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Method for on-tool CMP absolute particle filtration

IP.com Disclosure Number: IPCOM000042244D
Publication Date: 2005-Feb-03
Document File: 2 page(s) / 86K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for on-tool chemical mechanical planarization (CMP) absolute particle filtration. Benefits include improved performance and improved process simplicity.

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Method for on-tool CMP absolute particle filtration

Disclosed is a method for on-tool chemical mechanical planarization (CMP) absolute particle filtration. Benefits include improved performance and improved process simplicity.

Background

              Oversize particles (OSPs) can cause scratching in silicon wafers, which makes the wafers unusable.

      Conventional slurries have OSPs that are either large particles or agglomerates of small particles. The OSP problem is solved by using depth filters that can pass large particles. Additionally, slurry streams are monitored to ensure integrity.

Description

      The disclosed method is a non-membrane method of absolute filtration. The slurry is filtered just prior to being dispensed into the CMP tool.

      The disclosed method is similar to the way a burr grinder is used to control coffee particle size. A burr CMP filter (BCMP) passes small particles, shears apart agglomerations, and excludes large particles.

      The disclosed method takes advantage of the boundary layer that exists in flowing liquids at interfaces. For example, a ball in a cavity spins at an offset angle creating a free-flow region (see Figure 1).

              A small particle moves through free-flow region between boundary layers. Large particles are excluded. The cavity and ball can be made of materials that are attracted to magnets so that down-field magnets remove impurities. Any agglomerations larger than the free flow region are under...