Thermal Atomic Layer Etching Using Sequential Halide Pulses
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Solution Overview
Problem
Current atomic layer etching (ALE) processes face challenges in achieving precise and controlled removal of materials without surface contamination, particularly with existing methods that rely on plasma excitation.
Innovation Solution
The proposed solution involves a thermal ALE process using sequential pulses of vapor-phase reactants, specifically non-metal halide reactants, to remove up to a monolayer of material from a substrate in each cycle, without the use of plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma excitation is used in atomic layer etching, then etching efficiency is improved, but surface contamination and damage occur
Solution Approach 1:
The patent replaces plasma-based etching (which uses excited species and ion bombardment) with a purely chemical vapor-phase process. The etching is achieved through sequential exposure to organometallic precursors that chemically react with the film material to form volatile products, eliminating the need for plasma and its associated surface damage while maintaining controlled etching rates
Solution Approach 2:
The patent changes the fundamental parameters of the etching process by using thermal energy and chemical reactivity instead of plasma excitation. By carefully controlling temperature, pressure, and precursor delivery timing, the process achieves controlled material removal without the harmful effects of plasma, demonstrating parameter optimization to resolve the contradiction between efficiency and surface quality
2Manufacturing precision
If sequential pulses of vapor-phase reactants are used, then precise material removal is achieved, but process complexity increases
Solution Approach 1:
The etching process is segmented into distinct sequential steps: first exposure to an organometallic precursor that reacts with the film, then purge to remove excess precursor, followed by exposure to a second precursor that forms volatile etch products. This segmentation allows precise control over material removal while making each individual step simple and well-understood
Solution Approach 2:
The patent uses organometallic precursor compounds as intermediaries to transfer the etching function. These precursors serve as mediators that chemically interact with the film material, enabling controlled material removal through well-defined chemical reactions rather than direct physical or plasma-based processes
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 allows for controlled and selective etching, effectively removing surface contamination and achieving precise material removal, while avoiding the damage associated with plasma etching.
Implementation Method 1
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 2
The first vapor-phase reactant may form reactant species on the substrate surface
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.