Semiconductor device having a frontside contact and vertical trench isolation and method of fabricating same

Abstract

A method of forming a contact stud (36) and surrounding isolation trench (28) in a semiconductor-on-insulator (SOI) substrate (20). The method comprises: etching a contact hole (26) and a surrounding isolation trench (28) from an active layer (6) of a substrate (20) to an insulating layer (4); performing a mask on the trench (28), The contact hole (26) is then further etched into the bottom substrate layer (2); the trench (28) and the contact hole (26) are filled with undoped intrinsic polysilicon (34); and the contact hole (26) is then filled The polysilicon material is subjected to a doping process to form an in-situ highly doped contact column (36), while the material filling the trench (28) remains non-conductive. The method can simultaneously form the isolation trench and the contact column, thereby avoiding undue disturbance of the device manufacturing process.

Description

technical field

[0001] In general, the present invention relates to semiconductor devices with front-side contact and vertical trench isolation, and in particular, the present invention relates to an active semiconductor device with respect to a semiconductor-on-insulator (SOI—semiconductor-on-insulator) substrate Areas form contact pillars and separate trenches. Background technique

[0002] Often, especially in high voltage applications, it is desirable to completely electrically isolate active semiconductor devices from the underlying semiconductor substrate ("vertical" isolation) and adjacent active devices ("horizontal" isolation).

[0003] Vertical isolation of active devices is generally achieved by using a semiconductor-on-insulator (SOI) substrate, see figure 1 The SOI substrate shown comprises: a base semiconductor (usually silicon) substrate 2 with a buried insulator (usually silicon oxide) layer 4 formed on its upper surface; and an active bonding semiconductor ...

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