Design Of 600V Reverse-conducting FS-IGBT

600V Insulated Gated Bipolar Transistor(IGBT) is widely used in induction cooking stoves, microwave ovens, air conditioning compressors, UPS and so on. In these applications, the IGBTs need anti-parallel diodes to follow current. Reverse conducting IGBT(RC-IGBT) eliminates the parasitic inductances between chip and chip, and reduces the chip size and package cost, since it integrates the unidirectional IGBT and the externally anti-paralleled fast recovery diode(FRD) into single chip. However, the RC-IGBT is prone to snapback in the on-state, and the design of RC-IGBT is more difficult than the conventional IGBT because of the trade-off between IGBT and FRD. A 600 V reverse conducting FS-IGBT which is base on the available technology, is designed as a pre-process for production.1. Design the available process flow of RC-IGBT. Firstly, the frontside structures of RC-IGBT including cells and terminations are made on the epitaxial wafer. And then, using backside grinding process, the wafer thickness is reduced to fulfill the backside process, including P-type collector and N-type shorting contacts process.2. Design the convential FS-IGBT. The initial parameters of RC-IGBT are obtained by designing the conventional FS-IGBT. The relationship between the breakdown voltage and epitaxial layer parameter, the relationship between threshold voltage and Pbody parameter, the relationship between on-state voltage drop and field stop layer parameter, the relationship between capacitors and cell width are demonstrated in this chapter.3. Design the RC-IGBT. The N+ shorting contacts are introduced into the backside of conventional FS-IGBT to form the RC-IGBT structure. And then, the epitaxial layer parameter, field stop layer parameter, the lifetime of carriers and the number of anti-paralleled cells are optimized to suppress the snapback phenomenon. The optimized RC-IGBT has forward and reverse conducting capacity, and the block state is similar to the VDMOS(Vertical Double-Diffused MOSFET). During the turn-off state, the backside N+ shorting contacts speed up to extract the carriers, so the fall time is decreased. The field limilating rings and field plates with N+ shorting contact at the backside are used as the termination structure of RC-IGBT. This N+ shorting contact is benefit to reduce the current path and suppress the local hot spot. Considering the uniform of current, a gate finger is introduced into the layout. And the backside N+ shorting contacts with a special angle are round. The toal area of the chip is 25mm2, containing active area 20mm2.The basic parameters of the optimized RC-IGBT as follows: breakdown voltage BV=733V, forward on-state voltage drop VCE=1.95 V, reverse on-state voltage drop VF=1.32V; the fall time under the IGBT mode tf=94ns, turn-off loss EOFF=670μJ; revcovery time under the FRD mode trr=202μs, reverse peak current IRRM=12A, recovery charge Qrr=1.47μC, softness factor S=0.41.