Termination Region Research Articles

Termination area design for reduced leakage current and improved ruggedness of HV IGBTs

Abstract A termination design which efficiently reduces leakage current and improves robustness of very high voltage insulated gate bipolar transistors (IGBTs) (>3.3 kV) without adversely affecting other device characteristics is presented here. Proposed design uses a selectively formed Buried N+ layer in the N-buffer under the termination region. Optimised placement of the N+ buried regions reduces carrier modulation in the termination area thus lowering the leakage current and reducing maximum temperature during the reverse bias safe operating area tests. This improves dynamic ruggedness of the IGBT without deteriorating other device characteristics.

Adiabatic–radiative shock systems in YSO jets and novae outflows

Context. The termination regions of non-relativistic jets in protostars and supersonic outflows in classical novae are non-thermal emitters. This has been confirmed by radio and gamma-ray detection, respectively. A two-shock system is expected to be formed in the termination region where the jet, or the outflow material, and the ambient medium impact. Radiative shocks are expected to form in these systems given their high densities. However, in the presence of high velocities, the formation of adiabatic shocks is also possible. A case of interest is when the two types of shocks occur simultaneously. Adiabatic shocks are more efficient at particle acceleration while radiative shocks strongly compress the gas. Furthermore, a combined adiabatic–radiative shock system is very prone to developing instabilities in the contact discontinuity, leading to mixing, turbulence, and density enhancement. Additionally, these dense non-relativistic jets and outflows are excellent candidates for laboratory experiments as demonstrated by magnetohydrodynamics scaling. Aims. We aim to study the combination of adiabatic and radiative shocks in protostellar jets and novae outflows. We focus on determining the conditions under which this combination is feasible together with its physical implications. Methods. We performed an analytical study of the shocks in both types of sources for a set of parameters by comparing cooling times and propagation velocities. We also estimated the timescales for the growth of instabilities in the contact discontinuity separating both shocks. We studied the hydrodynamical evolution of a jet colliding with an ambient medium with 2D numerical simulations, confirming our initial theoretical estimates. Results. We show that for a wide set of observationally constrained parameters, the combination of an adiabatic and a radiative shock is possible at the working surface of the termination region in jets from young stars and novae outflows. We find that instabilities are developed at the contact discontinuity, mixing the shocked materials. Additionally, we explore the magnetohydrodynamic parameter scaling required for studying protostellar jets and novae outflows using laboratory experiments on laser facilities. Conclusions. The coexistence of an adiabatic and a radiative shock is expected at the termination region of protostellar jets and novae outflows. This scenario is very promising for particle acceleration and gamma-ray emission. The parameters for scaled laboratory experiments are very much in line with plasma conditions achievable in currently operating high-power laser facilities. This provides a new means for studying novae outflows that has never been considered before.

Experiment and analysis of repetitive avalanche low-current stress on 4H-SiC power devices

As a kind of 4H-SiC power device, the junction barrier Schottky (JBS) rectifiers, only containing the transition p + implantation region at the edge of the active region in the termination region, are adopted and fabricated to analyze the effect of the repetitive avalanche low-current stress on the SiO2/4H-SiC interfacial state of the devices. The breakdown voltage (BV) of the device shifts after the repetitive avalanche current stress, which results from the electron injects into the SiO2/4H-SiC interface and trapped by the interface states. Meanwhile, there is a tradeoff between the quantities of the trapped and de-trapped electrons by the SiO2/4H-SiC interface states when the BV reaches its saturated value. The junction temperature, total amount of carriers generated in the single avalanche event and repetitive total avalanche energy, affected by the pulse period (T), pulse number and turn-on period (D), are the key factors that affect the level of the BV shift.

X-ray hot spots in the eastern ear of the supernova remnant W 50 and the microquasar SS 433 system

