System and method using visible and infrared light to align and measure alignment patterns on multiple layers

• US 20060115956A1
• Filed: 11/15/2005
• Published: 06/01/2006
• Est. Priority Date: 12/01/2004
• Status: Active Grant

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Augustyn, Walter H., Raval, Pankaj
• Granted Patent: US 7,365,848 B2
• Time in Patent Office: Days
• US Class Current: 438/401
• CPC Class Codes: G03F 9/7003 Alignment type or strategy, e.g. leveling, global alignment
• CPC Class Codes: G03F 9/7065 Production of alignment light, e.g. light source, control of coherence, polarization, pulse length, wavelength
• 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

A system and method are used to increase alignment accuracy of feature patterns through detection of alignment patterns on both a surface layer and at least one below surface layers of an object. Visible light is used to detect alignment patterns on the surface layer and infrared light is used to detect patterns one layers below the surface. For example, reflected visible light and transmitted infrared light are co-focused onto detector after impinging on respective alignment patterns. The co-focused light is then used to determine proper alignment of the object for subsequent pattern features. This substantially increases accuracy of alignment of pattern features between layers, as compared to conventional systems.

Claims

1. A system, comprising:

an alignment system including an illumination portion and a detector, the illumination portion producing at least visible and infrared light;

an object, including,

a surface layer including a first feature pattern and a first alignment pattern,

a support layer, and

a second layer, which is located between the surface layer and the support layer,

wherein at least one of the support layer and the second layer comprises a second feature pattern and a second alignment pattern; and

a focusing system that co-focuses on the detector the at least visible and infrared light after each has impinged on at least one of the first and second alignment patterns,

whereby the object is aligned to receive subsequent feature patterns based on the detected first and second alignment patterns.

2. The system of claim 1, wherein the focusing system comprises:

an optical system positioned between the object and the detector, wherein the optical system performs the co-focusing of the at least visible and infrared light onto the detector.

3. The system of claim 2, wherein the focusing system further comprises:

a positioning system that receives a signal from the alignment system corresponding to a measured value and that moves at least one of the object and the detector relative to the optical system based on the measured value, such that the at least visible and infrared light are co-focused on the detector.

4. The system of claim 2, wherein the optical system comprises an optical element including at least first, second, and third lenses.

5. The system of claim 4, wherein:

the first lens comprises R1=−

64 to −

65 mm, R2=−

71 to −

72 mm, thickness=1.5 to 1.6 mm, diameter, =22.0 mm, and a glass type is SF10 (Schott);

the second lens comprises R1=−

71 to −

72 mm, R2=15 to 16 mm, thickness=1 to 2 mm, diameter=22.0 mm, and a glass type is N-PSK3 (Schott); and

the third lens comprises R1=15 to 16 mm, R2=−

35 to −

36 mm, thickness=10 to 11 mm, diameter=22.0 mm, and a glass type is N-PK51 (Schott).

6. The system of claim 5, wherein:

the first lens comprises R1=−

64.795 mm, R2=−

71.120 mm, thickness=1.518 mm, diameter, =22.0 mm, and a glass type is SF10 (Schott);

the second lens comprises R1=−

71.120 mm, R2=15.469 mm, thickness=1.5 mm, diameter=22.0 mm, and a glass type is N-PSK3 (Schott); and

the third lens comprises R1=15.469 mm, R2=−

35.382 mm, thickness=10.083 mm, diameter=22.0 mm, and a glass type is N-PK51 (Schott).

7. The system of claim 2, wherein the optical system comprises an optical element including at least first and second lenses.

8. The system of claim 7, wherein:

the first lens comprises R1=−

26 to −

27 mm, R2=infinity, thickness=3 mm, diameter=12 to 13 mm, and a glass type is BK7 (Schott);

the second lens comprises R1=infinity, R2=−

59 to −

60 mm, thickness=5 mm, diameter=12 to 13 mm, and a glass type is F2 (Schott).

9. The system of claim 8, wherein:

the first lens comprises R1=−

26.697 mm, R2=infinity, thickness=3 mm, diameter=12.7 mm, and a glass type is BK7 (Schott);

the second lens comprises R1=infinity, R2=−

59.03 mm, thickness=5 mm, diameter=12.7 mm, and a glass type is F2 (Schott).

10. The system of claim 1, wherein:

the visible light is used to detect a position of the first alignment pattern; and

the infrared is used to detect a position of the second alignment pattern.

11. The system of claim 1, wherein:

the visible light is reflected from the first alignment pattern before being focused onto the detector using the focusing system; and

the infrared light is transmitted through the second alignment pattern before being focused onto the detector using the focusing system.

12. The system of claim 1, wherein:

the infrared light is generated from a first side of the object; and

the visible light is generated from a second side of the object, opposite the first side.

13. A method, comprising:

(a) generating at least visible light and infrared light;

(b) impinging the visible light onto a first alignment pattern on a surface layer of an object;

(c) focusing the impinged visible light onto a detector;

(d) impinging the infrared light onto a second alignment pattern on a second layer of the object, the second layer of the object being below the first layer of the object;

(e) focusing the impinged infrared light onto the detector;

(f) generating an alignment signal based on the detected first and second alignment patterns; and

(g) aligning the object to receive a subsequent portion of a feature pattern based on step (f).

14. The method of claim 13, wherein the visible and IR light are focused onto the detector substantially simultaneously.

15. The method of claim 13, wherein:

the visible light is reflected from the first alignment pattern before being focused onto the detector; and

the infrared light is transmitted through the second alignment pattern before being focused onto the detector.

16. The method of claim 13, wherein:

the infrared light is generated from a first side of the object; and

the visible light is generated from a second side of the object, opposite the first side.

17. A flat panel display formed using the method of claim 13.

18. An integrated circuit formed using the method of claim 13.