Quantitative two-dimensional dopant profiling of abrupt dopant profiles by cross-sectional scanning capacitance microscopy

Huang, Yu‐Ping; Williams, C. C.; Wendman, Mark A.

doi:10.1116/1.580260

Cited by 46 publications

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“…The SCM used in this study is similar to the one described previously [12][13][14][15][16][17]. Briefly, a contact-mode AFM, with the beam deflection method, was used.…”

Section: Methodsmentioning

confidence: 99%

“…The SCM was able to detect the small variations in capacitance even at highly doped regions by sensing the depletion modulation [12]. The carrier density profile at one point and the two-dimensional (2D) map at a fixed bias were measured, showing good agreement with SIMS results within the dopant range of 10 17 -10 20 cm −3 [13][14][15][16][17]. The dopant profile can be estimated by comparing the measured C-V dependence with the SIMS result.…”

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confidence: 97%

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Recombination dynamics of traps in SiO 2 layer on Si by scanning capacitance microscopy

Kang

Kim

Kuk

et al. 1998

Applied Physics A: Materials Science & Processing

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The depth-dependent carrier density and trapped charges in an arsenic-implanted silicon sample were measured by using scanning capacitance microscopy (SCM). The position-dependent capacitance versus voltage scans were measured at various dc bias voltages. A strong dc bias dependence was observed at the interface of an abrupt junction between n + and p. The bias-dependent SCM images were used to follow the recombination dynamics of traps. The results show good agreement with quasi-three-dimensional simulations, suggesting that they can be used to map device structure.With the recent developments in silicon submicrometer technology, the characterization of the three-dimensional carrier density profile in a device has become one of the most important issues. In a sub-micron device, it is very difficult to directly measure the carrier density profile around the gate because many tools measure only the profile averaged over a large area. Secondary ion mass spectrometry (SIMS) and spreading resistance profilometry (SRP) have widely been used to measure dopant profiles. The tomographic approach [1] and the angle lapping technique [2] have been developed to measure two-dimensional profiles with improved resolution. Recently, nano-SRP, utilizing scanning probe microscopy, has further improved spatial resolution [3][4][5]. Other important problems in submicron MOS devices are device failure and noise from hot electron effects and trapped charges. If the gate oxide in a MOS device becomes thinner than 10 nm and 5 V is still applied to the gate, problems related to the hot electron effect and trapped charges become more serious. At present there is no tool to measure the local defects such as trapped charges and the defects created by hot electrons. When data is taken by macroscopic measuring tools and then compared with the simulated results poor agreement is found.Since the advent of the scanning tunneling microscope (STM) and the atomic force microscope (AFM), geometrical and electrical measurements of a semiconductor surface have become possible with atomic resolution. As a probe is scanned over a specific area, the carrier density profile [6], the potential across abrupt junctions [7], the impurity distribution [8], and the carrier scattering near defect centers [9] can be measured at the same time. The carrier density of a semiconductor can be mapped by the capacitance-voltage (C-V ) dependence, and the geometrical structure can be measured by STM or AFM. In order to have good spatial resolution, the sensitivity of the detector has to be better than 10 −19 F [10]. This can be achieved with the scanning capacitance microscope (SCM) operating under ambient conditions by using a sample with only a capping oxide and without any further extensive sample preparation. However, it only measures the carrier density rather than the dopant concentration of the semiconductor surface. If the dopant density does not vary abruptly within a few Debye lengths, it can be estimated from the measured C-V dependence [11]. In an earlier SCM...

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“…The SCM used in this study is similar to the one described previously [12][13][14][15][16][17]. Briefly, a contact-mode AFM, with the beam deflection method, was used.…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 97%

Recombination dynamics of traps in SiO 2 layer on Si by scanning capacitance microscopy

Kang

Kim

Kuk

et al. 1998

Applied Physics A: Materials Science & Processing

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“…Figure 3 shows simulated data for flat and spherical tips with a 35 nm radius. The dopant profile used for this simulation was the SEMATECH # 1 SIMS data (6). The figure also shows experimental data that was obtained with an MFM tip.…”

Section: Simulation Of Data Using the Physical Modelmentioning

confidence: 99%

Inverse modeling applied to Scanning Capacitance Microscopy for improved spatial resolution and accuracy

McMurray

Williams

1998

The 1998 International Conference on Characterization and Metrology for ULSI Technology

