scholarly journals Semi-Automated Extraction of the Distribution of Single Defects for nMOS Transistors

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 446
Author(s):  
Bernhard Stampfer ◽  
Franz Schanovsky ◽  
Tibor Grasser ◽  
Michael Waltl
Keyword(s):  
Field Effect Transistors ◽  
Bimodal Distribution ◽  
Oxide Semiconductor ◽  
Vertical Position ◽  
Trap Level ◽  
Operating Characteristics ◽  
Large Area ◽  
Switching Speed ◽  
Oxide Defects ◽  
The Impact

Miniaturization of metal-oxide-semiconductor field effect transistors (MOSFETs) is typically beneficial for their operating characteristics, such as switching speed and power consumption, but at the same time miniaturization also leads to increased variability among nominally identical devices. Adverse effects due to oxide traps in particular become a serious issue for device performance and reliability. While the average number of defects per device is lower for scaled devices, the impact of the oxide defects is significantly more pronounced than in large area transistors. This combination enables the investigation of charge transitions of single defects. In this study, we perform random telegraph noise (RTN) measurements on about 300 devices to statistically characterize oxide defects in a Si/SiO 2 technology. To extract the noise parameters from the measurements, we make use of the Canny edge detector. From the data, we obtain distributions of the step heights of defects, i.e., their impact on the threshold voltage of the devices. Detailed measurements of a subset of the defects further allow us to extract their vertical position in the oxide and their trap level using both analytical estimations and full numerical simulations. Contrary to published literature data, we observe a bimodal distribution of step heights, while the extracted distribution of trap levels agrees well with recent studies.

Insight into Channel Conduction Mechanisms of 4H-SiC(0001) MOSFET Based on Temperature-Dependent Hall Effect Measurement

2020 ◽  
Vol 1004 ◽  
pp. 620-626
Author(s):  
Hironori Takeda ◽  
Mitsuru Sometani ◽  
Takuji Hosoi ◽  
Takayoshi Shimura ◽  
Hiroshi Yano ◽  
...  
Keyword(s):  
Hall Effect ◽  
Field Effect ◽  
Elevated Temperatures ◽  
Field Effect Transistors ◽  
Free Carrier ◽  
Oxide Semiconductor ◽  
Thermal Excitation ◽  
Temperature Dependent ◽  
Conduction Mechanisms ◽  
The Impact

Temperature-dependent Hall effect measurements were conducted to investigate the channel conduction mechanisms of 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). This method allows us to discriminate the impact of the density of mobile (free) carriers in the inversion channels and their net mobility on the performance of SiC MOSFETs. It was found that, while the free carrier ratio of SiC MOSFETs with conventional gate oxides formed by dry oxidation is below 4% at 300 K, increasing the free carrier ratio due to thermal excitation of trapped electrons from SiO2/SiC interfaces leads to an unusual improvement in the field-effect mobility of SiC MOSFETs at elevated temperatures. Specifically, a significant increase in free carrier density surpasses the mobility degradation caused by phonon scattering for thermally grown SiO2/SiC interfaces. It was also found that, although nitrogen incorporation in SiO2/SiC interfaces increases the free carrier ratio typically up to around 30%, introduction of an additional scattering factor associated with interface nitridation compensates for the moderate amount of thermally generated mobile carriers at high temperatures, indicating a fundamental drawback of nitridation of SiO2/SiC interfaces. On the basis of these findings, we discuss the channel conduction mechanisms of SiC MOSFETs.

scholarly journals Nonlinearity Analysis of Quantum Capacitance and its Effect on Nano-Graphene Field Effect Transistor characteristics

2021 ◽  
Author(s):  
MUNINDRA MUNINDRA ◽  
DEVA NAND
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
Drain Current ◽  
Charge Carrier Concentration ◽  
Single Layer Graphene ◽  
Quantum Capacitance ◽  
Large Area ◽  
Source Voltage ◽  
Current Calculation ◽  
The Impact

Abstract A simple, compact, and fundamental physics-based quasi-analytic model for Single layer graphene field effect transistors (GFETs) with large area graphene is presented in which the quantum mechanical density gradient method is utilised. The basic device physics of the two-dimensional (2D) graphene channel is studied analytically. This modeling leads to the precise drain current calculation of the GFETs. The drain current calculation for GFETs starts from charge carrier concentration, its density of states and quantum capacitance(QC). QC depends on the channel voltage as a function of gate to source voltage Vgs and drain to source voltage Vds primarily. The formulation of the drain current with velocity saturation has been done by the Monte Carlo simulation method. The performance of the analytical GFETs model is present the precise values of QC, its impact on drain current and transfer as well as output characteristics. The impact of QC at nanometer technology adds the nonlinearity to characteristics curves. The proposed method provides better results as compared with the previous analytical and simulated results.

