Maria Stangoni

Accuracy of scanning capacitance microscopy for the delineation of electrical junctions

In this work, we investigate the theoretical and the experimental accuracy limits of the delineation of pn junctions by scanning capacitance microscopy. We compare three different techniques basing both on experimental data and on one- and two-dimensional simulations of scanning capacitance measurements of epitaxial and shallow junctions.

Two-dimensional Dopant Profiling and Imaging of 4H Silicon Carbide Devices by Secondary Electron Potential Contrast

Recent publications reported a surprisingly intensive dopant contrast arising in Secondary Electron SEM images of Silicon Carbide devices. This work gives an insight into the physics of the contrast generation and discusses the proper experimental setup to be used for the quantitative two-dimensional delineation of bipolar and homojunctions in Silicon Carbide devices.

Ensuring the reliability of electron beam crosslinked electric cables by the optimization of the dose depth distribution with Monte Carlo simulation.

The reliability of electric cables and wires using electron beam crosslinked polymers as isolator materials strongly depends on the accuracy in predicting the dose deposited during irradiation. This paper presents the main reliability issues that can be encountered in field operation, experimental data showing the criticality of the dose parameter, and proposes the use of a built-in reliability approach based on Monte Carlo simulation to design optimum processing conditions. The main requirements and advantages of the Monte Carlo based methodology are discussed in conjunction with the limitations of the traditional heuristic calculation procedure. Finally, Monte Carlo simulation is used for the first time to point out some relevant effects that occur during processing and that can lead to severe dose estimation errors.

Fine tuning of electron beam crosslinking of electrical cables and wires by three-dimensional Monte Carlo modeling

In this paper, the validity of the dose ratio criterion to define the optimum processing conditions for electron crosslinking of electric cables and wires is investigated. The energy values obtained by different calculation procedures are correlated to the results obtained by simulation with a realistic three-dimensional Monte Carlo model in conjunction with an optimization scheme to define the best dose uniformity in the cable isolation. The study shows that the dose ratio criterion does not provide the best dose uniformity, since the optimum electron beam energy value is usually underestimated.

Assessment of the Analytical Capabilities of Scanning Capacitance and Scanning Spreading Resistance Microscopy Applied to Semiconductor Devices

Abstract In this work we compare the performance of Scanning Capacitance Microscopy and Scanning Spreading Resistance Microscopy for the characterization of doping profiles in semiconductor devices. Particular attention is devoted to parameters of paramount importance for the failure analysis and the characterization of silicon devices, like the quantitative one-dimensional profiling accuracy, the electrical junction delineation and the two-dimensional sub-micron imaging capability.

Design of optimum electron beam irradiation processes for the reliability of electric cables used in critical applications

Abstract Emerging applications like solar, automotive, railway traction, and nuclear impose to electrical cables increased performances in terms of dependability. Therefore, new tools and procedures are needed to design manufacturing processes for improved reliability and less parameter variability. This paper demonstrates the use of a dedicated simulation tool for 3D dose optimization in electron beam cross-linked cables to quantify the effect of process variability on parameters that are relevant for the product lifetime. The considered process parameters are twist angle and eccentricity of the cable.

Dopant Imaging and Profiling of Wide-Band-Gap Devices by Secondary Electron Potential Contrast

Secondary electron potential contrast in scanning electron microscopy is proposed as the method of choice for two-dimensional dopant imaging and profiling of wide-band-gap semiconductor devices, including SiC MOSFETs, SiC JFETs, quantum wells, and VCSEL lasers. After a review of the physical principles governing the signal generation, the quantitative capabilities of this technique are assessed with applications to test structures and real devices

Modeling the transfer characteristic and harmonic distortion effects in scanning capacitance microscopy measurements

In this paper we investigate the dopant quantification error introduced in scanning capacitance microscopy measurements by the nonlinearity of the capacitance-to-voltage characteristic of MOS structures. The C-V response of the measurement set up is derived by finite element simulation and the systematic error introduced by signal processing is quantified by harmonic distortion analysis. It is shown that the investigated effect can lead to a systematic overestimate of the dopant concentration ranging from a factor of 2 up to a factor of 20, depending on the experimental conditions.