The Effect of Contact Boundary on Bulk Resistance in Hexagonal Shaped Source/Drain in FinFETs

JungHun Kim,SoYoung Kim 대한전자공학회 2015 ITC-CSCC :International Technical Conference on Ci Vol.2015 No.6

This paper analyzes the influence of contact boundary on bulk resistance in hexagonal shaped source/drain regions of FinFETs. FinFET structures have 3 dimensional source/drain regions which make the resistance modeling more challenging than that of planar MOSFETs. The resistance can be divided into extrinsic resistance components, Rcon, Rbulk, Rspr, and Rsh. TCAD analysis results show that the surrounding contact shows minimum contact resistance (Rcon) and bulk resistance (Rbulk). Also, increasing contact area makes the bulk resistance larger, whereas the contact resistance smaller. But the decrement of the resistance is relatively small in bulk resistance case. Finally, we demonstrate that surrounding contact minimizes both contact and bulk resistance.

표면막과 표면거칠기가 접촉 저항에 미치는 영향

이현철,이보라,유용훈,조용주 한국트라이볼로지학회 2019 한국윤활학회지(윤활학회지) Vol.35 No.1

In this study, we aim to analyze the effects of both contact layer properties and surface roughness on contact resistance. The contact has a great influence on performance in terms of electrical conduction and heat transfer. The two biggest factors determining contact resistance are the presence of surface roughness and the surface layer. For this reason we calculated the contact resistance by considering both factors simultaneously. The model of this study to calculate contact resistance is as follows. First, the three representative surface parameters for the GW model are obtained by Nayak's random process. Then, the apparent contact area, real contact area, and contact number of asperities are calculated using the GW model with the surface parameters. The contact resistance of a single surface layer is calculated using Mikic's constriction equation. The total contact resistance is approximated by the parallel connection between the same asperity contact resistances. The results of this study are as follows. The appropriate thickness with reduction effect for contact resistance is determined according to the difference in conductivity between the base layer and surface layer. It was confirmed that the standard deviation of surface roughness has the greatest influence on surface roughness parameters. The results of this study will be useful for selecting the surface material and surface roughness when the design considering the contact resistance is needed.

Effect of Thermal Annealing on Ni/Au Contact to p-GaN

이호성,문진영,김준호,안철현,조형균,이주영,김홍승 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

We deposited Ni (13 nm) / Au (30 nm) layers on p-GaN by using the dc sputtering method in order to produce low-resistivity Ohmic contacts. The Ni (13 nm) / Au (30 nm) contact layers were annealed in air for 15 min at various temperatures. The electrical and the structural properties of the Ni/Au contact to p-GaN were investigated. The current-voltage measurement showed that the resistance of the as-deposited sample was very high. However, the sample annealed at 600 ℃ showed Ohmic-like behavior with a specific contact resistance of 1.9 × 10−3 cm2. Further increasing the temperature caused the Ohmic-like behavior to be degraded. Transmission electron microscopy and Auger electron spectroscopy were used to characterize the interfacial structure between the Ni/Au electrode and the p-GaN layers. The Ni layer was in contact with the p-GaN before annealing. However, after annealing, the Au layer had diffused from the top layer to the interface. The Au layer on the p-GaN surface resulting from the indiffusion of Au atoms during annealing may contribute to effective Ohmic contact formation. We deposited Ni (13 nm) / Au (30 nm) layers on p-GaN by using the dc sputtering method in order to produce low-resistivity Ohmic contacts. The Ni (13 nm) / Au (30 nm) contact layers were annealed in air for 15 min at various temperatures. The electrical and the structural properties of the Ni/Au contact to p-GaN were investigated. The current-voltage measurement showed that the resistance of the as-deposited sample was very high. However, the sample annealed at 600 ℃ showed Ohmic-like behavior with a specific contact resistance of 1.9 × 10−3 cm2. Further increasing the temperature caused the Ohmic-like behavior to be degraded. Transmission electron microscopy and Auger electron spectroscopy were used to characterize the interfacial structure between the Ni/Au electrode and the p-GaN layers. The Ni layer was in contact with the p-GaN before annealing. However, after annealing, the Au layer had diffused from the top layer to the interface. The Au layer on the p-GaN surface resulting from the indiffusion of Au atoms during annealing may contribute to effective Ohmic contact formation.

