Molybdenum Film Deposition with Seed Layer Underlayer Protection
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Solution Overview
Problem
Existing deposition methods for forming molybdenum films on semiconductor wafers cause damage to the underlayer due to exposure of the underlayer surface to reducing gases, leading to oxygen extraction and deterioration of the underlayer characteristics.
Innovation Solution
A deposition method involving the formation of a seed layer on the underlayer before applying a molybdenum-containing and reducing gas, using silicon-, boron-, or oxygen-containing gases to reduce the incubation time and minimize exposure to the reducing gas, thereby reducing oxygen extraction and film damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a molybdenum-containing gas and reducing gas are supplied directly to the underlayer, then the molybdenum film can be formed, but the underlayer surface is exposed to reducing gas causing oxygen extraction and deterioration of underlayer characteristics
Solution Approach 1:
A seed layer is formed on the underlayer surface before supplying the molybdenum-containing gas and reducing gas. This preliminary action creates a protective intermediate layer that prevents the reducing gas from directly contacting and damaging the underlayer, while still allowing the molybdenum film to be formed on top of the seed layer.
Solution Approach 2:
The seed layer acts as an intermediary between the underlayer and the molybdenum film formation process. It mediates the interaction by providing a surface for molybdenum deposition while protecting the underlying layer from harmful reducing gas exposure, thus resolving the contradiction between film formation and underlayer protection.
2Reliability
If the underlayer is exposed to reducing gas for a longer time, then more complete reduction reaction occurs, but oxygen extraction from the underlayer increases causing deterioration of underlayer characteristics
Solution Approach 1:
The seed layer is formed in advance to provide a reaction surface, which allows the reduction reaction to occur more efficiently and quickly on the seed layer surface rather than requiring prolonged exposure that would extract oxygen from the underlayer.
Solution Approach 2:
The seed layer serves as an intermediary reaction surface that enables complete reduction reactions to occur without requiring extended exposure times. The reduction reaction takes place on or near the seed layer interface, maintaining underlayer oxygen content while achieving reliable film formation.
3Device complexity
If no seed layer is formed, then the process is simpler and faster, but the incubation time increases and the underlayer is more exposed to reducing gas
Solution Approach 1:
Forming a seed layer as a preliminary step reduces the overall incubation time required for molybdenum film formation. Although this adds a process step, it accelerates the subsequent film deposition by providing a ready-made nucleation surface, thereby reducing total process time.
Solution Approach 2:
The introduction of a seed layer changes the surface properties and chemical composition at the deposition interface, which fundamentally alters the deposition kinetics. This parameter change enables faster film formation rates and reduces incubation time, offsetting the additional process step.
4Productivity
If fluorine-containing gas is used for molybdenum film formation, then the deposition process is efficient, but fluorine damage occurs to the underlayer and insulating film
Solution Approach 1:
The seed layer acts as a protective intermediary that shields the underlayer and insulating film from fluorine-containing gases during the molybdenum deposition process. This allows efficient fluorine-based deposition to proceed while preventing fluorine damage to underlying structures.
Solution Approach 2:
The seed layer is formed in advance to create a protective barrier before introducing fluorine-containing deposition gases. This preliminary protective measure enables the use of efficient fluorine-based chemistry without compromising the integrity of the underlayer and insulating film.
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 effectively reduces the incubation time and minimizes the exposure of the underlayer to reducing gases, preserving the underlayer's characteristics and preventing film damage, while using fluorine-free gases for molybdenum film formation.
Implementation Method 1
supplying a molybdenum-containing gas and a reducing gas to the substrate having the seed layer formed thereon, to form a molybdenum film on the seed layer
Implementation Method 2
the underlayer surface is exposed to the reducing gas, oxygen included in the underlayer may be extracted by the reducing gas
Data Source
AI summary
A film deposition method includes preparing a substrate having an insulating film formed thereon, forming a seed layer on the insulating film, and supplying a molybdenum-containing gas and a reducing gas to the substrate having the seed layer famed thereon, to foam a molybdenum film on the seed layer.