Electrically Neutral Cluster Jet for High-Precision Semiconductor Etching
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Solution Overview
Problem
Existing methods using gas cluster ion beams for surface processing, such as semiconductor and MEMS element fabrication, face challenges like electrical damage and poor precision due to ionization and plasma etching, which affect the integrity and characteristics of the materials.
Innovation Solution
A cluster jet processing method using an adiabatically expanded reactive cluster formed from a mixed gas of a reactive gas and a gas with a lower boiling point, which is electrically neutral, is employed to process samples, eliminating the need for electrical neutralization and reducing side etching and undercutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas cluster ion beam is used for surface processing, then material removal and surface cleaning are enabled, but electrical damage to the sample occurs due to ionization
Solution Approach 1:
The invention changes the electrical state parameter of the gas cluster from ionized to electrically neutral by omitting the ionization step. The gas cluster is directly jetted onto the sample surface without electron beam irradiation, transforming the processing mode from ion beam to neutral cluster beam, thereby eliminating electrical damage while maintaining material removal capability
Solution Approach 2:
The invention extracts and removes the ionization step from the gas cluster processing sequence. By taking out the electron beam irradiation and ion acceleration stages, the process uses only the physical jetting of electrically neutral gas clusters, eliminating the harmful electrical effects while preserving the beneficial material removal and surface cleaning functions
2Manufacturing precision
If plasma anisotropic etching is used for deep boring and penetration hole formation, then high aspect ratio structures can be formed, but material characteristics such as threshold voltages and permittivity are altered
Solution Approach 1:
The invention changes the thermal and chemical environment parameters by replacing plasma with electrically neutral gas clusters. This parameter change prevents plasma-induced modifications to material characteristics such as threshold voltages and permittivity, while maintaining the ability to form high aspect ratio structures through controlled cluster jetting
Solution Approach 2:
The invention substitutes the plasma-based chemical etching mechanism with a physical cluster jetting mechanism. By replacing the plasma field with direct mechanical jetting of neutral gas clusters, the process achieves anisotropic etching through physical momentum transfer rather than chemical reactions, preserving material composition stability
3Productivity
If plasma processing or dipping etching is used for pattern formation, then material removal is achieved, but side etching and undercutting increase
Solution Approach 1:
The invention applies local quality control by directing gas clusters precisely at the intended etching locations through controlled jetting. The localized impact of neutral clusters provides highly directional material removal with minimal lateral spread, reducing side etching and undercutting while maintaining efficient pattern formation
Solution Approach 2:
The invention uses pneumatic jetting of gas clusters to achieve precise, directional material removal. The controlled gas flow provides focused impact with minimal dispersion, enabling high precision patterning without the lateral etching problems associated with plasma or liquid etching methods
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 method enables high-precision anisotropic etching with reduced electrical damage, allowing for deep boring and miniaturized patterns without altering material characteristics, improving the straightness and accuracy of processing.
Implementation Method 1
a mixed gas composed of a reactive gas and a gas having a boiling point lower than that of the reactive gas is jetted out from a gas jetting part of a vacuum process room by a pressure in a range in which the mixed gas is not liquefied, in a predetermined direction, while being adiabatically-expanded, thereby generating a reactive cluster
Data Source
AI summary
A method for processing a sample using an electrically neutral reactive cluster is provided. The surface of a sample is processed by jetting out a mixed gas that is composed of a reactive gas and a gas with a boiling point lower than that of the reactive gas from a gas jetting part of a vacuum process room in which the sample is placed by a pressure in a range in which the mixed gas is not liquefied, in a predetermined direction, while adiabatically-expanding the mixed gas, thereby generating a reactive cluster and jetting the reactive cluster against the sample in the vacuum process room.