Mask and method for using the mask in lithographic processing

• US 20050082559A1
• Filed: 10/15/2003
• Published: 04/21/2005
• Est. Priority Date: 10/15/2003
• Status: Active Grant

• Current Assignee: Polaris Innovations Limited (Wi-LAN Inc.)
• Original Assignee: Qimonda AG (Infineon Technologies AG)
• Inventors: Hasan Zaidi, Syed Shoaib, Williams, Gary, Gutmann, Alois
• Granted Patent: US 7,030,506 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• CPC Class Codes: G03F 9/7076 Mark details, e.g. phase grating mark, temporary mark
• CPC Class Codes: H01L 2223/54466 Located in a dummy or reference die
• CPC Class Codes: H01L 23/544 Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps test patterns for characterising or monitoring manufacturing processes H01L22/00
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]

Abstract

A method and mask to improve measurement of alignment marks is disclosed. An exemplary embodiment of the invention includes a resist mask with a patterned alignment mark comprising an assemblage of features whose spacing is smaller than the wavelength of light used to measure the alignment. In a preferred embodiment, an alignment mark patterning process alters the appearance of the alignment mark and renders an enhanced contrast with the substrate background.

Claims

1. A resist mask for measuring alignment, the resist mask comprising at least one alignment mark, wherein the alignment mark includes patterned structures at least some of whose lateral spacing is smaller than the wavelength of light used for alignment measurement.

2. The mask of claim 1, wherein the patterned structures further comprise a plurality of isolated resist features arranged to impart the desired size and shape of the alignment mark.

3. The mask of claim 2, wherein the patterned structures further comprise an array of features.

4. The mask of claim 2, wherein the patterned structures further comprise a stochastic assembly of features

5. The mask of claim 2, wherein the patterned structures appear rectangular in cross-section and top view.

6. The mask of claim 1, wherein the lateral spacing of the patterned structures is less than about half the wavelength of light used for alignment measurement.

7. The mask of claim 1, wherein the at least one alignment mark further includes a continuous resist layer upon which the patterned structures are formed.

8. The mask of claim 7, wherein the patterned structures further comprise an array of features.

9. The mask of claim 7, wherein the patterned structures further comprise an stochastic assembly of features.

10. The mask of claim 8, wherein the patterned structures appear rectangular in cross-section and top view.

11. The mask of claim 7, wherein the lateral spacing of the patterned structures is less than about half the wavelength of light used for alignment measurement.

12. A resist mask for measuring alignment, the resist mask comprising at least one alignment mark, wherein the alignment mark comprises at least two distinct regions, at least one distinct region formed from a plurality of patterned features, at least some of whose lateral spacing is smaller than the wavelength of light used for alignment measurement.

13. The mask of claim 12, wherein each region of the at least two distinct regions includes a characteristic spacing between features, the characteristic spacing differing between regions.

14. The mask of claim 13, wherein the patterned structures further comprise a plurality of isolated resist features arranged to impart the desired size and shape of the at least two distinct regions within the alignment mark.

15. The mask of claim 13, wherein the mark comprises two concentric regions, the outer region comprising a smaller characteristic feature spacing than the inner region.

16. The mask of claim 14, wherein the mark comprises two concentric regions, the outer region comprising a smaller characteristic feature spacing than the inner region.

17. A method for enhanced alignment measurement comprising:

(a) fabricating at least one permanent structure in a substrate, at least one structure comprising a permanent alignment mark;

(b) coating the substrate with resist;

(c) fabricating a resist mask on the substrate, including at least one resist alignment mark, wherein the mark is further divided into an assemblage of features, the spacing of the features being less than the wavelength of light used to measure alignment;

(d) placing the substrate containing the at least one alignment mark in an instrument for measuring the alignment; and

(e) measuring the relative position of the resist alignment mark and the permanent alignment mark.

18. The method of claim 17, wherein the fabrication of the resist mask is performed using optical lithography.

19. The method of claim 17, wherein the fabrication of the resist mask is performed using x-ray lithography.

20. The method of claim 17, wherein the fabrication of the resist mask is performed using electron beam lithography.