Thermal Atomic Layer Etching with Halide Pulses for Conformal Removal
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Solution Overview
Problem
Current atomic layer etching processes are limited in their ability to achieve controlled and selective removal of materials without damaging the substrate, particularly for complex features and non-line of sight areas, as they often rely on plasma reactants that can be damaging and lack precise control over etching cycles.
Innovation Solution
A chemical atomic layer etching process using sequential pulses of vapor-phase halide reactants, where a first halide reactant forms adsorbed species on the substrate surface, and a second reactant converts these species into volatile products, allowing for controlled etching without plasma exposure, enabling isotropic etching of non-line of sight features and reducing substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma reactants are used in atomic layer etching processes, then material removal capability is improved, but substrate damage increases
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using vapor-phase halide reactants instead of plasma reactants. This parameter change allows material removal through chemical reactions that form volatile products, achieving etching capability while avoiding the damaging effects of plasma on the substrate.
Solution Approach 2:
The patent substitutes the plasma-based physical/chemical process with a purely chemical vapor-phase process. By replacing plasma reactants with vapor-phase halide reactants, the process achieves material removal through chemical reactions rather than plasma-induced processes, thereby reducing substrate damage while maintaining etching effectiveness.
2Productivity
If conventional etching processes are used, then etching speed is improved, but control precision over etching cycles deteriorates
Solution Approach 1:
The patent segments 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 allows precise control over each step while maintaining overall etching speed, as each pulse can be independently optimized for duration and concentration.
Solution Approach 2:
The patent employs periodic pulsing of vapor-phase reactants through the reaction chamber, alternating between halide reactant pulses and second reactant pulses. This periodic action provides precise temporal control over the etching cycles, allowing accurate control of material removal while maintaining efficient etching rates through optimized pulse frequencies and durations.
3Manufacturing precision
If anisotropic etching is used for line of sight features, then etching precision is improved, but ability to etch non-line of sight features deteriorates
Solution Approach 1:
The patent creates a universal vapor-phase etching process that can handle both line-of-sight and non-line-of-sight features through the same mechanism. The vapor-phase halide reactants can diffuse and react uniformly across all substrate surfaces regardless of geometry, providing consistent etching precision for planar features while also achieving conformal coverage on three-dimensional and non-line-of-sight structures.
Solution Approach 2:
The patent utilizes vapor-phase chemistry where gaseous reactants flow through the reaction chamber and deposit/react on substrate surfaces. This pneumatic approach allows the vapor-phase halide reactants to access and etch non-line-of-sight features through diffusion and convection, while maintaining precise control over the etching process through gas flow management and pulse timing.
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 allows for precise and controlled etching of materials like TiN, TaN, SiN, and Al2O3, with high conformality and selectivity, achieving efficient removal of thin films while minimizing damage to the substrate, and can be repeated multiple times to achieve desired thickness or material removal.
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 surface
Implementation Method 2
exposing the substrate to a second vapor-phase reactant, wherein the second vapor-phase reactant converts the adsorbed species into volatile species
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.