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SANDWICH STRUCTURE TO IMPROVE AND PROTECT OPTICAL DISK MEDIA

IP.com Disclosure Number: IPCOM000025477D
Original Publication Date: 1985-Aug-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 84K

Publishing Venue

Xerox Disclosure Journal

Abstract

The optical disk sandwich structure described herein is a substitute for the Phillips trilayer disk. It is designed for the optical disk requirements of a read only player. The figure shows tellurium (Te) as the recording medium which requires protection from humidity and corrosive furnes. Disk edges are masked off during the Te and MgF2depositions. The MgF2 is the transparent spacer layer 1/4 wavelength in thickness. MgF2 is a low refractive index (1.38) coating that is substituted for Si02 in antireflection and bandpass filter coatings. A passivation agent is required to protect the MgF2 as well as the Te.

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KEROX DISCLOSURE JOURNAL

SANDWICH STRUCTURE TO IMPROVE AND PROTECT OPTICAL DISK MEDIA U.S. C1. 365/126 Roberta M. Fay

Proposed C 1 assif ication

Int. C1. Gllc 11/46

BACKER PLATE

                         /ADHESIVE F T a

  (50-70A) Au (300A)

NOTE: .

NOT DRAWN TO SCALE. FULL DISK NOT SHOWN. BACKER PLATE MAY BE BONDED TO ANOTHER DATA DISK ON OTHER SIDE.

The optical disk sandwich structure described herein is a substitute for the Phillips trilayer disk. It is designed for the optical disk requirements of a read only player.

The figure shows tellurium (Te) as the recording medium which requires protection from humidity and corrosive furnes. Disk edges are masked off during the Te and MgF2depositions. The MgF2 is the transparent spacer layer 1/4 wavelength in thickness. MgF2 is a low refractive index (1.38) coating that is substituted for Si02 in antireflection and bandpass filter coatings. A passivation agent is required to protect the MgF2 as well as the Te.

The chromium (Cr) provides nucleation sites for the gold (Au) atoms,to latch on to and build a stable three dimensional structure. A 10 - 30A Cr flash substantially improves gold (Au) adhesion to the underlying materials. Disk edges are not masked off during this or subsequent depositions.

The Au is the reflector layer substituting for aluminum (All and the passivation agent for the Te and MgF2. The Au coating is generally soft and malleable, hence not likely to develop mechanical and thermal stresses.

The tantalum (Ta) segregates very strongly at the grain boundaries of the Au. Thus, any grain boundaries or defects where moisture can...