Electrochemical anodizing technique was used to form an interlevel alumina insulator for multilevel aluminum metallization. The low dielectric constant of about 2.4 was reached by chemical etching of porous alumina films in anodizing solution. The interlevel insulator based on porous alumina had the following parameters measured: the breakdown voltage was more than 400 V, the leakage current at 15 V applied voltage was less than 10-9A/cm2. The developed processing technique was tested for CMOS submicron technology. The fabricated aluminum-porous alumina structure demonstrated a good chemical and thermal stability, excellent adhesion to underlying and top layers.
Lazarouk, S., Katsouba, S., Leshok, A., Demianovich, A., Stanovski, V., Voitech, S., … Ponomar, V. (2000). Porous alumina as low-ε insulator for multilevel metallization. Microelectronic Engineering, 50(1–4), 321–327. https://doi.org/10.1016/S0167-9317(99)00298-1