Design of 700 V triple RESURF nLDMOS with low on-resistance

A 700 V triple RESURF nLDMOS with a low specific on-resistance of 100 mΩ.cm^2 is designed. Compared with a conventional double RESURF nLDMOS whose P-type layer is located on the surface of the drift region, the P-type layer of a triple RESURF nLDMOS is located within it. The difference between the locations of the P-type layer means that a triple RESURF nLDMOS has about a 30% lower specific on-resistance at the same given breakdown voltage of 700 V. Detailed research of the influences of various parameters on breakdown voltage, specific on-resistance, as well as process tolerance is involved. The results may provide guiding principles for the design of triple RESURF nLDMOS.

A new high voltage SOI LDMOS with triple RESURF structure

A novel triple RESURF（T-resurf） SOI LDMOS structure is proposed.This structure has a P-type buried layer.Firstly,the depletion layer can extend on both sides of the P-buried layer,serving as a triple RESURF and leading to a high drift doping and a low on-resistance.Secondly,at a high doping concentration of the drift region, the P-layer can reduce high bulk electric field in the drift region and enhance the vertical electric field at the drain side,which results in uniform bulk electric field distributions and an enhanced BV.The proposed structure is used in SOI devices for the first time.The T-resurf SOI LDMOS with BV = 315 V is obtained by simulation on a 6μm-thick SOI layer over a 2μm-thick buried oxide layer,and its R_（sp） is reduced from 16.5 to 13.8 mΩ·cm^2 in comparison with the double RESURF（D-resurf） SOI LDMOS.When the thickness of the SOI layer increases, T-resurf SOI LDMOS displays a more obvious effect on the enhancement of BV^2/R_（on）.It reduces R_（sp） by 25%in 400 V SOI LDMOS and by 38%in 550 V SOI LDMOS compared with the D-resurf structure.

Modeling of a triple reduced surface field silicon-on-insulator lateral double-diffused metal–oxide–semiconductor field-effect transistor with low on-state resistance

An analytical model for a novel triple reduced surface field（RESURF） silicon-on-insulator（SOI） lateral doublediffused metal–oxide–semiconductor（LDMOS） field effect transistor with n-type top（N-top） layer, which can obtain a low on-state resistance, is proposed in this paper. The analytical model for surface potential and electric field distributions of the novel triple RESURF SOI LDMOS is presented by solving the two-dimensional（2D） Poisson＇s equation, which can also be applied to single, double and conventional triple RESURF SOI structures. The breakdown voltage（BV） is formulized to quantify the breakdown characteristic. Besides, the optimal integrated charge of N-top layer（Q_（ntop）） is derived, which can give guidance for doping the N-top layer. All the analytical results are well verified by numerical simulation results,showing the validity of the presented model. Hence, the proposed model can be a good tool for the device designers to provide accurate first-order design schemes and physical insights into the high voltage triple RESURF SOI device with N-top layer.

700 V超低比导通电阻的LDMOS器件

LDMOS器件广泛应用于高压集成电路芯片中,由于常作为功率开关来使用,其主要的性能指标为击穿电压(VB)与比导通电阻(RON,sp)。然而,VB与RON,sp均强烈受制于漂移区长度及掺杂浓度,因此存在固有的矛盾关系。Triple RESURF技术被广泛使用于优化器件VB与RON,sp之间的矛盾关系。基于传统Triple RESURF技术,提出了一种新型Triple RESURF LDMOS结构,即在P-buried层的上方和下方引入了高浓度的N型掺杂层。相较于传统结构,该结构器件既可以避免表面杂质浓度较高带来的器件提前击穿,又可以降低同等电压下的比导通电阻。测试结果表明该结构可以达到VB=795V,RON,sp=78.3 mΩ·cm2,相比于传统结构的RON,sp降低了26.8%。