Landing Pad Patterning via Spacer Rounding
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Solution Overview
Problem
The reduction in size of DRAM components leads to denser capacitor contacts and landing pads, resulting in inconsistent shapes and undesired bridges between adjacent pads, complicating the fabrication process and reducing integration density and yield.
Innovation Solution
A patterning method involving sequential deposition of conductive and nitrogen/carbon-containing material layers on a substrate, followed by spacer formation and rounding processes to create uniform semiconductor structures, increasing integration density and process window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the critical size of DRAM is reduced to increase integration density, then the number of capacitor contacts and landing pads per unit area increases, but the shape consistency of landing pads deteriorates and undesired bridges form between adjacent pads
Solution Approach 1:
The patent divides the landing pad formation process into multiple patterning steps (first and second spacer formations, first and second mask patterns) to achieve precise control over landing pad shapes at reduced dimensions, thereby maintaining shape consistency while increasing integration density
Solution Approach 2:
The patent transitions from two-dimensional planar patterning to three-dimensional spacer-based patterning, using vertical spacer structures formed on sidewalls of mask patterns to define precise landing pad locations and shapes, enabling consistent formation at smaller critical sizes
2Quantity of substance
If the critical size of DRAM is reduced to increase integration density, then more capacitor contacts and landing pads fit in a smaller area, but undesired bridges form between adjacent landing pads
Solution Approach 1:
The patent performs preliminary spacer formation and rounding processes before final landing pad definition, pre-establishing precise geometric boundaries that prevent material encroachment and bridge formation between adjacent pads during subsequent fabrication steps
Solution Approach 2:
The patent introduces spacer structures as intermediary elements between mask patterns and final landing pads, using these spacers as self-aligned masks that precisely control material deposition and prevent unwanted connections between adjacent pads
3Quantity of substance
If the integration density of landing pad is increased, then more landing pads fit in a unit area, but the fabrication process becomes more complicated and process window decreases
Solution Approach 1:
The patent employs self-aligned spacer formation processes where spacers automatically form on sidewalls of mask patterns without requiring additional alignment steps, and subsequent etching steps self-correct to maintain precise geometric relationships, thereby simplifying the overall process despite increased density
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 method enhances integration density and process window while improving device yield by ensuring uniform shapes and preventing bridge formation between pads.
Implementation Method 1
A portion of the second carbon-containing material layer is removed by using the photoresist pattern as a mask
Implementation Method 2
A rounding process is performed to remove a portion of the second nitrogen-containing material layer, so as to form a second mask pattern
Data Source
AI summary
A patterning method includes sequentially forming a target layer, a first layer, a second layer, a third layer, and a first mask pattern. A first spacer is formed on a sidewall of the first mask layer. The first mask pattern is removed to form a plurality of peripheral openings surrounding a central opening in the first spacer. A rounding process is performed to round the peripheral openings and form a second mask pattern. A portion of the second layer is removed by using the second mask pattern as a mask, so as to form a third mask pattern. A second spacer is formed in the third mask pattern. The third mask pattern is removed. Portions of the first layer and the target layer are removed by using the second spacer as a mask.