Polishing Agent Polymer Selectivity Silicon Oxide Nitride
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) technologies face challenges in achieving high selectivity between silicon oxide and silicon nitride films, leading to insufficient planarization and increased risk of polishing-induced scratches due to abrasive grain aggregation.
Innovation Solution
A polishing agent comprising abrasive grains, a water-soluble polymer copolymerized from unsaturated dicarboxylic acid and ethylenic double bond-containing monomers, and water, which inhibits abrasive grain aggregation and enhances selectivity by adsorbing onto both the silicon nitride surface and abrasive grains, thereby controlling the polishing rate and preventing scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing agents are used, then polishing can be performed, but selectivity between silicon oxide and silicon nitride films is insufficient leading to polishing-induced scratches
Solution Approach 1:
A water-soluble polymer is introduced as an intermediary substance in the polishing agent. This polymer selectively adsorbs onto the silicon nitride film surface, forming a protective layer that prevents abrasive grains from directly contacting and scratching the stopper film. The polymer acts as a mediator between the abrasive grains and the silicon nitride film, enabling high selectivity while preventing harmful scratching effects.
Solution Approach 2:
The polishing agent utilizes controlled pH parameters (maintained between 4-9) to optimize the adsorption characteristics of the water-soluble polymer onto the silicon nitride film. By adjusting and maintaining specific pH conditions, the polymer's adsorption affinity is enhanced, improving selectivity. Additionally, the polymer concentration and molecular weight are optimized to achieve maximum protective effect while maintaining high polishing rate of silicon oxide.
2Manufacturing precision
If high selectivity is achieved through existing polishing agents, then silicon nitride film protection is improved, but abrasive grain aggregation occurs causing scratches
Solution Approach 1:
The water-soluble polymer serves a dual intermediary function: it adsorbs onto silicon nitride to protect it, and simultaneously adsorbs onto abrasive grain surfaces to prevent grain aggregation. This dual-mediated interaction ensures that abrasive grains remain dispersed and do not clump together, eliminating the scratching caused by aggregated grains while maintaining high selectivity.
Solution Approach 2:
The polishing agent formulation optimizes polymer concentration (0.01-5% by weight) and molecular weight (1,000-100,000) to achieve optimal dispersion of abrasive grains. The pH parameter is controlled (4-9) to maximize polymer adsorption on both silicon nitride and abrasive grains, preventing aggregation. These parameter optimizations ensure uniform abrasive grain distribution throughout the polishing process.
3Productivity
If polishing speed is increased, then productivity is improved, but planarity and scratch resistance deteriorate
Solution Approach 1:
The water-soluble polymer intermediary enables high-speed polishing by providing continuous protection to the silicon nitride film during rapid material removal. The polymer's selective adsorption creates a stable protective interface that prevents scratching even under high polishing loads and speeds, allowing productivity improvement without sacrificing planarity or scratch resistance.
Solution Approach 2:
The polishing agent formulation with optimized polymer concentration (0.01-5%), molecular weight (1,000-100,000), and pH (4-9) creates conditions that maintain film protection and grain dispersion at high polishing speeds. These parameter optimizations ensure that even during high-speed polishing, the silicon nitride film remains protected and abrasive grains remain dispersed, maintaining planarity and scratch resistance while achieving high productivity.
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 achieves high selectivity between silicon oxide and silicon nitride films, enabling high-speed polishing with reduced scratches and improved planarity, suitable for advanced semiconductor manufacturing processes.
Implementation Method 1
enhances selectivity by adsorbing onto both the silicon nitride surface and abrasive grains, thereby controlling the polishing rate
Data Source
AI summary
Provided are a polishing agent and a liquid additive for a polishing agent that provide a high selectivity between a silicon oxide film and a silicon nitride film and that inhibit aggregation of abrasive grains, which can cause polishing-induced scratches, as well as a polishing method that enables high-speed polishing and inhibits polishing-induced scratches. A polishing agent includes an abrasive grain, a water-soluble polymer, and water. The water-soluble polymer is a copolymer of a monomer (A) that is at least one selected from an unsaturated dicarboxylic acid, a derivative thereof, and salts thereof, and a monomer (B) other than the monomer (A). The monomer (B) is a monomer that includes an ethylenic double bond and does not include an acidic group. The water-soluble polymer has an acid value of 200 to 450 mgKOH/g.