Efficient Process for Direct Atomic Layer Deposition of Metallic Cu Thin Films Based on an Organic Reductant

Tripathi, T. S.; Karppinen, Maarit

doi:10.1021/acs.chemmater.6b04597

Cited by 24 publications

(27 citation statements)

References 61 publications

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“…The films were highly crystalline and therefore the surface roughness was too high for the XRR data to be used for film thickness determination; however, the XRR data were used to estimate the film densities from the critical angles. The film thicknesses were estimated with AFM (TopoMetrix Explorer) using the cantilever tip jump technique; the as‐deposited films were stable even when left in ambient conditions for several days. The surface topography and RMS roughness measurements were performed using the same AFM in the contact mode.…”

Section: Methodsmentioning

confidence: 99%

Atomic Layer Deposition of Conducting CuS Thin Films from Elemental Sulfur

Tripathi

Lahtinen

Karppinen

2018

Adv Materials Inter

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Copper sulfide thin films have been fabricated by various deposition techniques, such as chemical vapor deposition, [15] sputtering, spray pyrolysis, [16,17] chemical bath deposition, [18,19] and electrochemical methods. [20][21][22] However, in most cases the required control over the film stoichiometry and phase composition is poorly achieved due to the coexistence of several stable and metastable copper sulfide phases. [23] Moreover, fabrication of continuous copper sulfide coatings with a well-controlled morphology on highaspect-ratio nanostructures has remained a challenge. It is here in particular where the atomic layer deposition (ALD) technique could provide us with clear advantages over the other thin-film technologies for the deposition of high-quality copper sulfide thin films for various advanced applications including the photovoltaics. [17,24,25] Atomic layer deposition is based on sequential and self-limiting gas-surface reactions and is known to yield exceptionally homogeneous coatings in atomic-scale precision independent of the substrate geometry.The vast majority of the metal sulfide ALD processes is based on metal-organic precursors together with hydrogen sulfide H 2 S as the source of sulfur; [26] the same applies to the reported copper sulfide ALD processes as well (see Table 1). The main merit of H 2 S is that it is highly reactive toward common metal precursors. However, H 2 S is a flammable, corrosive, and highly toxic gas, and its incorporation in the ALD technology presents several serious technical challenges. The special precautions required for the safe use of H 2 S may even be one of the reasons why only 16 metal sulfide ALD processes have been so far reported during the half a century long ALD history. [26] Another drawback of the H 2 S-based ALD processes is the slowness of these processes, see, e.g., the growth rate values given in Table 1 for the copper sulfide processes. Moreover, majority of the reported copper sulfide processes yields Cu(I) sulfide as the main phase; hence, there is a clear interest in a new robust and efficient ALD process for high-quality Cu(II) sulfide thin films. [27] Despite the fact that some of the early ALD processes employed elemental sulfur instead of H 2 S as the sulfur source, [35] to the best of our knowledge no sulfur-based ALD processes have been reported for copper sulfide thin films. Here, we present a simple and efficient low-temperature ALD process for the deposition of high-quality p-type conducting CuS thin films from copper acetyl acetonate and elemental sulfur precursors, as a highly viable solution to the challenges discussed above.A facile, yet precisely controlled and efficient atomic layer deposition (ALD) process is reported for high-quality copper(II) sulfide thin films based on elemental solid sulfur as the source for sulfur; Cu(acac) 2 (acac: acetylacetonate) is used as the copper precursor. In the deposition temperature range as low as 140-160 °C, the process proceeds in an essentially ideal ALD manner and yields single-phase C...

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Section: Methodsmentioning

confidence: 99%

Atomic Layer Deposition of Conducting CuS Thin Films from Elemental Sulfur

Tripathi

Lahtinen

Karppinen

2018

Adv Materials Inter

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“…Then, comparing the Cu(dmap)2+HQ process developed here with the similar process where Cu(acac)2 was used as the copper precursor, it was found that while the Cu(acac)2+HQ process yielded metallic Cu films thorough a wide deposition temperature range, 51 the Cu(dmap)2+HQ process is temperature dependent such that it results in metallic Cu films only at the higher deposition temperatures; at temperatures below 120 o C the process successfully yielded hybrid Cu-HQ films. Also importantly, the as-deposited amorphous hybrid films were strongly air and moisture sensitive and crystallised upon the reaction with water.…”

Section: Discussionmentioning

confidence: 94%

“…In the case of HQ as the organic precursor, it was interesting to observe the effect of the deposition temperature: at the higher deposition temperatures the Cu(dmap)2+HQ process yielded metallic Cu films like in our previous study with Cu(acac)2 as the copper precursor. 51 However, the low sublimation temperature of Cu(dmap)2 allowed us to carry out depositions also in the lower temperature range of 100-120°C where amorphous Cu-organic films were obtained. With ODA, amorphous hybrid films were obtained at deposition temperatures up to ~220 °C, whereas at 240 °C the Cu(dmap)2+ODA process too yielded metallic Cu films.…”

Section: Resultsmentioning

confidence: 99%

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Atomic/molecular layer deposition of Cu–organic thin films

et al. 2018

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“…9 It was observed that the basics of nickel thin-film deposition using plasma-enhanced ALD are transferable from the sapphire substrate to aluminum oxide foams. In addition to this particular application, the ability to deposit pure metallic thin films has several applications in metallization, 43,44 solar cell cathodes, 45 and solid oxide fuel cells, 46 among others.…”

Section: Resultsmentioning

confidence: 99%

Growth and Characterization of Metastable Hexagonal Nickel Thin Films via Plasma-Enhanced Atomic Layer Deposition

Motamedi

Bosnick

Cui

et al. 2017

ACS Appl. Mater. Interfaces

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There is a great interest in various branches of the advanced materials industry for the development of novel methods (and improvements to existing ones) for the deposition of conformal ultrathin metallic films. In most of these applications, like enhanced solar absorbers and microelectronics, achieving the capacity to deposit a conformal thin film on a three-dimensional structure is an important condition. Plasma-enhanced atomic layer deposition (ALD) is known for its potential for growth of conformal thin films with a precise control over the thickness and its capability for deposition at relatively low temperatures (below 500 °C). This study evaluates the potential of plasma-enhanced ALD for growth of conformal nickel thin films, using bis(ethylcyclopentadienyl)nickel and nitrogen/hydrogen plasma as precursors. A comprehensive analysis of the structure, composition, and physical properties of the films was performed. The results indicate that conformal nickel films with low levels of impurity were successfully deposited on sapphire. The films had a roughness of R = 1.5 nm and were seen to be under strain. The deposited nickel had a hexagonal crystal structure, with a random in-plane orientation of the grains, while the grains had their c-axes oriented along the normal to the interface. These results pave the way for conformal low-temperature deposition of high-quality nickel thin films on three-dimensional structures.

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Efficient Process for Direct Atomic Layer Deposition of Metallic Cu Thin Films Based on an Organic Reductant

Cited by 24 publications

References 61 publications

Atomic Layer Deposition of Conducting CuS Thin Films from Elemental Sulfur

Atomic Layer Deposition of Conducting CuS Thin Films from Elemental Sulfur

Atomic/molecular layer deposition of Cu–organic thin films

Growth and Characterization of Metastable Hexagonal Nickel Thin Films via Plasma-Enhanced Atomic Layer Deposition

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