Tapered Cylindrical Storage Node Prevents Bridging
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Solution Overview
Problem
Conventional methods for manufacturing cylindrical capacitors in semiconductor devices face challenges in preventing the leaning of storage nodes, which leads to bridging between adjacent nodes due to surface tension and increased height, making it difficult to maintain adequate cell-to-cell spacing and resulting in unstable capacitor formation.
Innovation Solution
The capacitor design features a cylindrical storage node with a tapered upper end portion, which increases the cell-to-cell spacing and prevents leaning, achieved through a manufacturing process involving the formation of a tapering layer with varying thicknesses and the use of specific materials like TiSix and ZrO2 layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a cylindrical storage node is formed to increase capacitance, then the node area is enlarged, but the storage node leans during drying causing bridging between adjacent nodes
Solution Approach 1:
A tapered layer is formed at the upper end portion of the cylindrical storage node before the dip-out process. This preliminary structural modification creates a tapered shape that prevents leaning during the subsequent drying procedure, thereby avoiding bridging between adjacent nodes while preserving the increased node area for high capacitance
Solution Approach 2:
The tapered layer is applied only to the upper end portion of the storage node, creating a localized structural difference. The lower portion maintains the cylindrical shape for maximum area, while the upper portion has the tapered shape for stability, combining the benefits of both geometries in different locations
2Reliability
If the height of storage nodes is reduced to prevent leaning, then bridging is prevented, but the capacitance is reduced
Solution Approach 1:
Instead of reducing height in the vertical dimension, the invention modifies the shape in the radial dimension by adding a tapered layer at the upper end portion. This creates an outward slope that increases stability without compromising the vertical height, thereby maintaining capacitance while preventing bridging
3Reliability
If cell-to-cell spacing is increased to prevent bridging, then storage node stability is improved, but the integration density is reduced
Solution Approach 1:
The invention changes the geometric parameters of the storage node by adding a tapered layer with specific thickness (50-500 Å at upper end, 10-100 Å at lower end). This parameter modification creates a self-stabilizing structure that prevents leaning, allowing maintenance of narrow cell-to-cell spacing while ensuring storage node stability
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 stabilizes the formation of cylindrical capacitors, increases production yield, and enables the creation of high-capacity semiconductor memory devices by preventing bridging between adjacent nodes and ensuring adequate spacing.
Implementation Method 1
a storage node could lean to cause bridging of two adjacent storage nodes due to the surface tension of deionized water (DIW) and the increased height of the storage node
Data Source
AI summary
A capacitor is made by forming a buffer oxide layer, an etching stop layer, and a mold insulation layer over a semiconductor substrate having a storage node contact plug. The mold insulation layer and the etching stop layer are etched to form a hole in an upper portion of the storage node contact plug. A tapering layer is deposited over the mold insulation layer including the hole. The tapering layer and the buffer oxide layer are etched back so that the tapering layer is remained only at the upper end portion of the etched hole. A metal storage node layer formed on the etched hole over the remaining tapering layer. The mold insulation layer and the remaining tapering layer are removed to form a cylindrical storage node having a tapered upper end. A dielectric layer and a plate node are formed over the storage node.