Abstract We examined the X-ray and radio spatial structure at the eastern ear of the W 50/SS 433 system to clarify a characteristic feature of the termination region of the SS 433 jet, and found that a hot spot ahead of the filament structure, which is considered to be a terminal shock of the SS 433 eastern jet, is clearly different from a single point source. The detailed spatial structure of the X-ray emission is finely resolved by Chandra observations, showing that there are two sources. By comparing the point-spread function of Chandra with the radial profiles of the two sources, the northern one is clearly more extended than a point source while the other seems marginally extended. Since there are no point sources nearby, the northern hot spot is likely a localized diffuse source. The northern hot spot spatially corresponds to the peak of the radio emission. Its spatial correlation is confirmed by an X-ray image using XMM-Newton. The X-ray spectra of the two sources are reproduced by a single absorbed power-law but the column density of the northern part is larger by a factor of ∼3. When a radiation model comprising synchrotron emission and inverse Compton emission is applied to the spectral energy distribution of the northern hot spot, the emission from this spot can be explained by the radiation from an electron population accelerated up to 30 TeV in a magnetic field strength of B ≲ 50 μG. This model also agrees with the radio and X-ray data, as well as the upper limit of gamma-ray emission obtained by the Fermi satellite.

Experimental and computational assessment of disbond growth and fatigue life of bonded joints and patch repairs for primary airframe structures

The applicability of a damage slow growth management strategy to bonded joints/patch repairs of primary aircraft structures was evaluated through an experimental and computational study. Fatigue tests were conducted to investigate the entire process of disbond growth from initiation up to joint ultimate failure. The residual static strength of the joint as a function of disbond length was established using finite element modelling, in which the mesh size was calibrated using the static strength of the specimens measured in room temperature and dry (RD) and hot-wet (HW) conditions, based on the characteristic distance approach. A virtual crack close technique (VCCT) approach was utilised to assess the strain energy release rates (SERRs) as a function of disbond crack length. The measured disbond growth rates were correlated with the SERRs using a modified Paris law that enabled prediction of joint fatigue life. The fatigue test results indicated that for a joint having a sufficient static strength safety margin under a typical fatigue loading that would propagate disbond, the disbond growth would be stable in a particular length range. Thus, the slow growth approach would be feasible for a bonded joint/patch repairs if the patch is designed to be sufficiently large to allow extended damage propagation (whilst in the case when patch size must be limited, safe-life design for the patch termination region in critical repairs must be considered. Should disbond growth occur in this case, the joint must be repaired or replaced). The work presented in this paper validated the framework/procedure proposed previously by the authors (Tanulia et al., 2020) for managing damage slow growth in bonded joints/patch repairs. In the last part of this paper the planned follow-on research is briefly described.

Optimizing performance and yield of vertical GaN diodes using wafer scale optical techniques

To improve the manufacturing of vertical GaN devices for power electronics applications, the effects of defects in GaN substrates need to be better understood. Many non-destructive techniques including photoluminescence, Raman spectroscopy and optical profilometry, can be used to detect defects in the substrate and epitaxial layers. Raman spectroscopy was used to identify points of high crystal stress and non-uniform conductivity in a substrate, while optical profilometry was used to identify bumps and pits in a substrate which could cause catastrophic device failures. The effect of the defects was studied using vertical P-i-N diodes with a single zone junction termination extention (JTE) edge termination and isolation, which were formed via nitrogen implantation. Diodes were fabricated on and off of sample abnormalities to study their effects. From electrical measurements, it was discovered that the devices could consistently block voltages over 1000 V (near the theoretical value of the epitaxial layer design), and the forward bias behavior could consistently produce on-resistance below 2 mΩ cm2, which is an excellent value considering DC biasing was used and no substrate thinning was performed. It was found that high crystal stress increased the probability of device failure from 6 to 20%, while an inhomogeneous carrier concentration had little effect on reverse bias behavior, and slightly (~ 3%) increased the on-resistance (Ron). Optical profilometry was able to detect regions of high surface roughness, bumps, and pits; in which, the majority of the defects detected were benign. However a large bump in the termination region of the JTE or a deep pit can induce a low voltage catastrophic failure, and increased crystal stress detected by the Raman correlated to the optical profilometry with associated surface topography.

