Drain Side Area-modulation Effect of Parasitic Schottky Diode on ESD Reliability for High Voltage P-channel Lateral-Diffused MOSFETs

An electrostatic discharge (ESD) event can negatively affect the reliability of integrated circuits. Therefore, improving on ESD immunity in high-voltage (HV) n-channel (n) lateral diffused metal–oxide–semiconductor field-effect transistor (HV nLDMOS) components through drain-side layout engineering was studied. This involved adjusting the operating voltage, improving the non-uniform turned-on phenomenon, and examining the effects of embedded-device structures on ESD. All proposed architectures for improving ESD immunity in this work were measured and evaluated using a transmission-line pulse system. The corresponding trigger voltage (Vt1), holding voltage (Vh) and secondary breakdown current (It2) results of the tested devices were obtained. This paper first addresses the drift-region length modulation to design different operating voltages, which decreased as the drift region length and shallow trench isolation (STI) length shrunk. When an HV nLDMOS device decreased to the shortest drift region length, the Vt1 and Vh values were closest to 21.85, and 9.27 V, respectively. The It2 value of a low-voltage operated device could be increased to a maximum value of 3.25 A. For the channel width modulation, increasing the layout finger number of an HV LDMOS device did not really help the ESD immunity that because it may suffer the problem of non-uniform turned-on phenomenon. Therefore, adjusting the optimized channel width was the best one method of improvement. Furthermore, to improve the low ESD reliability problem of nLDMOS devices, two structures were used to improve the ESD capability. The first was a drain side—embedded silicon-controlled rectifier (SCR). Here, the SCR PNP-arranged type in the drain side had the best ESD capability because the SCR path was short and had been prior to triggering; however, it also has a latch-up risk and low Vh characteristic. By removing the entire heavily doped drain-side N+ region, the equivalent series resistance in the drain region was increased, so that the It2 performance could be increased from 2.29 A to 3.98 A in the structure of a fully embedded drain-side Schottky diode. This component still has sufficiently high Vh behaviour. Therefore, embedding a full Schottky-diode into an HV nLDMOS in the drain side was the best method and was efficient for improving the ESD/Latch-up abilities of the device. The figure of merit (FOM) of ESD, Latch-up, and cell area considerations improved to approximately 80.86%.

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The reverse recovery characteristics of an SiC superjunction MOSFET with a p-type Schottky diode embedded at the drain side for improved reliability

Journal of Computational Electronics ◽

10.1007/s10825-021-01694-8 ◽

2021 ◽

Author(s):

Pavan Vudumula ◽

Siva Kotamraju

Keyword(s):

Schottky Diode ◽

Drain Side ◽

P Type

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Sensing and Reliability Improvement of Electrostatic-Discharge Transient by Discrete Engineering for High-Voltage 60-V n-Channel Lateral-Diffused MOSFETs with Embedded Silicon-Controlled Rectifiers

Sensors ◽

10.3390/s18103340 ◽

2018 ◽

Vol 18 (10) ◽

pp. 3340

Author(s):

Shen-Li Chen ◽

Yi-Cih Wu

Keyword(s):

High Voltage ◽

Field Effect Transistor ◽

Electrostatic Discharge ◽

Reference Sample ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Physical Parameters ◽

Reliability Improvement ◽

Drain Side ◽

Effect Transistor

High-voltage n-channel lateral-diffused metal-oxide-semiconductor field-effect transistor (nLDMOS) components, fabricated by a TSMC 0.25-m 60-V bipolar-CMOS-DMOS (BCD) process with drain-side embedded silicon-controlled rectifier (SCR) of the n-p-n-arranged and p-n-p-arranged types, were investigated, in order to determine the devices’ electrostatic discharge (ESD)-sensing behavior and capability by discrete anode engineering. As for the drain-side n-p-n-arranged type with discrete-anode manners, transmission–line–pulse (TLP) testing results showed that the ESD ability (It2 value) was slightly upgraded. When the discrete physical parameter was 91 rows, the optimal It2 reached 2.157 A (increasing 17.7% compared with the reference sample). On the other hand, the drain-side SCR p-n-p-arranged type with discrete-anode manner had excellent SCR behavior, and its It2 values could be increased to >7 A (increasing >281.9% compared with the reference DUT). Moreover, under discrete anode engineering, the drain-side SCR n-p-n-arranged and p-n-p-arranged types had clearly higher ESD ability, except for the few discrete physical parameters. Therefore, using the anode discrete engineering, the ESD dissipation ability of a high-voltage (HV) nLDMOS with drain-side SCRs will have greater effectiveness.

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Robust ESD-Reliability Design of 300-V Power N-Channel LDMOSs with the Elliptical Cylinder Super-Junctions in the Drain Side

Electronics ◽

10.3390/electronics9050730 ◽

2020 ◽

Vol 9 (5) ◽

pp. 730 ◽

Cited By ~ 1

Author(s):

Shen-Li Chen ◽

Pei-Lin Wu ◽

Yu-Jen Chen

Keyword(s):

High Voltage ◽

Field Effect Transistors ◽

Area Ratio ◽

Operating Conditions ◽

Elliptical Cylinder ◽

Drift Region ◽

Reference Device ◽

Drain Side ◽

Drain Region ◽

Original Reference

The weak ESD-immunity problem has been deeply persecuted in ultra high-voltage (UHV) metal-oxide-semiconductor field-effect transistors (MOSFETs) and urgently needs to be solved. In this paper, a UHV 300 V circular n-channel (n) lateral diffused MOSFET (nLDMOS) is taken as the benchmarked reference device for the electrostatic discharge (ESD) capability improvement. However, a super-junction (SJ) structure in the drain region will cause extra depletion zones in the long drain region and reduce the peak value of the channel electric field. Therefore, it may directly increase the resistance of the device to ESD. Then, in this reformation project for UHV nLDMOSs to ESD, two strengthening methods were used. Firstly, the SJ area ratio changed by the symmetric eight-zone elliptical-cylinder length (X) variance (i.e., X = 5, 10, 15 and 20 μm) is added into the drift region of drain side to explore the influence on ESD reliability. From the experimental results, it could be found that the breakdown voltages (VBK) were changed slightly after adding this SJ structure. The VBK values are filled between 391 and 393.5 V. Initially, the original reference sample is 393 V; the VBK changing does not exceed 0.51%, which means that these components can be regarded as little changing in the conduction characteristic after adding these SJ structures under the normal operating conditions. In addition, in the ESD transient high-voltage bombardment situation, the human-body model (HBM) capability of the original reference device is 2500 V. Additionally, as SJs with the length X high-voltage P-type well (HVPW) are inserted into the drain-side drift region, the HBM robustness of these UHV nLDMOSs increases with the length X of the HVPW. When the length X (HVPW) is 20 μm, the HBM value can be upgraded to a maximum value of 5500 V, the ESD capability is increased by 120%. A linear relationship between the HBM immunity level and area ratio of SJs in the drains side in this work can be extracted. The second part revealed that, in the symmetric four-zone elliptical cylinder SJ modulation, the HBM robustness is generally promoted with the increase of HVPW SJ numbers (the highest HBM value (4500 V) of the M5 device improved by 80% as compared with the reference device under test (DUT)). Therefore, from this work, we can conclude that the addition of symmetric elliptical-cylinder SJ structures into the drain-side drift region of a UHV nLDMOS is a good strategy for improving the ESD immunity.

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