Cup-Shaped DRAM Capacitor With High-k Support Layer
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Solution Overview
Problem
Dynamic random access memory (DRAM) capacitors face challenges in increasing capacitance while maintaining mechanical strength and density, as the close arrangement of memory cells limits horizontal expansion, necessitating vertical height increases which can compromise structural integrity.
Innovation Solution
A capacitor structure featuring a cup-shaped lower electrode, a high-k material top supporting layer, and a capacitor dielectric layer, which enhances mechanical strength, increases capacitor area and capacitance, and allows for mold stripping without a photomask, simplifying manufacturing and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of the capacitor is increased in the perpendicular direction to increase capacitor area and capacitance value, then the capacitance value is improved, but the mechanical strength and structural integrity deteriorate
Solution Approach 1:
The patent employs composite materials by integrating a top supporting layer made of high-k material (such as metal oxide) with the capacitor structure. This high-k material layer serves dual purposes: it provides mechanical support to prevent deformation and tipping of the tall capacitor structure, and it contributes to the capacitance value due to its high dielectric constant. This composite approach allows the capacitor to achieve high capacitance through vertical extension while maintaining structural integrity.
Solution Approach 2:
The top supporting layer is designed to perform multiple functions simultaneously: it acts as a mechanical support structure to prevent deformation and tipping, serves as part of the capacitor dielectric layer to increase capacitance, and provides structural stability for the vertical capacitor configuration. This multi-functionality resolves the contradiction by making the supporting structure itself contribute to the electrical performance.
2Productivity
If memory cells are closely arranged to increase density, then the productivity is improved, but the capacitor area available for increasing capacitance deteriorates
Solution Approach 1:
The patent transitions from horizontal capacitor area expansion to vertical capacitor area expansion by increasing the height of the capacitor structure in the perpendicular direction. This dimensional change allows the capacitor to achieve larger effective area and higher capacitance values while maintaining the same horizontal footprint, thereby enabling close arrangement of memory cells for high density without sacrificing capacitance.
3Ease of manufacture
If a traditional capacitor structure is used without a top supporting layer, then the manufacturing process is simpler, but the capacitor structure deforms or tips due to insufficient mechanical strength
Solution Approach 1:
The top supporting layer made of high-k material creates a composite structure that combines mechanical support functionality with dielectric functionality. This composite approach adds structural stability to prevent deformation and tipping of vertical capacitor structures while maintaining manufacturing feasibility through conformal deposition processes.
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 solution increases mechanical strength, capacitor area, and capacitance value while simplifying the manufacturing process and reducing costs by using a high-k material top supporting layer and eliminating the need for photomasks in the mold stripping step.
Implementation Method 1
The top supporting layer includes a high-k material. Surfaces of the cup-shaped lower electrode and the top supporting layer are covered by the capacitor dielectric layer.
Data Source
AI summary
Provided is a capacitor structure including a substrate, a cup-shaped lower electrode, a top supporting layer, a capacitor dielectric layer, and an upper electrode. The cup-shaped lower electrode is located on the substrate. The top supporting layer surrounds the upper portion of the cup-shaped lower electrode. The top supporting layer includes a high-k material. Surfaces of the cup-shaped lower electrode and the top supporting layer are covered by the capacitor dielectric layer. A surface of the capacitor dielectric layer is covered by the upper electrode.