Gate Contact Barrier Segmentation for Low Resistance Interconnects
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Solution Overview
Problem
As integrated circuit (IC) features sizes decrease and aspect ratios increase, existing contact features in multilayer interconnect structures face challenges with increased contact resistance and limited conductive material due to barrier layers, which restrict the efficiency of interconnect structures.
Innovation Solution
The method involves forming conductive multilayer interconnect features by reducing the amount of barrier layer material and using conductive materials like Ru and Co, which have lower resistivity, allowing for selective growth over the barrier layer without forming on sidewalls, thereby increasing the amount of conductive material deposited and reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier layers are implemented in multilayer interconnect structures, then adhesion and protection are improved, but contact resistance increases and conductive material amount is limited
Solution Approach 1:
The barrier layer is segmented into two distinct layers: a first barrier layer adjacent to the conductive feature and a second barrier layer adjacent to the interlayer dielectric. This segmentation allows each layer to be optimized for its specific function, with the first layer providing adhesion and the second layer providing protection, thereby reducing overall contact resistance while maintaining reliability.
Solution Approach 2:
Different regions of the barrier structure are assigned different material compositions and thicknesses. The first barrier layer has specific properties optimized for adhesion to the conductive feature, while the second barrier layer has properties optimized for protection against the interlayer dielectric. This local quality differentiation resolves the contradiction by allowing each region to perform its specific function optimally.
2Area of moving object
If feature sizes decrease, then integration density increases, but contact resistance increases due to barrier layer constraints
Solution Approach 1:
By dividing the barrier layer into two separate layers with different thicknesses and material compositions, the structure allows for greater flexibility in optimizing contact resistance as feature sizes decrease. The first barrier layer can be made thinner to reduce resistance, while the second layer maintains protective functions, enabling continued scaling without proportional increases in contact resistance.
3Manufacturing precision
If more conductive material is deposited, then contact resistance decreases, but barrier layer material limits the amount of conductive material that can be included
Solution Approach 1:
The segmented barrier layer structure creates more space for conductive material deposition. By making the first barrier layer thinner and optimizing the second barrier layer's position, the structure accommodates a greater volume of conductive material, thereby reducing contact resistance without requiring increases in feature size.
Solution Approach 2:
The invention changes the material parameters and thicknesses of the barrier layers to optimize conductive material deposition. By adjusting the composition and thickness of each barrier layer, the structure maximizes the amount of conductive material that can be effectively deposited while maintaining protective and adhesive functions.
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
This approach enhances the contact resistance of conductive multilayer interconnect features by allowing more conductive material to be deposited, improving the performance of IC devices by reducing resistance and increasing feature fillability.
Implementation Method 1
depositing a conductive material over the remaining portion of the barrier layer to form the second conductive feature
Implementation Method 2
depositing a conductive material over the remaining portion of the barrier layer to form the second conductive feature
Data Source
AI summary
A semiconductor structure includes a metal gate structure disposed over a semiconductor substrate, an interlayer dielectric (ILD) layer disposed over the metal gate structure, and a gate contact disposed in the ILD layer and over the metal gate structure, where a bottom surface of the gate contact is defined by a barrier layer disposed over the metal gate structure, where sidewall surfaces of the gate contact are defined by and directly in contact with the ILD layer, and where the barrier layer is free of nitrogen.