Very Thin Dielectric Storage Cap in N-Skin Compatible Process
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Dynamic random-access memories (RAMs) in the range of 1 megabit to 4 megabits and beyond quite commonly have a diffused storage node and an implant of the opposite conductivity type, known as a HiC structure, added to the RAM cell to provide extra junction capacitance under the dielectric capacitance and also to provide a particle soft error rate reductions. One method of forming the diffused storage node is to implant dopant atoms into the storage dielectric and cause them to out-diffuse later in the process. This method is called an N-skin, which usually uses arsenic for the dopant atoms. This article describes a novel storage capacitor structure which uses the mask associated with the HiC implant for a dual purpose and allows the N-skin storage dielectric to shrink.