APPARATUS AND METHODS FOR DETECTING OVERLAY ERRORS USING SCATTEROMETRY

• US 20080049226A1
• Filed: 10/29/2007
• Published: 02/28/2008
• Est. Priority Date: 12/05/2002
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Fabrikant, Anatoly, Levy, Ady, Adel, Michael, Friedmann, Michael, Smith, Ian, Golovanesky, Boris, Mieher, Walter
• Granted Patent: US 7,564,557 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 single metrology tool, comprising:

a scatterometry overlay measurement system configured to measure overlay on a combined mark having a scatterometry overlay target disposed over a scatterometry CD or profile target; and

a CD-SEM system configured to measure critical dimension on the CD or profile target of the combined mark.

2. The tool as recited in claim 1, wherein the scatterometry overlay measurement system is configured to measure overlay on both the scatterometry overlay target and the scatterometry CD or profile target based on a scatterometry overlay technique without using calibration or a model regression technique, wherein the scatterometry overlay technique is a phase based technique that includes representing each measured optical signal as a set of periodic functions having a plurality of known parameters and an unknown overlay error parameter and analyzing the set of periodic functions to solve for the unknown overlay error parameter to thereby determine the overlay error.

3. The tool as recited in claim 1 further including a robotic handling system configured to transfer work pieces between stations of the single metrology tool.

4. The tool as recited in claim 3 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.

5. The tool as recited in claim 3 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.

6. The tool as recited in claim 1, wherein the combined 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 mark being formed in the first layer and a second layer, wherein the scatterometry mark in the first layer comprises the scatterometry CD or profile target in the first layer.

7. The tool as recited in claim 5, wherein the CD-SEM system is configured to measure critical dimension on the CD or profile target after formation of patterns in the first layer, and wherein the scatterometry overlay measurement system is configured to measure overlay after the formation of patterns in the second layer.

8. A scatterometry mark configured for determining overlay error and CD or profile 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 and are arranged for determining the CD or profile error.

9. A target as recited in claim 8, 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 are inhibited from significantly affecting the measured optical signals.

10. A target structure for measuring overlay between a second periodic structure and a third periodic structure both disposed above a first grating for determining a CD or profile error, wherein 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.

11. The target structure of 10 wherein the second periodic structure is a line grating.

12. The target structure of 10 wherein the third periodic structure is a line grating.

13. The target structure of 12 wherein the first periodic structure is a line grating comprised of copper damascene materials.