Effect of liquid additives in supercritical fluid deposition of copper for enhancing deposition chemistry

Momose, Takeshi; Ohkubo, T.; Sugiyama, Masakazu; Shimogaki, Yukihiro

doi:10.1016/j.tsf.2008.07.037

Cited by 17 publications

(9 citation statements)

References 30 publications

(43 reference statements)

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“…4,28 The presence of the b-Sn component has been attributed to the ability of certain solvents to cause a hydride reduction to the metal during thin lm formation as a result of their decomposition under the elevated temperatures in the reactor. [29][30][31] In cases where such peaks are apparent, such as high-temperature, oxygen decient AACVD conditions with EtOH carrier solvent, mixed phase lms are made.…”

Section: Synthesis and Characterisationmentioning

confidence: 99%

Enhanced transparent-conducting fluorine-doped tin oxide films formed by Aerosol-Assisted Chemical Vapour Deposition

2013

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We report a systematic study into the importance of carrier solvent on the Aerosol-Assisted Chemical Vapour Deposition (AACVD) of fluorine-doped tin oxide (FTO) films. In particular, the resultant effects on both the optical transparency and electrical conductivity properties are reported with optimised films showing figures-of merit significantly beyond commercial products. Depositions were carried out at substrate temperatures of 500, 550 and 600 C using either N 2 or air as the carrier gas. The carrier solvent was found to have a marked effect on film quality and performance characteristics. Hall Effect results indicate that use of propan-2-ol as carrier solvent and air as carrier gas gave the best performing n-type FTO thin films overall that exhibited high optical transparency (>80% at 550 nm) and resistivity values of 4 Â 10 À4 U cm, with charge carrier density and carrier mobility values of 4 Â 10 20 cm À3 and 39 cm 2 V À1 s À1 respectively, in addition to haze values of 10-15%. Such parameters are ideal for thin film solar cell applications and have significantly higher figures of merit compared to current commercial materials. Success of this method of deposition is attributed, in part, to a halide transfer reaction in which part fluorine substitution of the tin precursor occurs in the solvent resulting in a direct tin-fluorine bond. The work shows the key role carrier solvents play in AACVD in directing the system chemistry.

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Section: Synthesis and Characterisationmentioning

confidence: 99%

Enhanced transparent-conducting fluorine-doped tin oxide films formed by Aerosol-Assisted Chemical Vapour Deposition

2013

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“…57 Alcohols can also be used to reduce Cu(II) precursors, as demonstrated by several groups. 36,58 One challenge for the use of reactive depositions such as CVD, ALD, and SFD in interconnect structures has been 31,32 Inset is a comparison of nickelocene concentrations between the vapor phase and the solubility limits in scCO 2 at a CO 2 density of 0.55 g/cm 3 . 20 the lack of adequate adhesion to adjacent barrier layers.…”

Section: Metal and Metal Oxide Depositionmentioning

confidence: 99%

“…By contrast, attempts to deposit Cu by the thermal disproportionation of Cu(I) precursors in supercritical carbon dioxide in the absence of H 2 or other reducing agents yields copper oxides . Alcohols can also be used to reduce Cu(II) precursors, as demonstrated by several groups. , …”

Section: Applications In Device Fabricationmentioning

confidence: 99%

Supercritical Fluids for the Fabrication of Semiconductor Devices: Emerging or Missed Opportunities?

2009

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“…[33][34][35][36] The solvation effect of an SCF decreases the activation energies of possible reactions and can thereby enable lower process temperatures. These beneficial aspects of SCFD can be enhanced by controlling the reaction chemistry using carefully selected additives that take advantage of the (1) entrainer effect (increased solute solubility in an SCF) [37][38][39][40] and the (2) solvent effect (promotion of deposition reactions). 37,38 Metal film formation by SCFD, however, selectively occurs on conductive substrates, but not on insulators, making it difficult to apply SCFD to device fabrication, especially for MEMS devices.…”

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confidence: 99%

One-Step Fabrication of Copper Thin Films on Insulators Using Supercritical Fluid Deposition

Uejima

Momose

Sugiyama

et al. 2013

J. Electrochem. Soc.

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A one-step fabrication method for direct supercritical fluid deposition (SCFD) of Cu on insulators was developed. This overcomes the limitation of conventional SCFD, which cannot directly deposit Cu on insulators. In our one-step method, a relatively small amount of an Mn precursor was mixed with a Cu precursor to deposit a CuMn x O y composite layer on an insulative underlayer. This underlayer then acted as a buffer layer, allowing subsequent Cu deposition. This method successfully achieved Cu deposition on insulators, including SiO 2 , boron phosphorus silicon glass (BPSG), and Parylene. The superior conformal deposition ability of conventional SCFD was also demonstrated using our one-step method, where Cu was deposited uniformly on an overhung test structure. Detailed analysis revealed that our one-step method was initiated by deposition of MnO x , which could include Cu, resulting in CuMn x O y film formation, followed by Cu deposition. The amount of the MnO x deposited during Cu deposition was negligible due to the much lower growth rate of MnO x compared with Cu. This process is useful for the fabrication of electronic devices having complex features and comprising various materials. . This paper is part of the JES Focus Issue on Electrochemical Processing for Interconnects.Microfabrication technologies, such as deep reactive ion etching (DRIE), 1-4 have enabled the fabrication of three-dimensional (3D) complex structures with extremely high aspect ratios (HAR), above 50 for instance, on the surface of silicon wafers. Thin-film technologies that enable conformal coatings on these features have been applied to a variety of electronic devices, including microelectromechanical systems (MEMS), 5-7 dynamic random access memory (DRAM), 8-10 and through silicon via (TSV), 11,12 to exploit the large surface area and to functionalize the devices. Chemical vapor deposition (CVD), which is a technology having good step coverage, cannot meet these demands. Electroless deposition (ELD) is another candidate, which conventionally requires catalytic underlayer, and recently becomes possible on the insulating underlayers using Au nanoparticle catalyst. 13-15 ELD is a wet process, and thus advantageous in simplicity of equipment, while supercritical fluid deposition (SCFD), which is a focus of this paper, requires incidental facilities including a high pressure pump and a pressure control system to realize deposition under high pressure environment. Nevertheless, SCFD seems to have more possibility to achieve conformal deposition on extremely high-aspect-ratio features. Because step coverage is determined by the balance between the transportation of the precursor by diffusion within the trenches and consumption of the precursor on the side walls by deposition reactions, higher diffusivity in SCFD (10 −7 -10 −8 m 2 /s) compared with that in liquid solution of ELD (10 −10 m 2 /s) leads to higher step coverage.SCFD is a novel approach that achieves conformal deposition onto HAR features. This method uses the oxidation/reduction...

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Effect of liquid additives in supercritical fluid deposition of copper for enhancing deposition chemistry

Cited by 17 publications

References 30 publications

Enhanced transparent-conducting fluorine-doped tin oxide films formed by Aerosol-Assisted Chemical Vapour Deposition

Enhanced transparent-conducting fluorine-doped tin oxide films formed by Aerosol-Assisted Chemical Vapour Deposition

Supercritical Fluids for the Fabrication of Semiconductor Devices: Emerging or Missed Opportunities?

One-Step Fabrication of Copper Thin Films on Insulators Using Supercritical Fluid Deposition

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