CMP Slurry Polishing with Opposite Zeta Potential Abrasives
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Solution Overview
Problem
The chemical mechanical polishing (CMP) process in semiconductor manufacturing often results in defects such as scratches due to electrostatic agglomeration of abrasives with opposite zeta potentials, which existing methods fail to effectively mitigate.
Innovation Solution
A method involving the use of two slurries with abrasives of opposite zeta potentials, followed by a rinsing process with a chemical solution of opposite polarity to remove the first abrasive, preventing electrostatic agglomeration and reducing defects during CMP processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single slurry with one type of abrasive is used for CMP, then the polishing process is simple, but defects such as scratches occur due to electrostatic agglomeration of abrasives
Solution Approach 1:
The polishing process is segmented into two sequential steps: first polishing with a slurry containing abrasives of a first polarity, then rinsing with a solution of second polarity to remove those abrasives, and finally polishing with a slurry containing abrasives of second polarity. This segmentation prevents electrostatic agglomeration by ensuring that only one type of abrasive is present on the substrate at any given time, thereby reducing defects while maintaining process control.
Solution Approach 2:
A rinsing solution with chemical properties of second polarity is introduced as an intermediary between the two polishing steps. This intermediary solution removes the first polarity abrasives from the substrate surface through electrostatic repulsion and chemical interaction, preventing their agglomeration with second polarity abrasives in the subsequent polishing step.
2Manufacturing precision
If abrasives with opposite zeta potentials are used to improve polishing performance, then polishing effectiveness increases, but electrostatic agglomeration occurs causing scratches and defects
Solution Approach 1:
The rinsing step with second polarity solution is performed as a preliminary action before introducing the second polarity abrasives. This preliminary rinsing removes all first polarity abrasives from the substrate surface, creating a clean state that prevents electrostatic agglomeration when the second polarity abrasives are subsequently applied.
Solution Approach 2:
The electrostatic properties of the abrasives, which cause harmful agglomeration when both types are present simultaneously, are converted into a beneficial separation mechanism. By using rinsing solutions with opposite polarity to the incoming abrasive, the electrostatic repulsion effectively removes unwanted abrasives from the surface, turning the electrostatic force from a harmful to a useful effect.
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
This approach significantly reduces the number of defects on the semiconductor surface by inhibiting the formation of large particles and minimizing excessive polishing, thereby improving the planarization and quality of the semiconductor device.
Implementation Method 1
a first abrasive having a zeta potential of a first polarity
Implementation Method 2
rinsing a surface of the object layer, using a rinsing solution including a chemical of a second polarity, opposite to the first polarity
Implementation Method 3
a second abrasive having a zeta potential of a second polarity, opposite to the first polarity
Data Source
AI summary
A method of manufacturing a semiconductor device includes preparing an object layer on a substrate; polishing the object layer with a first slurry including a first abrasive having a zeta potential of a first polarity; rinsing a surface of the object layer, using a rinsing solution including a chemical of a second polarity, opposite to the first polarity; and polishing the object layer with a second slurry including a second abrasive having a zeta potential of a second polarity, opposite to the first polarity.