Fabrication of silicon-on-insulator (SOI) and high-k materials using plasma technology

Plasma-based technologies such as plasma immersion ion implantation and deposition (PIII&D) are widely used. In addition to the capability to alter the materials surface, novel microelectronic structures can be fabricated. In this invited paper, our recent research activities on the application of plasma technologies to microelectronics are reviewed. Silicon-on-insulator (SOI) is replacing conventional bulk silicon substrates in many high speed, low power microelectronic devices because it possesses advantages such as reduction of parasitic capacitance, excellent sub-threshold slope, elimination of latch up, and resistance to radiation. However, wider applications of SOI in microelectronics are hampered by the self-heating effects caused by the poor thermal conductivity of the buried silicon dioxide layer. We have produced alternative buried insulators such as diamond-like carbon that possesses better thermal conductivity than conventional silicon dioxide using plasma immersion ion implantation and deposition (PIII&D) and successfully fabricated SOI structures with improved thermal stability. The use of low-energy plasma hydrogenation to substitute for the more costly beam-line hydrogen ion implantation in the ion-cutting layer transfer technology is also discussed. In the 45 nm node, high-k dielectrics are used as a replacement for SiO₂. Plasma immersion ion nitridation is used to produce thin HfO₂ films with improved thermal and electrical properties. Co-doping with fluorine and nitrogen is also found to effectively suppress the interfacial compounds between ZrO₂ and silicon and the resulting dielectric properties are improved. Recent progress is reviewed in this paper.