Three dimensional semiconductor memory device and method of fabricating the same
Provided are a three dimensional semiconductor memory device and a method of fabricating the same. The method includes forming a stepwise structure by using mask patterns and a sacrificial mask pattern formed on the mask patterns as a consumable etch mask.
1. A method of fabricating a three dimensional semiconductor device, the method comprising;
forming a layer structure comprising a plurality of sequentially stacked layers on a substrate;
forming a mask structure comprising a plurality of horizontally arranged mask patterns on the layer structure;
forming a sacrificial mask pattern on the mask structure; and
forming a stepwise contact structure by patterning the layer structure using the mask structure and the sacrificial mask pattern as a consumable etch mask.
2. The method of claim 1 , wherein patterning the layer structure comprises a plurality of sub-patterning processes, each of the plurality of sub-patterning processes comprising:
exposing one of the mask patterns covered by the sacrificial mask pattern used in a sub-patterning process performed before the exposing;
removing the exposed mask pattern; and
etching a portion of the layer structure below the removed mask pattern.
3. The method of claim 2 , wherein etching the layer structure comprises etching the layer structure etched in the previous sub-patterning process.
4. The method of claim 2 , wherein exposing one of the mask patterns comprises horizontally etching a sidewall of the sacrificial mask pattern.
5. The method of claim 2 , wherein forming the mask structure comprises alternately forming first mask patterns and second mask patterns arranged horizontally, and wherein the first mask patterns are formed of a material different from that of the second mask patterns.
6. The method of claim 5 , wherein the first mask patterns and the second mask patterns are located at different heights.
7. The method of claim 5 , wherein prior to forming the sacrificial mask pattern, the method further comprising:
forming active semiconductor patterns penetrating the plurality of sequentially stacked layers; and
forming doped semiconductor patterns contacting an upper region of each of the active semiconductor patterns,
wherein the first mask patterns are formed using the doped semiconductor patterns.
8. The method of claim 7 , wherein the first mask patterns and the doped semiconductor patterns are doped with an impurity comprising a conductive type which is different from that of the active semiconductor patterns.
9. The method of claim 1 , wherein each of the mask patterns is formed thicker than a maximum thickness of each of the layers.
10. The method of claim 1 , wherein the substrate comprises a cell array region in which memory cells are disposed, and a contact region disposed on at least one side of the cell array region,
the three dimensional semiconductor device further comprises active semiconductor patterns penetrating the layer structure in the cell array region,
wherein a deviation in distance between the mask patterns and the active semiconductor patterns adjacent to the mask patterns is smaller than half of a distance between the sidewalls of the mask patterns.
11. The method of claim 10 , wherein the sidewall of one of the mask patterns meets the below equation
L
(
y
m
)
-
L
(
y
0
)
<
W
(
y
0
)
s
,
within a range of y m meeting the condition of |y m −y 0 |<y 1 ,
where y 0 is a y coordinate of a reference point, y n , is a y coordinate of a measured point, L n (y m ) is a distance between one point on one sidewall of the mask pattern in which the y coordinate is y m , and an edge of the cell array region, W(y 0 ) is a width of a corresponding mask pattern, s is a value between about 2 to 20, and y 1 is a length shorter than a length of the mask pattern.
12. The method of claim 11 , wherein the parameter y 1 is about 80% to about 100% of the length of the bit line.
13. The method of claim 11 , wherein the parameter y1 is about 80% to about 120% of the width of the mask pattern.
14. A method of fabricating a three dimensional semiconductor device, the method comprising:
forming a layer structure comprising a plurality of sequentially stacked layers on a substrate;
forming a mask structure comprising a plurality of horizontally arranged mask patterns on the layer structure; and
forming a pattern structure comprising a stepwise contact structure by patterning the layer structure,
wherein forming the pattern structure comprises a plurality of sub-patterning processes, each of the plurality of sub-patterning processes comprising a horizontal etch process selectively removing at least one of the mask patterns, and a vertical etch process etching the layer structure disposed below the mask pattern removed in the horizontal etch process.
15. The method of claim 14 , wherein each of the sub-patterning processes comprises etching the layer structure etched in a previous sub-patterning process.