Semiconductor device manufacturing: process – Formation of semiconductive active region on any substrate
Reexamination Certificate
1999-06-08
2001-11-06
Mulpuri, Savitri (Department: 2812)
Semiconductor device manufacturing: process
Formation of semiconductive active region on any substrate
C117S087000, C438S962000
Reexamination Certificate
active
06313015
ABSTRACT:
FIELD OF INVENTION
This invention relates to a method of using silicon monoxide or suboxide for the growth of high-purity silicon nanowires and silicon nanoparticle chains in bulk-quantity.
BACKGROUND OF THE INVENTION
Materials engineering at the nanometer scale can provide smaller devices than those currently available. In particular, research on semiconductor nanostructures with size-dependent optical and electronic properties, such as quantum-dots, one-dimensional quantum wire transistors and light emitting devices with extremely low power consumption is motivated by potential applications. Silicon is a material of great interest for nanostructures because of its important role in the field of microelectronics.
Since the 1960's, silicon whiskers grown by the vapor-liquid-solid (VLS) reaction have been extensively studied. After the VLS technique, many efforts have been made to further improve the synthesis of silicon nanowires by employing different techniques, such as photolithography technique combined with etching and scanning tunneling microscopy. These methods are tedious and normally produce only a limited number of strands of nanowires. Recently, silicon nanowires have been synthesized by laser ablation of metal-containing silicon targets (Wang, et al., Chemical Physics Letter, 283, p.368, 1998; Zhang et al., Applied Physics Letter, 72, p.1835, 1998; Morales et al., 279, p. 208, 1998). However, since metals were used as a catalyst, this method is in fact an extension of the VLS technique. The drawbacks of the VLS technique in producing nanowires are (1) contamination by the metal catalyst and (2) the extremely low yield of production, Therefore, one of the challenging issues in the field of silicon nanostructures has been the synthesis of high-quality, high purity silicon nanowires in large quantities.
SUMMARY OF INVENTION
The present invention provides a method for producing large quantity of silicon nanowires and nanoparticle chains in a large- area from silicon monoxide or suboxide on any kind of substrates without using metal or other catalysts.
According to the present invention there is provided a method of forming silicon nanowires comprising activating vapor phase silicon monoxide or suboxide (ie Si
x
O where x≧1) carried in an inert gas.
The vapor phase silicon monoxide or suboxide may be obtained directly from a gaseous source or from a solid source. When a solid source is used, the solid source may comprise silicon monoxide itself, or may comprise silicon dioxide and silicon that may react together (possibly with the addition of Ge) to produce silicon monoxide.
Activation of the vapor phase may be by one of a number of methods including thermal excitation, laser ablation, chemical vapor deposition, plasma or magnetron sputtering.
The inert gas is preferably selected from the group consisting of neon, argon and helium and mixtures thereof.
The ambient conditions, notably temperature and pressure may determine the diameter of the nanowires formed. In preferred embodiments during silicon nanowire formation the pressure is maintained in the range of from 1 to 800 Torr. Preferably the silicon nanowires are formed on a substrate maintained at from 800 to 1000° C.
The present invention may also extend to the formation of nanowires of materials other than silicon, and accordingly viewed from another aspect the present invention provides a method of forming nanowires of M where M is selected from the group consisting of silicon, germanium, carbon or silicon carbide comprising activating vapor phase M
x
O (where x≧1) in an inert gas.
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Wang et al “Si Nanowires Grown From Silicon-Oxide”, Chemical Physics Letters 299 (1999) 237-242.*
Alfredo M. Morales, et al.; “A Laser Ablation Method for the Synthesis of Crystalline Semiconductor Nanowires”;Science; Jan. 9, 1998; vol. 279, pp. 208-211.
Y.F. Zhang, et al.; “Silicon nanowires prepared by laser ablation at high temperature”;Applied Physics Letters; Apr. 13, 1998; vol. 72, No. 15, pp. 1835-1837.
N. Wang, et al.; “Transmission electron microscopy evidence of the defect structure in Si nanowires synthesized by laser ablation”;Chemical Physics Letters; Feb. 13, 1998; pp. 368-372.
Bello Igor
Lee Chun-Sing
Lee Shuit-Tong
Wang Ning
City University of Hong Kong
Merchant & Gould P.C.
Mulpuri Savitri
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