Substrate Processing for Tungsten Oxide Reduction and Residue Removal
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Solution Overview
Problem
In semiconductor device manufacturing, the formation of tungsten oxide films on metal layers leads to increased resistance and embedding failures due to residual titanium and chlorine from halogen-containing gases used for reduction, which also inhibit the formation of subsequent metal layers like ruthenium.
Innovation Solution
A substrate processing method involving the supply of a halogen-containing gas, such as titanium tetrachloride, to reduce tungsten oxide films, followed by a reducing gas, like hydrogen plasma, to remove residues and decrease oxygen content, thereby reducing wiring resistance and preventing embedding failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a halogen-containing gas is supplied to reduce a metal oxide film, then the metal oxide film is reduced, but residue remains on the metal layer
Solution Approach 1:
The patent divides the reduction process into two distinct stages: first supplying a halogen-containing gas to reduce the metal oxide film, then supplying a reducing gas to remove the residue. This segmentation allows each gas to perform its specific function optimally without interference.
Solution Approach 2:
The patent maintains continuous processing by sequentially supplying different gases without interrupting the substrate processing. The halogen-containing gas treatment is immediately followed by reducing gas treatment, ensuring continuous removal of both oxide film and residue.
2Manufacturing precision
If halogen-containing gas is used for reduction, then metal oxide film is removed, but wiring resistance increases due to residue
Solution Approach 1:
The patent extracts the harmful residue from the metal layer by introducing a reducing gas that specifically reacts with and removes the residue while preserving the reduced metal oxide film. This extraction process eliminates the cause of increased wiring resistance.
Solution Approach 2:
The patent changes the chemical environment by switching from a halogen-containing atmosphere to a reducing gas atmosphere. This parameter change in gas composition enables the removal of residue that cannot be removed by the halogen-containing gas alone.
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 effectively reduces tungsten oxide films, decreases residue content, and suppresses the occurrence of embedding failures, resulting in lower resistance and improved formation accuracy of metal wiring layers.
Implementation Method 1
supplying a halogen-containing gas to the substrate and reducing a metal oxide film formed on a surface of the metal layer
Implementation Method 2
supplying a reducing gas to the substrate and decreasing a residue remaining on the metal layer by supplying the halogen-containing gas
Data Source
AI summary
Provided is a substrate processing method for processing a substrate including a metal layer, the method comprising: supplying a halogen-containing gas to the substrate and reducing a metal oxide film formed on a surface of the metal layer; and supplying a reducing gas to the substrate and decreasing a residue remaining on the metal layer by supplying the halogen-containing gas.