Method for reducing depressed deformation of sacrificial layer in three-dimensional stacking in chemical mechanical polishing

The invention relates to a method for reducing depressed deformation of a sacrificial layer in three-dimensional stacking in chemical mechanical polishing. The method includes the steps of firstly, growing a stop layer; secondly, etching the stop layer to form an etching trench; thirdly, depositing the sacrificial layer; fourthly, etching the sacrificial layer; fifthly, depositing a planarization layer; sixthly, conducting wafer non-graphical etching; seventhly, removing the sacrificial layer and the planarization layer; eighthly, removing the stop layer; ninthly, adjusting flatness and roughness of a wafer through chemico-mechanical polishing; tenthly, cleaning after grinding. The method has the advantages that since the photoetched sacrificial layer and planarization material filling are added, surface morphological unevenness caused by graphics with huge differences in size and density is removed and the super-thick sacrificial layer CMP cost is reduced greatly; ultra-high planarization uniformity and little depressed deformation can be achieved through non-graphical etching and three-step CMP, so that the planarization requirements on different thicknesses of silicon dioxide sacrificial layers in three-dimensional stacking are met.