Isolated LDMOS device and manufacturing method thereof

Abstract

The invention discloses an isolated LDMOS device. A deep N-well is divided into an upper part and a lower part and comprises the source region, the drain region and the body region of the device. An isolating ring is formed around the deep N-well. The off-state breakdown voltage of an N pipe and the breakdown voltage of a parasite PN junction between the N-type region of the N pipe or a P pipe and the isolating ring are adjusted by the doping concentration of the upper part. The longitudinal punch-through voltage of a parasite PNP transistor of the N pipe or the P pipe is adjusted by the doping concentration of the lower part. According to the isolated LDMOS device, a process window of device design can be enlarged, integration of the N pipe and the P pipe is facilitated, and application of the N pipe and the P pipe in high-voltage side switches is facilitated; a high-voltage deep N-well is eliminated, and therefore photoetching of a layer is eliminated, the process cost is lowered, and the peripheral area of the device is reduced; the fluctuation influence to the off-state breakdown voltage of the N pipe from the change of the junction position of a high-voltage N-well and the deep N-well can be eliminated, and industrial production control is easy. The invention further discloses a manufacturing method of the isolated LDMOS device.

Description

technical field [0001] The invention relates to the field of manufacturing semiconductor integrated circuits, in particular to an isolation type LDMOS device; the invention also relates to a manufacturing method of the isolation type LDMOS device. Background technique [0002] In the prior art, isolated LDMOS devices are divided into N-type devices, that is, isolated NLDMOS devices, and P-type devices, that is, isolated LDPMOS devices; sometimes, isolated NLDMOS devices and isolated PLDMOS devices are integrated on the same substrate for preparation. [0003] like figure 1 Shown is a structural diagram of an existing isolated NLDMOS device; a deep N well 10 is formed in a P-type substrate 17 . A body region composed of a high-voltage P well 9 and a low-voltage P well 7 is formed in the deep N well 10, and a body region lead-out region 5 and a source region 3 are formed in the body region; The field oxide layer 11 is used to realize isolation between active regions, and the...

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Problems solved by technology

[0011] First, increasing the high-voltage N well 8 will add an additional layer of photolithography, which increases the process cost

[0012] Second, in order to improve the withstand voltage between the isolation well composed of the deep N well 10 and the high voltage N well 8 and the P-type substrate 17 to more than 1.2 times the operating voltage of the device drain, it is necessary to open the area size of the high voltage N well 8 stretched, which increases the peripheral dimensions of the device

[0013] second, figure 1 The position of the junction between the medium-deep N-well 10 and the high-voltage N-well 8 below the polysilicon gate 1 is sensitive to the off-state breakdown voltage of the N-tube, that is, the isolated NLDMOS device. When there is a small fluctuation, the position of the junction of the deep N well 10 and the high voltage N well 8 under the polysilicon gate 1 will also change slightly, and the breakdown voltage of the N transistor will have relatively large fluctuations, which is very important for industrial production control. unfavorable

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