Double Diffused, Self-Aligned Electrically Alterable PNP
Original Publication Date: 1979-Mar-01
Included in the Prior Art Database: 2005-Feb-20
Several ways of making electrically programmable nonvolatile read-only memories (ROMs) have been disclosed in recent years. Typically, MOS and MNOS structures use hot electrons to charge up a floating gate (MOS) or become trapped in the Si(3)N(4) (MNOS) to either turn on a P channel or bias off an N channel FET. Bipolar ROM structures have been disclosed which program the P channel FET between the NPN base region and a P-isolation region. Future processes are incorporating double diffused PNPs to achieve improved performance. This article outlines a structure and method for fabricating a merged electrically programmable bipolar memory element, merging the double diffused PNP with an electrically programmable P channel MOSFET.