Ion Beam Line Electrostatic Bend for Uniformity
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Solution Overview
Problem
Conventional ion implantation systems face challenges in achieving uniformity of the longitudinal profile of ribbon ion beams, especially as wafer sizes increase, due to high non-uniformity upon extraction from the ion source and aberrations caused by space charge loading or beam transport optics, which affects dose uniformity during ion implantation.
Innovation Solution
A system comprising a corrector device with deceleration/acceleration elements, focusing lenses, and electrostatic bends to adjust the current density profile and reduce divergence of the ribbon ion beam, using electrode pairs that can be individually biased with electrostatic voltages to deflect and focus the ion beam, and a controller to optimize voltage application based on measured current density profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ion sources with extraction apertures are used, then ion beam can be extracted, but the beam exhibits high non-uniformity in longitudinal profile
Solution Approach 1:
The beam transport system is divided into multiple independent corrector devices, each with multiple electrode pairs that can be individually controlled. This segmentation allows localized adjustment of different portions of the ion beam to achieve uniform current density profile along the longitudinal dimension.
Solution Approach 2:
Each electrode pair in the corrector device can be independently biased with different electrostatic voltages, enabling local deflection of specific portions of the ion beam. This local control allows precise adjustment of the current density profile at different longitudinal positions.
2Productivity
If ribbon ion beam is used for large wafers, then processing efficiency is improved, but achieving uniform current density becomes more difficult
Solution Approach 1:
The corrector device employs dynamically adjustable electrostatic voltages on multiple electrode pairs, allowing real-time optimization of the ribbon ion beam's current density profile. This dynamic control enables the system to maintain uniformity even as beam parameters change during operation.
Solution Approach 2:
The system uses measured current density profiles to determine the electrostatic voltages applied to electrode pairs, creating a feedback control loop. This feedback mechanism continuously optimizes the beam uniformity based on actual measurements, ensuring consistent performance for large wafer processing.
3Manufacturing precision
If corrector optics are added to adjust charge density, then beam uniformity can be improved, but system complexity increases
Solution Approach 1:
The corrector device acts as an intermediary element in the beam transport system, using electrostatic fields from electrode pairs to mediate and adjust the charge density distribution. This intermediary approach provides precise control without requiring complex mechanical adjustments or additional optical components.
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 system achieves a substantially uniform current density profile along the longitudinal dimension of the ion beam with reduced divergence, ensuring improved dose uniformity across larger wafers and maintaining beam integrity during transport.
Implementation Method 1
at least one deceleration/acceleration element defining a deceleration/acceleration region for decelerating or accelerating the ion beam as the ion beam passes therethrough
Implementation Method 2
a focusing lens for reducing divergence of the ion beam along a transverse dimension
Implementation Method 3
an electrostatic bend disposed downstream of said deceleration/acceleration region to cause a deflection of the ion beam
Implementation Method 4
the electrode pairs are configured to be individually biasable by application of electrostatic voltages thereto for locally deflecting the ion beam along said longitudinal dimension
Data Source
AI summary
In one aspect, an ion implantation system is disclosed, which comprises a deceleration system configured to receive an ion beam and decelerate the ion beam at a deceleration ratio of at least 2, and an electrostatic bend disposed downstream of the deceleration system for causing a deflection of the ion beam. The electrostatic bend includes three tandem electrode pairs for receiving the decelerated beam, where each electrode pair has an inner and an outer electrode spaced apart to allow passage of the ion beam therethrough. Each of the electrodes of the end electrode pair is held at an electric potential less than an electric potential at which any of the electrodes of the middle electrode pair is held and the electrodes of the first electrode pair are held at a lower electric potential relative to the electrodes of the middle electrode pair.