Copper interconnect structure and method for manufacturing the same

摘要

A method is disclosed for manufacturing a semiconductor device with a copper interconnect structure. The method includes providing a substrate, forming a first interconnect dielectric layer on the substrate, and forming a second interconnect dielectric layer on a surface of the first interconnect dielectric layer. The method also includes forming a plurality of conduits extending through the first interconnect dielectric layer and the second interconnect dielectric layer, and depositing copper in the plurality of conduits to form a copper interconnect layer of the copper interconnect structure. Further, the first interconnect dielectric layer, between neighboring conduits, contains cavities such that dielectric constant of the first interconnect dielectric layer is reduced. The second interconnect dielectric layer seals the top of the cavities, the substrate is the bottom of the cavities, and a width of the top of the cavities is less than a width of the bottom of the cavities.

主权项

1. A method for manufacturing a semiconductor device with a copper interconnect structure, comprising:
providing a substrate; forming a sacrificial layer on the substrate; forming a photoresist layer on the sacrificial layer; forming a plurality of first windows in the photoresist layer by photolithography using a first mask; forming a plurality of first openings in the sacrificial layer by an etching process using the first windows as a mask; forming a plurality of second windows in the photoresist layer corresponding to the plurality of first windows, wherein a width of each of the second windows is greater than a width of the corresponding first window such that a portion of the sacrificial layer is exposed in the second windows; forming a plurality of second openings by an etching process using the second window as a mask such that the top portion of each of the second openings is in a shape of an inverted trapezoid; removing the photoresist layer; depositing a layer of dielectric material on the sacrificial layer and in the second openings; and forming the first interconnect dielectric layer by removing the deposited layer of dielectric material using a chemical mechanical polishing (CMP) process until a tip of the sacrificial layer between two second openings is also removed to form a releasing opening; removing the sacrificial layer to form cavities with corresponding releasing openings as the top of the cavities; depositing a second interconnect dielectric layer on the first interconnect dielectric layer such that the second interconnect dielectric layer seals the releasing openings without filling the cavities; forming a second photoresist layer on the second interconnect dielectric layer; forming a plurality of third windows in the second photoresist layer by photolithography using the first mask such that the third windows have a smaller window width than the first windows; and forming a plurality of conduits in the first interconnect dielectric layer and the second interconnect dielectric layer by an etching process using the third windows as a mask such that the cavities are maintained in the first interconnect dielectric layer; and depositing copper in the plurality of conduits to form a copper interconnect layer of the copper interconnect structure, wherein: the first interconnect dielectric layer, between neighboring conduits, contains the plurality of cavities each in a shape of a combination of a trapezoid and a rectangle such that dielectric constant of the first interconnect dielectric layer is reduced; the second interconnect dielectric layer seals the top of the cavities; the substrate forms a bottom surface of the cavities; and a width of the top of the cavities is less than a width of the bottom of the cavities; an upper portion of each cavity is in a shape of a trapezoid; a lower portion of each cavity is in a shape of a rectangle.