Semiconductor Interconnect Layout for Lower Parasitic Capacitance
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Solution Overview
Problem
As semiconductor devices become more integrated, the area occupied by capacitors decreases, leading to a reduction in sensing margin due to increased parasitic capacitance, which is challenging to reduce with conventional dielectric materials having high dielectric constants.
Innovation Solution
The semiconductor device incorporates a method of fabricating metal wires of varying thicknesses, where a thinner first metal wire is coupled to a first transistor and a thicker second metal wire is coupled to a second transistor, with a capping layer and etching process to form the wires, thereby reducing capacitance and maintaining low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If dielectric materials with high dielectric constant are used in capacitors, then capacitor area can be reduced, but parasitic capacitance increases and sensing margin decreases
Solution Approach 1:
The patent applies local quality by forming metal wires with different thicknesses in different regions. Thinner metal wires are used in the memory cell region where low parasitic capacitance is critical for sensing margin, while thicker metal wires are used in the peripheral circuit region where low resistance is more important. This spatial differentiation of wire thickness optimizes both regions for their respective functional requirements.
Solution Approach 2:
The patent changes the physical parameter of metal wire thickness to control electrical properties. By varying the thickness parameter of metal wires, the patent simultaneously achieves low resistance (with thicker wires) and low parasitic capacitance (with thinner wires) in different locations, directly addressing the contradiction between these two electrical characteristics.
2Object-generated harmful factors
If metal wire thickness is reduced to lower parasitic capacitance, then sensing margin improves, but wire resistance increases
Solution Approach 1:
The patent resolves this contradiction by applying local quality - using thinner metal wires specifically in the memory cell region where low parasitic capacitance is essential, while using thicker metal wires in the peripheral circuit region where low resistance is prioritized. This localized differentiation allows each region to optimize for its primary requirement without compromising the other.
Solution Approach 2:
The patent segments the semiconductor device into distinct regions (memory cell region and peripheral circuit region) with different metal wire thickness specifications. This segmentation allows independent optimization of electrical characteristics in each region, enabling thin wires for low capacitance in memory cells and thick wires for low resistance in peripheral circuits.
3Reliability
If uniform thick metal wires are used throughout the device, then resistance is kept low, but parasitic capacitance increases and sensing margin deteriorates
Solution Approach 1:
The patent implements local quality by specifying different metal wire thicknesses for different functional regions. The memory cell region uses thinner metal wires to minimize parasitic capacitance and preserve sensing margin, while the peripheral circuit region uses thicker metal wires to maintain low resistance for robust signal driving capability.
Solution Approach 2:
The patent changes the metal wire thickness parameter based on location-specific requirements. By adjusting this physical parameter, the patent achieves optimal balance between resistance and capacitance in different regions, preventing the uniform thick wire design from causing excessive parasitic capacitance in sensitive memory cell areas.
Data Source
AI summary
A semiconductor device includes a substrate including a memory cell region and a peripheral circuit region, the peripheral circuit region including a first peripheral circuit region including a first transistor and a second peripheral circuit region including a second transistor; a storage node contact plug positioned in an upper portion of the substrate in the memory cell region; a landing pad over the storage node contact plug; a first metal wire coupled to the first transistor; and a second metal wire coupled to the second transistor, wherein a thickness of the landing pad and a thickness of the first metal wire are smaller than a thickness of the second metal wire.