Abstract: The present disclosure generally relates to a bird's beak profile of a field oxide region. In an example, a semiconductor device structure includes a semiconductor substrate, a dielectric oxide layer, and a field oxide region. The semiconductor substrate has a top surface. The dielectric oxide layer is over the top surface of the semiconductor substrate. The field oxide region is over the semiconductor substrate. The field oxide region is connected to the dielectric oxide layer through a bird's beak region. A lower surface of the bird's beak region interfaces with the semiconductor substrate. In a cross-section along a direction from the field oxide region to the dielectric oxide layer, the lower surface of the bird's beak region does not have a slope with a magnitude that exceeds 0.57735, where rise of the slope is in a direction normal to the top surface of the semiconductor substrate.

Abstract: A method to fabricate a transistor comprises: forming a first dielectric layer on a semiconductor substrate; depositing a barrier layer on the first dielectric layer; depositing an anti-reflective coating on the barrier layer; depositing and exposing a pattern in a photoresist layer to radiation followed by etching to provide an opening; etching a portion of the anti-reflective coating below the opening; etching a portion of the barrier layer below the opening to expose a portion of the first dielectric layer; providing an ambient oxidizing agent to grow an oxide region followed by removing the barrier layer; implanting dopants into the semiconductor substrate after removing the barrier layer; removing the first dielectric layer after implanting dopants into the semiconductor substrate; and forming a second dielectric layer after removing the first dielectric layer, wherein the oxide region is grown to be thicker than the second dielectric layer.

Abstract: A method to fabricate a transistor comprises: forming a first dielectric layer on a semiconductor substrate; depositing a barrier layer on the first dielectric layer; depositing an anti-reflective coating on the barrier layer; depositing and exposing a pattern in a photoresist layer to radiation followed by etching to provide an opening; etching a portion of the anti-reflective coating below the opening; etching a portion of the barrier layer below the opening to expose a portion of the first dielectric layer; providing an ambient oxidizing agent to grow an oxide region followed by removing the barrier layer; implanting dopants into the semiconductor substrate after removing the barrier layer; removing the first dielectric layer after implanting dopants into the semiconductor substrate; and forming a second dielectric layer after removing the first dielectric layer, wherein the oxide region is grown to be thicker than the second dielectric layer.