Memory device with improved data retention

A multiple-time programmable (MTP) memory device, comprising:

• a substrate;
• a source region formed in the substrate, wherein the source region comprises a top surface;
• a gate dielectric formed on the substrate;
• a gate structure formed on the gate dielectric, wherein the gate structure comprises a sidewall;
• a first spacer formed on the sidewall of the gate structure and the top surface of the source region;
• a second spacer formed on a sidewall of the first spacer;
• a third spacer formed on the first spacer and in contact with the second spacer;
• and
• a fourth spacer formed on the third spacer.

A method for forming a memory device, comprising:

• providing a substrate, wherein the substrate comprises source and drain regions in the substrate;
• forming a gate dielectric on the substrate;
• forming a gate structure on the gate dielectric, wherein the gate structure comprises a sidewall;
• depositing a first sub-spacer layer;
• forming a second sub-spacer on the first sub-spacer layer;
• depositing a third sub-spacer layer;
• forming a fourth sub-spacer on the third sub-spacer layer;
• etching the third sub-spacer layer to form a third sub-spacer on the first sub-spacer layer and the second sub-spacer;
• and
• etching the first sub-spacer layer to form a first sub-spacer on the sidewall of the gate structure and on the source and drain regions.