A localized collector implant to improve uniformity of polysilicon bipolar transistors

It is shown that a localized collectivity implant can be used to improve the device performance as well as to increase the uniformity of device characteristics over the wafer of single polysilicon bipolar transistors. These advantages, which do not require additional masking steps, are important for both bipolar and BiCMOS technologies. Application of the localized collector implant in BiCMOS processes has the additional benefit that the NPN and MOS transistors can be optimized fairly independently. Some of the negative effects of the localized collectivity implant approach are examined