Electrostatic Chuck Charge Management in SEM
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Solution Overview
Problem
Scanning electron microscopes face reduced processing capability due to charge accumulation on electrostatic chuck surfaces during semiconductor wafer measurement, which affects throughput and sensitivity, and existing charge removal methods either halt beam irradiation or reduce operation time.
Innovation Solution
A charged-particle beam device equipped with an electrometer, a charge removing device, and a control system that measures and controls the electrostatic chuck's electric potential, allowing for charge removal after a predetermined number of samples or processing time, and features a stage with varying projection densities for enhanced sensitivity and timing adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge removal is executed based on electric potential measurement, then charge effects are suppressed, but measurement and examination based on beam irradiation cannot be executed, reducing processing capability
Solution Approach 1:
The system executes charge removal operations periodically based on the number of processed samples or processing time, rather than continuously. The control device is configured to perform charge removal after a predetermined number of samples are processed or after a predetermined time period, allowing beam irradiation to continue uninterrupted while periodically eliminating charge accumulation effects
Solution Approach 2:
The electrometer continuously monitors the electric potential of the electrostatic chuck and provides feedback to the control device. Based on this feedback and the predetermined conditions (processed sample count or time), the system automatically determines when charge removal is necessary, enabling intelligent timing that balances charge suppression with continuous high-throughput measurement
2Reliability
If charge removal is executed frequently, then charge effects are minimized, but operation time is reduced and throughput decreases
Solution Approach 1:
Charge removal is performed at periodic intervals determined by either the number of samples processed or the processing time elapsed since the last charge removal. This periodic approach prevents excessive charge accumulation while minimizing interruptions to the measurement process, optimizing the balance between charge control and operational efficiency
Solution Approach 2:
The system uses multiple parameters (processed sample count and processing time) to determine charge removal timing. The control device can adjust these parameters dynamically, increasing or decreasing the processed number or processing time based on electrometer measurements that do not meet predetermined conditions, allowing flexible optimization of charge removal frequency
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 configuration enables high-throughput measurements while minimizing charge effects, ensuring high sensitivity and reducing the risk of transfer errors and wafer breakage by accurately managing charge removal timing and frequency.
Implementation Method 1
an electrometer that measures electric potential of the electrostatic chuck
Implementation Method 2
a charge removing device that removes charge from the electrostatic chuck
Implementation Method 3
an electrostatic chuck mechanism that holds a sample to be irradiated by a beam
Data Source
AI summary
A charged-particle beam device wherein suppressing the effects of static build-up is compatible with executing high-throughput measurements and examination. The charged-particle beam device equipped with an electrostatic chuck (803), includes an electrometer (11) for measuring the electric potential of the electrostatic chuck, a charge removing device (805) for removing charge from the electrostatic chuck, and a control device (806) for controlling the charge removing device in such a manner that the charge removal by the charge removing device is executed after reaching a certain number of processed samples irradiated by the charged particle beam, or after a predetermined processing time. When the result of the electric potential measurement by the electrometer does not meet a predetermined condition, the control device executes at least one among increasing and decreasing the number processed or the processing time.