Browse Prior Art Database

Non-Magnetic Write/Read Storage Device

IP.com Disclosure Number: IPCOM000115512D
Original Publication Date: 1995-May-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+2]

Abstract

Disclosed is a non-magnet write/read data storage device that utilizes a "shape memory" alloy, and Diamond Like Carbon films (DLC). The disclosed device has the advantage of being independent of the spin orientations, curie temperatures, coercivity, sharpness, which are difficult to control during thin film processing. In addition, the Signal to Noise Ratio (SNR) of magneto-optic storage materials is relatively low, the head is complex, requiring a polarizer and analyzer and a quarter wave plate.

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Non-Magnetic Write/Read Storage Device

      Disclosed is a non-magnet write/read data storage device that
utilizes a "shape memory" alloy, and Diamond Like Carbon films (DLC).
The disclosed device has the advantage of being independent of the
spin orientations, curie temperatures, coercivity, sharpness, which
are difficult to control during thin film processing.  In addition,
the Signal to Noise Ratio (SNR) of magneto-optic storage materials is
relatively low, the head is complex, requiring a polarizer and
analyzer and a quarter wave plate.

      The Shape Memory Alloy (SMA), Nickel-Titanium, which is one
example of a family of shape memory alloys that have been developed
(1) has a unique property of assuming its original shape when heated
to a critical temperature, Tcrit, once its memory has been preset.
The principle behind the shape memory effect is the temperature
dependent changes in the materials crystal structure, e.g., heat
transforms the alloy to its high temperature phase where the memory
has been set.

      A transparent substrate such as glass, silica, sapphire etc. is
blanket coated with an adhesion layer such as titanium.  A
photoresist layer is then spin coated, exposed and developed forming
a delineated pattern.  The adhesion layer exposed in the resist
stencil is then etched, as is a portion of the transparent substrate
by either wet or dry processing.  A layer of amorphous silicon, 2 to
4 nm thick is then blanket deposited, followed by a layer of DLC
utilizing a Plasma Assisted Chemical Vapor Deposition (PACVD) process
(2).  The amorphous silicon film provides interfacial adhesion of the
DLC to the etched transparent substrate (3).  A low temperature wax
is deposited, again a blanket coating.  The choice of wax is a
function of its molecular weight (M.W.) which controls the
vaporization as well as the condensation temperature.  The resist
stencil and the overcoated layers are then stripped by solvents and
ultrasonics.  The shape memory alloy (SMA) Nickel-Titanium is then
deposited over the structure.

      Setting of the memory is done by heating the stor...