SURFACE IMPEDANCE OF SILICON SUBSTRATES AND FILMS

It is shown that at microwave-millimeterwave frequencies and for DC re sistivities below r(+) = (2pf(t)much less than(0)much less than(L))(-1 ) silicon should be regarded as a lossy metal characterized by resisti vity, skin depth, and surface impedance, while at higher resistivities it may be regarded as a lossy dielectric characterized by a lattice d ielectric constant (much less than(L) = 11.7) and loss tangent. The sh eet resistance defined as a ratio of DC resistivity to film thickness is not an adequate parameter to characterize the films at microwave fr equencies. The surface impedance of a thin semiconductor film is compl ex with both real and imaginary parts strongly dependent on frequency, DC resistivity of substrate and him, substrate thickness, and the pre sence of a ground plane on the backside of the substrate. (C) 1998 Joh n Wiley & Sons, Inc.