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A Benchmark of 300mm RP-CVD Chambers for the Low Temperature Epitaxy of Si and SiGe
摘要： we have assessed, in 300 mm Reduced Pressure – Chemical Vapour Deposition chambers from major suppliers, the advantages and drawbacks of disilane for the low temperature growth of Si and SiGe. Si growth rates are, for T < 575°C, approximately ten times higher with Si2H6 than with SiH4, which are in turn roughly ten times higher than with SiH2Cl2. For given GeH4 and Si precursor mass-flow ratios, lower Ge contents and much higher SiGe growth rates are obtained at 550°C, 20 Torr with Si2H6 than with SiH4 and especially SiH2Cl2. Growth rates (Ge concentrations) are with SiH4 and SiH2Cl2 lower (slightly lower) in Supplier A than in Supplier B chamber. The situation is the opposite with Si2H6. This is assigned to (i) a ~ 5°C offset between the two and (ii) effective precursor flows which are different, most likely due to chamber geometry differences. Growth rate activation energies and relationships linking Ge concentration to precursor mass-flow ratios are quite similar, however, making process transfer between the two rather easy. Finally, we have compared ex-situ “HF-Last” wet cleanings and in-situ surface preparation processes for Si surface conditioning prior to epitaxy. Surfaces are after the latter always under high purity N2. This results in a threshold H2 bake temperature (above which there is no O interfacial contamination anymore) which is shifted downwards by ~ 25°C (from 775°C down to 750°C). Below that threshold, O sheet concentrations are with in-situ processes typically one third those associated with “HF-Last” wet cleanings and epitaxial surfaces are smoother.
关键词： surface preparation,SiGe,silane,disilane,RP-CVD,low temperature growth,Si,dichlorosilane
更新于2025-09-23 15:21:01
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Thermal joining of thermoplastics to metals: Surface preparation of steel based on laser radiation and tungsten inert gas arc process
摘要： Laser-based joining is a potential key manufacturing process for realizing metal plastic hybrids. Therefore, surface preparation is essential to achieve a mechanical form fit. A new approach for surface preparation is based on a tungsten inert gas (TIG) arc process with anodic polarity. This TIG structure was characterized compared to fiber laser manufactured structures in cw and pw mode. The comparison of different preparations was based on pure ultimate tensile strength tests on spot joints. Finally, a transfer to overlap joints was successfully carried out and characterized by tensile shear tests using fiber reinforced plastics.
关键词： laser joining,surface preparation,laser welding,TIG welding,structured steel,metal-plastic-hybrid joints,dissimilar materials,lightweight design
更新于2025-09-12 10:27:22
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GeSn surface preparation by wet cleaning and in-situ plasma treatments prior to metallization
摘要： GeSn, a group IV binary alloy, is currently of high interest. Its use is envisioned in two kinds of applications: (i) as a source/drain compressive stressor in order to boost the hole mobility in short gate length Ge channel p-type MOSFETs [1] and (ii) as a direct-band-gap material for Si photonics, provided that the Sn content is higher than 10%, typically [2]. However, the fabrication of GeSn-based components faces major technological issues. First of all, as the lattice mismatch between Sn and Ge is large (14%) and the solubility of Sn in Ge low at thermodynamic equilibrium (< 1%), specific conditions have to be used for the epitaxial growth of high Sn content GeSn layers. Moreover, the fabrication of efficient ohmic contacts to receive and deliver power and signals is challenging. Ni-stanogermanides are currently under investigation in order to benefit from low contact resistivity (Rc) and sheet resistance (Rsh) in GeSn-based devices. The surface preparation of such metastable alloys will then be an unavoidable step. Whatever the targeted application, wet cleaning is indeed mandatory to remove particles, organic materials, metallic impurities and native oxides from the surface. Literature data on GeSn surface preparation prior to metallization is currently scarce [3], [4]. Based on the existing knowledge on pure germanium, we will likely have to cope with a high dissolution in oxidant solutions (GeO2 dissolution in water) and unstable surface preparations (high reactivity upon air and oxygen exposure). Ex-situ wet cleanings will likely suffer from a fast native oxide regrowth on the GeSn surface. In-situ plasma treatments in a chamber connected to the metal deposition chamber itself, i.e. without any air break, should enable to get rid of that problem. In this work, after a characterization of the native oxide formed upon air exposure of Ge0.85Sn0.15 alloys, we investigate the impact of i) wet chemistries, ii) plasma treatments and iii) “wet + plasma” combinations on GeSn surface oxide removal.
关键词： surface preparation,GeSn,metallization,wet cleaning,plasma treatments
更新于2025-09-09 09:28:46