Method of forming fine patterns of a semiconductor device
A method of forming fine patterns includes forming an upper mask layer on a substrate, forming preliminary mask patterns on the upper mask layer, and forming upper mask patterns by etching the upper mask layer using the preliminary mask patterns as etch masks. Forming the upper mask patterns includes etching the upper mask layer by performing an etching process using an ion beam. The upper mask patterns include a first upper mask pattern formed under each of the preliminary mask patterns, and a second upper mask pattern formed between the preliminary mask patterns in a plan view and spaced apart from the first upper mask pattern.
1. A method of forming fine patterns, the method comprising:
forming an upper mask layer on a substrate;
forming preliminary mask patterns on the upper mask layer; and
forming upper mask patterns by etching the upper mask layer using the preliminary mask patterns as etch masks,
wherein forming the upper mask patterns includes etching the upper mask layer by performing an etching process using an ion beam, and
wherein the upper mask patterns include a first upper mask pattern and a second mask pattern formed simultaneously by the etching process, the first upper mask pattern vertically overlaps each of the preliminary mask patterns; and the second upper mask pattern is laterally spaced apart from the first upper mask pattern.
2. The method as claimed in claim 1 , further comprising controlling an incident angle of the ion beam during the etching process to project a shaded area onto which the ion beam is not irradiated on the upper mask layer between the preliminary mask patterns.
3. The method as claimed in claim 2 , wherein at least a portion of the shaded area of the upper mask layer is not removed by the etching process to define the second upper mask pattern.
4. The method as claimed in claim 1 , wherein an incident angle of the ion beam is equal to or greater than a first angle and less than a second angle during the etching process, and
wherein the first angle and the second angle are defined by the following equation 1 and the following equation 2, respectively,
θ a =arctan( H/d 1) [Equation 1]
θ b =arctan((2× H )/ d 1) [Equation 2]
where “θa” and “θb” are the first angle and the second angle, respectively, “H” is a height of each of the preliminary mask patterns, and “d 1 ” is a distance between the preliminary mask patterns.
5. The method as claimed in claim 1 , wherein:
etching the upper mask layer includes forming a pair of openings penetrating the upper mask layer between a pair of the preliminary mask patterns adjacent to each other, and
the second upper mask pattern has sidewalls defined by the pair of openings.
6. The method as claimed in claim 5 , wherein the first upper mask pattern is spaced apart from the second upper mask pattern by a corresponding one of the pair of openings.
7. The method as claimed in claim 6 , wherein:
each of the pair of openings has a width in a direction parallel to a top surface of the substrate, and
etching the upper mask layer includes controlling at least one of an incident angle, an ion energy, an ion current, or an irradiation time of the ion beam to adjust the width of each of the pair of openings.
8. The method as claimed in claim 5 , wherein:
each of the preliminary mask patterns has a first sidewall and a second sidewall opposite to each other,
the first sidewall of each of the preliminary mask patterns faces the second sidewall of the preliminary mask pattern adjacent directly to each of the preliminary mask patterns,
the ion beam includes
a first ion beam irradiated toward the first sidewall of each of the preliminary mask patterns, and
a second ion beam irradiated toward the second sidewall of each of the preliminary mask patterns,
each of the pair of openings has a width in a direction parallel to a top surface of the substrate,
etching the upper mask layer includes controlling the first and second ion beams to have at least one of an incident angle, an ion energy, an ion current, or an irradiation time different from one another to adjust widths of the pair of openings to be different from one another.
9. The method as claimed in claim 1 , wherein etching the upper mask layer includes using an inert gas as an ion source.
10. The method as claimed in claim 9 , wherein the preliminary mask patterns include a material having an interatomic bonding strength stronger than that of the upper mask layer.
11. The method as claimed in claim 1 , wherein:
etching the upper mask layer includes using a reactive gas as an ion source, and
the preliminary mask patterns include a material having an etch selectivity with respect to the upper mask layer.
12. The method as claimed in claim 1 , further comprising:
forming an etch target layer between the substrate and the upper mask layer;
forming a lower mask layer between the etch target layer and the upper mask layer;
etching the lower mask layer using the upper mask patterns as etch masks to form lower mask patterns; and
etching the etch target layer using the lower mask patterns as etch masks to form patterns.
13. The method as claimed in claim 1 , wherein a pitch of the upper mask patterns is smaller than a pitch of the preliminary mask patterns.
14. A method of forming fine patterns, the method comprising:
forming an upper mask layer on a substrate;
forming preliminary mask patterns on the upper mask layer; and
forming upper mask patterns by etching the upper mask layer using the preliminary mask patterns as etch masks,
wherein forming the upper mask patterns includes etching the upper mask layer using an ion beam and controlling an incident angle of the ion beam during etching to project a shaded area onto which the ion beam is not irradiated on the upper mask layer between the preliminary mask patterns.
15. The method as claimed in claim 14 , wherein the incident angle of the ion beam is equal to or greater than a first angle and less than a second angle, and
wherein the first angle and the second angle are defined by the following equation 1 and the following equation 2, respectively,
θ a =arctan( H/d 1) [Equation 1]
θ b =arctan((2× H )/ d 1) [Equation 2]
where “θa” and “θb” are the first angle and the second angle, respectively, “H” is a height of each of the preliminary mask patterns, and “d 1 ” is a distance between the preliminary mask patterns.
16. The method as claimed in claim 15 , wherein each of the preliminary mask patterns has a first sidewall and a second sidewall opposite to each other,
wherein the first sidewall of each of the preliminary mask patterns faces the second sidewall of the preliminary mask pattern adjacent directly to each of the preliminary mask patterns,
wherein the ion beam includes a first ion beam irradiated toward the first sidewall of each of the preliminary mask patterns; and a second ion beam irradiated toward the second sidewall of each of the preliminary mask patterns,
wherein an incident angle of each of the first and second ion beams is equal to or greater than the first angle and less than the second angle.
17. The method as claimed in claim 14 , wherein:
the upper mask patterns includes a first upper mask pattern formed under each of the preliminary mask patterns and a second upper mask pattern formed between the preliminary mask patterns in a plan view, and
at least a portion of the shaded area of the upper mask layer is not removed by etching but remains between the preliminary mask patterns in a plan view to define the second upper mask pattern.
18. The method as claimed in claim 17 , wherein the first upper mask pattern and the second upper mask pattern are spaced apart from each other in a direction parallel to a top surface of the substrate.
19. The method as claimed in claim 18 , wherein the first upper mask pattern and the second upper mask pattern are alternately and repeatedly arranged in the direction parallel to the top surface of the substrate.
20. A method of forming fine patterns, the method comprising:
forming an upper mask layer on a substrate;
forming preliminary mask patterns on the upper mask layer, each preliminary mask pattern having a first sidewall and a second sidewall, opposite the first sidewall; and
forming upper mask patterns by etching the upper mask layer using the preliminary mask patterns as etch masks by controlling a first incident angle of a first ion beam incident on the first sidewall of each of the preliminary mask patterns and a second incident angle of a second ion beam incident on the second sidewalls of each of the preliminary mask patterns to project a shaded area onto which neither of the first and second ion beam are irradiated on the upper mask layer between the preliminary mask patterns.