Browse Prior Art Database

Method for Improved Process Control of Lubricant Layer Thickness on Thin Film Disks

IP.com Disclosure Number: IPCOM000109948D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 55K

Publishing Venue

IBM

Related People

Leung, WC: AUTHOR [+4]

Abstract

Thin film disks are coated with a thin layer of organic lubricant whose thickness has to be kept in a small operating window to provide satisfactory durability and stiction performance. Current techniques for monitoring this thickness are very time consuming, so that only a few points can be sampled on a disk. This technique provides a rapid method for process control of lubricant uniformity over the entire disk. We disclose here a simple optical interference technique for measuring lube thickness which permits measurements at a rate limited only by mechanical scanning limits. Thus entire disk surfaces can be mapped in approximately 1 minute. The typical disk structure consists of a substrate, a magnetic thin film which is highly reflective, a protective dielectric overcoat, and a thin lubricant layer.

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Method for Improved Process Control of Lubricant Layer Thickness on Thin Film Disks

      Thin film disks are coated with a thin layer of organic
lubricant whose thickness has to be kept in a small operating window
to provide satisfactory durability and stiction performance.  Current
techniques for monitoring this thickness are very time consuming, so
that only a few points can be sampled on a disk.  This technique
provides a rapid method for process control of lubricant uniformity
over the entire disk.  We disclose here a simple optical interference
technique for measuring lube thickness which permits measurements at
a rate limited only by mechanical scanning limits.  Thus entire disk
surfaces can be mapped in approximately 1 minute.  The typical disk
structure consists of a substrate, a magnetic thin film which is
highly reflective, a protective dielectric overcoat, and a thin
lubricant layer.  When a collimated light beam is incident on the
disk, beams are reflected at the lubricant surface, the dielectric
overcoat surface, and the magnetic coating surface.  These reflected
beams all interfere and the resultant intensity is determined by the
wavelength of light, the thicknesses of the lube and overcoat layers,
the optical constants of the layers, and the angle of incidence.  By
carefully measuring the reflectivity of the disk with and without
lubricant, using an integrating sphere apparatus and looking at the
difference of the two reflectivities, it is possib...