Microwave Reduction of Molybdenum Oxide on Semiconductor Metal Surfaces
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Solution Overview
Problem
Current methods for removing surface metal oxides from metal materials often require high temperatures and plasma processes that can damage adjacent dielectric materials and affect the selectivity of metal deposition processes, and are not universally applicable to different metal oxide materials.
Innovation Solution
A microwave process is used to reduce metal oxides at relatively low temperatures without exposing them to plasma, utilizing carbon monoxide gas and microwave energy to convert molybdenum oxide to pure molybdenum, maintaining the integrity of surrounding materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen plasma or high energy argon sputtering is used to remove metal oxides, then metal oxide removal is effective, but adjacent dielectric materials are damaged and selectivity of metal deposition processes is adversely affected
Solution Approach 1:
The patent changes the processing parameters by using a combination of hydrogen gas and microwave energy at controlled power levels (50-300 watts) to reduce metal oxides at lower temperatures, avoiding the high temperature plasma conditions that damage dielectric materials while maintaining effective oxide removal
Solution Approach 2:
The patent substitutes the mechanical/physical sputtering process with a chemical reduction process using hydrogen gas activated by microwave energy, replacing the high-energy physical bombardment with a controlled chemical reaction that selectively reduces metal oxides without damaging surrounding dielectric materials
2Reliability
If high processing temperatures greater than 300°C are used to remove metal oxides, then oxide removal is achieved, but surrounding materials are damaged
Solution Approach 1:
The patent replaces thermal processing with microwave-assisted chemical reduction, using hydrogen gas and microwave energy to achieve oxide removal at lower temperatures through chemical reaction rather than thermal energy, thereby avoiding damage to temperature-sensitive dielectric materials
3Adaptability or versatility
If different plasma sources and reactant gas mixtures are used for different metal oxide materials, then specific oxide removal is optimized, but process complexity increases
Solution Approach 1:
The patent establishes a universal processing method using hydrogen gas and microwave energy that can effectively remove multiple types of metal oxides (tungsten oxide, molybdenum oxide, cobalt oxide, ruthenium oxide, copper oxide) with a single standardized process configuration, eliminating the need for different plasma sources and gas mixtures for each material type
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 method effectively converts over 95% of molybdenum oxide to pure molybdenum at low temperatures, minimizing damage to dielectric materials and improving the selectivity of subsequent processing steps.
Implementation Method 1
applying a microwave energy to the process gas to perform a redox operation on a portion of the semiconductor structure
Implementation Method 2
The method further includes applying a microwave energy to the process gas to perform a redox operation on a portion of the semiconductor structure
Data Source
AI summary
Embodiments of the disclosure generally relate to methods for converting surface metal oxides to pure metal. In particular, embodiments of the disclosure pertain to methods for reducing metal oxides by microwave process. In some embodiments, a method includes positioning a semiconductor structure within a processing chamber. The semiconductor structure includes an SiO2 layer deposited on a substrate surface, a hardmask layer deposited over the SiO2 layer, a feature formed from a low-k dielectric material deposited over a portion of the hardmask layer, and a metal layer deposited in the feature. The metal layer includes a molybdenum (Mo) layer and a molybdenum oxide layer (MoOx). The method further includes flowing a process gas into the processing chamber. The process gas includes carbon monoxide. The method further includes applying a microwave energy to the process gas to perform a redox operation on a portion of the semiconductor structure.