Integration sequences with top surface profile modification

A method for processing a substrate, comprising:

• forming a trench structure through a layer of polycrystalline silicon;
• filling the trench structure with silicon oxide;
• planarizing the substrate to expose the layer of polycrystalline silicon on a surface of the substrate;
• etching back the silicon oxide to in the trench structure to form a recess in the trench structure;
• and
• rounding bottom corners of the recess comprising:
• depositing a conformal layer of silicon oxide over the surface of the substrate, and sidewalls and bottom of the recess;
• and
• removing the conformal layer of silicon oxide to expose the layer of polycrystalline silicon on the surface of the substrate.

A method for processing a substrate, comprising:

• depositing a first polycrystalline silicon layer on a first insulative layer disposed on a silicon substrate;
• forming trench structures through the first polycrystalline silicon layer and the first insulative layer and into the silicon substrate;
• depositing a silicon oxide material over the first polycrystalline silicon layer while filling the trench structures with the silicon oxide material;
• planarizing and removing a portion of the silicon oxide material to expose the first polycrystalline silicon layer;
• forming recesses having rounded bottom corners within the silicon oxide material disposed in the trench structure;
• and
• depositing a second polycrystalline silicon layer over the first polycrystalline silicon layer while filling the recesses with rounded bottoms,
• wherein forming the recesses having rounded bottom corners comprises:
• etching a first portion of the silicon oxide material to form recesses having sharp bottom corners within the silicon oxide material disposed in the trench structures;
• depositing a conformal silicon oxide layer on the recesses with sharp bottom corners;
• and
• removing the conformal silicon oxide layer and etching a second portion of the silicon oxide material to form the recesses with rounded bottom corners.