Fabrication of a Nanoscale Single-Crystalline Silicon Thin Film on Insulator

Abstract

One-dimensional nanostructure materials on a desired substrate were fabricated by a hydrogen ion-exfoliation-based wafer bonding approach integrated with a sacrificial layer. The nanoscale defining thickness is exactly achieved by the employment of polysilicon as a sacrificial layer. The hydrogen implanted device wafer was bonded to a Pyrex 7740 wafer and then the polysiliconoxide-silicon sandwich structure layer was exfoliated and transferred onto the Pyrex wafer by a thermal-microwave hybrid method. The thickness of the transferred single-crystal silicon layer was measured at 100 nm by transmission electron microscopy.Modern thin-film technology evolved into nanoscale is a "have to" technique to fabricate advanced electronic and optoelectronic products such as high-speed integrated circuit ͑IC͒ devices, photoelectron devices, and so on. For high-speed ICs, wireless communication, or laser-optics applications, a nanoscale single-crystal quality thin film is the requirement for high reliability, high yield, long lifetime, accuracy, and reproduction. A single-crystal ultrathin film on a dissimilar substrate can combine the advantage properties of two materials to offer a superior work character; for example, the silicon on insulator ͑SOI͒ provides transistors to have subthreshold swings ͑down to the ideal value of about 60 mV/dec͒, smaller source/drain junction and junction-perimeter capacitances, and low current leakage, which allows faster transistor operation and low power consumption to decrease heat generation and prolong the operation time. 1 Such nanoscale single-crystal thin-film SOI material is now in high demand by leading IC manufactures for the development of nanoscale node technology in device fabrication. Until now, the most widespread method for producing a single-crystal thin-film SOI has been Smart-Cut technology. 2 Because of the light mass of hydrogen ion for the technology, it is difficult to fabricate a nanoscale thick film without an additional thinning process. It is a challenge to still keep the uniformity of the thin-film thickness after the additional thinning process. There are two main methods to thin the thickness of the thin film fabricated by the Smart-Cut process to the nanoscale. One is layer-by-layer thinning of the transferred layer from its top face using oxidation-etch technology 3 or the oxygenation-depth-control polishing stop technique, 4 and another one employs a built-in etch-stop layer to achieve an etch-back thinning-based approach 5 developed by IBM.A so-called Si-Sandwich process was developed by Usenko et al. 6 to acquire a nanothick SOI layer by first implanting heavy ions such as silicon ions into a silicon wafer to form a buried crystal-disorder layer as a hydrogen trap layer. The silicon-asimplanted wafer is hydrogenated by an electrolysis step to create a buried hydrogen-filled layer for obtaining a similar hydrogen-ionsplit effect to peel the crystal layer from the buried hydrogenated layer in silicon wafer.However, to avoid complex steps but precisely control t...

Thermal Stress Induced Thin Film Transfer from Single-crystal Silicon Layer on Sapphire Substrate

“…This study tends to apply SOS to thin film solar cell by thin film transfer technique. The thin film transfer can be used to fabrication of nano-scale single crystalline silicon thin film [2]. The most well-known thin film transfer technique is the Smart-Cut R [3] or Ion-Cut R [4] process.…”