Ion Source Gas Nozzles for Uniform Ribbon Beam Extraction
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Solution Overview
Problem
The non-uniformity of the ion beam height extracted from ion sources, such as indirectly heated cathode (IHC) ion sources, leads to non-uniform implant doses in semiconductor fabrication, requiring additional costly and complex components like lenses for correction.
Innovation Solution
The introduction of gas nozzles near the extraction aperture in the ion source chamber, which inject gas to shape the ribbon ion beam, compressing it in the height direction by reducing its height uniformly, using feedgas or inert shield gases like argon or xenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional components such as lenses are used to correct for non-uniform ion beam height, then the uniformity of ion beam height is improved, but the device complexity and cost increase
Solution Approach 1:
Gas nozzles are positioned near the extraction aperture to pre-shape the plasma and ion beam before extraction occurs. The gas flow is introduced in advance to compress the plasma region, ensuring uniform ion beam height is achieved during the extraction process itself, eliminating the need for post-extraction correction components
Solution Approach 2:
An intermediary gas (such as helium or argon) is introduced between the plasma generation region and the extraction aperture. This intermediary gas acts as a mediator to compress and shape the plasma, thereby controlling the uniformity of the extracted ion beam height without requiring additional optical components
2Manufacturing precision
If gas nozzles are introduced near the extraction aperture to shape the ion beam, then the uniformity of ion beam height is improved, but the device complexity increases
Solution Approach 1:
The gas nozzle system serves multiple functions simultaneously: it shapes the plasma region, controls ion beam height uniformity, and can be integrated with existing chamber structures. The same gas delivery mechanism that maintains plasma stability also performs the beam shaping function, reducing the need for separate dedicated components
Solution Approach 2:
By adjusting gas flow rate, pressure, and composition parameters, the plasma density distribution is modified to achieve uniform ion beam height. The gas flow parameters are optimized to compress the plasma region appropriately, allowing control of beam uniformity through parameter tuning rather than complex mechanical adjustments
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 the uniformity of the ion beam height, reducing the need for additional correction components and improving the consistency of the implant dose in ion implantation systems.
Implementation Method 1
the height of the ribbon ion beam may be reduced by injecting gas above and below the ion beam so as to compress the extracted ion beam in the height direction
Implementation Method 2
As current is passed through the filament, the filament emits thermionic electrons, which are accelerated toward the more positively charged cathode. These thermionic electrons serve to heat the cathode, in turn causing the cathode to emit electrons into the chamber
Data Source
AI summary
An ion source for extracting a ribbon ion beam with improved height uniformity is disclosed. Gas nozzles are disposed in the chamber proximate the extraction aperture. The gas that is introduced near the extraction aperture serves to shape the ribbon ion beam as it is being extracted. For example, the height of the ribbon ion beam may be reduced by injecting gas above and below the ion beam so as to compress the extracted ion beam in the height direction. In some embodiments, the feedgas is introduced near the extraction aperture. In other embodiments, a shield gas, such as an inert gas, is introduced near the extraction aperture.