Alkaline CMP Composition for Co and TiN/TaN Removal Control
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) compositions for semiconductor substrates fail to provide adequate control over the material removal rate (MRR) of cobalt, titanium nitride (TiN), and tantalum nitride (TaN), leading to corrosion and material deterioration due to acidic pH values and inadequate TiN:TaN ratio control.
Innovation Solution
A CMP composition comprising potassium persulfate as an oxidizer, with a pH range of 8.5 to 11.0, including inorganic particles, an organic compound with an amino and/or acid group, a corrosion inhibitor, and an aqueous medium, which maintains a TiN:TaN MRR ratio between 0.5 and 2.0, minimizing corrosion and material damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acidic pH CMP composition is used, then copper and cobalt polishing rate is improved, but corrosion and material deterioration occurs
Solution Approach 1:
The patent changes the pH parameter from acidic to alkaline range (pH 9.0-11.0) to resolve the contradiction. This parameter change allows the CMP composition to achieve adequate polishing rates for copper and cobalt while eliminating the corrosion and material deterioration problems associated with acidic compositions. The alkaline pH environment prevents copper and cobalt dissolution while maintaining effective material removal through the synergistic chemical-mechanical action.
2Productivity
If high removal rate for Co and Ti/TiN and/or Ta/TaN is achieved, then polishing efficiency is improved, but TiN:TaN ratio control becomes difficult
Solution Approach 1:
The patent employs parameter changes in the oxidizer system (using potassium persulfate instead of hydrogen peroxide, adjusting oxidizer concentration to 0.1-5.0 wt%) and pH (9.0-11.0) to simultaneously achieve high removal rates for cobalt and Ti/TiN and/or Ta/TaN while maintaining precise TiN:TaN ratio control (0.5-2.0). The alkaline environment combined with the specific oxidizer enables selective and controlled material removal.
Solution Approach 2:
The patent introduces specific intermediary substances including organic compounds with amino and/or acid groups (0.1-5.0 wt%), corrosion inhibitors (0.01-1.0 wt%), and chelating agents (0.01-1.0 wt%) that mediate between the oxidizer and the metal surfaces. These intermediaries facilitate controlled chemical reactions that enable high removal rates while maintaining precise TiN:TaN ratio control through selective complexation and surface modification.
3Reliability
If cobalt is used as adhesion layer, then copper electroplating is improved, but dissolution in acidic oxidizing solution occurs
Solution Approach 1:
The patent changes the pH parameter to alkaline range (9.0-11.0) which fundamentally alters the chemical behavior of cobalt. In this alkaline environment, cobalt maintains its adhesion properties and enables effective copper electroplating while resisting dissolution that occurs in acidic oxidizing solutions. The alkaline pH prevents cobalt ion formation and subsequent dissolution, preserving the adhesion layer integrity.
Solution Approach 2:
The patent introduces corrosion inhibitors (0.01-1.0 wt%) and chelating agents (0.01-1.0 wt%) as intermediary substances that specifically protect the cobalt adhesion layer. These intermediaries form protective complexes with cobalt surface, preventing direct contact between the oxidizer and cobalt metal, thereby eliminating dissolution while preserving adhesion functionality and enabling subsequent copper electroplating.
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 achieves better control over MRR of Co, TiN, and TaN with reduced corrosion and material deterioration, preventing TiN or TaN dishing or protrusion, and maintaining a stable TiN:TaN ratio, thus enhancing the polishing process in the semiconductor industry.
Implementation Method 1
potassium persulfate as an oxidizer
Implementation Method 2
inorganic particles
Data Source
AI summary
The presently claimed subject matter is directed to a chemical mechanical polishing (CMP) composition comprising inorganic particles, at least one organic compound comprising an amino group and/or at least one acid group (Y), potassium persulfate, at least one corrosion inhibitor and an aqueous medium for polishing substrates of the semiconductor industry comprising cobalt and/or a cobalt alloy and TiN and/or TaN.