Silicon Target for Electron-Beam Memory.
Abstract
A closed-loop beam-positioning scheme was developed for an electron-beam-addressed block-oriented random-access memory (BORAM). Position feedback is achieved by special reference structures, called marker keys, that are built into the storage target. Before each data block is accessed a nearby marker key is scanned with a binary-search position-error-correcting algorithm. This scheme can be applied to any type of storage target by building marker keys into it along with the data storage elements. An experimental memory system was built to exercise the binary search feedback beam positioning scheme. This system consists of a 1-in. -diameter vidicon-like storage tube with electromagnetic deflection and conventional thermionic cathode. The storage target consists of an insulating sapphire substrate on top of which is grown a 1-micrometer conducting layer of N-type silicon. Etched into the silicon layer are marker keys for beam-position feedback, read-only data elements of different sizes to test the resolution of the beam positioning, and a variety of experimental data storage structures. At a beam current of 130 nA the beam is approximately Gaussian with a standard deviation of 0.5 mil. The feedback beam positioning method is capable of resolving read-only data bits spaced on 1.2-mil centers, which is close to the beam diameter. Access time is 130 microseconds. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1973
- Accession Number
- AD0912925
Entities
People
- Frank J. Marlowe
Organizations
- Sarnoff Corporation