The Optimization of 3.3 kV 4H-SiC JBS Diodes

The article reports a comprehensive study optimizing the OFF- and ON-state characteristics of 3.3 kV junction barrier Schottky (JBS) diodes made using nickel, titanium, and molybdenum contact metals. In this design, the same implants used in the optimized termination region are used to form the P-regions in the JBS active area. The width and spacing of the P-regions are varied to optimize both the ON- and OFF-state of the device. All the diodes tested displayed high blocking voltages and ideal turn-on characteristics up to the rated current of 2 A. However, the leakage current and the Schottky barrier height (SBH) were found to scale with the ratio of Schottky to p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> regions. Full Schottkys, without p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> regions, and those with very wide Schottky regions had the lowest SBH (1.61 eV for Ni, 1.11 eV for Mo, and 0.87 eV for Ti) and the highest leakage. Those diodes with the lowest Schottky openings of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 ~\mu \text{m}$ </tex-math></inline-formula> had the lowest OFF-state leakage, but they suffered severe pinching from the surrounding p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> regions, increasing their SBH. The best performing JBS diodes were Ni and Mo devices with the narrowest pitch, with the p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> implants/Schottky regions both <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 ~\mu \text{m}$ </tex-math></inline-formula> wide. These offered the best balanced device design, with excellent OFF-state performance, while the Schottky ratio guaranteed a relatively low forward voltage drop.

Physical mechanism of field modulation effects in ion implanted edge termination of vertical GaN Schottky barrier diodes

In this study, the physical properties of F ion-implanted GaN were thoroughly studied, and the related electric-field modulation mechanisms in ion-implanted edge termination were revealed. Transmission electron microscopy results indicate that the ion-implanted region maintains a single-crystal structure even with the implantation of high-energy F ions, indicating that the high resistivity of the edge termination region is not induced by amorphization. Alternately, ion implantation-induced deep levels could compensate the electrons and lead to a highly resistive layer. In addition to the bulk effect, the direct bombardment of high-energy F ions resulted in a rough and nitrogen-deficient surface, which was confirmed via atomic force microscopy (AFM) and X-ray photoelectron spectroscopy. The implanted surface with a large density of nitrogen vacancies can accommodate electrons, and it is more conductive than the bulk in the implanted region, which is validated via spreading resistance profiling and conductive AFM measurements. Under reverse bias, the implanted surface can spread the potential in the lateral direction, whereas the acceptor traps capture electrons acting as space charges, shifting the peak electric field into the bulk region in the vertical direction. As a result, the Schottky barrier diode terminated with high-energy F ion-implanted regions exhibits a breakdown voltage of over 1.2 kV.

Identification of de novo mutations for ARID1B haploinsufficiency associated with Coffin\u2013Siris syndrome 1 in three Chinese families via array-CGH and whole exome sequencing

BackgroundCoffin–Siris syndrome (CSS) is a multiple malformation syndrome characterized by intellectual disability associated with coarse facial features, hirsutism, sparse scalp hair, and hypoplastic or absent fifth fingernails or toenails. CSS represents a small group of intellectual disability, and could be caused by at least twelve genes. The genetic background is quite heterogenous, making it difficult for clinicians and genetic consultors to pinpoint the exact disease types.MethodsArray-Comparative Genomic Hybridization (array-CGH) and whole exome sequencing (WES) were applied for three trios affected with intellectual disability and clinical features similar with those of Coffin–Siris syndrome. Sanger sequencing was used to verify the detected single-nucleotide variants (SNVs).ResultsAll of the three cases were female with normal karyotypes of 46, XX, born of healthy, non-consanguineous parents. A 6q25 microdeletion (arr[hg19]6q25.3(155,966,487–158,803,979) × 1) (2.84 Mb) (case 1) and two loss-of-function (LoF) mutations of ARID1B [c.2332 + 1G > A in case 2 and c.4741C > T (p.Q1581X) in case 3] were identified. All of the three pathogenic abnormalities were de novo, not inherited from their parents. After comparison of publicly available microdeletions containing ARID1B, four types of microdeletions leading to insufficient production of ARID1B were identified, namely deletions covering the whole region of ARID1B, deletions covering the promoter region, deletions covering the termination region or deletions covering enhancer regions.ConclusionHere we identified de novo ARID1B mutations in three Chinese trios. Four types of microdeletions covering ARID1B were identified. This study broadens current knowledge of ARID1B mutations for clinicians and genetic consultors.

