Browse Prior Art Database

Reclaiming Magnetic Bubble Memory Chips

IP.com Disclosure Number: IPCOM000078913D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Horstmann, RE: AUTHOR [+2]

Abstract

Magnetic bubble domain memory chips consist of a highly polished, non-magnetic garnet substrate upon which is deposited an epitaxial layer of magnetic garnet. The epitaxial layer is then coated with a layer of amorphous SiO(2), which serves as both a spacer between the magnetic layer and the overlay, and as a substrate for the overlay. A thin layer of magnetoresistive (MR) material (e.g., permalloy) is evaporated on the SiO(2). A permalloy propagation pattern is then deposited on the MR layer. The excess MR layer is then etched away and the entire crystal coated with a protective coating of photoresist, leaving the finished chip as pictured in Fig. 1.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 68% of the total text.

Page 1 of 2

Reclaiming Magnetic Bubble Memory Chips

Magnetic bubble domain memory chips consist of a highly polished, non- magnetic garnet substrate upon which is deposited an epitaxial layer of magnetic garnet. The epitaxial layer is then coated with a layer of amorphous SiO(2), which serves as both a spacer between the magnetic layer and the overlay, and as a substrate for the overlay. A thin layer of magnetoresistive (MR) material (e.g., permalloy) is evaporated on the SiO(2). A permalloy propagation pattern is then deposited on the MR layer. The excess MR layer is then etched away and the entire crystal coated with a protective coating of photoresist, leaving the finished chip as pictured in Fig. 1.

By far the most expensive and difficult step in the fabrication of this device is the deposition of the epitaxial layer. It is, therefore, extremely undesirable to have to discard the entire chip because of a fault in subsequent fabrication steps, or due to an error in the design of the propagation pattern.

A process for reclaiming the chips after they have been made useless by fabrication faults or design errors is provided as set forth below:

1) The chip is first thoroughly rinsed in acetone to remove all traces of photoresist and grease.

2) The clean chip is then imnersed in 32 degrees Baume ferric chloride solution for 30 seconds, then rinsed in demineralized water, acetone and ethanol, in that order, and blown dry. The chip is now clean except for an etched pattern in th...