PELLICLE FOR USE IN A MICROLITHOGRAPHIC EXPOSURE APPARATUS
A pellicle for use in microlithographic exposure apparatus ( 10 ) has, for an operating wavelength of the apparatus, a maximum transmittance for light rays ( 56 ) that obliquely impinge on the pellicle ( 34; 134; 234 ). This ensures smaller variations of the transmittance over a broad range of angles of incidence, as it occurs in very high numerical aperture projection lenses.
1 - 24 . (canceled)
25 . A pellicle, comprising:
a membrane; and
an anti-reflective coating applied to the membrane,
wherein the membrane and the anti-reflective coating are designed such that, for an operating wavelength of the microlithographic exposure apparatus, the transmittance of the pellicle varies by less than 2% for angles of incidence between 0° and 15°, and where the pellicle is designed to be in a microlithographic exposure apparatus.
26 . The pellicle of claim 25 , wherein the transmittance of the pellicle varies by less than 2% for angles of incidence between 0° and 25°.
27 . The pellicle of claim 26 , wherein the transmittance of the pellicle varies by less than 1% for angles of incidence between 0° and 25°.
28 . An apparatus, comprising:
a) an illumination system configured to produce projection light,
b) a projection lens configured to image a pattern contained in a mask onto a light sensitive layer, and
c) a pellicle that has, for the projection light, a transmittance maximum for light rays that impinge on the pellicle with angles of incidence between 2° and the maximum angle of incidence with respect to the pellicle that may occur during operation of the apparatus,
wherein the apparatus is a microlithographic projection exposure apparatus.
29 . The apparatus of claim 28 , wherein the transmittance maximum is a global or a local maximum.
30 . The apparatus of claim 28 , wherein the pellicle has a mean transmittance that is greater than 95%, wherein the mean is taken over all angles of incidence with respect to the pellicle that may occur during operation of the apparatus.
31 . The apparatus of claim 30 , wherein the mean transmittance is greater than 98%.
32 . The apparatus of claim 28 , wherein the pellicle has a transmittance that varies by less than 5% over all angles of incidence with respect to the pellicle that may occur during operation of the apparatus.
33 . The apparatus of claim 32 , wherein the transmittance varies by less than 2.5%.
34 . The apparatus of claim 28 , wherein angles of incidence between 0° and arcsin(NA o ) occur during operation of the apparatus, wherein NA o is the object side numerical aperture of the projection lens.
35 . (canceled)
36 . (canceled)
37 . The apparatus of claim 28 , wherein angles of incidence between 0° and 25° occur during operation of the projection exposure apparatus.
38 . (canceled)
39 . The apparatus of claim 28 , wherein the pellicle comprises a membrane that is not covered by an anti-reflection coating.
40 . The apparatus of claim 28 , wherein the pellicle comprises a membrane and an anti-reflective coating applied to the membrane.
41 . The apparatus of claim 40 , wherein the anti-reflective coating is designed such that the transmittance maximum is achieved for different operating wavelengths.
42 . The apparatus of claim 28 , wherein the projection lens is designed for immersion operation in which an immersion liquid covers the photosensitive layer.
43 . The apparatus of claim 28 , wherein the transmittance of the pellicle continuously increases with growing angle of incidence until a transmittance maximum is reached.
44 . The apparatus of claim 43 , wherein the projection lens is designed for immersion operation in which an immersion liquid covers the photosensitive layer, and wherein the transmittance increases in such a way that an absorption of oblique rays in the immersion liquid is at least substantially compensated for.
45 . The apparatus of claim 28 , comprising an absorptive filter element that is arranged in or in close proximity of a pupil plane of the projection lens, the filter element having a locally varying transmittance that is determined such that the dependency of the transmittance of the pellicle on the angle of incidence is at least substantially compensated for.
46 . The apparatus of claim 45 , wherein the locally varying transmittance is determined such that additionally the dependency of the transmittance of the immersion liquid on a second angle of incidence with respect to the light sensitive layer is at least substantially compensated for.
47 . The apparatus of claim 28 , comprising an absorptive filter element that is arranged in or in close proximity of a field plane of the projection lens, the filter element having an angularly varying transmittance that is determined such that the dependency of the transmittance of the pellicle on the angle of incidence is at least substantially compensated for.
48 . The apparatus of claim 47 , wherein the angularly varying transmittance is determined such that additionally the dependency of the transmittance of the immersion liquid on a second angle of incidence with respect to the light sensitive layer is at least substantially compensated for.
49 . The apparatus of claim 48 , wherein the filter element is interchangeably arranged in a filter holder.
50 . The apparatus of claim 49 , wherein the projection lens has an image side numerical aperture NA i >1.
51 . (canceled)
52 . An apparatus, comprising:
a) an illumination system configured to produce projection light,
b) a projection lens configured to image a pattern contained in a mask onto a light sensitive layer, and
c) a pellicle having a transmittance distribution such that a dependency of the transmittance of an immersion liquid on an angle of incidence with respect to the light sensitive layer is at least substantially compensated for,
wherein the apparatus is a microlithographic exposure apparatus.
53 . (canceled)
54 . (canceled)