Multi-Purpose Electrostatic Lens for Ion Implanter Beam Control
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Solution Overview
Problem
Current ion implanter systems, both high-current and medium-current, face challenges in precision and control, especially at lower energies, limiting their ability to deposit ions at smaller depths and dimensions on semiconductor wafers, which is essential for increasing component density on integrated circuits.
Innovation Solution
An electrostatic lens system comprising multiple electrodes with defined apertures and potentials that can perform various operations such as scanning, decelerating, accelerating, compressing, expanding, and parallelizing the ion beam, allowing for greater control and precision by manipulating the ion beam's energy, shape, and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-current ion implanter systems use expanded beam (ribbon beam) to maximize beam current, then beam current is increased, but manufacturing precision deteriorates
Solution Approach 1:
The system segments the beam delivery approach by using a scanning spot beam instead of a continuous ribbon beam. The spot beam is rapidly scanned across the wafer surface, dividing the implantation process into discrete positional steps that can be precisely controlled and tracked, thereby maintaining high current while improving precision.
Solution Approach 2:
The system employs dynamic scanning of the spot beam across the wafer surface. By rapidly moving the focused spot beam to different positions and scanning locations, the system maintains high beam current utilization while achieving precise spatial control over where ions are implanted, resolving the contradiction between current and precision.
2Manufacturing precision
If medium-current ion implanter systems scan spot beam across wafer, then manufacturing precision is improved, but beam current is reduced
Solution Approach 1:
The electrostatic lens system provides multi-functionality by combining spot beam scanning capability with expanded beam capability in a single system. The same lens can focus the beam for precision spot scanning or expand it for high-current ribbon beam operation, allowing the system to achieve both high precision and high current depending on the application requirements.
3Manufacturing precision
If ion beam energy is decreased to place more components on integrated circuit, then component density is increased, but beam control capability deteriorates
Solution Approach 1:
The system employs variable electrostatic potentials applied to multiple electrodes in the lens system to dynamically adjust beam parameters including energy, focus, and scanning characteristics. By changing the electrical parameters of the lens electrodes, the system maintains optimal beam control across a wide range of beam energies, enabling precise low-energy implantation for high component density while preserving ease of 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 electrostatic lens system enhances the control and precision of ion beams at lower energies, enabling more precise ion implantation and increased output of semiconductor wafers by performing multiple ion implanting operations, effectively addressing the limitations of existing systems.
Implementation Method 1
An electrostatic lens comprises an apertured entrance electrode that receives an ion beam. The apertured entrance electrode is configured to receive a first potential. An electrode having a curved surface is configured to receive the ion beam after passing through the apertured entrance electrode. The curved surface electrode is configured to receive a second potential.
Implementation Method 2
A biconvex-shaped focusing electrode is configured to receive the ion beam after passing from the curved surface electrode. The biconvex-shaped focusing electrode is configured to receive a third potential. A ground electrode is configured to receive the ion beam after passing from the biconvex-shaped focusing electrode. The ground electrode is configured to receive a fourth potential.
Data Source
AI summary
Multi-purpose electrostatic lens for an ion implanter. The electrostatic lens allows an ion implanter to scan, accelerate, decelerate, expand, compress, focus and parallelize an ion beam. This capability enables the ion implanter to function as either a high precision medium-current ion implanter or as a high-current ion implanter.