Data storage devices including a first top electrode and a different second top electrode thereon

A data storage device comprising:

• a transistor on a substrate;
• and
• a data storage structure electrically connected to the transistor,
• wherein the data storage structure comprises:
• a bottom electrode electrically connected to the transistor;
• a magnetic tunnel junction pattern on the bottom electrode;
• and
• a top electrode on the magnetic tunnel junction pattern,
• wherein the top electrode comprises a first top electrode and a second top electrode on the first top electrode,
• wherein the first and second top electrodes comprise a same metal nitride, and
• wherein a density of the first top electrode is higher than a density of the second top electrode.

A data storage device comprising:

• a transistor on a substrate;
• an interconnection structure electrically connected to the transistor;
• a cell contact plug on the interconnection structure;
• a conductive line on the cell contact plug;
• and
• a data storage structure interposed between the cell contact plug and the conductive line,
• wherein the data storage structure comprises:
• a bottom electrode electrically connected to the cell contact plug;
• a top electrode electrically connected to the conductive line;
• a magnetic tunnel junction pattern between the bottom electrode and the top electrode;
• and
• a capping pattern between the magnetic tunnel junction pattern and the top electrode,
• wherein the top electrode comprises a first top electrode, a second top electrode on the first top electrode, and an interface layer between the first and second top electrodes,
• wherein the first and second top electrodes comprise a same metal nitride,
• wherein the first top electrode comprises first crystal grains of the metal nitride and a first void between the first crystal grains,
• wherein the second top electrode comprises second crystal grains of the metal nitride and a second void between the second crystal grains,
• wherein a size of the first void is different from a size of the second void.