formed from vapor deposited aluminum or sputtered al cu alloy and will typically have a thickness of about 5000 u00e5 in order to protect the resistive material 24 and electrodes 28 and 30 during subsequent processing steps it is preferred to deposit a blanket protective coating 26 over the resistive material 24 and electrodes 28 and 30 on the dielectric layer 10 the protective coating may be deposited or grown using any of the well known chemical vapor deposition techniques suitable protective coatings include si 3 n 4 sio 2 sic and the like with the preferred being si 3 n 4 and sic the total thickness of the protective coating is preferably about 5000 u00e5 subsequent to protectively coating the resistive material 24 and electrodes 28 and 30 select portions of the photoresist layer 14 are patterned and developed thereby exposing a portion 16 of the mask layer 8 fig4 d the positioning of the photoresist mask used to expose the portion 16 of the mask layer 8 is determined by reference to the previously drilled alignment holes 38 the exposed portion 16 of the mask layer 8 may then be etched away using a plasma or wet etch process such as a buffered hydrofluoric acid solution thereby forming a plurality of elongate marks 18 in the mask layer 8 after forming the elongate marks 18 the photoresist layer 14 is removed by means of acids organic solvents such as acetone or chemical combustion in an oxygen glow discharge chamber fig4 e once the elongate marks 18 are formed in the mask layer 8 the silicon substrate 2 is.