Voltage contrast in integrated circuits with 100 nm spatial resolution by scanning force microscopy

Böhm, Christoph; Saurenbach, F.; Taschner, Patrick A.; Roths, C.; Kubalek, E.

doi:10.1088/0022-3727/26/10/041

Cited by 51 publications

(14 citation statements)

References 8 publications

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“…Variations of flexion of the cantilever holding the tip during a scan allow us to construct an electrical image [6] on inhomogeneous materials as well as on nanostructures (superlattices, nanoelectronics, etc.) [7][8][9]. In the simple case where the tip is in front of a conductive plane sample, we can deduce the force applied on the sensor by means of analytical expressions [10][11][12] or an equivalent charge model [13].…”

Section: Introductionmentioning

confidence: 99%

Finite element simulations of the resolution in electrostatic force microscopy

Belaidi

Lebon²,

Girard

et al. 1998

Applied Physics A: Materials Science & Processing

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In this paper, we present simulation results for the electrostatic force between two conducting parts placed at different voltages: an atomic force microscope (AFM) sensor and a metallic sample. The sensor is composed of a cantilever supporting a conical tip terminated by a spherical apex. The simulations are based on the finite element method. For tip-sample distances (5-50 nm) and for an electrically homogeneous plane, the electrostatic force can be compared to the results obtained with the equivalent charge model and experiment. By scanning a plane with a potential step, the variation of the electrostatic force near the discontinuity gives the spatial resolution in electrostatic force microscopy (EFM). We establish then the relationships between the resolution, tipsample distance, and tip apex radius.The electrostatic force microscope results from one of many specializations of tip sensor in near-field microscopy [1, 2]. More precisely, this type of microscope is realized by applying a voltage on a conducting AFM tip. It is a good tool for imaging samples that present a gradient of electrical properties [3][4][5]. Variations of flexion of the cantilever holding the tip during a scan allow us to construct an electrical image [6] on inhomogeneous materials as well as on nanostructures (superlattices, nanoelectronics, etc.) [7][8][9]. In the simple case where the tip is in front of a conductive plane sample, we can deduce the force applied on the sensor by means of analytical expressions [10][11][12] or an equivalent charge model [13]. As soon as the geometry of the sample becomes complex (integrated circuits, dielectrics), the theoretical behavior of the system can be obtained by numerical methods such as the surface charge method [14], finite difference method [15], or finite element method [16].To determine the properties of the electrostatic force microscope in front of a sample with areas at different potentials, we propose to use the finite element method. In Sect. 1 we verify the results obtained by this numerical method in the simple case of a tip in front of a plane sample at constant potential [13]. In Sect. 2 we consider the response of the microscope near a potential step [17]. For this, we study the 3-dimensional tip-object system and determine the force applied on the tip by the finite element method and then we deduce the resolution for a potential step. Mathematical model The electrostatic problemThe problem consists in determining the interaction between an AFM sensor (tip + cantilever) and an infinite plane (both conducting). If the tip is long enough or the distance d between the tip and the sample is small, we can neglect the effect of the cantilever [18]. Then, the study is reduced to the calculation of the force exerted on a conical tip in front of a metallic plane. We treat the problem in 3-dimensional space because heterogeneities, as introduced in Sect. 2, cause the revolution symmetry to disappear. First, we must obtain the potential distribution in the space between the tip and the plan...

