A Novel DNW Isolation Structure for Reducing Device Size

At present, the overall supply and demand of chips is oversupply, and prices will maintain a downward trend. In order to reduce chip production costs and improve the core competitiveness of high-voltage platforms, reducing device size has become a top priority. However, the continuous reduction of the distance between DNW will lead to insufficient breakdown voltage between PN junction, and the device is easily broken down. At this time, it is very important to develop a new isolation structure to enhance the breakdown voltage. In this paper, based on the high pressure process with mature technology and mass production, the distance between DNW is reduced by 60%, and four kinds of DNW isolation structures are designed and combined with different ion implantation concentrations for the study of new DNW isolation structures. By adjusting the ion implantation concentration of PN junction and the drift region length of MOS tube, the influence of them on the breakdown voltage was investigated, and the method of increasing the breakdown voltage of MOS tube was explained. By reducing the concentration of N-type well, the breakdown voltage can reach up to 45V, which fully meets the design requirements of the device.