DRAM Capacitor Spacer Etching for Contact Margin
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Solution Overview
Problem
In dynamic random access memory (DRAM) devices, increasing capacitor height to achieve high integration leads to step differences, while reducing dielectric layer thickness increases leakage current, and existing methods to reduce bit line parasitic capacitance compromise the margin between storage node and bit line contacts.
Innovation Solution
A semiconductor device fabrication method involving the formation of a spacer along the contact hole, with selective etching to expose and remove the spacer, ensuring a sufficient margin between bit line and storage node contacts, while maintaining capacitance and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of the capacitor is increased to achieve high integration, then the capacitance is improved, but the step difference increases causing manufacturing difficulties
Solution Approach 1:
The patent transitions from planar capacitor structures to vertically stacked capacitor structures, moving the capacitance enhancement to the vertical dimension. Multiple capacitor layers are stacked above each other, allowing capacitance to be increased without expanding the horizontal chip area or creating excessive step differences that would complicate manufacturing.
Solution Approach 2:
The patent implements nested capacitor structures where multiple capacitor elements are stacked and integrated within a compact vertical space. Each capacitor layer is nested within the structure of the previous layer, maximizing capacitance density while maintaining a relatively low overall profile that minimizes step differences.
2Quantity of substance
If the thickness of the dielectric layer is decreased to increase capacitance, then the capacitance is improved, but the leakage current increases
Solution Approach 1:
The patent employs composite dielectric materials consisting of multiple layers with different properties. By combining materials with high dielectric constants and low leakage characteristics in a layered composite structure, the patent achieves high capacitance without the increased leakage current that would result from simply thinning a single dielectric layer.
Solution Approach 2:
The patent applies different dielectric materials with optimized properties to different regions and layers of the capacitor structure. Each layer is selected with specific local qualities - some layers prioritize high dielectric constant for capacitance, while others prioritize low leakage characteristics, creating a differentiated structure that simultaneously achieves high capacitance and low leakage.
3Area of stationary object
If the margin between storage node contact and bit line contact is reduced for high integration, then the chip area is reduced, but the reliability decreases
Solution Approach 1:
The patent resolves the contact margin problem by transitioning from a two-dimensional lateral arrangement to a three-dimensional vertical arrangement. Storage node contacts and bit line contacts are positioned at different vertical levels and depths, allowing their horizontal projections to overlap or be closely spaced without risking electrical interference, thus maintaining reliability while reducing chip area.
Solution Approach 2:
The patent introduces spacer structures as intermediary elements between the storage node contact and bit line contact. These spacers act as physical barriers and electrical isolators that prevent direct interaction between the contacts, allowing them to be positioned closer together horizontally while maintaining adequate electrical isolation 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
This method improves product reliability by securing a necessary margin between contacts, addressing the integration challenges and leakage current issues in DRAM devices.
Implementation Method 1
etching the spacer having a different etching selectivity from the substrate structure and the conductive layer
Data Source
AI summary
A method for manufacturing the semiconductor device may include forming a capping layer including a bit line contact hole on a substrate, forming a spacer on inner walls of the bit line contact hole, forming a bit line contact in the bit line contact hole, forming a bit line layer on the substrate, exposing the spacer by etching the bit line layer, and etching the spacer.