Method of patterning photoresist on a wafer using an attenuated phase shift mask
View Patent ↗An attenuated phase shift mask ( 10 or 20 ) includes a substrate ( 12 or 22 ) and an attenuation stack ( 11 or 21 ) overlying the substrate. The attenuation stack includes a chromium layer or ruthenium layer ( 14 or 24 ) overlying the substrate, a tantalum silicon oxide layer ( 16 or 26 ) overlying the chromium layer or the ruthenium layer, and a tantalum silicon nitride layer ( 18 or 28 ) overlying the tantalum silicon oxide layer. The attenuation stack may also include a layer ( 30 ) between the substrate ( 22 ) and the chromium or ruthenium layer ( 24 ). In one embodiment, this layer is a portion of the substrate. The attenuation stack is used to pattern photoresist ( 50 ) on a semiconductor wafer. In one embodiment, portions of the substrate adjacent the attenuation stack has a transmission of greater than 90 percent and the attenuation stack has a transmission of 5 to 20 percent at the exposure wavelength. In one embodiment, an inspection contrast between the substrate and the attenuation stack at an inspection wavelength is greater than 75 percent.
1. An attenuated phase shift mask, comprising:
a substrate; and
an attenuation stack overlying the substrate, wherein the attenuation stack comprises a first layer overlying the substrate, a tantalum silicon oxide layer overlying the first layer, and a tantalum silicon nitride layer overlying the tantalum silicon oxide layer, and wherein the first layer is one of a chromium layer or a ruthenium layer.
2. The attenuated phase shift mask of claim 1 , wherein the attenuation stack further comprises a second layer between the substrate and the first layer.
3. The attenuated phase shift mask of claim 2 , wherein the second layer is a portion of the substrate.
4. The attenuated phase shift mask of claim 3 , wherein the second layer is formed by removing portions of the substrate adjacent to the attenuation stack.
5. The attenuated phase shift mask of claim 1 , wherein portions of the substrate adjacent the attenuation stack has a transmission of greater than 90 percent at an exposure wavelength, and the attenuation stack has a transmission of 5 to 20 percent at the exposure wavelength.
6. The attenuated phase shift mask of claim 5 , wherein the first layer is doped to provide a reflection of less than 10 percent at the exposure wavelength.
7. The attenuated phase shift mask of claim 1 , wherein the first layer further comprises at least one of oxygen and nitrogen.
8. The attenuated phase shift mask of claim 1 , wherein an inspection contrast between the substrate and the attenuation stack at an inspection wavelength is greater than 75 percent.
9. A method for patterning photoresist on a wafer utilizing optical radiation, the method comprising:
providing an attenuated phase shift mask including a substrate and an attenuation stack overlying the substrate, the attenuation stack comprising a chromium layer or a ruthenium layer overlying the substrate, a tantalum silicon oxide layer overlying the chromium layer or the ruthenium layer, and a tantalum silicon nitride layer overlying the tantalum silicon oxide layer; and
patterning a photoresist layer on the wafer using the mask, wherein patterning comprises passing optical radiation through the attenuated phase shift mask to expose portions of the photoresist layer.
10. The method of claim 9 , wherein the optical radiation passing through the mask and exposing the photoresist layer has an exposure wavelength of at least 150 nanometers.
11. The method of claim 10 , wherein the optical radiation passing through portions of the substrate of the attenuated phase shift mask adjacent to the attenuation stack has a transmission of greater than 90 percent at the exposure wavelength and the optical radiation passing through the attenuated stack has a transmission of 5 to 20 percent at the exposure wavelength.
12. The method of claim 11 , wherein the attenuation stack provides a 180 degree phase shift of the optical radiation.
13. The method of claim 9 , wherein the attenuation stack further comprises a layer between the substrate and the chromium layer or the ruthenium layer.
14. The method of claim 13 , wherein the layer is a portion of the substrate.
15. The method of claim 14 , wherein the layer is formed by removing portions of the substrate adjacent to the attenuation stack.
16. The method of claim 9 , wherein the attenuation stack has a thickness of at most 1000 Angstroms.
17. The method of claim 9 , wherein the attenuation stack has a thickness of at most 700 Angstroms.
18. The method of claim 9 , wherein an inspection contrast between the substrate and the attenuation stack at an inspection wavelength is greater than 75 percent.
19. A method for patterning photoresist on a wafer utilizing optical radiation, the method comprising:
providing an attenuated phase shift mask including a substrate and an attenuation stack overlying the substrate, wherein the attenuation stack comprises a first layer, a second layer, and a third layer, wherein the first layer comprises one of chromium or ruthenium, the second layer comprises tantalum silicon oxide, and the third layer comprises tantalum silicon nitride; and
patterning a photoresist layer on the wafer using the mask, wherein patterning comprises passing optical radiation through the attenuated phase shift mask to expose portions of the photoresist layer.
20. The method of claim 19 , wherein the first and second layers are between the substrate and the third layer.
21. The method of claim 19 , wherein the second and third layers are between the substrate and the first layer.
22. The method of claim 19 , wherein portions of the substrate adjacent to the attenuation stack are removed to form a fourth layer of the attenuation stack.
23. The method of claim 22 , wherein the attenuation stack includes only the first, second, third, and fourth layers.
24. The method of claim 19 , wherein the attenuation stack includes only the first, second, and third layers.
25. The method of claim 19 , wherein the optical radiation passing through the mask and exposing the photoresist layer has a wavelength of at least 157 nanometers, and wherein the optical radiation passing through portions of the substrate of the attenuated phase shift mask adjacent to the attenuation stack has a transmission of greater than 90 percent and the optical radiation passing through the attenuated stack has a transmission of 5 to 20 percent.
26. The method of claim 25 , wherein the attenuation stack provides a 180 degree phase shift of the optical radiation.
27. The attenuated phase shift mask of claim 25 , wherein the first layer is doped to provide a reflection of less than 10 percent of the optical radiation.
28. The method of claim 19 , wherein the attenuation stack has a thickness of at most 1000 Angstroms.
29. The method of claim 19 , wherein an inspection contrast between the substrate and the attenuation stack at an inspection wavelength is greater than 75 percent.
30. The attenuated phase shift mask of claim 19 , wherein the first layer further comprises at least one of oxygen and nitrogen.