Non-volatile memory and integrated memory and peripheral circuitry
fabrication processes are provided. Sets of charge storage regions, such
as NAND strings including multiple non-volatile storage elements, are
formed over a semiconductor substrate using a layer of charge storage
material such as a first layer of polysilicon. An intermediate dielectric
layer is provided over the charge storage regions. A layer of conductive
material such as a second layer of polysilicon is deposited over the
substrate and etched to form the control gates for the charge storage
regions and the gate regions of the select transistors for the sets of
storage elements. The first layer of polysilicon is removed from a
portion of the substrate, facilitating fabrication of the select
transistor gate regions from only the second layer of polysilicon.
Peripheral circuitry formation is also incorporated into the fabrication
process to form the gate regions for devices such as high voltage and
logic transistors. The gate regions of these devices can be formed from
the layer forming the control gates of the memory array.