Complex Structure of the Eastern Lobe of the Pictor A Radio Galaxy: Spectral Analysis and X-Ray/Radio Correlations

Abstract Here we present detailed analysis of the distinct X-ray emission features present within the eastern radio lobe of the Pictor A galaxy, around the jet termination region, utilizing the data obtained from the Chandra X-ray Observatory. Various emission features have been selected for the study based on their enhanced X-ray surface brightness, including five sources that appear pointlike, as well as three extended regions, one characterized by a filamentary morphology. For those, we perform a basic spectral analysis within the 0.5–7 keV range. We also investigate various correlations between the X-ray emission features and the nonthermal radio emission, utilizing the high-resolution radio maps from the Very Large Array at gigahertz frequencies. The main novel findings following from our analysis concern the newly recognized bright X-ray filament located upstream of the jet termination region, extending for at least 30 kpc (projected), and inclined with respect to the jet axis. For this feature, we observe a clear anticorrelation between the X-ray surface brightness and the polarized radio intensity, as well as a decrease in the radio rotation measure with respect to the surroundings. We speculate on the nature of the filament, in particular addressing a possibility that it is related to the presence of a hot X-ray-emitting thermal gas, only partly mixed with the nonthermal radio/X-ray-emitting electrons within the lobe, combined with the reversals in the lobe’s net magnetic field.

Investigation of breakdown voltage degradation in low-voltage narrow gate trench MOSFET by edge termination optimization

In this paper, we investigate breakdown voltage degradation in a 25 V low-voltage narrow gate (NG) shield-gate trench MOSFET (NG-SGTMOS). Experiments and simulations based on Technology Computer-Aided Design (TCAD) indicate that electric field crowding and parasitic bipolar junction transistor (BJT) punch-through are responsible for the degradation of the device breakdown characteristic. To address these issues, two critical parameters, t 1 and t 2, are optimized in the layout of the transition and termination regions of the experimental NG-SGTMOS. It is demonstrated that electric field crowding induced by excessive and non-full depletion in edge termination is successfully eliminated at t 1 = 0.6 μm. Moreover, when improving t 2 beyond 0.2 μm, the soft breakdown characteristic owing to parasitic npn-BJT punch-through can be suppressed. As a result, the breakdown voltage stability of the proposed low-voltage NG-SGTMOS is improved.

Competitive binding of MatP and topoisomerase IV to the MukB hinge domain.

Structural Maintenance of Chromosomes (SMC) complexes have ubiquitous roles in compacting DNA linearly, thereby promoting chromosome organization-segregation. Interaction between the Escherichia coli SMC complex, MukBEF, and matS-bound MatP in the chromosome replication termination region, ter, results in depletion of MukBEF from ter, a process essential for efficient daughter chromosome individualization and for preferential association of MukBEF with the replication origin region. Chromosome-associated MukBEF complexes also interact with topoisomerase IV (ParC2E2), so that their chromosome distribution mirrors that of MukBEF. We demonstrate that MatP and ParC have an overlapping binding interface on the MukB hinge, leading to their mutually exclusive binding, which occurs with the same dimer to dimer stoichiometry. Furthermore, we show that matS DNA competes with the MukB hinge for MatP binding. Cells expressing MukBEF complexes that are mutated at the ParC/MatP binding interface are impaired in ParC binding and have a mild defect in MukBEF function. These data highlight competitive binding as a means of globally regulating MukBEF-topoisomerase IV activity in space and time.

A systematic analysis of Trypanosoma brucei chromatin factors identifies novel protein interaction networks associated with sites of transcription initiation and termination.

Nucleosomes composed of histones are the fundamental units around which DNA is wrapped to form chromatin. Transcriptionally active euchromatin or repressive heterochromatin is regulated in part by the addition or removal of histone post-translational modifications (PTMs) by “writer” and “eraser” enzymes, respectively. Nucleosomal PTMs are recognized by a variety of “reader” proteins that alter gene expression accordingly. The histone tails of the evolutionarily divergent eukaryotic parasite Trypanosoma brucei have atypical sequences and PTMs distinct from those often considered universally conserved. Here we identify 65 predicted readers, writers, and erasers of histone acetylation and methylation encoded in the T. brucei genome and, by epitope tagging, systemically localize 60 of them in the parasite's bloodstream form. ChIP-seq shows that 15 candidate proteins associate with regions of RNAPII transcription initiation. Eight other proteins show a distinct distribution with specific peaks at a subset of RNAPII transcription termination regions marked by RNAPIII-transcribed tRNA and snRNA genes. Proteomic analyses identify distinct protein interaction networks comprising known chromatin regulators and novel trypanosome-specific components. Notably, several SET- and Bromo-domain protein networks suggest parallels to RNAPII promoter–associated complexes in conventional eukaryotes. Further, we identify likely components of TbSWR1 and TbNuA4 complexes whose enrichment coincides with the SWR1-C exchange substrate H2A.Z at RNAPII transcription start regions. The systematic approach used provides details of the composition and organization of the chromatin regulatory machinery in T. brucei and establishes a route to explore divergence from eukaryotic norms in an evolutionarily ancient but experimentally accessible eukaryote.

