TECHNICAL FIELD

The present invention relates to a semiconductor device and a method of manufacturing the same, and, more particularly, the present invention relates to a semiconductor device having the lowermost-layer wiring formed as a buried wiring and relates to a method of manufacturing the same.

Along with demands for microfabrication, high integration, and high speed of a semiconductor device, it is required to reduce a wiring resistance, reduce an inter-wiring capacitance, and improve reliability of a wiring. For the reduction of the wiring resistance, a copper (Cu) wiring having a lower resistance than that of a conventional aluminum (Al) alloy is used.

For the reduction of the inter-wiring capacitance, instead of conventional silicon oxide (SiO2), an insulating film having a lower dielectric constant than that of the silicon oxide (hereinafter, which is referred to as a low dielectric constant film) is used as an interlayer insulating film of the wiring.

Japanese Patent Application Laid-Open Publication No. 2004-158832 (Patent Document 1) discloses a technique related to a multilayered wiring using a SiOC film as the low dielectric constant film for the interlayer insulating film.

Meanwhile, in a viewpoint of ensuring reliability of connection between a plug and a wiring, the following techniques are disclosed.

Japanese Patent Application Laid-Open Publication No. 2006-339623 (Patent Document 2) discloses a technique for preventing occurrence of voids upon forming a metal layer 104 by selectively etching an interlayer insulating film 102 so that a surface of the uppermost portion of a contact plug 103 in the lowermost layer is lower than a surface of the uppermost portion of the interlayer insulating film 102, and then, forming the metal layer 104 on the interlayer insulating film 102.

Also, Japanese Patent Application Laid-Open Publication No. 2006-73635 (Patent Document 3) discloses a technique for forming a small upper portion of a contact 7 by processing a conductive material deposited on an interlayer insulating film 6.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2004-158832

Patent Document 2: Japanese Patent Application Laid-Open Publication 2006-339623

Patent Document 3: Japanese Patent Application Laid-Open Publication 2006-73635

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

In recent years, further microfabrication of a semiconductor device has been advanced, and it has been desired to improve performance thereof without various failures.

A preferred aim of the present invention is to improve electric performance of a semiconductor device, and, more particularly, is to reduce delay of a signal transmitted via a wiring.

Also, another preferred aim of the present invention is to improve reliability of a semiconductor device, and, more particularly, is to improve reliability of a wiring.

Further, still another preferred aim of the present invention is to improve electric performance of a semiconductor device and improve reliability of the semiconductor device, and, more particularly, is to reduce delay of a signal transmitted via a wiring and improve reliability of the wiring.

The above and other preferred aims and novel characteristics of the present invention will be apparent from the description of the present specification and the accompanying drawings.

Means for Solving the Problems

The typical ones of the inventions disclosed in the present application will be briefly described as follows.

A method of manufacturing a semiconductor device according to a typical embodiment includes: (a) a step of forming a first interlayer insulating film on a semiconductor substrate; (b) a step of forming a first contact hole in the first interlayer insulating film; and (c) after the step of (b), a step of forming a first conductive film on the semiconductor substrate so as to bury the first conductive film inside the first contact hole. Further, the method includes: (d) a step of removing the first conductive film outside the first contact hole so as to form a first plug made of the first conductive film; (e) after the step of (d), a step of making an upper surface of the first interlayer insulating film to recede so that the upper surface of the first interlayer insulating film is lower than an upper surface of the first plug; and (f) after the step of (e), a step of forming a second interlayer insulating film having a lower dielectric constant than that of silicon oxide, on the semiconductor substrate. Still further, the method includes: (g) a step of forming a first wiring trench in the second interlayer insulating film so that a part of the first plug is exposed and so that a lower surface thereof is lower than an upper surface of the first plug; (h) after the step of (g), a step of forming a second conductive film on the semiconductor substrate so as to bury the second conductive film inside the first wiring trench; and (i) a step of removing the second conductive film outside the first wiring trench so as to form a first wiring made of the second conductive film and connected to the first plug.

Also, a semiconductor device according to a typical embodiment includes: a first interlayer insulating film formed on a semiconductor substrate; a first plug formed inside the first interlayer insulating film; a second interlayer insulating film formed on the first insulating film and having a lower dielectric constant than that of silicon oxide; and a first buried wiring formed inside the second interlayer insulating film and connected to the first plug. And, an upper surface of the first plug is formed at a position higher than an upper surface of the first interlayer insulating film, and a lower surface of the first buried wiring is formed at a position lower than the upper surface of the first plug.

Effects of the Invention

The effects obtained by typical aspects of the present invention disclosed in the present application will be briefly described below.

In a semiconductor device of the present invention, electric performance of the semiconductor device can be improved. More particularly, delay of a signal transmitted via a wiring can be reduced.

Also, effects obtainable by other means will be briefly described below.

In a semiconductor device of the present invention, reliability thereof can be improved. More particularly, reliability of a wiring can be improved.

Further, in a semiconductor device of the present invention, electric performance of the semiconductor device can be improved, and besides, reliability of the semiconductor device can be improved. More particularly, delay of a signal transmitted via a wiring can be reduced, and besides, reliability of a wiring can be improved.

