Semiconductor device manufacturing method
A method of manufacturing a semiconductor device having a first memory cell array region and a second memory cell array region, the method includes forming an active region on a surface layer of a semiconductor substrate, forming a first word line extending in a first direction on the gate insulating film in the first memory cell array region, and forming a second word line extending in a second direction crossing the first direction on the gate insulating film in the second memory cell array region, wherein the ion implantation into the active region is performed from a direction that is inclined from a direction vertical to the surface of the semiconductor substrate and is oblique with respect to both the first direction and the second direction.
1. A method of manufacturing a semiconductor device having a first memory cell array region and a second memory cell array region, the method comprising:
forming an active region on a surface layer of a semiconductor substrate;
forming a first conductive type channel region in the active region;
forming a gate insulating film on the semiconductor substrate in the channel region;
forming a first word line extending in a first direction on the gate insulating film in the first memory cell array region, and forming a second word line extending in a second direction crossing the first direction on the gate insulating film in the second memory cell array region;
forming a resist pattern covering part of an upper surface of the first word line so as to put, in an exposed state, one side surface of the first word line and a bit contact region of the semiconductor substrate; and
ion-implanting an impurity having the same conductive type as the first conductive type into the active region of the bit contact region side using the resist pattern as a mask,
wherein the ion implantation into the active region is performed from a direction that is inclined from a direction vertical to the surface of the semiconductor substrate and is oblique with respect to both the first direction and the second direction.
2. The method of manufacturing the semiconductor device according to claim 1 , wherein
in the forming the resist pattern, in a state where one side surface of the second word line and the bit contact region of the semiconductor substrate are exposed, the resist pattern is formed so as to cover part of an upper surface of the second word line, and
in the ion-implanting the impurity into the active region, the ion implantation is performed a plurality of times each by changing a twist angle.
3. The method of manufacturing the semiconductor device according to claim 2 , wherein
in the forming the first word line and the second word line, the first word line and the second word line are formed so that the first direction is orthogonal to the second direction, and
in the ion-implanting the impurity in the active region, the ion implantation is performed four times each by changing the twist angle by 90°.
4. The method of manufacturing the semiconductor device according to claim 1 , wherein
in the ion-implanting the impurity in the active region, the angle of implanting the impurity with respect to the direction vertical to the surface of the semiconductor substrate, the angle is selected so that an area that implanting is blocked out by the resist pattern does not reach the first word line.
5. The method of manufacturing the semiconductor device according to claim 1 , wherein
in the ion-implanting the impurity in the active region, when there is a space between surface in the first word line and the resist pattern in the first word line due to a manufacturing error, the direction of implanting the impurity with respect to the direction vertical to the surface of the semiconductor substrate is selected within a range so that the first word line shields the space from the ion-implanting.
6. The method of manufacturing the semiconductor device according to claim 1 , wherein
an end side surface of the resist pattern is positioned over the center of the upper surface of the first word line.
7. The method of manufacturing the semiconductor device according to claim 1 , wherein
the first memory cell array region and the second memory cell array region are included in a first memory macro and a second memory macro each having the same planar shape respectively, and the second memory macro is positioned at a rotation 90° different from the first memory macro within a substrate surface of the semiconductor substrate.
8. The method of manufacturing the semiconductor device according to claim 7 , wherein
the planar shape of the first memory macro and the second memory macro is a rectangular shape.
9. The method of manufacturing the semiconductor device according to claim 1 , further comprising:
forming an impurity diffused region having another conductive type opposite to the first conductive type in the semiconductor substrate adjacent to a side of the first word line; and
forming a cell capacitor electrically connected to the impurity diffused region.
10. The method of manufacturing the semiconductor device according to claim 9 , wherein
the cell capacitor has a capacitor upper electrode formed over the gate insulating film on the semiconductor substrate in the active region, and
the gate insulating film below the capacitor upper electrode serves as a capacitor dielectric film, and the active region below the capacitor upper electrode serves as a capacitor lower electrode.
11. The method of manufacturing the semiconductor device according to claim 10 , wherein
the capacitor upper electrode is formed concurrently with the forming the first word line and the second word line.
12. The method of manufacturing the semiconductor device according to claim 9 , wherein
the first word line also serves as a gate electrode of a transfer transistor connected to the cell capacitor, and the impurity diffused region is a source/drain extension of the transfer transistor.