Nonrandom segregation of sister chromosomes by Escherichia coli MukBEF

Structural maintenance of chromosomes (SMC) complexes contribute to chromosome organization in all domains of life. In Escherichia coli, MukBEF, the functional SMC homolog, promotes spatiotemporal chromosome organization and faithful chromosome segregation. Here, we address the relative contributions of MukBEF and the replication terminus (ter) binding protein, MatP, to chromosome organization-segregation. We show that MukBEF, but not MatP, is required for the normal localization of the origin of replication to midcell and for the establishment of translational symmetry between newly replicated sister chromosomes. Overall, chromosome orientation is normally maintained through division from one generation to the next. Analysis of loci flanking the replication termination region (ter), which demark the ends of the linearly organized portion of the nucleoid, demonstrates that MatP is required for maintenance of chromosome orientation. We show that DNA-bound β2-processivity clamps, which mark the lagging strands at DNA replication forks, localize to the cell center, independent of replisome location but dependent on MukBEF action, and consistent with translational symmetry of sister chromosomes. Finally, we directly show that the older ("immortal") template DNA strand, propagated from previous generations, is preferentially inherited by the cell forming at the old pole, dependent on MukBEF and MatP. The work further implicates MukBEF and MatP as central players in chromosome organization, segregation, and nonrandom inheritance of genetic material and suggests a general framework for understanding how chromosome conformation and dynamics shape subcellular organization.

Simulation Study of Single-Event Burnout in 1.5-kV 4H-SiC JTE Termination

This brief presents 2-D numerical simulation results of a single-event burnout (SEB) in a 4H-silicon carbide (SiC) junction termination extension (JTE) termination structure of a power metal-oxide-semiconductor field-effect transistor (MOSFET). Using the rated 1.5-kV JTE termination structure, the most sensitive ion's strike position to SEB is proved to be the edge of the P <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> /P <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> JTE region. Due to the severe punchthrough of the electric field, the source contact region is found to the most sensitive region to induce an SEB event. The SEB performance of the JTE termination structure with a single buffer layer or multilayer buffer is evaluated. The results show that the electric field distribution in four buffer layers (FBLs) is the most uniform to achieve the best SEB performance. Therefore, by adding an optimal FBL design to the termination region, the SEB threshold voltage can be increased to 1210 V instead of the common structure's 250 V. The SEB safe operating area of the power MOSFET with an optimal FBL can increase more than three times compared with the common one.

6.5 kV SiC Power Devices with Improved Blocking Characteristics against Process Deviations

Edge termination structures that are insensitive to process deviations were investigated to obtain 6.5 kV SiC power devices with stable blocking characteristics. Edge terminations were designed and verified by a TCAD simulation in consideration of undesirable surface charge states and variation of the implantation window in the termination region. A constant-space floating guard ring (CS-FGR) was sensitive to the variation of the implantation window. A gradually increasing space (GIS) FGR was less sensitive to process deviations than the CS-FGR. We concluded that the GIS-FGR is sufficiently stable for use in high-voltage SiC devices at surface charge densities (Q<SUB>surf</SUB>/q) of 0 to −1 × 10<SUP>12</SUP> cm<SUP>−2</SUP> and implantation window variations of −0.3 to +0.3 μm. The optimized GIS-FGR exhibited a high breakdown voltage of over 8 kV at all the Q<SUB>surf</SUB>/q values and in the implantation window variation range considered in this paper.

Total-Ionizing-Dose Radiation-Induced Dual-Channel Leakage Current at Unclosed Edge Termination for High Voltage SOI LDMOS

Total-ionizing-dose (TID) radiation response on unclosed edge termination is investigated for high voltage silicon-on-insulator (SOI) laterally diffused metal-oxide-semiconductor (LDMOS) in this article. Radiation-induced dual-channel leakage current model is proposed to reveal the mechanism of leakage current generation at OFF-state. Radiation causes a mass of positive oxide trapped charges generated in field oxide (FOX) layer and buried oxide layer. Owing to the P-SOI layer with significantly low doping concentration, two inversion channels are formed at the surface and bottom in the edge termination region, which provides parallel conduction paths. Electrons from the source N+ are pulled down and flow along the bottom channel while punchthrough occurring. The radiation-induced leakage current could be suppressed by thinning FOX layer, increasing the doping concentration of the P-SOI layer, and thickening the SOI layer.

