Method of forming three-dimensional lithographic pattern

Abstract

A method of forming a three-dimensional lithographic pattern is provided. The method includes providing a substrate. A first photoresist layer is formed on the substrate. The first photoresist layer corresponds to a first exposure removal dose. A second photoresist layer is formed on the first photoresist layer. The second photoresist layer corresponds to a second exposure removal dose, which is different from the first exposure removal dose. A reticle with multiple regions of different light transmittances is provided. Through the reticle, the first and second photoresist layers are exposed to form a first removable region in the first photoresist layer and a second removable region in the second photoresist layer. The second removable region is different from the first removable region. The first and second photoresist layers are then developed to remove the first and second removable regions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 illustrates a cross-sectional view of a substrate with two photoresist layers in accordance with one embodiment of the present invention;

FIG. 2A illustrates a cross-sectional view of exposing the substrate of FIG. 1 through a reticle in accordance with one embodiment of the present invention;

FIG. 2B illustrates a cross-sectional view of removing removable regions of FIG. 2A;

FIG. 3A illustrates a cross-sectional view of exposing the substrate of FIG. 1 through a reticle in accordance with another embodiment of the present invention; and

FIG. 3B illustrates a cross-sectional view of removing removable regions of FIG. 3A.

Claims

1. A method of forming a three-dimensional lithographic pattern, comprising: providing a substrate;forming a first photoresist layer on said substrate, said first photoresist layer corresponding to a first exposure removal dose;forming a second photoresist layer on said first photoresist layer, said second photoresist layer corresponding to a second exposure removal dose different from said first exposure removal dose;providing a reticle with multiple regions of different light transmittances;through said multiple regions of different light transmittances of said reticle, exposing said first photoresist layer and said second photoresist layer so as to form a first removable region in said first photoresist layer and a second removable region in said second photoresist layer, respectively, wherein said second removable region is different from said first removable region; anddeveloping said first photoresist layer and said second photoresist layer so as to remove said first removable region and said second removable region.

2. The method of claim 1, wherein said substrate comprises a semiconductor substrate or an incomplete semiconductor device.

3. The method of claim 1, wherein said reticle comprises a transparent substrate, a high light transmittance layer, and an opaque layer to constitute said multiple regions of different light transmittances.

4. The method of claim 1, wherein said first exposure removal dose is higher than said second exposure removal dose.

5. The method of claim 4, wherein said step of exposing comprises a step of exposing with an exposure energy substantially equal to or higher than said first exposure removal dose.

6. The method of claim 5, wherein said step of exposing comprises a step of modulate said exposure energy through one of said multiple regions of different light transmittance so that said modulated energy is substantially equal to or higher than said second exposure removal dose and less than said first exposure removal dose to form said second removable region substantially only in said second photoresist layer.

7. The method of claim 1, wherein said step of exposing comprises forming a removable region in said second photoresist layer, and said removable region overlaps said first removable region and is adjacent to said second removable region.

8. The method of claim 7, wherein said first removable region, said second removable region, and said removable region constitute a three-dimensional pattern comprising a dual damascene pattern or a bottle-like pattern.

9. A method of forming a dual damascene pattern, comprising: providing a substrate;forming a first photoresist layer on said substrate, said first photoresist layer corresponding to a first exposure removal dose;forming a second photoresist layer on said first photoresist layer, said second photoresist layer corresponding to a second exposure removal dose smaller than said first exposure removal dose;providing a reticle with multiple regions of different light transmittances;through said reticle, exposing said first photoresist layer and said second photoresist layer so as to form a first removable region in said first photoresist layer and a removable region in said second photoresist layer through one of said multiple regions of different light transmittances and to form a second removable region substantially only in said second photoresist layer through another one of said multiple regions of different light transmittances, respectively;developing said first photoresist layer and said second photoresist layer so as to remove said first removable region, said second removable region, and said removable region to form a patterned photoresist; andetching said substrate to form said patterned dual damascene pattern in said substrate by using said patterned photoresist as a mask.

10. The method of claim 9, wherein said substrate comprise a semiconductor substrate or an incomplete semiconductor device.

11. The method of claim 9, wherein said reticle comprises a transparent substrate, a high light transmittance layer, and an opaque layer to constitute said multiple regions of different light transmittances.

12. The method of claim 9, wherein said step of exposing comprises a step of exposing with an exposure energy substantially equal to or higher than said first exposure removal dose.

13. The method of claim 12, wherein said step of exposing comprises a step of modulate said exposure energy through said another one of said multiple regions of different light transmittance so that said modulated energy is substantially equal to or higher than said second exposure removal dose and less than said first exposure removal dose to form said second removable region substantially only in said second photoresist layer.

14. The method of claim 9, wherein said removable region overlaps said first removable region and is adjacent to said second removable region.