Patent ID: 9053785
Filing Date: 2015-06-09
Classification: G11C,H01L

Abstract:
1. A phase-change memory cell, comprising: a phase change material; a reference electrical terminal disposed on first side of the phase change material; first and second electrical terminals disposed on a second side of the phase change material, the first and second electrical terminals being separated by an insulator disposed therebetween; the phase-change material configured to be reversibly transformable between an amorphous phase and a crystalline phase, in response to a phase-altering electrical signal applied to the phase-change material via the reference electrical terminal and one or more of the first and second electrical terminals; a resistance measurement unit configured to measure a respective electrical resistance between each of the first and electrical terminals and the reference electrical terminal; and a mathematical operation unit configured to determine a mathematical relation between the respective electrical resistances measured between each of the electrical terminals and the reference electrical terminal; wherein a characteristic of the respective electrical signals supplied to the electrical terminals is selected so that an amorphous area of a desired size and spatial distribution is formed in the phase-change material such that the spatial distribution of the amorphous area is independently variable in size along a first direction defined between the reference electrical terminal and the first electrical terminal, and variable in size along a second direction defined between the reference electrical terminal and the second electrical terminal, so as to provide at least 7 different discernable resistance levels.