Patent ID: 7737031

Claim:
A method of making an inverse-t shaped floating gate in a non-volatile memory cell, comprising: forming a tunnel oxide layer on a substrate; depositing a first polysilicon layer over the layer of tunnel oxide, the first polysilicon layer comprising: undoped, p-doped or n-doped or combinations thereof; depositing a second polysilicon layer over the first polysilicon layer, the second polysilicon layer comprising: p-doped or n-doped or combinations thereof, and the second polysilicon layer being more heavily doped than the first polysilicon layer; applying a mask over the second polysilicon layer; forming a trench at least partially extending through the first and second polysilicon layers and the tunnel oxide and the trench at least partially extending into the substrate; stripping the mask from the second polysilicon layer and forming an oxide layer on a top surface and sidewalls of the second polysilicon layer during a controlled defume/strip process carried out in oxygen plasma; and removing the oxide from the top surface and sidewalls of the second polysilicon layer.