Stylus Profiler Research Articles

Negatice Stiffness Vibration Isolation Technology for Nanotechnology

Abstract It wasn't too long ago that making the decision where to locate your scanning probe microscope was a simple one put it in the basement where the ambient vibration was minimized. But recently, with nanotechnology applications growing exponentially, scientists and engineers are putting their equipment in a multitude of locations where vibration noise is significantly high. Scanning probe microscopes, interferometers and stylus profilers are being sited in locations that pose a serious challenge to vibration isolation. Additionally, in an effort to keep their nano-equipment costs as low as possible by cutting out the peripherals, many academics and industries are not adequately providing for vibration isolation on their ultra-sensitive nano-equipment that they are putting into their facilities.

White Light Scanning Interferometry Adapted for Large-Area Optical Analysis of Thick and Rough Hydroxyapatite Layers

Understanding the mechanisms of biomineralization continues to be an important area of research in physics, chemistry, materials science, medicine, and dentistry due to its importance in the formation of bones, teeth, cartilage, etc. Stimulated by these fascinating natural examples, as well as by certain others such as shells and corals, attempts are being made to develop synthetic, biomimetic nanocomposites by simulating the basic principles of biomineralization. We have grown bio-like hydroxyapatite layers in vitro on substrates of stainless steel, silicon, and silica glass by using a biomimetic approach (i.e., immersion in a supersaturated simulated body fluid). Hydroxyapatite is one of the most common natural biomaterials and an important structural component of bones and teeth. Metal substrates are of interest for hard tissue implants, while semiconductors and glasses are under investigation for their use as biosensors. Using classical techniques such as stylus profiling, atomic force microscopy (AFM), and scanning and transmission electron microscopy (SEM and TEM), it was found difficult, ambiguous, destructive, or time-consuming to measure the topography, thickness, and profile of the grown heterogeneous, thick, and rough hydroxyapatite layers. On the other hand, coherence probe microscopy based on white light scanning interferometry and image processing provides rapid, contactless measurements of surface roughness and does not need any sample preparation. The results obtained have shown a typical layer thickness of up to 20 microm and an average root-mean-square (rms) roughness of about 4 mum. The hydroxyapatite investigated in this work presents nonetheless a challenge for this technique because of its semi-translucency, high surface roughness, and the presence of cavities formed throughout its volume. This results in a variable quality of fringe pattern, ranging from classical fringes (on a smooth surface) to complex fringes displaying properties of white light speckle (on a rough surface), together with multiple fringe signals along the optical axis in the presence of buried layer interfaces, which in certain configurations affect the axial and lateral precision of the measurement. In this paper we present the latest results for optimizing the measurement conditions in order to reduce such errors and to provide additional useful information concerning the layer.

Comparison of optical and stylus methods for measurement of surface texture

Optical methods are increasingly used for measurement of surface texture, particularly for areal measurements where the optical methods are generally faster. A new Working Group under Technical Committee (TC) 213 in the International Organization for Standardization is addressing standardization issues for areal surface texture measurement and characterization and has formed a project team to address issues posed by the optical methods. In this paper, we review the different methods of measuring surface texture and describe a classification scheme for them. We highlight optical methods and describe some of their characteristics as well as compare surface-profiling results obtained from three optical methods with those obtained from stylus profiler instruments. For moderately rough surfaces (Ra ≈ 500 nm), roughness measurements obtained with white light interferometric (WLI) microscopy, confocal microscopy, and the stylus method seem to provide close agreement on the same roughness samples. For surface roughness measurements in the 50 to 300 nm range of Ra, discrepancies between WLI and the stylus method are observed. In some cases the discrepancy is as large as about 75% of the value obtained with the stylus method. By contrast, the results for phase shifting interferometry over its expected range of application are in moderately good agreement with those of the stylus method.

