Semiconductor memory device and manufacturing method thereof

Abstract

After an ONO film in which a silicon nitride film ( 22 ) formed by a plasma nitriding method using a plasma processor having a radial line slot antenna is sandwiched by silicon oxide films ( 21 ), ( 23 ), a bit line diffusion layer ( 17 ) is formed in a memory cell array region ( 11 ) by an ion implantation as a resist pattern ( 16 ) taken as a mask, then lattice defects are given to the silicon nitride film ( 22 ) by a further ion implantation. Accordingly, a highly reliable semiconductor memory device can be realized, in which a high quality nitride film is formed in a low temperature condition, in addition, the nitride film can be used as a charge trap film having a charge capture function sufficiently adaptable for a miniaturization and a high integration which are recent demands.

1 . A semiconductor memory device, comprising:
 a semiconductor substrate;   an insulating film formed on said semiconductor substrate and including a nitride film having a charge capture function;   a gate electrode formed on said semiconductor substrate through said insulating film;   a pair of impurity diffusion layers formed on said semiconductor substrate, and wherein said nitride film includes charge trap centers with lattice defects formed at a specified portion of the nitride film.   
     
     
         2 . The semiconductor memory device according to  claim 1 ,
 wherein said nitride film is a plasma nitride film of a densified structure formed by nothing but a plasma nitriding by exiting a microwave or by a series of processes including the plasma nitriding.   
     
     
         3 . The semiconductor memory device according to  claim 1 ,
 wherein said insulating film is a stacked film in which said nitride film is formed on an oxide film.   
     
     
         4 . The semiconductor memory device according to  claim 1 ,
 wherein said insulating film is a stacked film in which said nitride film is sandwiched between respective upper and lower oxide films.   
     
     
         5 . The semiconductor memory device according to  claim 1 ,
 wherein said insulating film is constituted by nothing but said nitride film.   
     
     
         6 . The semiconductor memory device according to  claim 3 ,
 wherein said impurity diffusion layer doubles as a bit line.   
     
     
         7 . The semiconductor memory device according to  claim 4 ,
 wherein said impurity diffusion layer doubles as a bit line.   
     
     
         8 . The semiconductor memory device according to  claim 5 ,
 wherein said impurity diffusion layer doubles as a bit line.   
     
     
         9 . The semiconductor memory device according to  claim 3 ,
 wherein a bit line electrically connected to said impurity diffusion layer is provided in an upper portion of said impurity diffusion layer.   
     
     
         10 . The semiconductor memory device according to  claim 4 ,
 wherein a bit line electrically connected to said impurity diffusion layer is provided in an upper portion of said impurity diffusion layer.   
     
     
         11 . The semiconductor memory device according to  claim 5 ,
 wherein a bit line electrically connected to said impurity diffusion layer is provided in an upper portion of said impurity diffusion layer.   
     
     
         12 . A manufacturing method of a semiconductor memory device including:
 a semiconductor substrate;   an insulating film formed on said semiconductor substrate and including a nitride film having a charge capture function;   a gate electrode formed on said semiconductor substrate through said insulating film; and   a pair of impurity diffusion layers formed on said semiconductor substrate, comprising a step of:   forming charge trap centers by giving lattice defects to a part or the whole of the nitride film after the nitride film is formed by a plasma nitriding method.   
     
     
         13 . The manufacturing method of the semiconductor memory device according to  claim 12 ,
 wherein the charge trap centers are formed by introducing an impurity into the nitride film before or after the impurity diffusion layers are formed.   
     
     
         14 . The manufacturing method of the semiconductor memory device according to  claim 12 ,
 wherein the lattice defects are given by performing a radio frequency processing using an inert gas to the nitride film before or after the impurity diffusion layers are formed.   
     
     
         15 . The manufacturing method of the semiconductor memory device according to  claim 12 ,
 wherein the nitride film is formed by performing a nitriding processing with the plasma excited by a microwave in an atmosphere of a source gas including nitrogen atoms for generating a nitride radical.