Apparatus and methods for detecting overlay errors using scatterometry

• US 20040233443A1
• Filed: 02/23/2004
• Published: 11/25/2004
• Est. Priority Date: 02/22/2003
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Fabrikant, Anatoly, Levy, Ady, Friedmann, Michael, Smith, Ian, Adel, Michael E., Mieher, Walter D., Golovanesky, Boris
• Granted Patent: US 7,289,213 B2
• Time in Patent Office: Days
• US Class Current: 356/401
• CPC Class Codes: G01N 2021/213 Spectrometric ellipsometry
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
• 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 7/70683 Mark designs
• CPC Class Codes: G03F 9/7049 Technique, e.g. interferometric
• CPC Class Codes: G03F 9/7084 Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels
• CPC Class Codes: G03F 9/7088 Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection

Abstract

Disclose is a combined scatterometry mark comprising a scatterometry critical dimension (CD) or profile target capable of being measured to determine CD or profile information and a scatterometry overlay target disposed over the scatterometry CD or profile target, the scatterometry overlay target cooperating with the scatterometry CD or profile target to form a scatterometry mark capable of being measured to determine overlay.

Claims

1. A combined scatterometry mark, comprising:

a scatterometry critical dimension (CD) or profile target capable of being measured to determine CD or profile information; and

a scatterometry overlay target disposed over the scatterometry CD or profile target, the scatterometry overlay target cooperating with the scatterometry CD or profile target to form a scatterometry mark capable of being measured to determine overlay.

2. The combined scatterometry mark as recited in claim 1 wherein the combined scatterometry mark provides for both scatterometry CD or profile measurement and scatterometry overlay measurement at different steps in a wafer manufacturing process.

3. The combined scatterometry mark as recited in claim 1 wherein combined scatterometry mark is formed in at least two layers of a work piece, the scatterometry CD or profile target being formed in a first layer, and the scatterometry target being formed in a second layer.

4. The combined scatterometry mark as recited in claim 3 wherein the scatterometry CD or profile periodic targets are capable of being measured after formation of a first layer pattern, and wherein the scatterometry overlay mark is capable of being measured after the formation of a second layer pattern.

5. The combined scatterometry mark as recited in claim 3 wherein the scatterometry CD or profile periodic targets formed on the first layer include a first grating oriented in a first direction and a second grating oriented in a second direction, the second direction being orthogonal to the first direction, and wherein the scatterometry overlay target formed on the second layer include a first group of gratings and a second group of gratings, both the first and second groups of gratings including one or more gratings, the gratings in the first group are oriented in the first direction and the gratings in the second group are oriented in the second direction, the first group of gratings being positioned over the first grating of the CD or profile scatterometry target, the second group of gratings being positioned over the second grating of the CD or profile scatterometry target.

6. The combined scatterometry mark as recited in claim 5 wherein first and second groups of gratings each include four gratings.

7. A single metrology tool, comprising:

a scatterometry overlay measurement system configured to measure overlay; and

a CD-SEM system configured to measure critical dimension.

8. The tool as recited in claim 7 further including a robotic handling system configured to transfer work pieces between stations of the single metrology tool.

9. The tool as recited in claim 8 wherein the scatterometry overlay measurement system is integrated within the CD-SEM system such that the CD-SEM system and scatterometry overlay measurement system share at least a portion of the robotic wafer handling system.

10. The tool as recited in claim 8 wherein the CD-SEM system and the scatterometry overlay measurement system are separate system capable of independent operation, the systems being linked by at least a portion of the robotic wafer handling system.

11. A method of producing a combined critical dimension and overlay mark, comprising:

forming a CD target in a first layer of a sample; and

forming an overlay target in a second layer of the sample, the overlay target being formed over the CD target.

12. A method for determining CD in one layer and an overlay error between at least two layers in a multiple layer sample, the method comprising:

performing scatterometry measurements on a CD target in order to determine CD, the CD target being formed in a first layer of the sample; and

performing scatterometry measurements on an overlay mark in order to determine overlay error, the overlay mark comprising an overlay target formed in a second layer of the sample and the CD target formed in the first layer of the sample, the overlay target being disposed over the CD target.

13. The method as recited in claim 12 wherein the CD target is measured after formation of a first layer pattern, and wherein the overlay mark is measured after the formation of a second layer pattern.

14. The method as recited in claim 12 wherein the CD target formed on the first layer includes a first grating oriented in a first direction and a second grating oriented in a second direction, the second direction being orthogonal to the first direction, and wherein the overlay target formed on the second layer includes a first group of gratings and a second group of gratings, both the first and second groups of gratings including one or more gratings, the gratings in the first group are oriented in the first direction and the gratings in the second group are oriented in the second direction, the first group of gratings being positioned over the first grating of the CD target, the second group of gratings being positioned over the second grating of the CD target.

15. A method as recited in claim 12, wherein the overlay error is determined without comparing the measured optical signals to calibration data.

16. A scatterometry mark configured for determining overlay error, comprising:

a plurality of periodic targets that each have structures on a first and second layer, wherein there are predefined offsets between the first and second structures so that overlay error between the first and second structures may be determined by analyzing a plurality of measured optical signals from each target;

a plurality of targets that each have third structures on a third layer that is underneath the first and second layer, wherein the third structures are perpendicular to the first and second structures.

17. A target as recited in claim 16, wherein the third structures are formed from one or more materials that form a screen for lower structures beneath the third layer so that the lower structures from significantly affecting the measured optical signals.

18. A target structure for measuring overlay between a second periodic structure and a third periodic structure both disposed above a first line grating where the first grating is oriented in a first direction and the second and third periodic structure are oriented in a second direction, the second direction being substantially orthogonal to the first direction.

19. The target structure of 18 wherein the second periodic structure is a line grating.

22. A method of determining overlay error, comprising measuring the target structure of claim 19 with a scatterometry overlay technique to determine overlay error between the second and third periodic structures.

20. The target structure of 18 wherein the third periodic structure is a line grating.

21. The target structure of 19 wherein the first periodic structure is a line grating comprised of copper damascene materials.