Semiconductor Diagnostics, Inc.

Semilab Semiconductor Physics Laboratory Co., Ltd.

Other

University of South Florida

Semilab Sdi LLC

Semiconductor Physics Laboratory Co., Ltd.

Semiconductor Diagostics, Inc.

Jacek J Lagowski

Marshall D Wilson

Alexandre Savtchouk

Piotr Edelman

Alexander Savtchouk

Carlos Almeida

Dmitriy Marinskiy

Bret Schrayer

Lubomir L Jastrzebski

John D'Amico

Lubek Jastrzebski

Andrew M Hoff

Sung-Li Wang

Joseph Nicholas Kochey

Lin-Jung Wu

Nick Kochey

Csaba Buday

Shyh-Shin Ferng

Frank Gossett

Andrei Aleinikov

Yi-Hung Lin

Vladimir Faifer

Charles Schraver

Sheng-Shin Lin

Nick Kochev

Ferenc Korsos

Andrzej Kontkiewicz

Thye Chong Loy

György Nádudvari

Methods of characterizing semiconductor doping in a wide bandgap semiconductor sample include: measuring an initial value, V, of a surface voltage at a region of a surface of the semiconductor sample in the dark; charging the region to deep depletion in the dark by depositing a prescribed corona charge at the region; measuring the surface voltage value in the dark at the region after charging; illuminating the charged region with light of a specific photon flux, f, having a photon energy above the semiconductor bandgap sufficient to generate free minority carriers in the semiconductor sample causing photoneutralization of the corona charge; monitoring of a photoneutralization induced corona charge decay at the region vs. illumination time, t, using a noncontact time resolved measurement of surface voltage, V(t); analyzing the monitored time resolved surface voltage decay data V(t) to determine values for a parameter characteristic of a photoneutralization induced corona charge decay at the regions; and using the parameter at a specific photon flux, ϕ, to characterize the property of the semiconductor at the region based on the values of the parameter.

Semiconductor doping characterization method using photoneutralization time constant of corona surface charge

Methods of characterizing semiconductor doping in a wide bandgap semiconductor sample include: measuring an initial value, V, of a surface voltage at a region of a surface of the semiconductor sample in the dark; charging the region to deep depletion in the dark by depositing a prescribed corona charge at the region; measuring the surface voltage value in the dark at the region after charging; illuminating the charged region with light of a specific photon flux, ƒ, having a photon energy above the semiconductor bandgap sufficient to generate free minority carriers in the semiconductor sample causing photoneutralization of the corona charge; monitoring of a photoneutralization induced corona charge decay at the region vs. illumination time, t, using a noncontact time resolved measurement of surface voltage, V(t); analyzing the monitored time resolved surface voltage decay data V(t) to determine a photoneutralization time constant, τ; and using the photoneutralization time constant, τat a specific photon flux, ƒ, as a semiconductor doping index and characterizing a semiconductor doping concentration at the region based on its value.

Methods of characterizing electrical properties of a semiconductor layer structure on a wafer with topside semiconductor layers on an insulating or semi-insulating substrate, the semiconductor layer structure including a high electron mobility transistor (HEMT) heterostructure with a two-dimensional electron gas (2DEG) at a heterointerface between the semiconductor layers of the heterostructure. The methods include: (a) physically contacting the topside of the wafer within a narrow border zone at an edge of the wafer with a flexible metal cantilever electrode of a contacting device, wherein the flexible metal cantilever electrode contacts one or more of the semiconductor layers exposed at the narrow border zone so that the flexible metal cantilever electrode is in electrical contact with the 2DEG; and (b) applying corona charge bias and measuring a surface voltage of the semiconductor layers using a non-contact probe while maintaining the electrical contact with the 2DEG. The physical contacting to the topside of the wafer is noncontaminating and noninvasive to the semiconductor layers.

Topside contact device and method for characterization of high electron mobility transistor (HEMT) heterostructure on insulating and semi-insulating substrates

An example method of characterizing a semiconductor sample includes measuring an initial value, V, of a surface potential at a region of a surface of the semiconductor sample, biasing the semiconductor sample to have a target surface potential value (V) of 2V or less, and depositing a monitored amount of corona charge (&#x394;Q) on the region of the surface after adjusting the surface potential to the target value. The method also includes measuring a first value, V, of the surface potential at the region after depositing the corona charge, determining the first change of surface potential (&#x394;V=V&#x2212;V), and determining the first capacitance value C=&#x394;Q/&#x394;V, and characterizing the semiconductor sample based on V, V, &#x394;V, &#x394;Qand C.

Measuring semiconductor doping using constant surface potential corona charging

An example semiconductor wafer includes a semiconductor layer, a dielectric layer disposed on the semiconductor layer, and a layer of the metal disposed on the dielectric layer. An example method of determining an effective work function of a metal on the semiconductor wafer includes determining a surface barrier voltage of the semiconductor wafer, and determining a metal effective work function of the semiconductor wafer based, at least in part, on the surface barrier voltage.

Non-contact method to monitor and quantify effective work function of metals

Methods for fast and accurate mapping of passivation defects in a silicon wafer involve capturing of photoluminescence (PL) images while the wafer is moving, for instance, when the wafer is transported on a belt in a fabrication line. The methods can be applied to in-line diagnostics of silicon wafers in solar cell fabrication. Example embodiments include a procedure for obtaining the whole wafer images of passivation defects from a single image (map) of photoluminescence intensity, and can provide rapid feedback for process control.

Photoluminescence mapping of passivation defects for silicon photovoltaics

A method is described for accurate measuring of the excess carrier lifetime on a semiconductor sample from the carrier decay after termination of the excitation pulse imposed on the steady-state carrier excitation. The method includes determining a quality of decay parameter using progressing segments in each carrier decay; establishing an accurate lifetime measurement multiparameter domain for experimental variables whereby the quality of decay parameter falls within prescribed limits from the ideal exponential decay value of QD=1; and determining an excess carrier lifetime for the semiconductor sample based on experimental measurement conditions within the domain and the quality of decay value within the predetermined range indicative of an accurate excess carrier lifetime measurement.

Accurate measurement of excess carrier lifetime using carrier decay method

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.

Accurate measuring of long steady state minority carrier diffusion lengths

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 &#x3bc;m times 100 &#x3bc;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.

Non-contact method for acquiring charge-voltage data on miniature test areas of semiconductor product wafers

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

Determining composition of mixed dielectrics

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.

Method and system for elevated temperature measurement with probes designed for room temperature measurement

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.

Steady state method for measuring the thickness and the capacitance of ultra thin dielectric in the presence of substantial leakage current

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 &angst; with a demonstrated repeatability of a 0.03 &angst; in a series of 10 measurements. Alternatively, the rate of surface potential decay is calculated at the initial moment providing a measure of the charge dissipation on a dielectric capacitor. The capacitance of a dielectric layer is calculated from this rate.

SILC characteristics and density of GOI defects of silicon wafers with thin dielectric films (e.g. SiO ) 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.

Method for measuring stress induced leakage current and gate dielectric integrity using corona discharge

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.

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Woburn, MA, United States of America

Jacek J Lagowski