Low Average Surface Roughness Research Articles

In Situ Characterization of Triboelectrochemical Effects on Topography of Patterned Copper Surfaces

The topographic response of patterned copper surfaces to chemical–mechanical polishing (CMP) was investigated using a triboelectrochemical approach. Experimental methods include using a combined system containing a tribometer and a potentiostat. Results showed that more step height reduction and lower average surface roughness were obtained via CMP in acidic than in alkaline slurry. The increased contact area between wafer, pad, and abrasives was associated with the increase in friction. It was found that pH-dependent oxide formation and removal dominate the step height reduction for both acidic and alkaline slurries. The in situ approach pinpointed interactions between mechanical stimulation, chemical reaction, and electrochemical passivation. This research is beneficial to understanding triboelectrochemistry in Cu chemical–mechanical polishing of patterned wafers, an important application in semiconductor manufacturing.

Effect of indium doping on physical properties of nanocrystallized SnS zinc blend thin films grown by chemical bath deposition

SnS:In thin films have been successfully prepared on Pyrex substrates using low cost chemical bath deposition technique with different indium concentrations (y=[In][Sn]=4%,6%,8%,and10%). The structure, the surface morphology, and the optical properties of the SnS:In films were studied by x-ray diffraction, scanning electron microscope, atomic force microscopy, and spectrophotometer measurements. In order to obtain a thickness of the order of 308 ± 10 nm for potential applications in solar cell devices, a multilayer deposition has been prepared. It is found that the physical properties of tin sulphide are affected by indium concentration. In fact, x-ray diffraction study showed that better crystallinity in zinc blend structure with preferential orientations (111)ZB and (200)ZB was obtained for y equal to 6%. According to the AFM analysis, we remark that low average surface roughness value of SnS(ZB) thin film is obtained with In concentrations equal to y = 6%. Energy dispersive spectroscopy showed the existence of In, Sn, and S in the films. Optical analyses by means of transmission T(λ) and reflection R(λ) measurements show 1.57 eV as an optical band gap value of SnS:In(6%), which is lower than the previously obtained value (1.76 eV) for undoped tin sulphide. In doped tin sulphide exhibits a high absorption coefficient 2.5 × 106 cm−1, indicating that SnS:In can be used as absorber thin layer in photovoltaic structure such as SnS:In/ZnS/SnO2:F and SnS:In/In2S3/SnO2:F, where ZnS and In2S3 are chemically deposited as described in a previous work. In this study, the hetero-junctions SnS/In2S3:Al and SnS/ZnS:In are also investigated.

Changes of semifusinite and fusinite surface roughness during heat treatment determined by atomic force microscopy

Abstract This study describes changes of surface roughness of semifusinite and fusinite as an indicator of structural alteration resulting from heat treatment at 400–1200 °C. Surface roughness has been investigated by atomic force microscopy of inertinite concentrates from coking coals (vitrinite reflectance Rr = 1.07%–1.41%) from the Upper Silesian Coal Basin of Poland (Namurian C — Westphalian A). Unheated fusinite has a higher surface roughness than semifusinite from the same coal. The average surface roughness of semifusinite decreases with the Swelling Index of the parent coal. Heating increases the surface roughness of semifusinite and fusinite. Increase in the average surface roughness is stronger for semifusinite than fusinite and correlates to increasing reflectance of these macerals. The surface roughness of semifusinite correlates to the relative mass loss of the inertinite concentrates during heating. After heating to 1200 °C fusinite has a lower average surface roughness than semifusinite from the same coal. Consequently, average surface roughness can be used as a measure of structural alteration of inertinite group macerals during heat treatment.

