Phase change memory device in which a distance between a lower electrode and a ground line is increased to secure the sensing margin of a cell and method for manufacturing the same

A method for manufacturing a phase change memory device, comprising the steps of:

• preparing a semiconductor substrate which has a plurality of bar type active regions and an isolation structure separating the active regions;
• forming a plurality of gate lines on the semiconductor substrate to extend in a direction perpendicular to the active regions;
• forming a plurality of source regions, each source region being on a first side of each gate line;
• forming a plurality of drain regions, each drain region being on a second side of the gate line, the second side being opposite the first side.
• forming a dot type lower electrode including a first contact plug in the drain region of the substrate and forming second contact plugs in the source region and the isolation structure in the shape of a line parallel to the gate lines;
• forming a lower electrode contact on the lower electrode;
• forming a phase change layer and an upper electrode on the lower electrode contact;
• forming an upper electrode contact on the upper electrode;
• forming a plurality of contacts for ground lines between the active regions to come into contact with the second contact plugs;
• and
• forming a bit line in each active region to be connected with the upper electrode contact and forming ground lines between the active regions to be connected with the contacts for ground lines.