Thermal Atomic Layer Etching with Vapor Halides for Selective Removal
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Solution Overview
Problem
Current etching processes, particularly in the field of thermal atomic layer etching, face challenges in achieving controlled and selective removal of materials without damaging the substrate, especially when dealing with complex materials like metal nitrides and oxides.
Innovation Solution
The proposed solution involves a chemical atomic layer etching process that uses sequential exposure of a substrate to a first vapor-phase halide reactant and a second vapor-phase reactant, which converts adsorbed species into volatile adducts that can be easily removed, thereby controlling the etching process without the need for plasma reactants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma reactants are used to remove adsorbed species, then etching speed is improved, but substrate damage increases
Solution Approach 1:
The invention changes the chemical parameters of the reactants from plasma-based to vapor-phase molecular species. Specifically, it uses vapor-phase halide reactants (such as NF3, CF4, SF6) instead of plasma reactants, fundamentally altering the reaction mechanism to achieve etching without plasma-induced substrate damage while maintaining controlled etching rates through thermal energy
Solution Approach 2:
The invention replaces the plasma-based physical/chemical mechanism with a purely chemical vapor-phase reaction mechanism. By substituting plasma excitation with thermal activation and molecular vapor-phase reactions, the process eliminates the harmful mechanical and electrical effects of plasma while retaining the sequential self-limiting reaction characteristics of atomic layer 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 etching process is segmented into distinct sequential pulses: first a vapor-phase halide reactant pulse to form adsorbed species, then a second vapor-phase reactant pulse to convert and remove the adsorbed species. This segmentation enables precise control over the etching reaction at each stage, maintaining atomic layer precision while using simpler molecular vapor-phase reactions compared to plasma processes
Solution Approach 2:
The invention employs periodic pulsing of different vapor-phase reactants in a cyclic manner. Each cycle consists of alternating exposure to the halide reactant and the second reactant, creating a periodic reaction pattern that enables controlled, repeatable etching with high precision while keeping the process methodology systematic and manageable
3Object-affected harmful factors
If vapor-phase halide reactants are used, then substrate damage is reduced, but etching selectivity becomes more difficult to achieve
Solution Approach 1:
The vapor-phase halide reactant acts as an intermediary that first forms adsorbed species on the substrate surface before the second reactant removes them. This two-step intermediary mechanism allows the process to be highly selective: the halide reactant selectively adsorbs onto specific materials, and the second reactant selectively reacts with the adsorbed species, achieving material-specific etching without direct plasma damage
Solution Approach 2:
The invention replaces plasma-based selective etching mechanisms with vapor-phase chemical reaction mechanisms. By using molecular vapor-phase reactants that undergo specific chemical reactions with target materials, the process achieves selectivity through chemical affinity and reaction kinetics rather than plasma physics, reducing substrate damage while maintaining or improving selectivity
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 precise control over the etching process, achieving high etch selectivity and minimizing substrate damage, as demonstrated by the effective etching of various materials such as TiN, TaN, and Al2O3 with consistent results across multiple cycles.
Implementation Method 1
exposing the substrate to a first vapor-phase halide reactant, such as a non-metal halide reactant, to form adsorbed species on the substrate
Implementation Method 2
the second vapor-phase reactant converts the adsorbed species into volatile adducts that comprise one or more atoms from the surface to be etched
Data Source
AI summary
Thermal atomic layer etching 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 halide reactant and a second vapor halide reactant. In some embodiments, the first reactant may comprise an organic halide compound. During the thermal ALE cycle, the substrate is not contacted with a plasma reactant.