Inspection method for thin film stack

• US 20080219409A1
• Filed: 02/14/2008
• Published: 09/11/2008
• Est. Priority Date: 03/09/2007
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ueda, Kazuhiro
• Granted Patent: US 7,724,872 B2
• Time in Patent Office: Days
• US Class Current: 378/89
• CPC Class Codes: G01B 15/02 for measuring thickness

Abstract

An X-ray reflectivity measuring method is provided to measure and inspect, with higher accuracy, film thickness of a thin film stack as a sample where a thick film is provided on the thin film stack. This X-ray reflectivity measuring method can measure X-ray reflectivity of the thin film stack embedded within a thick film by applying the X-ray focused to ⅓ or less the thickness of a thick film on the thin film stack to an end surface of the thick film, transmitting the X-ray through the thick film, thereafter applying the X-ray to the thin film stack, transmitting again the reflected X-ray to the thick film, and then extracting the reflection X-ray from the end surface in the opposite side of the incident surface and also can inspect film thickness of the thin film stack embedded in the thick film with the Fourier transformation method and the minimum square analysis method with the theoretical curve.

Claims

1. An inspection method for a thin film stack, comprising the steps of:

placing a substrate, on which a stack formed by stacking a plurality of thin films is provided, on a sample board;

applying an X-ray from a side surface of the stack in the direction crossing the thin film laminating direction;

changing an incident angle (θ

) of the X-ray to the side surface of the stack or wavelength of the incident X-ray to measure dependence on incident angle of reflectivity of the X-ray reflected from the stack or dependence on wavelength of the X-ray;

acquiring a curve indicating dependence on scattering vector of the X-ray reflectivity by converting the incident angle or the X-ray wavelength to a scattering vector;

q=(4π

/λ

)sin θ

; and

obtaining film thickness of the stack with the minimum square analysis method of a measured reflectivity curve obtained from dependence on scattering vector of the X-ray reflectivity and a theoretical reflectivity curve derived theoretically.

2. The inspection method for a thin film stack according to claim 1, wherein a shape of the X-ray beam incident to the stack is 10 μ

m or less in a short side or a short diameter at a position of the stack placed on the sample board.

3. The inspection method for a thin film stack according to claim 2, wherein thickness of thin films stacked into a stack is three times or more but is 15 times or less the short side or short diameter of the incident X-ray beam at the position of the stack placed on the sample board.

4. The inspection method for a thin film stack according to claim 2, wherein a solution layer having the thickness equal to three times or more but is equal to 15 times or less the short side or short diameter of the incident X-ray beam at the position of the stack placed on the sample board.

5. The inspection method for a thin film stack according to claim 2, wherein thickness of the stack in the transmitting direction of the X-ray is 100 times or more but is 2 mm or less the short side or short diameter of the X-ray incident to the stack.

6. An inspection method for a thin film stack, comprising the steps of:

placing a substrate, on which a stack that is formed by stacking a plurality of thin films is provided, on a sample board;

applying an X-ray to a side surface of the stack crossing the thin film stacking direction;

measuring dependence on incident angle of the X-ray or dependence on wavelength of the X-ray reflected from the stack by varying an incident angle (θ

) of the X-ray to the side surface of the stack or wavelength of the X-ray;

acquiring dependence on scattering vector of the X-ray reflectivity by converting the incident angle or wavelength of the X-ray to the scattering vector;

q=(4π

/λ

)sin θ

; and

obtaining thickness of thin films of the stack from the Fourier peak obtained by Fourier transformation of the measured reflectivity curve obtained from dependence on scattering vector of the X-ray reflectivity.

7. The inspection method for a thin film stack according to claim 6, wherein a shape of the X-ray beam incident to the stack is 10 μ

m or less in a short side or a short diameter at the position of the stack placed on the sample board.

8. The inspection method for thin a film stack according to claim 7, wherein thickness of a thin film stacked into the stack is three times or more but 15 times or less a short side or a short diameter of the incident X-ray beam at the position of the stacked placed on the sample board.

9. The inspection method for a thin film stack according to claim 7, wherein a solution layer, having thickness of three times or more but 15 times or less a short side or a short diameter of the incident X-ray beam at the position of the stack placed on the sample board, is provided on the stack.

10. The inspection method for a thin film stack according to claim 7, wherein thickness of the stack in the X-ray transmitting direction is 100 times or more but 2 mm or less a short side or a short diameter of the X-ray incident to the stack.