Magnetic Ion Beam Steering for Atomic Layer Etch Precision
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Solution Overview
Problem
Conventional etching methods, such as reactive ion etching (RIE) and atomic layer etching (ALE), face challenges in controlling etch depth and energy distribution, leading to substrate damage and poor selectivity, especially in fine semiconductor processes.
Innovation Solution
An atomic layer etching apparatus and method that uses a magnetic field and electric field to control charged particles, adjusting their flight paths and energies to achieve precise etching of a single atomic layer without deep etching or substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reactive ion etching (RIE) is used to achieve fast anisotropic etching and high selectivity, then etching speed and selectivity are improved, but substrate damage occurs due to high-energy ion collision and lattice defects
Solution Approach 1:
The patent segments the etching process into two distinct stages: a chemical reaction stage where radicals react with the film material, and a physical removal stage where low-energy ions remove the reaction products. This segmentation allows the chemical etching to provide selectivity while the low-energy physical removal avoids substrate damage from high-energy ion collision.
Solution Approach 2:
The patent changes the energy parameter of ions from high energy (in conventional RIE) to low energy (1-10 eV) by controlling the plasma potential and ion acceleration voltage. This parameter change enables ion removal of etched material without causing substrate damage from excessive energy deposition.
2Shape
If sputter etching is used to achieve directional control by adjusting ion incident angle, then anisotropic etching is improved, but selectivity deteriorates due to direct physical collision without chemical reaction
Solution Approach 1:
The patent merges chemical etching and physical etching mechanisms into a unified process. Radicals provide chemical reaction for selective etching of specific materials, while low-energy ions provide directional removal of reaction products, combining the advantages of both chemical and physical processes.
3Productivity
If conventional ion beam extraction is used to achieve sufficient ion flux, then etching efficiency is improved, but energy distribution becomes uncontrolled leading to deep etching and poor atomic layer precision
Solution Approach 1:
The patent implements feedback control by monitoring the plasma potential and adjusting the ion acceleration voltage accordingly. This feedback mechanism maintains ions at the optimal low energy level (1-10 eV) required for atomic layer precision, preventing both insufficient etching and excessive deep etching.
Solution Approach 2:
The patent precisely controls the ion energy parameter within a narrow range of 1-10 eV, which is significantly lower than conventional RIE energies. This parameter control enables removal of only single atomic layers without penetrating deeper into the substrate, achieving atomic layer precision.
4Productivity
If high plasma density is used to increase radical concentration for faster etching, then etching rate is improved, but ion energy increases causing more substrate damage
Solution Approach 1:
The patent segments the roles of radicals and ions: radicals are responsible for chemical reaction and etching rate, while ions are responsible for directional removal at low energy. This segmentation allows high plasma density to benefit chemical reactivity without necessarily increasing ion damage, as ion energy is independently controlled.
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 apparatus efficiently etches a single atomic layer with reduced substrate damage and improved surface smoothness by filtering ion beams and applying magnetic fields to control incident angles and energies, enhancing process yield and reliability.
Implementation Method 1
a magnetic field applying module disposed in a region adjacent to a flight space of the charged particles extracted from the plasma, the magnetic field applying module being configured to apply a magnetic field to the flight space of the charged particles
Implementation Method 2
a grid assembly composed of a plurality of grids to which potentials can be applied, and configured to extract charged particles from the plasma of the plasma source by controlling potentials applied to the grids
Data Source
AI summary
Provided is an atomic layer etching apparatus comprising: a plasma source; a grid assembly composed of a plurality of grids to which potentials can be applied, disposed at the front of the plasma source, and configured to extract charged particles from the plasma; and a magnetic field applying module configured to apply a magnetic field to a flight space of the charged particles so that the charged particles are obliquely incident on a target substrate at a preset angle. The charged particles extracted from the plasma by the grid assembly fly while rotating with a preset curvature by the magnetic field and are obliquely incident on the substrate. As a result, the apparatus limits the collision energy of the charged particles when they are incident on the substrate, thereby enabling atomic layer etching of the target substrate.