Separation by plasma implantation of oxygen with plasma immersion ion implantation to form silicon-on-insulator.

摘要

With the growing importance of silicon on insulator (SOI) substrates for IC fabrication, high- volume and low-cost SOI substrate fabrication processes are desirable. The separation by plasma implantation of oxygen (SPIMOX) is proposed as a high throughput and an economic SOI substrate fabrication process.;SPIMOX is a variation of the existing separation by implantation of oxygen (SIMOX) process. In the existing process, the high dose of oxygen to form the buried oxide (BOX) is implanted using a conventional implanter (1.8 x 1018 cm-2 for a BOX thickness of 400 nm). The wafer is then annealed at a high temperature of 1300°C for six hours to form the BOX. The implantation current in a conventional implanter is limited. Since the SIMOX process uses conventional implanters, the throughput of wafers is low.;SPIMOX substitutes plasma immersion ion implantation (PIII) for the oxygen implantation. The PIII process yields high implantation rates and the wafer throughput is independent of the wafer size. Moreover, the equipment is simpler to install and maintain compared to a conventional implanter.;An operational phase-space for the implantation in SPIMOX has been identified. The composition of the plasma used for the implantation has been analysed. An annealing sequence for the BOX formation has been determined. The process window for the dose and annealing temperature in SPIMOX has. also been identified. The formation of a continuous BOX has been confirmed with XTEM and SIMS characterisation.;Electrical evaluation of the SPIMOX wafer has been performed by measuring the characteristics of devices fabricated on them. The transistor parameters for the n-channel MOSFETs on SPIMOX have been evaluated. The transistors exhibit characteristics specific to SOI devices.;This work proves the feasibility of the SPIMOX process and demonstrates it as a promising process for economic SOI fabrication.