Semiconductor device have multiple wiring layers and method of producing the same

Abstract

A semiconductor device having a plurality of wiring layers includes: a first insulating film firstly formed in layer; a first wiring layer having a plurality of wirings, formed on the first insulating film; a second wiring layer having a plurality of wirings, formed on or over the first wiring layer; and a second insulating film provided on the first insulating film formed as having a plane surface and the first wiring layer, and formed between adjacent wirings of the second wiring layer, located under the second wiring layer but on the first insulating film and the first wiring layer, at least a part of the second insulating film existing between the first and second wiring layers having a relative dielectric constant lower than a relative dielectric constant of the first insulating film. A method of producing a semiconductor device having a plurality of wiring layers forms a first interlayer-insulating film, forms a plurality of grooves for wiring in the first interlayer-insulating film, fills metallic films in the groves to form wirings, etches the first interlayer-insulating film with the wirings as a mask and removes the interlayer-insulating film between the wirings to provide groves to be filled, and fills a second interlayer-insulating film made of a material of low dielectric constant in the groves to be filled.

What is claimed is:  
     
         1 . A semiconductor device having a plurality of wiring layers, comprising: 
 a semiconductor substrate;    a first insulating film formed on the semiconductor substrate;    a first wiring layer formed to be buried in the first insulating film so as to have a surface being substantially coplanar with a surface of the first insulating layer;    a second insulating film provided on the first insulating film and the first wiring layer; and    a second wiring layer formed to be buried in the second insulating film so as to have a surface being substantially coplanar with a surface of the second insulating layer,    wherein a relative dielectric constant of a part existing between two adjacent wirings of the second wiring layer, is lower than a relative dielectric constant of the first insulating film.    
     
     
         2 . A semiconductor device having a plurality of wiring layers comprising: 
 a semiconductor substrate;    a first insulating film formed on the semiconductor substrate;    a second wiring layer having a plurality of wirings, formed on or over the first wiring layer; and    a second insulating film provided on the first insulating film formed as having a plane surface and the first wiring layer, and formed between adjacent wirings of the second wiring layer, located under the second wiring layer but on the first insulating film and the first wiring layer, at least a part of the second insulating film existing between the first and second wiring layers having a relative dielectric constant lower than a relative dielectric constant of the first insulating film.    
     
     
         3 . The semiconductor device according to  claim 2 , wherein the second insulating film is made of at least an organic material-applied insulating film or a porous insulating film made of a material selected from the group consisting of resin having siloxane bonding as a major structure, resin having C—C bonding as a major structure and a resin having C═C bonding as a major structure.  
     
     
         4 . The semiconductor device according to  claim 2 , wherein the second insulating film has a relative dielectric constant of 2.5 or smaller.  
     
     
         5 . The semiconductor device according to  claim 2  further comprising: 
 a plug connecting several wirings of the first and second wiring layers, formed in the second insulating film; and  
 a low-dielectric-constant insulating film formed between the wirings of the second wiring layer and between the second wiring layer and the second insulating film or the plug, the low-dielectric-constant insulating film having a relative dielectric constant lower than a relative dielectric constant of the second insulating film.  
 
     
     
         6 . The semiconductor device according to  claim 5 , wherein the low-dielectric-constant insulating film is made of at least an organic-applied insulating film or a porous insulating film made of a material selected from the group consisting of resin having siloxane bonding as a major structure, resin having C—C bonding as a major structure and a resin having C═C bonding as a major structure.  
     
     
         7 . The semiconductor device according to  claim 5 , wherein the low-dielectric-constant insulating film has a relative dielectric constant of 2.5 or smaller.  
     
     
         8 . The semiconductor device according to  claim 5  further comprising a barrier film between the second and low-dielectric -constant insulating films.  
     
     
         9 . The semiconductor device according to  claim 2  further comprising a cap layer to protect the wirings from damages due to etching, provided on at least the wirings constituting the second wiring layer among the wirings of the first and second wiring layers.  
     
     
         10 . The semiconductor device according to  claim 9 , wherein the cap layer is buried in the second insulating layer together with the second wiring layer.  
     
     
         11 . The semiconductor device according to  claim 9 , further comprising: 
 a plug connecting several wirings of the first and second wiring layers, formed in the second insulating film; and    a low-dielectric-constant insulating film formed between the wirings of the second wiring layer and between the second wiring layer and the second insulating film or the plug, the low-dielectric-constant insulating film having a relative dielectric constant lower than a relative dielectric constant of the second insulating film.    
     
