Forming method of locally oxidized silicon isolation

Abstract

The invention provides a forming method of locally oxidized silicon isolation. The forming method of locally oxidized silicon isolation comprises the following steps: a semiconductor substrate is provided, wherein a pad oxidation layer and a blocking layer are sequentially formed on the semiconductor substrate; a groove which penetrates through the pad oxidation layer and the blocking layer and stretches to the semiconductor substrate are formed; buffer layers are formed on the bottom surface and the lateral wall of the groove; oxidation process is conducted, locally oxidized silicon is formed, and the buffer layers are oxidized to form oxidized silicon through oxidation; and the buffer layers located on the two sides of the locally oxidized silicon and the pad oxidation layer are removed. The buffer layers are formed in the groove, and lateral invasion of oxygen atom is reduced. Furthermore, the buffer layers provide silicon materials for forming the locally oxidized silicon in follow-up process, and therefore consumption of substrate materials is reduced, and a beak effect is further reduced.

Description

technical field [0001] The invention relates to semiconductor manufacturing technology, in particular to a method for forming partial silicon oxide isolation. Background technique [0002] In the prior art, methods for forming an isolation structure mainly include a Local Oxidation of Silicon (LOCOS) isolation process and a Shallow Trench Isolation (STI) process. In the LOCOS isolation process, a silicon nitride layer is deposited on the surface of the semiconductor substrate, and then part of the silicon nitride layer is removed by etching to expose part of the substrate, and the exposed part of the substrate is oxidized to generate local oxidation silicon, active devices are formed in the substrate covered by the silicon nitride layer such that the different active devices are isolated by the local silicon oxide. Compared with the STI process, the local silicon oxide formed by the LOCOS isolation process has a larger thickness and better isolation effect, so it is general...

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Problems solved by technology

[0005] However, in the process of oxidizing the substrate, oxygen atoms will still invade the substrate from the interface between the substrate and the pad oxide layer, and the bird's beak effect is relatively large.

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