Characterization in Silicon Processing

Figure

2.8 TEM

cross section

of a

polycide line after

oxi-

dation

showing,

in the

bottom third

of the mi-

crograph,

a

separation between

the

polysilicon

(second band from

the

left)

and the

tungsten

suicide (third band from

the

left).

The

oxide

growth between

the

separated layers

is

also

clearly

seen.

Once

the polycide lines are formed, the next step is to encase them in an oxide

film

formed by thermal oxidation. Thermal oxidation of the polycide lines provides

an

Si02

film on the exposed polysilicon and, due to the thermodynamics of the

system,

an

Si02

film is also grown on the

WSi

2

layer.

The silicon required for

Si02

formation on the

WSi

2

come ...