Quartz crystal microbalances

Piezoelectric quartz crystal oscillators function on the basis of the well-established relationship (Sauerbery equation) between the oscillation frequency of a quartz crystal and the mass of a thin film deposited on its surface [501]. QCM has been extensively used in measurements in vacuo and in the gas phase, which includes the studies on gas phase silylation for oxygen RIE development [443] (see 6.2) and on resist outgassing [439,502]. The QCM technique has been extended to measurements in the liquid phase including aqueous media and has found powerful utility in studies of dissolution kinetics of phenolic and other acidic resists in aqueous base [503]. 

The dissolution rates obtained by the either method are then plotted in many cases as a function of the dose in a log-log mode (Fig. 172). The slope of the steepest portion of the S-shaped curve is defined as a developer selectivity 

The use of the quartz crystal microbalance in monitoring resist dissolution rates was first reported in 1985 by W.D. Hinsberg et al. This technique is based on the equation that G. Sauerbrey developed in 1959 as a method for correlating changes in the oscillation frequency of a piezoelectric crystal with the mass 

Dammel, Diazonaphthoquinone based Resists, p. 50, SPIE Press, Bellingham, WA (1993). K.L. Konnerth and F.H. Dill, In situ measurement of dielectric thickness during etching or devel oping processes, IEEE Trans. Electron. Dev. ED-22, 453 (1975) K.L. Konnerth and F.H. Dill, IOTA, a new computer controlled thin Him thickness measurement tool, Solid State Electron. 15, 371 (1972). 

In addition to deriving the equation that now bears his name, Sauerbrey also developed a method for measuring the characteristic frequency and its changes by using the crystal as the frequency-determining component of an oscillator circuit. It should be mentioned that the Sauerbrey equation was developed for oscillation in air and only applies to rigid masses attached to the crystal. However, Kanazawa and Gordon have shown that quartz crystal microbalance measurements can be performed in liquid, in which case a viscosity-related decrease in the resonant frequency is observed  

Sauerbrey, The use of quartz crystal oscillators for weighing thin layers and for micro weighing, Z. Phys. 155, 206 222 (1959). 

Electrochemistry, in general, is a technique that lends itself to be combined with other techniques. One such technique is gravimetry. Electrogravimetry, discussed earlier in the chapter, is a technique that relies upon the application of a current or potential to deposit an electroactive species onto an electrode. After the material is deposited, its mass is determined analytically. A quartz crystal microbalance (QCM) is an instrument that monitors mass changes in real time. 

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The measurement of mass using a quartz crystal microbalance is based on the piezoelectric effect.When a piezoelectric material, such as a quartz crystal, experiences a mechanical stress, it generates an electrical potential whose magnitude is proportional to the applied stress. Gonversely, when an alternating electrical field is... 

Acoustic Wave Sensors. Another emerging physical transduction technique involves the use of acoustic waves to detect the accumulation of species in or on a chemically sensitive film. This technique originated with the use of quartz resonators excited into thickness-shear resonance to monitor vacuum deposition of metals (11). The device is operated in an oscillator configuration. Changes in resonant frequency are simply related to the areal mass density accumulated on the crystal face. These sensors, often referred to as quartz crystal microbalances (QCMs), have been coated with chemically sensitive films to produce gas and vapor detectors (12), and have been operated in solution as Hquid-phase microbalances (13). A dual QCM that has one smooth surface and one textured surface can be used to measure both the density and viscosity of many Hquids in real time (14). 

Bulk and surface imprinting strategies are straightforward tools to generate artificial antibodies. Combined with transducers such as QCM (quartz crystal microbalance), SAW (surface acoustic wave resonator), IDC (interdigital capacitor) or SPR (surface plasmon resonator) they yield powerful chemical sensors for a very broad range of analytes. 

An electrochemical quartz crystal microbalance (EQCM or QCM) can be used to estimate the surface roughness of deposited lithium [43],... 

