Semiconductor Film Deposition Sequence for 3D NAND Adhesion Control
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Solution Overview
Problem
As 3D NAND structures are miniaturized, there is a need to improve the characteristics of films such as tungsten and titanium nitride films used in NAND type flash memories to enhance adhesion and prevent diffusion of fluorine.
Innovation Solution
A method involving the supply of a Mo-containing gas, a reducing gas, and a reactive gas, followed by inert gas purging and atmosphere exhaustion, is applied to form films on substrates, with specific timing and repetition of these steps to improve film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If 3D NAND structures are miniaturized, then device density and integration are improved, but film characteristics such as adhesion and fluorine diffusion prevention deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the barrier film. Specifically, it forms a multi-layer barrier film with controlled ratios of different elements (such as Ti, Al, Si, N, O) to optimize both adhesion strength and fluorine diffusion prevention. The patent adjusts parameters like the atomic ratio of Ti to (Al+Si) in the range of 0.3-2.0, and controls the thickness of each layer to achieve the desired film characteristics for miniaturized devices.
Solution Approach 2:
The patent employs composite materials by creating a multi-layer barrier film structure combining different materials. The barrier film includes layers such as TiAlN, TiSiN, TiAlSiN, and TiO2 in various combinations. This composite structure leverages the complementary properties of each material: Ti provides adhesion, Al and Si enhance diffusion barrier properties, N contributes to film density, and O improves chemical stability. The multi-layer composite approach effectively addresses both adhesion and fluorine diffusion prevention requirements.
2Object-affected harmful factors
If TiN film is formed to prevent fluorine diffusion, then fluorine diffusion prevention is improved, but adhesion between W film and insulating film may be compromised
Solution Approach 1:
The patent applies local quality by creating a multi-layer barrier film where different layers perform different functions at different locations. The film structure includes an adhesion-enhancing layer (rich in Ti) in contact with the W film, intermediate layers (containing Al, Si, N) for fluorine diffusion prevention, and an insulating interface layer (TiO2) at the boundary with the insulating film. Each layer is optimized locally for its specific function, achieving both strong adhesion and effective fluorine diffusion prevention simultaneously.
Solution Approach 2:
The patent uses composite materials to create a multi-functional barrier film that simultaneously provides adhesion and fluorine diffusion prevention. The composite structure combines Ti-rich layers for adhesion, Al-Si-N containing layers for diffusion barrier properties, and TiO2 layers for chemical stability and insulating interface formation. This composite approach allows the barrier film to perform multiple functions that a single-material TiN film cannot achieve.
3Manufacturing precision
If complex gas supply sequences are used to improve film characteristics, then film quality is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the film formation process into distinct sequential steps, each with specific gas supply configurations. The process is segmented into: (1) supplying Mo-containing gas and reducing gas to form the base layer, (2) supplying reactive gas to modify the film structure, and (3) repeating these steps with controlled variations. This segmentation allows precise control over film characteristics while maintaining a systematic and manageable process flow that can be automated.
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 method enhances the adhesion and prevents fluorine diffusion, resulting in improved film characteristics for 3D NAND structures.
Implementation Method 1
performing (a-1) supplying a Mo-containing gas to a substrate, (a-2) supplying, to the substrate, a reducing gas that contains at least one among a borane-based gas, a phosphine gas and an active hydrogen-containing gas
Implementation Method 2
performing (a-3) exhausting an inner atmosphere of a space in which the substrate is accommodated; (e) before (a), performing a pre-processing of supplying an inert gas to the substrate for a predetermined time T1 and then exhausting the inner atmosphere of the space for a predetermined time T2
Data Source
AI summary
Described herein is a technique capable of improving characteristics of a film. According to one or more embodiments of the present disclosure, there is provided a technique that includes: (a) performing (a-1) supplying in parallel a metal-containing gas and a reducing gas that contains silicon and hydrogen and is free of halogen to a substrate in a process chamber, and (a-2) exhausting an inner atmosphere of the process chamber; (b) repeatedly performing (a) a first number of times; (c) supplying a nitrogen-containing gas to the substrate in the process chamber and exhausting the inner atmosphere of the process chamber after performing (b); and (d) repeatedly performing (a) a second number of times.