Use of a dual-tone resist to form photomasks including alignment mark protection, intermediate semiconductor device structures and bulk semiconductor device substrates
View Patent ↗An alignment mark mask element protects an underlying alignment mark during subsequent processing of a fabrication substrate. The alignment mark mask element is formed concurrent with formation of a photomask from a dual-tone photoresist that exhibits a pattern reversal upon exposure to an energy level. A portion of the dual-tone photoresist above the alignment mark is exposed to an energy sufficient to reverse a positive tone resist to a negative tone, which remains above the alignment mark after developing. The remainder of the dual-tone photoresist is exposed through a reticle at a lesser energy level and patterned to define aperture locations of a photomask for formation of semiconductor device features. In addition, a photomask for use on a fabrication substrate and an intermediate semiconductor device are disclosed. Methods of forming a photomask and an intermediate semiconductor device structure are also disclosed.
1. A photomask for use on a fabrication substrate, comprising:
a plurality of apertures located over at least a portion of a developed photoresist layer, wherein the plurality of apertures are configured to facilitate etching of an underlying material layer on a fabrication substrate; and
at least one alignment mark mask element formed of material of the developed photoresist layer and positioned to substantially shield only an underlying alignment mark on the fabrication substrate without shielding portions of the underlying material layer adjacent to the underlying alignment mark, wherein at least one of the plurality of apertures extends to a peripheral edge of the at least one alignment mark mask element.
2. The photomask of claim 1 , wherein the developed photoresist layer comprises a photoresist that is formulated to exhibit a pattern reversal from a positive tone to a negative tone.
3. The photomask of claim 1 , wherein the developed photoresist layer comprises a photoresist that is formulated to exhibit a pattern reversal related to an energy of radiation to which the photoresist is exposed.
4. The photomask of claim 1 , wherein the at least one alignment mark mask clement comprises a portion of a photoresist layer that has been reversed from a positive tone to a negative tone.
5. The photomask of claim 1 , wherein the at least one alignment mark mask element comprises a portion of the developed photoresist layer that has been reversed from a positive tone to a negative tone upon exposure to an energy of radiation of approximately 85 mJ.
6. The photomask of claim 1 , wherein the plurality of apertures comprises portions of the developed photoresist layer exposed to an energy of radiation of approximately 20 mJ.
7. The photomask of claim 1 , wherein a thickness of the at least one alignment mark mask element is related to energy to which the developed photoresist layer has been exposed.
8. An intermediate semiconductor device structure, comprising:
a fabrication substrate comprising at least one alignment mark;
at least one material layer over the fabrication substrate; and
a photomask over the at least one material layer, comprising:
apertures located over at least a portion of the photomask, wherein the apertures are configured to facilitate etching of the at least one material layer on the fabrication substrate; and
at least one alignment mark mask element formed of material of the photomask and positioned to substantially shield the at least one alignment mark without shielding portions of the at least one material layer adjacent to the at least one alignment mark, wherein at least one of the apertures extends to a peripheral edge of the at least one alignment mark mask element.
9. The intermediate semiconductor device structure of claim 8 , wherein the photomask comprises a photoresist material that is formulated to exhibit a pattern reversal from a positive tone to a negative tone.
10. The intermediate semiconductor device structure of claim 8 , wherein the photomask comprises a photoresist material that is formulated to exhibit a pattern reversal related to an energy of radiation to which the photoresist material is exposed.
11. The intermediate semiconductor device structure of claim 8 , wherein the at least one alignment mark mask element comprises a portion of the photomask formed of a photoresist material reversed from a positive tone to a negative tone.
12. The intermediate semiconductor device structure of claim 8 , wherein the at least one alignment mark mask element comprises a portion of the photomask formed of a photoresist material reversed from a positive tone to a negative tone upon exposure to a wavelength of radiation of approximately 85 mJ.
13. The intermediate semiconductor device structure of claim 12 , wherein a thickness of the at least one alignment mark mask element is related to an energy of radiation to which the portion of the photoresist material has been exposed to reverse the positive tone to the negative tone.
14. A semiconductor device structure, comprising:
a fabrication substrate comprising at least one alignment mark on a peripheral edge thereof;
at least one alignment mark mask clement comprising a photoresist material; and
at least one semiconductor device feature on the fabrication substrate, wherein the at least one semiconductor device feature abuts a peripheral edge of the at least one alignment mark, and wherein the at least one alignment mark mask element substantially shields the at least one alignment mark without shielding portions of the at least one semiconductor device feature abutting the peripheral edge of the at least one alignment mark.
15. A semiconductor device structure, comprising:
a bulk substrate fully populated with semiconductor die locations;
at least one alignment mark mask element comprising a photoresist material; and
at least one alignment mark located on a peripheral edge of the bulk substrate and residing within one of the semiconductor die locations, wherein the at least one alignment mark mask element substantially shields the at least one alignment mark without shielding portions of the semiconductor die locations adjacent to the at least one alignment mark.