Correction Blanking Control Signal for Electron Beam Settling Time
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Solution Overview
Problem
The precision of measuring and inspecting semiconductor substrates using scanning electron beam systems is compromised due to sample electrification, leading to increased settling time and positional misalignment during high-speed scanning and blanking control.
Innovation Solution
A semiconductor measuring/inspecting apparatus with a correction blanking unit that applies a correction blanking control signal to correct ringing and response delay in the blanking control signal, shortening settling time and improving precision through real-time waveform correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed scanning and blanking control are implemented, then productivity is improved, but measurement precision deteriorates due to ringing and response delay in blanking control signals
Solution Approach 1:
The patent applies preliminary action by pre-correcting the blanking control signal waveform before it is applied to the blanking electrode. The correction blanking control signal is generated in advance to compensate for the anticipated ringing and response delay, allowing the electron beam to be accurately positioned even during high-speed scanning operations. This pre-correction approach eliminates the need for reactive adjustments and ensures precision is maintained at high speeds.
2Loss of time
If high-speed blanking control is implemented, then settling time is reduced, but beam positional misalignment occurs due to signal ringing
Solution Approach 1:
The patent applies preliminary anti-action by generating a correction blanking control signal that produces an effect opposite to the harmful ringing phenomenon. The correction signal is designed to counteract the expected oscillations and response delays, effectively canceling out the beam positional misalignment that would normally occur during high-speed blanking transitions. This allows settling time to be minimized without sacrificing positioning accuracy.
3Device complexity
If conventional blanking control is used, then device complexity is low, but unnecessary irradiation time increases reducing productivity
Solution Approach 1:
The patent applies parameter changes by modifying the waveform parameters of the blanking control signal. Instead of using a simple step function, the correction blanking control signal incorporates specific waveform characteristics (amplitude, duration, shape) that are optimized to reduce settling time and eliminate ringing effects. This parameter optimization allows for faster blanking transitions and reduced unnecessary irradiation time while maintaining system simplicity.
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 achieves high-speed scanning and high-speed blanking control, enhancing measurement and inspection precision by reducing unnecessary irradiation time and correcting beam positional misalignment.
Implementation Method 1
a target wafer (sample) is irradiated with an electron beam (electron ray) while carrying out scanning, and the energy of secondary electrons, etc. generated as a result thereof is detected
Implementation Method 2
a blanking control signal is applied to blanking control electrodes, thereby shutting off irradiation of the sample with the electron beam
Data Source
AI summary
Technique capable of achieving shortening of settling time, which is caused by ringing, etc. of a blanking control signal is provided. A measuring/inspecting apparatus is configured to have a main blanking unit and a correction blanking control unit as a high-speed switching control unit of an electron beam. During the period of switching of a main blanking control signal from ON to OFF, a correction blanking control signal is applied in real time in synchronization with the switching. The ringing caused by the main blanking are corrected so as to be cancelled out by that, the settling time is shortened as a result.