Nanoimprinting method, and method for producing a droplet arrangement pattern
The disclosed nanoimprinting method suppresses fluctuations in thickness of residual film and defects due to residual gas in a resist film, onto which a pattern of protrusions and recesses is transferred, in a nanoimprinting method that employs the ink jet method to coat a substrate with droplets of resist material. Droplets are coated onto a substrate such that the spaces between the droplets along an A direction which is substantially parallel to the direction of the lines of a linear pattern of protrusions and recesses are longer than the spaces between the droplets in a B direction which is substantially perpendicular to the A direction, in a nanoimprinting method that coats a substrate with the droplets of a resist material using the ink jet method.
1. A nanoimprinting method, comprising:
coating a plurality of standard droplets of resist material at a standard amount onto a test substrate by an ink jet method;
pressing a test mold having a linear pattern of protrusions and recesses arranged in lines extending along a first direction against a surface of the test substrate which has been coated with the standard droplets, the pressing of the test mold onto the test substrate causing the standard droplets to spread to a degree that the standard droplets contact each other and causing shapes of the thus-spread standard droplets to be ellipses;
measuring two dimensional shapes of the ellipses by one of an optical method and a stylus method;
obtaining a two dimensional arrangement with the two dimensionally shaped ellipses being closely packed with the ellipses covering at least 70% of a two-dimensional image area;
extracting center coordinates of the ellipses which are arranged in the closely-packed two dimensional arrangement;
from the extracted center coordinates of the ellipses, obtaining a droplet arrangement pattern having the extracted center coordinates as lattice points that correspond to positions at which the plurality of droplets are to be arranged where the centers of each of the ellipses are lattice points in the obtained droplet arrangement pattern,
wherein, in the obtained droplet arrangement pattern, the lattice points define lines that extend in said first direction of the lines of the linear pattern of protrusions and recesses, and an average space (Wa) between centers of the droplets in an A direction substantially parallel to the first direction of the lines of the linear pattern of protrusions and recesses are longer than an average space (Wb) among droplets in a B direction substantially perpendicular to the A direction (Wa>Wb);
using the obtained droplet arrangement pattern, coating a surface of a further substrate with further droplets of resist material by the ink jet method; and
pressing a linear pattern of protrusions and recesses of a further mold onto the surface of the further substrate which has been coated with the further droplets according to the obtained droplet arrangement pattern to spread the further droplets on the further substrate to form a further resist film constituted by bonds among the spread further droplets and to transfer the linear pattern of protrusions and recesses of the further mold onto the resist film,
wherein when coating the further droplets on the further substrate, the further droplets are coated within a first line transfer region of the further substrate that faces the linear pattern of protrusions and recesses of the further mold when the linear pattern of protrusions is pressed against the further substrate.
2. The nanoimprinting method as defined in claim 1 , wherein:
a ratio Wa/Wb between the average space Wa between droplets in the A direction and the average space Wb between droplets in the B direction satisfies the following formula (1)
1.8 ≤Wa/Wb ≤0.52 V 1/3 /d (1)
wherein V represents the average volume of each coated droplet, and d represents the average thickness of the resist film.
3. The nanoimprinting method as defined in claim 1 , wherein:
the resolution in the A direction which is defined by an ink jet head that performs the coating with the droplets is set to be lower than the resolution in the B direction which is defined by the ink jet head.
4. The nanoimprinting method as defined in claim 2 , wherein:
the resolution in the A direction which is defined by an ink jet head that performs the coating with the droplets is set to be lower than the resolution in the B direction which is defined by the ink jet head.
5. The nanoimprinting method as defined in claim 3 , wherein:
one of the A direction and the B direction is set as a main scanning direction in the ink jet method, and the other is set as a sub scanning direction in the ink jet method; and
the ink jet head is set such that the intervals among lattice points along the sub scanning direction is an integer multiple of effective intervals among ink expelling outlets of the ink jet head along the sub scanning direction, when coating the droplets according to a droplet arrangement pattern constituted by a plurality of lattice points that correspond to positions at which each of the plurality of droplets are to be arranged.
6. The nanoimprinting method as defined in claim 4 , wherein:
one of the A direction and the B direction is set as a main scanning direction in the ink jet method, and the other is set as a sub scanning direction in the ink jet method; and
the ink jet head is set such that the intervals among lattice points along the sub scanning direction is an integer multiple of effective intervals among ink expelling outlets of the ink jet head along the sub scanning direction, when coating the droplets according to a droplet arrangement pattern constituted by a plurality of lattice points that correspond to positions at which each of the plurality of droplets are to be arranged.