CMP process for selectively-grown carbon nanotubes in via structure

We have developed a CMP process providing a short polishing time and sufficient uniformity that is applicable to 300 mm scale carbon nanotube (CNT) via integration. To achieve our target, we have developed a new CMP process to make selectively grown CNT in a via hole. Spin on carbon (SOC)film was coated to protect nickel (Ni) catalyst and titanium nitride (TiN) film inside the via hole during SOC-CMP. The SOC-CMP process was used to perform two-step polishing to remove Ni catalyst and TiN film from the field area. CNT-CMP polishing time was reduced from 1690 sec to 200 sec and the yield ratio improved to 100%. CNT-CMP performance improved to a level usable for practical use by selectively growing CNT only from the via. We also evaluated the behavior of CNT-CMP during polishing using a damascene pattern wafer. Step height (Step height means a step between the wiring area and field area) occurred when CNT-SOG (spin-on glass) composite film was appeared upper the via hole but was reduced by concentrating the polishing pressure to project the CNT-SOG composite film. This result indicates that CNT-SOG composite film was polished by mechanical force.