Tilt-angle ion implant to improve junction breakdown in flash memory application

An optimum implant angle method of forming a DDD (Doubly Doped Drain) in a stacked flash memory cell comprising the steps of:

• providing a silicon substrate having a plurality of active and field regions defined;
• forming a gate oxide layer over said substrate;
• forming a floating gate over said thick gate oxide layer;
• forming an inter-gate oxide layer over said floating gate;
• forming a stacked control gate over said inter-gate oxide;
• forming oxide spacers on sidewalls of said stacked gate;
• performing a first lightly doped implantation with an optimum tilt-angle;
• and
• performing a second heavily doped implantation with an optimum tilt-angle.

An optimum implant angle method of forming a DDD (Doubly Doped Drain) in a flash memory cell comprising the steps of:

• providing a substrate having active and passive regions defined;
• forming a plurality of gates over said substrate;
• performing a first lightly doped implantation with an optimum tilt-angle to form a junction of said DDD in said flash memory cell;
• performing a second heavily doped implantation with an optimum tilt-angle to form a surface region of said DDD in said flash memory cell;
• and
• performing a drive-in diffusion of said doubly doped drain, DDD.