SHAPE MEASUREMENT APPARATUS AND METHOD

• US 20100295941A1
• Filed: 05/21/2010
• Published: 11/25/2010
• Est. Priority Date: 05/21/2009
• Status: Active Grant

• Current Assignee: Koh Young Technology Inc.
• Original Assignee: Koh Young Technology Inc.
• Inventors: KIM, Min-Young, LEE, Seung-Jun, JEONG, Joong-Ki
• Granted Patent: US 9,275,292 B2
• Time in Patent Office: Days
• US Class Current: 348/135
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G01B 11/2531 using several gratings, projected with variable angle of incidence on the object, and one detection device
• CPC Class Codes: G01B 11/254 Projection of a pattern, viewing through a pattern, e.g. moiré
• CPC Class Codes: G01N 2021/95638 for PCB's

Abstract

A shape measurement apparatus includes a work stage supporting a target substrate, a pattern-projecting section including a light source, a grating part partially transmitting and blocking light generated by the light source to generate a grating image and a projecting lens part making the grating image on a measurement target of the target substrate, an image-capturing section capturing the grating image reflected by the measurement target of the target substrate, and a control section controlling the work stage, the pattern-projecting section and the image-capturing section, calculating a reliability index of the grating image and phases of the grating image, which is corresponding to the measurement target, and inspecting the measurement target by using the reliability index and the phases. Thus, the accuracy of measurement may be enhanced.

Claims

1. A shape measurement apparatus, comprising:

a work stage supporting a target substrate;

a pattern-projecting section comprising a light source, a grating part transmitting and blocking light generated by the light source to generate a grating image, and a projecting lens part making the grating image on a measurement target of the target substrate;

an image-capturing section capturing the grating image reflected by the measurement target of the target substrate; and

a control section controlling the work stage, the pattern-projecting section and the image-capturing section, calculating a reliability index of the grating image and phases of the grating image, which is corresponding to the measurement target, and inspecting the measurement target by using the reliability index and the phases.

2. The shape measurement apparatus of claim 1, wherein the shape measurement apparatus inspects a surface of a pad through the reliability index when the pad is the measurement target.

3. The shape measurement apparatus of claim 2, wherein the pad is to be electrically connected to an external device.

4. The shape measurement apparatus of claim 2, wherein the reliability index is at least one of an intensity, a visibility and a signal to noise ratio.

5. The shape measurement apparatus of claim 2, wherein the control section s determines the pad is bad, when the reliability index is out of a setup value.

6. The shape measurement apparatus of claim 5, further comprising a subsidiary light source for inspecting the measurement target of the target substrate, and wherein the control section determines that the pad is bad when light generated by the subsidiary light source is reflected by the pad and captured by the image-capturing section to form a two-dimensional image, and the pad is determined as bad in the two-dimensional image, even though the reliability index shows that the pad is good.

7. A shape measurement method, comprising:

acquiring a grating image reflected by a measurement target, while shifting the grating image for specific times;

acquiring a reliability index including at least one of an intensity, a visibility and a signal to noise ratio of the grating image by using the grating images; and

determining a pad for being electrically connected to an external device is good when the reliability index is within a setup value, and bad when the reliability index is out of the setup value, in case that the pad is the measurement target.

8. A method of measuring a three dimensional shape comprising:

illuminating grating pattern lights in a plurality of directions onto a measurement target while changing each of the grating pattern lights by N times and detecting the grating pattern lights reflected by the measurement target, to acquire N pattern images of the measurement target with respect to each direction;

extracting a phase {P_i(x,y)} and a brightness {A_i(x,y)} with respect to each direction corresponding to each position {i(x,y)} in an X-Y coordinate system from the pattern images;

extracting a height weight {W_i(x,y)} with respect to each direction by using a weight function employing the brightness as a parameter; and

calculating a weight height {W_i(x,y)·

H_i(x,y)} with respect to each direction by using a height based on the phase with respect to each direction and the height weight, and summing weight heights, to produce a height {Σ

W_i(x,y)·

H_i(x,y)/Σ

W_i(x,y)} at each position.

9. The method of claim 8, wherein the brightness corresponds to an average brightness that is obtained by averaging the detected grating pattern lights.

10. The method of claim 9, wherein the weight function further employs at least one of a visibility and an SNR (signal-to-noise ratio) with respect to each direction extracted from the pattern images with respect to each direction as parameters.

11. The method of claim 10, wherein the weight function further employs a measurement scope (λ

) corresponding to a grating pitch of each grating pattern light extracted from the pattern images with respect to each direction as a parameter.

12. The method of claim 11, wherein the measurement scope has at least two values according to the grating pattern lights.

13. The method of claim 10, wherein the weight function decreases the height weight, as the average brightness increases or decreases from a predetermined value.

14. The method of claim 13, wherein the predetermined value is a mid value of the average brightness.

15. The method of claim 10, wherein the weight function increases the height weight, as the visibility or the SNR increases.

16. The method of claim 10, wherein the weight function decreases the height weight, as the measurement scope increases.

17. The method of claim 10, wherein extracting the height weight with respect to each direction comprising dividing the pattern images into a shadow area, a saturation area and a non-saturation area, and

wherein the shadow area corresponds to an area, in which the average brightness is below a minimum brightness and the visibility or the SNR is below a minimum reference value,

the saturation area corresponds to an area, in which the average brightness is more than a maximum brightness and the visibility or the SNR is below the minimum reference value, and

the non-saturation area corresponds to a remaining area except the shadow area and the saturation area.

18. The method of claim 17, wherein the weight function is regarded as ‘

0’

to obtain the height weight in the shadow area and the saturation area.

19. The method of claim 18, wherein the weight function corresponding to the non-saturation area decreases the height weight, as the average brightness increases or decreases from a mid value of the average brightness, increases the height weight as the visibility or the SNR increases, and decreases the height weight as the measurement scope increases.

20. The method of claim 8, wherein sum of the height weights is equal to 1 {Σ

W_i(x,y)=1}.

21. A method of measuring a three dimensional shape comprising:

illuminating grating pattern lights in a plurality of directions onto a measurement target while changing each of the grating pattern lights by N times and detecting the grating pattern lights reflected by the measurement target, to acquire N pattern images of the measurement target with respect to each direction;

extracting a phase {P_i(x,y)} and a visibility {V_i(x,y)} with respect to each direction corresponding to each position {i(x,y)} in an X-Y coordinate system from the pattern images;

extracting a height weight {W_i(x,y)} with respect to each direction by using a weight function employing the visibility as a parameter; and

calculating a weight height {W_i(x,y)·

H_i(x,y)} with respect to each direction by multiplying a height based on the phase by the height weight, and summing weight heights, to produce a height {Σ

W_i(x,y)·

H_i(x,y)/Σ

W_i(x,y)} at each position.