Abstract :
The inability to easily and consistently fabricate complementary NPN and PNP transistors in a single chip has been a major limitation in the design of monolithic integrated circuits. A solution to this processing problem is presented and the results obtained using this method are described. A method for producing dielectrically isolated n and p type collector regions of homogeneous uncompensated single crystal silicon is given and the resulting material properties are described. To produce the planar diffused NPN and PNP devices, a sequential diffusion flow process was used. First an antimony base diffusion was made for the PNP, then a boron base diffusion for the NPN, next a boron emitter diffusion, and finally a phosphorus emitter diffusion. By using this diffusion sequence and taking advantage of the differences in diffusion coefficients between antimony and boron and between heavily doped boron and heavily doped phosphorus, it is possible to obtain similar base and emitter profiles for both type devices. The advantage of this method lies in its simplicity arising from the fact that standard oxide masked diffusion techniques are used and all impurity doping is done in open tube diffusion setups using liquid impurity sources. The diffusion profiles and the final device characteristics which were obtained are presented and discussed.
