CMP Slurry Zoning for Mixed-Density Semiconductor Interconnects
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Solution Overview
Problem
Challenges arise in fabricating semiconductor devices with varying device densities due to inadvertent shortcomings during chemical mechanical polishing (CMP) processes, particularly when using oxidizing slurries, which affect the reliability of devices with higher densities in close proximity.
Innovation Solution
A method involving a series of CMP processes with tailored slurries and selective removal techniques to create uneven topographies, including dishing profiles and high-density dielectric layers, to manage redox reactions and prevent metal ion entrapment, ensuring reliable device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxidizing slurry is used in CMP process to remove materials, then material removal efficiency is improved, but devices with higher densities suffer from inadvertent shortcomings and reliability issues
Solution Approach 1:
The patent applies different CMP slurries to different regions of the substrate based on device density. High-density regions use a first slurry formulation while low-density regions use a second slurry formulation, allowing each region to be processed with optimal parameters for its specific characteristics, thus preventing reliability issues in high-density areas while maintaining removal efficiency
Solution Approach 2:
The patent segments the CMP process into multiple stages with different slurries. The first CMP process uses an oxidizing slurry for general material removal, while a second CMP process uses a different slurry formulation specifically for high-density regions, dividing the monolithic process into targeted segments that address specific regional needs
2Productivity
If devices with different densities are processed together in the same CMP process, then productivity is maintained, but devices with higher densities suffer from reliability shortcomings
Solution Approach 1:
The patent implements spatially varying slurry application where the slurry composition is tailored to the local device density. This allows simultaneous processing of different regions with different densities using region-specific slurry formulations, maintaining overall productivity while ensuring each region receives appropriate processing conditions
Solution Approach 2:
The patent introduces dynamic control into the CMP process by varying slurry parameters (such as oxidant concentration, pH, or composition) based on the spatial distribution of device densities across the substrate, allowing the process conditions to adapt to local requirements rather than using fixed uniform parameters
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 enhances the fabrication of semiconductor devices by reducing time-dependent dielectric breakdown and voltage breakdown, allowing simultaneous processing of features with different densities while maintaining device reliability.
Implementation Method 1
the conductive material is removed from the semiconductor substrate by performing a chemical mechanical polishing process utilizing a slurry that includes an oxidizer, wherein the conductive material is removed by redox reactions
Implementation Method 2
performing a chemical mechanical polishing process utilizing a slurry that includes an oxidizer, wherein the conductive material is removed by redox reactions
Data Source
AI summary
A semiconductor structure includes a contact over a substrate, an interlayer dielectric (ILD) layer including a first region disposed directly above the contact and a second region disposed adjacent to the first region, first conductive features embedded in the first region and separated by a first distance, a dielectric layer embedded in the ILD layer and disposed between the first conductive features in the first region, and second conductive features disposed in the second region and separated by a second distance greater than the first distance. The second region is free of the dielectric layer.