Design of high-frequency substrate noise isolation in BiCMOS technology

A high-frequency noise isolation structure and a method for forming the same are provided. The noise isolation structure isolates a first device region and a second device region over a semiconductor substrate. The noise isolation structure preferably includes a sinker region substantially encircling a first device region, a buried layer underlying the first device region and joining the sinker region, a deep guard ring substantially encircling the sinker region, and a deep trench oxide region substantially encircling the sinker region. The isolation structure further includes a wide guard ring between the first and the second device regions. The sinker region and the buried region preferably have a high impurity concentration. Integrated circuits to be noise decoupled are preferably formed in the respective first and second device regions.