Clean Interface Contact Using a ZnO Interlayer for Low-Contact-Resistance MoS₂ Transistors

Jang, Jisu,Kim, Yunseob,Chee, Sang-Soo,Kim, Hanul,Whang, Dongmok,Kim, Gil-Ho,Yun, Sun Jin American Chemical Society 2020 ACS APPLIED MATERIALS & INTERFACES Vol.12 No.4

<P>Two-dimensional transition metal dichalcogenides (TMDCs) have emerged as promising materials for next-generation electronics due to their excellent semiconducting properties. However, high contact resistance at the metal-TMDC interface plagues the realization of high-performance devices. Here, an effective metal-interlayer-semiconductor (MIS) contact is demonstrated, wherein an ultrathin ZnO interlayer is inserted between the metal electrode and MoS<SUB>2</SUB>, providing damage-free and clean interfaces at electrical contacts. Using TEM imaging, we show that the contact interfaces were atomically clean without any apparent damages. Compared to conventional Ti/MoS<SUB>2</SUB> contacts, the MoS<SUB>2</SUB> devices with a Ti/ZnO/MoS<SUB>2</SUB> contact exhibit a very low contact resistance of 0.9 kΩ μm. These improvements are attributed to the following mechanisms: (a) Fermi-level depinning at the metal/MoS<SUB>2</SUB> interface by reducing interface disorder and (b) presence of interface dipole at the metal/ZnO interface, consequently reducing the Schottky barrier and contact resistance. Further, the contact resistivity of a Ti/ZnO/MoS<SUB>2</SUB> contact is insensitive to the variation of ZnO thickness, which facilitates large-scale production. Our work not only elucidates the underlying mechanisms for the operation of the MIS contact but also provides a simple and damage-free strategy for conventional aggressive metal deposition that is potentially useful for the realization of large-scale 2D electronics with low-resistance contacts.</P> [FIG OMISSION]</BR>

Study of Ablation of Arc Contacts and Dynamic Contact Resistance in High Current Breaker

Licheng Xing,Xiaodong Zhang,Qingbin Tong,Gaoqi Xing 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3

The fault of power circuit breaker (PCB) can lead very serious problems, especially in high voltage–power grid. The structure of contacts may be composed of main contacts and arc contacts, and this structure can avoid ablation of main contacts efciently. It is necessary to study the eroded state of the arc contacts and the dynamic contact resistance of arc contacts to estimate the operating state of the PCB. The wear of contacts contains arc ablation and mechanical wear through the characteristics of contacts. The arc ablation is caused by the high temperature of the arc and the mechanical wear is caused by the mechanical friction of static and movable contacts. Some experiments have been done under diferent size of contacts and diferent current through them. The results show that the mechanical wear increases, sometimes heavier, with the increase of the size of fxed contacts and the decrease of the size of movable ones because the force between fxed and movable contacts becomes larger. The results also show that the ablation of arc contacts increases with the increase of current, especially when the current is up to 20 kA. With the high temperature of arc reaching the hardness point of copper, the arc ablation and mechanical erosion are increasing obviously since the contacts become soft and easy to wear. Another result of the study shows it is important to choose the material of contacts and the force between movable and fxed contacts. The harder and less resistance the material of contacts, the better the operating situation. To monitor the operating situation of the breaker, the dynamic contact resistance was measured 25 times. As a result, the dynamic contact resistance is sensitive to the current and increasing with the increase of continuous experiment time because of the increasing of metal ions. Furthermore, if the SF6 in the PCB is changes, the dynamic contact resistance would be changed. The dynamic contact resistance in this experiment varies substantially within the range of 80–250 μΩ at the current of 20 kA.

High performance of pentacene organic thin film transistors by doping of iodine on source/drain regions

Abdur, R.,Jeong, K.,Lee, M.J.,Lee, J. Elsevier Science 2013 Organic electronics Vol.14 No.4

Contact doping was conducted by iodine in a top contact configuration in a pentacene organic thin film transistor (OTFT), to investigate its effects on contact resistance and the resulting electrical performance. Iodine doping in the pentacene film caused the change of pentacene structure, thus leading to an increase in electrical anisotropy, i.e. ratio of lateral to vertical resistivity. The two resistive components of doped pentacene film underneath the Au contacts were major contributors to the contact resistance, and a model to explain the dependence of contact resistance on iodine doping was presented. Finally, OTFTs fabricated on iodine doped source/drain contacts exhibited high mobility of 1.078cm<SUP>2</SUP>/Vs, two times that of OTFTs with undoped contacts, due to the low contact resistance.

