A method of defining a gate structure for a MOSFET device featuring the
employment of dual anti-reflective coating (ARC) layers to enhance gate
structure resolution, and featuring a dry procedure for removal of all ARC
layers avoiding the use of hot phosphoric acid, has been developed. After
formation of a polysilicon layer on an underlying silicon dioxide gate
insulator layer, a capping silicon oxide, a dielectric ARC layer, and an
overlying organic ARC layer are deposited. A photoresist shape is formed
and used as an etch mask to allow a first anisotropic RIE procedure to
define the desired gate structure shape in the dual ARC layers and in the
capping silicon oxide layer. After removal of the photoresist shape and
the overlying organic ARC layer a second anisotropic RIE procedure is used
to define a desired polysilicon gate structure, with the second
anisotropic RIE procedure also resulting in the removal of the dielectric
ARC shape. A final hydrofluoric acid type solution is then used to remove
the capping silicon oxide shape as well as to remove the portions of the
silicon dioxide gate insulator layer not covered by the polysilicon gate
structure.
