Electron Wavefront Atomic Layer Etching With Bias-Tuned ESD
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Solution Overview
Problem
In DC plasma material processing, precise control of the kinetic energy of free electrons is challenging due to uncertainties in the surface floating potential of substrates, leading to potential damage and lack of selectivity in atomic layer etching.
Innovation Solution
The method involves generating a volume of gaseous plasma with uniform steady-state composition in a DC plasma chamber, adjusting the floating potential to a reference level, and applying a sequence of biasing signals to create wafer-scale waves of electrons that target specific energy levels of atoms on the substrate, allowing precise control and selective etching of atomic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If externally applied bias signal is used to accelerate electrons towards substrate, then material processing can be performed, but the energy of electrons may not correlate to the electron energy thresholds of materials due to unknown surface floating potential
Solution Approach 1:
The system measures the surface floating potential of the substrate in real-time and uses this measurement to dynamically adjust the externally applied bias signal. This feedback loop ensures that the electron energy at the substrate surface precisely matches the desired energy threshold for selective material processing, eliminating the uncertainty caused by unknown floating potential.
Solution Approach 2:
The system changes the bias signal parameters (voltage, frequency) based on the measured surface floating potential to maintain precise electron energy control. By adjusting these parameters dynamically, the system ensures electrons arrive at the substrate with the exact energy needed for selective etching or modification of specific materials.
2Productivity
If high energy electrons are used for etching, then material removal efficiency increases, but surface damage beyond targeted physical alterations occurs
Solution Approach 1:
The system precisely controls electron energy parameters to match the specific energy thresholds required for breaking bonds of the target material. By tuning the electron energy to the minimum required value, the system achieves efficient etching while avoiding excessive energy that would cause subsurface damage or collateral harm to the substrate surface.
Solution Approach 2:
The system applies electron energy locally and selectively to specific material regions based on their unique energy thresholds. Different areas of the substrate receive electrons with energies tailored to their specific material composition, enabling precise etching of target materials while preserving surrounding areas that should not be affected.
3Quantity of substance
If DC plasma is used for material processing, then bulk material transformation can be achieved, but precise control of electron kinetic energy is challenging
Solution Approach 1:
The system incorporates real-time measurement of surface floating potential and uses this feedback to adjust the bias signal applied to the DC plasma. This closed-loop control enables precise electron energy management within the bulk plasma environment, ensuring that electrons maintain the correct kinetic energy throughout the plasma volume and at the substrate surface.
Solution Approach 2:
The system dynamically adjusts plasma parameters and bias signals in response to measured conditions, transforming the static DC plasma into a dynamically controllable environment. This allows the plasma to adapt its electron energy distribution in real-time, maintaining manufacturing precision while processing bulk materials.
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 enables precise and selective etching of atomic layers with minimal surface damage, achieving high specificity and selectivity by controlling the kinetic energy of electrons to match the energy levels of substrate atoms, thereby improving the accuracy and efficiency of material processing.
Implementation Method 1
applying a positive biasing potential to the substrate that is positive with respect to the floating potential; based on the applying, drawing electrons from the volume of gaseous plasma to the surface of the substrate and imparting an energy level to drawn electrons
Implementation Method 2
forming a corrosion layer on the substrate, the corrosion layer comprising corrosion layer species formed by adsorption of the reactive species to atoms of an atomic layer at the surface of the substrate
Implementation Method 3
based on the stimulating, desorbing the corrosion layer species, thereby etching away the atomic layer
Data Source
AI summary
Atomic layer etching of a substrate using a wafer scale wave of precisely controlled electrons is presented. A volume of gaseous plasma including diluent and reactive species and electrons of a uniform steady state composition is generated in a positive column of a DC plasma proximate the substrate. A corrosion layer is formed on the substrate by adsorption of the reactive species to atoms at the surface of the substrate. The substrate is positively biased to draw electrons from the volume to the surface of the substrate and impart an energy to the electrons so to stimulate electron transitions in the corrosion layer species, resulting in ejection of the corrosion layer species via electron stimulation desorption (ESD). The substrate is negatively biased to repel the electrons from the surface of the substrate back to the volume, followed by a zero bias to restore the steady state composition of the volume.