Thermal Atomic Layer Etching with Sequential Halide Pulses
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Solution Overview
Problem
Current atomic layer etching processes face challenges in achieving controlled and selective removal of materials without surface contamination and damage, particularly in the absence of plasma, which limits their precision and efficiency in applications like integrated circuit fabrication.
Innovation Solution
The use of sequential pulses of vapor-phase reactants, specifically halide reactants, in a chemical atomic layer etching process where a first halide reactant forms species on the substrate surface, followed by a second halide reactant that reacts to form volatile species for removal, without plasma exposure, allowing for controlled etching cycles that can repeat until a desired level is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma is used in atomic layer etching processes, then etching efficiency is improved, but surface contamination and damage increase
Solution Approach 1:
The patent replaces the plasma-based chemical reaction mechanism with a thermal chemical reaction mechanism. Instead of using plasma to activate reactants and drive etching reactions, the invention uses thermally activated sequential reactions between vapor-phase halide reactants and substrate surface species, thereby eliminating plasma-induced surface damage and contamination while maintaining controlled etching
Solution Approach 2:
The patent changes the reaction conditions from plasma state to thermal state by controlling temperature and reactant partial pressures. The process uses elevated temperatures (typically 200-500°C) to activate the chemical reactions between halide reactants and substrate surfaces, replacing the need for plasma activation and achieving contamination-free etching
2Manufacturing precision
If sequential pulses of vapor-phase reactants are used, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The patent divides the etching process into distinct sequential steps: first exposing the substrate to a halide reactant to form surface species, then exposing to a second reactant to form volatile products. This segmentation of the chemical reaction into discrete, controllable steps enables precise etching control and selectivity while maintaining a relatively simple process architecture
Solution Approach 2:
The patent employs periodic pulsing of vapor-phase reactants, where each reactant is introduced in alternating cycles. This periodic action allows precise control over the etching rate and selectivity by adjusting pulse durations, frequencies, and reactant concentrations, achieving high manufacturing precision through time-resolved process control
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 precise and controlled etching of up to a monolayer of material per cycle, reducing surface contamination and minimizing damage to the substrate, while maintaining conformality and selectivity, suitable for complex three-dimensional structures and integrated circuits.
Implementation Method 1
The first reactant may be a halide reactant, such as a non-metal halide reactant, and comprises a first halide ligand
Implementation Method 2
The second vapor-phase reactant may react with the reactant species to form volatile species comprising one or more atoms from the substrate surface
Implementation Method 3
The volatile species may be removed from the reaction chamber, such as by purging with an inert gas
Data Source
AI summary
Atomic layer etching (ALE) processes are disclosed. In some embodiments, the methods comprise at least one etch cycle in which the substrate is alternately and sequentially exposed to a first vapor phase non-metal halide reactant and a second vapor phase halide reactant. In some embodiments both the first and second reactants are chloride reactants. In some embodiments the first reactant is fluorinating gas and the second reactant is a chlorinating gas. In some embodiments a thermal ALE cycle is used in which the substrate is not contacted with a plasma reactant.