Venting of pellicle cavity for a mask
View Patent ↗The present invention describes a method of providing a substrate, the substrate being transparent to radiation at an actinic wavelength; forming an absorber layer over the substrate, the absorber layer including an active area and a peripheral area; removing the absorber layer from a portion of the peripheral area; and forming a trench in the substrate in the portion of the peripheral area. The present invention further describes a mask including an active area; and a peripheral area located around the active area, the peripheral area including vent channels.
1. A mask comprising:
an active area; and
a peripheral area disposed around said active area, said peripheral area comprising vent channels in a substrate, said vent channels including S-shaped curves and V-shaped cross-sections along their lengths.
2. The mask of claim 1 wherein said mask further comprises a frame disposed over said peripheral area, said frame traversing over said vent channels, and a pellicle disposed over said frame.
3. The mask of claim 2 wherein said vent channels allow gaseous exchange.
4. The mask of claim 2 wherein said vent channels allow pressure equalization.
5. The mask of claim 1 wherein said vent channels comprise trenches or grooves.
6. The mask of claim 1 wherein said active area includes a non-phase-shifting opening.
7. The mask of claim 1 wherein said active area includes a phase-shifting opening.
8. An apparatus comprising:
a mask, said mask comprising:
a non-phase-shifting opening disposed over a front surface of said mask in an absorber layer,
a phase-shifting opening disposed over said front surface of said mask in said absorber layer and an underlying substrate; and
a vent channel disposed over said front surface of said mask in said absorber layer and said underlying substrate, said venu channel including an S-shaped curve and a V-shaped cross-section along its length;
a frame mounted to said front surface of said mask, said frame enclosing an area that includes said non-phase-shifting opening and said phase-shifting opening, said frame traversing over said vent channel; and
a pellicle attached to said frame.
9. The apparatus of claim 8 wherein said mask is transmissive.
10. The apparatus of claim 8 wherein said vent channel allows gaseous exchange.
11. The apparatus of claim 8 wherein said vent channel allows pressure equalization.
12. The apparatus of claim 8 wherein said vent channel comprises a trench or a groove.
13. The apparatus of claim 8 further comprising a second frame, said second frame mounted to a back surface of said mask, and a second pellicle attached to said second frame.
14. The apparatus of claim 8 wherein said pellicle comprises a hard pellicle.
15. A phase-shifting mask comprising:
an active area disposed over a front surface of said phase-shifting mask;
a peripheral area disposed around said active area; and
vent channels disposed in a portion of said peripheral area in a substrate, said vent channels including S-shaped curves and V-shaped cross-sections along their lengths.
16. The phase-shifting mask of claim 15 wherein said vent channels are disposed in an absorber layer and an underlying substrate.
17. The phase-shifting mask of claim 15 wherein said vent channels comprises a depth of 500–1,500 microns, a width of 500–2,000 microns, and a length of 2,500–6,000 microns.
18. The phase-shifting mask of claim 15 further comprising:
a frame disposed over said portion of said peripheral area, said frame traversing over said vent channels; and
ap pellicle disposed over said frame.
19. The phase-shifting mask of claim 15 further comprising:
a second frame, said second frame disposed over a back surface of said phase-shifting mask; and
a second pellicle disposed over said second frame.