With the vigorous development of new energy, electric vehicles, artificial intelligence and other industries, the strong demand for power devices, especially super junction (SJ)MOSFET, has been driven to some extent. A new domestic semiconductor brand, represented by Alkaidsemi, launched a new G2.5 platform super junction MOSFET based on super junction multilayer epitaxy technology.

Based on the G2.5 platform, Alkaidsemi Micro introduced SJ MOSFET with two voltage levels (600 V-650 V) and multiple package series. Among them, many products packaged by TOLL have been mass-produced, and their compact size, low packaging resistance and parasitic inductance, excellent heat dissipation performance and high current carrying capacity can improve switching speed, reduce cost, and improve system efficiency and reliability, etc., and are widely used in various consumer, industrial and vehicle-level power electronic scenes.

By adjusting the concentration distribution of vertical PN junction, SJ MOSFET of G2.5 platform makes full use of the charge balance of super junction structure and optimizes the terminal structure, which greatly reduces the specific on-resistance while meeting the breakdown voltage, so that it can accommodate smaller resistance specifications in a smaller TOLL package, meet the requirements of application designers for higher power density, and achieve excellent electrical performance.

In order to adapt to high-frequency miniaturization application scenarios and reduce the impact of parasitic inductance of PCB. SJ MOSFET of G2.5 platform optimizes the gate structure, reduces the output capacitance and switching loss, and optimizes the reverse recovery ability to reduce the oscillation caused by reverse recovery. Compared with the previous generation, the gate charge (QG), Coss and turn-off time (TOFF) of SJ MOSFET, represented by the Toll-packaged AK3S60N355TMF (600V35.5Mω), are reduced by 20%, 40% and 60%, which greatly reduces the loss caused by parasitic parameters and improves the system efficiency.

In order to improve the efficiency of high frequency and high power density switching power supply, zero voltage ZVS soft switching technology (LLC, PSFB, etc.) is usually adopted. Because the new generation SJ MOSFET Coss is greatly reduced, the charging and discharging time of COSS capacitor is shorter in the process of ZVS soft switching, which can shorten the upper and lower dead time of the bridge arm and reduce the extra loss. In addition, the new generation of SJ MOSFET with Toll package not only optimizes the design of peripheral circuits through extra Kelvin connection, but also is not affected by source-level parasitic inductance, which reduces gate ringing and avoids the problem of mutual interference of loops, and further improves the stability of products.

The main parameters of SJ MOSFET, a new generation of G2.5 platform represented by AK3S60N355TMF, are shown in Figure 1.

Figure 1 Basic parameters of AK3S60N355TMF

The quality factor FOM (the product of on-resistance (RDS(on)) and gate charge (QG)) of AK3S60N355TMF is shown in Table 1, which is equivalent to the latest level of European and American first-tier manufacturers. With robust multi-layer epitaxy technology, the power density has reached the international first-class level.

In the application of 2kW communication power supply in a company, four AK3S60N355TMF are used in the LLC part of the whole bridge, and the measured efficiency is as follows:

The super-junction MOS series products of Alkaidsemi micro-multilayer epitaxial technology have the characteristics of low internal resistance, strong impact resistance, low junction capacitance, high reliability and stable quality. At present, this series of products has cooperated with many customers to help them manufacture better power supply.