Abstract
We performed extremely low-energy 16O+ implantation at 10 keV (Rp ∼ 25 nm) followed by annealing aiming at directly synthesizing an ultrathin Si layer separated by a buried SiO2 layer in Si(001) substrates, and then investigated feasible condition of recrystallization and stabilization of the superficial Si and the buried oxide layer by significantly low temperature annealing. The elemental compositions were analyzed by Rutherford backscattering (RBS) and secondary ion mass spectroscopy (SIMS). The crystallinity of the superficial Si layer was quantitatively confirmed by ananlyzing RBS-channeling spectra. Cross-sectional morphologies and atomic configurations were observed by transmission electron microscope (TEM). As a result, we succeeded in directly synthesizing an ultrathin single-crystalline silicon layer with ≤20 nm thick separated by a thin buried stoichiometric SiO2 layer with ≤20 nm thick formed by extremely low-energy 16O+ implantation followed by surprisingly low temperature annealing at 1050∘ C.
Highlights
It is recognized that ultrathin SOI and buried oxide (BOX) structures make it possible for further high-density device integration, which is applied to fabricate a high performance complementary metal-oxide-semiconductor field-effect-transistor (CMOSFET) in ultra-large scale integration (ULSI) technology beyond ordinary devices based on bulk Si substrates.[4,5,6,7]
There are some kinds of methods to synthesize the SOI/BOX structure: such as a separation by implanted oxygen (SIMOX) followed by high-temperature annealing, a wafer bonding method with sequential thinning process represented by Bond and Etch-back SOI (BESOI), and “Smart-Cut technology”
We discussed the phenomenon happening at such high-temperature and high-energy implantation, and concluded that some oxygen species accompanying Si were supposed to be desorbed during such a high-temperature implantation
Summary
Electronic devices fabricated on Si-on-insulator (SOI) structure separated by a buried oxide (BOX) layer from a Si substrate show great features of high performance, low-energy consumption, and high-radiation hardness, compared to those formed on a bulk Si substrate.[1,2,3] It is recognized that ultrathin SOI and BOX structures make it possible for further high-density device integration, which is applied to fabricate a high performance complementary metal-oxide-semiconductor field-effect-transistor (CMOSFET) in ultra-large scale integration (ULSI) technology beyond ordinary devices based on bulk Si substrates.[4,5,6,7] Especially, the thin SOI and BOX layer with thickness of less than 20 nm is desirable for suppressing short channel and self-heating effect which are the crucial issues on high-integrated nanoscale devices today.[8,9,10,11,12]. There are some kinds of methods to synthesize the SOI/BOX structure: such as a separation by implanted oxygen (SIMOX) followed by high-temperature annealing, a wafer bonding method with sequential thinning process represented by Bond and Etch-back SOI (BESOI), and “Smart-Cut technology”. In the ordinary SIMOX preparation, defects were induced in the superficial Si layers during a large amount of oxygen implantation; as a result, the quality of the SOI/BOX layer formed by the SIMOX method is inferior to that formed by the wafer-bonding method. Extremely high-temperature annealing at more than 1300◦C was quite dispensable to recover the induced defects and stabilize the SOI/BOX structures. We performed extremely low-energy oxygen implantation at 10 keV, whose projected range is estimated to be ∼25 nm, to directly synthesize an ultrathin SOI and a BOX layer in silicon substrates. We determined the plausible condition to form the ultrathin SOI/BOX layers by significantly low-energy O+-implantation and sequential annealing
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