Semiconductor isolation structure and forming method thereof

Abstract

The invention is a method for forming a semiconductor isolation structure, comprising the steps of: providing a semiconductor substrate which is a silicon on insulated substrate; forming a sacrificial oxide layer on the semiconductor substrate; forming a mask on the sacrificial oxide layer, and patterning the mask to define an active region and a isolated region on the semiconductor substrate; implanting oxygen ions to the isolated region through the sacrificial oxide layer; removing the mask; annealing the semiconductor substrate to arrange the oxygen ions ions evenly, thus forming the isolation structure; and removing the sacrificial oxide layer. According to the invention, the process is simple, the complexity of current preparing process of a STI isolated structure is avoided, and the defect that stress exists between a lining oxide layer and a semiconductor substrate, and between a lining oxide layer and a silicon oxynitride layer is also overcome.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for forming a semiconductor isolation structure and the isolation structure. Background technique [0002] Semiconductor integrated circuits generally contain active regions and isolation regions between the active regions, which are formed prior to fabrication of the active devices. Methods for forming isolation regions in the prior art mainly include Local Oxygen Isolation (LOCOS) and Shallow Trench Isolation (STI). The LOCOS process is to deposit silicon oxide and silicon nitride layers on the surface of the wafer, and then etch the silicon nitride layer to form a trench, and grow an isolation oxide layer in the trench area. Due to the different thermal expansion properties between silicon nitride and silicon during the oxidation process, at the boundary between silicon nitride and silicon oxide, oxygen diffuses through silicon oxide to the bottom...

AI Technical Summary

Problems solved by technology

[0006] The formation method of the above-mentioned shallow trench isolation structure is relatively complicated, and there is stress between the liner oxide layer and the semiconductor substrate and between the liner oxide layer and the silicon oxynitride layer, and this internal stress will form defects in the active region ( defect) or cracks (cracks)

[0007] With the further development of technology, it is necessary to increase the density of devices in integrated circuits by reducing the size of devices. However, as the size of devices is further reduced, the complexity of the manufacturing process and the stress on the isolation structure and the semiconductor substrate and the isolation structure Issues that increasingly affect the performance of the device

[0008] In addition, the semiconductor substrate of the above-mentioned shallow trench isolation structure is silicon. After forming a semiconductor device such as a transistor on the semiconductor substrate, the channel layer of the transistor is located on the surface of the silicon substrate. For semiconductor devices of 65nm and below , the channel length of the transistor is relatively short, the source and drain in the substrate are very close, it is easy to cause the depletion layer of the transistor to penetrate, and the leakage current flows from the semiconductor silicon substrate, causing the transistor to lose the control function of switching current

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