Dual-Orientation DRAM Capacitor Electrode for Lower Leakage
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Solution Overview
Problem
In DRAM devices, the integration of capacitor structures leads to increased leakage current due to the thickness reduction of upper electrodes, which affects the electrical characteristics and reliability of the device.
Innovation Solution
A capacitor structure is designed with a lower electrode, a dielectric pattern on its sidewall, and an upper electrode structure comprising two sequentially stacked electrodes made of metal nitride, where the first upper electrode has a different crystal orientation and a higher work function than the second upper electrode, reducing leakage current and lowering overall resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of the upper electrode is reduced to increase integration, then the device density is improved, but the leakage current increases
Solution Approach 1:
The upper electrode is divided into two separate electrodes with different crystal orientations. The first upper electrode has a high work function crystal orientation to reduce leakage current, while the second upper electrode has a low work function crystal orientation to maintain low resistance. This segmentation allows each electrode to optimize for its specific function rather than requiring a single electrode to compromise between conflicting requirements.
Solution Approach 2:
Different regions of the upper electrode structure are given different local properties through crystal orientation control. The first upper electrode region is engineered with high work function crystal orientation specifically for leakage reduction at the dielectric interface, while the second upper electrode region is engineered with low work function crystal orientation for conductivity. This local quality differentiation resolves the contradiction by applying the right property in the right location.
2Object-generated harmful factors
If the work function of the upper electrode is increased to reduce leakage current, then the leakage current is reduced, but the resistance increases
Solution Approach 1:
The upper electrode function is segmented into two separate electrodes: the first upper electrode with high work function crystal orientation handles leakage current reduction, while the second upper electrode with low work function crystal orientation handles resistance management. This functional segmentation eliminates the need for a single electrode to simultaneously optimize for both conflicting properties.
Solution Approach 2:
The upper electrode structure uses a composite configuration of two metal nitride layers with different crystal orientations. This composite structure combines the beneficial properties of high work function materials (leakage reduction) and low work function materials (low resistance) in a single integrated electrode assembly, achieving both goals simultaneously.
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 configuration enhances the electrical characteristics of the capacitor structure by reducing leakage current and achieving a lower resistance, thereby improving the performance and reliability of the DRAM device.
Implementation Method 1
a work function of the first upper electrode is greater than a work function of the second upper electrode
Implementation Method 2
the metal nitride included in the first upper electrode has a crystal orientation that is different from a crystal orientation of the metal nitride included in the second upper electrode
Data Source
AI summary
A capacitor structure includes a lower electrode; a dielectric pattern on a sidewall of the lower electrode; and an upper electrode structure, the upper electrode structure including a first upper electrode and a second upper electrode sequentially stacked on a sidewall of the dielectric pattern, wherein each of the first upper electrode and the second upper electrode includes a metal nitride, and the metal nitride included in the first upper electrode has a crystal orientation that is different from a crystal orientation of the metal nitride included in the second upper electrode, and a work function of the first upper electrode is greater than a work function of the second upper electrode.