Method of forming memory device having capacitor including layer of high dielectric constant

A method of forming a memory device having a capacitor including a high dielectric constant layer, comprising:

• forming a groove for an alignment key concurrently with a contact hole on a substrate;
• forming a conductive layer to fill the contact hole and cover the inner surface of the groove;
• conformally stacking a capping layer as an oxygen barrier on the conductive layer;
• planarizing the capping layer and the conductive layer by chemical mechanical polishing to leave the conductive layer and the capping layer only covering the inner surface of the groove and on a bottom and inner sidewalls of the contact hole, thereby forming a contact plug filling the contact hole;
• stacking a capacitor bottom electrode layer to contact the top surface of the contact plug;
• stacking a high dielectric constant layer on the bottom electrode layer;
• and performing an oxidation treatment at a high temperature to crystallize the high dielectric constant layer.