System and a method for improved crosshatch nanomachining of small high aspect three dimensional structures by creating alternating superficial surface channels
View Patent ↗This invention provides the user the ability to accurately nanomachine surfaces with reduced tip induced errors. Nanomaching has two types of errors, a first type of error is brought about by the tip's shape and its aspect ratio. A second type of error due to the tip's deflection as it works the material. Therefore, embodiments of the present invention minimizes tip deflection errors allowing allow high aspect Nano-bits to reliably and accurately nanomachine small high aspect three dimensional structures to repair and rejuvenate photomasks.
1. A method for repairing an area of a photomask using a nanomachining tip of an atomic force microscope, comprising:
(a) positioning the nanomachining tip over a beginning of a first cut proximate to a first boundary of the repair area;
(b) removing material from the surface of the photomask in a first cut direction until an end of the first cut is reached;
(c) lifting the nanomachining tip from the cut;
(d) positioning the nanomachining tip over a beginning of a subsequent cut adjacent to the end of the previous cut;
(e) removing material from the surface of the photomask in a direction that is parallel and opposite to the previous cut direction until an end of the subsequent cut is reached;
(f) repeating steps (c), (d) and (e) until a second boundary of the repair area is reached;
(g) positioning the nanomachining tip over a beginning of a first orthogonal cut adjacent to the first boundary of the repair area;
(h) removing material from the surface of the photomask in a first orthogonal cut direction until an end of the first orthogonal cut is reached;
(i) lifting the nanomachining tip from the orthogonal cut;
(j) positioning the nanomachining tip over a beginning of a subsequent orthogonal cut adjacent to the end of the previous orthogonal cut;
(k) removing material from the surface of the photomask in a direction that is parallel and opposite to the previous orthogonal cut direction until an end of the subsequent orthogonal cut is reached;
(l) repeating steps (i), (j) and (k) until the second boundary of the repair area is reached.
2. The method according to claim 1 , wherein the end of the subsequent cut is proximate to the beginning of the previous cut.
3. The method according to claim 2 , wherein the end of the subsequent orthogonal cut is proximate to the beginning of the previous orthogonal cut.
4. The method according to claim 3 , wherein the end of the first orthogonal cut is proximate to the end of the first cut.
5. The method according to claim 4 , wherein the cut depth is less than 30 nanometers.
6. The method according to claim 1 , wherein, after the completion of step (l), an orthogonal series of isolated cuts defines the repair area.
7. The method according to claim 6 , wherein, after the completion of step (l), a grid of isolated pillars is disposed within the repair area.
8. The method according to claim 7 , further comprising:
(m) repeating steps (a) through (l) to smooth out the grid of isolated pillars.
9. The method according to claim 8 , further comprising immediately prior to step (m), replacing the nanomachining tip with a nanomachining tip having a different aspect ratio.
10. The method according to claim 1 , further comprising:
(m) repeating steps (a) through (l) at increasing cut depths until a desired depth is achieved.
11. The method according to claim 1 , further comprising:
prior to step (a), (1) creating a repair area perimeter.
12. The method according to claim 11 , wherein step (1) includes:
positioning the nanomachining tip over a beginning of a first perimeter cut proximate to a third boundary of the repair area;
removing material from the surface of the photomask in a first perimeter cut direction until an end of the first perimeter cut is reached;
lifting the nanomachining tip from the first perimeter cut;
positioning the nanomachining tip over a beginning of a second perimeter cut proximate to the first boundary of the repair area;
removing material from the surface of the photomask in a direction that is parallel to the first perimeter cut direction until an end of the second perimeter cut is reached;
positioning the nanomachining tip over a beginning of a first orthogonal perimeter cut adjacent to the beginning of the second perimeter cut;
removing material from the surface of the photomask in a first orthogonal perimeter cut direction until an end of the first orthogonal perimeter cut is reached;
lifting the nanomachining tip from the first orthogonal perimeter cut;
positioning the nanomachining tip over a beginning of a second orthogonal perimeter cut adjacent to the end of the second perimeter cut;
removing material from the surface of the photomask in a direction that is parallel to the first orthogonal perimeter cut direction until the end of the first perimeter cut is reached.
13. The method according to claim 11 , wherein step (1) includes:
positioning the nanomachining tip over a beginning of a first perimeter cut proximate to a third boundary of the repair area;
removing material from the surface of the photomask in a first perimeter cut direction until an end of the first perimeter cut is reached;
lifting the nanomachining tip from the first perimeter cut;
positioning the nanomachining tip over a beginning of a first orthogonal perimeter cut proximate to the end of the first perimeter cut;
removing material from the surface of the photomask in a direction that is orthogonal to the first perimeter cut direction until an end of the first orthogonal perimeter cut is reached;
positioning the nanomachining tip over a beginning of a second perimeter cut adjacent to the end of the first orthogonal perimeter cut;
removing material from the surface of the photomask in a second perimeter cut direction parallel and opposite to the first perimeter cut direction until an end of the second perimeter cut is reached;
lifting the nanomachining tip from the second perimeter cut;
positioning the nanomachining tip over a beginning of a second orthogonal perimeter cut adjacent proximate to the first boundary of the repair area;
removing material from the surface of the photomask in a direction that is parallel and opposite to the first orthogonal perimeter cut direction until the beginning of the first perimeter cut is reached.
14. The method according to claim 1 , wherein, in step (d), the beginning of the subsequent cut is 1 to 20 nanometers from the end of the previous cut.
15. The method according to claim 1 , wherein, in step (j), the beginning of the subsequent orthogonal cut is 1 to 20 nanometers from the end of the previous orthogonal cut.