Semiconductor memory devices

1. A semiconductor device comprising:

a plurality of cell gate electrodes extending in a first direction, each of the cell gate electrodes disposed in a cell region of a semiconductor substrate with a cell gate dielectric layer disposed between the cell gate electrode and the semiconductor substrate;

a plurality of bit lines extending in a second direction perpendicular to the first direction; and

a plurality of data storage elements arranged along the first and second directions, the data storage elements electrically connected between the bit lines and a doped region formed adjacent to the cell gate electrode;

wherein each of the bit lines is in direct contact with the data storage elements arranged along the second direction, and

wherein each of the bit lines includes first portions contacting with the data storage elements and a second portion between the data storage elements, and

wherein the first portions have a first thickness and the second portion has a second thickness greater than the first thickness.

2. The semiconductor device of claim 1 , wherein widths of bottom surfaces of the bit lines are smaller than corresponding widths of top surfaces of the data storage elements.

3. The semiconductor device of claim 1 , further comprising a peripheral gate electrode formed over a flat surface of the semiconductor substrate in a peripheral circuit region.

4. The semiconductor device of claim 1 , wherein each of the bit lines has a non-planar bottom surface and a substantially planar top surface.

5. A semiconductor device comprising:

a semiconductor substrate including a cell region and a peripheral region;

a cell active portion defined in a semiconductor substrate of the cell region;

a cell gate dielectric layer and a cell gate electrode crossing the cell active portion;

a first doped region and a second doped region within the cell active portion at both sides of the cell gate electrode, respectively;

first and second interlayer insulating layers sequentially stacked on the semiconductor substrate;

a source line disposed in the first interlayer insulating layer and connected to the first doped region, wherein the second interlayer insulating layer covers a top surface of the source line;

a contact plug penetrating the first and second interlayer insulating layers and connected to the second doped region;

a data storage element disposed on the first and second insulating layers and electrically connected to the second doped region through the contact plug;

a mold layer covering the data storage element;

a bit line disposed in a cell groove penetrating the mold layer, the bit line directly contacting a top surface of the data storage element;

a peripheral transistor formed at a peripheral active portion defined at the semiconductor substrate of the peripheral region, the peripheral transistor including a peripheral source/drain region;

a peripheral plug penetrating the first interlayer insulating layer and connected to the peripheral source/drain region; and

a peripheral wire connected to the peripheral plug,

wherein top surfaces of the bit line and the peripheral wire are substantially coplanar with the top surface of the mold layer, and

wherein a bottom surface of the peripheral wire is lower than a bottom surface of the data storage element and is substantially coplanar with the top surface of the source line, and

wherein the bit line extends along one direction to be contact with a portion of the mold layer, and

wherein the bit line has a first thickness on the top surface of the data storage element and a second thickness greater than the first thickness on the portion of the mold layer.

6. The semiconductor device of claim 5 , wherein the peripheral wire is formed of the same conductive material as the bit line.

7. The semiconductor device of claim 5 , wherein a width of the bottom surface of the peripheral wire is smaller than a width of a top surface of the peripheral plug, and a width of a top surface of the peripheral wire is greater than the width of the bottom surface of the peripheral wire.