US 7,064,072 B1Granted

Method for fabricating trench isolation

AssigneeUnited Microelectronics Corp.

InventorsWei-Chi Ting, Jen-Yuan Wu

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Abstract

A semiconductor substrate having a front surface and a backside is prepared. A first silicon oxide layer is formed on the front surface of the semiconductor substrate and, simultaneously, forming a second silicon oxide layer on the backside of the semiconductor substrate. A first silicon nitride layer is formed on the front surface of the semiconductor substrate and, simultaneously, forming a second silicon nitride layer on the backside of the semiconductor substrate. Lithographic and etching process is performed, using the first silicon nitride layer as an etching hard mask, to etch a trench into the front surface of the semiconductor substrate. The trench is then filled with insulating material. Using the insulating material as an etching hard mask, the second silicon nitride layer on the backside of the semiconductor substrate is etched away. A densification process is then performed to densify the insulating material.

Claims5

Dependent claims

A method for fabricating trench isolation, comprising:

providing a semiconductor substrate having a front surface and a backside;
forming a first silicon oxide layer on the front surface of the semiconductor substrate and, simultaneously, forming a second silicon oxide layer on the backside of the semiconductor substrate;
forming a first silicon nitride layer on the front surface of the semiconductor substrate and, simultaneously, forming a second silicon nitride layer on the backside of the semiconductor substrate;
performing lithographic and etching process and using the first silicon nitride layer as an etching hard mask to etch a trench into the front surface of the semiconductor substrate;
filling the trench with insulating material, the insulating material also covering the first silicon nitride layer;
using the insulating material as an etching hard mask and etching away the second silicon nitride layer on the backside of the semiconductor substrate;
performing a densification process to densify the insulating material;
and
performing a chemical mechanical polishing process and using the first silicon nitride layer as a polish stop to planarize the insulating material.

6 more elements

Dependencies are inferred from the claim text.