Radical-Activated Metal Oxide Etching for Rate-Selectivity Balance
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in achieving high etch rates and selectivity during the removal of metal oxides while preserving adjacent materials, particularly in plasma etching where ions have higher kinetic energies but lower selectivity than radicals.
Innovation Solution
A radical-activated thermal atomic layer etching (ALE) process is employed, utilizing a grid system and neutralizer to generate radicals with increased kinetic energies, enhancing ligand exchange reactions and etch selectivity through sequential cycles of surface modification, material removal, and surface cleaning, thereby improving etch rates and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching with ions is used to increase etch rate, then etch rate is improved, but selectivity deteriorates
Solution Approach 1:
The patent changes the kinetic energy parameter of the reactive species from high (ions) to low (radicals), thereby improving selectivity while maintaining etch rate through thermal activation at elevated temperatures (200-400°C). This parameter transformation resolves the contradiction by decoupling etch rate from species kinetic energy.
Solution Approach 2:
The patent replaces the mechanical bombardment mechanism of ions with a thermal-chemical mechanism using radicals. Instead of relying on ion kinetic energy to drive the etching reaction, the process uses thermally activated radical reactions, substituting a mechanical process with a thermal-chemical one to achieve both high etch rate and high selectivity.
2Manufacturing precision
If traditional thermal ALE is used to improve selectivity, then etch selectivity is improved, but etch rate deteriorates
Solution Approach 1:
The patent introduces radical concentration as a new parameter to control the reaction kinetics. By generating high concentrations of radicals and maintaining elevated temperatures, the process accelerates the thermal ALE reaction rate, thereby improving etch rate while preserving the high selectivity inherent in thermal ALE processes.
Solution Approach 2:
The patent employs continuous radical generation through plasma or photolysis during the thermal ALE process, ensuring a sustained supply of reactive species. This continuous action maintains high reaction rates throughout the etching process, preventing the etch rate deterioration that typically occurs in traditional thermal ALE.
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 process achieves etch rates of metal oxides ranging from 1 to 5 Å per cycle with increased selectivity, minimizing damage to adjacent structures and ensuring precise material removal.
Implementation Method 1
a plasma generator configured to generate a plasma from a gas
Implementation Method 2
a grid system configured to increase a kinetic energy of ions from the plasma
Implementation Method 3
a neutralizer configured to generate electrons to neutralize the ions and generate radicals to facilitate etching of the metal oxide
Implementation Method 4
activating a ligand exchange reaction on a surface of a metal oxide with the radicals
Data Source
AI summary
The present disclosure describes methods and systems for radical-activated etching of a metal oxide. The system includes a chamber, a wafer holder configured to hold a wafer with a metal oxide disposed thereon, a first gas line fluidly connected to the chamber and configured to deliver a gas to the chamber, a plasma generator configured to generate a plasma from the gas, a grid system between the plasma generator and the wafer holder and configured to increase a kinetic energy of ions from the plasma, a neutralizer between the grid system and the wafer holder and configured to generate electrons and neutralize the ions to generate radicals, and a second gas line fluidly connected to the chamber and configured to deliver a precursor across the wafer. The radicals facilitate etching of the metal oxide by the precursor.