Conformal Molybdenum Film Deposition With Low Resistivity
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Solution Overview
Problem
There is a need for improved methods and materials to deposit conformal molybdenum films with lower resistivity, particularly for applications in advanced microelectronic devices with complex three-dimensional structures.
Innovation Solution
A method involving the conversion of an amorphous silicon layer to a metal layer by thermal soaking in the presence of a molybdenum or tungsten compound, followed by conformal deposition of a molybdenum film, which is performed in a continuous process without repetition, to achieve a thickness range of 10 to 50 Angstroms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CVD or ALD methods are used to deposit molybdenum films, then the deposition process can be performed, but the resulting films exhibit higher resistivity and poor conformality on three-dimensional structures
Solution Approach 1:
An amorphous silicon layer is deposited beforehand on the dielectric surface before the thermal soaking process. This preliminary silicon layer serves as a template that enables subsequent conformal metal atom replacement and ensures uniform molybdenum film deposition on complex three-dimensional structures, resolving both the resistivity and conformality issues
Solution Approach 2:
The invention changes the deposition parameters by using thermal soaking at elevated temperatures (400-600°C) to enable atom replacement reactions, rather than conventional low-temperature CVD or ALD. This parameter change allows metal atoms to replace silicon atoms conformally on vertical sidewalls, achieving both low resistivity and excellent conformality
2Reliability
If TiN liner films are deposited to achieve low resistivity molybdenum deposition, then resistivity is reduced, but the process complexity increases and conformality on high aspect ratio features is difficult to achieve
Solution Approach 1:
The invention extracts and eliminates the TiN liner film step from the deposition process. By using thermal soaking to directly form a metal layer from amorphous silicon, the process achieves low resistivity molybdenum deposition without requiring the additional TiN intermediate layer, thereby reducing process complexity while maintaining low resistivity
Solution Approach 2:
The thermal soaking process continuously replaces silicon atoms with metal atoms throughout the amorphous silicon layer in a single continuous operation. This continuous action forms the metal layer and enables subsequent conformal molybdenum deposition in one integrated process sequence, reducing the number of discrete steps compared to TiN liner approaches
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 results in molybdenum films with reduced resistivity, free of seams or voids, and improved conformality, enhancing the performance of microelectronic devices.
Implementation Method 1
converting the amorphous silicon layer to a metal layer by thermally soaking the amorphous silicon layer comprising silicon atoms in the presence of a metal compound
Implementation Method 2
at least a portion of the silicon atoms in the amorphous silicon layer are replaced by metal atoms selected from the group consisting of molybdenum atoms and tungsten atoms
Implementation Method 3
conformally depositing a molybdenum film on the metal layer
Data Source
AI summary
Conformally deposited molybdenum films having reduced resistivity and methods of forming the same are disclosed. The methods include converting an amorphous silicon layer to a metal layer by thermally soaking the amorphous silicon layer comprising silicon atoms in the presence of a metal compound selected from the group consisting of a molybdenum compound and a tungsten compound until at least a portion of the silicon atoms in the amorphous silicon layer are replaced by metal atoms selected from the group consisting of molybdenum atoms and tungsten atoms. The methods include conformally depositing a molybdenum film on the metal layer.