Tetragonal Contact Plug Layout for Reliable IC Metal Wiring
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Solution Overview
Problem
The downscaling of integrated circuit (IC) devices has led to challenges in improving the electrical reliability of metal wiring structures, particularly in reducing contact resistance while minimizing the risk of short circuits between adjacent metal wiring structures.
Innovation Solution
The implementation of conductive contact plugs with a tetragonal shape, featuring specific sidewall orientations, to enhance electrical connectivity and spacing between metal wiring layers, thereby reducing contact resistance and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal wiring structures are downscaled to reduce linewidth and pitch, then device integration density is improved, but electrical reliability deteriorates due to increased contact resistance
Solution Approach 1:
The contact plug transitions from a conventional cylindrical shape to a tetragonal prism shape with vertical sidewalls. This dimensional change in geometry allows the contact plug to maximize its contact area with the metal wiring layer while maintaining a compact footprint, thereby improving electrical connectivity without increasing the lateral space occupied, which is critical for downscaled devices.
Solution Approach 2:
The invention changes the geometric parameters of the contact plug by defining specific sidewall orientations (first sidewalls perpendicular to the metal wiring layer, second sidewalls inclined relative to the metal wiring layer). This parameter optimization enables the contact plug to achieve both large contact area for low contact resistance and sufficient spacing from adjacent structures, resolving the reliability issue during downsaling.
2Reliability
If contact area is increased to reduce contact resistance, then electrical connectivity is improved, but the risk of short circuits between adjacent metal wiring structures increases
Solution Approach 1:
The contact plug employs asymmetric sidewall configurations where first sidewalls are perpendicular to the metal wiring layer and second sidewalls are inclined. This asymmetric design allows the contact plug to achieve maximum contact area with the metal wiring layer for low contact resistance while the inclined sidewalls naturally provide greater lateral spacing from adjacent metal wiring structures, reducing short circuit risk.
Solution Approach 2:
By changing from a cylindrical to a tetragonal prism shape with specifically oriented sidewalls, the contact plug optimizes its geometry to achieve both large contact area (improving connectivity) and adequate lateral spacing (reducing short circuit risk) simultaneously, resolving the contradiction between electrical connectivity and short circuit prevention.
Data Source
AI summary
An integrated circuit device includes a lower metal wiring layer, an upper insulating film and an upper metal wiring layer on the lower metal wiring layer, and a conductive contact plug passing through the upper insulating film in a vertical direction to contact the lower and upper metal wiring layers, and the conductive contact plug has a tetragonal planar shape. Each of first contact sidewalls of the conductive contact plug in a first lateral direction extends from a corresponding one of upper line sidewalls of the upper metal wiring layer to the lower metal wiring layer in the vertical direction, and at least one of a pair of second contact sidewalls of the conductive contact plug in a second lateral direction extends in a direction inclined with respect to the vertical direction from a bottom surface of the upper metal wiring layer toward the lower metal wiring layer.