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The availability of very sharp, wear-proof, electrically conductive probes is one crucial issue for conductive atomic force microscopy (AFM) techniques such as scanning capacitance microscopy, scanning spreading resistance microscopy, and nanopotentiometry. The purpose of this systematic study is to give an overview of the existing probes and to evaluate their performance for the electrical techniques with emphasis on applications on Si at high contact forces. The suitability of the characterized probes has been demonstrated by applying conductive AFM techniques to test structures and state-of-the-art semiconductor devices. Two classes of probes were examined geometrically and electrically: Si sensors with a conductive coating and integrated pyramidal tips made of metal or diamond. Structural information about the conductive materials was obtained by electron microscopy and other analytical tools. Swift and nondestructive procedures to characterize the geometrical and electrical properties of the probes p...

We have imaged several n-type metal-oxide-semiconductor transistors with different source and drain architectures to assess the feasibility of extracting useful figures of merit, such as the effective channel length of a device, from the data. By varying the dc bias on the sample we observe a shift of the junction position in the image and consider how best to interpret a set of voltage dependent images produced for a single sample. Careful attention is paid to the effects of surface variation from sample preparation and tip wear during an experiment by considering the scanning capacitance microscopy signal in the substrate as a function of applied dc bias.

The phenomenon of contrast reversal in scanning capacitance microscopy (SCM) imaging will be discussed, taking into account the implications for samples which contain both p-type and n-type dopants. Experiments show that a monotonic change in SCM output versus dopant concentration for large dynamic range samples (1014–1020 cm−3) is dependent on the applied dc bias. Incorrect adjustment of this parameter can lead to contrast reversal in the SCM images causing a problem for conversion algorithms and dopant quantification. Simulation results demonstrating this feature will be presented. In addition, the appearance of shifting bands which are common in voltage-dependent measurements of p-n junctions complicates the data interpretation and extraction of length measurements within an image, such as the effective electrical channel length in the case of transistor characterization. The significance of these problems with respect to the SCM response curve will be discussed.

An overview of the existing two-dimensional carrier profiling tools using scanning probe microscopy includes several scanning tunneling microscopy modes, scanning capacitance microscopy, Kelvin probe microscopy, scanning spreading resistance microscopy, and dopant selective etching. The techniques are discussed and compared in terms of the sensitivity or concentration range which can be covered, the quantification possibility, and the final resolution, which is influenced by the intrinsic imaging resolution as well as by the response of the investigated property to concentration gradients and the sampling volume. From this comparison it is clear that, at present, none of the techniques fulfills all the requirements formulated by the 1997 Semiconductor Industry Association roadmap for semiconductors [National Technology Roadmap for Semiconductors (Semiconductor Industry Association, San Jose, CA, 1997)]. Most methods are limited to pn-junction delineation or provide a semiquantitative image of the differen...

Nanopotentiometry is a scanning probe microscopy (SPM) technique providing insight in the actual working behavior of semiconductor devices under operation. In nanopotentiometry, a conductive SPM tip is used as a voltage probe in order to measure the distribution of the electrical potential on the cross section of an operating device. The information thus provided is complementary to carrier profiling and is a method for the calibration of device simulations. The suitability of alternative SPM techniques for studying ultrashallow devices under operation is examined. Measurements have been carried out in deep submicron complementary metal–oxide–semiconductor devices. The impact of the changes in the doping profile on the potential distributions has been explored using simulations and experimental results. Due to further improvements in sample preparation and measurement methodology, the response of the devices to variable bias conditions could be studied in more detail. The formation of the conductive chann...

In this article the results of a numerical simulation of the thermal and mechanical properties of micromechanical sensors are described. Finite element analysis is used to model the response of the composite cantilever to temperature variations. The simulations consider triangular shaped cantilevers in air and water environments and under different configurations of thermal loading. The models utilize conditions from actual experiments which are conducted in parallel. Good agreement between numerical and experimental results studied so far allows us to use our numerical simulation to confidently predict the performance of the sensor under novel operating conditions and to optimize the sensor design for specific applications.