CMP Polishing Liquid Composition for Low-Scratch Cobalt Films
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Solution Overview
Problem
Existing polishing liquids for chemical mechanical polishing (CMP) using cobalt as a wiring line metal element in semiconductor manufacturing suffer from erosion and scratches on the polished surface, which are not adequately addressed by existing technologies.
Innovation Solution
A polishing liquid comprising colloidal silica, an organic acid, a nitrogen-containing aromatic heterocyclic compound with a C log P value of less than 1.0, hydrogen peroxide, and a pH of 8.5 to 12, optionally with surfactants and specific ratios of sodium and potassium, is used to reduce erosion and scratches during CMP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a polishing liquid with pH 4.0 or less is used for CMP of cobalt-containing films, then the polishing process can proceed, but erosion and scratches occur on the polished surface
Solution Approach 1:
The patent changes the pH parameter from acidic (≤4.0) to basic (8.5-12.0) to fundamentally alter the chemical environment during polishing. This parameter change enables the use of hydrogen peroxide as an effective corrosion inhibitor for cobalt while maintaining polishing efficiency, thereby resolving the contradiction between productivity and surface quality
Solution Approach 2:
The patent introduces hydrogen peroxide as an intermediary substance that mediates between the polishing particles and the cobalt-containing film. Hydrogen peroxide acts as a corrosion inhibitor that prevents erosion and scratches by controlling the chemical interaction at the interface, allowing effective polishing without surface damage
2Ease of manufacture
If conventional polishing liquids are used for cobalt CMP, then polishing can be performed, but corrosion potential differences cause harmful effects on the cobalt film
Solution Approach 1:
The patent changes the pH parameter to a basic range (8.5-12.0) which fundamentally alters the corrosion behavior of cobalt. This parameter change eliminates the harmful corrosion effects that occur in acidic environments while maintaining polishing feasibility
Solution Approach 2:
Hydrogen peroxide is introduced as a corrosion inhibitor that mediates the interaction between the polishing liquid and cobalt film. It controls the corrosion potential and prevents harmful chemical reactions, enabling safe polishing of cobalt-containing films
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 proposed polishing liquid effectively minimizes erosion and scratches on cobalt-containing films, enhancing the quality of the polished surface in semiconductor manufacturing.
Implementation Method 1
The polishing liquid comprises hydrogen peroxide
Implementation Method 2
The polishing liquid comprises colloidal silica
Data Source
AI summary
A polishing liquid which reduces the occurrence of erosion and scratches 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 is provided. In addition, a chemical mechanical polishing method using the above-mentioned polishing liquid is provided. The polishing liquid is a polishing liquid used for chemical mechanical polishing of an object to be polished having a cobalt-containing film. The polishing liquid includes colloidal silica, an organic acid, a specific nitrogen-containing aromatic heterocyclic compound and hydrogen peroxide, and has a pH of 8.5 to 12.