Film-forming chemical reactions and the chemical composition of the film formed on lithium in nonaqueous aprotic liquid electrolytes are reviewed by Dominey [7], SEI formation on carbon and graphite anodes in liquid electrolytes has been reviewed by Dahn et al. [8], In addition to the evolution of new systems, new techniques have recently been adapted to the study of the electrode surface and the chemical and physical properties of the SEI. The most important of these are X-ray photoelectron spectroscopy (XPS), SEM, X-ray diffraction (XRD), Raman spectroscopy, scanning tunneling microscopy (STM), energy-dispersive X-ray spectroscopy (EDS), FTIR, NMR, EPR, calorimetry, DSC, TGA, use of quartz-crystal microbalance (QCMB) and atomic force microscopy (AFM). 

QCMB RAM SBR SEI SEM SERS SFL SHE SLI SNIFTIRS quartz crystal microbalance rechargeable alkaline manganese dioxide-zinc styrene-butadiene rubber solid electrolyte interphase scanning electron microscopy surface enhanced Raman spectroscopy sulfolane-based electrolyte standard hydrogen electrode starter-light-ignition subtractively normalized interfacial Fourier transform infrared... 

The electrochemical quartz crystal microbalance (EQCM) is a powerful tool for elucidating interfacial reactions based on the simultaneous measurement of electrochemical parameters and mass changes at electrode surfaces. The microbalance is based on a quartz crystal wafer, which is sandwiched between two electrodes, used to induce an electric field (Figure 2-20). The field produces a mechanical oscillation... 

FIGURE 2-20 The quartz crystal microbalance a, the quartz crystal b, the gold electrode c... 

Such approximation is valid when the thickness of the polymeric layer is small compared to die thickness of die crystal, and the measured frequency change is small with respect to the resonant frequency of the unloaded crystal. Mass changes up to 0.05% of die crystal mass commonly meet this approximation. In die absence of molecular specificity, EQCM cannot be used for molecular-level characterization of surfaces. Electrochemical quartz crystal microbalance devices also hold promise for the task of affinity-based chemical sensing, as they allow simultaneous measurements of both tile mass and die current. The principles and capabilities of EQCM have been reviewed (67,68). The combination of EQCM widi scanning electrochemical microscopy has also been reported recently for studying die dissolution and etching of various thin films (69). The recent development of a multichannel quartz crystal microbalance (70), based on arrays of resonators, should further enhance die scope and power of EQCM. 

EC mechanism, 34, 42, 113 E. Coli, 186 Edge effect, 129 Edge orientation, 114 Electrical communication, 178 Electrical double layer, 18, 19 Electrical wiring, 178 Electrocapillary, 22 Electrocatalysis, 121 Electrochemical quartz crystal, microbalance, 52 Electrochemihuiiinescence, 44 Electrodes, 1, 107... 

Fig. 11. Photograph of the four-electrode, vacuum flange and dual, quartz crystal, microbalance assembly, (A) side view, and (B) front view, used for mixed Cr atom. Mo atom matrix depositions with simultaneous monitoring of the individual metal flows. (The resolution of the microbalance is 10 g) (113).

Nucleic acid hybridization can be detected by means of the piezoelectric QCM (= quartz crystal microbalance) (a) Y Okahata, Y Matsunobu, K Ijiro, M Mukae, A Murakami, K Makino. J. Am. Chem. Soc. 114 8299-8300, 1992 (b) S Yamaguchi, T Shimomura. Anal. Chem. 65 1925-1927,1993 (c) KIto, KHashimoto, Y Ishimori. Anal. Chim. Acta 327 29-35,1996 ... 

Saloniemi H, Kemell M, Ritala M, Leskela M (2000) PbTe electrodeposition studied by combined electrochemical quartz crystal microbalance and cyclic voltammetry. J Electroanal Chem 482 139-148... 

Lincot D, Ortega-Borges R (1992) Chemical bath deposition of cadmium sulfide thin films. In situ growth and structural studies by Combined Quartz Crystal Microbalance and Electrochemical Impedance techniques. J Electrochem Soc 139 1880-1889... 

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