DESIGN AND FABRICATION OF PLANAR INTERDIGITATED CAPACITORS

Abstract

The Planar oOlZology ii becomingC the 'bast build&# 14 blocks tczr nticroeleotrcziic *ircdtry which Wftnssed & revoiuticn n the Eletronics tryp Design and construction ttcJni uss of planar to d capacitors are attr.cting theattentionof m*z•y 3Ci*rLtict, and researchers as they are fiMiJ2g wide applications U the e tiy advancing rase*rcb and d*v.loefltsl areas like conventional grid integrated circuits,. nicrovave integrated ciro4 e md surtace scoustic wave design t€cIoiogy. firs: most widely ud types ct interdigitato structures ► toraed by eetabUsJg the gaoetreal tsbricsti.o technique for sianufacturing thin fUn inter- dgittsd cspacitor uing methanical mask ban been developed and repertad in this dissertation. T be proces developod is e+o . and jle in that It involves only vaoutt dapoBitton of a single netallised conductive 2*YX A= anti. Th other notabli features of the process are. (s) The conductor teri deposited y we 4 of the øubstrat., (b) Ko ulce r deposition (either of &te eotrio or conductive) is Involved thus making the process inexpensive., quicker $ easy and more reliable. (e) No photo masking technique is necessary for generating the patterns. Several capacitors With i values of 5 pf, 8 pf, 10 pf, 22 pf and .2 pf have been designed and fabricated on substrates of microscopic glass and 99.5)'. alma at this laboratory to check the reproducibility of the fabriea- ted structures. fliough• the patterns generated by the mechanical masks are not as acct rate as those that can be obtained by either photo'-1 thograpbio . technique or by ash finer masks. made with the help of , photoengraving process 9 yet the results obtained are good and found to fit well to withi ±IbY..of the datigasd values.., The frequency response of the parameters of these capacitors namely the capacitance and loss factor has been studied experimentally over .a frequency band of I KBZ to 30 Ni. The measure& data indicated that the capatWauce values remain fairly constant upto 30 r (with alumina) and 20 I! (with glass). _ The loss. factor being fairly constant aptb I Min in both cases, started increasing thereafter. It s also observed that altuina substrates exhibit lover ]ssss.compared to glass ones: The adherence of the alum ism f .1rn to the. aiming ,a substrates (sapp Led by MIS TEKNISS Is found to b