Thinning of N-face GaN (0001 ¯) samples by inductively coupled plasma etching and chemomechanical polishing

The processing of N-polar GaN (0001 ¯) samples has been studied, motivated by applications in which extensive back side thinning of freestanding GaN (FS-GaN) substrates is required. Experiments were conducted on FS-GaN from two commercial sources, in addition to epitaxial GaN with the N-face exposed by a laser lift-off process. The different types of samples produced equivalent results. Surface morphologies were examined over relatively large areas, using scanning electron microscopy and stylus profiling. The main focus of this study was on inductively coupled plasma (ICP) etch processes, employing Cl2∕Ar or Cl2∕BCl3Ar gas mixtures. Application of a standard etch recipe, optimized for feature etching of Ga-polar GaN (0001) surfaces, caused severe roughening of N-polar samples and confirmed the necessity for specific optimization of etch conditions for N-face material. A series of recipes with a reduced physical (sputter-based) contribution to etching allowed average surface roughness values to be consistently reduced to below 3nm. Maximum N-face etch rates of 370–390nm∕min have been obtained in recipes examined to date. These are typically faster than etch rates obtained on Ga-face samples under the same conditions and adequate for the process flows of interest. Mechanistic aspects of the ICP etch process and possible factors contributing to residual surface roughness are discussed. This study also included work on chemomechanical polishing (CMP). The optimized CMP process had stock removal rates of ∼500nm∕h on the GaN N face. This was much slower than the ICP etching but showed the important capability of recovering smooth surfaces on samples roughened in previous processing. In one example, a surface roughened by nonoptimized ICP etching was smoothed to give an average surface roughness of ∼2nm.

Wet chemical etching of ZnO film using aqueous acidic salt

FeCl 3·6H 2O was used in the wet etching of single crystalline ZnO films. The method has great effects on the suppression of the “W” shaped etching profile usually observed when ZnO films were etched by acid. “U” shaped profile and smooth surface morphology were obtained under a wide range of etching rate, as confirmed by stylus profiler and scanning electron microscopy. The ferric deposition detected by the X-ray photoelectron spectra is speculated to be responsible for the formation of suitable solution hydromechanical parameters. The deposited layers can be removed easily by ultrasonic treatment, which makes the process easily controllable. These results show that this method is promising for processing ZnO-based optoelectronic devices.

ELECTRICAL AND OPTICAL PROPERTIES OF MULTILAYER SOL GEL ZnO COATINGS

Multilayer transparent conducting zinc oxide films have been prepared on boro-silicate substrates by the commercially sol gel dip coating process. Each layer was fired at 550°C in a conventional furnace for 15 min. The final coatings were then tempered under a flux of forming gas ( N 2/ H 2) at 400°C for 2 h. The coatings were characterized by surface stylus profiling and optical spectroscopy (UV-NIR). Results show that (1) ZnO films with electrical resistivity of 6×10-4 Ω· cm , free carrier mobility of approximately 77 cm 2/ V · s and free carrier density of approximately 6.14×1019 cm -3 are obtained for multilayers 310 nm and (2) the transmittance is approximately 60.4% and the reflectance is nearly 34.7% are obtained at a wavelength of 800 nm when the thickness of the ZnO multilayers is 310 nm. The crystal structure and grain orientation of ZnO films were determined by X-ray diffraction. SEM investigations revealed that the surface morphology of growing ZnO films on boro-silicate substrate is dominated by the smooth surface with a fine microstructure.

Reactive sputtering preparation of CuInS 2 thin films and their optical and electrical characteristics

In this paper a preparation method for CuInS 2 films by reactive sputtering together with vacuum rapid annealing was presented, and the surface morphology, microstructure, composition and photo-electrical characteristics of the CuInS 2 films were investigated. X-ray diffraction (XRD) analyses revealed that the annealed samples are CuInS 2 with the single chalcopyrite phase and a preferential crystalline orientation along (112). The free-void and compact film with the grain size of about 200 nm, as shown by scanning electron microscopy and stylus profiler (α-step) measurements, has been obtained by optimizing the processing parameters. The samples were also characterized by energy dispersive X-ray analysis, showing the constituent ratio [Cu + In]/[S] and [Cu]/[Cu + In] of about 1 and 0.5, respectively. All CuInS 2 films have a good homogeneity in shape and size of the grains and in distribution of constituent and defects as revealed by fourier transform infrared spectrometer analysis. The experiment indicated that the reactive sputtering together with vacuum rapid annealing treatment is beneficial to promote genuine realization of the large-scale production of the ultra-high efficiency Cu-III-VI2 thin film solar cells.

