Photolithographic mask having half tone main features and perpendicular half tone assist features
View Patent ↗A photolithographic mask having half tone main features and perpendicular half tone assist features. One embodiment provides for the exposure of radiation-sensitive resist layers on semiconductor substrates. The mask has at least one radiation-transmissive substrate and at least one half-tone layer. The half-tone layer is used to provide main features, the main features being formed in such a way that the pattern formed by the main features is transferred into the resist layer when irradiated, and the half-tone layer is also used to provide assist features, the assist features being formed substantially perpendicular to the main features in such a way that the pattern formed by the assist features is not transferred into the resist layer when irradiated.
1. A photolithographic mask for the exposure of a radiation-sensitive resist layer on a semiconductor substrate, the photolithographic mask comprising:
at least one radiation-transmissive substrate, at least one radiation-opaque layer, and at least one half tone layer,
the radiation-opaque layer and the at least one half-tone layer being used to provide main features, the main features being formed in such a way that the pattern formed by the main features is transferred into the resist layer when irradiated; and
the radiation-opaque layer and the at least one half-tone layer are used to provide assist features, the assist features being formed in such a way that the pattern formed by the assist features is not transferred into the resist layer when irradiated,
wherein for one main feature, which is oriented in a first direction at least in the region of a partial piece, there are at least two assist features, which, adjacent to the partial piece, are oriented in a second direction which is substantially perpendicular to the first direction,
wherein a distance x of the assist features from the main features lies in the range λ/(5 NA)<x<2λ/(3 NA).
2. The photolithographic mask of claim 1 , wherein between two directly adjacent main features, which at least in the region of a partial piece are oriented substantially parallel in a first direction, there are at least two assist features, which are oriented in a second direction substantially perpendicular to the first direction.
3. The photolithographic mask of claim 1 , wherein the assist features are rectangular in shape.
4. The photolithographic mask of claim 1 , wherein the assist features are composed of triangular shapes.
5. The photolithographic mask of claim 1 , wherein a width b of the assist features lies in the range λ/(10 NA)<b<λ/(3 NA).
6. The photolithographic mask of claim 1 , wherein a distance D between the main features lies in the range λ/(2 NA)<D<3λ/NA.
7. The photolithographic mask of claim 1 , wherein a distance d between the assist features lies in the range λ/(3 NA)<d<3λ/(2 NA).
8. The photolithographic mask of claim 1 , wherein for one main feature, which is oriented in a first direction at least in the region of a partial piece, there are at least four assist features, which, adjacent to the partial piece, are oriented in a second direction substantially perpendicular to the first direction.
9. The photolithographic mask of claim 1 , wherein a ratio of length to width of each of the main features is greater than 2.
10. A photolithographic mask for the exposure of a radiation-sensitive resist layer on a semiconductor substrate, the photolithographic mask comprising:
at least one radiation-transmissive substrate and at least one half tone phase shift layer used to transfer main features into the resist layer when irradiated;
the half tone phase shift layer used to provide assist features, such that the pattern formed by the assist features is not transferred into the resist layer when irradiated; and
where for one main feature, which is oriented in a first direction at least in the region of a partial piece, there are at least two assist features, which, adjacent to the partial piece, are oriented in a second direction which is substantially perpendicular to the first direction; and
wherein a distance x of the assist features from the main features lies in the range λ/(5 NA)<x<2λ/(3 NA).
11. The photolithographic mask of claim 10 , wherein between two directly adjacent main features, which at least in the region of a partial piece are oriented substantially parallel in a first direction, there are at least two assist features, which are oriented in a second direction substantially perpendicular to the first direction.
12. The photolithographic mask of claim 10 , wherein the assist features are rectangular in shape.
13. The photolithographic mask of claim 10 , wherein the assist features are composed of triangular shapes.
14. The photolithographic mask of claim 10 , wherein a width b of the assist features lies in the range λ/(10 NA)<b<λ/(3 NA).
15. The photolithographic mask of claim 10 , wherein for one main feature, which is oriented in a first direction at least in the region of a partial piece, there are at least four assist features, which, adjacent to the partial piece, are oriented in a second direction substantially perpendicular to the first direction.
16. The photolithographic mask of claim 10 , wherein a distance D between the main features lies in the range λ/(2 NA)<D<3λ/NA.
17. The photolithographic mask of claim 16 , wherein a distance d between the assist features lies in the range λ/(3 NA)<d<3λ/(2 NA).
18. The photolithographic mask of claim 17 , wherein a ratio of length to width of the main feature is greater than 2.