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.