Patent ID: 8012847

Claim:
A method of forming trench isolation in the fabrication of integrated circuitry, comprising: forming first and second isolation trenches into semiconductive material of a semiconductor substrate, the first isolation trench having a narrowest outermost cross sectional dimension within the semiconductive material which is less than that of the second isolation trench, the second isolation trench comprising a planar base surface of the semiconductive material, the semiconductive material comprising a planar outermost surface adjacent the second isolation trench; depositing an insulative layer to within the first and second isolation trenches effective to fill remaining volume of that portion of the first isolation trench which is received within the semiconductive material but not that portion of the second isolation trench which is received within the semiconductive material, an outermost portion of the insulative layer comprising silicon dioxide deposited from flowing TEOS to the first and second isolation trenches and having a seam within the silicon dioxide that extends at least partially into that portion of the first isolation trench which is received within the semiconductive material, the insulative layer comprising a planar outer surface received within that portion of the second isolation trench which is received within the semiconductive material, said planar outer surface of the insulative layer being elevationally closer to the planar base surface of the semiconductive material than to the planar outermost surface of the semiconductive material adjacent the second isolation trench; depositing a spin-on-dielectric comprising polysilazane in direct physical touching contact with the outermost portion of that portion of the silicon dioxide deposited from flowing the TEOS within the second isolation trench which is received within the semiconductive material, but not within that portion of the first isolation trench which is received within the semiconductive material; the spin-on-dielectric being deposited effective to fill remaining volume of that portion of the second isolation trench which is received within the semiconductive material; densifying the spin-on-dielectric which is received within that portion of the second isolation trench which is received within the semiconductive material to remove the seam formed in the silicon dioxide in the first isolation trench, the densifying comprising a heat treatment in an O 2 ambient followed by steam exposure and subsequent drying in O 2 ; and planarizing by removing outermost portions of the spin-on-dielectric and the silicon dioxide thereby exposing the planar outermost surface adjacent the second isolation trench and a planar outermost surface of semiconductive material adjacent the first isolation trench.