Multi-Beam Optical Adjustment Using Multi-Height Aberration Measurement
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Solution Overview
Problem
Existing multi-beam writing apparatuses face challenges in accurately measuring and adjusting illumination system aberration, which affects positional accuracy and resolution of written patterns on semiconductor devices.
Innovation Solution
An optical system adjustment method that measures positional deviation amounts of individual beams at multiple heights, calculates a normalized position difference to determine illumination system aberration, and adjusts set values for optical components to reduce aberration, using a multi-charged particle beam apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-beam is used for writing, then throughput is significantly improved, but illumination system aberration affects positional accuracy and resolution
Solution Approach 1:
The patent performs preliminary measurement of beam positions at multiple heights before the actual writing process. By calculating the normalized position difference that represents illumination system aberration in advance, the system can pre-compensate for aberrations, ensuring high positional accuracy is maintained while utilizing multi-beam for high throughput writing
2Manufacturing precision
If illumination system aberration is not measured accurately, then adjustment is insufficient, but measurement capability is limited
Solution Approach 1:
The patent extends the measurement from a single plane to multiple heights along the optical axis. By measuring beam positions at two or more different heights and calculating the normalized position difference, the system obtains a more comprehensive characterization of illumination system aberration that cannot be achieved by single-plane measurement alone
Data Source
AI summary
A multi charged particle beam apparatus irradiates a substrate placed on a stage with a multi charged particle beam through an illumination optical system including a plurality of components, and an objective lens successively. In one embodiment, an optical system adjustment method for the multi charged particle beam apparatus includes measuring positional deviation amounts of a plurality of individual beams included in the multi charged particle beam at two or more different heights in an optical axis direction of a measurement surface or an imaging position of the multi charged particle beam, calculating a normalized position difference based on the two or more heights and the positional deviation amounts, the normalized position difference being an illumination system aberration equivalent amount of the illumination optical system, and adjusting a set value for at least one of the plurality of components using a value of the normalized position difference.