Methods of cutting a fine pattern, methods of forming active patterns using the same, and methods of manufacturing a semiconductor device using the same
In a method of cutting a fine pattern, a line structure is formed on a substrate. The line structure extends in a first direction, and includes a pattern and a first mask. The pattern and the first mask include different materials. A sacrificial layer is formed on the substrate to cover the line structure. The sacrificial layer is partially etched to form a first opening partially overlapping the line structure in a vertical direction. A portion of the first mask, an upper portion of the pattern and/or a portion of the sacrificial layer under the first opening are partially etched using an etching gas having no etching selectivity among the pattern, the first mask and the sacrificial layer. A lower portion of the pattern under the upper portion thereof is removed to divide the pattern into a plurality of pieces spaced apart from each other in the first direction.
1. A method of forming active patterns, the method comprising:
forming a line structure on a substrate, the line structure extending in a first direction parallel to an upper surface of the substrate;
forming a sacrificial layer on the substrate to cover the line structure;
sequentially forming a first mask layer and a photoresist pattern on the sacrificial layer, the first mask layer including silicon oxynitride and the photoresist pattern including a first opening exposing an upper surface of the first mask layer;
etching the first mask layer by an etching process using the photoresist pattern as an etching mask to form a first mask having a second opening exposing an upper surface of the sacrificial layer, the etching process using a first etching gas including SF 6 gas and CHF 3 gas so that carbon-sulfur (C—S) bonds are formed on a surface of the photoresist pattern to restrain etching of the photoresist pattern, and a slope of the second opening having an angle equal to or greater than 80 degrees with respect to the upper surface of the substrate;
partially etching the sacrificial layer using the first mask as an etching mask to form a third opening exposing a portion of the line structure;
removing the portion of the line structure exposed by the third opening to divide the line structure into a plurality of pieces spaced apart from each other in the first direction; and
etching an upper portion of the substrate using the plurality of line structures as an etching mask to form a plurality of active patterns spaced apart from each other in the first direction.
2. The method according to claim 1 , further comprising:
prior to forming the line structure on the substrate, forming a first layer on the substrate,
wherein etching the upper portion of the substrate using the plurality of line structures as the etching mask includes:
etching the first layer using the plurality of line structures as an etching mask to form a plurality of first patterns spaced apart from each other in the first direction; and
etching the upper portion of the substrate using the plurality of line structures and the plurality of first patterns as an etching mask.
3. The method according to claim 1 , further comprising, prior to etching the first mask layer to form the first mask:
forming a spacer layer on the upper surface of the first mask layer exposed by the first opening, a sidewall of the first opening and an upper surface of the photoresist pattern through an ALD process; and
anisotropically etching the spacer layer to form a spacer on the sidewall of the first opening,
wherein etching the first mask layer is performed using the photoresist pattern and the spacer as an etching mask.
4. The method according to claim 1 , wherein the line structure includes a second pattern and a second mask sequentially stacked on the substrate, the second pattern and the second mask including polysilicon and an oxide, respectively.
5. The method according to claim 4 , wherein dividing the line structure into the plurality of pieces spaced apart from each other includes:
etching a portion of the second mask exposed by the third opening and an upper portion of the pattern thereunder using a second etching gas having no etching selectivity among the second pattern, the second mask, and the sacrificial layer to form a fourth opening; and
removing a portion of the second pattern exposed by the fourth opening.
6. The method according to claim 5 , wherein the second etching gas includes CF 4 gas and CHF 3 gas.
7. The method according to claim 1 , wherein:
the line structure is one of a plurality of line structures spaced apart from each other in a second direction parallel to the upper surface of the substrate and perpendicular to the first direction,
the third opening is one of a plurality of third openings spaced apart from each other in the second direction, and each of the plurality of third openings partially exposes a corresponding one of the plurality of line structures, and
the plurality of active patterns are spaced apart from each other in each of the first and second directions.
