Semiconductor isolation structure with air gaps in deep trenches

摘要

A device includes a semiconductor substrate, a contact plug over the semiconductor substrate, and an Inter-Layer Dielectric (ILD) layer over the semiconductor substrate, with the contact plug being disposed in the ILD. An air gap is sealed by a portion of the ILD and the semiconductor substrate. The air gap forms a full air gap ring encircling a portion of the semiconductor substrate.

主权项

1. A device comprising:
a semiconductor substrate; a first Metal-Oxide-Semiconductor (MOS) device at a top surface of the semiconductor substrate; a second MOS device at the top surface of the semiconductor substrate; a first trench extending into the semiconductor substrate from the top surface of the semiconductor substrate, the first trench including a first portion, a second portion, and a third portion, wherein:
the first portion of the first trench surrounds the first MOS device and the second MOS device,the second portion of the first trench extends between the first MOS device and the second MOS device, the second portion of the first trench being contiguous with the first portion of the first trench, andthe third portion of the first trench extends between the first MOS device and the second MOS device, the third portion of the first trench being contiguous with the first portion of the first trench, the second portion of the first trench being separated from the third portion of the first trench in a direction from the first MOS device to the second MOS device by a portion of the semiconductor substrate; an Inter-Layer Dielectric (ILD) layer over the semiconductor substrate and extending into the first trench, wherein a first air gap is sealed in the first trench by the ILD layer, wherein at least a portion of the first air gap is disposed in the first trench below the top surface of the semiconductor substrate, wherein the semiconductor substrate along a first semiconductor sidewall of the first trench contacts the first air gap, and wherein the first air gap is contiguous through the first portion of the first trench, the second portion of the first trench, and the third portion of the first trench; and a contact plug through the ILD and connected to at least one of the first MOS device and the second MOS device.