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Section: Introductionmentioning

confidence: 99%

Finite element simulations of the resolution in electrostatic force microscopy

Belaidi

Lebon²,

Girard

et al. 1998

Applied Physics A: Materials Science & Processing

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“…Recently, a pulse width modulation technique was developed, 212 which enhances measurement resolution, enabling 2D voltage maps to be presented. Böhm et al [213][214][215][216][217][218][219][220] presented a system in 1994 214 which was able to resolve signals up to 15 GHz. Leyk et al 215 presented measurements up to 104 GHz, aided by NLTLs.…”

Section: High-frequency Electrostatic Force Microscopymentioning

confidence: 99%

High-frequency near-field microscopy

Rosner

Weide

2002

Review of Scientific Instruments

219

133

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Conventional optics in the radio frequency ͑rf͒ through far-infrared ͑FIR͒ regime cannot resolve microscopic features since resolution in the far field is limited by wavelength. With the advent of near-field microscopy, rf and FIR microscopy have gained more attention because of their many applications including material characterization and integrated circuit testing. We provide a brief historical review of how near-field microscopy has developed, including a review of visible and infrared near-field microscopy in the context of our main theme, the principles and applications of near-field microscopy using millimeter to micrometer electromagnetic waves. We discuss and compare aspects of the remarkably wide range of different near-field techniques, which range from scattering type to aperture to waveguide structures.

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“…The HFSEFM technique invented by Bloom and Kubalek [18][19][20][21] has proven to be the most versatile one up to now. The potential distribution of the device under test (DUT) is monitored via the Coulomb force between the biased tip and the DUT in the dynamic mode.…”

Section: Probes For Hfsefmmentioning

confidence: 99%

Novel probes for scanning probe microscopy

Oesterschulze¹

1998

Applied Physics A: Materials Science & Processing

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Cantilever probes for scanning probe microscopy (SPM) applications are fabricated in almost any case from (100) silicon wafers. Although the probes show excellent mechanical properties which make silicon cantilevers appropriate for topography imaging by scanning force microscopy (SFM), modern SPM applications force the search for novel materials with specific material properties which would be of advantage in SPM. In this paper several concepts for SPM probes are described which make use of specific properties of gallium arsenide, diamond and various metals. Different sensor concepts, e.g. in the tip integrated Schottky diode, coplanar waveguide lines integrated on a cantilever probe, etc., are introduced. They are designed for imaging of thermal, electrical, and optical sample surface properties exploiting the unique properties of the above-mentioned materials.Since the invention of scanning force microscopy (SFM) by Binnig et al. in 1986 [1], scanning probe microscopy (SPM) has been demonstrated to be a intriguing tool for highresolution imaging of various physical surface properties [2]. In particular, the cantilever probe concept introduced for SFM has proven to be the most versatile and flexible one available so far. A prerequisite for SFM is the fabrication of probes with reproducible properties, e.g. resonance frequency, force constant, tip shape, and radius of curvature of the tip [3]. Until today the material used for probe fabrication has been almost exclusively (100)-oriented Si (or silicon nitride) because of the well-established micromachining techniques known from semiconductor technology.The most important aspect regarding the potential of SPM is the possibility to integrate various sensors in a single probe. This allows us to image additional physical quantities besides the surface topography. To achieve this aim, novel probe concepts have to be developed and realized by reproducible technological processes. Although the mechanical properties of silicon are quiet excellent with respect to SFM, in modern applications of SPM other probe properties, e.g. electrical, thermal, optical, magnetic, etc., are decisive. For this reason novel materials with specific physical properties have to be considered to optimize probe sensitivity as well as to find new applications.In the first section of the paper it is demonstrated that not only Si, but also GaAs, diamond, and thin metal filmsmaterials with unique physical properties -are appropriate materials. Technological processes will be described which allow batch processing of these materials for probe fabrication. In the second part of the paper the material properties are considered -a significant point for the development of novel active and passive SPM probes.We report on the design and micromachined fabrication of near-field probes for high-frequency scanning electrical force microscopy (HFSEFM), scanning thermal microscopy (SThM), and scanning near-field optical microscopy (SNOM). Probe concepts and fabrication processes presented include the possibilit...

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Voltage contrast in integrated circuits with 100 nm spatial resolution by scanning force microscopy

Cited by 51 publications

References 8 publications

Finite element simulations of the resolution in electrostatic force microscopy

Finite element simulations of the resolution in electrostatic force microscopy

High-frequency near-field microscopy

Novel probes for scanning probe microscopy

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