Polishing Composition Reduces Level Differences in Semiconductor Patterns
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Solution Overview
Problem
Conventional polishing compositions fail to effectively minimize level differences between dissimilar materials and between coarse and dense portions of patterns during the semiconductor manufacturing process, leading to excessive scraping of materials like polycrystalline silicon, silicon oxide, and silicon nitride, especially at fine pattern formations.
Innovation Solution
A polishing composition containing a level difference modifier with a specific structure, featuring an aromatic ring and a sulfo group or its salt, combined with abrasive grains of 5 to 50 nm average primary particle size, is used to reduce unintentional level differences. This composition includes compounds represented by specific chemical formulas and their salts, polymers, and copolymers, along with a dispersing medium with a pH less than 7.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional polishing composition is used, then polishing speed on soft materials like polycrystalline silicon and silicon oxide is improved, but excessive scraping occurs leading to dishing phenomenon and level differences
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing slurry by incorporating specific organic acids (oxalic acid, malonic acid, succinic acid, or glutaric acid) at controlled concentrations (0.01-10 wt%). This chemical parameter modification alters the reaction kinetics between the polishing slurry and different wafer materials, enabling selective polishing that maintains high speed on convex portions while protecting concave portions from excessive scraping, thus resolving the contradiction between polishing speed and flatness.
2Productivity
If polishing composition reacts strongly with soft materials, then material removal speed increases, but level differences between dissimilar materials increase
Solution Approach 1:
The patent applies local quality by creating spatially differentiated polishing effects across the wafer surface. The organic acid-based polishing slurry selectively reacts with exposed convex portions of soft materials (polycrystalline silicon, silicon oxide) while the viscous slurry formulation allows it to flow into and protect concave portions. This local differentiation enables high material removal speed on convex areas while maintaining minimal scraping in concave areas, thereby achieving both high productivity and minimal level differences.
3Reliability
If conventional polishing slurry is used, then general polishing performance is maintained, but fine pattern portions are excessively scraped
Solution Approach 1:
The patent employs a composite polishing slurry formulation combining organic acids (oxalic, malonic, succinic, or glutaric acid) with specific viscosity characteristics and controlled pH levels. This composite material approach creates a slurry with differentiated chemical reactivity and rheological properties that enable it to selectively polish convex portions while the viscous nature allows the slurry to remain in concave portions with fine patterns, providing protective cushioning. This resolves the contradiction by maintaining reliable polishing performance while preventing excessive scraping of fine pattern portions.
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 solution effectively decreases level differences between dissimilar materials and between coarse and dense pattern portions, resulting in a flatter patterned wafer surface by protecting the wafer surface from mechanical action and optimizing polishing speeds.
Implementation Method 1
CMP (Chemical Mechanical Polishing) has become an essential process
Implementation Method 2
it is thus difficult to form a perfect flat surface
Implementation Method 3
the actions of polishing composition on the respective materials are different from one another
Implementation Method 4
CMP (Chemical Mechanical Polishing) has become an essential process
Data Source
AI summary
The present invention provides a polishing composition with which it is possible to decrease a level difference to be unintentionally generated between dissimilar materials and a level difference to be unintentionally generated between coarse and dense portions of a pattern. The present invention relates to a polishing composition which contains abrasive grains having an average primary particle size of 5 to 50 nm, a level difference modifier containing a compound with a specific structure, having an aromatic ring and a sulfo group or a salt group thereof which is directly bonded to this aromatic ring, and a dispersing medium and of which the pH is less than 7.