The instant disclosure relates to a high-k metal gate random access memory. The memory includes a substrate, a plurality of bit line units, source regions, gate structures, drain regions, word line units, and capacitance units. The substrate has a plurality of trenches, and the bit line units are arranged on the substrate. The source regions are disposed on the bit line units, and the gate structures are disposed on the source regions. Each gate structure has a metal gate and a channel area formed therein. The gate structures are topped with the drain regions. The word lines units are arranged between the source and drain regions. The capacitance units are disposed on the drain regions. Another memory is also disclosed, where each drain region and a portion of each gate structure are disposed in the respective capacitance unit, with the drain region being a lower electrode layer.