Ribbon Ion Beam Control via Dithering Magnetic Field
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Solution Overview
Problem
Current ion implanters using ribbon beams often suffer from non-uniform current density, leading to uneven implant doses on substrates due to fluctuations in the ion beam current, which can result in areas of higher or lower implantation within the substrate.
Innovation Solution
A multi-coil assembly is used in the ion implanter to generate a magnetic field that can be dynamically adjusted by a controller responsive to beam current measurements, allowing for dithering currents to be applied to the coils to fluctuate the magnetic field strength and correct non-uniformities in the ion beam current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a ribbon beam is used to cover the entire substrate width, then the beam width is sufficient to cover the substrate, but the beam height is much smaller than the substrate dimension, requiring substrate scanning
Solution Approach 1:
The patent applies dynamics by making the magnetic field adjustable and controllable in real-time. The coil assembly generates a magnetic field that can be dynamically modified through dithering signals, allowing the beam characteristics to be adjusted during the implantation process rather than being fixed
2Quantity of substance
If the ribbon beam current density is non-uniform, then the beam can be generated with sufficient current, but the substrate receives non-uniform implant dose
Solution Approach 1:
The patent implements feedback control by measuring the beam current and using this information to adjust the magnetic field through dithering signals. The system continuously monitors beam characteristics and modifies the magnetic field accordingly to maintain uniform current density and consistent implant dose across the substrate
Solution Approach 2:
The patent changes physical parameters by applying dithering signals that fluctuate the magnetic field strength. This dynamic parameter modification allows real-time adjustment of beam current density distribution, transforming a static non-uniform beam into a controlled uniform beam for precise implantation
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 enhances beam current dose uniformity and controls the angular spread and size of the ion beam, ensuring more consistent implantation across the substrate by real-time adjustments to the magnetic field.
Implementation Method 1
a coil assembly comprising a plurality of electromagnetic coils configured to generate a magnetic field proximate the ribbon beam, the magnetic field extending in a first direction that forms a non-zero angle with respect to a direction of propagation of the ribbon ion beam
Implementation Method 2
the at least one dithering current signal generates a fluctuation in magnetic field strength of the magnetic field
Data Source
AI summary
An apparatus to control a ribbon ion beam. The apparatus may include a coil assembly comprising a plurality of electromagnetic coils configured to generate a magnetic field proximate the ribbon beam, the magnetic field extending in a first direction that forms a non-zero angle with respect to a direction of propagation of the ribbon ion beam; a current source assembly configured to supply current to the coil assembly; and a controller configured to control the current source assembly to send at least one dithering current signal to the coil assembly responsive to a beam current measurement of the ribbon ion beam, wherein the at least one dithering current signal generates a fluctuation in magnetic field strength of the magnetic field.