Effect of copper doping on physical properties of nanocrystallized SnS zinc blend thin films grown by chemical bath deposition

SnS: Cu thin films have been successfully prepared on Pyrex substrates using low cost chemical bath deposition (CBD) technique with different copper doped concentration (y = [Cu]/[Sn] = 5%, 6%, 8%, 9% and 10%). The structure, the surface morphology and the optical properties of the SnS:Cu films were studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and spectrophotometer measurements, respectively. To obtain a thickness of the order of 780 ± 31 nm for absorber material in solar cell devices, a system of multilayer has been prepared. It is found that the physical properties of tin sulphide are affected by Cu-doped concentration. In fact, X-ray diffraction study showed that better cristallinity in zinc blend structure with preferential orientations (111)ZB and (200)ZB, was obtained for y equal to 6%. According to the AFM analysis we can remark that low average surface roughness (RMS)value of SnS(ZB) thin film obtained with Cu-doped concentrations equal to y = 6%, is about of 54 nm. Energy dispersive spectroscopy (EDS) showed the existence of Cu in the films. Optical analyses by means of transmission T(λ) and reflection R(λ) measurements show 1.51 eV as a band gap value of SnS:Cu(6%) which is nearly equal to the theoretical optimum value of 1.50 eV for efficient light absorption. On the other hand, Cu-doped tin sulphide exhibits a high absorption coefficient up to 2 × 106 cm−1, indicating that SnS:Cu can be used as an absorber thin layer in photovoltaic structure such as SnS:Cu/ZnS/SnO2:F and SnS:Cu/In2S3/SnO2:F, where ZnS and In2S3 are chemically deposited in a previous studies.

The Effects of Machining Parameters on Cutting Forces, Surface Roughness, Built-Up Edge (BUE) and Built-Up Layer (BUL) During Machining AA2014 (T4) Alloy

Tool wear, formed in cutting tool during machining processes, affects the surface roughness of the work piece, cutting forces and other output parameters. The effects of the machining parameters cutting speed (Vc) and the feed rate (f) on built-up edge (BUE), built-up layer (BUL), main cutting force (Fc), and surface roughness (Ra) is investigated in this study. The effects of the cutting parameters on cutting force and surface roughness has been examined by the use of Variance Analysis (ANOVA); and their optimum and critical cutting parameters were determined accordingly. AA2014 aluminum alloy was machined with uncoated carbide tools using Computer Numerical Control (CNC) turning machine under dry cutting conditions. Four different cutting speeds (200 m/min, 300 m/min, 400 m/min, and 500 m/min), five different feed rates (0.10 mm/rev, 0.15 mm/rev, 0.20 mm/rev, 0.25 mm/rev, and 0.30 mm/rev) and a constant depth of cut were selected as the machining parameters. BUE and BUL in the cutting tool were formed most at cutting speed 200 m/min and feed rate 0.30 mm/rev. The lowest cutting force was determined as 137 N at cutting speed 500 m/min and feed rate 0.10 mm/rev. The lowest average surface roughness, however, was determined as 0.93 µm at 500 m/min cutting speed and feed rate 0.10 mm/rev.

Surface roughness of glazed feldspar, alumina, and zirconia-based ceramics

The aim of this study was to compare the mean surface roughness (Ra) of feldspar-, alumina-, and zirconia-based ceramics, testing the hypothesis that the feldspathic ceramics have lower average surface roughness (Ra) than the ceramics used for infrastructure. Eight disk specimens (5mm in diameter; 2mm in thickness) of each ceramic material were fabricated according to the manufacturer’s specifi cations: V7-feldspathic veneer ceramic (Vita VM7); VA-feldspathic veneer ceramic (Vitadur-α); IA-slip casted, glass-infi ltrated alumina-based ceramic (Vita In-Ceram Alumina); IZS-slip casted, glass-infi ltrated zirconia-reinforced alumina-based ceramic (Vita In-Ceram Zirconia); IZB-dry-pressed block ofglass-infi ltrated zirconia-reinforced alumina-based ceramic (Vita In-Ceram Zirconia 2000 for Cerec InLab). All materials were glazed as recommended by the manufacturer. Four Ra readings (Mitutoyo SJ 400) per specimen were performed, averaging the value per specimen (n=8). Ra values were statistically analyzed using one-way ANOVA and Tukey test (α=0.05). V7 showed the lowest mean Ra value (0.43±0.07 μm) compared to the other ceramics. There were no statistical differences between the mean Ra values of VA (0.94±0.2 μm), IA (0.7±0.13 μm), IZS (0.98±0.3 μm) and IZB (0.75±0.4 μm). The testing hypothesis was partially accepted. V7 showed a smoother ceramic surface than the VA. There were no statistically differences between the mean Ra value of the high crystalline content ceramics (IA, IZS, IZB).

