Segmented Landing Areas for High Density Integrated Circuits
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Solution Overview
Problem
The challenge in integrated circuit fabrication is to reduce the pitch of landing areas for interlayer connectors without relaxing the pitch of parallel strips of material, which is limited by the resolution of photolithographic equipment, especially when using multiple patterning techniques.
Innovation Solution
The solution involves creating integrated circuits with strips of material having a first pitch and landing areas with a second pitch twice the first pitch, where the landing areas connect segments of strips in a specific pattern, allowing for tighter packing without increasing the pitch of the strips, using a self-aligned double patterning process and mask design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple patterning is used to reduce strip pitch, then strip density increases, but landing area pitch becomes greater than strip pitch
Solution Approach 1:
The landing areas are segmented into two alternating sets (first and second sets) that are offset from each other. This segmentation allows the landing areas to be formed using two separate patterning steps, each with relaxed pitch requirements, while the final landing area pattern achieves the required pitch relationship with the strips.
Solution Approach 2:
The first set of landing areas is formed in advance using a first patterning step with a pitch greater than the strip pitch. Then, the second set of landing areas is formed in a subsequent second patterning step. This preliminary action allows each patterning step to work with relaxed pitch constraints while achieving the final dense pattern.
2Manufacturing precision
If photolithographic resolution is increased to reduce minimum feature width, then equipment cost and complexity increase
Solution Approach 1:
The formation of landing areas is segmented into two separate patterning steps instead of attempting to form all landing areas in a single high-resolution step. This segmentation allows the use of lower-resolution, less complex photolithographic equipment for each individual patterning step while achieving the overall dense pattern through the combination of both steps.
3Quantity of substance
If landing area pitch is reduced to match strip pitch, then interlayer connector formation becomes difficult
Solution Approach 1:
Different regions of the landing area pattern are given different properties through the two-set structure. The first set of landing areas and the second set of landing areas are offset from each other, allowing interlayer connectors to be formed with relaxed pitch requirements in each local region while maintaining overall high density.
Data Source
AI summary
An integrated circuit comprises a plurality of strips of material over a substrate, the plurality of strips including strips S(i), each strip S(i) for i going from 3 to n having a first segment and a second segment separated by a gap from the first segment. The integrated circuit comprises a plurality of landing areas, the plurality of landing areas including landing areas A(i), each landing area A(i) for i going from 3 to n−2 connecting a first segment of strip S(i) in the plurality of strips with a second segment of strip S(i+2) in the plurality of strips, and disposed within the gap between the first and second segments in strip S(i+1). The strips S(i) have a first pitch in a direction orthogonal to the strips, and the landing areas A(i) have a second pitch twice the first pitch in the direction orthogonal to the strips of material.