AlN Crystal Separation Layer for Tungsten Interconnect Adhesion
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Solution Overview
Problem
In semiconductor devices, the formation of a suitable interconnect material layer is hindered by the presence of a titanium nitride barrier metal layer, particularly when trying to deposit a tungsten layer, due to adsorption issues and high stress leading to reduced adhesiveness and increased resistivity.
Innovation Solution
Incorporating a crystal separation layer, such as a metal oxide film or AlN film, between the barrier metal layer and the interconnect material layer, using alternating gas supply methods like ALD to reduce fluorine concentration and stress, thereby enhancing adhesiveness and reducing resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a titanium nitride barrier metal layer is used, then adhesion is improved, but the formation of a suitable tungsten interconnect material layer becomes difficult due to adsorption issues and high stress
Solution Approach 1:
An aluminum nitride (AlN) film is introduced as an intermediary layer between the titanium nitride barrier metal layer and the tungsten interconnect material layer. This AlN film serves as a mediator that prevents harmful fluorine adsorption from the tungsten deposition process onto the titanium nitride, while also managing stress to enable proper formation of the tungsten layer.
2Manufacturing precision
If alternating gas supply method is used to reduce fluorine concentration, then resistivity is reduced, but process complexity increases
Solution Approach 1:
The patent employs alternating gas supply during the tungsten layer formation process, switching between WF6 gas and H2 gas in periodic cycles. This periodic action controls fluorine concentration in the tungsten layer, achieving resistivity of 50 mΩ·cm or less while managing the process through systematic gas sequence control.
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 effectively reduces the resistivity of the interconnect material layer by 50% and ensures good adhesiveness, preventing fluorine diffusion and maintaining film quality, suitable for three-dimensional NAND flash memory applications.
Implementation Method 1
the aluminum nitride film has an effect of reducing a fluorine concentration in the tungsten layer
Implementation Method 2
forming a tungsten layer as an interconnect material layer on the aluminum nitride film by a physical vapor deposition method
Data Source
AI summary
In one embodiment, a semiconductor device includes a first insulator. The device further includes a metal layer that includes a first metal layer provided on a surface of the first insulator, and a second metal layer provided on a surface of the first metal layer and containing a first metallic element and oxygen or containing aluminum and nitrogen, or includes a third metal layer provided on the surface of the first insulator and containing a second metallic element, aluminum and nitrogen. The device further includes an interconnect material layer provided on a surface of the metal layer.