Semiconductor structure having front side and back side and method of forming same

Abstract

A method includes providing a structure having a transistor, an isolation structure over the transistor, two metal plugs passing through the isolation structure and electrically connected to the transistor, and a trench having the isolation structure and the metal plugs as sidewalls. The method further includes forming a dielectric liner on sidewalls of the trench and over the isolation structure and the metal plug. The dielectric liner is thinner at an opening portion of the trench than at another portion of the trench, thereby forming an air gap inside the trench, and the air gap is surrounded by the dielectric liner. The method further includes depositing a sacrificial layer over the dielectric liner and over the air gap, and performing CMP to remove the sacrificial layer and recess the dielectric liner until the isolation structure and the metal plug are exposed. The air gap remains inside the trench.

Description

technical field [0001] Embodiments of the present application relate to semiconductor structures having front sides and back sides and methods of forming the same. Background technique [0002] The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced several generations of ICs, each smaller and more complex than the previous generation. During the development of ICs, functional density (ie, the number of interconnected devices per chip area) has generally increased, while its geometric size (ie, the smallest component (or circuit) that can be manufactured using a manufacturing process) has decreased. This scaling down process often brings the benefits of increased production efficiency and lower associated costs. This scaling down also increases the complexity of IC processing and manufacturing. Therefore, semiconductor manufacturing processes need to be continuously improved. O...

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Problems solved by technology

However, as semiconductor technology advances to smaller geometries, the distance between metal parts is further reduced, which increases stray capacitance

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