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ACIDIC/ALKALINE DIAMOND SLURRY FOR USE IN CHEMCIAL / MECHANICAL PLANARIZATION OF SEMI-CONDUCTOR WAFERS

IP.com Disclosure Number: IPCOM000010026D
Publication Date: 2002-Oct-09
Document File: 3 page(s) / 74K

Publishing Venue

The IP.com Prior Art Database

Abstract

A stable, well-dispersed suspension formulation comprising diamond micron powder with a specially formulated mixture of water and organic compounds for use in lapping applications for semiconductor wafers / the chemical mechanical planarization of semiconductor circuits, for superior removal rates and surface finishes relative to the currently available silicon and alumina slurries.

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ACIDIC/ALKALINE DIAMOND SLURRY FOR USE IN CHEMCIAL / MECHANICAL PLANARIZATION OF SEMI-CONDUCTOR WAFERS

 

BACKGROUND

                    Current CMP technology utilizes silica and alumina based slurries in high solids concentrations.  Diamond particles are much harder than those used in existing slurries.  Because of the increased hardness, the corresponding slurries will result in improved material removal rates and surface finishes of the semi-conductor wafer.

                    There is a need for new slurries comprising diamond micron powder, organic additives, and water to be used in the chemical / mechanical planarization of integrated circuit wafers.  

                    We have found that the use of diamond micron powder in the slurry provides superior removal rates and surface finishes relative to the currently available silicon and alumina slurries.  Typically, diamond suspension under acidic conditions is not stable.  The organic additives stabilize the diamond dispersion and prevent the formation of diamond aggregates which cause scratches in the IC / semiconductor wafer.  This helps improve process cycle times and surface finish of semi-conductor wafers.

                     

DETAILED DESCRIPTION

                       

                    In this paper, we will describe the process wherein diamond powder is combined with a specially formulated mixture of water and organic compounds to produce a stable, well-dispersed suspension.  When used in lapping applications for semiconductor wafers, this formulation will result in superior lapping rates and surface finishes.

                    The new slurry formulations contain diamond micron powder, two non-ionic surfactants (one water soluble component, preferable polyethylene oxide sorbitan monolaurate and one oil soluble component, preferable sorbitan monooleate), and one polyglycol (preferably low molecular weight polypropylene glycol).  The formulation also includes a polymeric component (preferably ethylene oxide propylene oxide block copolymer) for better control of wettability.  The pH is adjusted with small amounts of acetic acid.  The invention produces a dispersible diamond slurry formulation with improved stability against aggregation and separation and ease of dispersibility.  It further increases stability against aggregation during storage after dilution with water.   

                    The diamond powder used is less than 5 microns in size with a mean size less than 1 micron.  The weight percent of diamond in the dilute slurry is between 0.1% and 5%.  The pH of the dilute slurry is between 8 and 12.

                    EXPERIMENTS.   In the following experiment, the preparation of the slurry involved four main steps:

a)                 preparation of the surfactant composition

b)                 dispersion of the diamond particles in the liquid

c)                  dilution of the concentrated suspens...