Method for forming fine pattern of semiconductor device
A method for forming a fine pattern of a semiconductor device comprises forming a deposition pattern including first, second, and third mask patterns over a semiconductor substrate having an underlying layer, side-etching the second mask pattern with the third mask pattern as an etching barrier mask, removing the third mask pattern, forming a spin-on-carbon layer that exposes the upper portion of the second mask pattern, performing an etching process to expose the underlying layer with the spin-on-carbon layer as an etching barrier mask, and removing the spin-on-carbon layer.
1. A method for forming a fine pattern of a semiconductor device, the method comprising:
forming a stack film including a first mask film, a second mask film, and a third mask film over a semiconductor substrate having an underlying layer;
forming a photoresist pattern over the third mask film;
patterning the third mask film using the photoresist pattern as an etching barrier mask to form a third mask pattern;
patterning the first and second mask films using the third mask pattern as an etching barrier mask to form a first and second mask patterns;
side-etching the second mask pattern using the third mask pattern as an etching barrier mask;
removing the third mask pattern;
forming a spin-on-carbon layer over the second mask pattern so that an upper portion of the second mask pattern is exposed;
performing an etching process to expose the underlying layer using the spin-on-carbon layer as an etching barrier mask so that the first mask pattern including an open part is formed; and
removing the spin-on-carbon layer.
2. The method according to claim 1 , wherein the underlying layer comprises a conductive layer with a stack pattern of an insulating film and a polymer layer as a top layer.
3. The method according to claim 1 , wherein the first mask film has a different etching selectivity ratio from that of the second mask film, and the third mask film has a different etching selectivity ratio from that of the second mask film.
4. The method according to claim 1 , wherein the first mask film is a tungsten layer.
5. The method according to claim 1 , wherein the second mask film is selected from the group consisting of a silicon nitride film, a silicon oxide film, a silicon oxy-nitride film, and combinations thereof.
6. The method according to claim 1 , wherein the third mask film is an amorphous carbon layer, a stack layer including an amorphous carbon layer and a silicon oxide nitride film, or a multi mask film.
7. The method according to claim 6 , wherein the multi mask film is formed by a spin-on-carbon material where a carbon element is present in an amount in a range of 85 wt % to 90 wt % based on the total compound molecular weight, or a mask composition comprising a Si compound where a Si element is present in an amount in a range of 30 wt % to 80 wt % by weight based on the total compound molecular weight.
8. The method according to claim 7 , wherein the multi mask film is formed by a mask composition comprising a Si compound selected from the group consisting of a Si-containing polymer, an oligomer of the Si-containing polymer and a spin-on glass material.
9. The method according to claim 8 , wherein the spin-on glass material is Hydrogen Silses-Quioxane (HSQ) or Methyl Silses-Quioxane (MSQ).
10. The method according to claim 1 , comprising side-etching the second mask pattern by a trimming etching process.
11. The method according to claim 10 , wherein the trimming etching process has a higher polishing speed in the second mask film than that of either the first or the third mask film.
12. The method according to claim 10 , further comprising performing the trimming etching process with an etching gas having a flow ratio of a fluorohydrocarbon gas to SF 6 of 2-10:1.
13. The method according to claim 12 , wherein the fluorohydrocarbon gas is a CHF 3 gas.
14. The method according to claim 1 , further comprising performing a side-etching process to reduce the line-width of the second mask pattern by 20-50% in comparison with that of the second mask pattern before reduction.
15. The method according to claim 14 , further comprising performing a side-etching process to reduce the line-width of the second mask pattern by 30-40% in comparison with that of the second mask pattern before reduction.
16. The method according to claim 1 , further comprising performing a step of removing the third mask pattern and the spin-on-carbon layer by an oxygen ashing process.
17. The method according to claim 1 , further comprising performing the etching process using the spin-on-carbon layer as an etching barrier mask on the first and second mask patterns.
18. The method according to claim 1 , wherein after removing the spin-on-carbon layer, a ratio of line-width of the first mask pattern to interval between the patterns is 1:1.
19. The method according to claim 1 , wherein said patterning the first mask film comprises performing a partial etching onto the first mask film using the second and third mask patterns as an etching barrier mask; and performing an etching process to remove the spin-on-carbon layer and a portion of the first mask film until the underlying layer is exposed.
20. The method according to claim 19 , wherein the partial etching onto the first mask film is performed so as not to expose the underlying layer, whereby forming first mask patterns whose lower portions are interconnected.