High Density MIM Trench Capacitor Surface Area
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Solution Overview
Problem
As semiconductor devices shrink in size, the area available for metal-insulator-metal (MIM) capacitors decreases, leading to a loss of capacitance, necessitating higher capacitance structures to maintain performance in portable electronic devices.
Innovation Solution
The solution involves increasing the surface area of metal electrodes in MIM capacitors by forming isotropic ball shapes in trenches, using a method that includes depositing amorphous silicon and silicon dioxide bilayers, patterning with a hard mask, and etching to create concave surfaces, followed by depositing conducting and insulating layers to form high-density capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the area of semiconductor devices is decreased to meet consumer demand for smaller devices, then the portability and size of electronic devices is improved, but the area available for MIM capacitors decreases resulting in loss of capacitance
Solution Approach 1:
The patent applies spheroidality by forming isotropic ball shapes (spherical structures) within the trenches of the MIM capacitor. These spherical features increase the surface area of the metal electrodes without increasing the overall device footprint, thereby maintaining capacitance in smaller devices. The curved spherical geometry provides more surface area compared to flat planar structures of the same bounding box.
Solution Approach 2:
The patent transitions from two-dimensional planar capacitor structures to three-dimensional spherical structures within the trenches. By utilizing the third dimension (vertical depth of trenches and spherical curvature), the design increases electrode surface area and capacitance density without increasing the lateral footprint of the device.
2Volume of moving object
If conventional MIM capacitor structures are used in smaller devices, then the device size is reduced, but the capacitance performance deteriorates due to reduced electrode area and dielectric thickness
Solution Approach 1:
The isotropic ball shapes formed in the trenches create spherical metal electrode structures that maximize surface area within the constrained trench volume. This spherical geometry ensures that even in reduced-size devices, the capacitor maintains sufficient electrode area to deliver required capacitance performance, preventing performance deterioration.
Solution Approach 2:
The patent changes the geometric parameters of the capacitor structure by introducing spherical features with specific radius and curvature. By optimizing the radius of the isotropic balls and the depth of the trenches, the design achieves higher capacitance density that compensates for the reduced overall device size, maintaining performance 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
This approach results in higher capacitance density, allowing for smaller die sizes while maintaining or improving capacitance, suitable for applications in devices like mobile phones and Mirasol displays, by effectively increasing the surface area of the capacitor electrodes.
Implementation Method 1
Patterning the number of trenches includes isotropically etching the amorphous silicon layer to form the concave surfaces on the trenches
Implementation Method 2
depositing a first conducting layer on the trenches, depositing a first insulating layer on the first conducting layer; and depositing a second conducting layer on the first insulating layer
Data Source
AI summary
Higher capacitance density is achieved by increasing a surface area of a capacitor. A larger surface area may be obtained by forming isotropic ball shapes (a concave surface) in the trenches on the semiconductor die. The concave surfaces are fabricated by depositing bilayers of amorphous-silicon and silicon oxide. Openings are patterned in the silicon oxide hard mask for trenches. The openings are transferred to the amorphous-silicon layers through isotropic etching to form concave surfaces. Conducting, insulating, and conducting layers are deposited on the concave surfaces of the trenches by atomic layer deposition.