The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 13, 2005
Filed:
Nov. 26, 2002
Chitra K. Subramanian, Austin, TX (US);
Joseph J. Nahas, Austin, TX (US);
Chitra K. Subramanian, Austin, TX (US);
Joseph J. Nahas, Austin, TX (US);
Freescale Semiconductor, Inc., Austin, TX (US);
Abstract
In a magnetoresistive random access memory (MRAM), a magnetic tunnel junction (MTJ) () cell is stacked with an asymmetric tunnel device (). This device, when used in a crosspoint MRAM array, improves the sensing of the state or resistance of the MTJ cells. Each MTJ cell has at least two ferromagnetic layers () separated by an insulator (). The asymmetric tunnel device () is electrically connected in series with the MTJ cell and is formed by at least two conductive layers () separated by an insulator (). The asymmetric tunnel device may be a MIM (), MIMIM () or a MIIM (). Asymmetry results from conducting electrons in a forward biased direction at a significantly greater rate than in a reversed biased direction. Materials chosen for the asymmetric tunnel device are selected to obtain an appropriate electron tunneling barrier shape to obtain the desired rectifying current/voltage characteristic.