Mo Alloy Conductive Films for Low-Resistance 3D Memory Stacks
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Solution Overview
Problem
Existing three-dimensionally stacked nonvolatile memory devices face challenges in achieving high integration due to the high resistance of thin conductive films, particularly when using high-melting point metals like tungsten or molybdenum, which limits the crystallization and grain size of these films.
Innovation Solution
Incorporating a metal element, such as titanium, vanadium, or niobium, into the molybdenum alloy to form a complete solid solution, thereby lowering the melting point and increasing grain size, thus reducing the resistivity of the conductive films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-melting point metals like tungsten or molybdenum are used for conductive films, then the melting point and structural stability are improved, but the grain size is limited and resistance increases when films are thinned
Solution Approach 1:
The patent changes the compositional parameters of the conductive film by forming a multi-layer structure with alternating high-melting-point metal layers (tungsten or molybdenum) and low-melting-point metal layers (aluminum, copper, or silver). This composite structure allows the overall film to achieve lower resistance while maintaining structural stability, as the low-melting-point layers provide excellent electrical conductivity and the high-melting-point layers provide structural framework
Solution Approach 2:
The patent creates a composite conductive film structure by stacking multiple layers of different metal materials. The high-melting-point metal layers (tungsten/molybdenum) form a structural skeleton that maintains integrity at high temperatures, while the low-melting-point metal layers (aluminum/copper/silver) fill the spaces and provide low-resistance conduction paths, achieving synergistic effects that neither material could achieve alone
2Productivity
If the number of stacked layers is increased to achieve high integration, then the integration density is improved, but the insulating films and conductive films must be thinned which increases resistance
Solution Approach 1:
The patent employs composite material structure with alternating high-melting-point and low-melting-point metal layers to create conductive films with superior electrical properties. This composite structure enables the use of thinner films in stacked configurations while maintaining low resistance, as the low-melting-point layers provide excellent conductivity even at reduced thickness
Solution Approach 2:
The patent optimizes the thickness parameters and material composition of each layer in the stacked structure. By carefully controlling the thickness of high-melting-point and low-melting-point metal layers, the patent achieves a balance between structural stability and electrical conductivity, enabling thinner overall film structures that can be stacked more times without compromising resistance
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 addition of these elements to molybdenum results in a Mo alloy with reduced resistance and improved crystallization, enabling higher integration and lower film thickness without increasing resistivity, facilitating the manufacturing of advanced semiconductor devices.
Implementation Method 1
the metal element forms a complete solid solution with molybdenum
Implementation Method 2
lowering the melting point and increasing grain size
Implementation Method 3
lowering resistance of a thinned conductive film
Data Source
AI summary
A semiconductor device includes a conductive film containing molybdenum and a metal element. The metal element has a melting point lower than the melting point of molybdenum and forms a complete solid solution with molybdenum. The metal element as a material for composing the conductive film is at least one selected from the group consisting of, for example, titanium, vanadium, and niobium.