this oxidation barrier is deposited and patterned in accordance with conventional methods the oxidation barrier defines what is to be the active region of a field effect transistor device it is also noted that substrate 10 possesses a substantially planar surface and may in fact comprise silicon material doped with a particular polarity dopant the oxidation barrier preferably comprises a layer 11 of silicon oxide over which is disposed a coextensive layer of silicon nitride 12 for example in one embodiment of the present invention substrate 10 comprises a n n epitaxial wafer processing typically begins with the growth of a thin layer of stress relief oxide 11 followed by low pressure chemical vapor deposition of silicon nitride the workpiece is then masked with photoresist so as to selectively define the field oxide regions and then the overlying silicon nitride layer is etched to define the active regions the resulting structure is seen in cross sectional view in fig1 after the silicon nitride is patterned to define the active areas the photoresist material is removed and an approximately 1 micron thick field oxide layer is thermally grown this results in the formation of silicon oxide regions 14 as seen in fig2 it is noted that during oxidation of the silicon substrate the oxide of silicon swells so as to take up more room this results in relatively thick silicon oxide regions at.