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Scanning Capacitance Microscopy (SCM) is capable of providing two-dimensional information about dopant and carrier concentrations in semiconducting devices. This information can be used to calibrate models used in the simulation of these devices prior to manufacturing and to develop and optimize the manufacturing processes. To provide information for future generations of devices, ultra-high spatial accuracy (<10nm) will be required. One method, which potentially provides a means to obtain these goals, is inverse modeling of SCM data. Current semiconducting devices have large dopant gradients. As a consequence, the capacitance probe signal represents an average over the local dopant gradient. Conversion of the SCM signal to dopant density has previously been accomplished with a physical model which assumes that no dopant gradient exists in the sampling area of the tip. The conversion of data using this model produces results for abrupt profiles which do not have adequate resolution and accuracy. A new inverse model and iterative method has been developed to obtain higher resolution and accuracy from the same SCM data. This model has been used to simulate the capacitance signal obtained from one and two-dimensional ideal abrupt profiles. This simulated data has been input to a new iterative conversion algorithm, which has recovered the original profiles in both one and two dimensions.In addition, it is found that the shape of the tip can significantly impact resolution. Currently SCM tips are found to degrade very rapidly. Initially the apex of the tip is approximately hemispherical, but quickly becomes flat. This flat region often has a radius of about the original hemispherical radius. This change in geometry causes the silicon directly under the disk to be sampled with approximately equal weight. In contrast, a hemispherical geometry samples most strongly the silicon centered under the SCM tip and falls off quickly with distance from the tip's apex. Simulation of the expected signal for each tip geometry shows significant differences in the expected resolution. This has also been explored experimentally with the SEMATECH # 1 sample. This sample has a staircase dopant profile with 50 nm steps. Simulation of the expected signal for the SEMATECH # I using a fiat tip model shows good agreement with measured data. However, the flattened tip reduces the steps in the profile to inflections.

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“…Among them, scanning resistance microscopy, 1,2 scanning capacitance microscopy ͑SCM͒, 3,4 scanning Kelvin probe microscopy 5 and selective etching combined with transmission electron microscopy or atomic force microscopy 6,7 are promising tools for 2D high resolution carrier profiling. Recent developments in this field have focused on the quantitative carrier mapping in nanoscale very large scale integrated device cross sections.…”

Section: Introductionmentioning

confidence: 99%

“…The model needed to convert the capacitance measurement data into carrier concentration is relatively simple, and has been well established. 3,4 Importantly, the measurement is free of the problems caused by trapped charge and charge migration. This is due to the absence of any insulation layer between the metal probe and the semiconductor surface.…”

Section: Introductionmentioning

confidence: 99%

Quantitative two-dimensional carrier profiling of a 400 nm complementary metal–oxide–semiconductor device by Schottky scanning capacitance microscopy

Tran

Nxumalo

et al. 2000

Journal of Applied Physics

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Articles you may be interested inNoncontact-mode scanning capacitance force microscopy towards quantitative two-dimensional carrier profiling on semiconductor devices Appl. Phys. Lett. 90, 083101 (2007); 10.1063/1.2454728 Two-dimensional carrier profiling on operating Si metal-oxide semiconductor field-effect transistor by scanning capacitance microscopy Analysis of the two-dimensional-dopant profile in a 90 nm complementary metal-oxide-semiconductor technology using scanning spreading resistance microscopy J. Vac. Sci. Technol. B 22, 364 (2004); 10.1116/1.1638772 Two-dimensional ultrashallow junction characterization of metal-oxide-semiconductor field effect transistors with strained silicon J. Vac. Sci. Technol. B 22, 373 (2004); 10.1116/1.1627793Two dimensional dopant and carrier profiles obtained by scanning capacitance microscopy on an actively biased cross-sectioned metal-oxide-semiconductor field-effect transistor Carrier profiling of a 400 nm complementary metal-oxide-semiconductor device has been accomplished by combining metal-semiconductor capacitance-voltage profiling techniques with two-dimensional scanning probe microscopy. When a metal probe is brought into contact with a semiconductor, a space-charged depletion region and therefore a capacitor is formed at the junction. By applying a small ac voltage, the voltage derivative of the contact capacitance can be measured with a lock-in amplifier. The amplitude of the derivative signal is a function of the carrier concentration, and the sign gives the type of carrier. The present work concentrates on the two dimensional ͑2D͒ carrier profiling of a 400 nm metal-oxide-semiconductor field effect transistor. The results demonstrate that this technique is capable of quantitative 2D characterization of semiconductor devices.

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Quantitative two-dimensional dopant profiling of abrupt dopant profiles by cross-sectional scanning capacitance microscopy

Cited by 46 publications

References 0 publications

Recombination dynamics of traps in SiO 2 layer on Si by scanning capacitance microscopy

Recombination dynamics of traps in SiO 2 layer on Si by scanning capacitance microscopy

Inverse modeling applied to Scanning Capacitance Microscopy for improved spatial resolution and accuracy

Quantitative two-dimensional carrier profiling of a 400 nm complementary metal–oxide–semiconductor device by Schottky scanning capacitance microscopy

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