TiN-SiN CMP Slurry Inhibitors for Barrier Layer Selectivity
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Solution Overview
Problem
Current chemical-mechanical polishing (CMP) compositions lack sufficient selectivity to reliably stop material removal at the barrier layer during the processing of advanced semiconductor devices, particularly in tungsten gate formation where undesired removal of the planar barrier layer can lead to lower gate heights.
Innovation Solution
A CMP composition comprising abrasive particles, a removal rate inhibitor with a polyoxyalkylene functional group and sulfonate or sulfate functional groups, and an aqueous carrier, which selectively removes the TiN layer faster than the SiN layer, achieving a TiN:SiN removal rate selectivity greater than 15:1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If typical CMP compositions are used for removing metal layers over TiN or SiN barrier layers, then the metal layer removal is achieved, but the selectivity between TiN and SiN is insufficient leading to undesired barrier layer removal
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific inhibitors and additives that alter the removal rates of TiN and SiN differently, thereby achieving the required selectivity while maintaining reliable gate height control
Solution Approach 2:
The patent introduces intermediary chemical agents (inhibitors and additives) that mediate the interaction between the CMP slurry and the barrier layers, enabling selective removal of TiN over SiN through differential chemical affinity and reaction mechanisms
2Productivity
If CMP polishing is performed to remove tungsten layer, then the metal layer removal rate is improved, but the barrier layer selectivity is insufficient causing planar portion removal
Solution Approach 1:
The patent adjusts chemical composition parameters including pH, oxidizing agents, and specific inhibitors to optimize both the removal rate of tungsten and the selectivity between TiN and SiN, achieving high productivity without sacrificing precision
Solution Approach 2:
The patent employs a composite CMP composition containing multiple functional components (abrasives, oxidizing agents, inhibitors, and additives) that work synergistically to achieve both high removal rate and high selectivity simultaneously
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 composition effectively controls the gate height by ensuring selective removal of the metal layer over the barrier layer, minimizing the risk of undesired barrier layer removal and achieving improved selectivity in CMP processes.
Implementation Method 1
a removal rate inhibitor selected from (I) a surfactant comprising a polyoxyalkylene functional group and a sulfonate functional group, (II) a surfactant comprising a polyoxyalkylene functional group and a sulfate functional group
Implementation Method 2
abrasive particles
Implementation Method 3
chemical-mechanical polishing composition
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition comprising (a) abrasive particles, b) a removal rate inhibitor selected from (I) a surfactant comprising a polyoxyalkylene functional group and a sulfonate functional group, (II) a surfactant comprising a polyoxyalkylene functional group and a sulfate functional group, (III) a first surfactant comprising a polyoxyalkylene functional group and a second surfactant comprising a sulfonate functional group, and (IV) a first surfactant comprising a polyoxyalkylene functional group and a second surfactant comprising a sulfate functional group, and (c) an aqueous carrier. The invention also provides a method of chemically-mechanically polishing a substrate comprising TiN and SiN with the inventive chemical-mechanical polishing composition.