CMP Polishing Liquid Composition for Stable Silicon Nitride Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polishing liquids exhibit a large variation in polishing rate and do not meet the accuracy requirements for CMP treatments, particularly when polishing silicon nitride or polysilicon, necessitating a solution with a higher polishing rate and reduced variability.
Innovation Solution
A polishing liquid comprising colloidal silica, an organic acid with a phosphonic acid group or its salt, hypophosphorous acid, and water, with specific pH and particle diameter ranges, along with optional additives like phosphonic acid, phosphoric acid, surfactants, and pH adjusters, is used in chemical mechanical polishing to enhance polishing efficiency and reduce rate variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing liquids are used for CMP treatment, then the polishing process can be performed, but the polishing rate exhibits large variation and does not meet accuracy requirements
Solution Approach 1:
The patent changes the chemical parameters of the polishing liquid by introducing hypophosphorous acid and specific organic acids (phosphonic acid, carboxylic acid) in controlled concentrations. The pH is precisely adjusted to 2.5-5.0, and the content of hypophosphorous acid is controlled at 1.0×10^-8 to 1.0×10^-5% by mass. These parameter changes stabilize the chemical action on silicon nitride and polysilicon surfaces, reducing polishing rate variation while maintaining high polishing efficiency.
Solution Approach 2:
The patent creates a composite polishing liquid system combining colloidal silica (abrasive component) with multiple chemical components: hypophosphorous acid, phosphonic acid, carboxylic acid, and water. This composite formulation synergistically combines mechanical abrasion with controlled chemical etching, where each component contributes to stabilizing the polishing rate on different materials (silicon nitride and polysilicon), thereby improving overall manufacturing precision.
2Productivity
If conventional polishing liquids are used, then the process is simple, but the polishing rate is not high enough to meet modern semiconductor manufacturing demands
Solution Approach 1:
The patent optimizes chemical parameters including pH (2.5-5.0), hypophosphorous acid concentration (1.0×10^-8 to 1.0×10^-5% by mass), and organic acid concentrations to simultaneously achieve high polishing rate and high precision. The specific pH range enhances chemical reactivity with silicon nitride and polysilicon while the controlled acid concentrations prevent excessive etching, thus improving productivity without sacrificing manufacturing precision.
3Manufacturing precision
If the polishing liquid contains multiple chemical components, then the polishing performance improves, but the formulation becomes more complex
Solution Approach 1:
The patent defines specific parameter ranges for each chemical component to achieve optimal performance: pH 2.5-5.0, hypophosphorous acid at 1.0×10^-8 to 1.0×10^-5% by mass, phosphonic acid at 0.01-10% by mass, and carboxylic acid at 0.1-10% by mass. These quantified parameters provide clear formulation guidelines that balance improved polishing precision with manageable formulation complexity, enabling consistent reproduction of the polishing liquid's 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 provides a high polishing rate with minimal variation, particularly for silicon nitride and polysilicon, improving the accuracy and consistency of CMP treatments.
Implementation Method 1
the surface of the substrate is flattened by the chemical action of the polishing liquid and the generated mechanical friction
Implementation Method 2
a polishing liquid containing abrasive particles
Implementation Method 3
the surface of the substrate is flattened by the chemical action of the polishing liquid and the generated mechanical friction
Data Source
Figure 1
AI summary
An object of the present invention is to provide a polishing liquid that has a high polishing rate and exhibits a small variation in polishing rate in a case where polishing is carried out using the polishing liquid. The polishing liquid of the present invention is a polishing liquid for use in chemical mechanical polishing, containing colloidal silica, an organic acid having at least a phosphonic acid group or a salt thereof in a molecular structure, hypophosphorous acid, and water.