Methods of forming trench isolation in the fabrication of integrated circuitry and methods of fabricating integrated circuitry

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 which is less than that of the second isolation trench, the first isolation trench having a largest aspect ratio of at least 25;
• depositing an insulative layer to within the first and second isolation trenches effective to fill remaining volume of the first isolation trench within the semiconductive material but not that of the second isolation trench within the semiconductive material, the insulative layer comprising silicon dioxide deposited from flowing TEOS to the first and second isolation trenches;
• depositing a spin-on-dielectric over the silicon dioxide deposited from flowing the TEOS within the second isolation trench within the semiconductive material, but not within the first isolation trench within the semiconductive material;
• the spin-on-dielectric being deposited effective to fill remaining volume of the second isolation trench within the semiconductive material;
• and
• densifying the spin-on-dielectric within the second isolation trench.

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 which is less than that of the second isolation trench;
• depositing an insulative layer to within the first and second isolation trenches effective to fill remaining volume of the first isolation trench within the semiconductive material but not that of the second isolation trench within the semiconductive material, the insulative layer comprising silicon dioxide deposited from flowing TEOS to the first and second isolation trenches;
• depositing a spin-on-dielectric over the silicon dioxide deposited from flowing the TEOS within the second isolation trench within the semiconductive material, but not within the first isolation trench within the semiconductive material;
• the spin-on-dielectric being deposited effective to fill remaining volume of the second isolation trench within the semiconductive material, the spin-on-dielectric being deposited over the semiconductor substrate laterally outward of the first and second isolation trenches to a thickness no greater than 4,500 Angstroms;
• and
• densifying the spin-on-dielectric within the second isolation trench.

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 which is less than that of the second isolation trench;
• depositing an insulative layer to within the first and second isolation trenches effective to fill remaining volume of the first isolation trench within the semiconductive material but not that of the second isolation trench within the semiconductive material, the insulative layer comprising silicon dioxide deposited from flowing TEOS to the first and second isolation trenches and having a seam extending at least partially into the first isolation trench;
• depositing a spin-on-dielectric over the silicon dioxide deposited from flowing the TEOS within the second isolation trench within the semiconductive material, but not within the first isolation trench within the semiconductive material;
• the spin-on-dielectric being deposited effective to fill remaining volume of the second isolation trench within the semiconductive material;
• and
• densifying the spin-on-dielectric within the second isolation trench and effective to remove the seam formed in the insulative layer comprising silicon dioxide in the first isolation trench.

A method of forming integrated circuitry, comprising:

• forming isolation trenches within semiconductive material of a first area of circuitry of a semiconductor substrate and within semiconductive material of a second area of circuitry of the semiconductor substrate, the first circuitry area comprising a first minimum active area spacing between the isolation trenches received therein and the second circuitry area comprising a second minimum active area spacing between the isolation trenches received therein, the first minimum active area spacing being less than the second minimum active area spacing, the isolation trenches within the first circuitry area having respective narrowest outermost cross sectional dimensions which are less than that of the isolation trenches within the second circuitry area, the isolation trenches within the first circuitry area having respective largest aspect ratios of at least 25;
• depositing an insulative layer to within the isolation trenches of the first circuitry area and to within the isolation trenches of the second circuitry area, the insulative layer comprising silicon dioxide deposited from flowing TEOS to the isolation trenches within the first and second circuitry areas, the insulative layer less than filling remaining volume of the isolation trenches within the semiconductive material of the second circuitry area, the depositing of the insulative layer being effective to fill remaining volume of the isolation trenches within the first circuitry area;
• and
• after depositing the insulative layer, depositing a spin-on-dielectric over the silicon dioxide deposited from flowing the TEOS within the isolation trenches within the first circuitry area, but not within the isolation trenches within the second circuitry area;
• the spin-on-dielectric being deposited effective to fill remaining volume of the isolation trenches within the second circuitry area;
• and
• densifying the spin-on-dielectric within the isolation trenches in the second circuitry area.