Staggered Interconnection Structure for Lithography Feasibility
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Solution Overview
Problem
Scaling down interconnection structures in memory arrays to smaller minimum feature sizes is challenging due to lithography feasibility and material resistance issues, particularly with bitlines and bitline contacts.
Innovation Solution
An interconnection structure comprising two staggered rows of evenly spaced contact openings with conductive lines intersecting these rows, along with intermediate contacts that are part of a line array, which allows for relaxed critical dimensions and prevents undesirable shorts through strategic placement and material composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If interconnection structures are scaled down to smaller minimum feature sizes, then storage density increases, but lithography feasibility and contact edge taper become problematic
Solution Approach 1:
The contact structure is divided into multiple segments: a first contact portion extending in a first direction and a second contact portion extending in a second direction perpendicular to the first direction. This segmentation allows each portion to be optimized independently for lithography manufacturing, with the first contact portion having a larger critical dimension for easier patterning and the second contact portion providing the vertical connection path.
Solution Approach 2:
The contact structure transitions from a single-dimensional horizontal line to a two-dimensional L-shaped configuration by adding the second contact portion extending in the vertical direction. This dimensional change enables the contact to achieve both horizontal spacing for lithography feasibility and vertical connection functionality.
2Quantity of substance
If contact openings are made smaller to increase density, then storage capacity increases, but contact edge taper and fill material resistance increase
Solution Approach 1:
The contact is segmented into horizontal and vertical portions, allowing the fill material to be deposited and controlled separately in each direction. This segmentation enables better control over fill material distribution and reduces resistance by ensuring adequate filling in both dimensions without requiring excessively small opening sizes.
Solution Approach 2:
Different portions of the contact structure have different critical dimensions optimized for their specific functions: the first contact portion has larger dimensions optimized for fill material deposition and low resistance, while the second contact portion has dimensions optimized for vertical connection and structural integrity.
3Length of moving object
If critical dimensions are reduced to increase density, then miniaturization is achieved, but manufacturing complexity and short risks increase
Solution Approach 1:
The contact structure is segmented into two portions with different orientations and dimensions. The first contact portion extends horizontally with larger critical dimensions that are easier to manufacture, while the second contact portion extends vertically to provide the connection path, thereby reducing overall manufacturing complexity.
Solution Approach 2:
The first contact portion acts as an intermediary element that connects the underlying structure to the second contact portion. This intermediary structure with its larger critical dimensions simplifies the manufacturing process by providing a robust platform for forming the more critical vertical connection path.
Data Source
AI summary
An interconnection structure includes two staggered contact rows of evenly spaced contacts. Each contact row extends along a first direction. The interconnection structure further includes conductive lines extending along a second direction that intersects the first direction. The interconnection structure further includes intermediate contacts, where each intermediate contact is in contact with one of the contacts and one of the conductive lines.