Wafer back sealing structure and manufacturing method thereof

Abstract

The invention provides a wafer back sealing structure and a manufacturing method thereof, and the method comprises the steps: providing a substrate which is provided with a first surface and a secondsurface, forming an epitaxial layer on the first surface; forming a laminated structure on the epitaxial layer and the second surface, wherein the laminated structure comprises a first oxide layer, apolycrystalline silicon layer and a second oxide layer; removing the second oxide layer on the epitaxial layer through dry etching so as to expose the polycrystalline silicon layer on the first surface; removing the polycrystalline silicon layer on the epitaxial layer through wet etching so as to expose the first oxide layer on the first surface; and removing the first oxide layer on the epitaxiallayer through wet etching, and removing the second oxide layer on the second surface. The manufacturing method of the wafer back sealing structure provided by the 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 dopant escape and high temperature self-doping, a back-sealing material is deposited on the back of the wafer, and then the silicon substrate is surface polished And the epitaxial layer (EPI). 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. Due to the low-temperature oxidation of the back-sealing 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...

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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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