Methods of forming metal contact structures and methods of fabricating phase-change memory devices using the same

A method of fabricating a phase-change memory comprising:

• forming a first interlayer insulating layer on a substrate having a contact plug;
• etching the first interlayer insulating layer to form a contact hole that exposes the contact plug;
• depositing a metal layer on the surface of the first interlayer insulating layer including inside of the contact hole;
• planarizing the metal layer to provide a buried portion of the metal layer in the contact hole and to remove portions of the metal layer outside of the contact hole;
• etching-back the buried portion of the metal layer in the hole such that some of the buried portion of the metal layer within the hole remains;
• depositing a conductive layer on the surface of the first interlayer insulating layer and the metal layer that remains within the hole to substantially fill the hole;
• planarizing the conductive layer to remove portions of the conductive layer formed on an upper surface of the first interlayer insulating layer to provide a contact pad comprising the metal layer that remains within the hole and the conductive layer in the contact hole;
• forming a second interlayer insulating layer on the first interlayer insulating layer including the contact pad;
• forming a lower electrode contact in the second interlayer insulating layer and in contact with an upper surface of the contact pad;
• and
• sequentially forming a phase-change layer, an upper electrode layer and an upper electrode contact layer on the lower electrode contact.