Investigation Of Novel Integratable Lateral Power Devices And Discrete Vertical Power Devices

Power electronics is the key technology of power conversion.Power electronics converts one type of electric energy into another type of energy to realize the applications of various occasions.The most critical components of power electronics are power semiconductor devices.With the development of power electronics,integration,intellectualization,miniaturization have become the main development tendency.Smart Power Integrated Circuit?SPIC?integrates controlling circuit,driving circuit,protecting circuit and power switching devices into a single chip,which increases the level of intelligence and integration of the system.To integrate the power switching devices into the same chip,lateral power devices are the most common and the most viable option.However,due to that the current flows laterally near the surface of the device,the current density is small,and the power consumption during on-state is large.Therefore lateral devices are suitable for low-voltage and low-power applications.Compared with lateral power devices,discrete vertical power devices have larger current density and lower onstate voltage drop,which makes them suitable for high-voltage and high-power applications.Meanwhile,for system miniaturization,usually two or more discrete devices need to be integrated or packaged into a single chip or module,such as Reverse Conducting-Insulated Gate Bipolar Transistor: RC-IGBT.Therefore,both lateral and vertical power semiconductor devices have their own applications occasions.In view of the above analysis,based on Prof.Xingbi Chen's patents: Lateral Low-side and High-side High-voltage Devices and Composite Buffer Layer?later known as Super Junction: SJ?,lateral power devices and vertical power devices are mainly investigated and designed in this paper.The main work is presented in Chapter 2 to Chapter 5.Lateral devices are investigated in Chapter 2 to 3 and vertical devices are investigated in Chapter 4 to 5.The main contents are as follows:1.A novel p-type Lateral Double-diffused Metal-Oxide-Semiconductor field effect transistor?p-LDMOS?is proposed for high-voltage integrated circuits.The novel pLDMOS is named as "pseudo p-LDMOS".The "pseudo p-LDMOS" not only applies hole for conducting,but also applies electron for conducting by applying a simple autocontrolling circuit.Due to that the electron mobility is about three times of that of the hole,the specific on-resistance(R_on,sp)of the "pseudo p-LDMOS" is greatly reduced.2.Based on the above study of "pseudo p-LDMOS",an improved "pseudo p-LDMOS" for half-bridge or full-bridge output circuit is proposed.An electron inversion layer is introduced in the "pseudo p-LDMOS" to conduct current and the R_on,sp is tremendously reduced.The improved "pseudo p-LDMOS" has a comparable current capability of that of the n-LDMOS which applies electron accumulation layer to conduct current.These two kinds of LDMOSs are suitable for half-bridge or full-bridge output circuit.3.A new Super-Junction-U-shaped gate Metal-Oxide-Semiconductor field effect transistor?SJ-UMOS?whose body-diode has low reverse recovery charges(Q_rr)is proposed.In most of the applications of power MOSFET,an anti-parallel diode is needed for the freewheeling current.An intrinsic anti-parallel diode exists in MOSFET,called as body-diode.The Q_rr of body-diode of conventional SJ-UMOS is very large,because that the P-pillar in the drift region helps inject holes into the N-pillar.Large Q_rr leads to larger power consumption of the system.A new SJ-UMOS is proposed in this paper to stop the holes' injection from N-pillar.Thus the Q_rr is greatly reduced.4.A new RC-IGBT is proposed.Like power MOSFET,an anti-parallel diode is usually needed in most of the applications of IGBT.Current non-uniformity always exists in conventional RC-IGBT which may lead to latch-up of IGBT during the reverse recovery of body-diode.The new RC-IGBT proposed in this paper overcomes the above disadvantages and achieves a better tradeoff between on-state voltage drop(V_on)and turnoff loss(E_off).And the power consumption during reverse recovery is much smaller due to lower Q_rr of the body-diode.