IGBT working principle

[Semicon Enthusiast]

Hello Guys,

I am currently trying to understand the principle how an IGBT works. I fully get how a MOSFET works and operates but for IGBT I have some problems in understanding. I checked now multiple youtube videos but no one answered me the following question:

This is an excerpt from the following video:

My problem in understanding is, why in the left and right "body region", there are two n-doped areas. One n doped region per body region would be enough or not? The channel is forming below the gate SiO2 layer (as drawn with the 3 rows of "-" below the gate metal). Why exactly are there two n doped areas in the left and right body region? This makes no sense to me.

I also watched three or four other videos where it was the same drawing, so it does not seem to be a thing specifically from this video.

Looking forward to replies.

Thanks,
Tobias

 

[EdgarSam]

Hello Tobias,

Only one n+ emitter implant is sufficient for the MOSFET operation. An IGBT is made of the repetition of identical cells as the one shown above. The second n+ emitter implants are the emitter implants of the next IGBT left and right cells.

 

[Semicon Enthusiast]

Hello Tobias,

Only one n+ emitter implant is sufficient for the MOSFET operation. An IGBT is made of the repetition of identical cells as the one shown above. The second n+ emitter implants are the emitter implants of the next IGBT left and right cells.

Hello EdgarSam,

ahh yes. Get it.

Thank you very much.

Tobias