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Dual Pass Sputtering to Eliminate In Line Anisotropy Effects

IP.com Disclosure Number: IPCOM000121820D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 53K

Publishing Venue

IBM

Related People

Hagan, JA: AUTHOR [+5]

Abstract

Thin-film disks made using in-line sputtering systems are observed to have magnetic properties that coincide with the sputtering direction. On very smooth substrates, macromagnetic properties, such as coercivity (Hc) and MrT (remanence-thickness product), modulate because of the circular disk geometry having a uniaxial anisotropy. The use of circumferential texturing methods has eliminated the variation in macromagnetic properties. However, recently, more subtle remnants of the in-line anisotropy have been detected. A bit shift has been observed on thin-film disks that varies as the disk rotates through the weak in-line anisotropy. This varying bit shift with angle of rotation aggravates the electronic channel detection scheme for the recorded bits.

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Dual Pass Sputtering to Eliminate In Line Anisotropy Effects

      Thin-film disks made using in-line sputtering systems are
observed to have magnetic properties that coincide with the
sputtering direction.  On very smooth substrates, macromagnetic
properties, such as coercivity (Hc) and MrT (remanence-thickness
product), modulate because of the circular disk geometry having a
uniaxial anisotropy.  The use of circumferential texturing methods
has eliminated the variation in macromagnetic properties.  However,
recently, more subtle remnants of the in-line anisotropy have been
detected.  A bit shift has been observed on thin-film disks that
varies as the disk rotates through the weak in-line anisotropy.  This
varying bit shift with angle of rotation aggravates the electronic
channel detection scheme for the recorded bits.  Degradation in the
detection scheme is manifested by error clustering on the top or
bottom half of disk depending on the sputter direction.  An in-line
sputtering technique which tends to normalize this anisotropy and
consequently randomize the errors is described.

      A solution to this problem is to normalize the in-line
anisotropy by sputtering the disk in a multipass operation where the
disk is moved past the sputtering target twice, the first pass being
in one direction, and the second pass being in the reverse direction.
The sputtering parameters are adjusted to give the total thickness
desired.  The multipass operation creates a fi...