Effect of temperature on the Hurst and growth exponents of CdTe polycrystalline films

We have studied the influence of substrate temperature on the Hurst and growth exponents of CdTe thin films grown on glass substrates covered by fluorine doped tin oxide. The sample roughness profile was measured with a stylus profiler at different growth times and substrate temperatures in order to determine the critical exponents. The Hurst exponent increases linearly from 0.72 to 0.8, whereas the growth exponent increases exponentially from 0.14 to 0.62, for temperatures between 150 and 300°C. The global roughness also increases with growth temperature, which turns to be a very good parameter for roughness control.

Surface Roughness of Denture Base Acrylic Resins After Processing and After Polishing

Circumstances exist in which the need to adjust denture base acrylic resins is necessary. This process obviously alters the surface of the polished denture base. The purpose of this study was to compare the effects of three chairside polishing kits and conventional polishing on four denture acrylic resins. Twenty-four 30 x 30 x 2 mm acrylic resin specimens were fabricated with each of four acrylic resins: autopolymerizing, heat processed, injection molded, and microwaveable. One side was polished conventionally with pumice and polishing compound. The other side was polished with one of three chairside polishing kits: Axis, Brasseler, and Shofu. Each side was evaluated by a Dektak 8 Programmable Stylus Profiler to determine the surface roughness (Ra). One-way analysis of variance (ANOVA) revealed that: (1) There was no significant difference in the time it took to polish the specimens with the chairside polishing kits (F=2.118, p=0.14). (2) There was a significant difference in surface roughness between the acrylic resins before any polishing, with the injection-molded and heat-processed being less rough than the autopolymerizing (F=4.588, p=0.005). (3) There was a significant difference in surface roughness between the acrylic resins when conventionally polished, with the injection-molded and microwavable being less rough than the autopolymerizing (F=4.503, p=0.005). Factorial ANOVA revealed that: (1) There was no significant difference in the surface roughness among the chairside polishing kits (F=1.209, p=0.30). (2) There was a significant difference between the acrylic resins, with the heat-processed, injection-molded, and microwaveable being significantly less rough than the autopolymerizing (F=6.610, p=0.0001). (3) There was no significant interaction between the acrylic resins and the chairside polishing kit in the amount of surface roughness (F=1.728, p=0.12). An independent t-test revealed that conventional polishing was significantly smoother than polishing with the chairside polishing kits (t=3.847, p=0.0001). It was concluded that time was not a factor in using any of the chairside polishing kits. It is recommended that conventional polishing be used after adjustments to the cameo surface of denture acrylic resin.

Measuring dental wear equilibriums—the use of industrial surface texture parameters to infer the diets of fossil mammals

Inferring the diet of fossil mammals is a major approach to mammalian palaeobiology and palaeoecology. Dental wear provides a unique record of oral behaviour, available for most extant and fossil mammals. Dental wear facets are thus one of the immediate habitat interfaces allowing analysis of food selection, food availability, and dietary segregation in fossil and extant communities based on the same source of information. As any surface, wear facets can be described as a complex landscape with more or less elevated alterations. In order to describe technical surfaces, a system of surface roughness parameters is available, which are highly indicative statistical tools in characterizing surface micro texture in industrial applications. We test the hypothesis, that dental microwear can be described by established surface roughness parameters, and that these parameters can help to identify the dietary traits of fossil herbivores. We investigated three extant African bovid species, the greater kudu, the bushbuck and the hartebeest, which were selected because each of them represents one of the major dietary classes as browsers, mixed feeders and grazers, respectively. As a fossil species we investigated the upper Miocene hipparionine horse Hippotherium primigenium from the upper MN9 Dinotheriensande. A diamond stylus profiling instrument was used to measure surface roughness on four phase I shearing facets of upper molars. Discriminant analyses were performed to test 24 roughness parameters for their ability to predict dietary classes. Several parameters were identified as confidently separating the grazer and the browser in this comparison, while the mixed feeder is intermediate. For H. primigenium, we find a mixed feeding signal confirming earlier dietary reconstructions of the species based on mesowear and microwear. The degree of attrition in browsers is reflected by a high bearing ratio (RTp). In grazers, the lower bearing ratio reflects the striated and elevated topography of an abrasion dominated surface. The bearing ratio may be understood as immediately reflecting the position of the attrition–abrasion equilibrium, and thus bridging the two major methods of tooth based dietary evaluation, the microwear- and the mesowear method. Surface texture parameters are found to encapsulate information about basic dental function that we hypothesize has fundamentally driven dental adaptation in mammalian evolution.

