Metal Surface Precleaning for Selective Oxide Removal Before Filling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional plasma-based cleaning techniques for removing native oxide films from metal-containing surfaces in semiconductor fabrication often cause damage to dielectric structures and low-k materials, making selective metal filling of recessed features challenging.
Innovation Solution
The use of hot vapor-phase etching in conjunction with silicon-containing gases to remove native oxide films from metal-containing surfaces, where a silicon-containing material is first deposited to protect dielectric surfaces, followed by a vapor-phase fluorine or chlorine-containing agent to remove the oxide film without damaging the dielectric material, and then residues are removed with a second silicon-containing gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma-based cleaning techniques are used to remove native oxide films from metal-containing surfaces, then the oxide film removal is effective, but damage occurs to dielectric structures and low-k materials
Solution Approach 1:
A silicon-containing material is deposited as an intermediary protective layer on dielectric surfaces before oxide removal. This intermediary layer selectively protects dielectric structures during the oxide removal process, allowing effective oxide film removal from metal surfaces without damaging the dielectric materials.
Solution Approach 2:
The cleaning process is made selective through local quality differentiation. The silicon-containing material provides localized protection to dielectric surfaces, while the vapor-phase fluorine or chlorine-containing agent selectively removes oxide films from metal-containing surfaces. This creates different functional zones: protected dielectric areas and actively cleaned metal areas, resolving the contradiction between effective cleaning and dielectric protection.
2Manufacturing precision
If plasma cleaning is used to pre-clean metal surfaces before metal deposition, then the metal deposition quality is improved, but the dielectric material structure is damaged
Solution Approach 1:
The silicon-containing material serves as a protective intermediary that preserves dielectric structure profiles during the cleaning process. By depositing this protective layer before oxide removal, the dielectric structures maintain their original shapes and profiles, while still achieving the necessary oxide film removal for high-quality metal deposition.
Solution Approach 2:
The process transitions from plasma-based cleaning to vapor-phase chemical cleaning, changing the physical and chemical parameters of the cleaning mechanism. This parameter change allows selective oxide removal without the broad-spectrum damage caused by plasma, thereby preserving dielectric structure integrity while maintaining metal deposition quality.
3Object-affected harmful factors
If hot vapor-phase etching is used to remove native oxide films, then dielectric material is protected, but residues remain on the metal-containing surface
Solution Approach 1:
The process employs a two-step approach where residues from the hot vapor-phase etching are subsequently removed by exposure to a second silicon-containing gas. This allows the beneficial dielectric protection during oxide removal, followed by residue elimination to prepare the surface for optimal metal deposition.
Solution Approach 2:
The cleaning process is extended into a continuous sequence: first hot vapor-phase etching removes oxide films while protecting dielectrics, then a second silicon-containing gas treatment removes residues. This continuous action ensures both dielectric protection and surface cleanliness, with each step building on the previous step's results.
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 removes native oxide films without plasma-based damage, enabling improved metal filling performance by protecting dielectric materials and minimizing residue impact, thus facilitating successful metal deposition on surfaces like titanium nitride prior to ruthenium or other low-resistivity metals.
Implementation Method 1
exposing the substrate to a first silicon-containing gas to deposit a silicon-containing material onto the exposed surfaces of the substrate by vapor-phase deposition
Implementation Method 2
exposing the substrate to a vapor-phase fluorine-containing agent to remove the oxide film from the metal-containing surface
Implementation Method 3
exposing the substrate to a second silicon-containing gas to remove residues from the pre-cleaned metal-containing surface
Data Source
AI summary
Improved process flows and methods are provided for processing a semiconductor substrate have exposed dielectric and metal-containing surfaces. More specifically, improved process flows and methods are provided for pre-cleaning the metal-containing surfaces prior to depositing a metal material onto the metal-containing surfaces. Hot vapor-phase etching is used to remove a native oxide film from the metal-containing surfaces. Prior to hot vapor-phase etching, the semiconductor substrate is exposed to a first silicon-containing gas to deposit an inhibitor film onto the exposed dielectric and metal-containing surfaces. The inhibitor film protects the dielectric surfaces while the native oxide film is being removed via the hot vapor-phase etching. In some embodiments, the semiconductor substrate is exposed to a second silicon-containing gas, after hot vapor-phase etching, to remove residues of the hot vapor-phase etching process from the pre-cleaned metal-containing surfaces.