SiO2 Passivation for Selective ALD Without Unwanted Nucleation
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Solution Overview
Problem
Current atomic layer deposition (ALD) methods face challenges in scaling high conductivity TaN and metallic Ta diffusion barriers for Cu deposition in vias and interconnects, as existing self-assembled monolayers (SAMs) require elevated temperatures and long reaction times to effectively passivate surfaces and inhibit metal, metal oxide, and metal silicide deposition.
Innovation Solution
A method involving pre-treating an oxide layer surface to render it hydrophilic, followed by exposure to a passivant that binds below 200°C to SiOx, CuOx, or CoOx, and subsequent annealing to selectively grow metal, metal oxide, or metal silicide layers by ALD, using compounds like DPPETS and TMDS to achieve hydrophobicity and prevent unwanted nucleation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SAMs such as HMDS or ODTS are used to passivate SiO2 surfaces, then deposition inhibition is achieved, but elevated temperatures (100+°C) and long reaction times (24-48 hours) are required
Solution Approach 1:
The patent changes the chemical parameters of the passivant molecule by introducing a phosphino group in DPPETS, which fundamentally alters the reaction mechanism. This enables passivation at lower temperatures (below 200°C) and shorter times compared to conventional SAMs like HMDS or ODTS that require 100+°C and 24-48 hours
Solution Approach 2:
The phosphino group in DPPETS acts as a chemical intermediary that facilitates rapid binding to SiOx surfaces at lower temperatures. This intermediary functional group enables the passivation reaction to proceed efficiently without requiring the high thermal energy needed for conventional silane-based SAMs
2Reliability
If conventional SAMs are used for passivation, then surface coverage is achieved, but the process requires elevated temperatures and long reaction times
Solution Approach 1:
The patent changes the thermal reaction parameters by using DPPETS with a phosphino group that enables passivation below 200°C, whereas conventional SAMs require 100+°C. This parameter change in the chemical structure leads to lower processing temperatures while maintaining effective surface coverage
3Reliability
If PVD Ta/TaN diffusion barrier is used for Cu deposition, then diffusion protection is provided, but scaling is challenging and high conductivity TaN and metallic Ta cannot be deposited via ALD
Solution Approach 1:
The patent uses a self-assembled monolayer (DPPETS) as a chemical intermediary that provides diffusion barrier functionality without requiring PVD processes. This SAM-based approach enables subsequent ALD deposition of high conductivity materials, bridging the gap between diffusion protection and ALD compatibility
Solution Approach 2:
The patent replaces the mechanical/PVD-based Ta/TaN diffusion barrier with a chemically-based SAM system. This substitution enables the use of ALD processes for depositing diffusion barriers, improving scalability and allowing deposition of materials like high conductivity TaN and metallic Ta that are not accessible via conventional PVD methods
4Reliability
If non-metallic films are used to enable bottom-up fill, then resistivity is decreased, but effective suppression of metal, metal oxide, and metal silicide ALD requires specific SAM properties that are difficult to achieve
Solution Approach 1:
The patent changes the chemical parameters of the passivant by using DPPETS with a phosphino group, which provides effective suppression of metal, metal oxide, and metal silicide ALD. This chemical modification simplifies the SAM selection process by providing a universal passivant that works across multiple material systems without requiring complex optimization
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 enables selective and efficient deposition of metals and metal oxides with reduced resistivity, maintaining hydrophobicity and preventing unwanted nucleation, thereby overcoming the limitations of existing SAMs in ALD processes.
Implementation Method 1
exposing the oxide layer to a passivant, wherein the passivant binds to —OH or O on silicon oxide (SiOx), copper oxide (CuOx), and/or cobalt oxide (CoOx) below about 200° C.
Implementation Method 2
Self-assembled organic monolayers fulfill this requirement, but the SAM must be chosen which can rapidly form a particle free conformal coating at low temperature
Implementation Method 3
pre-treating a surface of the oxide layer, the surface of the oxide layer comprising hydroxyl groups, wherein the pre-treating cleans and renders the surface of the oxide layer hydrophilic
Implementation Method 4
the surface of the oxide layer is rendered hydrophobic after exposure to the passivant
Data Source
AI summary
The present inventive concept is related to methods for passivating an oxide layer and methods of selectively depositing a metal, metal nitride, metal oxide, or metal silicide layer on a metal, metal oxide, or silicide layer over an oxide layer including exposing the oxide layer to a passivant that selectively binds to the oxide layer over the metal, metal oxide, or silicide layer, and selectively growing the metal, metal nitride, metal oxide or metal silicide layer on the metal, metal oxide or silicide layer.