Offset Contact Plug Layout for Short-Resistant IC Metal Wiring
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Solution Overview
Problem
The challenge in integrated circuit devices is to enhance the electrical reliability of metal wiring layers by reducing the likelihood of short-circuits between adjacent metal wiring structures, which becomes more critical as devices are miniaturized.
Innovation Solution
The proposed solution involves an integrated circuit device design that includes a lower insulating film, lower metal wiring layers, an upper insulating film, upper metal wiring layers, and conductive contact plugs. The conductive contact plugs have a specific geometry where the center of the uppermost portion is shifted in a particular direction relative to the center of the lowermost portion, which helps in increasing the separation distance between adjacent contact plugs and aligning them accurately with the lower metal wiring layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the line widths and pitches of metal wiring layers are reduced to enable device miniaturization, then the device size is reduced, but the electrical reliability deteriorates due to increased short-circuit risk between adjacent metal wiring structures
Solution Approach 1:
The contact plug is designed with an asymmetric structure where the upper portion has a larger width than the lower portion. Specifically, the upper width is configured to be greater than the lower width, creating a tapered or flared shape. This asymmetric geometry increases the separation distance between adjacent contact plugs at the upper level, thereby reducing short-circuit risk while maintaining compact device footprint
Solution Approach 2:
The invention addresses the two-dimensional packing density issue by introducing a dimensional variation in the vertical direction. By varying the width of the contact plug along its height (from lower width at the bottom to upper width at the top), the design utilizes the vertical dimension to achieve better electrical isolation without compromising the horizontal pitch requirements
2Reliability
If the center of the uppermost portion of the conductive contact plug is shifted from the center of the lowermost portion, then the separation distance between adjacent contact plugs is increased, but the alignment precision requirement increases
Solution Approach 1:
The asymmetric contact plug structure with shifted centers is designed in advance to preemptively increase separation distances. The upper portion's center is deliberately offset from the lower portion's center during the design stage, ensuring that even with standard manufacturing tolerances, adjacent contact plugs maintain sufficient clearance to prevent short-circuits
Solution Approach 2:
The invention changes the geometric parameters of the contact plug, specifically the width variation along the height and the lateral offset between upper and lower centers. By adjusting these parameters, the design achieves optimal balance between separation distance (for reliability) and alignment feasibility (for manufacturing)
Data Source
AI summary
An integrated circuit device includes: a lower insulating film arranged on a substrate; a lower metal wiring layer passing through the lower insulating film; an upper insulating film arranged on the lower insulating film and the lower metal wiring layer; an upper metal wiring layer arranged on the upper insulating film; and a conductive contact plug passing through the upper insulating film in a vertical direction and disposed between the lower metal wiring layer and the upper metal wiring layer, wherein a first center of an uppermost portion farthest from the substrate, of the conductive contact plug, is shifted in a first direction, which is parallel to a main surface of the substrate, from a second center of a lowermost portion closest to the substrate, of the conductive contact plug.