Apparatus and method for measuring shape

Abstract

A shape measuring apparatus and a shape measuring method suited for measuring an edge profile of a thin sample such as a semiconductor wafer or the like is provided. A distribution of surface angle and an edge profile of a measurement site is calculated by emitting light at sequentially different angle to the measurement site of a wafer by sequentially switching and lighting a plurality of LEDs each disposed at one of plurality of positions in one plane by an LED driving circuit, obtaining an image data showing a luminance distribution of the reflected light form the measurement site through a camera by a calculator each time light is emitted and, estimating an emitting angle of the light when the luminance of the reflected light becomes peak based on image data and emitting angle of the light corresponding to each LED by the calculator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are each a configuration diagram schematically showing a shape measuring apparatus Z according to an embodiment of the present invention;

FIG. 2A is a diagram illustrating a definition of light emitting angle;

FIG. 2B is a diagram illustrating a definition of surface angle;

FIG. 3 is a diagram illustrating a property of a telecentric lens system camera which may be employed in the shape measuring apparatus Z;

FIG. 4 is a diagram schematically showing a relationship between a surface angle and a light path at the measurement site when the telecentric lens system camera is employed for the shape measuring apparatus Z;

FIG. 5 is a graph illustrating a surface angle distribution and an edge profile of the measurement site calculated by the shape measuring apparatus Z;

FIG. 6 is a diagram illustrating a property of a non-telecentric lens system camera which may be employed in the shape measuring apparatus Z;

FIG. 7 is a diagram schematically showing a relationship between a surface angle and a light path at the measurement site when a non-telecentric lens system camera is employed for the shape measuring apparatus Z;

FIG. 8A is a diagram schematically illustrating a first example of a shape at the measurement site;

FIG. 8B is a diagram schematically illustrating a first example of an image photographed by a camera of the shape measuring apparatus Z;

FIG. 9A is a diagram schematically illustrating a second example of a shape at the measurement site;

FIG. 9B is a diagram schematically illustrating a second example of an image photographed by the camera of the shape measuring apparatus Z;

FIG. 10 is a diagram illustrating an example of an image photographed by the shape measuring apparatus Z;

FIG. 11 is a graph illustrating an example of a relationship between light emitting angle and reflected light luminance at a predetermined calculating object position;

FIG. 12 is a flow chart illustrating measuring procedures performed by the shape measuring apparatus Z;

FIG. 13 is a configuration diagram schematically showing a shape measuring apparatus Z′ which is a first application example of the shape measuring apparatus Z;

FIG. 14A is a diagram illustrating states before fitting processing of surface angles and edge profiles corresponding to each of two cameras obtained by the shape measuring apparatus Z′;

FIG. 14B is a diagram illustrating states after fitting processing of surface angle and edge profile corresponding to each of two cameras obtained by the shape measuring apparatus Z′;

FIGS. 15A and 15B are each a configuration diagram schematically showing a shape measuring apparatus Z2 which is a second application example of the shape measuring apparatus Z;

FIGS. 16A and 16B are each a configuration diagram schematically showing a shape measuring apparatus Z3 which is a third application example of shape measuring apparatus Z;

FIG. 17A is a diagram schematically showing an example of a measurement site P(a) to which sheet light is being emitted;

FIG. 17B is a diagram schematically showing an example of a measurement site P(b) to which sheet light is being emitted;

FIG. 17C is a diagram schematically showing an example of an image (c) of the measurement site P photographed by the camera; and

FIG. 18 is a flow chart illustrating measuring control procedures performed by the shape measuring apparatus Z3.

Claims

1. A shape measuring apparatus for measuring a shape of an edge of a thin sample comprising: first light emitting means for emitting light at sequentially different emitting angles with respect to a measurement site which is an edge surface of the thin sample by lighting a light source at each of a plurality of positions in one plane;first light detecting means for detecting a one-dimensional or two-dimensional luminance distribution of light emitted by the first light emitting means and reflected at the measurement site in approximately specular direction at a predetermined position;reflected light luminance obtaining means for obtaining a luminance distribution of the reflected light from the measurement site through the first light detecting means each time light is emitted at sequentially different emitting angles by the first light emitting means; andsurface angle distribution calculating means for calculating a distribution of a surface angle of the measurement site based on the luminance distribution of the reflected light obtained by the reflected light luminance obtaining means and the emitting angle of the light emitted by the first light emitting means.

