Concentric Ring Charge Storage Capacitor
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
A process is described resulting in the creation of a trench capacitor providing greater capacitance per unit area of silicon substrate than has heretofore been possible. The structure has dimensions smaller than can be defined by available photo techniques. Referring to Fig. 1, silicon substrate 2 is first coated with a film of silicon dioxide (SiO2) 4 plus a film of silicon nitride (Si3N4) 6. Standard photo and etching procedures are used to form an island of the deposited films 4 and 6. Exposed silicon substrate 2 is thermally oxidized to form SiO2 film 8. A conformal film of polysilicon 10 is then applied to result in the condition shown in Fig. 1. (Image Omitted) The polysilicon film 10 is reactive ion etched (RIE) to remove film 10 everywhere except on island edges, as shown in Fig. 2.