Ion Implanter Substrate Scanning with Rotation
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Solution Overview
Problem
Existing ion implantation techniques require multiple passes and complex velocity control to achieve uniform dosing, which reduces throughput and is difficult to implement effectively.
Innovation Solution
A method involving relative motion between the substrate and ion beam, combined with substrate rotation, allows the ion beam to pass over the entire substrate in a single pass, using either a ribbon or spot beam, with constant speed and rotation, forming overlapping or minimal overlap scan lines to ensure uniform implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple passes and complex velocity control are used to achieve uniform dosing, then manufacturing precision is improved, but productivity deteriorates
Solution Approach 1:
The patent segments the ion beam into multiple ribbons arranged in a two-dimensional array, allowing simultaneous implantation across the entire substrate surface rather than sequential scanning. This segmentation enables uniform dosing across all substrate areas at once, eliminating the need for multiple passes while maintaining high productivity.
Solution Approach 2:
The patent transitions from one-dimensional or two-dimensional scanning (sequential line-by-line coverage) to three-dimensional parallel illumination by arranging ion beams in a two-dimensional array that covers the entire substrate surface simultaneously. This dimensional expansion allows uniform dosing without multiple passes, resolving the contradiction between precision and productivity.
2Manufacturing precision
If multiple passes with interlacing are performed to improve uniformity, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent implements continuous uniform implantation across the entire substrate surface in a single continuous action, eliminating the intermittent stop-and-go nature of multiple passes with interlacing. All substrate areas receive ions simultaneously and continuously, achieving uniform dosing without time loss from repeated operations.
Solution Approach 2:
The patent merges multiple sequential implantation passes into a single simultaneous operation by combining multiple ion ribbons into a two-dimensional array that covers the entire substrate at once. This consolidation eliminates the time overhead associated with multiple passes while maintaining uniform dosing precision.
3Manufacturing precision
If wafer rotation is performed to address angular effects, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by ensuring each ion ribbon is uniformly distributed across its width and all ribbons in the array have identical characteristics. This local uniformity at the ribbon level, combined with the two-dimensional arrangement, achieves global uniformity across the entire substrate without requiring complex rotation or velocity control mechanisms.
Solution Approach 2:
The patent changes the spatial distribution parameter of the ion beam from a single focused spot or narrow ribbon to a two-dimensional array of multiple ribbons. This parameter change in beam geometry and arrangement achieves uniform dosing through spatial distribution rather than temporal modulation, eliminating the need for complex rotation and velocity control systems.
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 improves uniformity, increases throughput, and tolerates a larger range of ion beam profiles, reducing the need for multiple passes and complex velocity control, while maintaining high uniformity of ion implantation across the substrate.
Implementation Method 1
Ion implanters are well known and generally conform to a common design as follows. An ion source produces a mixed beam of ions from a precursor gas or the like. Only ions of a particular species are usually required for implantation in a substrate
Data Source
AI summary
This invention relates to a method of scanning a substrate through an ion beam in an ion implanter to provide uniform dosing of the substrate. The method comprises causing relative motion between the substrate and the ion beam such that the ion beam passes over all of the substrate and rotating the substrate substantially about its centre while causing the relative motion. Rotating the substrate while causing the relative motion between the substrate and the ion beam has several advantages including avoiding problematic angular effects, increasing uniformity, increasing throughput and allowing a greater range of ion beam profiles to be tolerated.