SELF-ALIGNED TRENCH ISOLATED STRUCTURE
 Inventor: James M. Cleeves, Redwood City, Calif.
 Assignee: Cypress Semiconductor Corporation,
San Jose, Calif.
 Appl. No.: 08/666,754  Filed: Jun. 19, 1996
 Int. CI.7 H01L 21/04; H01L 21/4763
 U.S. CI 257/510; 257/622; 438/296
 Field of Search 257/510, 513,
257/622, 514; 438/296
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A trench-isolated active device and a method of forming a trench-isolated active device on a semiconductor substrate wherein the conductive layer of the device is self-aligned with an isolation trench is disclosed. The method includes applying a conductive layer over a dielectric layer (e.g., gate oxide), forming an opening in the conductive layer and the dielectric layer, forming a trench in the substrate corresponding to the opening, passivating the side walls of the trench with a dielectric material, and filling the trench with a dielectric material. The structure includes a semiconductor substrate having a trench defining a cell region, conductive material in the cell region and adjacent to the trench, and a layer of dielectric material on the side walls of the trench and on the conductive material adjacent to the trench. The invention further contemplates that the trench contains dielectric material, preferably soft glass. The conductive material layer is self-aligned to the isolation trench, so there is no overlap of the conductive material and the isolation trench, and the isolation trench may be a minimum width necessary to isolate the device.
4 Claims, 31 Drawing Sheets