LDMOS (Lateral Diffused Metal Oxide Semiconductor) manufacturing method

Abstract

The invention discloses an LDMOS (Lateral Diffused Metal Oxide Semiconductor) manufacturing method, comprising the steps of: forming an LDMOS drain end in a BCD (Bipolar CMOS DMOS) process flow, and then carrying out ion implantation on the drain end for more than two times, wherein the angle between the direction of the ion implantation and a wafer axis gradually decreases, the energy of implanted ions gradually decreases and the dose of the implanted ions gradually increases. The LDMOS device manufactured by adopting the method has high working voltage, stable breakdown voltage and low cost.

Description

technical field [0001] The invention relates to a semiconductor process, in particular to an LDMOS manufacturing method. Background technique [0002] LDMOS (Lateral Diffused Medal-Oxide-Semiconductor, Lateral Diffused Medal-Oxide-Semiconductor) has relatively high operating voltage requirements. The operating voltage of the device is generally dependent on the carrier concentration and uniformity of the junction below the drain. In order to obtain a high working voltage of LDMOS, in the current BCD process platform, low-concentration doping is usually carried out under the drain of LDMOS, and then a long-term high-temperature push well is carried out to achieve a longer drift region. When the working voltage is increased, the depletion region Extend to the region with low doping concentration at the drain end to obtain a higher working voltage. This process mainly uses low-voltage wells or high-voltage wells. It requires long-term annealing of high-temperature furnace tube...

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Problems solved by technology

In order to obtain a high working voltage of LDMOS, in the current BCD process platform, low-concentration doping is usually carried out under the drain of LDMOS, and then a long-term high-temperature push well is carried out to achieve a longer drift region. When the working voltage is increased, the depletion region Extend to the region with low doping concentration at the drain end to obtain a higher working voltage. This process mainly uses low-voltage wells or high-voltage wells. It requires long-term annealing of high-temperature furnace tubes, which increases the thermal budget, process time and cost. The shape of the NP junction under the drain terminal is deep at the bottom and shallow on both sides, the carrier concentration distribution of the NP junction is uneven, the gradient distribution of the electric field strength is uneven, the breakdown voltage is unstable, and the operating voltage is limited.

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