Semiconductor structure comprising an air chamber and method of manufacturing the same

A semiconductor structure, wherein the semiconductor structure comprises:

• a base, wherein the base comprises an active region and a shallow trench isolation structure separating the active region;
• a word line trench, wherein the word line trench is formed in the base and intersects the active region and the shallow trench isolation structure;
• and
• a word line structure, wherein the word line structure is formed in the word line trench, the word line structure comprises a conductive layer, a top isolation structure, and an air chamber, and the air chamber is arranged between the conductive layer and the top isolation structure;
• wherein the word line structure further comprises a gate dielectric layer and a first isolation structure, the gate dielectric layer covers a bottom wall and side walls of the word line trench, the first isolation structure covers a top surface of the conductive layer and a part of side walls of the gate dielectric layer, and an air layer is provided between the top isolation structure and the first isolation structure;
• wherein the top isolation structure comprises a second isolation structure and a third isolation structure, and a bottom surface of the third isolation structure is equal to or higher than a bottom surface of the second isolation structure;
• and
• wherein the word line structure further comprises a sacrificial structure, the sacrificial structure covers side walls of the first isolation structure, and the second isolation structure covers side walls of the sacrificial structure.