Recessed Metal Interconnects With Discontinuous Capping Layer
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Solution Overview
Problem
Conventional semiconductor interconnect structures with continuous dielectric capping layers have a shorter corner-to-corner distance between adjacent metal interconnects, increasing the probability of dielectric breakdown and reducing reliability.
Innovation Solution
The formation of recessed metal and liner interconnect features within an interlayer dielectric with a discontinuous capping layer, where the capping material and interlayer dielectric have coplanar surfaces, increasing the corner-to-corner distance and reducing the likelihood of dielectric breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous dielectric capping layer is used in conventional interconnect structures, then the manufacturing process is simpler, but the corner-to-corner distance between adjacent metal interconnects is shorter, increasing the probability of dielectric breakdown
Solution Approach 1:
The continuous capping layer is segmented into a discontinuous capping layer that is selectively formed only over the metal interconnect features. This segmentation increases the corner-to-corner distance between adjacent metal interconnects by exposing the dielectric material between them, thereby reducing the probability of dielectric breakdown while maintaining manufacturing feasibility through selective deposition processes.
Solution Approach 2:
The capping layer is applied with local quality differentiation - it is present over the metal interconnects to provide protection and planarization, but absent in the regions between adjacent interconnects. This localized application increases the effective corner-to-corner distance and reduces dielectric breakdown risk, while still maintaining the protective function where needed.
2Reliability
If metal interconnects are recessed below the dielectric surface, then the corner-to-corner distance is increased improving reliability, but additional processing steps are required
Solution Approach 1:
The metal interconnects are recessed below the dielectric surface before forming the discontinuous capping layer. This preliminary action of recessing creates the necessary geometry that allows the subsequent capping layer deposition to naturally form a discontinuous structure, increasing corner-to-corner distance and improving reliability without requiring complex post-processing steps.
Solution Approach 2:
The solution transitions from a two-dimensional planar capping layer to a three-dimensional discontinuous capping structure by recessing the metal interconnects vertically below the dielectric surface. This dimensional change allows the capping layer to be selectively positioned only where needed, increasing the effective distance between adjacent interconnects in the horizontal plane.
Data Source
AI summary
Interconnect structures and processes of fabricating the interconnect structures generally includes a recessed metal conductor and a discontinuous capping layer thereon. The discontinuous “capped” metal interconnect structure provides improved performance and reliability for the semiconductor industry.