Phase change material switch with ovonic threshold switching material selector and methods for forming the same

A method of fabricating a phase change material (PCM) switch, comprising:

• depositing a continuous electrode layer over an upper surface of a lower dielectric material layer;
• depositing a continuous ovonic threshold switching (OTS) layer over an upper surface of the continuous electrode layer;
• etching the continuous OTS layer and the continuous electrode layer through a patterned mask to provide a discrete first electrode over the upper surface of the lower dielectric material layer and a discrete OTS layer over an upper surface of the first electrode;
• forming an upper dielectric material layer over the upper surface of the lower dielectric material layer, over side surfaces of the first electrode, and over side surfaces and an upper surface of the OTS layer;
• performing a planarization process to remove the upper dielectric material layer from over the upper surface of the OTS layer;
• forming a phase change material layer over the upper surface of the OTS layer;
• and
• forming a second electrode and a third electrode contacting the phase change material layer.

A method of fabricating a phase change material (PCM) switch, comprising:

• forming a first electrode;
• forming an ovonic threshold switching (OTS) layer over the first electrode;
• forming a phase change material layer over an upper surface of the OTS layer;
• forming a second electrode and a third electrode contacting the phase change material layer;
• forming a dielectric material layer over the second electrode, the third electrode, and the phase change material layer;
• and
• forming one or more electrical contacts extending through the dielectric material layer and the OTS layer and contacting the first electrode.