Semiconductor device and manufacturing method of the same

Abstract

The reliability of a semiconductor device having an embedded wire in the lowest layer wire is improved. In a main surface of a semiconductor substrate, MISFETs are formed and over the main surface, insulating films 10, 11 are formed. In the insulating films 10, 11 a contact hole is formed and a plug is embedded therein. Over the insulating film 11 in which the plug is embedded, insulating films 14, 15, 16 are formed and an opening is formed in the insulating films 14, 15, 16 and a wire is embedded therein. The insulating film 15 is an etching stopper film when etching the insulating film 16 in order to form the opening, containing silicon and carbon. The insulating film 11 has a high hygroscopicity and the insulating film 15 has a low moisture resistance, however, by interposing the insulating film 14 therebetween and making the insulating film 14 have a higher density of the number of Si (silicon) atoms than that of the insulating film 11 , an electrically weak interface is prevented from being formed.

1 . A semiconductor device comprising:
 a semiconductor substrate;   a semiconductor element formed in a main surface of the semiconductor substrate;   a first insulating film containing silicon and oxygen formed over the main surface in which the semiconductor element of the semiconductor substrate is formed;   a first opening formed in the first insulating film;   a first conductor part embedded in the first opening;   a second insulating film containing silicon and oxygen formed over the first insulating film;   a third insulating film containing silicon and carbon formed over the second insulating film;   a fourth insulating film containing silicon and oxygen formed over the third insulating film;   a wire opening formed in the second, third, and fourth insulating films and which exposes at least part of the first conductor part at the bottom thereof; and   a first wire embedded in the wire opening and electrically coupled with the first conductor part,   wherein the second insulating film is a film with a higher density of the number of Si atoms than that of the first insulating film.   
     
     
         2 . The semiconductor device according to  claim 1 ,
 wherein the second insulating film is an insulating film formed by the plasma CVD method; and   wherein the first insulating film is not an insulating film formed by the plasma CVD method.   
     
     
         3 . The semiconductor device according to  claim 2 ,
 wherein the first insulating film is an insulating film formed by the thermal CVD method or coating method.   
     
     
         4 . The semiconductor device according to  claim 1 ,
 wherein the first and second insulating films contain silicon and oxygen as principal components.   
     
     
         5 . The semiconductor device according to  claim 1 ,
 wherein the first insulating film is a silicon oxide film; and   wherein the second insulating film is a silicon oxide film or a silicon oxynitride film.   
     
     
         6 . The semiconductor device according to  claim 1 ,
 wherein the first insulating film is an O 3 -TEOS oxide film or an SOG film.   
     
     
         7 . The semiconductor device according to  claim 1 ,
 wherein the etching rate by hydrofluoric acid is lower in the second insulating film than in the first insulating film.   
     
     
         8 . The semiconductor device according to  claim 1 ,
 wherein the third insulating film is an etching stopper film when etching the fourth insulating film in order to form the wire opening.   
     
     
         9 . The semiconductor device according to  claim 1 ,
 wherein the third insulating film is a SiC film, a SiCN film, or a SiCO film.   
     
     
         10 . The semiconductor device according to  claim 1 ,
 wherein the fourth insulating film is a silicon oxide film, a silicon oxynitride film, or an insulating film with a dielectric constant lower than that of a silicon oxide film.   
     
     
         11 . The semiconductor device according to  claim 1 ,
 wherein the third insulating film has an oxygen content lower than a silicon content.   
     
     
         12 . The semiconductor device according to  claim 11 ,
 wherein the fourth insulating film has an oxygen content not lower than a silicon content.   
     
     
         13 . The semiconductor device according to  claim 1 ,
 wherein the fourth insulating film has a dielectric constant lower than that of the third insulating film.   
     
     
         14 . The semiconductor device according to  claim 1 ,
 wherein the fourth insulating film contains silicon, oxygen, and nitrogen.   
     
     
         15 . The semiconductor device according to  claim 1 ,
 wherein the film thickness of the fourth insulating film is larger than that of the second insulating film and larger than that of the third insulating film.   
     
     
         16 . The semiconductor device according to  claim 1 ,
 wherein the first opening is formed in the first insulating film but not in the second insulating film.   
     
     
         17 . The semiconductor device according to  claim 1 ,
 wherein the semiconductor element includes an MISFET; and   wherein the first insulating film is formed over the main surface of the semiconductor substrate so that a gap between gate electrodes of the MISFET is filled therewith.   
     
     
         18 . The semiconductor device according to  claim 1 ,
 wherein the semiconductor element includes an MISFET; and   wherein a nickel silicide layer is formed over the top surface of a semiconductor region for the source or drain constituting the MISFET or over the top surface of the gate electrode.   
     
