Shallow trench isolation structure and forming method thereof

Abstract

The invention discloses a forming method of a shallow trench isolation structure. The forming method comprises the steps of: providing a substrate, wherein a shallow trench is formed in the substrate; forming a liner dielectric layer on the surface of the shallow trench; forming a first isolation dielectric layer on the surface of the liner dielectric layer; forming a second isolation dielectric layer which is filled in the whole shallow trench on the surface of the first isolation dielectric layer; and annealing the liner dielectric layer, the first isolation dielectric layer and the second isolation dielectric layer. Correspondingly, a shallow trench isolation structure formed by the method is further provided by the invention. The stress of the shallow trench isolation structure can be improved due to the shallow trench isolation structure and the forming method disclosed by the invention. Consequently, the migration rate of MOS (Metal Oxide Semiconductor) device trench region carriers is increased and the property of an MOS device is further improved.

Description

technical field [0001] The invention relates to semiconductor technology, in particular to a shallow trench isolation structure and a forming method thereof. Background technique [0002] Shallow Trench Isolation (STI) is a device isolation technology. The principle of forming the shallow trench isolation structure is to etch a shallow trench on the surface of the silicon substrate corresponding to the shallow trench, and silicon dioxide (SiO 2 ) into the shallow trench. [0003] As the semiconductor technology enters the deep sub-micron era, components below 0.18 microns, such as active area isolation layers of MOS circuits, are mostly produced using shallow trench isolation technology. More information on shallow trench isolation can be found in US Patent No. US7112513 Information about trench isolation technology. [0004] The specific process of the shallow trench isolation technology includes: forming a shallow trench on the substrate, the shallow trench is used to i...

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Problems solved by technology

[0006] However, the existing shallow trench isolation structure usually adopts high-density plasma-assisted chemical vapor deposition technology to fill the shallow trench with isolation medium, and the shallow trench isolation structure formed by high-density plasma-assisted chemical vapor deposition has a very high tensile stress on the channel. Small, for example, when the thickness of the isolation dielectric filled in the shallow trench is 9000 angstroms, the tensile stress produced by the shallow trench isolation structure on the channel region is only 140Mpa

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