A wafer back sealing structure and its manufacturing method

Abstract

The present invention proposes a wafer back seal structure and its manufacturing method, comprising: providing a substrate, the substrate has a first surface and a second surface opposite to each other; forming an epitaxial layer on the first surface; forming The stacked structure is on the epitaxial layer and the second surface; wherein, the stacked structure includes a first oxide layer, a polysilicon layer, and a second oxide layer; the epitaxial layer is removed by dry etching the second oxide layer to expose the polysilicon layer on the first surface; remove the polysilicon layer on the epitaxial layer by wet etching to expose the polysilicon layer on the first surface the first oxide layer on the surface; removing the first oxide layer on the epitaxial layer by wet etching, and removing the second oxide layer on the second surface. The manufacturing method of the wafer back sealing structure proposed by the present invention is simple in process.

Description

Technical field[0001]The invention relates to the field of semiconductors, in particular to a wafer back sealing structure and a manufacturing method thereof.Background technique[0002]At present, epitaxially deposited silicon wafers such as image sensors and power devices are heavily doped substrates. In order to prevent the escape of dopants and high-temperature self-doping, a back seal material is deposited on the back of the wafer, and then the surface of the silicon substrate is polished And epitaxial layer (EPI). However, before the subsequent process, it is necessary to polish and clean the silicon substrate on which the back seal material film and the epitaxial layer are grown, or perform the rework cleaning of the pad silicon dioxide and silicon nitride on the active area. The high corrosion rate of the layer will cause damage to the back seal material film. At the same time, in the subsequent process, the back seal material film may be completely removed, resulting in the p...

AI Technical Summary

Problems solved by technology

However, before the subsequent process, it is necessary to polish and clean the silicon substrate on which the back-sealing material film and epitaxial layer are grown, or to rework and clean the pad layer of silicon dioxide and silicon nitride in the active area. The high corrosion rate of the layer will cause damage to the back-sealing material film. At the same time, in the subsequent process, the back-sealing material film may be completely removed, resulting in the precipitation of heavily doped ions on the substrate and causing cross-contamination; It will affect the performance of the subsequent test, and the difference of the back seal may affect the load effect of the furnace tube and the back temperature detection of the thermal annealing process

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