CMP Slurry Corrosion Inhibitor for Cobalt Polishing
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) slurries for cobalt (Co) and barrier films face challenges in achieving a high metal removal rate while minimizing corrosion, with existing neutral or near-neutral pH slurries still causing severe cobalt corrosion during the process.
Innovation Solution
The development of CMP compositions comprising at least one abrasive and a corrosion inhibitor represented by Formula (I): CmH2m+1—(OCH2CH2)n-L-R, where 6≤m≤20, n≥5, L is a bond or a specific linkage, and R is an anionic group, such as capryleth-9 carboxylic acid, along with a complexing agent like glycine, to inhibit corrosion and maintain a high Co removal rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high pH slurries are used, then corrosion is inhibited, but metal removal rate is limited
Solution Approach 1:
The invention changes the chemical parameters of the slurry by using neutral or near-neutral pH conditions combined with specific corrosion inhibitors (carboxylic acids, sulfonic acids, or phosphonic acids) and complexing agents. This allows achieving both corrosion inhibition and high metal removal rate by optimizing the chemical composition rather than relying on high pH alone.
Solution Approach 2:
The invention uses composite slurry compositions containing multiple components working together: abrasives (silica or alumina), corrosion inhibitors (carboxylic/sulfonic/phosphonic acids), and complexing agents (amino acids or amines). This composite approach enables simultaneous achievement of corrosion protection and high removal rate that single-component systems cannot achieve.
2Productivity
If low pH slurries are used, then metal removal rate is high, but severe corrosion occurs
Solution Approach 1:
The invention introduces corrosion inhibitors and complexing agents as intermediary substances that mediate between the acidic slurry environment and the metal surface. These intermediaries form protective layers or complexes that prevent direct corrosive attack while allowing controlled material removal, thus decoupling the relationship between low pH and severe corrosion.
Solution Approach 2:
The invention converts the potentially harmful acidic environment into a beneficial polishing condition by adding corrosion inhibitors that form protective films. The same acidic conditions that would normally cause severe corrosion are now harnessed to achieve high removal rates while the inhibitor converts the harmful effect into a controlled, beneficial material removal process.
3Object-affected harmful factors
If neutral pH slurries are used, then both corrosion performance and removal rate can be achieved, but conventional slurries still cause severe cobalt corrosion
Solution Approach 1:
The invention specifically targets cobalt corrosion by optimizing the pH range (6.0-8.0) and selecting corrosion inhibitors with appropriate pKa values and molecular structures. The use of specific carboxylic acids, sulfonic acids, or phosphonic acids with tailored chain lengths and functional groups provides selective protection against cobalt corrosion while maintaining effective material removal.
Solution Approach 2:
The invention employs composite slurry formulations specifically designed for cobalt, combining abrasives, corrosion inhibitors (carboxylic/sulfonic/phosphonic acids), and complexing agents (amino acids or amines). This composite approach provides enhanced cobalt-specific corrosion protection compared to conventional single-component slurries, achieving both reliability and performance.
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 effectively suppresses cobalt corrosion, achieving a Co removal rate greater than 2000 Å/min with a static etch rate of 20 Å/min or less at 50° C, resulting in a polished surface with minimal visible corrosion, suitable for high-performance microelectronic applications.
Implementation Method 1
the corrosion inhibitor comprises a compound represented by Formula (I): CmH2m+1—(OCH2CH2)n-L-R
Implementation Method 2
The chemical compositions of CMP slurries are critical to the performance of the metal CMP process. The slurries generally comprise abrasive(s) which provide mechanical abrasion action in the metal polishing
Data Source
AI summary
Provided herein are methods and compositions for chemical mechanical polishing (CMP) of metals. The present methods and compositions involve the use of a corrosion inhibitor having the general formula CmH2m+1—(OCH2CH2)n-L-R in the CMP slurry composition, where m is an integer between 6 and 11, inclusive of end points, and n is an integer greater than or equal to 6, L is a bond, —O—, —S—, —R1—, —S—R1—, or —O—R1—, where R1 is a C1-4 alkylene; and R is an anionic group. The present methods and compositions can be used to achieve a high metal removal rate, while effectively inhibiting metal corrosion during CMP, and are particularly useful for CMP of cobalt (Co).