CMP Slurry Composition for Fast Cobalt Film Polishing With Low Dishing
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) methods for semiconductor manufacturing using cobalt-containing films face challenges in achieving high polishing speed while minimizing dishing and ensuring the reliability of semiconductor products.
Innovation Solution
A polishing liquid comprising colloidal silica, specific compounds like glycine and iminodiacetic acid, passivation film forming agents, hydrogen peroxide, sodium, and ammonia, with controlled pH and mass ratios, is used in conjunction with a CMP method that involves a polishing pad and controlled pressure and liquid supply to enhance polishing efficiency and reduce dishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP methods are used for cobalt-containing films, then polishing can be performed, but polishing speed is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the polishing liquid by incorporating specific compounds (glycine, alanine, sarcosine, or iminodiacetic acid) combined with passivation film forming agents and controlled pH levels (5.5-8.0). This chemical parameter optimization enables significantly higher polishing speeds for cobalt-containing films while maintaining surface quality and semiconductor product reliability
Solution Approach 2:
The invention uses a composite polishing liquid formulation combining colloidal silica abrasives with specific organic compounds (amino acids or iminodiacetic acid), passivation film forming agents, hydrogen peroxide, and controlled sodium/ammonia ratios. This composite chemical system works synergistically to achieve high polishing speed without compromising reliability
2Productivity
If polishing is performed to achieve high polishing speed, then productivity increases, but dishing occurs on the polished surface
Solution Approach 1:
The patent optimizes the pH parameter to range 5.5-8.0 and controls the sodium to ammonia mass ratio within 1×10³ to 1×10⁶, creating chemical conditions that enable high polishing speed while preventing dishing. The specific compound concentrations and passivation agent selection are tuned to maintain surface flatness during high-rate polishing
Solution Approach 2:
The passivation film forming agents act as intermediaries that form protective films on the cobalt-containing film surface during polishing. These films prevent excessive material removal and dishing while allowing the polishing process to proceed at high speeds, mediating between the abrasive action and the workpiece surface
3Productivity
If polishing liquid composition is optimized for high polishing speed, then productivity improves, but chemical composition control complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges (pH 5.5-8.0, sodium to ammonia ratio 1×10³ to 1×10⁶, ClogP≥1.0) that define an optimized composition space. Within these ranges, high polishing speed is achieved without requiring ultra-precise control, balancing productivity improvement with manageable composition control 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 solution provides a balance of high polishing speed, reduced dishing, and improved reliability of semiconductor products by optimizing the chemical mechanical polishing process for cobalt-containing films.
Implementation Method 1
a polishing liquid used for chemical mechanical polishing of an object to be polished having a cobalt-containing film, the polishing liquid comprising: colloidal silica
Implementation Method 2
hydrogen peroxide
Implementation Method 3
one or more passivation film forming agents selected from the group consisting of a compound represented by General Formula (1) and a compound represented by General Formula (2)
Data Source
AI summary
The present invention provides a polishing liquid which has a good polishing speed and reduces the occurrence of dishing on a surface to be polished of an object to be polished having a cobalt-containing film after polishing in a case where the polishing liquid is applied to CMP of the object to be polished, and makes it possible to manufacture a semiconductor product having excellent reliability. The present invention also provides a chemical mechanical polishing method using the polishing liquid. The polishing liquid of an embodiment of the present invention is a polishing liquid used for chemical mechanical polishing of an object to be polished having a cobalt-containing film, the polishing liquid including colloidal silica, one or more specific compounds selected from the group consisting of glycine, alanine, sarcosine, and iminodiacetic acid, a passivation film forming agent, hydrogen peroxide, sodium, and ammonia, in which a mass ratio of a content of ammonia to a content of sodium is 1×103 to 1×106, and a pH is 5.5 to 8.0.