Multiple Charged Particle Beam Apparatus Aberration Control
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Solution Overview
Problem
In multiple beam pattern writing, the increased number of beams leads to larger beam size and increased spherical aberration, which cannot be effectively corrected by existing methods, resulting in distortion and reduced precision in semiconductor manufacturing.
Innovation Solution
A multiple charged particle beam apparatus is designed with a configuration that includes a pre-shaping aperture array substrate, a shaping aperture array substrate, and grating lenses to form multiple beams, using magnetic and electric fields to control beam convergence and limit scattered electrons, thereby reducing distortion and spherical aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of beams is increased to improve throughput, then productivity is improved, but the beam size grows and spherical aberration increases
Solution Approach 1:
The patent divides the beam formation process into multiple stages using a doublet lens system with two separate lens groups. Each lens group independently controls specific aspects of beam formation, allowing the system to handle multiple beams simultaneously while maintaining precise control over beam size and aberration for each individual beam.
Solution Approach 2:
The patent employs adjustable lens drive mechanisms that allow dynamic control of the doublet lens configuration. The lens groups can be independently positioned and focused to optimize beam formation for different numbers of beams, enabling the system to maintain precision while adapting to varying throughput requirements.
2Shape
If a doublet lens is used to decrease distortion, then distortion is reduced, but spherical aberration of the crossover image increases when beam size is large
Solution Approach 1:
The doublet lens is segmented into two independent lens groups that can be controlled separately. The first lens group primarily controls distortion while the second lens group compensates for spherical aberration, allowing independent optimization of both parameters without the trade-offs inherent in a fixed doublet lens design.
Solution Approach 2:
The patent changes the operational parameters of the lens system by allowing independent adjustment of focal lengths and positions for each lens group. This enables the system to optimize the balance between distortion correction and spherical aberration control based on the specific beam configuration being used.
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 apparatus effectively suppresses distortion and corrects spherical aberration, improving beam precision and reducing the crossover diameter, enhancing the accuracy of pattern writing in semiconductor manufacturing.
Implementation Method 1
a first grating lens that constitutes a concave lens by using the first aperture array substrate as a grating
Implementation Method 2
a lens action including a magnetic field distribution in which magnetic fields generated between the first aperture array substrate and the second aperture array substrate
Implementation Method 3
an electric field distribution generated by the first grating lens
Data Source
AI summary
A multiple charged particle beam apparatus includes: a first aperture array substrate to form multiple beams; a first grating lens that constitutes a concave lens by using the first aperture array substrate as a grating; a second aperture array substrate that allows the multiple beams to pass through; and a first limiting aperture substrate arranged in a position of a convergent point of the multiple beams between the first aperture array substrate and the second aperture array substrate, wherein a first aperture array image having passed through the first shaping aperture array substrate is formed on the second aperture array substrate by a lens action including a magnetic field distribution generated between the first aperture array substrate and the second aperture array substrate and having opposite signs and same magnitude and an electric field distribution generated by the first grating lens.