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Personalization of ROS Memories Using an E Beam System

IP.com Disclosure Number: IPCOM000088642D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Moore, RD: AUTHOR [+2]

Abstract

A technique is described for use of an electron (E)- beam system for efficient personalization of read-only store (ROS) memories. The E-beam system is used in conjunction with a processing technique to modify the electrical connections in an array of a ROS memory chip.

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Personalization of ROS Memories Using an E Beam System

A technique is described for use of an electron (E)- beam system for efficient personalization of read-only store (ROS) memories. The E-beam system is used in conjunction with a processing technique to modify the electrical connections in an array of a ROS memory chip.

A typical ROS memory is made up of a 2 dimensional array of diodes. The presence of a diode represents a logical "1"; the absence a "0". The technique proposed is that all diodes be formed in the normal ROS manufacturing process with the diodes either all connected or all unconnected. Then at the last, or a very late, processing step, personalize the ROS by either deleting or inserting connections by means of programmed E-beam exposure.

A very fast personalizing exposure can be achieved by establishing a novel sequence of deflection control commands which cause the magnetically deflectal beam to step to and pause at each potential exposure area, rather than rastering over the entire exposure field. At each such potential exposure site a small electrostatic raster is superimposed on the deflection, covering the area which may or may not require exposure. Thus, the electromagnetic and electrostatic components of the writing cycle are tailored to each ROS family or masterslice. The actual personality of the ROS is controlled by the exposure pattern, i.e., whether or not the beam is unblanked while it is being rastered over each potential exposure area. The exposure pattern can be derived in a straightforward fashion from the desired ROS personality, expressed as a set of binary digits.

A disadvantage of this approach is that it demands highly accura...