Ion Beam Etching Shutter Control for Substrate Potential Stability
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Solution Overview
Problem
Ion beam etching processes often result in fluctuations in substrate potential, leading to electrostatic damage (ESD) during the fabrication of semiconductor elements with insulating films, particularly those with narrow line widths, due to imbalances in the ion beam and electron neutralization, which existing techniques struggle to adequately address.
Innovation Solution
An ion beam etching method and apparatus that control the ion beam and electron neutralization by keeping the ion beam constant and gradually decreasing then increasing the electron emission as the shutter moves from a closed to an open position, ensuring a stable substrate potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the shutter opens to allow ion beam to reach the substrate, then etching process can proceed, but substrate potential fluctuates causing electrostatic damage
Solution Approach 1:
The system performs preliminary action by adjusting the electron beam emission intensity before the shutter opens. The control unit increases electron beam intensity in advance to compensate for the upcoming ion beam influx, preventing substrate potential fluctuation before it occurs. This proactive adjustment ensures that when the shutter opens, the electron neutralization is already optimized to counterbalance the ion beam effect.
Solution Approach 2:
The system implements feedback control by continuously monitoring substrate potential and dynamically adjusting electron beam emission intensity based on real-time conditions. When the shutter opens, the control unit detects changes in substrate potential and modulates electron beam intensity accordingly to maintain potential stability. This closed-loop feedback mechanism ensures that substrate potential remains stable throughout the etching process despite shutter operations.
2Object-affected harmful factors
If electron beam intensity is increased to neutralize substrate potential, then electrostatic damage is prevented, but control complexity increases during shutter operation
Solution Approach 1:
The system applies dynamics principle by making the electron beam emission intensity adjustable and variable during the etching process. The control unit dynamically modifies electron beam intensity based on shutter position and substrate potential conditions. This dynamic adjustment capability allows the system to optimize neutralization effectiveness while adapting to changing process conditions, preventing electrostatic damage without requiring complex manual intervention.
3Object-affected harmful factors
If the shutter closes to shield the substrate, then substrate potential stability is maintained, but etching process is interrupted
Solution Approach 1:
The system performs preliminary action by adjusting electron beam intensity before shutter closing operations. The control unit increases electron beam emission in advance to maintain substrate potential stability that will be needed when the shutter closes and ion beam is blocked. This proactive adjustment ensures continuous potential stability without requiring shutter interruptions, maintaining etching process continuity.
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 approach effectively suppresses substrate potential fluctuations, preventing ESD and stabilizing the quality of semiconductor elements, especially those vulnerable to electrostatic damage, without compromising etching precision or requiring significant adjustments to the ion beam parameters.
Implementation Method 1
an ion source which extracts positive ions from a plasma using an extraction electrode
Implementation Method 2
a substrate arranged on a substrate holder is irradiated with positive ions (ion beam) and etched
Implementation Method 3
an electron source (neutralizer) which emits electrons to neutralize the positive ions extracted from the ion source
Implementation Method 4
emitting electrons which neutralize a positive potential toward the gap between the extraction electrode and the substrate
Implementation Method 5
a shutter device which is placed between the ion source and the substrate holder, and shields the ion beam
Implementation Method 6
an exhaust device which evacuates a process chamber into a vacuum
Data Source
AI summary
A computer-readable recording medium encoded with a computer program for executing an ion etching method of etching a substrate arranged on a substrate holder using an ion beam etching apparatus. The computer program includes a decremental control program having a command according to which the first step is executed; and an incremental control program having a command according to which the second step is executed.