Approaches to nanofabrication on Si(100) surfaces: Selective area chemical vapor deposition of metals and selective chemisorption of organic molecules

Abstract

Articles you may be interested inOxygen adsorption-induced nanostructures and island formation on Cu{100}: Bridging the gap between the formation of surface confined oxygen chemisorption layer and oxide formationThe selective removal of hydrogen from a passivated Si͑100͒ surface with an ultrahigh vacuum scanning tunneling microscope ͑STM͒ allows nanometer-sized ''templates'' of clean Si͑100͒ to be defined on an otherwise unreactive surface. Such depassivated areas have already been shown to react selectively with O 2 and NH 3 in preference to the surrounding H-terminated surface. This selectivity suggests two more sophisticated approaches to fabricating nanostructures with this technique: ͑1͒ selective metallization by thermal chemical vapor deposition, and ͑2͒ formation of ordered organic monolayers by reaction with specific organic molecules. In the first case, an intrinsic difference in the reaction rate of a metal precursor with the clean and H-terminated Si͑100͒ surface results in selective deposition of a metal on the STM-patterned area. In order to prevent hydrogen desorption and loss of selectivity, the metal precursor must dissociate its ligands at relatively low temperatures. In the second case, the patterned surface is exposed to an organic molecule expected to react in a site specific manner with unsaturated Si dimer sites. An example of this site selective reaction is the ͓2ϩ2͔ cycloaddition reaction between carbon-carbon double bonds and the Si dimer bond. Such reactions can result in the formation of spatially resolved nanometer-sized regions containing organic monolayers. In this article we describe progress toward the fabrication of nanostructures utilizing these two techniques. First, we discuss the use of a new amidoalane precursor for the selective chemical vapor deposition of aluminum on STM-patterned Si͑100͒ surfaces, as well as the selective patterning of a nucleation promoter, TiCl 4 , commonly used to initiate aluminum film growth. We also discuss the selective chemisorption of norbornadiene ͑bicyclo͓2.1.1͔ hepta-2,5-diene͒ on STM-patterned areas. STM images reveal the formation of a norbornadiene adlayer with indications of local ordering. Both of these methods show promise as techniques for the fabrication of nanostructures on Si͑100͒ surfaces.

STM-Induced Desorption and Lithographic Patterning of Cl–Si(100)-(2 × 1)

“…The lines here are not fully continuous due to Cl remaining along the path of the lithography, which appear as several darker, Cl-terminated dimers. The average depassivation fraction of Si dimers along these three lines is 0.66 (4). Lithographic parameters for this atomic precision, negative V B mode were varied in a manner similar to the studies represented in Fig.…”

Chemical manipulation of multifunctional hydrocarbons on silicon surfaces

“…The removal of surface hydrogen atoms and the produced structures, including the ones modified with rather complex molecules, could be investigated essentially at the same time by the same tool. Seminal work by the groups of Lyding, Avouris, Stokbro, Hersam and many others [186,268,[387][388][389][390][391][392][393][394][395][396][397][398][399][400] has paved the way for the selective chemistry that could be induced by the silicon surface sites of specific structure, the idea that was put forward in the late 90s [387,401]. From a single dangling bond produced by an STM tip, to lines of silicon surface dimers stripped of hydrogen, to complex patterns formed by dangling bonds of silicon surface atoms, these experiments provided an incredibly rich playing field for chemical modification of new type of substrates [31,402].…”

In situ spectroscopic ellipsometry study on the growth of ultrathin TiN films by plasma-assisted atomic layer deposition

“…43 As a consequence, the film nucleation is very slow on H-terminated c-Si, because the TiCl 4 molecules can only nucleate on surface defects. 16 The plasma-induced formation of the SiN x film creates surface groups such as NH x groups that are reactive to the TiCl 4 molecules and facilitates the film nucleation.…”