Methods of forming multi-level cell of semiconductor memory

Abstract

Provided is a method of forming a semiconductor memory cell in which in order to store two bits or more data in a memory cell, three or more bottom electrode contacts (BECs) and phase-change materials (GST) have a parallel structure on a single contact plug (CP) and set resistances are changed depending on thicknesses (S), lengths (L) or resistivities (ρ) of the three or more bottom electrode contacts, so that a reset resistance and three different set resistances enable data other than in set and reset states to be stored. Also, a method of forming a memory cell in which three or more phase-change materials (GST) have a parallel structure on a single bottom electrode contact, and the phase-change materials have different set resistances depending on composition ratio or type, so that four or more different resistances can be implemented is provided.