Semilab Semiconductor Physics Laboratory Co., Ltd.

Semiconductor Diagnostics, Inc.

Alexandre Savtchouk

Jacek J Lagowski

Marshall D Wilson

Carlos Almeida

Bret Schrayer

Lubomir L Jastrzebski

Dmitriy Marinskiy

Piotr Edelman

John D'Amico

Csaba Buday

Nick Kochey

Frank Gossett

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

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

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.

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Tampa, FL, United States of America

Alexandre Savtchouk