Method for forming titanium nitride barrier with small surface grains in interconnects
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Solution Overview
Problem
The existing glue layers in back-end-of-line integrated circuit fabrication fail to effectively restrict the diffusion of elements like tungsten and copper, leading to poor electrical connections between semiconductor devices due to high density of grain boundaries and reduced carbon content.
Innovation Solution
A glue layer with isolated lattices uniformly distributed in an amorphous region is formed using a low-power plasma operation, increasing carbon content and improving the ability to restrict element diffusion, while maintaining appropriate conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional glue layer is used in the back-end-of-line process, then the fabrication process is simple, but the diffusion of elements like tungsten and copper cannot be effectively restricted
Solution Approach 1:
The glue layer is segmented into multiple sub-layers with different carbon contents. The first sub-layer has a first carbon content while the second sub-layer has a second carbon content different from the first. This segmentation creates distinct functional zones that effectively restrict element diffusion while maintaining electrical connectivity.
Solution Approach 2:
Different regions of the glue layer are assigned different carbon contents to optimize local properties. The first sub-layer with its specific carbon content provides certain diffusion barrier properties, while the second sub-layer with different carbon content provides complementary properties, creating a locally optimized structure for element restriction.
2Reliability
If the carbon content in the glue layer is reduced, then the lattice structure becomes more dense, but the ability to restrict element diffusion decreases
Solution Approach 1:
The carbon content parameter is varied across different sub-layers of the glue layer. By changing the carbon content from the first sub-layer to the second sub-layer, the patent optimizes the balance between lattice density and element diffusion restriction capability, achieving effective barrier properties without requiring uniformly low carbon content throughout.
Solution Approach 2:
The glue layer is constructed as a composite structure with multiple sub-layers having different carbon compositions. This composite approach combines materials with different carbon contents to achieve superior element diffusion restriction compared to a homogeneous layer, leveraging the complementary properties of each sub-layer.
3Productivity
If a plasma operation with high power is performed to form the glue layer, then the deposition speed is fast, but the carbon content decreases and grain boundaries increase
Solution Approach 1:
The plasma operation is performed periodically with controlled timing and power levels to deposit different sub-layers with specific carbon contents. By using periodic plasma exposure rather than continuous high-power plasma, the patent maintains adequate carbon content while achieving the desired multi-layer structure for effective element diffusion restriction.
Solution Approach 2:
Plasma operation parameters such as power level, gas flow rates, and exposure time are changed between deposits of different sub-layers. These parameter changes allow control over the carbon content in each sub-layer, enabling the formation of a multi-layer structure that restricts element diffusion while maintaining production efficiency.
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 solution effectively restricts element diffusion and maintains proper conductivity, ensuring reliable electrical connections between semiconductor devices by optimizing the carbon content and lattice structure of the glue layer.
Implementation Method 1
performing a plasma operation on the titanium nitride layer to form a plurality of isolated lattices
Data Source
AI summary
A method of forming a semiconductor device, comprising: forming a first conductive layer on an active device of a substrate; forming a dielectric layer on the first conductive layer; forming a through hole passing through the dielectric layer to expose a portion of the first conductive layer; conformally depositing a glue layer in the through hole to cover the portion of the first conductive layer comprising: forming a plurality of isolated lattices in an amorphous region at which the isolated lattices are uniformly distributed and extend from a top surface of the glue layer and terminate prior to reach a bottom of the glue layer, wherein the glue layer has a predetermined thickness; depositing a conductive material on the glue layer within the through hole, thereby forming a contact via; and forming a second conductive layer on the contact via over the first conductive layer.