Microwave Preclean for Low-Temperature Oxide and Halogen Removal
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Solution Overview
Problem
Conventional high-temperature etch processes for removing molybdenum oxide and tungsten oxide in semiconductor fabrication recess underlying metal layers and fail to completely eliminate chlorine or fluorine residues, degrading dielectric layers and causing voids in the BEOL process.
Innovation Solution
A low-temperature non-plasma microwave preclean process using a microwave source to deliver hydrogen gas and microwave energy within a processing chamber, maintaining substrate temperatures below 300°C to selectively remove halogen-containing and metal oxide contaminants without generating plasma, thereby avoiding damage to underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high-temperature etch process is used to remove metal oxides, then the metal oxides (molybdenum oxide and tungsten oxide) are effectively removed, but the underlying metal layer is recessed and bottom voids are formed
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperature (450°C) to low temperature (below 300°C) and changes the plasma state parameter from plasma-generating to non-plasma microwave heating, thereby removing metal oxides without damaging the underlying metal layer
Solution Approach 2:
The patent replaces the conventional plasma-based etching mechanism with a microwave-heating-based chemical reaction mechanism, where microwave energy heats the process gas to enable selective removal of metal oxides without the harmful effects of plasma on the underlying layer
2Manufacturing precision
If a high-temperature etch process is used to remove metal oxides, then the metal oxides are removed, but chlorine or fluorine residues remain and degrade dielectric layers
Solution Approach 1:
The patent changes the temperature parameter to low temperature (below 300°C) and uses non-plasma microwave heating with specific process gases to achieve complete removal of both metal oxides and halogen residues, preventing dielectric layer degradation
Solution Approach 2:
The patent introduces a process gas as an intermediary that, when heated by microwave energy, enables the chemical removal of halogen residues without leaving degradation-causing contaminants on the dielectric layer
3Manufacturing precision
If a conventional etch process is used, then metal oxides can be removed, but the process requires high temperature which causes process complexity and underlying layer damage
Solution Approach 1:
The patent replaces the complex high-temperature plasma etching system with a simpler low-temperature microwave heating system, eliminating the need for high temperature control while achieving effective surface cleaning
Solution Approach 2:
The microwave energy directly heats the process gas to the required temperature for the chemical reaction, eliminating the need for external heating systems and complex temperature control mechanisms
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
Effectively removes metal oxides and halogen residues at low temperatures, preventing damage to underlying layers and ensuring the integrity of dielectric layers, thus addressing the void and degradation issues in the BEOL process.
Implementation Method 1
delivering microwave energy, from the microwave source, to the processing gas
Implementation Method 2
the flowing process gas and the delivering microwave energy is configured to remove a halogen containing material from a surface of the substrate and/or a metal oxide from the surface of the substrate
Data Source
AI summary
Embodiments of the present disclosure generally relate to a low temperature non-plasma containing preclean process to selectively remove contaminants from the surface of a substrate, such as halogen containing and/or metal oxide containing contaminants. The non-plasma containing precleaning process is performed at a low temperature by use of a microwave source that is configured to provide microwave energy to the processing gases disposed within a processing chamber. The non-plasma low temperature preclean process is effective in reducing halogen containing residues, such as fluorine and chlorine containing residues formed on a surface of a substrate.