Surface band-bending and Fermi-level pinning in doped Si observed by Kelvin force microscopy

Arita, Makoto; Torigoe, Kazuhisa; Yamauchi, Takashi; Nagaoka, Takashi; Aiso, Toru; Yamashita, Yugo; Motooka, Teruaki

doi:10.1063/1.4870419

Cited by 23 publications

(8 citation statements)

References 21 publications

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“…To improve the yield of products integrated on the Si wafer, it is important and necessary to characterize the surface properties of the Si wafer rapidly, efficiently, and quantitatively before and after the chemical treatment during the fabrication process. Several useful but complicated tools have been proposed to estimate the surface potential; these include X-ray photoelectron spectroscopy 12 , surface photovoltage measurement 13 , 14 , and Kelvin force microscopy 15 , 16 . Methods for sensitive local surface evaluation and rapid surface property mapping are still lacking and urgently needed.…”

Section: Introductionmentioning

confidence: 99%

Rapid, noncontact, sensitive, and semiquantitative characterization of buffered hydrogen-fluoride-treated silicon wafer surfaces by terahertz emission spectroscopy

et al. 2022

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Advances in modern semiconductor integrated circuits have always demanded faster and more sensitive analytical methods on a large-scale wafer. The surface of wafers is fundamentally essential to start building circuits, and quantitative measures of the surface potential, defects, contamination, passivation quality, and uniformity are subject to inspection. The present study provides a new approach to access those by means of terahertz (THz) emission spectroscopy. Upon femtosecond laser illumination, THz radiation, which is sensitive to the surface electric fields of the wafer, is generated. Here, we systematically research the THz emission properties of silicon surfaces under different surface conditions, such as the initial surface with a native oxide layer, a fluorine-terminated surface, and a hydrogen-terminated surface. Meanwhile, a strong doping concentration dependence of the THz emission amplitude from the silicon surface has been revealed in different surface conditions, which implies a semiquantitative connection between the THz emission and the surface band bending with the surface dipoles. Laser-induced THz emission spectroscopy is a promising method for evaluating local surface properties on a wafer scale.

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Section: Introductionmentioning

confidence: 99%

Rapid, noncontact, sensitive, and semiquantitative characterization of buffered hydrogen-fluoride-treated silicon wafer surfaces by terahertz emission spectroscopy

et al. 2022

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“…KPFM is based on atomic force microscopy (AFM) [ 11–13 ]. The underlying principle of KPFM is that the contact potential difference (CPD) between the tip and the sample surface is detected from the change in the resonance frequency or amplitude of the cantilever by applying an AC bias voltage [ 7 , 14 ]. The AC bias voltage modulates the electrostatic interaction force between the tip and the sample.…”

Section: Introductionmentioning

confidence: 99%

“…According to Ref. [ 14 ], increasing the concentration of impurities in a semiconductor causes band bending near the semiconductor surface; as a result, the CPD values deviates from those expected from the bulk states. Therefore, the CPD values measured by KPFM are affected by both the surface and bulk states.…”

Section: Introductionmentioning

confidence: 99%

Study of high–low KPFM on a pn-patterned Si surface

Izumi

Naitoh

et al. 2022

Microscopy

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Comparative measurements between frequency modulation Kelvin probe force microscopy (FM-KPFM) using low frequency bias voltage and heterodyne FM-KPFM using high frequency bias voltage were performed on the surface potential measurement. A silicon substrate patterned with p- and n-type impurities was used as a quantitative sample. The multi-pass scanning method in the measurements of FM-KPFM and heterodyne FM-KPFM was used to eliminate the effect of the tip-sample distance dependence. The measured surface potentials become lower in the order of the p-type region, n-type region, and n+-type region by both FM-KPFM and heterodyne FM-KPFM, which are in good agreement with the order of the work functions of the pn-patterned Si sample. We observed the difference in the surface potentials due to the surface band bending measured by FM-KPFM and heterodyne FM-KPFM. The difference is due to the fact that the charge transfer between the surface and bulk levels may or may not respond to AC bias voltage.

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“…KPFM measures the contact potential difference, which corresponds to the work function difference, between the sample surface and the tip. So far, KPFM has been used in analyses such as of the work function of metallic samples and the surface potential of semiconductor samples [3][4][5][6]. KPFM is a member of the atomic force microscopy (AFM) family, and uses an oscillating cantilever.…”

Section: Introductionmentioning

confidence: 99%

Applying Second and Third Resonance Frequencies to Surface Potential Measurements with Kelvin Probe Force Microscopy

Honda

Itoh

2018

e-J. Surf. Sci. Nanotech.

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Frequency separation between topography and potential scans in Kelvin probe force microscopy (KPFM) was investigated. Topographic images were scanned via the first resonance frequency of the cantilever excited mechanically. Potential images were scanned via the first, second, or third resonance frequency of the cantilever excited electrostatically. Good separation of the mechanical modulation to the cantilever in AC mode and the potential modulation to the probe tip was obtained when the second or third modulation frequency was used. Higher resonance modes led to a decreased capacitive effect between the cantilever and sample, which resulted in better lateral resolution of potential measurements, mainly owing to the tip-sample capacitive effect. The shorter time scale of amplitude change in the cantilever oscillation for the higher resonance frequencies led to wellconverged potential measurements. The second and third resonance frequencies are useful for separating signals in KPFM, resulting in better lateral resolution and potential difference measurements of the sample surface.

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Surface band-bending and Fermi-level pinning in doped Si observed by Kelvin force microscopy

Cited by 23 publications

References 21 publications

Rapid, noncontact, sensitive, and semiquantitative characterization of buffered hydrogen-fluoride-treated silicon wafer surfaces by terahertz emission spectroscopy

Rapid, noncontact, sensitive, and semiquantitative characterization of buffered hydrogen-fluoride-treated silicon wafer surfaces by terahertz emission spectroscopy

Study of high–low KPFM on a pn-patterned Si surface

Applying Second and Third Resonance Frequencies to Surface Potential Measurements with Kelvin Probe Force Microscopy

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