Method of manufacturing a semiconductor integrated circuit device

Abstract

In forming five trenches buried with an intermediate conductive layer for connecting transfer MISFETs and driving MISFETs with vertical MISFETs formed thereover, in which the second and third trenches, and the first, fourth, and fifth trenches are formed separately by twice etching using first and second photoresist films as a mask. Since all the trenches can be formed at a good accuracy even in a case where the shortest distance between the first trench and the second or third trench, and the shortest distance between the second or third trench and the fourth trench is smaller than the resolution limit for the exposure light, the distance between each of the five trenches arranged in one identical memory cell can be reduced to be smaller than resolution limit for the exposure light.

1 . A method of manufacturing a semiconductor integrated circuit device, comprising steps of:
 (a) forming a first insulating film over a semiconductor substrate;   (b) forming a mask material over the first insulating film;   (c) forming a first opening in the first mask material;   (d) after the step (c), forming a second opening in the first mask material;   (e) after the step (d), removing the first insulating film by using the mask material as a mask,   wherein, in the step (e), a first trench is formed in the first insulating film and is positioned at the area of the first insulating film exposed by the first opening,   wherein, in the step (e), a second trench is formed in the first insulating film and is positioned at the area of the first insulating film exposed by the second opening;   (f) forming a first and second conductive film with the first and the second trench, respectively;   (g) forming a second insulating film over the first insulating film;   (h) forming a second mask material over the second insulating film;   (i) forming a third opening in the second mask material;   (j) after the step (i), forming a fourth opening in the second mask material;   (k) after the step (j), removing the second insulating film by using the second mask material as a mask,   wherein, the step (k), a third trench is formed in the second insulating film and is positioned at the area of the second insulating film exposed by the third opening,   wherein, in step (k), a fourth trench is formed in the second insulating film and is positioned at the area of the second insulating film exposed by the fourth opening; and   (i) forming a third and fourth conductive film within the third and the fourth trench, respectively.   
     
     
         2 . A method according to  claim 1 , wherein the first mask material serves as a hard mask in the step (e). 
     
     
         3 . A method according to  claim 1 , wherein the second mask material serves as a hard mask in the step (h). 
     
     
         4 . A method according to  claim 1 , wherein the first opening is formed by using a first resist film,
 wherein the second opening is formed by using a second resist film.