Thin films thickness measurement

Figure 1. Schematic depiction of laser beam deflection technique used for the thin-film thickness measurement experiments.

Konnerth and F.H. DiU, 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 film thickness measurement tool, Solid State Electron. 15, 371 (1972). 

A. Piegari, E. Masetti, Thin Film Thickness Measurement A Comparison of Various Techniques, Thin Solid Films 124 (1985) 249. 

K. C. Mittal, ed., Mdhesion Measurements of Thin Films, Thick Films and Bulk Coatings, ASTM STP, Philadelphia, Pa., 1978, p. 640. 

Experiments of propane pyrolysis were carried out using a thin tubular CVD reactor as shown in Fig. 1 [4]. The inner diameter and heating length of the tube were 4.8 mm and 30 cm, respectively. Temperature was around 1000°C. Propane pressure was 0.1-6.7 kPa. Total pressure was 6.7 kPa. Helium was used as carrier gas. The product gas was analyzed by gas chromatography and the carbon deposition rate was calculated from the film thickness measured by electron microscopy. The effects of the residence time and the temperature... 

The effect of wind velocity on (a) thin-film thickness and (b) piston velocity. The solid line represents results obtained from measurements made in wind tunnels. In situ measurements were made from distributions of the naturally occurring radioisotopes of carbon and radon. Source From (a) Broecker, W. S., and T.-H. Peng (1982). Tracers in the Sea. Lamont-Doherty Geological Observatory, p. 128, and (b) Bigg, G. R. (1996). The Oceans and Climate. Cambridge University Press, p. 85. 

The thickness of thin film layers separated by uniform, parallel interfaces can be determined from optical interference patterns that result. These measurements can be made from about 400 nm out through the visible spectrum and on into the near-infrared (NIR) region. Since film thickness measurements rely not on the absolnte magnitude of the reflected light, but on the variation of that signal with wavelength, the choice of nnits is less important. Typically %R is used, but in some cases raw intensity is also satisfactory. We will treat thickness determinations in more detail in the applications section of this chapter. 

Good, R. J. In Adhesion measurement of thin films, thick films and bulk coatings. K. L. Mittal, (ed.) ASTMSTP 640, ASTM, Philadelphia, PA., 1978, p. 41... 

Figure 9. A schematic diagram of the interferometer used to measure thin film thickness. The inset shows that light is both transmitted and reflected by the thin film. Reproduced from reference [7] with the permission of the Royal Society of Chemistry.

Because, as stated above, alpha particles are so easily absorbed by matter, their main uses in radiogauging have been to measure very thin film thickness and gas density, temp and pressure. Alpha particles lose their energy in matter primarily by ionization. The range of alpha particles in air, as a function of energy, can be estimated from the empirical expression (Ref 8) ... 

There are a number of subtle effects that have to be considered when making thin film stress measurements on silicon wafers First of all, the crystal orientation of the wafer Influences the resulting stress. The same thermal CVD silicon dioxide film thickness on the same substrate indicates larger tensile stresses on (100)-oriented wafers as compared with (111 (-oriented wafers. 

Even if some polymers might be hydrophobic in the bulk, concerns about possible water adsorption effects in thin films are justified, because of the preponderant role of the interface in confinement. For example, negligible water adsorption is reported in the handbook of polymers for polystyrene in the bulk 0.05% at 23 °C and 50% relative humidity. In spite of this, strong water adsorption-desorption effects were observed in thin polystyrene films the dielectric loss decreased with more than one decade when a thin film was measured in a dry nitrogen atmosphere and after 2 horns of annealing at 135 °C (Fig. 9, example for a film thickness of 223 nm). A pronounced decrease of s ( 20% at 1 Hz) was detected as well. 

Thickness and, correspondingly, capacitance variation was less than 2%. The absence of impurity peaks in XPS spectra of silica-coated specimens clearly demonstrates the achieved purity. Yield, defined as the percentage of functioning vs. total measured capacitors, was 100%. Breakdown field strength was in the range 1.1-5.4 MV/cm and leakage current was about lO -lO A/cm at 0.5 MV/cm. Capacitance density was 23-350 nF/cm dependent on thin film thickness and materials. No breakdown was observed after 20 cycles between 0-40 V. Time dependent dielectric breakdown (TDDB) was 185 s at 40 V for ten of the patterned capacitors. 

Table 1. Comparison of the thin films thickness values as measured by use of different techniques...

Thermal-Wave Measurement of Thin-Film Thickness... 

Here we shall discuss some of the results that we have obtained with this technique for the measurement of thin film thickness. 

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