SnO2 Chamber Cleaning Using Hydrocarbon-Assisted H2 Plasma
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Solution Overview
Problem
During plasma etching processes, tin oxide (SnO2) residue in semiconductor processing chambers often forms tin powder upon decomposition, leading to contamination and defects in subsequent processing steps, as existing H2 plasma chemistry is inefficient in preventing this decomposition.
Innovation Solution
Introducing a mixture of hydrogen and hydrocarbon gases into the plasma processing system, with a ratio of hydrocarbon to hydrogen flow between 1% and 60%, which reacts with SnH4 to form a volatile organotin compound, reducing the decomposition of SnH4 into Sn powder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If H2 plasma chemistry is used to etch SnO2 residue, then etching efficiency is improved, but SnH4 decomposes into Sn powder causing contamination
Solution Approach 1:
The patent introduces hydrocarbon gas as an intermediary substance that reacts with SnH4 to form volatile organotin compounds. This intermediary reaction prevents SnH4 from decomposing into Sn powder while maintaining the etching process effectiveness. The hydrocarbon gas acts as a mediator between SnH4 and the final volatile product.
Solution Approach 2:
The patent changes the chemical composition parameters of the plasma environment by introducing hydrocarbon gas mixed with hydrogen gas at specific ratios (1% to 60%). This parameter change transforms the reaction pathway from SnH4 decomposition to organotin compound formation, eliminating Sn powder contamination while preserving etching capability.
2Manufacturing precision
If SnO2 film is cleaned from chamber walls, then processing quality is improved, but Sn powder deposits on chamber surfaces
Solution Approach 1:
The patent converts the harmful decomposition reaction of SnH4 into Sn powder by introducing hydrocarbon gas that reacts with SnH4 to form volatile organotin compounds. This transforms a harmful process (powder formation) into a beneficial one (volatile compound evacuation), effectively cleaning the chamber without leaving powder deposits.
Solution Approach 2:
Hydrocarbon gas serves as an intermediary that captures SnH4 before it can decompose into harmful Sn powder. The intermediary reaction produces volatile organotin compounds that can be easily evacuated, preventing chamber contamination while achieving thorough cleaning.
3Object-generated harmful factors
If hydrocarbon gas is introduced to prevent Sn powder formation, then contamination is reduced, but process complexity increases
Solution Approach 1:
The patent manages the increased complexity by systematically controlling gas flow parameters within defined ranges (hydrocarbon to hydrogen ratio of 1% to 60%). This parameter control approach provides a structured method to manage the dual-gas system while achieving the desired reduction in Sn powder formation.
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 approach effectively reduces the formation of tin powder during etching and cleaning processes, allowing for efficient evacuation of SnO2 residue without contaminating the processing chamber, thereby preventing defects and ensuring cleaner processing environments.
Implementation Method 1
etching the SnO2 residue with the hydrogen gas produces stannane (SnH4)
Implementation Method 2
the SnH4 gas reacts with the hydrocarbon gas to produce an organotin compound that is volatilizable
Implementation Method 3
etching the SnO2 residue from surfaces of the processing chamber using plasma generated by a plasma source
Implementation Method 4
evacuating the processing chamber of the organotin compound
Data Source
AI summary
A plasma processing system is provided. The system includes a hydrogen gas supply and a hydrocarbon gas supply and a processing chamber. The system includes a first mass flow controller (MFC) for controlling hydrogen gas flow into the processing chamber and a second MFC for controlling hydrocarbon gas flow into the processing chamber. The system includes a plasma source for generating plasma at the processing chamber. The plasma is for etching SnO2. The system includes a controller for regulating the first MFC and the second MFC such that a ratio of hydrocarbon gas flow to the hydrogen gas flow into the processing chamber is between 1% and 60% so that when SnH4 is produced during said etching SnO2. The SnH4 is configured to react with hydrocarbon gas to produce an organotin compound that is volatilizable in a reaction that is more kinetically favorable than SnH4 decomposition into Sn powder. Producing the organotin compound enables suction of Sn out of the processing chamber to prevent Sn powder from being deposited on the surfaces of the processing chamber during said etching SnO2.