DRAM Bit Line Titanium Nitride Barrier
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Solution Overview
Problem
During the fabrication of bit lines in dynamic random access memories (DRAMs), metal atoms often diffuse between layers, causing current leakage due to the scaling down of these devices, which affects their integration and density.
Innovation Solution
A method involving the formation of a nitrogen-containing titanium silicide/titanium silicide layer by depositing a titanium nitride layer between the conductive silicon and titanium layers, using a burn-in process with nitrogen and inert gases to prevent titanium diffusion, and subsequent thermal processing to form a nitrogen-containing titanium silicide/titanium silicide layer that prevents current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal layers are deposited to form bit line structure, then electrical conductivity is improved, but metal atom diffusion between layers occurs causing current leakage
Solution Approach 1:
A nitrogen-containing titanium silicide layer is introduced as an intermediary barrier layer between the titanium layer and conductive silicon layer. This intermediate layer prevents direct contact and diffusion between titanium atoms and silicon atoms, thereby eliminating current leakage while maintaining the electrical conductivity function of the bit line structure
Solution Approach 2:
The invention uses a composite material structure consisting of multiple layers including titanium nitride, titanium, and nitrogen-containing titanium silicide. The combination of these materials creates a bit line structure that simultaneously achieves electrical conductivity through titanium and diffusion prevention through the nitrogen-containing titanium silicide barrier layer
2Productivity
If device scaling is performed to increase integration and density, then manufacturing capacity is improved, but metal diffusion between layers increases causing current leakage
Solution Approach 1:
The bit line structure is segmented into multiple functional layers: a titanium layer for electrical conductivity, a nitrogen-containing titanium silicide layer for diffusion prevention, and a conductive silicon layer for signal transmission. This segmentation allows each layer to perform its specific function independently, enabling device scaling while preventing metal diffusion
Solution Approach 2:
The nitrogen-containing titanium silicide layer serves as a mediator that enables the bit line structure to achieve both high integration density through scaling and reliable current leakage prevention by blocking diffusion pathways between adjacent metal and silicon layers
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 prevents titanium diffusion into the conductive silicon layer, thereby reducing current leakage and enhancing the reliability and performance of DRAMs by maintaining the integrity of the bit line structure.
Implementation Method 1
introducing nitrogen gas and inert gas into the chamber, and ionizing the nitrogen gas and the inert gas to form nitrogen ions and inert ions
Implementation Method 2
The nitrogen ions and inert ions bombard the titanium target to form a first titanium nitride layer
Implementation Method 3
a thermal process is performed to transform the titanium nitride layer into a nitrogen-containing titanium silicide layer
Implementation Method 4
react both the second titanium nitride layer and the titanium layer with the conductive silicon layer to form a nitrogen-containing titanium silicide/titanium silicide layer
Data Source
AI summary
A fabricating method of a semiconductive element includes providing a substrate, wherein an amorphous silicon layer covers the substrate. Then, a titanium nitride layer is provided to cover and contact the amorphous silicon layer. Later, a titanium layer is formed to cover the titanium nitride layer. Finally, a thermal process is performed to transform the titanium nitride layer into a nitrogen-containing titanium silicide layer.