Patent ID: 8828877

Claim:
A process for forming a shallow trench isolation structure, comprising the steps of: coating a composition containing insulating material onto a substrate surface provided with a trench structure, to form a coating layer; firing the coated substrate to harden the insulating material, so as to form an insulating layer; polishing the insulating layer so as to remove the part formed on the flat surface of the substrate and to leave the part formed in the trenches on the substrate and subjecting the insulating layer after polished to etching treatment by use of an etching solution containing hydrofluoric acid and an organic solvent, wherein said hydrofluoric acid is contained in an amount of 0.06 to 2 wt % based on the total weight of the solution, and wherein said organic solvent has a δH value defined by Hansen solubility parameters in the range of 4 to 12 inclusive and the saturation solubility thereof in water is 5 wt % or more at 20° C. and wherein said insulating material is a polysilazane compound and said insulating layer is a siliceous film and further wherein the etching solution removes evenly the insulating layer by etching where the widths of the trenches are different from each other.