Retarding Electrode Ion Repulsion in Charged-Particle Beam Writing
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Solution Overview
Problem
In charged-particle beam writing apparatuses, high current density on the sample surface shortens the cathode's lifetime due to evaporation at high temperatures and ion collisions with the current limiting aperture, leading to reduced writing throughput and cathode exhaustion.
Innovation Solution
Incorporating a retarding electrode between the anode and the current limiting aperture, set at a positive potential, and optionally a positive-ion capture electrode, to repel and capture positive ions generated by electron beam collisions, preventing them from reaching the cathode and extending its lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charged particle beam is heated to high temperature to achieve higher current density, then the writing throughput is improved, but the cathode material evaporates faster and the cathode tip shape changes, shortening the cathode's lifetime
Solution Approach 1:
A retarding electrode is introduced as an intermediary component between the anode and the current-limiting aperture. This electrode creates a potential barrier that prevents ions generated at the aperture from reaching the cathode, thereby protecting the cathode from ion bombardment damage while allowing the system to operate at high current densities for improved writing throughput
Solution Approach 2:
The retarding electrode applies a preliminary opposing force (electrostatic repulsion) to ions before they can reach the cathode. By creating a potential barrier in advance, the system prevents the harmful effect of ion bombardment on the cathode, allowing sustained high-temperature operation without cathode degradation
2Productivity
If the charged particle beam current density is increased to improve writing throughput, then the irradiation time is shortened, but ions generated by beam collisions with the current limiting aperture collide with the cathode, accelerating cathode exhaustion
Solution Approach 1:
The retarding electrode serves as a protective intermediary that intercepts ions generated by beam-aperture collisions. It creates an electrostatic barrier that repels positive ions away from the cathode, preventing the harmful collision damage that would otherwise accelerate cathode exhaustion during high-current-density operation
Solution Approach 2:
The system converts the harmful ion generation (a necessary byproduct of high-current operation) into a manageable condition. The retarding electrode captures and redirects ions away from the cathode, allowing the beneficial high current density operation to continue without the detrimental cathode damage that would normally result from ion bombardment
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 effectively prevents positive ions from colliding with the cathode, thereby extending its lifetime and maintaining high writing throughput without compromising electron beam propagation.
Implementation Method 1
a first electrode that is disposed between the anode and the aperture, and is set at a first electric potential of a polarity repelling a polarity of an ion generated due to collision of a charged particle beam
Implementation Method 2
When an electron beam collides with a current limiting aperture and the like, a gas is discharged and is ionized by secondary electrons, scattering electrons, etc., and the ions collide with the cathode
Data Source
AI summary
A charged-particle beam apparatus is provided with a cathode to emit charged particle beams, an anode to propagate the charged particle beams emitted from the cathode in a sample surface direction, an aperture to propagate a charged particle beam passing through an opening at a predetermined position and of a predetermined shape, among the charged particle beams passing through the anode, in the sample surface direction, and a first electrode that is disposed between the anode and the aperture, and is set at a first electric potential of a polarity repelling a polarity of an ion generated due to collision of a charged particle beam.