CMOS compatible on-chip decoupling capacitor based on vertically aligned carbon nanofibers

One-dimen­sion­al car­bon nano­struc­tures have been known and fab­ric­ated for more than a hun­dred years and were ori­gin­ally On-chip decoup­ling capa­cit­or of spe­cif­ic capa­cit­ance 55 pF/​μm² (foot­print area) which is 10 times high­er than the com­mer­cially avail­able dis­crete and on-chip (65 nm tech­no­logy node) decoup­ling capa­cit­ors is presen­ted. The elec­trodes of the capa­cit­or are based on ver­tic­ally aligned car­bon nan­ofibers (CNFs) cap­able of being integ­rated dir­ectly on CMOS chips. The car­bon nan­ofibers employed in this study were grown on CMOS chips using dir­ect cur­rent plasma enhanced chem­ic­al vapor depos­ition (DC-PECVD) tech­nique at CMOS com­pat­ible tem­per­at­ure. The car­bon nan­ofibers were grown at tem­per­at­ure from 390 °C to 550 °C. The capa­cit­ance of the car­bon nan­ofibers was meas­ured by cyc­lic voltam­metry and thus com­pared. Futher­more the capa­cit­ance of decoup­ling capa­cit­or was meas­ured using dif­fer­ent voltage scan rate to show their high charge stor­age cap­ab­il­ity and finally the cyc­lic voltam­metry is run for 1,000 cycles to assess their suit­ab­il­ity as elec­trode mater­i­al for decoup­ling capa­cit­or. Our res­ults show the high spe­cif­ic capa­cit­ance and long-term reli­ab­il­ity of per­form­ance of the on-chip decoup­ling capa­cit­ors. Moreover, the spe­cif­ic capa­cit­ance shown is lar­ger for car­bon nan­ofibers grown at high­er temperature.