Barrier-Less Low-Resistivity Contacts via Selective Oxide Cleaning
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Solution Overview
Problem
The deposition of low resistivity metal films becomes challenging as devices shrink and more complex patterning schemes are used in semiconductor fabrication, requiring effective methods to clean metal surfaces while minimizing damage to dielectric surfaces.
Innovation Solution
A method involving exposure of a metal surface with a metal oxide layer to a metal halide to remove the oxide, followed by filling the feature with a conductive material without an interposed layer, using processes like atomic layer deposition or chemical vapor deposition, which can be selective or non-selective to the metal surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods are used to remove metal oxide from metal surfaces, then the metal surface is effectively cleaned, but the dielectric surface suffers significant damage
Solution Approach 1:
The patent introduces metal halide as an intermediary chemical agent that selectively reacts with metal oxide to form volatile metal halides, enabling oxide removal without direct contact between the cleaning process and dielectric surfaces. The metal halide acts as a mediator that targets only the metal oxide component while leaving the dielectric material unaffected.
Solution Approach 2:
The patent utilizes changes in chemical reactivity parameters by selecting metal halides with specific affinities for metal oxides. By controlling the chemical parameters of the cleaning agent (metal halide selection, concentration, exposure time), the process achieves selective oxide removal while preserving the dielectric surface integrity.
2Reliability
If a barrier layer is inserted between conductive material and metal surface to prevent oxidation, then oxidation is prevented, but the contact resistance increases
Solution Approach 1:
The patent performs preliminary cleaning of the metal surface by removing oxide layers before depositing the conductive material. This preliminary action ensures that the metal surface is in a clean, oxide-free state prior to conductive material deposition, eliminating the need for subsequent barrier layers that would increase contact resistance.
Solution Approach 2:
The patent converts the potentially harmful effect of metal oxidation into a beneficial process step. By intentionally exposing the metal surface to metal halide vapor, the process transforms existing oxide layers or prevents oxide formation, turning a problematic oxidation issue into a controlled cleaning mechanism that improves electrical contact.
3Manufacturing precision
If multiple processing steps are used to clean metal surfaces and deposit conductive material, then the quality is improved, but the process complexity increases
Solution Approach 1:
The patent combines the metal oxide removal step and the conductive material deposition step into a single integrated process sequence within the same chamber. The metal halide cleaning and subsequent atomic layer deposition are merged into one continuous operation, eliminating the need for separate cleaning chambers and reducing overall process complexity.
Solution Approach 2:
The patent makes the processing chamber multi-functional by enabling it to perform both cleaning (via metal halide exposure) and deposition (via atomic layer deposition) functions. This universal chamber design replaces the need for dedicated separate chambers for each function, simplifying the overall device architecture.
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 cleans metal surfaces with minimal damage to dielectric surfaces, allowing for direct contact between the conductive material and both metal and dielectric surfaces, enhancing the deposition of low resistivity metal films in semiconductor fabrication.
Implementation Method 1
exposing the feature to a metal halide to remove the layer of metal oxide from the metal surface
Implementation Method 2
filling the feature with a conductive material... using processes like atomic layer deposition or chemical vapor deposition
Implementation Method 3
filling the feature with a conductive material... using processes like atomic layer deposition or chemical vapor deposition
Data Source
AI summary
Methods of filling features including metal and dielectric surfaces with conductive materials involve cleaning the metal surfaces with little or no damage to the dielectric surfaces. After cleaning, the feature may be exposed to one or more reactants to fill the feature with the conductive material in an atomic layer deposition (ALD) or chemical vapor deposition (CVD) process. Deposition may be selective or non-selective to the metal surface. In some embodiments, the filled feature is barrier-less, such that the conductive material directly contacts the metal and dielectric surfaces with no interposing barrier or adhesion layer.