Crown-Shaped Capacitor Fabrication via Nested Layers
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Solution Overview
Problem
As semiconductor memory devices, particularly DRAM devices, shrink in size, the development of capacitors to maintain or increase charge capacitance has lagged, leading to a need for methods to fabricate smaller capacitors with improved capacitance and structural strength.
Innovation Solution
A method for fabricating crown-shaped capacitors involves forming a protective pillar structure with sequential layers, including conductive and dielectric layers, and using sacrificial and protective pillars to support the structure during etching and deposition processes, preventing collapse and enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of capacitor in memory cell is reduced, then the memory cell size is reduced, but the charge capacitance is insufficient
Solution Approach 1:
The patent implements a crown-shaped capacitor structure where multiple capacitance layers (first capacitance layer, second capacitance layer, third capacitance layer) are nested concentrically around a central conductive contact. This nested arrangement allows the capacitor to maintain large effective capacitance area while occupying minimal planar space, directly resolving the contradiction between reduced capacitor size and sufficient charge capacitance.
Solution Approach 2:
The invention transitions from traditional planar capacitor layouts to a three-dimensional crown-shaped structure with multiple stacked capacitance layers. By utilizing the vertical dimension and creating concentric rings at different heights, the capacitor achieves increased capacitance density without proportionally increasing the footprint area, thereby maintaining small memory cell size while ensuring adequate charge storage capacity.
2Volume of moving object
If the capacitor size is reduced, then the memory cell size is reduced, but the structural strength is insufficient
Solution Approach 1:
The patent introduces a protective layer formed over the conductive contact and capacitance layers before subsequent etching and processing steps. This protective layer acts as a sacrificial structural support that maintains the integrity of the hollow crown-shaped structure during fabrication, preventing collapse before the final structure is completed.
Solution Approach 2:
The patent employs a sacrificial layer that is temporarily retained during fabrication to provide mechanical support to the hollow crown-shaped capacitor structure. This sacrificial layer acts as an intermediary support element that prevents structural collapse during processing, and is removed only after the capacitor structure has been fully formed and stabilized.
3Device complexity
If conventional fabrication methods are used, then the manufacturing process is simple, but the hollow structure collapses during processing
Solution Approach 1:
The patent forms a protective layer over the conductive contact and capacitance layers before etching the crown-shaped structure. This preliminary protective layer remains in place during subsequent processing steps, providing mechanical support to prevent collapse of the hollow structure, and is removed only after the capacitor is fully formed.
Solution Approach 2:
The sacrificial layer serves as a temporary intermediary support structure during fabrication. It is retained through multiple processing steps to maintain the structural integrity of the hollow crown-shaped capacitor, and is removed only after the capacitor structure has been completed and can stand independently.
Data Source
AI summary
A method for fabricating a crown-shaped capacitor includes providing a first dielectric layer with a protective pillar formed thereover, including a first conductive layer, a protective layer, and a mask layer. A second conductive layer is formed over a sidewall of the protective pillar. A first capacitance layer and a third conductive layer are formed over the first dielectric layer. A sacrificial layer is formed over the third conductive layer. The sacrificial layer, the third conductive layer, the first capacitance layer, the second conductive layer, and the mask layer above the protective layer are partially removed. The second conductive layer and the third conductive are removed to form a recess adjacent to the first capacitance layer. The protective layer is removed and an opening is formed to expose the first and second conductive layers. A second capacitance layer and a fourth conductive layer are formed in the opening. The sacrificial layer is removed to expose the third conductive layer.