CMP Slurry Composition for Tungsten Planarity Control
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Solution Overview
Problem
Conventional chemical mechanical polishing compositions for tungsten etching in semiconductor manufacturing often cause recessing of tungsten vias, leading to electrical contact issues and increased non-planarity, due to their harsh chemical etching action, which is not effectively addressed by existing abrasive and Fenton's catalyst compositions.
Innovation Solution
A chemical mechanical polishing solution comprising a solvent, abrasive carbon-based particles with oxygen-containing functional groups and a Mohs hardness of at least 8, and soluble metal oxide anions such as vanadium, niobium, tantalum, chromium, molybdenum, or tungsten, which operates without Fenton's catalyst, providing controlled polishing and planarization of metal and metal nitride substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing compositions with Fenton's catalyst are used, then tungsten removal rate is improved, but tungsten recessing and loss of planarity occur
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by replacing Fenton's catalyst with soluble metal oxide anions (molybdic acid, tungstic acid, vanadic acid) and adjusting pH to a milder range (2-5), which reduces aggressive chemical etching while maintaining effective tungsten removal and planarity control
Solution Approach 2:
The patent introduces soluble metal oxide anions as intermediary substances that mediate between the abrasive particles and tungsten surface, providing controlled chemical reaction that converts tungsten to a soft oxidized film for easier mechanical removal without causing recessing
2Productivity
If harsh chemical etching is used to remove tungsten, then removal rate is improved, but electrical contact problems and via recessing occur
Solution Approach 1:
The patent modifies the chemical environment by using milder pH (2-5) and alternative oxidizing agents (metal oxide anions) that provide sufficient removal rate while preventing excessive etching that would compromise via integrity and electrical contact
Solution Approach 2:
The patent converts the harmful aggressive etching action into a beneficial controlled oxidation process, where soluble metal oxide anions provide just enough chemical action to facilitate mechanical removal without causing damage to via structure and electrical contacts
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 solution achieves effective removal rates of metals like cobalt, copper, molybdenum, and tungsten, with improved selectivity to dielectric layers, reducing static etch and maintaining planarity without the drawbacks of conventional methods.
Implementation Method 1
converting the tungsten to a soft oxidized film that is more easily removed from the surface by mechanical abrasion
Implementation Method 2
mechanical abrasion
Data Source
AI summary
The invention provides a chemical mechanical polishing solution for metal and metal nitride substrates comprising: a solvent; at least one abrasive with a Mohs hardness of at least 8; and at least one soluble metal oxide anion wherein the metal is selected from vanadium, niobium, tantalum, chromium, molybdenum and tungsten.