Particle-in-cell and TAMIX simulation of the hydrogen plasma immersion ion implantation ion-cut process

Silicon-on insulator (SOI) is an attractive material compared with bulk silicon substrate for high speed, low power, low voltage complementary metal oxide semiconductor (CMOS) integrated circuits. A bond-cut process, commercially referred to as Smart-Cut^TM developed by SOITEC, has provided excellent SOI wafers. One of the critical steps of Smart-Cut is to implant a fairly high dose of hydrogen into the wafer to form a plane along which the wafer can crack. Conventional beam-line ion implantation can be replaced by plasma immersion ion implantation (PIII) to achieve a higher throughput and lower cost. For hydrogen PIII/bond-cut, the coexistence of H⁺, H₂ ⁺, and H₃ ⁺ in the plasma tends to spread the implanted hydrogen profile that cracking may not occur uniformly. Hydrogen plasma immersion ion implantation (PIII) into a 200 mm diameter silicon wafer placed on top of a cylindrical stage has been numerically simulated by the particle-in-cell (PIC) method. The plasma consists of three hydrogen species H⁺, H₂ ⁺ and H₃ ⁺ in different ratio. The retained dose and sputtering loss are calculated by TAMIX. The highest retained dose is found for the H⁺ ion whereas half of the hydrogen atoms are not retained when H₃ ⁺ is implanted. The combined effect of the three species show a maximum non-uniformity in the retained dose of 11.5% along the radial distance. The depth profile is shallower at the edge but within a 6.375 cm radius, the depth profile is fairly uniform with the difference less than 5%.