Alternating aperture phase shift photomask having light absorption layer
View Patent ↗The present invention generally relates to optical lithography and more particularly relates to the fabrication of transparent or semitransparent phase shifting masks used in the manufacture of semiconductor devices. In particular, the present invention utilizes a light absorbing film in a conventional aaPSMs to balance the intensity of light through each opening of the photomask. The aaPSM of the present invention is used to make semiconductor devices or integrated circuits.
1. A method for manufacturing a semiconductor comprising the steps of:
interposing an alternating aperture phase shift photomask between a semiconductor wafer and an energy source, wherein said alternating aperture phase shift photomask comprises:
a substantially transparent substrate having at least one light transmitting opening formed therein;
a partially absorbing film layer covering portions of said substantially transparent substrate not defined by said at least one light transmitting opening; and
a patterned layer of opaque material affixed to said partially absorbing film, wherein said patterned layer exposes at least one portion of said underlying partially absorbing film layer, wherein said partially absorbing film layer comprises a thickness which substantially balances an aerial image intensity of light transmitted through said at least one partially absorbing opening with light transmitted through said at least one light transmitting opening;
generating energy in the energy source;
transmitting said generated energy through light transmitting opening in said substantially transparent substrate and said at least one exposed partially absorbing film layer; and
etching an image on said semiconductor wafer corresponding to said light transmitting opening in said substantially transparent substrate and said at least one exposed partially absorbing film layer.
2. The method of claim 1 , wherein said at least one exposed portion of said partially absorbing film alternates with said trench between opaque regions.
3. The method of claim 1 , wherein said partially absorbing layer is tuned to reduce the transmission of light through when exposed to an energy source.
4. The method of claim 1 , wherein said partially absorbing film is made from material selected from the group consisting of: MgF2, amorphous Si, Si3N4, SiON, CrO, CrON, TiN, TiO, TaO, TaN, MoO, MoN and MoON.
5. The method of claim 1 , wherein said partially absorbing film is made from material selected from the group consisting of an oxide, nitride, fluoride and oxynitride of a metallic element.
6. The method of claim 1 , wherein said substantially transparent substrate comprises quartz and said opaque layer comprises chromium.
7. A method for manufacturing a semiconductor comprising the steps of:
interposing an alternating aperture phase shift photomask between a semiconductor wafer and an energy source, wherein said alternating aperture phase shift photomask comprises:
a substantially transparent substrate;
a partially absorbing film layer having at least one opening formed therein,
wherein portions of said substantially transparent substrate underlying said opening in said partially absorbing film layer are exposed; and
a patterned layer of opaque material affixed to said partially absorbing film layer, said patterned layer of opaque material having at least one opening which exposes underlying portions of said partially absorbing film layer,
wherein said partially absorbing film layer comprises a thickness which substantially balances an aerial image intensity of light transmitted through said at least one opening in said opaque layer with light transmitted through at least one opening in said partially absorbing film layer;
generating energy in the energy source;
transmitting said generated energy through said at least one opening in said partially absorbing film layer and said at least one exposed portion of said partially absorbing film layer; and
etching an image on said semiconductor wafer corresponding to at least one opening in said partially absorbing film layer and said at least one exposed portion of said partially absorbing film layer.
8. The method of claim 7 , wherein said at least one exposed portion of said partially absorbing film layer alternates with said opening in said partially absorbing film layer.
9. The method of claim 7 , wherein said partially absorbing layer is tuned to reduce the transmission of light through when exposed to an energy source.
10. The method of claim 7 , wherein said partially absorbing film layer is made from material selected from the group consisting of: MgF2, amorphous Si, Si3N4, SiON, CrO, CrON, TiN, TiO, TaO, TaN, MoO, MoN and MoON.
11. The method of claim 7 , wherein said partially absorbing film layer is made from material selected from the group consisting of an oxide, nitride, fluoride and oxynitride of a metallic element.
12. The method of claim 7 , wherein said substantially transparent substrate comprises quartz and said opaque layer comprises chromium.