HCF4007U Dual Complementary Pair plus Inverter

Integrated circuits do not get any simpler than this.  This is an HCF4007 made by ST with a week 27 1993 date code

ST HCF4007UAccording to the datasheet it can be, depending on the pin connections, either 3 inverters, a 3 input NOR or a 3 input NAND gate.

De-capping and you can see it is just 6 transistors! on a 1.47 mm x 1.35 mm die.ST HCF4007U die photo

(click on image for high resolution version)

It is barely an integrated circuit.  Even with my lack of skills I can reverse engineer this part

 

And the pin-out

 

 

 

 

There is one mystery to me.  The part is definitely CMOS as the datasheet specifies it, so  they must be polysilicon gate MOSFETs.  Yet if you look at this high magnification image of a transistor edge, I cannot see the polysilicon??

Thanks to Jeremy for providing the part.

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