Charged Particle Beam Imaging for Resist Pattern Charging Control
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Solution Overview
Problem
Current methods for measuring resist patterns in EUV exposure processes face challenges due to resist material shrinkage and charging issues, leading to inaccurate pattern size measurements, as the charging state varies with pattern arrangement and scanning method, making it difficult to determine the optimum scanning method and static elimination timing.
Innovation Solution
A charged particle beam system that includes a charged particle source, deflector, energy discriminator, and detector, along with a computer system to generate scan images and calculate charging amounts for each frame, enabling accurate determination of the charged state and optimizing scanning methods and static elimination techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the irradiation energy of primary electrons is reduced to minimize resist shrinkage, then shrinkage is reduced, but charging control becomes more difficult and magnification fluctuation increases
Solution Approach 1:
The patent segments the charging control process into multiple independent components: (1) scanning method optimization to suppress charging generation, (2) energy filter-based charging amount measurement, and (3) static elimination operation. This segmentation allows each component to be optimized independently and combined for overall charging control.
Solution Approach 2:
The patent implements a feedback mechanism where the energy filter continuously measures the charging amount on the resist pattern, and this measured charging amount is used to adjust the scanning method and static elimination timing. The computer system automatically determines the optimal static elimination timing based on real-time charging measurements, creating a closed-loop control system.
2Measurement precision
If static elimination operation is performed frequently to eliminate charging, then magnification fluctuation is reduced, but measurement time increases and productivity decreases
Solution Approach 1:
The patent performs preliminary action by measuring the charging amount using the energy filter before conducting the actual pattern measurement. Based on this preliminary charging measurement, the system determines the optimal static elimination timing and scanning method in advance, avoiding unnecessary static elimination operations during the measurement process.
Solution Approach 2:
The patent makes the static elimination timing dynamic rather than fixed. The computer system automatically adjusts the static elimination timing based on the actual charging amount measured by the energy filter, which varies depending on the pattern arrangement, material properties, and scanning conditions. This dynamic adjustment optimizes the balance between measurement precision and productivity.
3Reliability
If trial and error method is used to determine optimal scanning method and static elimination timing, then charging control may be achieved, but time consumption increases and automation is reduced
Solution Approach 1:
The patent implements self-service by enabling the system to automatically determine the optimal scanning method and static elimination timing without operator intervention. The computer system uses the charging amount data from the energy filter to automatically select the best scanning conditions and static elimination parameters, making the system self-optimizing.
Solution Approach 2:
The patent replaces the manual trial-and-error mechanical process with an automated computational system. The computer system processes the charging amount measurements, applies optimization algorithms, and automatically determines the optimal scanning and static elimination parameters, substituting human operator judgment with automated intelligent control.
4Difficulty of detecting and measuring
If energy filter is used to measure charging amount, then charging measurement capability is improved, but accurate calculation of charging amount over multiple frames is not achieved
Solution Approach 1:
The patent ensures continuity of useful action by continuously measuring the charging amount using the energy filter across multiple frames throughout the scanning process. The system accumulates charging amount data from each frame and performs continuous monitoring, enabling accurate calculation of the total charging amount and its temporal evolution.
Solution Approach 2:
The patent adds the time dimension to the charging amount measurement by measuring and recording the charging amount for each frame separately. This temporal dimensionality allows the system to track how charging evolves over time, determine the optimal timing for static elimination, and calculate the cumulative charging amount accurately across multiple frames.
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 allows for precise measurement of resist patterns by accurately ascertaining the charged state and optimizing scanning and static elimination methods, reducing magnification fluctuations and improving semiconductor production efficiency.
Implementation Method 1
an energy discriminator that energy-discriminates a secondary electron emitted when the primary charged particle beam reaches the sample
Implementation Method 2
a deflector that scans a primary charged particle beam emitted from the charged particle source on a sample
Data Source
AI summary
The present disclosure provides a technique enabling accurate ascertaining of a charged state of a resist pattern resulting from irradiation of a charged particle beam. The present disclosure provides a charged particle beam system provided with: a charged particle device provided with a charged particle source, deflectors for causing a primary charged particle beam emitted from the charged particle source to be scanned over a sample, an energy discriminator for performing energy discrimination for secondary electrons emitted when the primary charged particle beam has reached the sample, and a detector for detecting secondary electrons which have passed the energy discriminator; and a computer system for generating a scan image on the basis of signal amounts detected by the detector, which fluctuate during scanning of primary charged particles by the deflectors, and storing the scan image into an image storage unit. The computer system generates a scan image for each frame at the time of frame integration of the scan image, calculates an amount of static build-up in each frame on the basis of the output of the scan image of each frame, and outputs information on the amount of static build-up.