Surface profilometry

Figure 4 shows the application (6) of potentials to the Pt and Au electrodes of the sandwich (vs. a reference electrode elsewhere in the contacting electrolyte solution) so that they span the E° of the poly-[Co(II/I)TPP] couple (Fig. 4B). There is a consequent redistribution of the concentrations of the sites in the two oxidation states to achieve the steady state linear gradients shown in the inset. Figure 4C represents surface profilometry of a different film sample in order to determine the film thickness from that the actual porphyrin site concentration (0.85M). The flow of self exchange-supported current is experimentally parameterized by applying Fick s first law to the concentration-distance diagram in Fig. 4B ...

Fig. 4. Voltammograms in 0.1M Eti+NClOi+ZCH CNj rT = 1.2X1 O 8 mol/cm. Curve As Cyclic voltammetry of Pt/poly-Co -NI TPP at 20 mv/s = 200pA/cm. Curve B Four-electrode voltammetry of Pt/poly-Co( -NHi(,)TPP/Au sandwich electrode with E u = 0.0 Vj Ep scanned negatively at 5 mV/s = 400pA/cm. Curve Ci Surface profilometry of a poly-Co(o-NH2)TPP film on Sn02/glassj Tt = 7.6X10 9 mol/cm. (Reproduced from Ref. 6. Copyright 1987 American Chemical Society.)...

At elevated temperature, graphite can be abrasive rather than lubricating, due to desorption of moisture, unless additives (such as dibasic ammonium phosphate) are incorporated. This abrasiveness appears to be more severe in the case of a silicon nitride counterface. Surface profilometry of the silicon nitride disks in the region of contact showed that the ceramics had been polished and, in some cases, grooves had been worn in the ceramic surfaces. 

Surface profilometry showing the height of the PEG hydrogel micropatterns. Surface profilometry across two walls of the PEG patterns showing height of 7//m and width of lOyum. 

Figure 8. Laser surface profilometry scan. The gage section profile of a precision ground and lapped tensile specimen shows that relatively large valleys persist.

Measurements of the aater depth via some form of surface profilometry... 

Surface profilometry along with sputter rate/yield equations can be thought of as ex-situ methods as these are not routinely applied during depth profiling. The term not routinely is used as there have been attempts to implement surface profilometry, in the form of interferometry within SIMS instruments for providing real time data. Although this has met with some success, design constraints and limitations to specific matrices have not resulted in its wide spread use. Ex-situ methods are discussed further in Section 5.4.1.1. 

The sputter rate (in units of A/nA.s or nm/nA.s) is then defined by dividing the crater depth (in units A or nanometer), by the sum of the sputter time (in units of seconds) and the primary ion current used in forming the respective crater (in units of nanoampere). This definition assumes a uniform sputter rate over the region (depth) sputtered, hence is only applicable to a specific matrix type. Such measurements should be carried out for each crater to ensure utmost in precision (averaging procedures are often employed to reduce statistical scatter). In the case of multilayered structures, surface profilometry measurements should be carried out once each subsequent layer is sputtered, such that sputter rates pertaining to each of the different layers can be de-convoluted (recall from Section 3.2.2 that sputter rates are dependent on many parameters including those defining the matrix). 

Although providing superior data to that of surface profilometry (three-dimensional maps are readily provided as opposed to line scans), difficulties can be... 

Laser-based profilometry is now being applied to a wide variety of both NDT and Quality Control gauging applications. In the world of NDT, the primary interest is in the details associated with surface topography or deformation of a particular component. Laser-based profilometry systems are commonly used to inspect surfaces for defects such as pitting, corrosion, deformation and cracking. Quality control gauges are used for absolute measurement of dimensions, such as the diameter and thickness of a given part. 

One of the earliest NDT applications for laser-based profilometry systems was for the inspection of marine boiler tubes. Under funding from the U.S. Navy", several systems were developed that were capable of rapidly and accurately mapping the inside surface of 25 mm and 50 mm diameter boiler tubing. Features such as internal pitting and corrosion can be located and quantitatively assessed using computer-graphic analysis. The system employs an... 

As described previously, laser-based profilometry uses a reflected signal to map a surface. In... 

Laser-based profilometry systems have also been adapted for unique applications in nuclear power generating plants. Applications where quantitative information with regard to surface condition for mechanisms such as surface pitting and flow-assisted corrosion are candidates for this NDT method. 

Another application of laser-based profilometry is the inspection of rocket and missile components. The U.S. Air Force has funded work to develop a non-contact laser-based profilometer for the inside surface of solid rocket motors. Over time, these devices are subject to slumping and cracking, which could potentially render the rocket motor ineffective and hazardous. When fully implemented, this system will provide a meaningful screening method for evaluating the condition of aging rocket motors. 

Other examples of government and military applications of laser-based profilometry include the evaluation of rocket thruster nozzles to locate and measure flame erosion remote inspection of hypervelocity test track and the measurement of sludge deposits on tube internal surfaces. 

Profilometry of softer materials, such as polymers, is also possible with SFM, and with STM if the sample is conducting. Low forces on the SFM tip allow imaging of materials whose surfaces are degraded by traditional stylus profilometry. However, when the surface is soft enough that it deforms under pressure from the SFM tip, resolution will be degraded and topography may not be representative of the true... 

Scanning probe microscopy is a forefront technology that is well established for research in surface physics. STM and SFM are now emerging ftom university laboratories and gaining acceptance in several industrial markets. For topographic analysis and profilometry, the resolution and three-dimensional nature of the data is... 

During the course of the experiment, pad surface roughness was measured by contact profilometry. Removal rate was found to be directly proportional to pad roughness (Fig. 11). Microscopic examination of the pad surface clearly showed the progressive smoothing away of the upper pad asperities (Figs. 12a-12d). No evidence of shear deformation of the asperities was... 

Stylus profilometry is a very simple and powerful tool in CMP. Profilometry can be used to determine the surface planarity change before and after CMP. Basically, in this technique, a stylus scans across a pattern feature in contact with a wafer, while the Z motion (height) of the stylus is monitored. This Z motion signal reflects the surface topography scanned. 

AFM is an advanced tool that is ideal for examination of microscopic surface topography. The main advantages of AFM over profilometry are its... 

Fig. 18. Illustration showing how the surface topography obtained using profilometry is affected by the trench size and stylus shapes. As the trench size decreases to as small as a few microns, the scan may be confounded by surface roughness.

AFM can be run in three different modes contact, noncontact, and tapping mode. When AFM is in the contact mode (similar to stylus profilometry), the most common problem encountered is that under ambient conditions, sample surfaces are covered by a layer of adsorbed gases consisting primarily of water vapor and nitrogen. In addition, a dielectric film can trap electrostatic charge, which can contribute to additional attractive forces between probe and sample. These problems may cause friction in probing, which will destroy the sample or distort the resulting data. 

Fig. 7.2. Images of GECE obtained by using SEM (left accelerated voltage, 10 kV, and resolution, 100 pm, were used) and white light interferometric profilometry (right at 50 x magnification). The surfaces have been polished as explained in the text (see Procedure 7).

Another possible application using the hierarchical nature of the wrinkles has been discussed by Efimenko and coworkers [46], They treated a mechanically stretched PDMS sheet with UV-ozone in order to create a stiff surface layer. A detailed analysis with AFM and profilometry of the wrinkles after releasing the strain showed that the wrinkling patterns are hierarchical themselves. They observed up to five generations of different wavelengths with different periodicities. These features made so structured surfaces valuable candidates for separate colloidal particles of different sizes by acting as a micro fluidic sieve. A suspension... 

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