DRAM Drain Contact Trench Layout for Lower Contact Resistance
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Solution Overview
Problem
The shrinking dimensions of microelectronic device features, such as DRAM cells, lead to increased contact resistance due to smaller contact structures, which adversely affects device performance by decreasing drive current.
Innovation Solution
A method of forming microelectronic devices involves creating spacer structures with specific cross-sectional shapes and masking layers to selectively remove isolation structures and form contact trenches, resulting in contact structures with increased horizontal dimensions, thereby reducing contact resistance and enhancing drive current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dimensions of microelectronic device features are reduced to increase integration density, then the level of integration or density of features is improved, but the contact resistance increases due to smaller contact structures
Solution Approach 1:
The patent extends the contact structure in the lateral direction (horizontal dimension) rather than increasing vertical height. The contact structure includes a first portion and a second portion that laterally overlap with the drain region, effectively increasing the contact area in the planar dimension to reduce contact resistance while maintaining feature density.
Solution Approach 2:
The contact structure is divided into multiple segments: a first contact structure portion and a second contact structure portion, which are positioned at different lateral locations relative to the drain region. This segmentation allows the contact structure to wrap around or extend along the drain region, increasing total contact area without increasing the footprint of individual contact points.
2Quantity of substance
If the dimensions of contact structures are reduced to match smaller feature sizes, then the integration density is improved, but the drive current decreases due to increased contact resistance
Solution Approach 1:
The contact structure utilizes lateral extension in the horizontal plane rather than vertical height increase. By extending the contact structure to laterally overlap with the drain region, the patent increases the effective contact area in the planar dimension, thereby reducing contact resistance and improving drive current while maintaining compact vertical profiles.
Solution Approach 2:
The contact structure is segmented into first and second portions that can be positioned at different lateral locations. This segmentation enables the contact structure to wrap around or extend along the drain region, maximizing the total contact area and improving current flow paths without increasing the overall device footprint.
Data Source
AI summary
A method of forming a microelectronic device comprises forming a spacer structure having a rectangular ring horizontal cross-sectional shape over a transistor, a portion of the spacer structure horizontally overlapping a drain region of the transistor. A masking structure is formed over the spacer structure and the transistor, the masking structure exhibiting an opening therein horizontally overlapping the drain region of the transistor and the portion of the spacer structure. A portion of an isolation structure overlying the drain region of the transistor is removed using the masking structure and the portion of the spacer structure as etching masks to form a trench vertically extending through the isolation structure to the drain region of the transistor. A drain contact structure is formed within the trench in the isolation structure. Microelectronic devices, memory devices, and electronic systems are also described.