Inherent selective pulsed chemical vapor deposition of aluminum oxide in nm scale

Abstract

Inherent selective pulsed chemical vapor deposition (CVD) of aluminum oxide on Si and SiO2 in preference to SiCOH has been studied. SiCOH is alkyl (-CxHy) terminated SiO2, which was used as a non-reactive surface. For aluminum oxide deposition, pulsed CVD processes using aluminum tri sec-butoxide (ATSB) and trimethylaluminum (TMA) were tested. ATSB alone can induce a pulsed thermal CVD reaction to selectively deposit aluminum oxide at 300 °C sample temperature; ∼4 nm of aluminum oxide were selectively deposited on Si and SiO2 in preference to SiCOH. By adding a periodical pulse of TMA during ATSB pulses, higher selectivity was achieved with ∼12 nm and ∼14 nm of aluminum oxide on Si and SiO2 with around 0.4–0.5 nm root mean square (RMS) roughness at 330 °C. The high selectivity persisted on the nanoscale: STEM showed that ∼10 nm of aluminum oxide could be selectively deposited on nanoscale patterned features. The selectively deposited AlOx films showed low k (∼4) dielectric performance with low leakage (around 10−6 A/cm2 at ± 2 V for a 15 nm thick film). This selective aluminum oxide pulsed CVD process has the potential to be applicable in nanoscale fabrication, such as low k spacer and etch stop layer.