Beam Induced Charge Microscopy Research Articles

Study on the bias-dependent effects of proton-induced damage in CdZnTe radiation detectors using ion beam induced charge microscopy

The influence of damage induced by 2MeV protons on CdZnTe radiation detectors is investigated using ion beam induced charge (IBIC) microscopy. Charge collection efficiency (CCE) in irradiated region is found to be degraded above a fluence of 3.3×1011p/cm2 and the energy spectrum is severely deteriorated with increasing fluence. Moreover, CCE maps obtained under the applied biases from 50V to 400V suggests that local radiation damage results in significant degradation of CCE uniformity, especially under low bias, i. e., 50V and 100V. The CCE nonuniformity induced by local radiation damage, however, can be greatly improved by increasing the detector applied bias. This bias-dependent effect of 2MeV proton-induced radiation damage in CdZnTe detectors is attributed to the interaction of electron cloud and radiation-induced displacement defects.

A review of ion beam induced charge microscopy

Since its development in the early 1990’s, ion beam induced charge (IBIC) microscopy has found widespread applications in many microprobe laboratories for the analysis of microelectronic devices, dislocations, semiconductor radiation detectors, semi-insulating materials, high power transistors, charge-coupled arrays, solar cells, light emitting diodes, and in conjunction with Single Event Upset imaging. Several modalities of the techniques have been developed, such as lateral IBIC and time-resolved IBIC. The theoretical model of IBIC generation and collection has developed from a one-dimensional model of charge drift and diffusion to a detailed model of the motion of ion charge carriers in semiconductors and insulators. This paper reviews the current state-of-the-art of IBIC theory and applications.

Ion beam induced charge microscopy studies of power diodes

Ion beam induced charge microscopy (IBIC microscopy) has been established recently as ananalytical tool for the characterization of various types of semiconductor devices. In thispaper the potential of IBIC microscopy for the analysis of deeply buried structures of highpower devices under biases of more than 2 kV is discussed. Such data are useful inthe design process of high power devices because excessive fields at device edgeregions or within protection elements (e.g. field ring structures) can be avoided.Since charge collection efficiency within depleted pn junctions is typically 100% for IBIC analysis, the contrastdue to E-field variations within the large depletion regions of high power devices is limited. Here wewill introduce a new approach for enhancing this contrast by using the temporalinformation from the IBIC signals gained with a transient IBIC set-up. Simulations andexperimental data will be compared to evaluate the suitability of the new approach. Thedevice used here is a high voltage diode with a field ring structure which was analysedusing a 2 MeV proton beam.

Modeling of deep buried structures in high-power devices based on proton beam induced charge microscopy

In this paper the possible application of ion beam induced charge (IBIC)-microscopy for the analysis of the electrical field distributions within the depletion regions of high-power devices is discussed. The application of a reverse bias voltage allows one to obtain information about the field distribution within the device under working conditions from IBIC measurements. Such data are useful in the design process of high-power devices because excessive fields within protection elements (e.g. field ring structures) can be avoided. Charge collection spectra taken under reverse voltages of more than 1 kV are discussed. The results have been compared with simulations of the IBIC-processes using the code MEDICI.

Analysis of high-power devices using proton beam induced charge microscopy

Analysis of high-power devices using proton beam induced charge microscopy

IBIC analysis of high-power devices

The technique of ion beam induced charge microscopy (IBIC microscopy) has been used for several years to analyse integrated circuits, radiation detectors and solar cells [H. Schöne, D.N. Jamieson, MRS Bull. 25 (2000) 14]. In this work, results from a first attempt to investigate high-power devices with this technique are reported. It is demonstrated that IBIC analysis allows the characterisation of layers of different doping types located several tens of microns below the sample surface with an ion beam energy of 2 MeV. The devices investigated are high-power light-triggered thyristors [M. Ruff, H.-J. Schulze, U. Kellner, IEEE (ED) 46 (1999) 1768; F.-J. Niedernostheide, H.-J. Schulze, J. Dorn, U. Kellner-Werdehausen, D. Westerholt, in: Proceedings of the 12th International Symposium on Power Semiconductors and IC's, ISPSD'2000, Toulouse, France, 2000, p. 267].

Analysis of high-power devices using proton beam induced currents

Ion beam induced charge microscopy (IBIC microscopy), a new technique which utilizes a focused beam of high energy (several MeV) protons, has been used to analyse various semiconductor structures, e.g. microelectronic circuits, radiation detectors, solar cells and CVD diamond thin films [1, 2]. Here we report the first attempt to investigate high power devices with this technique. It is demonstrated that IBIC analysis allows the characterisation of layers of different doping types located several tenths of microns below the sample surface using an ion beam energy of 2 MeV. The devices investigated are high-power light-triggered thyristors.

Simulation of pulse height spectra in ion beam induced charge microscopy of polycrystalline silicon

This article describes computer simulations of the charge pulse height spectra that are obtained by irradiating selected regions of a polycrystalline silicon solar cell by a 2 MeV He+microbeam. The spectra are calculated in terms of the energy loss function of the ions and the distribution of the charge collection probability at a grain boundary, and illustrate the effect of the interface recombination velocity of the grain boundary and the bulk diffusion length. The simulations are compared with some experimental spectra to demonstrate the applicability of the theory. The method can be extended to the analysis of other semiconductor defects or more complex devices.

Recent results in ion beam induced charge microscopy: Unconnected junction contrast and an assessment of single contact IBIC

The recent development of Ion Beam Induced Charge Microscopy (IBIC) promises to deliver a powerful imaging tool for the analysis of active regions in microelectronics devices. The high penetration power (47 μm for 2 MeV protons in Si) allows direct high resolution access to buried structures, a feature not available to the well established EBIC (Electron Beam Induced Current) technique. As multi-level designs become more prevalent this deep penetration is a significant advantage. We report several results: firstly, that contrast is present in IBIC images from junctions that are not directly connected to the preamplifier. The contrast from unconnected junctions vanishes if these junctions are short circuited. Secondly, we discuss the degradation of IBIC images under prolonged irradiation for protons and He + ions. Finally, we discuss the feasibility of single connection IBIC imaging. We demonstrate that IBIC imaging is possible with only one connection to the device substrate.

Unconnected junction contrast in ion beam induced charge microscopy

A new contrast mechanism in ion beam induced charge imaging in semiconductors is reported. Junctions not directly connected to the charge collection preamplifier were found to give rise to significant charge collection signals. Imaging with these signals is carried out, thus enabling the mapping of junctions not directly connected to the charge collection amplifier.

Ion beam induced charge microscopy for the analysis of integrated circuits

Ion beam induced charge (IBIC) microscopy provides a means of imaging the depletion layers of working microelectronic devices beneath their thick metallizaion and passivation layers. The concept of IBIC microscopy is outline, its advantages over optical and electron microscopy techniques are outlined, its advantages over optical ad electron micorscopy techniques are described, and examples of images are presented. One particular application is as a way of identifying device components that are susceptible to having their logic state altered by cosmic rays when used in satellites, for example.