Cobalt CMP Slurry Composition for Selective Removal and Corrosion Control
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving superior planarization of nanostructures with cobalt barrier films, requiring tunable removal rates and selectivity between metal and dielectric materials while minimizing corrosion and erosion, particularly at the Co/Cu interface.
Innovation Solution
A CMP slurry composition comprising nano-sized colloidal silica particles, specific chemical additives, and an oxidizing agent like hydrogen peroxide, along with corrosion inhibitors and pH adjusters, is used to achieve tunable Co film removal rates, low static etch rates, and reduced galvanic corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional barrier materials like tantalum or titanium are used, then established CMP processes can be applied, but cobalt-specific issues such as galvanic corrosion and different electrochemical properties cannot be addressed
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific corrosion inhibitors (benzotriazole, mercaptobenzothiazole, ethylenediaminetetraacetic acid) and oxidizing agents (hydrogen peroxide) to address the electrochemical incompatibility between cobalt and traditional slurry formulations, thereby preventing galvanic corrosion while enabling effective cobalt polishing
Solution Approach 2:
The patent introduces corrosion inhibitors as intermediary substances that mediate between the cobalt barrier material and the CMP slurry environment, forming protective complexes with metal ions and reducing direct corrosive interactions, thus enabling reliable cobalt processing without requiring changes to the base slurry composition
2Productivity
If aggressive chemical composition is used to achieve high removal rates, then cobalt film removal rate increases, but static etch rate increases leading to more corrosion defects
Solution Approach 1:
The patent converts the potentially harmful aggressive chemical action into a beneficial process by using controlled oxidation with hydrogen peroxide to activate cobalt removal while simultaneously employing corrosion inhibitors to neutralize excessive etching, thus transforming what would be harmful high reactivity into a controlled, efficient, and safe polishing process
Solution Approach 2:
The patent optimizes the concentration parameters of chemical additives, maintaining oxidizing agent levels sufficient for high removal rates while precisely controlling corrosion inhibitor concentrations to suppress static etch rate and corrosion defects, achieving a balanced chemical environment that supports both productivity and quality
3Adaptability or versatility
If tunable removal rate is achieved through composition adjustment, then selectivity between cobalt and dielectric can be optimized, but formulation complexity increases
Solution Approach 1:
The patent achieves multi-functionality by selecting corrosion inhibitors and additives that simultaneously perform multiple roles: benzotriazole and mercaptobenzothiazole provide both corrosion inhibition and dispersancy, while hydrogen peroxide serves as both oxidizing agent and pH buffer, thereby enabling tunable removal rates and selectivity without proportionally increasing formulation complexity
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 provides high and tunable Co film removal rates, selective removal of dielectric films, minimized corrosion, and reduced defects, effectively addressing the challenges of planarization and corrosion in cobalt-based semiconductor processing.
Implementation Method 1
an oxidizing agent, typically hydrogen peroxide
Implementation Method 2
an abrasive comprising nano-sized particles selected from the group consisting of silica, alumina, ceria, germania, titania, zirconia
Implementation Method 3
Mechanical action is usually carried out by a polishing pad
Implementation Method 4
a corrosion inhibitor selected from the group consisting of 1,2,3-triazole, 1,2,4-triazole, 1,2,3-benzotriazole, 5-methylbenzotriazole, benzotriazole
Data Source
AI summary
Cobalt barrier Chemical Mechanical Planarization (CMP) compositions, systems and methods are provided for the removal of cobalt or a cobalt alloy from the surface of a semiconductor device during its manufacture. The compositions use suitable chemical additives selected from the group consisting of an aliphatic organic carboxylic acid, an aromatic organic carboxylic acid, and combinations thereof; abrasives; an oxidizing agent; and an corrosion inhibitor; to provide tunable cobalt film removal rates, tunable selectivity between cobalt and dielectric or other barrier films, and maintain very low static etching rates on cobalt film.