Chattering detection in cylindrical grinding processes using the wavelet transform

This paper presents a technique for chattering detection on ground cylindrical parts. Chattering is a defect caused by vibration during the grinding process and is best described as waviness in the surface of a workpiece. In this work, such waviness is measured with a mechanical stylus profiler featuring a diamond tip, and then converted into height values with the help of a precision displacement transducer. The output signal is later converted to digital form and transformed to the time–frequency domain by means of the wavelet transform, allowing its coefficients to grow as a function of surface defects and highlighting chatter marks. The method was validated experimentally with actual production parts and it was found to adequately measure the amplitude and to give location information of the chatter marks on the analyzed surface. Results show that this method can be used objectively to identify and quantify surface quality and that it is feasible to effectively integrate it into production processes for manufacturing control.

Effect of femtosecond laser irradiation on structure of UV grade fused silica

A p-polarized femtosecond laser beam was used to irradiate a UV grade fused silica to create microchannels, which are useful for producing optical gratings or micro fluidics devices. The laser irradiated surface was characterized using optical microscope, stylus profiler, SEM, XRD and TEM. A special technique was used to protect the laser irradiated surfaces in preparing cross-sectional TEM samples. The XRD spectra and TEM observation reveal that structure of the fused silica remain amorphous after the femtosecond laser irradiation.

Development of an optical stylus displacement sensor for surface profiling instruments

The main cause of irrational results from measurements made with optical stylus instruments is speckle noise in the reflected light. To reduce or eliminate speckle noise, we developed a new optical stylus profiling system consisting of a displacement measuring part using a knife-edge and a speckle noise measurement part. Using this new system, we measured profiles of machined materials. The results show that the new system can eliminate speckle noise and can achieve a level of measurement accuracy as high as that of a contact stylus instrument.

High sensitivity polyacrylic acid films for ammonia detection with field effect devices

Thin polyacrylic acid (PAA) films, with defined geometry, have been produced by spray deposition from dilute polymer solutions on metal plated wafers. The layer morphology was characterized by standard methods: optical, atomic force and scanning electron microscopy; stylus and optical profiler. Their sensing properties toward ammonia as target gas and the related cross sensitivities towards the most relevant interferents have been determined by the Kelvin Probe (KP) technique. The influence of the deposition parameters, layer thickness, operating temperature and aging were also investigated. The study was made in order to investigate the potential of PAA as sensing material for room temperature field effect gas sensors.

Feature characterization of microfabricated microfluidic chips by PDMS replication and CCD imaging

This paper presents a new approach for the metrological characterization of microfabricated features on microfluidic chips, based on a combination of poly(dimethylsiloxane) (PDMS) replication and charge-coupled device (CCD) imaging. A PDMS replicate was cast from the original chip sample, and a 2-mm thick sample slice was cut from the replica at the cross-section to be studied. The digital image of the revealed structural profile was captured by a CCD camera under a microscope, and the image was processed using specially-developed algorithms for CCD image calibration and edge detection. Depth and width measurements obtained using the method agreed well with those gained using a stylus profiler and universal measuring microscope, with a deviation of below 0.9 mum, while profile distortions of deeper structures using stylus profilers were avoided. The method is reliable, non-destructive, and cheap and simple to implement in any analytical laboratory.

Characterization of electrodeposited metal coatings by secondary ion mass spectrometry

