Outgassing Behavior of Organic Spin-on-Glass Modified by Ion Implantation

Abstract

The difficulty in the use of spin-on-glass (SOG) for multilevel interconnections leads to the requirement of higher-temperature (800–850°C) curing of the material, since the low-temperature annealed SOG may result in a significant amount of moisture during subsequent heat cycles leading to reliability problems. However, the application of an ion implantation method can improve the outgassing behavior of SOG annealed at 425°C. The temperature of the ion implantation treatment is made lower so as to be compatible with aluminum which is used as the conductive material. Ion implantation treatment using P+ (phosphorous) and As+ (arsenic) which are applied to the siloxane-type SOG is proposed in this paper. The thermal desorption analysis from experiments shows that the implanted SOG has a much lower water content and does not have a moisture desorption peak up to 600°C for both P+ and As+ implantations. The combination of the thermal curing and ion implantation treatments is beneficial for reducing the residual moisture content and promoting the thermal stability of SOG films. In addition, the results show that the implanted SOG is more insensitive to moisture absorption than the unimplanted SOG under the condition of 48-h air exposure. This implies that both water reabsorption and desorption performances of SOG can be further improved by ion implantation.