Low-Energy Electron-Induced Decomposition and Reactions of Adsorbed Tetrakis(trifluorophosphine)platinum [Pt(PF₃)₄]

Abstract

Electron-beam-induced deposition (EBID), also referred to as focused electron-beam-induced processing (FEBIP), is a lowvacuum materials processing technique in which a focused electron beam is used to directly write nanometer-sized structures onto a substrate in a constant partial pressure of precursor molecules. 1À4 EBID has a unique and attractive combination of capabilities, including high spatial resolution and the flexibility to deposit self-supporting three-dimensional nanostructures on nonplanar surfaces. EBID offers a number of advantages compared to other vacuum-based nanofabrication strategies. EBID is capable of creating smaller features than ion-beaminduced deposition (IBID), with less amorphization and without ion implantation. 5À7 Although the resolution of EBID is comparable to that of electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL), 8,9 it needs no resist layers or etching step for pattern transfer. The advantages of EBID have also been recently been combined with those of atomic layer deposition (ALD) to create purely metallic but geometrically well-defined nanostructures. 10 Current applications of EBID include repairing masks used in UV lithography, 11À14 creating line gratings on vertical cavity surface emitting lasers, 15 and fabricating tips for scanning probe microscopy. 16,17

Substrate temperature and electron fluence effects on metallic films created by electron beam induced deposition

“…This step ensures that the effect of substrate temperature provides information only on the fate of those nonvolatile species deposited on the surface by electron beam reactions with the precursor. To accomplish this goal we have taken advantage of information acquired in our previous UHV studies, 16,19 which indicate that the initial electron induced reaction of the three precursor molecules [MeCpPtMe 3 , Pt(PF 3 ) 4 , and W(CO) 6 ] involves the ejection of gas phase CH 4 , PF 3 , and CO species, respectively. In typical EBID experiments this initial electron stimulated reaction corresponds to the electron stimulated deposition event that converts the transiently adsorbed precursor molecule into a surface bound species.…”

“…19 More prolonged electron exposures cause electron stimulated P-F bond cleavage within the Pt(PF 3 ) 3 . 19 This was verified experimentally by ensuring the intensity in the P(2p) region had decreased to 75% of the value measured after Pt(PF 3 ) 4 adsorption, and before the onset of electron irradiation.…”

“…The choice of these three molecules was predicated on their widespread use by the EBID community as precursors, and our understanding of the purely electron stimulated decomposition process. 7,8,10,11,16,19,[21][22][23][24][25][26][27][28][29][30][31][32] In addition, our results can be compared and benchmarked against compositional data that already exist from previous EBID studies where deposition was accomplished under more typical conditions. Our experimental approach involved exposing nanometer thick films of parent precursor molecules to different electron fluences.…”

Absolute cross sections for dissociative electron attachment and dissociative ionization of cobalt tricarbonyl nitrosyl in the energy range from 0 eV to 140 eV

“…To our knowledge, however, DEA has to date not been accounted for in MC simulations dealing with FEBID, and although it is clear that further studies are necessary to confirm their relevance and especially how the DEA processes are influenced by the supporting surface, recent investigations indicate strongly that DEA may play a pivotal role in FEBID. [21][22][23][24][25]46 In particular, this applies to the purity of the deposit and the broadening of the deposits beyond the diameter of the electron beam, which are currently the main challenges that need to be addressed to further enhance the applicability of FEBID as a standard tool in nano-fabrication. Like DEA, absolute cross sections for DI of relevant FEBID precursor molecules are scarce.…”

“…7,20 At those energies, dissociative electron attachment (DEA) is the only efficient fragmentation mechanism and, in that context, its potential role in FEBID has been discussed in some detail. [21][22][23][24][25] Although DEA is the only effective electron induced dissociation mechanism below the ionization limit of the respective molecules, SEs and BSEs, with incident energies close to and above the ionization limit of the respective molecules, can also cause fragmentation through dissociative ionization (DI). This is a non-resonant process, but can nonetheless be very efficient at fairly low incident energies (typically, in the range 10-50 eV).…”