Electron beam induced deposition at elevated temperatures: compositional changes and purity improvement

Abstract

Thermally assisted electron beam induced deposition can result in an improvement of the purity of nano-scale depositions. Six commonly used organic precursors were examined: W(CO)(6), TEOS (tetraethylorthosilicate), MeCpPtMe(3), Co(CO)(3)NO, Co(2)(CO)(8), and Me(2)Auacac. The last two precursors were also tested on two different instruments to confirm reproducibility of the results. The influence of the substrate temperature on the composition of the deposition has been quantified systematically in the temperature range 25-360 °C. It has been shown that most purities improve when applying an elevated temperature, while the shape of the deposition remains intact. The purity improvement is achieved at the cost of a lower deposition yield. The amount of improvement is different for each precursor. Within the maximum temperature range of 360 °C, the best improvement was found for W(CO)(6): from 36.7 at.% at 25 °C to 59.2 at.% at 280 °C. For both cobalt precursors an additional transition region between patterned electron beam induced deposition (EBID) and thermal thin film growth has been identified. In this region seeded growth occurs with strongly increased growth rates.

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

“…1(a) and also with recent results obtained by Mulders et al [ Fig. 1(b)], who studied the composition of EBID films created from MeCpPtMe 3 in a SEM as a function of substrate temperature in the range 25 C to 360 C. 15 Indeed, despite the different deposition conditions and analytical techniques (XPS in the present study, and EDS in the study by Mulders), a comparison of Figs. 1(a) and 1(b) shows that the chemical composition of the EBID materials is very similar in the two studies.…”

“…Another factor which must be considered in translating the effect of substrate temperature on chemical composition determined from the UHV experiments described in this study to experiments conducted under dynamic, steady state conditions is the upper temperature limit (or ceiling) imposed by the onset of conformal CVD deposition involving the precursor. For example, in the case of MeCpPtMe 3 , spontaneous deposition was observed in electron microscopes at 360 C; 15 consequently, EBID experiments using this precursor should not be conducted at substrate temperatures at or even slightly below this temperature, to ensure the spatial integrity and specificity of the deposit.…”

“…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.…”

“…This study revealed that increases in metallic content can occur when the substrate temperature was increased, although the importance of this processing variable depended on the precursor. 15 For example, TEOS and MeCpPtMe 3 showed no increase in metallic content when the substrate temperature was increased. In contrast, the metallic content of EBID films created from W(CO) 6 increased from 36.7 at.…”

Mass Spectrometry Study of the Temperature Dependence of Pt Film Growth by Atomic Layer Deposition

“…However, adsorption of the precursor has been reported even at room temperature. 23 Furthermore, it is known that plasma assisted ALD of Pt is possible at 100…”