     
         19 . The semiconductor device according to  claim 1 ,
 wherein a plurality of wire layers is formed over the semiconductor substrate; and   wherein the first wire includes a wire layer in the lowest layer among the wire layers.   
     
     
         20 . The semiconductor device according to  claim 1 ,
 wherein the first conductor part does not contain copper; and   wherein the second insulating film includes a silicon oxide film.   
     
     
         21 . The semiconductor device according to  claim 1 , wherein the first conductor part contains copper; and
 wherein the second insulating film includes a silicon oxynitride film.   
     
     
         22 . The semiconductor device according to  claim 1 ,
 wherein a part of the top surface of the first conductor part is in contact with the first wire and another part thereof is covered with the second insulating film.   
     
     
         23 . The semiconductor device according to  claim 1 , further comprising:
 a fifth insulating film including a material different from that of the first insulating film formed over the main surface in which the semiconductor element of the semiconductor substrate is formed,   wherein the first insulating film is formed over the fifth insulating film; and   wherein the first opening is formed in a laminated film including the first and fifth insulating films.   
     
     
         24 . The semiconductor device according to  claim 1 ,
 wherein a first laminated film including the first insulating film and a sixth insulating film formed partially over the top of the first insulating film is formed over the main surface of the semiconductor substrate;   wherein the top surface of the first laminated film is flattened;   wherein the first insulating film is exposed partially in the flattened top surface of the first laminated film;   wherein the first opening is formed in the first laminated film; and   wherein the second insulating film is formed over the first laminated film.   
     
     
         25 . The semiconductor device according to  claim 24 ,
 wherein the first insulating film neighbors the top surface of the first conductor part.   
     
     
         26 . A manufacturing method of a semiconductor device comprising the steps of:
 (a) preparing a semiconductor substrate;   (b) forming a semiconductor element in the main surface of the semiconductor substrate;   (c) forming a first insulating film containing silicon and oxygen over the main surface in which the semiconductor element of the semiconductor substrate is formed;   (d) forming a first opening in the first insulating film;   (e) forming a first conductor part embedded in the first opening;   (f) forming a second insulating film containing silicon and oxygen over the first insulating film in which the first conductor part is embedded;   (g) forming a third insulating film containing silicon and oxygen over the second insulating film;   (h) forming a fourth insulating film containing silicon and oxygen over the third insulating film;   (i) forming a wire opening in the fourth insulating film by etching the fourth insulating film;   (j) exposing at least part of the top surface of the first conductor part at the bottom of the wire opening by etching the third insulating film and the second insulating film at the bottom of the wire opening; and   (k) forming a first wire embedded in the wire opening and electrically coupled with the first conductor part,   wherein the second insulating film is a film with a higher density of the number of Si atoms than that of the first insulating film.   
     
     
         27 . The manufacturing method of a semiconductor device according to  claim 26 ,
 wherein in the (i) step, a wire opening is formed in the fourth insulating film by etching the fourth insulating film using the third insulating film as an etching stopper.   
     
     
         28 . The manufacturing method of a semiconductor device according to  claim 27 ,
 wherein in the (c) step, the first insulating film is formed using the thermal CVD method or coating method; and   wherein in the (f) step, the second insulating film is formed using the plasma CVD method.   
     
     
         29 . The manufacturing method of a semiconductor device according to  claim 28 ,
 wherein the first insulating film is an O 3 -TEOS oxide film or an SOG film;   wherein the second insulating film is a silicon oxide film or a silicon oxynitride film;   wherein the third insulating film is a SiC film, a SiCN film, or a SiCO film; and   wherein the fourth insulating film is a silicon oxide film, a silicon oxynitride film, or an insulating film with a lower dielectric constant than that of a silicon oxide film.   
     
     
         30 . The manufacturing method of a semiconductor device according to  claim 28 ,
 wherein the first wire is a wire layer in the lowest layer among the wire layers formed over the semiconductor substrate.   
     
     
         31 . The manufacturing method of a semiconductor device according to  claim 28 ,
 wherein the top surface of the first insulating film formed in the (c) step is not flat;   wherein after the (c) step and before the (d) step, the method further comprises the steps of:   (c1) forming a sixth insulating film over the first insulating film; and   (c2) flattening a top surface of a first laminated film including the first and sixth insulating films by polishing and partially exposing the first insulating film in the top surface of the flattened first laminated film;   wherein in the (d) step, the first opening is formed in the first laminated film; and   wherein in the (f) step, the second insulating film is formed over the first laminated film in which the first conductor part is embedded.   
     
     
         32 . The manufacturing method of a semiconductor device according to  claim 31 ,
 wherein in the (d) step, the first opening is formed at a position that overlaps with the part of the top surface of the first laminated film where the first insulating film is exposed.