| CPC H10D 62/116 (2025.01) [H01L 21/76224 (2013.01); H10D 30/0281 (2025.01); H10D 30/65 (2025.01)] | 19 Claims |

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1. An integrated circuit (IC) structure, comprising:
a trench isolation (TI) in a substrate, the TI including:
a lower portion including a first dielectric material and having a first width;
a middle portion including the first dielectric material and an outer second dielectric material; and
an upper portion including a third dielectric material and having a second width greater than the first width,
wherein the first, second and third dielectric materials are different,
wherein the third dielectric material contacts the first dielectric layer at a first portion of a material interface and the second dielectric material at a second portion of the material interface, and the third dielectric material has an uppermost surface coplanar with an uppermost surface of the substrate.
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