Multi-Layer MIM Capacitor Structure for Low Leakage Capacitance
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Solution Overview
Problem
Existing MIM capacitors suffer from large leakage current due to thin insulators, which limits their performance in integrated circuits and DRAM devices.
Innovation Solution
A capacitor device with a multi-layer dielectric structure is developed, where the insulating stack consists of alternating layers with different dielectric constants and lattice constants, forming a superlattice structure that exerts stress on the layers, resulting in a tetragonal or monoclinic crystal phase with enhanced dielectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a thin insulator is used in MIM capacitor, then capacitance is increased, but leakage current increases
Solution Approach 1:
The capacitor insulator is segmented into multiple thin dielectric layers (first dielectric layer, second dielectric layer, third dielectric layer) with different materials and properties. This segmentation allows each layer to contribute differently to the overall capacitance while distributing the electrical stress, thereby reducing leakage current compared to a single thin insulator layer.
Solution Approach 2:
The patent employs composite dielectric materials with different properties in each layer. The first dielectric layer has a first dielectric constant, the second dielectric layer has a second dielectric constant, and the third dielectric layer has a third dielectric constant. This composite structure optimizes the balance between capacitance and leakage current by combining materials with complementary characteristics.
2Productivity
If insulator thickness is reduced to increase capacitance, then device integration is improved, but reliability deteriorates due to increased leakage
Solution Approach 1:
The insulator is divided into multiple functional layers that can be independently optimized. The first dielectric layer provides high capacitance, the second dielectric layer provides stress control, and the third dielectric layer provides leakage reduction. This segmentation enables simultaneous achievement of high integration and reliability.
Solution Approach 2:
The patent changes multiple parameters including dielectric constant, layer thickness, and material composition across different layers. By optimizing these parameters independently for each layer, the structure achieves high capacitance density while maintaining low leakage current, thus improving both integration and reliability.
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 multi-layer dielectric structure provides a higher dielectric constant than a single bulk capacitor insulator, leading to increased capacitance while reducing leakage current due to smaller grain sizes and reduced grain boundaries.
Implementation Method 1
A dielectric constant and/or a lattice constant of the first layer are different than a dielectric constant and/or a lattice constant of the second layer. The first layers alternatingly stacked with the second layers form a superlattice multi-layer structure. In the superlattice multi-layer structure, a lowermost layer exerts a tensile or compressive stress on the overlying layers, so that the formed capacitor insulating stack has a monoclinic or tetragonal crystal phase.
Data Source
AI summary
Structures of a semiconductor device structure are provided. The semiconductor device structure includes a first insulating layer formed over a semiconductor substrate and an interconnect structure formed in the first insulating layer. The semiconductor device structure also includes a second insulating layer formed over the first insulating layer and a capacitor device embedded in the second insulating layer. The capacitor device includes a first capacitor electrode layer electrically connected to the interconnect structure, a capacitor insulating stack formed over the first capacitor electrode layer and a second capacitor electrode layer formed over the capacitor insulating stack. The capacitor insulating stack includes first layers alternatingly stacked with second layers. The dielectric constant of the first layer is different than the dielectric constant of the second layer.