8. A method of manufacturing a semiconductor device, the method comprising:
forming a line structure on a substrate, the line structure extending in a first direction parallel to an upper surface of the substrate and including a pattern and a mask sequentially stacked, the pattern and the mask including different materials from each other;
forming a sacrificial layer on the substrate to cover the line structure;
partially etching the sacrificial layer to form a first opening partially overlapping the line structure in a vertical direction perpendicular to the upper surface of the substrate;
etching at least one of a portion of the mask, an upper portion of the pattern, and a portion of the sacrificial layer that are under the first opening using an etching gas to form a second opening, the etching gas having no etching selectivity among the pattern, the mask, and the sacrificial layer;
removing a lower portion of the pattern under the upper portion thereof to divide the pattern into a plurality of pieces spaced apart from each other in the first direction;
etching an upper portion of the substrate using the plurality of patterns as an etching mask to form a plurality of active patterns spaced apart from each other in the first direction;
forming a gate structure to be buried at upper portions of the plurality of active patterns;
forming a bit line structure on the plurality of active patterns to be electrically connected thereto; and
forming a capacitor on the plurality of active patterns to be electrically connected thereto.
9. The method according to claim 8 , wherein:
the line structure is one of a plurality of line structures spaced apart from each other in a second direction parallel to the upper surface of the substrate and perpendicular to the first direction,
the first opening is one of a plurality of first openings spaced apart from each other in the second direction, and each of the plurality of first openings partially overlaps a corresponding one of the plurality of line structures, and
the plurality of active patterns are spaced apart from each other in each of the first and second directions.
10. The method according to claim 9 ,
wherein the gate structure extends in a third direction parallel to the upper surface of the substrate and has an acute angle with respect to the first and second directions, and the gate structure is one of a plurality of gate structures spaced apart from each other in a fourth direction parallel to the upper surface of the substrate and perpendicular to the third direction, and
wherein the bit line structure extends in the fourth direction, and the bit line structure is one of a plurality of bit line structures spaced apart from each other in the third direction.
11. The method according to claim 10 ,
wherein each of the plurality of bit line structures contacts an upper surface of a central portion in the first direction of a corresponding one of the plurality of active patterns, and
wherein the capacitor is electrically connected to one of opposite ends in the first direction of a corresponding one of the plurality of active patterns.
12. The method according to claim 11 , further comprising a contact plug structure electrically connecting the capacitor to the one of opposite ends in the first direction of the corresponding one of the plurality of active patterns.
13. A method of manufacturing a semiconductor device, the method comprising:
forming a line structure on a substrate, the line structure extending in a first direction parallel to an upper surface of the substrate;
forming a sacrificial layer on the substrate to cover the line structure;
sequentially forming a mask layer and a photoresist pattern on the sacrificial layer, the mask layer including silicon oxynitride and the photoresist pattern including a first opening exposing an upper surface of the mask layer;
etching the mask layer by an etching process using the photoresist pattern as an etching mask to form a mask having a second opening exposing an upper surface of the sacrificial layer, the etching process using an etching gas including SF 6 gas and CHF 3 gas so that carbon-sulfur (C—S) bonds are formed on a surface of the photoresist pattern to restrain etching of the photoresist pattern, and a slope of the second opening having an angle equal to or greater than 80 degrees with respect to the upper surface of the substrate;
partially etching the sacrificial layer using the mask as an etching mask to form a third opening exposing a portion of the line structure;
removing the portion of the line structure exposed by the third opening to divide the line structure into a plurality of pieces spaced apart from each other in the first direction;
etching an upper portion of the substrate using the plurality of line structures as an etching mask to form a plurality of active patterns spaced apart from each other in the first direction;
forming a gate structure to be buried at upper portions of the plurality of active patterns;
forming a bit line structure on the plurality of active patterns to be electrically connected thereto; and
forming a capacitor on the plurality of active patterns to be electrically connected thereto.
14. The method according to claim 13 , wherein:
the line structure is one of a plurality of line structures spaced apart from each other in a second direction parallel to the upper surface of the substrate and perpendicular to the first direction,
the third opening is one of a plurality of third openings spaced apart from each other in the second direction, and each of the plurality of third openings partially exposes a corresponding one of the plurality of line structures, and
the plurality of active patterns are spaced apart from each other in each of the first and second directions.
15. The method according to claim 14 , wherein:
the gate structure extends in a third direction parallel to the upper surface of the substrate and having an acute angle with respect to the first and second directions, and the gate structure is one of a plurality of gate structures spaced apart from each other in a fourth direction parallel to the upper surface of the substrate and perpendicular to the third direction,
the bit line structure extends in the fourth direction, the bit line structure is one of a plurality of bit line structures spaced apart from each other in the third direction, and each of the plurality of bit line structures contacts an upper surface of a central portion in the first direction of a corresponding one of the plurality of active patterns, and
the capacitor is electrically connected to one of opposite ends in the first direction of a corresponding one of the plurality of active patterns.