This paper reports the results of the elemental identification and depth profiling by secondary ion mass spectrometry (SIMS) of electroplated Ru, Pd and Au coatings on a brass substrate precoated with a nickel layer. The measurements were performed by a low-cost, custom-built instrument based on standard commercial components. The secondary ion species were identified using DECO computer code. X-ray photoelectron spectroscopy (XPS) was applied for complementary surface elemental analysis of the samples. The sputter-produced crater was measured by a stylus profiler, and the nondestructive estimation of the nickel underlayer thickness was carried out by energy dispersive X-ray fluorescence analysis (EDXRFA). It is shown that thickness of the Ru film is ca. 2.6 μm, and for the Pd and Au coatings its number lies within the range of 0.4–0.5 μm. The experimental data indicate that the Ru film contains only a few percents of nickel, and the Ru–Ni interface, in contrast with the Pd–Ni and Au–Ni interlayer boundaries, appears to be sharp due to low mutual solubility in the Ni–Ru system. On the contrary, the Pd coating can be considered as a Ni–Pd alloy with Ni concentration amounting up to 90 at.% by the SIMS and XPS estimation. The appreciable content of Ni (ca. 35–40 at.%) is revealed on the surface of the Au film by XPS. For the Ru coating, the thickness of the Ni underlayer estimated by EDXRFA is 12.2 μm; the evaluated thickness of the Ni substrate for the Pd and Au coatings is about 4.5 μm and less than 1 μm, respectively, and it can be taken only as “apparent” values because of formation of solid solutions in these systems.

Roughness of CdTe thin films grown on glass by hot wall epitaxy

Cadmium telluride films were grown on glass substrates using the hot wall epitaxy(HWE) technique. The samples were polycrystalline with a preferential (111)orientation. Scanning electron micrographs reveal a grain size between 0.1 and0.5 µm. The surface morphology of the samples was studied by measuring the roughnessprofile using a stylus profiler. The roughness as a function of growth time andscale size were investigated to determine the growth and roughness exponents,β and α, respectively. From the results we can conclude that the growthsurface has a self-affine character with a roughness exponentα equalto 0.69 ± 0.03 and almost independent of growth time. The growth exponentβ wasequal to 0.38 ± 0.06. These values agree with that determined previously for CdTe(111) films grown onGaAs(100).

Selective silver seeding on laser modified polyimide for electroless copper plating

Copper was selectively deposited on PI surface catalyzed by laser-induced deposition of Ag particles. First, PI film was ablated by a focused Nd:YAG laser ( λ = 266 nm) for patterning, and then the ablated film was immersed in a silver diammine solution. Ag(NH 3) 2 + ions were reduced to Ag at the ablated region on the film, and the Ag particles were deposited in situ. After rinsing the film, copper was deposited on the seeded film by electroless plating successfully. Deposits and the ablated film were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Stylus Profiler.

Measurement of micro-roughness using a metrological large range scanning force microscope

A new method for traceable measurement of micro-roughness by using a newly developed metrological large range scanning force microscope (LR-SFM) is described. The LR-SFM has an Abbe error free design and direct interferometric position measurement capability, and is capable of measuring samples in a volume of 25 mm × 25 mm × 5 mm along x, y and z axes. The instrumentation and several important design concepts are introduced in this paper. Measurement results of a plane glass and a micro-roughness standard have illustrated that the instrument has a low noise level of Ra = 0.58 nm and good measurement repeatability. Furthermore, a group of comparison measurements on a micro-roughness standard have been carried out between the LR-SFM and a stylus profiler. The obtained roughness values from both instruments are in excellent agreement with each other. This LR-SFM overcomes the difficulty that roughness values measured by conventional SFMs cannot be compared to stylus profilers or interference microscopes, mainly due to the fact that conventional SFMs do not have the required scanning range of ISO standardized evaluation methods.

Chemical beam epitaxial growth of AlInAs and investigations of electrolytes for ECV profiling

ALInAs has been grown by CBE technique for ultra-fast switching device applications. The materials were grown in the temperature range of 693–803 K and a low growth rate of 0.3 μm/h was employed in order to enhance the surface ad-atom residence time. The grown materials have excellent crystallographic and optical properties as studied by HRXRD and low temperature photoluminescence (LT PL) measurements. There is no suitable electrolyte available to successfully profile the dopants in AlInAs by ECV method. An effort has been made to develop an appropriate electrolyte for profiling AlInAs material. A number of electrolytic solutions were investigated and among the probed solutions, two different electrolytes namely HNO 3:H 2O 2::HF:H 2O and NH 4F have been realised. Both have very low electrolytic resistance and a low free chemical etch rate values with good I– V and C– V characteristics. Using these electrolytes, the estimated carrier concentration value were in very good agreement with independently measured HALL effect measurement values. But the ECV measured thickness value does not agree well with that of stylus profiler measurement thickness value. This discrepancy has been explained on the basis of etching properties of aluminium containing compounds during electrochemical etching process.