Method for contact resistivity measurements on highly phosphorus-doped silicon using a multiline transmission line model

Shin Hyunsu,Park Seran,Park Heungsoo,Ko Dae-Hong 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.4

As the size of a transistor decreases, the parasitic resistances of the transistor become dominant for contact resistance. In-situ phosphorus-doped epitaxial silicon with high doping concentrations has been used to reduce contact resistivity. In this study, we measured the contact resistivity of in-situ phosphorus-doped silicon using a circular transmission line model (CTLM). The distribution of the contact resistivity for films with high phosphorus concentrations was found to be about 400 times larger than that for films with low phosphorus concentrations. To explain the large distribution of the measured contact resistivity, the potential distribution and current flow in phosphorus-doped silicon films with various phosphorus concentrations were simulated using the CTLM and a transmission line model (TLM). In silicon films with high phosphorus doping concentrations, the greater effects of metal resistance and the vertical current reduced the accuracy of the extracted contact resistivity. A multiline transmission line model (ML–TLM) was proposed to improve the accuracy of the extracted contact resistivity at a given phosphorous concentration. The use of the ML–TLM increased the ratio of the contact resistance to the total resistance; thus, the effect of metal resistance was significantly reduced, and the accuracy of contact resistivity was improved.

SABiT 공법적용 인쇄회로기판의 은 페이스트 범프 크기 및 제작 조건에 따른 전기 저항 특성

송철호,김영훈,이상민,목지수,양용석 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.4

We investigated the resistance change behavior of SABiT (Samsung Advanced Bump interconnection Technology) technology-applied PCB (Printed Circuit Board) with the various bump sizes and fabrication conditions. Many testing samples with different bump size, prepreg thickness, number of print on the formation of Ag paste bump, were made. The resistance of Ag paste bump itself was calculated from the Ag paste resistivity and bump size, measured by using 4-point probe method and FE-SEM (Field Emission Scanning Electron Microscope), respectively. The contact resistance between Ag paste bump and conducting Cu line were obtained by subtracting the Cu line and bump resistances from the measured total resistance. It was found that the contact resistance drastically changed with the variation of Ag paste bump size and the contact resistance had the largest influence on total resistance. We found that the bump size and contact resistance obeyed the power law relationship. The resistance of a circuit in PCB can be estimated from this kind of relationship as the bump size and fabrication technique vary.

Study on the measurement accuracy of circular transmission line model for low-resistance Ohmic contacts on III-V wide band-gap semiconductors

Tong Liu,Rong Huang,Fangsen Li,Zengli Huang,Jian Zhang,Jianping Liu,Liqun Zhang,Shuming Zhang,An Dingsun,Hui Yang 한국물리학회 2018 Current Applied Physics Vol.18 No.7

The accuracy and error propagation for determining the low specific contact resistance of Ohmic contacts on IIIV wide band-gap semiconductors based on the circular transmission line model have been analyzed and the validity of this method is discussed in detail. The accuracy is more susceptible to the factors including data fitting method, electrical measurement technique and contact area correction. By using the equations of the original circular transmission line model to extract the fitting parameters, the calculation accuracy is much improved and the inapplicability of the linear least-square fitting is prevented. To further improve the accuracy, a four-probe current-voltage measurement technique was adopted to reduce the parasitic series resistances and the uncertainty bound, especially for the Ohmic contact with low sheet resistance of the semiconductor. Moreover, we have studied the size effect of contact pads of patterns and demonstrated that contact area correction is necessary for the semiconductor with high sheet resistance. A comprehensive error analysis is also performed to fully understand all the impact factors on this advanced method of specific contact resistance measurement, which is benefit for device performance evaluation and failure analysis.

고효율, 저가화 실리콘태양전지를 위한 Ni/Cu/Ag 금속전극의 특성 연구

이지훈(Ji-Hun Lee),조경연(Kyeng-yeon Cho),이수홍(Soo-hong Lee) 한국태양에너지학회 2009 한국태양에너지학회 학술대회논문집 Vol.- No.-

Crystlline silicon solar cells markets are increasing at rapid pace. now, crystlline silicon solar cells markets screen-printing solar cell is occupying. screen-printing solar cells manufacturing process are very quick, there is a strong point which is a low cost. but silicon and metal contact, uses Ag & Al pates. because of, high contact resistance, high series resistance and sintering inside process the electric conductivity decreases with 1/3. and In pastes ingredients uses Ag where 80∼90% is metal of high cost. because of low cost solar cells descriptions is difficult. therefore BCSC(Buried Contact Solar Cell) is developed. and uses light-induced plating, ln-line galvanization developed equipments. Ni/Cu matel contact solar cells researches. in Germany Fraunhofer ISE. In order to manufacture high-efficency solar cells, metal selections are important. metal materials get in metal resistance does small, to be electric conductivity does highly. efficiency must raise an increase with rise of the curve factor where the contact resistance of the silicon substrate and is caused by few with decrement of series resistance. Ni metal materials the price is cheap, Ti comes similar resistance. Cu and Ag has the electric conductivity which is similar. and Cu price is cheap. In this paper, Ni/Cu/Ag metal contact cell with screen printing manufactured, silicon metal contact comparison and analysis.