Microelectronic devices using sacrificial layers and structures fabricated by same

A semiconductor memory device, comprising:

• a microelectronic substrate including a first conductive region;
• a silicon nitride layer and/or a silicon oxynitride layer on the first conductive region;
• a contact plug extending from a surface of the silicon nitride layer and/or a silicon oxynitride layer through an opening therein to the first conductive region;
• a phase changeable material region on the contact plug and the silicon nitride layer and/or a silicon oxynitride layer;
• and
• a second conductive region on the phase changeable material region.

A semiconductor memory device including a phase changeable material, comprising:

• a semiconductor substrate;
• an interlayer dielectric layer formed on the substrate;
• a first conductive region formed in the interlayer dielectric layer;
• a silicon nitride layer and/or a silicon oxynitride layer on the first conductive region and the interlayer dielectric layer;
• a contact plug extending from a surface of the silicon nitride layer and/or silicon oxynitride layer through an opening therein to a portion of the first conductive region;
• a phase changeable material region on the contact plug and the silicon nitride layer and/or silicon oxynitride layer;
• and
• a second conductive region on the phase changeable material region.