Microelectronic Engineering 50 (2000) 349–355 www.elsevier.nl / locate / mee Integration of HSQ in the direct-on-metal approach for 0.25-mm technology * T. Gao , A. Witvrouw, B. Coenegrachts, C. Bruynseraede, M. Van Hove, K. Maex IMEC Kapeldreef 75, B-3001 Leuven, Belgium Abstract The spin-on low-k material coated directly on the metal lines, which is called the direct-on-metal (DOM) approach, has been investigated with respect to issues about the intraline capacitance, the intraline leakage current, metal corrosion, unlanded vias, and electromigration lifetime. The results indicate that DOM can be successfully integrated with less process steps and better performance.  2000 Elsevier Science B.V. All rights reserved. Keywords: HSQ, Direct-on-metal approach, Spin-on-polymers 1. Introduction Spin-on-polymers (SOP) are widely used in the industry today for local planarization on inter-metal dielectric layers (IMD). Some SOP materials, such as methyl silsesquioxane (MSQ) and hydrogen silsesquioxane (HSQ), have lower relative permittivity which makes them more attractive. The SOP direct-on-metal (DOM) approach, which has less process steps and lower intraline capacitance, has been investigated for quite a long time (Fig. 1). SOP materials are considered as ‘dirty’ materials with plenty of moisture. Without the protection of the oxide liner, the metal might corrode when it is exposed to the SOP. Intraline leakage current would also be larger if metal (Al) diffuses into SOP. There is also concern that the electromigration lifetime of metal lines without an oxide liner could be worse. We found that by choosing the right SOP material and the right process, the problems of corrosion and leakage current can be solved. It is also found that the DOM approach can increase the electromigration lifetime and can improve the yield and the performance of unlanded vias significantly. *Corresponding author. E-mail address: teng@imec.be (T. Gao) 0167-9317 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0167-9317(99)00302-0