Hybrid-Height Metal Lines for RC Delay Reduction
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Solution Overview
Problem
As semiconductor technology advances, the increasing distance between adjacent metallization layers reduces parasitic capacitance but increases via resistance, while reducing this distance increases parasitic capacitance, making it difficult to simultaneously lower resistance and capacitance, which affects circuit performance.
Innovation Solution
The method involves forming metal lines of hybrid heights in low-resistance and low-capacitance regions, with larger heights in low-resistance regions to reduce via length and resistance, and lower heights in low-capacitance regions to increase distance and reduce parasitic capacitance, thereby forming air gaps between metal lines for reduced RC delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the distance between adjacent metallization layers is increased, then parasitic capacitance is reduced, but via resistance increases
Solution Approach 1:
The patent applies local quality by creating different metal line heights in different regions of the same metallization layer. Low-capacitance regions have reduced metal line heights to increase spacing and reduce parasitic capacitance, while low-resistance regions maintain standard heights to keep via resistance low. This spatial variation in structural properties resolves the contradiction by optimizing each region for its specific electrical requirements.
Solution Approach 2:
The patent introduces height variation as an additional dimensional parameter beyond the standard planar layout and fixed layer spacing. By controlling metal line height in the vertical dimension, the patent can independently adjust capacitance (affected by height) and via resistance (affected by via length) without changing the distance between adjacent metallization layers, thus resolving the contradiction through dimensional expansion.
2Reliability
If the distance between adjacent metallization layers is reduced, then via resistance is reduced, but parasitic capacitance increases
Solution Approach 1:
The patent applies local quality by creating different metal line heights in different regions of the same metallization layer. Low-capacitance regions have reduced metal line heights to increase spacing and reduce parasitic capacitance, while low-resistance regions maintain standard heights to keep via resistance low. This spatial variation in structural properties resolves the contradiction by optimizing each region for its specific electrical requirements.
Solution Approach 2:
The patent introduces height variation as an additional dimensional parameter beyond the standard planar layout and fixed layer spacing. By controlling metal line height in the vertical dimension, the patent can independently adjust capacitance (affected by height) and via resistance (affected by via length) without changing the distance between adjacent metallization layers, thus resolving the contradiction through dimensional expansion.
3Reliability
If metal line height is increased, then via resistance is reduced, but parasitic capacitance increases
Solution Approach 1:
The patent applies local quality by creating different metal line heights in different regions of the same metallization layer. Low-capacitance regions have reduced metal line heights to increase spacing and reduce parasitic capacitance, while low-resistance regions maintain standard heights to keep via resistance low. This spatial variation in structural properties resolves the contradiction by optimizing each region for its specific electrical requirements.
Data Source
AI summary
The present disclosure provides a semiconductor device. The semiconductor device includes a substrate comprising a device region, a first interconnect layer disposed over the device region, and a second interconnect layer disposed over the first interconnect layer. The first interconnect layer includes first metal lines and second metal lines. A height of the first metal lines is greater than a height of the second metal lines. A thickness of the first interconnect layer is different from a thickness of the second interconnect layer.