Pellicle having vent hole
A pellicle includes a frame having an attachment surface configured to attach to a photomask, wherein the frame comprises a vent hole. The pellicle further includes a filter covering the vent hole, wherein the filter directly contacts an inner surface of the frame, and the filter extends in a direction parallel to the attachment surface. The pellicle further includes a membrane extending over a top surface of the frame.
1 . A pellicle comprising:
a frame having an attachment surface configured to attach to a photomask, wherein the frame comprises a vent hole, and the vent hole comprises:
a first sidewall formed by the frame, wherein the first sidewall is angled with respect to the attachment surface;
a filter covering the vent hole, wherein the filter directly contacts an inner surface of the frame, and the filter extends in a direction parallel to the attachment surface; and
a membrane extending over a top surface of the frame.
2 . The pellicle of claim 1 , wherein the vent hole further comprises:
a second sidewall formed by the frame, wherein the second sidewall is parallel to the attachment surface.
3 . The pellicle of claim 2 , wherein the first sidewall is adjacent to an outer surface of the frame.
4 . The pellicle of claim 1 , wherein the filter is adjacent to the first sidewall.
5 . The pellicle of claim 1 , further comprising an adhesive between the membrane and the frame.
6 . The pellicle of claim 1 , wherein the membrane has a total thickness variation (TTV) of less than 10 nanometers (nm).
7 . The pellicle of claim 1 , wherein the membrane comprises multiple layers.
8 . The pellicle of claim 1 , wherein an innermost surface of the frame is perpendicular to the attachment surface.
9 . The pellicle of claim 8 , wherein the filter is outward of the innermost surface of the frame.
10 . An assembly comprising:
a photomask;
a frame having an attachment surface attached to the photomask, wherein the frame comprises a vent hole;
a filter covering the vent hole, wherein the filter directly contacts an inner surface of the frame, and the filter extends along a surface of the frame outside the vent hole, and the surface is parallel to the photomask; and
a membrane extending over a top surface of the frame.
11 . The assembly of claim 10 , wherein the filter is recessed into the frame.
12 . The assembly of claim 10 , wherein the filter is spaced from the photomask in a direction perpendicular to the photomask.
13 . The assembly of claim 10 , wherein a height of the frame positions the membrane out of focus of radiation passing through the membrane to pattern a surface of a wafer.
14 . The assembly of claim 10 , wherein the attachment surface extends below the filter.
15 . The assembly of claim 10 , wherein the vent hole comprises:
a first portion parallel to the attachment surface; and
a second portion angled with respect to the attachment surface.
16 . The assembly of claim 15 , wherein the filter is adjacent to the second portion.
17 . The assembly of claim 15 , wherein the first portion is adjacent to an outer surface of the frame.
18 . The assembly of claim 10 , wherein the membrane has a thickness of less than 50 nanometers (nm).
19 . A method comprising:
attaching a frame having an attachment surface to the photomask, wherein the frame comprises a vent hole, and the vent hole comprises a first sidewall formed by the frame, wherein the first sidewall is angled with respect to the attachment surface;
filtering particles, using a filter, to reduce the particles from an ambient environment reaching the photomask, wherein the filter covers the vent hole, and the filter directly contacts an inner surface of the frame;
positioning a membrane extending over a top surface of the frame out of focus of radiation passing through the membrane; and
patterning a wafer using the radiation.
20 . The method of claim 19 , further comprising removing the membrane from the frame.