Evaluation of the Impact of Al Atoms on SiO2/ SiC Interface Property by Using 4H-SiC n+-Channel Junctionless MOSFET

2019 ◽  
Vol 963 ◽  
pp. 171-174
Author(s):  
Hironori Takeda ◽  
Takuji Hosoi ◽  
Takayoshi Shimura ◽  
Heiji Watanabe
Keyword(s):  
Field Effect Transistors ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Electrical Characteristics ◽  
Al Doping ◽  
Oxidation Condition ◽  
Channel Mobility ◽  
Interface Property ◽  
Effective Mobility ◽  
The Impact

To investigate the impact of Al atoms on channel mobility at SiO2/SiC interface, we fabricated the junctionless metal-oxide-semiconductor field-effect transistors (MOSFETs), in which thin n+-SiC epitaxial layers with and without Al+ ion implantation were used as a channel, and compared their electrical characteristics. The effective mobility (meff) of n+-channel junctionless MOSFET without Al doping was estimated to be 14.9 cm2/Vs, which is higher than inversion-mode MOSFET fabricated with the same gate oxidation condition (3.1 cm2/Vs). The meff values of the MOSFETs with low Al doping concentration (5´1017 and 1´1018 cm-3) were almost the same as that of Al-free MOSFET, and the device with the highest Al doping (5´1018 cm-3) exhibited slight mobility degradation of about 15% compared to the other devices. Hall mobility in thick n+ layer with the highest Al doping was also slightly degraded, suggesting that Al atoms in the channel are not the major cause of degraded SiO2/SiC interface property.

TDDB Lifetime Enhancement in SiC-MOSFETs under Gate-Switching Pperation

2020 ◽  
Vol 1004 ◽  
pp. 665-670
Author(s):  
Eiichi Murakami ◽  
Tatsuya Takeshita ◽  
Kazuhiro Oda
Keyword(s):  
Dielectric Breakdown ◽  
Defect Density ◽  
Field Effect Transistors ◽  
Stress Test ◽  
Anomalous Behavior ◽  
Oxide Semiconductor ◽  
Continuous Increase ◽  
Hole Trapping ◽  
The Impact ◽  
Lifetime Enhancement

Gate oxide integrity (GOI) are the most important concern in automotive applications of SiC-metal-oxide-semiconductor field-effect transistors (MOSFETs). As well as for the so-called B-mode defect density reduction, the time-dependent dielectric breakdown (TDDB) mechanism including the B-mode should be clarified in comparison to Si-MOSFETs. We have reported an anomalous behavior in the form of a continuous increase in the gate current during a Fowler-Nordheim stress test of commercially available SiC-MOSFETs, which we attributed to hole trapping near the SiO2/SiC interface. In this paper, the impact of this phenomenon on the TDDB lifetime is investigated, and the effects of AC on the TDDB lifetime enhancement in SiC-MOSFET under gate-switching operations (1 kHz and 100 kHz, at room temperature) are reported.

scholarly journals Variability Predictions for the Next Technology Generations of n-type SixGe1−x Nanowire MOSFETs

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 643 ◽  
Author(s):  
Jaehyun Lee ◽  
Oves Badami ◽  
Hamilton Carrillo-Nuñez ◽  
Salim Berrada ◽  
Cristina Medina-Bailon ◽  
...  
Keyword(s):  
Quantum Transport ◽  
Field Effect Transistors ◽  
Tight Binding ◽  
Oxide Semiconductor ◽  
Line Edge Roughness ◽  
Metal Gate ◽  
Cross Sectional ◽  
Mass Approximation ◽  
Significant Difference ◽  
The Impact

Using a state-of-the-art quantum transport simulator based on the effective mass approximation, we have thoroughly studied the impact of variability on Si x Ge 1 − x channel gate-all-around nanowire metal-oxide-semiconductor field-effect transistors (NWFETs) associated with random discrete dopants, line edge roughness, and metal gate granularity. Performance predictions of NWFETs with different cross-sectional shapes such as square, circle, and ellipse are also investigated. For each NWFETs, the effective masses have carefully been extracted from s p 3 d 5 s ∗ tight-binding band structures. In total, we have generated 7200 transistor samples and performed approximately 10,000 quantum transport simulations. Our statistical analysis reveals that metal gate granularity is dominant among the variability sources considered in this work. Assuming the parameters of the variability sources are the same, we have found that there is no significant difference of variability between SiGe and Si channel NWFETs.

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