Ultra-high voltage LDMOS (Laterally Diffused Metal Oxide Semiconductor) device structure and production method thereof

Abstract

The invention discloses an ultra-high voltage LDMOS (Laterally Diffused Metal Oxide Semiconductor) device structure which comprises a source terminal, a drain terminal, a high voltage drift region and a grid electrode channel. The source terminal is provided with a substrate trap; a surface of the high voltage drift region is provided with an inversion layer; two physically connected deep traps which are respectively used for placing the substrate trap and the inversion layer are also designed in an LDMOS; and a gap between the two deep traps is located near an LOCOS (Local Oxidation of Silicon) bird beak. The invention also discloses a production method of the ultra-high voltage LDMOS device structure. The production method of the ultra-high voltage LDMOS device structure comprises process steps such as designing mask blanks of the deep traps, performing photoetching, performing ion implantation, removing of photoresist and performing hot-push of traps. The ultra-high voltage LDMOS device structure and the production method of the ultra-high voltage LDMOS device structure have the advantages of improving electric field distribution near LOCOS, reducing peak electric fields, achieving the balance of N type charge and P type charge and achieving the purpose of improvement of a reverse breakdown voltage of a device on the basis of increasing no process step and cost due to the facts that a deep trap of the source terminal and a deep trap of the high voltage drift region are separated and are connected together through push-trap after the ion implantation and the gap of the deep traps is located under the LOCOS bird beak.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuit manufacturing, in particular to the structure and preparation process of an ultra-high voltage LDMOS device. Background technique [0002] The ultra-high voltage LDMOS device (laterally diffused metal oxide semiconductor, laterally diffused metal oxide semiconductor transistor) is a power device with a double-diffused structure, and its structure is as follows figure 1 shown. This technology is to implant twice in the same source / drain region, one implantation of arsenic (As) with a higher concentration, and the other implantation of boron (B) with a lower concentration, and then a high-temperature push process after the implantation, due to the diffusion of boron It is faster than arsenic, so it will diffuse farther along the lateral direction under the gate boundary, forming a channel with a concentration gradient - P well (PW), and the channel length is determined by the differe...

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Problems solved by technology

However, since the edge of the field oxygen is where the electric field is concentrated, the surface electric field under the bird's beak of LOCOS (local oxide silicon) is the strongest, and the field plate above the field oxygen of the LDMOS polycrystalline extension to the drift region is difficult to weaken the drift region. The surface electric field, at this time, the N-type impurities under the LOCOS bird's beak are difficult to be exhausted, so the breakdown voltage will become smaller, and the device will be easily broken down

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