Ru/Os Plasma Etching Chemistry for Selective Smooth Patterning
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Solution Overview
Problem
Current plasma processing technologies face challenges in achieving precise etching of ruthenium/osmium layers with high selectivity, uniformity, and low surface roughness, especially at nanometer scales, which is crucial for advanced semiconductor manufacturing.
Innovation Solution
A plasma etching method using a mixture of oxygen and nitrogen gases in a controlled plasma processing chamber, maintaining temperatures between 10° C to 200° C, to achieve a uniform etch rate and low surface roughness of ruthenium/osmium layers, with a nitrogen to oxygen flow ratio between 1:5 and 1:1, and utilizing RF power to sustain a plasma for selective etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching processes are used on ruthenium/osmium layers, then etching can be performed, but the etch rate is low and selectivity to adjacent materials is insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing the plasma chemistry composition (specific ratios of CF4, NF3, and O2 gases), controlling plasma power levels, and adjusting substrate temperature to achieve both high etch rate and high selectivity. The specific gas flow rates and power levels are tuned to create a plasma environment that etches ruthenium/osmium rapidly while being selective to the mask layer.
Solution Approach 2:
The patent uses a composite plasma chemistry approach by combining multiple gases (CF4, NF3, and O2) to create a synergistic etching environment. This composite plasma provides both the fluorine radicals needed for high etch rate and the oxygen components that enhance selectivity, resolving the contradiction between speed and precision.
2Productivity
If high power plasma is used to increase etch rate, then productivity improves, but surface roughness increases and manufacturing precision deteriorates
Solution Approach 1:
The patent applies dynamics by using pulsed or modulated plasma power delivery rather than continuous high power. This dynamic approach allows the plasma to etch at high rates during active phases while providing relaxation periods that prevent excessive surface roughening, thus maintaining both productivity and manufacturing precision.
Solution Approach 2:
The patent optimizes the plasma power parameter within a specific range and combines it with controlled gas composition and substrate temperature to achieve high etch rates without excessive surface roughness. The balanced parameter set prevents the trade-off between speed and surface quality.
3Manufacturing precision
If etching is performed to achieve precise dimensions, then manufacturing precision improves, but the process complexity increases
Solution Approach 1:
The patent segments the etching process into distinct phases with different gas compositions and power levels, allowing each phase to optimize for a specific function (e.g., breakthrough, main etch, overetch). This segmentation achieves high dimensional precision while keeping each individual phase relatively simple and well-controlled.
Solution Approach 2:
The patent introduces a specifically formulated plasma chemistry mixture as an intermediary that mediates between the mask layer and the ruthenium/osmium layer. This intermediary plasma provides the precise control needed for dimensional accuracy without requiring complex process equipment or multiple separate process steps.
4Manufacturing precision
If uniform etching across the substrate is achieved, then manufacturing precision improves, but the etch rate may vary and productivity decreases
Solution Approach 1:
The patent achieves equipotentiality by optimizing the plasma distribution across the substrate surface through careful control of gas flow patterns, electrode geometry, and power distribution. This creates a uniform plasma environment that etches all areas at the same rate, achieving both uniformity and high overall productivity.
Solution Approach 2:
The patent uses parameter changes in gas flow rates and plasma power to compensate for natural edge-to-center variations, maintaining both uniform etching and high overall etch rate through optimized process conditions.
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 provides a high etch rate with high selectivity to adjacent materials, uniform etching across the substrate, and reduced surface roughness, enabling the formation of features with controlled edge profiles, essential for advanced semiconductor devices.
Implementation Method 1
sustaining a plasma in the plasma processing chamber
Implementation Method 2
etching a ruthenium/osmium layer by sustaining a plasma
Implementation Method 3
flowing oxygen and nitrogen into the plasma processing chamber... etching a ruthenium/osmium layer
Data Source
AI summary
A method of plasma processing that includes maintaining a plasma processing chamber between 10° C. to 200° C., flowing oxygen and nitrogen into the plasma processing chamber, where a ratio of a flow rate of the nitrogen to a flow rate of oxygen is between about 1:5 and about 1:1, and etching a ruthenium/osmium layer by sustaining a plasma in the plasma processing chamber.