Electron beam induced deposition of low resistivity platinum from Pt(PF3)4

Abstract

Articles you may be interested inModular ultrahigh vacuum-compatible gas-injection system with an adjustable gas flow for focused particle beam-induced depositionThe authors have deposited Pt from Pt͑PF 3 ͒ 4 using a focused 10 keV electron beam ͑scanning electron microscopy͒ in an FEI 620 dual beam system and measured the resistivity and composition of the deposits. To measure resistivity, lines of Pt were deposited across four gold fingers and the cross-sectional area of the lines was measured by focused ion beam sectioning. The resistivity varies between about 30 and 650 ⍀ cm and is orders of magnitude lower than the resistivity achieved by e-beam-induced deposition using the usual organometallic precursor, ͑methylcyclopentadienyl͒ trimethyl platinum. In general, the higher the beam current the lower the resistivity. They have used wavelength dispersive x-ray analysis to measure the composition of rectangles deposited with various beam currents. Typical at.% values of ͑Pt:P:F͒ are 81:17:2 and 58:32:10. Minimum linewidth that they have deposited is 80 nm, and with a stationary beam of 2.8 nA they have deposited a pillar of 135 nm in diameter. They have also deposited Pt structures on freestanding carbon nanotubes and have used the deposits to contact nanofibers. Electron-beam-induced deposition of a "good" metal is particularly useful in geometries where standard lithography is awkward, such as making contacts to fibers or nanotubes randomly dispersed on a surface or freestanding.

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

“…This is the reason why deposits can be created from Pt(PF 3 ) 4 that contain only Pt and P atoms. 11,14,22 In addition to the effect that substrate temperature has on film composition, our results show that the binding energy of platinum atoms in the Pt(4f) region decreases systematically as the substrate temperature increases above 0 C [Figs. 2 and 5(c)], an effect which is consistent with an increase in metallic character.…”

“…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.…”

“…8 For example, using the Me 2 Au(tfac) precursor Koops et al showed that depositions carried out at a substrate temperature of 80 C resulted in EBID materials with lower resistivity compared to deposits created on substrates maintained at room temperature. 13 The lower resistivity was ascribed to the fact that the atomic percentage of Au in the deposits increased significantly when the substrate temperature during deposition was increased (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) at. % at room temperature vs 70 at.…”

“…6,7 In situ techniques focus mainly on changing the electron beam parameters, namely, the spot size, dwell time, or current density. [8][9][10][11][12] Another in situ approach to improve purity has involved performing EBID on a heated substrate. 8 For example, using the Me 2 Au(tfac) precursor Koops et al showed that depositions carried out at a substrate temperature of 80 C resulted in EBID materials with lower resistivity compared to deposits created on substrates maintained at room temperature.…”

Electrical properties of platinum interconnects deposited by electron beam induced deposition of the carbon-free precursor, Pt(PF3)4

“…31 In this study, a relatively low beam current of $1.4 nA allows adequate decomposition of the Pt precursor over a time period of approximately 3 min, which compares favorably to the very high currents used by Ervin and coworkers (13-46 nA) to decompose the same precursor. 35 While deposition times can be reduced at high beam currents, beam sensitive samples may suffer beam damage resulting in higher resistivities. The only varying parameter in our experiments during deposition was the fluctuating residual gas in the vacuum chamber, which should be kept to a minimum to ensure reproducible results and to minimize contamination of the deposited Pt structures.…”