Conformal Molybdenum Gap Fill on Dielectrics Without Seams or Voids
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Solution Overview
Problem
Current deposition techniques face challenges in achieving conformal and low resistivity molybdenum films on dielectric surfaces, particularly in high aspect ratio features and vias, where seams and voids can occur, affecting the electrical performance of microelectronic devices.
Innovation Solution
A method involving the formation of a nucleation layer on a dielectric surface using a molybdenum-containing precursor and nucleation reactant, followed by conformal deposition of a molybdenum film using atomic layer deposition or chemical vapor deposition, ensuring the film is substantially free of seams and voids, thereby improving film properties and reducing resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CVD or ALD methods are used to deposit molybdenum on dielectric surfaces, then the deposition process can be performed, but the resulting films exhibit high resistivity and poor conformality with seams and voids
Solution Approach 1:
The patent applies preliminary action by first depositing a thin nucleation layer (5-20 nm) of molybdenum on the dielectric surface before performing the main conformal deposition. This preliminary layer serves as a foundation that enables subsequent uniform and adherent molybdenum film growth, eliminating seams and voids that would otherwise form during direct deposition on dielectric surfaces.
Solution Approach 2:
The nucleation layer acts as an intermediary between the dielectric substrate and the main molybdenum film. This intermediate layer facilitates proper adhesion and provides a suitable surface for conformal deposition, resolving the contradiction between achieving low resistivity and maintaining film uniformity on dielectric surfaces.
2Strength
If TiN liner film is deposited on dielectric surface to achieve repeatable molybdenum deposition, then adhesion is improved, but the resistivity increases and conformality is compromised
Solution Approach 1:
The patent extracts the adhesion function from the TiN liner film approach and achieves it directly through the molybdenum nucleation layer deposited on the dielectric surface. By taking out the intermediate TiN layer, the patent eliminates the resistivity penalty while maintaining adhesion through the nucleation layer that provides both bonding to the dielectric and a suitable surface for subsequent molybdenum growth.
3Reliability
If gap fill applications use TiN deposition to achieve low resistivity and conformal deposition, then electrical properties improve, but the process complexity and manufacturing steps increase
Solution Approach 1:
The patent merges the functions of the TiN liner layer (adhesion) and the molybdenum film (conductive layer) into a single direct deposition process. By combining these functions into one step where molybdenum is deposited directly on the dielectric with the nucleation layer providing both adhesion and conductivity, the patent reduces process complexity while maintaining electrical performance.
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
The method achieves reduced resistivity of molybdenum films by up to 30% compared to conventional methods, providing improved uniformity and adhesion, and effectively fills high aspect ratio features without seams or voids, enhancing the electrical operation of integrated circuits.
Implementation Method 1
ALD employs chemisorption techniques to deliver precursor molecules on a substrate surface in sequential cycles
Implementation Method 2
The first and second precursors react to form a product compound as a film on the substrate surface
Implementation Method 3
conformally depositing a molybdenum film on the nucleation layer
Data Source
AI summary
Embodiments of the disclosure provide conformally deposited molybdenum films having reduced resistivity and methods of forming the same. The methods include forming a nucleation layer directly on a dielectric layer on a substrate surface by exposing the substrate surface to a molybdenum-containing precursor and a nucleation reactant, and conformally depositing a molybdenum film on the nucleation layer. Another aspect of the disclosure pertains to a method that is part of a gap fill process, comprising forming a nucleation layer directly on a dielectric region within one or more high aspect ratio gap features, including vertical gap features and/or horizontal gap features, and conformally depositing a molybdenum film on the nucleation layer to fill the feature.