Electrical impedance tomography applied to semiconductor wafer characterization

Abstract

A new method is described for determining the distribution of resistivity of semiconductor wafers and thin conducting films. It uses peripheral electrodes to inject small direct currents into the wafer or film and to measure the resultant potential differences, from which the distribution of resistivity is calculated. The usable area of the wafer is not degraded and, because the wafer is scanned electrically, the method is much faster than conventional methods. Results obtained on silicon wafers and conducting films are presented, which demonstrate the sensitivity and reproducibility of the method.

Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review

“…EIT is a low cost, portable, fast, noninvasive, nonionizing, and radiation free technique, and hence it is found advantageous in several fields of applications application compared to the other computed tomographic methods like X-ray CT [ 134 – 136 ], X-ray mammography [ 137 ], MRI [ 138 , 139 ], SPECT [ 140 , 141 ], PET [ 142 , 143 ], ultrasound [ 144 , 145 ], and so forth. EIT has been applied in a number of research areas such as medical imaging clinical diagnosis [ 146 – 152 ], chemical engineering [ 153 ], industrial process application [ 154 , 155 ], material engineering [ 156 ], microbiology and biotechnology [ 157 , 158 ], nondestructive testing (NDT) in manufacturing technology [ 159 ], civil engineering [ 160 ], earth science and geophysics and geoscience [ 161 ], defense fields [ 162 ], archaeology [ 163 ], oceanography [ 164 ], environmental engineering [ 165 ], and other fields of applied science, engineering and technologies [ 166 ].…”

Electrical Resistance Tomography of Conductive Thin Films

“…The diameter of the sample area was 10 mm. 7 Eight equally spaced pads were defined at the same time at sample boundary, being actually in-situ electrodes, to host measurement leads, see 4 Keithley 2410 source-meter. 5 Solaronix TEC 7.…”

“…The authors used sometimes the term "conductivity" in place of "sheet conductance" when discussing mathematical or qualitative aspects. 7 Harrison Laser Pro Mercury 12 W. Fig. 3-a and -b. Conductive silver paste was used to glue the measurement leads from the sample to the measurement setup.…”

“…In this work, we present an application of ERT to the measurement of the conductivity spatial distribution of conductive thin film samples, to map the topography of their defects, inhomogeneities, and inclusions. Up to now the only earlier similar application the authors found in literature dealt with doped silicon wafers, but they recovered equally doped profiles rather than a conductivity map [7]. The application is based on a measurement setup realised with commercial instrumentation and open-source data analysis software.…”

“…The latter allows four-wire measurement combination consistent with a given ERT protocol. As an example, thicker dots represent one possible configuration of relay switches (see circular insets for open/closed notation) connecting rows and columns of the matrix that corresponds to driving current through the sample at electrode pair (7,8) while measuring the voltage drop at electrode pair (3,4).…”