US 12,111,569 B2
Method for sizing a gray scale lithography mask
Ujwol Palanchoke, Grenoble (FR)
Assigned to COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES, Paris (FR)
Filed by COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES, Paris (FR)
Filed on Mar. 11, 2024, as Appl. No. 18/601,853.
Claims priority of application No. 2302191 (FR), filed on Mar. 9, 2023.
Prior Publication US 2024/0302737 A1, Sep. 12, 2024
Int. Cl. G03F 1/70 (2012.01)
CPC G03F 1/70 (2013.01) 14 Claims
 
1. A method for sizing a greyscale lithography mask, the mask mainly extending along a horizontal plane defined by a first direction and a second direction, the plane being perpendicular to a main direction of a light-exposing radiation of a photosensitive resin through the mask, the mask comprising a plurality of opaque zones to the radiation, each opaque zone being located in a zone of the mask called pixel, the plurality of opaque zones comprising first opaque zones being located in first pixels, the first pixels forming a first grating of the mask, the method comprising the following steps:
establishing a first target density D100* of a first surface density D100 of first opaque zones within the first grating, the first target density D100* being configured to enable the resin to be exposed to light over a first given target thickness e1* when the resin is exposed to radiation through the first mask grating, the first target thickness e1* being measured in the main direction of the radiation,
obtaining a first value, for the first target density D100*, of the derivative with respect to the first surface density D100 of a first thickness e1 over which the photosensitive resin is exposed to light, when it is exposed to a radiation through the first grating having the first surface density D100, said first value being referenced

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determining a first dimension Px,1 of the first pixels in the first direction, a first dimension Py,1 of the first pixels in the second direction, a first dimension Lx,1 of the first opaque zones in the first direction, a first dimension Ly,1 of the first opaque zones in the second direction, such that the value of an error over the first target thickness e1*, referenced MEEF(e1*), is less than
a first given threshold, MEEF(e1*) being calculated from the following formula:

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 with

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 being an error over Lx,1 and δLy,1 being an error over Ly,1,
using the dimensions obtained for the sizing of the first mask grating.