Method for transferring a predetermined pattern reducing proximity effects
View Patent ↗A method for transferring a predetermined pattern onto a flat support performed by direct writing by means of a particle beam comprises at least: deposition of a photoresist layer on a free surface of the support, application of the beam on exposed areas of the photoresist layer, performing correction by modulation of exposure doses received by each exposed area, developing of the photoresist layer so as to form said pattern. Correction further comprises determination of a substitution pattern ( 11 ) comprising at least one subresolution feature and use of the substitution pattern ( 11 ) for determining the areas to be exposed when the electron beam is applied. In addition, modulation takes account of the density of the substitution pattern ( 11 ) near to each exposed area.
1. Method for transferring a desired pattern onto a support by direct writing by means of a particle or photon beam, comprising:
depositing a photoresist layer on the support,
defining a substitution pattern comprising at least one subresolution feature located such that the substitution pattern defines an area of the photoresist layer scanned by the beam smaller than the desired pattern;
exposing the photoresist layer with the beam according the substitution pattern instead of the desired pattern, using an exposure dose for the beam modulated according to the density of the substitution pattern; and
developing of the photoresist layer to form the desired pattern.
2. Method according to claim 1 , wherein the area of the photoresist layer scanned by the beam is comprised of the substitution pattern.
3. Method according to claim 2 , wherein at least one portion of the desired pattern is replaced, in the substitution pattern, by a set of at least two separate subresolution features, parallel to a longitudinal axis of the at least one portion.
4. Method according to claim 2 , wherein the substitution pattern is formed by the desired pattern during a first application period of the beam, then, during a second application period of the beam, by at least one subresolution feature, parallel to a longitudinal axis of a portion of the desired pattern and having a length equal to a length of the portion.
5. Method according to claim 4 , wherein the subresolution feature is superposed on the longitudinal axis of the portion.
6. Method according to claim 4 , wherein, during the second period, the substitution pattern associated with the portion is formed by a set formed by two separate subresolution features, symmetrical with respect to the longitudinal axis of the portion, a width of the set being equal to a width of the portion, after transfer.
7. Method according to claim 1 , wherein the area of the photoresist layer scanned by the beam is comprised of a complement of the substitution pattern.
8. Method according to claim 7 , wherein the substitution pattern is formed by a complement of the desired pattern, completed by subresolution features arranged outside a portion of the complement of the desired pattern, parallel to a longitudinal axis of the portion and having a length smaller than or equal to a length of the portion.
9. Method according to claim 8 , wherein at least one of the number and width of each subresolution feature, the distance between a subresolution feature and the portion, and the width of the portion are determined according to the width of an area of the desired pattern adjacent to the portion.
10. Method according to claim 1 , wherein direct writing is performed by lithography.
11. Method according to claim 1 , wherein the particle beam is selected from the group consisting in an electron beam and an ion beam.