Tracking Escherichia coli DNA polymerase V to the entire genome during the SOS response

Ribonucleotides are frequently incorporated into DNA and can be used as a marker of DNA replication enzymology. To investigate on a genome-wide scale, how E. coli pol V accesses undamaged chromosomal DNA during the SOS response, we mapped the location of ribonucleotides incorporated by steric gate variants of pol V across the entire E. coli genome. To do so, we used strains that are deficient in ribonucleotide excision repair (ΔrnhB), deficient in pol IV DNA polymerase, constitutively express all SOS-regulated genes [lexA(Def)] and constitutively “activated” RecA* (recA730). The strains also harbor two steric gate variants of E. coli pol V (Y11A, or F10L), or a homolog of pol V, (pol VR391-Y13A). Ribonucleotides are frequently incorporated by the pol V-Y11A and pol VR391-Y13A variants, with a preference to the lagging strand. In contrast, the pol V-F10L variant incorporates less ribonucleotides and no strand preference is observed. Sharp transitions in strand specificity are observed at the replication origin (oriC), while a gradient is observed at the termination region. To activate RecA* in a recA+ strain, we treated the strains with ciprofloxacin and genome-wide mapped the location of the incorporated ribonucleotides. Again, the pol V-Y11A steric gate variant exhibited a lagging strand preference. Our data are consistent with a specific role for pol V in lagging strand DNA synthesis across the entire E. coli genome during the SOS response.

A Compact Trench-Assisted Space-Modulated JTE Design for High-Voltage 4H-SiC Devices

This article proposes a compact trench-assisted space-modulated junction termination extension (TSM-JTE) design for high-voltage 4H-silicon carbide (SiC) devices. In this design, trench structures are introduced into the JTE region to effectively split the termination region into three functional zones. The proposed termination structure is cost effective in terms of the chip area it occupies; for devices rated at 10 kV, the termination structure extends the edge of the device by only 250 μm. Requiring only one implant, it is relatively cheap to fabricate, while a wide implantation dose window endures that is relatively insensitive to variations in dose that may occur during processing. The same advantages occur at 20 kV, the TSM-JTE proving to have the best tradeoff between maximum breakdown voltage and implantation window, compared with other single implant termination designs, achieving this in 500 μm of termination length. At 3.3 kV, a 110-μm TSM-JTE retains its advantages over the other JTE designs, but floating field rings are expected to consume less area, though this is not the case at the higher voltages.

A Novel Ultralow R ON,sp Triple RESURF LDMOS With Sandwich n-p-n Layer

This article proposes a novel ultralow specific ON-resistance (RON,sp) triple reduced surface field (RESURF) lateral double-diffused MOSFET (LDMOS) with sandwich np-n layer. Compared with the conventional triple RESURF LDMOS with n-type top layer (NTTR LDMOS), the new structure is characterized by an additional N-buried layer below the P-buried layer. Due to the introduction of N-buried layer, the concentration of N-top layer will decrease to ensure charge balance, thus making the surface electric field distribution better and the higher additional doping introduced by N-top and N-buried layers can be achieved. The dose and implantation energy of n-p-n layers were simulated and optimized. Furthermore, in order to eliminate the premature avalanche breakdown occurring in the source-centered termination region, substrate termination technology (STT) is applied to avoid the high electric field peaks generated in the curved source region with small curvature radius. But the use of STT makes it easy to breakdown in the transitional region compared with the straight region. Therefore, the transitional region is studied and the crucial parameter AL in the layout of transitional region is also optimized. The fabricated device experimentally demonstrated improved performance with low R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON,sp</sub> of 78.3 mΩ·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and high breakdown voltage (BV) of 795 V, and the experimental R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON,sp</sub> is 26.8% lower than that of the conventional triple RESURF LDMOS (CTR LDMOS) and 10% lower than that of the NTTR LDMOS based on L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> = 67 μm, which can break the silicon limit of CTR and NTTR LDMOS and meet the demand of 700-V high-voltage integrated circuit applications.