Browse Prior Art Database

Read Only Store

IP.com Disclosure Number: IPCOM000073574D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Fischler, AS: AUTHOR [+2]

Abstract

Described is a high density Read Only Store (ROS) device which can be addressed and read by a light beam, laser beam, electron beam, or a combination of these and with a storage capacity in excess of 10/8/ bits/in/2/. The device consists of a silicon substrate 1 as shown in A with a shallow junction or Schottky barrier 2 on one surface and an ohmic region 3 on the other surface. The junction or barrier is found by a metallic layer 4.

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Read Only Store

Described is a high density Read Only Store (ROS) device which can be addressed and read by a light beam, laser beam, electron beam, or a combination of these and with a storage capacity in excess of 10/8/ bits/in/2/. The device consists of a silicon substrate 1 as shown in A with a shallow junction or Schottky barrier 2 on one surface and an ohmic region 3 on the other surface. The junction or barrier is found by a metallic layer 4.

The silicon consists of a layer of low resistivity silicon on which an epitaxial layer of the same type has been grown. This reduces the resistance of the device and gives rise to a depletion region width somewhat the same as achieved by a device made of high resistivity material.

The depletion layer is thick enough to absorb the radiation from the light or all the electrons from the e-beam at the operating level for read.

To store information in the device, the beam or laser is used to form a small hole in the metal during this operation. The device is reverse biased and a signal level of the appropriate magnitude determines when the hole is achieved. A series of holes or lack of holes is used to represent stored bits. This information is read by scanning the device, just as in the write operation but at a much faster rate. After writing, a thin film of 100-200 angstroms of Al can be used as an overcoating to avoid charge buildup or noise due to line of sight exposure to filaments or beams. The device shown in B thus...