Tungsten Plug Contact Barrier for Low-Resistance Semiconductor Contacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor process nodes advance to smaller feature sizes, contact resistance issues arise due to reduced areas for contact plugs, particularly in tungsten plugs, necessitating improved methods to reduce resistance and enhance adhesion between tungsten plugs and conductive plugs while maintaining stability through thermal processes.
Innovation Solution
A method involving a blocking layer formed by electrostatic adsorption on tungsten plugs, followed by selective growth of a sidewall barrier and a thin bottom barrier to reduce contact resistance and improve adhesion, using a chemical composition of long-chain cationic compounds with specific solvent, surfactant, and pH buffer to prevent defects and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tungsten plugs are used for vertical electrical connections, then good electrical conductivity is achieved, but contact resistance increases as feature sizes are reduced to 28nm and below
Solution Approach 1:
The patent applies composite materials by combining tungsten plug with multiple barrier layers (first barrier layer, second barrier layer) and adhesive layers. This composite structure reduces contact resistance while maintaining the electrical conductivity of tungsten, resolving the contradiction between using tungsten for good conductivity and the increased contact resistance at smaller feature sizes.
Solution Approach 2:
The patent implements local quality by creating different barrier and adhesive layers at specific locations (interface between tungsten plug and conductive material, sidewalls) with distinct properties. The first barrier layer has different characteristics than the second barrier layer, and adhesive layers are placed only where needed at interfaces, optimizing local electrical and mechanical properties to reduce contact resistance.
2Object-affected harmful factors
If barrier layers are added to reduce contact resistance, then contact resistance decreases, but adhesion between tungsten plug and conductive plug deteriorates
Solution Approach 1:
The patent uses composite materials by creating a multi-layer structure including barrier layers and adhesive layers. The adhesive layers are specifically designed to bond the tungsten plug to the conductive plug, while barrier layers manage electrical properties. This composite approach simultaneously reduces contact resistance and maintains or enhances adhesion strength.
Solution Approach 2:
The patent introduces adhesive layers as intermediary materials between the tungsten plug and conductive plug. These adhesive layers act as mediators that provide strong bonding interfaces, ensuring that the addition of barrier layers for reducing contact resistance does not compromise the adhesion strength between dissimilar materials.
3Strength
If adhesive layers are added to improve adhesion, then adhesion strength increases, but contact resistance increases due to additional interface layers
Solution Approach 1:
The patent applies composite materials by combining adhesive layers with highly conductive barrier layers in a multi-layer structure. The adhesive layers provide necessary adhesion strength, while the barrier layers (first and second barrier layers) are designed with high electrical conductivity to minimize the resistance increase from additional interfaces. This composite structure balances adhesion and electrical conductivity.
Solution Approach 2:
The patent uses parameter changes by optimizing the thickness, material composition, and electrical conductivity parameters of the barrier layers. The first and second barrier layers are engineered with specific parameters to ensure high conductivity, compensating for the resistance introduced by adhesive layers, thus maintaining low overall contact resistance while achieving strong 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 method effectively reduces contact resistance and enhances adhesion between tungsten and conductive plugs, ensuring stability during thermal processes, while avoiding defects and oxidation, thus improving semiconductor performance.
Implementation Method 1
forming a blocking layer covering the upper surface of the tungsten plug by electrostatic adsorption
Data Source
AI summary
A semiconductor structure includes a semiconductor substrate, a dielectric layer, a tungsten plug, a conductive plug, and a contact barrier. The dielectric layer is over a semiconductor substrate. The tungsten plug is in the dielectric layer. The conductive plug is on the tungsten plug. The contact barrier includes a sidewall barrier on a sidewall of the conductive plug and a bottom barrier between the conductive plug and the tungsten plug. A thickness of the sidewall barrier is greater than a thickness of the bottom barrier.