Method for manufacturing deep-trench isolation structure

Abstract

The invention provides a method for manufacturing a deep-trench isolation structure. The method at least comprises the following steps of S1, supplying a substrate, forming at least one deep trench in the substrate, and filling the deep trench with polycrystalline silicon; S2, performing annealing for restructuring the grain structure of the polycrystalline silicon; S3, performing etching back on the polycrystalline silicon through mixed gas which is composed of Cl2 and HBr, thereby removing the redundant polycrystalline silicon outside the deep trench; and S4, performing etching back on the polycrystalline silicon by means of SF6 as etching gas, thereby obtaining a flat polycrystalline silicon surface at top of the deep trench. The method for manufacturing the deep-trench isolation structure has advantages of improving polycrystalline silicon seaming in the deep trench and on the surface of the deep trench, improving polycrystalline silicon fusion degree, reducing the etching-back amount of the polycrystalline silicon in realizing the flat and smooth polycrystalline silicon surface on the top of the deep trench, and reducing top sinking degree of the deep trench.

Description

technical field [0001] The invention belongs to the field of semiconductor manufacturing and relates to a method for manufacturing a deep trench isolation structure. Background technique [0002] Deep trench isolation technology refers to carving a trench with a depth greater than 3 microns between devices, backfilling it with silicon dioxide or polysilicon, and planarizing it with chemical mechanical polishing (CMP). The advantages of deep trench isolation are: 1) Reduced device area; 2) Reduced parasitic capacitance between emitter and substrate; 3) Increased breakdown voltage between collectors of bipolar transistors. The disadvantage is that the process is complicated and the cost is high. [0003] With the development of science and technology, deep trench isolation technology is more and more applied to many special devices, such as CMOS image sensors, bipolar junction transistors (BJT) and power devices, which serve as the isolation between adjacent units in the devi...

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Problems solved by technology

[0006] In view of the shortcomings of the prior art described above, the object of the present invention is to provide a method for manufacturing a deep trench isolation structure, which is used to solve the serious seams and sinking on the top polysilicon surface of the deep trench isolation structure produced in the prior art Phenomenon, the surface is not flat, it is easy to cause adverse effects on the subsequent process flow and degrade the performance of the device

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