Cyclical Metal Oxide Etching for Nanoscale Selectivity
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Solution Overview
Problem
Existing etching processes for metal oxide layers, particularly those involving plasma-based reactive species, lack the necessary etch selectivity and precision required for nanoscale removal, and can damage unetched portions of the material, while chemical vapor etching methods lack specificity to certain materials.
Innovation Solution
A cyclical etching process using gas-phase modifier and halogen reactants, such as SiR1R2R3L and halogen gases, is employed to etch metal oxide layers, specifically hafnium zirconium oxide, with each cycle involving a gas-phase modifier reactant followed by a halogen reactant, allowing for precise control and minimal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma-based reactive ion etching is used to remove metal oxide layers, then etching speed is improved, but etch selectivity and precision deteriorate at nanometer scale
Solution Approach 1:
The etching process is divided into multiple sequential cycles, each removing a controlled amount of material. Each cycle consists of introducing a modifier reactant followed by a halogen reactant, with purge steps in between. This segmentation allows precise control over the total etch depth by accumulating controlled removal over multiple cycles, achieving nanometer-scale precision while maintaining reasonable etching speed.
Solution Approach 2:
The patent employs periodic introduction of reactants in alternating cycles. Each cycle includes a modifier reactant step followed by a halogen reactant step, repeated multiple times. This periodic action enables controlled, incremental material removal where each period contributes to the total etch depth in a manageable, precise manner, resolving the contradiction between speed and precision.
2Productivity
If plasma-based reactive ion etching is used to remove metal oxide layers, then material removal rate is improved, but damage to unetched portions increases
Solution Approach 1:
A modifier reactant is introduced as an intermediary step between the halogen reactant and the metal oxide surface. The modifier reactant modifies the surface chemistry in a controlled manner, creating a more favorable environment for the subsequent halogen etching. This intermediary step reduces the harmful effects of high-energy reactive species on unetched portions while maintaining efficient material removal.
Solution Approach 2:
The patent changes the chemical parameters of the etching environment by introducing specific modifier reactants (containing silicon, carbon, or other elements) before the halogen reactant. This parameter change modifies the surface properties and reaction chemistry, enabling controlled etching that protects unetched material from damage while maintaining high removal rates.
3Ease of manufacture
If chemical vapor etching is used to etch metal oxide layers, then process simplicity is improved, but material specificity deteriorates
Solution Approach 1:
The patent applies different reactants at different stages of the process: a modifier reactant (containing silicon, carbon, or other elements) is introduced first, followed by a halogen reactant. This local differentiation of chemical agents allows the process to be simple overall while achieving high material specificity through the coordinated action of specialized reactants tailored to the metal oxide composition.
Solution Approach 2:
The etching process uses a composite approach with multiple reactant types working together: modifier reactants (silicon-based, carbon-based, or other elements) combined with halogen reactants. This composite reaction system provides both process simplicity and high material specificity, as the combination of reactants can be optimized for different metal oxide compositions while maintaining a straightforward process flow.
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 cyclical etching process achieves precise and selective removal of metal oxide layers, particularly hafnium zirconium oxide, with high etch rates and minimal impact on the remaining material, suitable for forming high-capacitance dielectric layers in semiconductor devices.
Implementation Method 1
Vapor-phase etching methods such as chemical vapor etching (CVE) and atomic layer etching (ALEt) have received increasing attention in recent years due to a wide variety of potential applications in the semiconductor industry
Implementation Method 2
Vapor-phase reactants are commonly used that react with the surface of the material layer to produce gaseous reaction products
Data Source
AI summary
Methods for etching a metal oxide layer on a surface of a substrate in a reaction chamber by a cyclical etching process are disclosed. The cyclical etching processes include repeated etching cycles, with each etching cycle including, contacting the metal oxide layer with a gas-phase modifier reactant and contacting the metal oxide layer with a gas-phase halogen reactant. Methods for forming metal oxide layers are also disclosed, such methods include depositing a metal oxide layer on a device structure, thermally treating the deposited metal oxide, and subsequently removing a portion of the deposited metal oxide layer by cyclical etching processes.