Self-Aligned Diffusion Barriers for Copper Interconnects
Solution Overview
Problem
Copper wiring in microelectronic devices faces issues such as defects due to copper's interaction with silicon, increased capacitance, electrical shorts, and poor adhesion of diffusion barriers, leading to inefficiencies in signal transmission and device functionality.
Innovation Solution
A process involving the reaction of metals like manganese, chromium, or vanadium with insulator surfaces to form self-aligned diffusion barriers, using chemical vapor deposition without oxygen-containing co-reactants, and incorporating nitrogen to enhance adhesion and conductivity, while maintaining low electrical leakage and preventing copper diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional diffusion barrier layers (such as SiC, Si3N4, CoWP, CoWB, Mn) are used around copper wires, then copper diffusion is prevented, but dielectric constant increases leading to increased capacitance and reduced signal transmission speed
Solution Approach 1:
The patent changes the material composition parameters of the barrier layer by incorporating tungsten (W) and nitrogen (N) to form WNx compounds. This compositional modification allows the barrier to maintain copper diffusion prevention while achieving lower dielectric constant compared to traditional materials like Si3N4 or CoWP, thereby reducing capacitance and improving signal transmission speed.
Solution Approach 2:
The invention uses composite material WNx (tungsten nitride) that combines the barrier properties of tungsten with the low dielectric constant characteristics of nitrogen-containing compounds. This composite approach enables simultaneous achievement of copper confinement and reduced capacitance, resolving the contradiction between reliability and speed.
2Reliability
If electroless deposition of CoWP or CoWB is used to form barrier layers, then copper diffusion is blocked, but electrical shorts occur over insulators between copper wires
Solution Approach 1:
The patent changes the deposition method from electroless deposition to a controlled chemical vapor deposition or atomic layer deposition process for WNx. This parameter change in the fabrication method eliminates the formation of conductive pathways that cause electrical shorts, while maintaining the copper diffusion barrier function through the WNx material properties.
3Reliability
If barrier layers incorporating CoWP, CoWB, or Mn are used, then copper diffusion is prevented, but copper resistance increases due to incorporation of these materials
Solution Approach 1:
The patent optimizes the barrier layer thickness to ultrathin dimensions (1-5 nm) and uses WNx material with favorable electrical properties. This parameter optimization reduces the barrier's impact on copper conductivity while maintaining effective diffusion prevention, thereby minimizing resistance increase and energy loss.
4Reliability
If Mn is used to form barrier layers, then copper diffusion is blocked, but copper grain growth is restricted during anneal due to impurity presence
Solution Approach 1:
The patent substitutes Mn with WNx material, changing the chemical composition parameters. Tungsten nitride provides effective copper diffusion barrier properties without the harmful grain growth restriction effect caused by Mn impurities, allowing copper grains to grow properly during annealing processes and maintaining copper's electrical conductivity.
5Reliability
If MnOx is used as barrier layer, then copper diffusion is prevented, but adhesion to copper is poor
Solution Approach 1:
The patent changes the material from MnOx to WNx, optimizing the chemical composition and bonding characteristics. Tungsten nitride forms strong chemical bonds with copper substrate while maintaining effective diffusion barrier properties, thereby achieving both reliable copper confinement and strong interfacial adhesion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides robust, conductive, and durable copper interconnects with improved adhesion and barrier properties, enhancing the speed and longevity of microelectronic devices by preventing copper diffusion and corrosion.
Implementation Method 1
a conformal chemical vapor deposition (CVD) process that does not involve the use of any oxygen-containing co-reactant along with the precursor for Mn, Co, Cr or V
Implementation Method 2
the Mn, Co, Cr or V is delivered to the surfaces by a conformal chemical vapor deposition (CVD) process
Data Source
AI summary
An interconnect structure for integrated circuits for copper wires in integrated circuits and methods for making the same are provided. Mn, Cr, or V containing layer forms a barrier against copper diffusing out of the wires, thereby protecting the insulator from premature breakdown, and protecting transistors from degradation by copper. The Mn, Cr, or V containing layer also promotes strong adhesion between copper and insulators, thus preserving the mechanical integrity of the devices during manufacture and use, as well as protecting against failure by electromigration of the copper during use of the devices and protecting the copper from corrosion by oxygen or water from its surroundings. In forming such integrated circuits, certain embodiments of the invention provide methods to selectively deposit Mn, Cr, V, or Co on the copper surfaces while reducing or even preventing deposition of Mn, Cr, V, or Co on insulator surfaces. Catalytic deposition of copper using a Mn, Cr, or V containing precursor and an iodine or bromine containing precursor is also provided.