     
         12 . The semiconductor device according to  claim 2  further comprising: 
 an (n−1)-th wiring layer having a plurality of wirings, formed on or over the second wiring layer, n being an integer of 4 or more;  
 an (n−1)-th insulating film provided on or over the second insulating film formed as having a plane surface and the second wiring layer, and formed between adjacent wirings of the (n−1)-th wiring layer, located under the (n−1)-th wiring layer but over the second insulating film and the second wiring layer, at least a part of the (n−1)-th insulating film existing between the second and (n−1)-th wiring layers having a relative dielectric constant lower than a relative dielectric constant of the second insulating film;  
 an n-th wiring layer having a plurality of wirings, formed on or over the (n−1)-th wiring layer;  
 a low-dielectric-constant insulating film provided on the (n−1)-th insulating film formed as having a plane surface and the (n−1)-th wiring layer, and formed between adjacent wirings of the n-th wiring layer, located under the n-th wiring layer but on the (n−1)-th insulating film and the (n−1)-th wiring layer, at least a part of the low-dielectric-constant insulating film existing between the (n−1)-th and n-th wiring layers having a relative dielectric constant lower than a relative dielectric constant of the (n−1)-th insulating film.  
 
     
     
         13 . The semiconductor device according to  claim 12 , further comprising: 
 a third insulating film formed on the second wiring layer or the second insulating film;    a third wiring layer formed on the third insulating film; and    a second plug connecting several wirings of the second and third wiring layers, formed in the third insulating film.    
     
     
         14 . The semiconductor device according to  claim 12 , wherein the cap layer is buried in the second through n-th insulating layers together with the second through n-th wiring layers.  
     
     
         15 . The semiconductor device according to  claim 12 , further comprising: 
 a plug connecting several wirings of the (n−1)-th and n-th wiring layers, formed in the n-th insulating film; and    a low-dielectric-constant insulating film formed between the wirings of the n-th wiring layer and between the n-th wiring layer and the n-th insulating film or the plug, the low-dielectric-constant insulating film having a relative dielectric constant lower than a relative dielectric constant of the nth insulating film.    
     
     
         16 . A method of producing a semiconductor device having a plurality of wiring layers comprising: 
 forming a first interlayer-insulating film;    forming a plurality of grooves for wiring in the first interlayer-insulating film;    filling metallic films in the groves to form wirings;    etching the first interlayer-insulating film with the wirings as a mask and removing the interlayer-insulating film between the wirings to provide groves to be filled; and    filling a second interlayer-insulating film made of a material of low dielectric constant in the groves to be filled.    
     
     
         17 . A method of producing a semiconductor device having a plurality of wiring layers comprising: 
 forming a first interlayer-insulating film;    forming a plurality of grooves for wiring in the first interlayer-insulating film;    filling metallic films in the wiring groves to form wirings;    etching the first interlayer-insulating film with the wirings as a mask and removing the interlayer-insulating film between the wirings to provide groves to be filled;    filling a second interlayer-insulating film made of at least one insulating film in the groves to be filled, the insulating film being made of a material selected from the group consisting of resin having siloxane bonding as a major structure, resin having C—C bonding as a major structure and a resin having C═C bonding as a major structure; and    changing the second interlayer-insulating film into a porous insulating film.    
     
     
         18 . The method of producing a semiconductor device according to  claim 17 , wherein the second interlayer-insulating film is changed into the porous insulating film by annealing the second interlayer-insulating film in an NH 3 -gas ambient or with electron-beam irradiation.  
     
     
         19 . The method of producing a semiconductor device according to  claim 17 , wherein the second interlayer-insulating film is changed into the porous insulating film by dehydrating polymerization and solvent evaporation with annealing at a temperature in the range from 300 to 450° C.  
     
     
         20 . The method of producing a semiconductor device according to  claim 19 , wherein the second interlayer-insulating film is changed into the porous insulating film by annealing the second interlayer-insulating film in an NH 3 -gas ambient or with electron-beam irradiation.  
     
     
         21 . A method of producing a semiconductor device having a plurality of wiring layers comprising: 
 forming a first interlayer-insulating film;    performing dehydrating polymerization to the first interlayer-insulating film;    forming a plurality of grooves for wiring in the dehydrating-polymerized first interlayer-insulating film;    filling metallic films in the wiring groves to form wirings; and    applying a solvent to the dehydrating-polymerized first interlayer-insulating film after the wiring formation.    
     
     
         22 . The method of producing a semiconductor device according to  claim 21 , wherein the dehydrating polymerization is performed by annealing the first interlayer-insulating film in an NH 3 -gas ambient or with electron-beam irradiation.