Fabrication of a polymeric tapered HARMs array utilizing a low-cost nickel electroplated mold insert

A simple low-cost technique has been developed to fabricate a mold insert for replicating polymeric tapered high aspect ratio microstructures. A backside exposure technique is used to first obtain a tapered sidewall structure as an electroplating mold in SU-8 photoresist on a glass wafer. Nickel electroplating is utilized to form the mold insert. The lowest average surface roughness of the nickel mold insert on the side that interfaces with the glass wafer during electroplating is measured to be 7.02 nm. A novel technique involving use of titanium putty is introduced here to reduce cost and effort required to fabricate the mold insert. Replication of tapered microstructures in polymeric materials utilizing the fabricated mold insert is demonstrated here in polydimethylsiloxane by a direct molding process and in polymethyl methacrylate by hot embossing. The fabrication details for the mold insert are described. Advantages and disadvantages of the use of titanium putty for achieving superior metal surface finish are given.

The effect of coating material and geometry of cutting tool and cutting speed on machinability properties of Inconel 718 super alloys

In this study, the effects of cutting tool coating material and cutting speed on cutting forces and surface roughness are investigated. For this purpose, nickel based super alloy Inconel 718 is machined at dry cutting conditions with three different cemented carbide tools in CNC lathe. Metal removing process is carried out for five different cutting speeds (15, 30, 45, 60, 75 m/min.) while 2 mm depth of cut and 0.20 mm/rev feed rate are to be constant. Main cutting force, F c is considered to be cutting force as a criterion. In the experiments, depending on the tool coating material, lowest main cutting force is found to be 506 N at 75 m/min with multicoated cemented carbide insert whose top layer is coated by Al 2O 3. Lowest average surface roughness (0.806 μm) is obtained at the cutting speed of 15 m/min with single coated (TiN) cemented carbide inserts.

The effect of sample preparation technique on determination of structure and nanomechanical properties of human cementum hard tissue

The mechanical properties of a tissue can be evaluated by determining the response of the structure to mechanical loading. This can be accomplished only when the tissue has been prepared with minimum to no artifacts, thus preserving its structure. In this study it was hypothesized that the structure of cementum is inhomogenous, contributing to a significant variation in mechanical properties of cementum. Therefore, the goals of the study were to identify potential artifacts generated by conventional sample preparation techniques such as polishing and ultrasectioning and subsequently characterize the prepared specimens using an atomic force microscope (AFM) and an AFM-nanoindenter. Comparisons between cryofractured, ultrasectioned and polished specimens concluded that ultrasectioned surfaces have significantly lower average surface roughness ‘ R a’ ( p<0.05). Microstructure of ultrasectioned specimens characterized using an AFM illustrated Sharpey's fibers (SF) and intrinsic fibers (IF) running perpendicular and parallel to the root surface similar to the observed microstructure of cryofractured cementum. In addition, a 10–50 μm wide cementum dentin junction (CDJ) was distinctly observed in the ultrasectioned specimens but not in polished specimens. The SF and CDJ illustrated relatively higher levels of hydrophilicity under wet conditions. The observed inhomogenous microstructure of the ultrasectioned specimens led to a broader range of nanomechanical properties (modulus: 14.2–25.9 GPa; hardness: 0.48–1.09 GPa). However, masking of the same regions such as SF and CDJ due to smeared cementum in polished specimens resulted in a narrower range of nanomechanical properties (modulus: 18.2–20.8 GPa; hardness: 0.79–0.89 GPa). This effect is most noticeable under wet conditions for ultrasectioned specimens (modulus 2.6–10.9 GPa; hardness 0.05–0.30 GPa) compared to the polished specimens (modulus 12.2–14.5 GPa; hardness 0.33–0.45 GPa). Cementum also was shown to be highly viscoelastic, especially when hydrated. The results suggest ultrasectioning of cementum was superior to polishing preparation technique since it allowed visualization of cementum structures similar to cryofractured specimens while providing a flat surface necessary for AFM-based nanoindentation techniques. Additionally, the structural inhomogeneity observed within ultrasectioned cementum contributed to a broader range of mechanical properties.

