an oscillating high frequency current, induces a time-varying magnetic field inside the discharge vessel. In accordance with Faraday's law, the time-varying magnetic field induces a solenoidal, high frequency electric field that accelerates electrons in an azimuthal direction within the discharge vessel and sustains the ICP.
Data Source
AI summary
The presently disclosed ion sources include one or more electromagnets for changing the distribution of plasma within a discharge space of an ion source. At least one of the electromagnets is oriented about an outer periphery of a tubular sidewall of the ion source and changes a distribution of the plasma in a peripheral region of the discharge space.