Self-Aligned Interconnect Structure Without Contact Barriers
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Solution Overview
Problem
As IC technologies progress towards smaller nodes, the reduction in critical dimensions of multilayer interconnect features leads to increased contact resistance, degrading IC device performance by increasing resistance-capacitance delay and posing challenges in manufacturing efficiency and cost.
Innovation Solution
The implementation of a barrier-free and self-aligned interconnect architecture that eliminates contact barriers, expands contact area, and achieves self-alignment between Mx and Vx layers, reducing contact resistance and capacitance while managing power consumption and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the critical dimensions of multilayer interconnect features are reduced to enable smaller IC nodes, then IC device density and integration are improved, but contact resistance increases and performance degrades
Solution Approach 1:
The patent removes the contact barrier layer from the interconnect structure, extracting the harmful element that causes high contact resistance. By eliminating the barrier layer entirely rather than attempting to reduce its resistance, the invention achieves lower contact resistance and improved signal routing efficiency in advanced technology nodes.
Solution Approach 2:
Instead of trying to reduce barrier layer thickness or improve barrier layer conductivity to manage contact resistance, the invention inverts the approach by completely removing the barrier layer. This unconventional solution transforms the problem from managing barrier layer properties to eliminating the barrier function entirely, achieving superior electrical contact.
2Reliability
If barrier layers are removed to reduce contact resistance, then electrical conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the metal layer formation process with the contact structure formation by depositing the metal layer conformally over the entire surface including contact regions, then performing a single etch step to define both metal interconnect features and contact holes simultaneously. This integration reduces the number of process steps and simplifies manufacturing while achieving the barrier-free contact structure.
Solution Approach 2:
The self-aligned etch process allows the contact holes to be automatically positioned relative to the metal features without requiring separate alignment steps. The conformal metal deposition and subsequent etch create inherent self-alignment, reducing manufacturing complexity while ensuring precise contact formation.
Data Source
AI summary
The present disclosure provides a method of forming a semiconductor structure. The method includes providing a semiconductor substrate and forming a patterned metal structure on the semiconductor substrate, wherein the patterned metal structure includes a first metal layer and a second metal layer deposited in a single deposition step. The method further includes etching a portion of the second metal layer thereby forming a metal plug in the second metal layer, the first metal layer of the patterned metal structure having a first metal feature underlying and contacting the metal plug.