PROCESS OF SHALLOW TRENCH ISOLATING ACTIVE DEVICES TO AVOID SUB-THRESHOLD KINKS ARISING FROM CORNER EFFECTS WITHOUT ADDITIONAL PROCESSING

摘要

A shallow trench isolation (STI) process active devices avoids creating corner effects and sub-threshold kinks by a process which does not include additional steps or additional processing time. A predetermined material, such as polysilicon or doped polysilicon, is selected for a mask layer. The material reacts to form the same isolation material to a greater depth than the isolation material formed as a passivating trench layer at a silicon substrate, under simultaneous thermochemical reaction conditions. A relatively thicker protective layer is formed by the simultaneous reacition, and the protective layer projects the upper corners of the trench layer from removal when a padding layer is removed. The end result is a rounded protective corner which prevents the corner effect and the undesirable sub-threshold voltage-current non-linearities or kinks.