CMP Filter Flow Control for Particle Scratches
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Solution Overview
Problem
In chemical mechanical polishing (CMP) processes, coarse particles in the polishing slurry can agglomerate and be discharged onto the substrate, causing scratches due to pressure differences across filters, which existing systems fail to prevent effectively.
Innovation Solution
Implementing a polishing method and apparatus that regulates the flow rate or pressure of the polishing liquid through a filter until a predetermined set value is reached, and optionally performing intermittent or high-flow-rate filter cleaning processes to prevent coarse particle discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the polishing liquid is supplied at high flow rate to improve polishing efficiency, then the productivity increases, but the pressure difference across the filter increases causing coarse particles to be discharged onto the polishing pad
Solution Approach 1:
The filter is cleaned in advance by supplying polishing liquid at high flow rate before the normal polishing operation. This preliminary high-flow-rate flushing removes accumulated coarse particles from the filter, preventing them from being discharged during subsequent normal-flow-rate polishing operations.
Solution Approach 2:
The system periodically switches between high-flow-rate mode (for filter cleaning) and normal-flow-rate mode (for polishing). This periodic alternation allows the filter to be cleaned at intervals during operation, maintaining effective filtration while enabling continuous polishing production.
2Manufacturing precision
If the filter is cleaned frequently to prevent coarse particle discharge, then the manufacturing precision improves, but the loss of time increases due to frequent cleaning interruptions
Solution Approach 1:
The filter is cleaned in advance before polishing operations begin, ensuring that coarse particles are removed prior to any potential damage. This preliminary cleaning action prevents the need for frequent interruptions during polishing, as the filter remains effective throughout the operation.
Solution Approach 2:
The filter cleaning is performed during idle periods or before polishing starts, allowing the polishing operation to continue continuously without interruptions. The useful polishing action remains uninterrupted while the filter maintenance is scheduled during non-productive time windows.
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
Prevents coarse particle discharge onto the substrate, thereby minimizing surface scratches and ensuring a smooth, mirror-like finish during CMP processes.
Implementation Method 1
a filter (104) for catching the coarse particles
Implementation Method 2
The most important one of the planarizing technologies is chemical mechanical polishing (or CMP)... a polishing liquid, containing abrasive particles such as silica (SiO2) or ceria (CeO2)
Data Source
AI summary
A polishing method of polishing a substrate while preventing coarse particles from being discharged onto a polishing pad is disclosed. In this polishing method, a substrate is brought into sliding contact with a polishing pad while a polishing liquid, which has passed through a filter, is supplied onto the polishing pad. The polishing method includes: passing the polishing liquid through the filter while increasing a physical quantity of the polishing liquid until the physical quantity reaches a predetermined set value, the physical quantity being one of flow rate and pressure of the polishing liquid; and polishing the substrate W on the polishing pad while supplying the polishing liquid that has passed through the filter onto the polishing pad.