Electron Beam Writing Apparatus Shield Plate and Retarding Electrode
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Solution Overview
Problem
Electron beam writing apparatuses face challenges with electron beam drift due to reflected and secondary electrons, which affect the precision of pattern writing on semiconductor devices.
Innovation Solution
An electron beam writing apparatus with an electrostatic lens and a shield plate is used, where the electrostatic lens is supplied with a negative voltage to repel reflected and secondary electrons, preventing them from entering the electron optical column and maintaining beam focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an electron beam is used to write fine patterns on semiconductor devices, then manufacturing precision is improved, but electron beam drift occurs due to reflected and secondary electrons affecting writing accuracy
Solution Approach 1:
A retarding electrode is introduced as an intermediary component between the electron beam path and the vacuum chamber wall. This electrode creates a potential barrier that selectively repels low-energy reflected and secondary electrons while allowing the high-energy primary electron beam to pass through unaffected, thus eliminating beam drift without compromising writing precision
Solution Approach 2:
The potential distribution in the electron optical path is modified by applying a negative voltage to the retarding electrode. This parameter change creates an energy barrier that discriminates between electron populations based on their kinetic energy, allowing the system to filter out harmful low-energy electrons while maintaining the integrity of the high-energy writing beam
2Ease of operation
If the electron optical column is kept open to allow beam access to the sample, then ease of operation is improved, but reflected and secondary electrons can enter the column and cause beam drift
Solution Approach 1:
The retarding electrode serves as a protective intermediary that creates an energy barrier at the entrance to the electron optical column. This barrier selectively blocks reflected and secondary electrons from entering the column while maintaining the column's open configuration for easy beam access to the sample
Solution Approach 2:
The system utilizes the energy difference between the primary electron beam and the reflected/secondary electrons to convert a harmful effect into a beneficial filtering mechanism. The low-energy electrons that would normally cause damage are repelled by the potential barrier, while the high-energy writing beam passes through enhanced in stability
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 solution effectively reduces electron beam drift, ensuring accurate and precise pattern writing by creating a potential barrier that blocks low-energy reflected and secondary electrons, maintaining beam stability and targeting accuracy.
Implementation Method 1
an electrostatic lens positioned in an axial direction of the electron beam in the electron optical column, wherein the electrostatic lens is disposed immediately above the shield plate and is being supplied with negative voltage, from a voltage supply device, constantly during writing patterns on the sample
Implementation Method 2
an electrostatic lens positioned in an axial direction of the electron beam in the electron optical column, wherein the electrostatic lens is disposed immediately above the shield plate and is being supplied with negative voltage
Data Source
AI summary
An electron beam writing apparatus comprising a XY stage that a sample is placed on, an electron optical column, an electron gun emitting an electron beam disposed in the optical column, an electrostatic lens provided with electrodes aligned in an axial direction of the electron beam disposed in the optical column, wherein a shield plate is disposed between the XY stage and the electron optical column to block reflected electrons or secondary electrons generated by irradiation to the sample with the electron beam. The electrostatic lens is disposed immediately above the shield plate to change a focal position of the electron beam. A voltage supply device applies a negative voltage constantly to the electrostatic lens.