Phase Change Memory with Various Grain Sizes

A method of forming a memory device comprising:

• forming a cup shaped heater element, the cup having a ring shaped top surface;
• forming a fine grain phase change layer in contact with a portion of the ring shaped top surface;
• and
• forming a coarse grain phase change layer on the fine grain phase change layer.

A method of forming a memory device comprising:

• forming over a substrate a heater element;
• depositing on at least a portion of the heater element a fine grain phase change layer;
• depositing on the fine grain phase change layer a coarse grain phase change layer;
• and
• forming an electrical contact to the coarse phase change layer or the heater element or both.

A method of forming a memory device comprising:

• forming a transistor on a substrate;
• forming a conductive feature in a first dielectric layer above the substrate;
• forming a crown oxide on the first dielectric layer and conductive feature;
• patterning the crown dielectric to form a trench therein, the trench exposing the conductive feature;
• conformally forming a heater element layer over the crown dielectric and in the trench, wherein the heater element layer electrically contacts the conductive feature and defines a ring structure having a hollow defined therein;
• filling the hollow by forming a second dielectric layer in the hollow and over the heater element layer;
• planarizing the second dielectric and the heater element layer to a top surface of the crown oxide, forming a heater element having a ring structure in a plane parallel to a major surface of the substrate and a remaining crown dielectric portion within the ring structure;
• depositing a third dielectric over heater element and the remaining crown dielectric portion and forming a trench in the third dielectric, wherein the trench exposes at least one sidewall of the ring structure;
• depositing a fine grain phase change layer in the trench, wherein the fine grain phase change layer electrically contacts the at least one sidewall of the ring structure;
• depositing a coarse grain phase change layer on the fine grain phase change layer;
• and
• forming an electrical contact on the coarse grain phase change layer.