Electrostatic Deflector Impedance Matching for High-Speed Beam Drawing
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Solution Overview
Problem
Conventional electron beam drawing apparatuses face difficulties in achieving high-speed high-voltage operation of electrostatic deflectors due to signal reflection and increased load on the deflection amplifier, which is also true for ion beam drawing apparatuses.
Innovation Solution
The charged beam drawing apparatus includes an electrostatic deflector with deflecting electrodes insulated from the ground plane and a series connection of capacitance and resistance between the electrodes and the ground plane, which suppresses signal reflection and allows for high-speed operation without increasing the load on the deflection amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the deflecting electrodes are connected directly to the coaxial cable without termination, then the device complexity is reduced, but signal reflection occurs and high-speed operation becomes difficult
Solution Approach 1:
A terminating resistance is introduced as an intermediary component between the coaxial cable and the deflecting electrodes. This resistance acts as a mediator that absorbs signal reflections, preventing them from returning to the deflection amplifier. The terminating resistance is connected to ground through a high-value resistance, creating an intermediate impedance stage that resolves the conflict between simple connection and high-speed operation.
2Reliability
If a terminating resistance with impedance equal to the coaxial cable is used, then signal reflection is suppressed, but the load on the deflection amplifier increases significantly
Solution Approach 1:
The solution applies local quality by using a high-value resistance (e.g., 10 MΩ) to connect the terminating resistance to ground. This creates a localized high-impedance path that minimizes the current flow and power consumption at the terminating resistance, while still maintaining effective signal reflection suppression. The local high-impedance connection allows the terminating resistance to function properly without imposing a heavy continuous load on the amplifier.
3Force
If high voltage is applied to the deflecting electrodes, then the deflection capability is improved, but the load on the amplifier and cable increases
Solution Approach 1:
The high-value resistance connection to ground converts what would be a harmful continuous current drain into a beneficial feature. By creating a high-impedance path, the system allows high voltage to be applied to the deflecting electrodes for strong deflection capability, while the minimal current flow through the high-value resistance prevents excessive power consumption and amplifier load. The previously harmful continuous current is transformed into a useful high-impedance isolation mechanism.
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-speed and high-voltage operation of the electrostatic deflector with reduced influence on the deflection amplifier, improving drawing speed without increasing the load on the amplifier.
Implementation Method 1
gives a potential generated by a deflection amplifier to each of the electrodes, thereby deflecting an electron beam by an electric field generated between the electrodes
Implementation Method 2
a capacity load is added to the end of the coaxial cable in terms of an equivalent circuit. Thus, a signal input from the deflection amplifier is substantially totally reflected by the deflecting electrodes
Data Source
AI summary
A charged beam drawing apparatus deflects, by an electrostatic deflector, a charged beam generated from a charged beam source, and applies the charged beam to a desired position on a sample to draw a pattern. The electrostatic deflector includes a plurality of deflecting electrodes arranged symmetrically with respect to a point around an optical axis of the charged beam, a ground external cylinder which is disposed coaxially with the optical axis and which is provided to enclose the deflecting electrodes, a resistive film provided on an inner surface of the ground external cylinder, and a conductive film provided on a surface of the resistive film. A capacitance is formed between the deflecting electrodes and the conductive film, and a resistance is formed between the ground conductor and the conductive film.