Semiconductor Capacitor Composite Electrode Structure
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Solution Overview
Problem
As semiconductor devices become more integrated, the increased number of capacitors in a unit area leads to reduced layer thickness and increased aspect ratios, causing electrical and mechanical defects.
Innovation Solution
A semiconductor device design that includes a substrate with a conductive pattern, a lower electrode, a dielectric layer, a first upper electrode made of metal or metal nitride, a diffusion barrier formed by oxidizing the surface of the first upper electrode, and a second upper electrode made of a non-metallic conductive material, such as a silicon-based compound, to improve electrical and mechanical reliability by blocking impurity diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of capacitors in a unit area is increased to achieve higher integration, then the integration density is improved, but the layer thickness is reduced and aspect ratio is increased causing electrical and mechanical defects
Solution Approach 1:
The upper electrode uses a composite multi-layer structure consisting of a first upper electrode layer (metal or metal nitride), a diffusion barrier layer (formed by oxidizing the surface of the first upper electrode), and a second upper electrode layer (non-metallic conductive material such as silicon-based compound). This composite structure prevents impurity diffusion into the dielectric layer while maintaining electrical conductivity, thereby improving reliability without sacrificing integration density.
2Productivity
If the layer thickness is reduced to accommodate more capacitors, then the integration density is improved, but the electrical and mechanical defects increase
Solution Approach 1:
The multi-layer upper electrode structure with controlled thickness of each layer (first upper electrode layer, diffusion barrier layer, and second upper electrode layer) enables precise manufacturing even as overall capacitor dimensions are reduced for higher integration. The diffusion barrier layer specifically protects against impurity diffusion that becomes more problematic at reduced thicknesses.
3Productivity
If the aspect ratio of the capacitor is increased to fit more capacitors in a unit area, then the integration density is improved, but the electrical and mechanical defects increase
Solution Approach 1:
The composite upper electrode structure with the diffusion barrier layer provides mechanical stability and prevents impurity diffusion along the vertical path, which becomes more significant as aspect ratio increases. This maintains capacitor reliability even with higher aspect ratios required for dense integration.
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 enhances the high-k property of the dielectric layer, reducing leakage current and operational failures, and maintains electrical and mechanical reliability of the capacitor.
Implementation Method 1
a diffusion barrier formed on an upper surface of the first upper electrode
Implementation Method 2
A diffusion barrier may be formed by oxidizing a surface of the first upper electrode
Data Source
AI summary
A semiconductor device includes a substrate, a conductive pattern on the substrate, a lower electrode electrically connected to the conductive pattern, a dielectric layer covering a surface of the lower electrode, a first upper electrode on the dielectric layer, a diffusion barrier on an upper surface of the first upper electrode, and a second upper electrode covering the diffusion barrier, the second upper electrode including a different material from that of the first upper electrode.