Abstract: Surface photo-voltage measurements are used to accurately determine very long steady state diffusion length of minority carriers and to determine iron contaminant concentrations and other recombination centers in very pure wafers. Disclosed methods use multiple (e.g., at least two) non-steady state surface photovoltage measurements of diffusion length done at multiple (e.g., at least two) modulation frequencies. The measured diffusion lengths are then used to obtain a steady state diffusion length with an algorithm extrapolating diffusion length to zero frequency. The iron contaminant concentration is obtained from near steady state measurement of diffusion length at elevated frequency before and after iron activation. The concentration of other recombination centers can then be determined from the steady state diffusion length and the iron concentration measured at elevated frequency.

Abstract: The surface photovoltage dopant concentration measurement of a semiconductor wafer is calibrated by biasing the semiconductor wafer into an avalanche breakdown condition in a surface depletion region; determining a contact potential difference value corresponding to an avalanche breakdown; determining small signal ac-surface photovoltage value corresponding to an avalanche breakdown; and using the values of the contact potential and the surface photovoltage to calculate a calibration constant that relates depletion layer capacitance and an inverse of the surface photovoltage.

Abstract: A non-contact method is described for acquiring the accurate charge-voltage data on miniature test sites of semiconductor wafer wherein the test sites are smaller than 100 ?m times 100 ?m. The method includes recognizing the designated test site, properly aligning it, depositing a prescribed dose of ionic charge on the surface of the test site, and precise measuring of the resulting voltage change on the surface of the test site. The method further compromises measuring of the said voltage change in the dark and/or under strong illumination without interference from the laser beam employed in the Kelvin Force probe measurement of the voltage. The method enables acquiring of charge-voltage data without contacting the measured surface of the wafer and without contaminating the wafer. Thus, the measured wafer can be returned to IC fabrication line for further processing.

Abstract: Techniques for determining the composition of mixed dielectric layers are disclosed.

Abstract: Techniques for measuring a contact potential difference of a sample at an elevated temperature using a probe designed for room temperature measurement are disclosed. In such measurements, probe damage by excessive heating can be prevented without any probe modifications to include probe cooling. This can be achieved by minimizing the time the probe spends in close proximity to the heated sample. Furthermore, the effect of probe heating by the sample on the probe reading can be corrected by including an additional contact potential difference measurement of a reference plate kept at room temperature in the measurement cycle.

Abstract: A method is described for measuring the capacitance and the equivalent oxide thickness of an ultra thin dielectric layer on a silicon substrate in which the dielectric layer is uniform or patterned. The surface of a dielectric layer is electrically charged by a flux on ions from a corona discharge source until a steady state is reached when the corona flux is balanced by the leakage current across a dielectric. The flux is abruptly terminated and the surface potential of a dielectric is measured versus time. The steady state value of the surface potential is obtained by extrapolation of the potential decay curve to the initial moment of ceasing the corona flux. The thickness of a dielectric layer is determined by using the steady state potential or by using the value of the surface potential after a predetermined time.

Abstract: A method is described for non-contact measuring the capacitance and the equivalent oxide thickness of ultra thin dielectric layer on a silicon substrate. The surface of a dielectric layer is electrically charged by a flux on ions from a corona discharge source until a steady state is reached when the corona flux is balanced by the leakage current across a dielectric. The flux is abruptly terminated and the surface potential of a dielectric is measured versus time. The steady state value of the surface potential is obtained by extrapolation of the potential decay curve to the initial moment of ceasing the corona flux. The thickness of a dielectric layer is determined by using the steady state potential or by using the value of the surface potential after a predetermined time. The method produces highly accurate results for oxide thickness below 40 Å with a demonstrated repeatability of a 0.03 Å in a series of 10 measurements.

Abstract: A method and apparatus for measuring the concentration of different mobile ions in the oxide layer of a semiconductor wafer from the contact potential shift caused by different ions drifting across the oxide that includes depositing charge (e.g., using a corona discharge device) on the surface of the oxide and heating the wafer to allow different mobile ions in the oxide to drift. The difference in the contact potential measured before and after heating provides an indication of the different mobile ion concentration in the oxide layer.

Abstract: SILC characteristics and density of GOI defects of silicon wafers with thin dielectric films (e.g. SiO2) are determined using a non-contact method that does not require any test structures on the wafer. The method includes stressing a dielectric with a corona discharge and measuring the dielectric current-dielectric voltage (I-V) characteristics by monitoring under illumination the corona charge neutralization after stress. An I-V measurement done as function of corona fluence gives SILC characteristics of the wafer. The SILC characteristics are then compared at a constant dielectric field to provide a measure of GOI defect density. The I-V characteristic corresponding to low fluence that does not generate measurable SILC are used to determine a thickness of dielectric film.

Abstract: Minority carrier diffusion lengths are determined fast, accurately, and conveniently by illuminating a surface of the semiconductor with a beam composed of a plurality of light fluxes each having a different wavelength modulated at a different frequency. Surface photovoltages induced by different light fluxes are simultaneously detected by monitoring surface photovoltage signals at the different modulation frequencies. The surface photovoltage signals are frequency calibrated and then used to calculated a minority carrier diffusion length.

Abstract: The invention relates to a device for contacting and electrically grounding semiconductor substrate coated with or otherwise having an insulating film positioned thereover. The device includes a chuck having a wafer support surface which holds the wafer and a scriber movably attached to the chuck. The scriber is configured to contact the wafer through an opening in the chuck and to produce a perforation through the insulating film. The device further includes an electrically conductive probe movably attached to the chuck and configured to be moved into an access opening in the chuck to contact the semiconductor substrate through the perforation. Thus, the device increases the accuracy of open circuit type measurements of the wafer surface potential, particularly for Kelvin and Monroe electrode measurements of electrical properties of insulating films on semiconductor substrates.

Abstract: A method of determining charge associated with traps present in a semiconductor oxide interface is described. The method includes the steps of depositing a dose of charge over a surface of the oxide and measuring a resultant value of surface potential barrier at the portion of the surface. From the measured value of surface charge and deposited charge dose a value of charge associated with the interface trap is determined. The method also includes determining space charge corresponding to the measured surface potential barrier of the portion of the substrate. With the determined space charge and known deposited charge the interface trapped charge is determined by noting that the change in interface trapped charge is related to the negative of the changes in space charge and deposited charge.

Abstract: A method and apparatus for measuring the concentration of mobile ions in the oxide layer of a semiconductor wafer from the contact potential shift caused by ion drift across the oxide that includes depositing charge (e.g., using a corona discharge device) on the surface of the oxide and heating the wafer to allow mobile ions in the oxide (especially Na.sup.+) to drift. The difference in the contact potential measured before and after heating provides an indication of the mobile ion concentration in the oxide layer.