Fabrication method of flash memory device with L-shaped floating gate

A fabrication method of a flash memory with a L-shaped floating gate, said fabrication method including the following steps:

• providing a semiconductor substrate having a defined active region, wherein further comprising an oxide layer deposited on a surface of said semiconductor substrate;
• forming a patterned first dielectric layer on said oxide layer to expose said active region;
• depositing a first polysilicon layer on said semiconductor substrate to cover said active region and said first dielectric layer;
• depositing a second dielectric layer on a surface of said first dielectric layer;
• performing an anisotropic etching step to etch said second dielectric layer to form a dielectric spacer at a gibbous portion of said first dielectric layer;
• using said dielectric spacer as a mask to etch said first polysilicon layer to form a L-shaped poly spacer in said active region between said first dielectric layer for use as a floating gate and then removing said first dielectric layer;
• performing ion implantation to said semiconductor substrate to form a source and a drain of ion doped regions;
• depositing an isolating dielectric layer on said semiconductor substrate to cover said L-shaped poly spacer and said oxide layer;
• and
• forming a defined second polysilicon layer on said isolating layer for use as a control gate, wherein said second polysilicon layer is covering a gibbous portion of said L-shaped poly spacer.