Electrical properties of thick film resistors from noise measurements

摘要

Thick film resistors (TFRs) are currently the only materials in microelectronic use whose conductivity can be tailored through composite mixtures of conductive phases within a glassy matrix [1,2], to span resistivities in the wide range of 10~3-103Qcm, giving sheet resistances of 1 Q/D to 1MQ/Q Although DuPont-Birox 1400-series or similar ruthenium based TFRs are widely used in modern microelectronic circuits, there is limited data on their intrinsic electrical transport properties such as the charge carrier concentration, drift mobility, etc, TFRs have generally been found to be relatively noisy in the audio frequency range and up to -TO5 Hz above which the 1/f noise becomes buried in the white noise. Although the noise characteristics of TFRs have been studied (e.g. [3, 4]), most of the results published to date have not been correlated to, or used to infer, their electrical properties such as carrier concentration, drift mobility, momentum relaxation time, etc. Given the lack of data on the latter electrical transport parameters we have there-fore tried to extract these electrical properties from the measured noise spectra and conductivity. We have measured the excess noise (or 1/f noise) in a number of well-defined TFRs made from inks of the Birox 1400 series in an effort to evaluate, at least as an order of magnitude, the free carrier concentration (nc), the drift mobility (μ), mean free path (λ) diffusion coefficient (D), Debye screening length (L), etc.