Surface structuring and phase formation in thin metallic layers deposited at various temperatures

AbstractScanning electron microscopy, atomic force microscopy and x‐ray diffraction analyses were performed for the study of the influence of substrate temperature during deposition on the surface structuring and phase formation on thin metallic double layers. Thin layers of Au, Al and Cr were deposited at 150 and 300 °C on 30 nm thick Cu layers evaporated on Si (100) wafer substrates. Possible applications of such layers are Raman‐active surfaces and model layers for diffusion experiments. The topographical investigation revealed an increase of surface structuring with temperature that is related to the formation of intermetallic and oxide phases. At 150 °C deposition temperature, the average roughness (Ra) of the films was determined to be 2–3 nm and the surfaces appeared smooth. In agreement with previous ion beam analysis measurements, a significant surface roughness occurred at 300 °C, depending on the type of the metallic films. The lowest average surface roughness value was measured for the Al/Cu/Si system (Ra = 14.1 nm) and, about double the roughness was measured for the Au/Cu/Si and Cr/Cu/Si layer systems. In contrast, for single Cu layers a high value of Ra = 93.0 nm was determined. The combined analyses showed that the formation of intermetallic phases such as AlCu and CuAl2, reduces a surface roughening. However, the formation of oxide phases such as CuO2, increases, the average surface roughness. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Properties of electroless and electroplated Ni–P and its application in microgalvanics

Composition, microstructure, surface morphology, mechanical properties and electrochemical behaviour of electroless (el) and electroplated (ep) Ni–P deposits are studied using XPS, SEM–EDX, AFM, nanoindentation measurements, cyclic voltammetry and capacitance measurements. Ni–P layers were compared with ep Ni films and bulk Ni. Ni–P layers prepared by both techniques contain 12–14 wt% phosphorus, present in oxidation states of P 0 and P 3−. El and ep Ni–P deposits are amorphous and are characterised by a relatively low average surface roughness (2 and 4 nm, respectively). The ep layers possess a rhythmic-lamellar microstructure indicating a periodic change of electrodeposition conditions. The el Ni–P layers do not show such laminated structure but exhibit small surface pores, which are absent in the ep layers. Comparable values for the hardness and the reduced elasticity modulus of el and ep coatings are determined from the nanoindentation data. The observed small differences indicate that the mechanical properties of Ni–P deposits depend not only on the phosphorus content but also on the deposit microstructure. Microelectrochemical measurements with the so-called droplet cell show that the electrochemical behaviour of both el and ep Ni–P coatings is practically identical and does not depend on the location on the sample surface. Evolution of O 2 and H 2 on Ni–P are similar to pure Ni (ep and bulk), but the corrosion resistance in acid solution is much better. The very similar properties and electrochemical behaviour of el and ep Ni–P deposits suggest that both materials are suitable for various applications in microsystem technology. For different substrates and microstructures of different size and geometry, deposition conditions have still to be optimised.

00/02262 Interactions between coal and biomass when cofiring

This study describes changes of surface roughness of semifusinite and fusinite as an indicator of structural alteration resulting from heat treatment at 400–1200 °C. Surface roughness has been investigated by atomic force microscopy of inertinite concentrates from coking coals (vitrinite reflectance Rr = 1.07%–1.41%) from the Upper Silesian Coal Basin of Poland (Namurian C — Westphalian A). Unheated fusinite has a higher surface roughness than semifusinite from the same coal. The average surface roughness of semifusinite decreases with the Swelling Index of the parent coal. Heating increases the surface roughness of semifusinite and fusinite. Increase in the average surface roughness is stronger for semifusinite than fusinite and correlates to increasing reflectance of these macerals. The surface roughness of semifusinite correlates to the relative mass loss of the inertinite concentrates during heating. After heating to 1200 °C fusinite has a lower average surface roughness than semifusinite from the same coal. Consequently, average surface roughness can be used as a measure of structural alteration of inertinite group macerals during heat treatment.