Copper Interconnect Barrier Structure Using Self-Aligned Metal Oxide
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor device manufacturing lies in achieving a thin, uniform diffusion barrier layer for copper interconnects, as refractory metals used in damascene structures increase resistance and RC delay, while existing deposition methods like PVD face scalability issues and adhesion problems with low-k dielectric materials, leading to yield reduction and peeling of copper lines.
Innovation Solution
A method involving the formation of a conformal protective layer, such as cobalt or ruthenium, over copper-containing layers, followed by a thermal treatment to form a self-aligned metal oxide diffusion barrier layer, which reduces contact resistance and prevents conductor diffusion into the dielectric layer, thereby improving adhesion and reducing RC delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refractory metals (Ta, Ti, TaN) are used as diffusion barrier layer, then copper diffusion into dielectric is prevented, but resistance increases and RC delay increases
Solution Approach 1:
The patent uses a composite barrier structure consisting of a first barrier layer (refractory metal or nitride) and a second barrier layer (different material with lower resistance), creating a multi-material system that combines the diffusion-blocking capability of refractory metals with the low resistance properties of alternative materials, thereby resolving the contradiction between diffusion prevention and resistance reduction
Solution Approach 2:
The invention applies different materials with specific properties to different regions of the interconnect structure - the first barrier layer provides diffusion protection at the copper-dielectric interface, while the second barrier layer provides low-resistance conduction paths, optimizing local properties to simultaneously achieve diffusion prevention and resistance reduction
2Object-affected harmful factors
If PVD process is used to deposit thinner TaN/Ta barrier layer, then resistance is reduced, but adhesion to low-k dielectric deteriorates and copper lines peel off
Solution Approach 1:
The patent introduces an intermediary layer or modified interface structure between the refractory metal barrier and the low-k dielectric material that serves as a bonding mediator, improving adhesion strength while allowing the use of thinner barrier layers with lower resistance, thereby preventing copper line peeling
Solution Approach 2:
The invention modifies deposition parameters, layer thickness, or material composition to optimize the balance between resistance and adhesion, using controlled variations in process parameters to achieve both low resistance and strong adhesion simultaneously
3Manufacturing precision
If ALD process is used to deposit very thin diffusion barrier layer, then uniform coverage is achieved, but deposition rate is extremely low and throughput decreases
Solution Approach 1:
The patent divides the barrier structure into multiple layers (first barrier layer and second barrier layer) that can be deposited using different processes optimized for their respective requirements, allowing one layer to provide uniform coverage while another layer is deposited at higher rates, thereby segmenting the conflicting requirements
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 effectively decreases contact resistance and RC delay, enhances adhesion between the diffusion barrier layer and the IMD layer, and improves the yield of semiconductor devices by using a low-resistivity conformal protective layer and a self-aligned metal oxide barrier, addressing the limitations of refractory metals and existing deposition methods.
Implementation Method 1
performing a thermal process to form a metal oxide barrier layer underlying the metal-containing layer
Implementation Method 2
forming a conformal protective layer overlying the copper-containing layer... decreases contact resistance and RC delay
Data Source
AI summary
A method for forming an interconnect structure includes forming a dielectric layer overlying a substrate, forming an opening in the dielectric layer, forming a metal-containing layer overlying the opening in the dielectric layer, forming a conformal protective layer overlying the metal-containing layer, filling a conductive layer in the opening, and performing a thermal process to form a metal oxide layer barrier layer underlying the metal-containing layer.