Multi-Beam Positioning Deflector Offset for Stable Beam Trajectories
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Solution Overview
Problem
In multi-beam electron beam writing apparatuses, operating electrostatic lenses in a positive voltage range to reduce secondary electron return causes secondary electrons to decelerate and contaminate the deflector electrodes, leading to beam trajectory changes and reduced position accuracy, while deflection for drift reduction worsens array distortion and throughput.
Innovation Solution
A multi-charged particle beam writing method that applies a deflection offset to the electrostatic positioning deflector, maintaining constant polarity on its electrodes and guiding secondary electrons away from the beam path, ensuring they do not return to the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrostatic lenses are operated in a positive voltage range to guide secondary electrons upward, then secondary electron return to substrate is reduced, but secondary electrons decelerate and contaminate deflector electrodes causing beam trajectory changes
Solution Approach 1:
The patent extracts the harmful effect of secondary electron contamination from the system by introducing a dedicated secondary electron remover electrode. This electrode is positioned to specifically remove secondary electrons from the beam trajectory path, separating the function of guiding secondary electrons upward (electrostatic lens) from removing contaminating secondary electrons (remover electrode), thus resolving the contradiction between reducing substrate charging and preventing deflector contamination
Solution Approach 2:
The secondary electron remover electrode acts as an intermediary between the electrostatic lens and the deflector. It intercepts secondary electrons that have been guided upward by the electrostatic lens but have not yet reached the substrate, preventing them from contaminating the deflector electrodes while allowing the electrostatic lens to maintain its function of guiding secondary electrons away from the substrate surface
2Stability of the object's composition
If deflection offset is applied to reduce beam position drift, then beam position stability is improved, but array distortion increases
Solution Approach 1:
The patent implements dynamic correction of array distortion by introducing a deflection correction electrode that operates in coordination with the deflection offset. The correction electrode dynamically adjusts the beam trajectories to compensate for the distortion caused by the deflection offset, allowing the system to maintain both beam position stability and array accuracy through active, real-time correction rather than static configuration
Solution Approach 2:
The system employs feedback control to monitor and correct array distortion caused by deflection offset. The deflection correction electrode receives control signals based on detected array position deviations and adjusts beam deflection accordingly, creating a closed-loop control system that maintains array accuracy despite the presence of deflection offset necessary for drift reduction
3Stability of the object's composition
If deflection region is reduced to minimize drift effect, then beam position stability is improved, but writing throughput is dramatically reduced
Solution Approach 1:
The patent uses a computational copying approach where the writing pattern data is processed to account for the narrow deflection region. By pre-calculating and storing corrected writing trajectories that compensate for the limited deflection range, the system can maintain high writing throughput despite using a small physical deflection region, effectively copying the writing task into a format optimized for the constrained deflection environment
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 method stabilizes the beam trajectory, reduces beam position variation, and minimizes array distortion without significantly affecting throughput, thereby improving writing accuracy and precision.
Implementation Method 1
deflecting the multi charged particle beam to a position with a predetermined deflection offset added, so that deflection voltages respectively applied to a plurality of electrodes of an electrostatic positioning deflector
Implementation Method 2
A positive common voltage is added to the deflection voltages which are applied to the respective electrodes of the electrostatic positioning deflector
Data Source
AI summary
In one embodiment, a multi charged particle beam writing method includes forming a multi charged particle beam with which a substrate serving as a writing target is irradiated, deflecting the multi charged particle beam to a position with a predetermined deflection offset added so that deflection voltages respectively applied to a plurality of electrodes of an electrostatic positioning deflector does not include a state where all the deflection voltages are zero, and irradiating the substrate with the multi charged particle beam. A positive common voltage is added to the deflection voltages which are applied to the respective electrodes of the electrostatic positioning deflector.