Fabricating high-dielectric constant oxides on semiconductors using a GE buffer layer

DETAILED DESCRIPTION A Ge buffer layer directly or indirectly on Si oxidizes much less readily and can be used to prevent or minimize the formation of the low dielectric constant layer.
An epitaxial Ge layer on Si provides a good buffer layer which is compatible with Si and also many oxides.
Unlike other buffer layers, Ge is a semiconductor (it can also be doped to provide a reasonably highly conductive layer) and is compatible with Si process technology.
The epitaxial growth of Ge on top of the ferroelectric or high-dielectric constant oxide is also much easier than Si which makes it possible to form three dimensional epitaxial structures.
The Ge buffer layer can be epitaxially grown on the Si substrate allowing the high dielectric constant oxide to be epitaxially grown on the Ge and hence epitaxially aligned to the Si substrate.
The epitaxial Ge layer allows ferroelectrics to be directly grown on Si wafers to form non-volatile non-destructive read out memory cells.
The Ge buffer layer will also increase the capacitance of large dielectric constant oxide films compared to films grown directly on Si.
A Ge buffer layer on the Si or GaAs substrate allows many more oxides to be epitaxially grown on it because of the much smaller chemical reactivity of Ge with oxygen compared to Si or GaAs with oxygen.
Generally the prior art conductive materials suggested for interfacing with high dielectric constant oxides in semiconductor circuitry either have reacted with the high dielectric constant oxides or with the semiconductor and/or have not provided a diffusion barrier between the high dielectric constant oxides and semiconductor material.
As, noted, the integration of oxides on GaAs is even harder than Si because the GaAs is unstable in O.
sub.
2 at the normal growth temperatures of high-dielectric constant oxide (450.
degree.
C.
-700.
degree.
C.
).
A epitaxial Ge buffer layer solves this problem and simplifies the integration of ferroelectrics on GaAs for the same applications as listed above.
This is a method for fabricating a structure useful in semiconductor circuitry