At&t Ipm Corp.

Kenenth G Moerschel

Janmye Sung

Tzu-Yin Chiu

Frank M Erceg

Te-Yin M Liu

Michael Allen Prozonic

An integrated circuit fabrication process for creating field oxide regions in a substrate is disclosed. In the process, masking layers of oxide, nitride and deposited silicon dioxide are formed on the substrate. A pattern that defines the field oxide regions in the substrate is introduced into the substrate through these masking layers. The field oxide region is bordered by steep sidewalls in a portion of the substrate and the masking layers overlying the substrate. A thin layer of oxide is grown on the exposed portion of the substrate, and a conformal second layer of nitride followed by a conformal layer of a polycrystalline material are formed over the substrate/mask structure. The polycrystalline layer is selectively removed, so that the only portion of the polycrystalline material that remains on the structure is the portion covering the sidewalls. The exposed portions of the second nitride layer are then removed, leaving only those portions of the second nitride layer that are interposed between the polycrystalline material and the sidewalls on the substrate surface. The remaining portions of the polycrystalline material on the surface of the structure are then removed. The field oxide is then grown on the field oxide region of the substrate. The portions of the second nitride layer on the sidewalls are lifted and bent as the oxide is grown. The lifting and bending of the second nitride layer forms grooves in the field oxide as it is grown. The remaining layers of the mask are then removed. A thin layer of oxide is then grown or deposited on the surface of the substrate. A layer of nitride with a thickness that is at least one-half the width of the grooves in the field oxide is deposited on the substrate surface. The nitride layer is then removed except for that portion of the nitride in the grooves.

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Bethlehem, PA, United States of America

Kenenth G Moerschel