Semiconductor Barrier Layer Design for Copper Diffusion Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional diffusion barrier materials like Ta and TaN in semiconductor devices face challenges such as increased resistance, formation of weak spots, and oxidation, leading to copper diffusion into adjacent layers, which can cause device failures and RC delay.
Innovation Solution
A barrier layer comprising a nitride-based metal compound, such as HfN, combined with Ta or Ti, is formed using atomic layer deposition, providing improved diffusion prevention and oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thin conventional diffusion barriers (Ta or TaN) are used to prevent copper diffusion, then copper diffusion into adjacent layers is blocked, but the barriers form weak spots and holes that permit copper diffusion, causing device failures
Solution Approach 1:
The patent applies composite materials by combining multiple barrier layer materials (e.g., Ta and TaN, or CoFeB and TaN) into a multi-layer structure. This composite approach leverages the strengths of each material to achieve superior copper diffusion blocking while maintaining uniformity and avoiding weak spots that plague single-material thin barriers.
Solution Approach 2:
The patent segments the barrier layer into multiple distinct layers rather than using a single continuous layer. This segmentation allows each layer to perform specific functions (e.g., one layer for adhesion, another for diffusion blocking) and eliminates the formation of weak spots that occur in uniform thin barriers, thereby improving both reliability and manufacturing precision.
2Reliability
If Ta or TaN barrier layers are used, then copper diffusion is prevented, but these materials form oxide at the interface with insulating materials, increasing resistance and RC delay
Solution Approach 1:
The patent introduces an intermediary layer (such as CoFeB or other oxidation-resistant materials) between the Ta/TaN barrier layer and the insulating material interface. This intermediary layer prevents oxidation at the critical interface while maintaining the copper diffusion blocking function of the Ta/TaN layer, thereby eliminating the harmful oxidation effect without sacrificing diffusion prevention.
Solution Approach 2:
The patent changes the material parameter at the interface by selecting materials with different oxidation resistance properties. By positioning oxidation-resistant materials (CoFeB, Mo, W) at the interface with insulating materials, the patent fundamentally alters the chemical stability parameter at this critical location, preventing oxide formation and the associated resistance increase and RC delay.
3Object-affected harmful factors
If diffusion barriers are deposited in thin layers to avoid increasing resistance, then resistance increase is minimized, but weak spots and holes form that permit copper diffusion
Solution Approach 1:
The patent uses composite materials in a multi-layer barrier structure where each layer is optimized for specific thickness and function. This allows the overall barrier to remain thin enough to minimize resistance increase while the composite structure prevents weak spot formation, thereby simultaneously achieving low resistance and reliable copper diffusion prevention.
Solution Approach 2:
By segmenting the barrier into multiple thin layers rather than one thick layer, the patent achieves complete coverage without forming weak spots. Each segment can be precisely controlled in thickness to minimize resistance, while the collective segmented structure provides superior diffusion blocking compared to a single thin layer.
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 novel barrier layer effectively prevents copper diffusion and oxidation, maintaining low resistance and thermal stability, even at high temperatures, thus enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
diffusion barriers are sometimes used to prevent the diffusion of copper
Implementation Method 2
Ta and TaN barrier layers tend to form an oxide at the interface of some insulating materials
Data Source
AI summary
Semiconductor devices and methods of manufacture thereof are disclosed. A preferred embodiment comprises a method of forming a barrier layer. The method of forming the barrier layer includes providing a workpiece, forming a first material layer over the workpiece, the first material layer comprising a nitride-based metal compound. A second material layer is formed over the first material layer. The second material layer comprises Ta or Ti. The barrier layer comprises the first material layer and at least the second material layer.