2. The shape measuring apparatus according to claim 1 wherein, the surface angle distribution calculating means calculates the surface angle of each of calculating object positions by performing calculation for estimating the emitting angle of the light when a luminance of the reflected light is peak based on corresponding relationship between the emitting angle of the light and the luminance of the reflected light as for each of the plurality of calculation object positions in a light detecting range of the first light detecting means.

3. The shape measuring apparatus according to claim 1 wherein, the first light emitting means is move type light emitting means which emits light at sequentially different angles to the measurement site by sequentially moving a predetermined light source to each of a plurality of positions in the one plane and lighting the light source.

4. The shape measuring apparatus according to claim 1 wherein, the first light emitting means is switch type light emitting means which emits light at sequentially different angles to the measurement site by sequentially switching and lighting a plurality of light sources each disposed at one of a plurality of positions in the one plane.

5. The shape measuring apparatus according to claim 4 wherein, the plurality of light sources in the switch type light emitting means are disposed on a circular arc of which a disposed position of the measurement site is the center.

6. The shape measuring apparatus according to claim 1, including a plurality of the first light detecting means each disposed in a different direction with respect to the measurement site, and wherein the surface angle distribution calculating means calculates a distribution of the surface angle of a part region of the measurement site based on the luminance distribution of the reflected light and the emitting angle of the light for each luminance distribution of the reflected light obtained through each of the plurality of the first light detecting means, andfurther including combining calculation means for calculating a distribution of the surface angles or a surface shape of the whole measurement site by combining each calculated result of the distribution of the surface angle of the part region calculated by the surface angle distribution calculating means or each surface shape of the measurement site based on the calculated result.

7. The shape measuring apparatus according to claim 6 wherein, two of the first light detecting means are disposed in directions making approximately 90° with respect to the measurement site.

8. The shape measuring apparatus according to claim 6 wherein, in the process where the switch type light emitting means sequentially switching and lighting the plurality of light sources, a plurality of light sources corresponding to each of the plurality of the first light detecting means are simultaneously lighted.

9. The shape measuring apparatus according to claim 1, including second light emitting means for emitting sheet light with respect to the measurement site,second light detecting means for detecting a two-dimensional luminance distribution of the light emitted by the second light emitting means and reflected at the measurement site in a direction except the specular direction, andlight cutting method shape calculating means for calculating a surface shape of the measuring site by calculation of a light cutting method on the basis of a result detected by the second light detecting means.

10. The shape measuring apparatus according to claim 9 wherein, the first light detecting means which detects a two-dimensional luminance distribution doubles as the second light detecting means.

11. The shape measuring apparatus according to claim 9 wherein, the second light emitting means emit sheet light in a plane including a cross section of the thickness direction of the thin sample in the measurement site, and a lighting position of the light source of the first light emitting means is positioned at one side and a disposed position of the first light detecting means is positioned at another side among both sides of the plane including the sheet light.

12. The shape measuring apparatus according to claim 9, including first adoption discrimination means which discriminates that which one of a calculated result of the distribution of the surface angle of the measurement site calculated by the surface angle distribution calculating means or a calculated result of the surface shape of the measurement site calculated by the light cutting method shape calculating means is adopted for shape evaluation of the measurement site based on a luminance detected by the first light detecting means while light is being emitted by the first light emitting means.

13. The shape measuring apparatus according to claim 12 wherein, the first adoption discrimination means discriminates that which one of the calculated results is adapted according to whether a predetermined number of strip-shaped image is included or not in the image based on the luminance detected by the first light detecting means while the one or the plurality of light sources of the first light emitting means is being lighted.

14. The shape measuring apparatus according to claim 9 including second adoption discrimination means which discriminates that which one of a calculated result of the distribution of the surface angle of the measurement site calculated by the surface angle distribution calculating means or a calculated result of the surface shape of the measurement site calculated by the light cutting method shape calculating means is adopted for shape evaluation of the measurement site based on a luminance detected by the second light detecting means while light is being emitted by the second light emitting means.

15. The shape measuring apparatus according to claim 14 wherein, the second adoption discrimination means discriminates that which one of the calculated results is adapted according to whether a continuing linear image is included or not in a predetermined range in the image based on the luminance detected by the second light detecting means while sheet light is being emitted by the second light emitting means.

16. A shape measuring method for measuring a shape of an edge of a thin sample comprising: a first light emitting process for emitting light at sequentially different emitting angles with respect to a measuring site which is an edge surface of a thin sample;a first light detecting process for detecting a one-dimensional or two-dimensional luminance distribution of reflected light emitted in the first light emitting process and reflected at the measurement site in approximately specular direction by light detecting means at a predetermined position;a reflected light luminance obtaining process for obtaining a luminance distribution of the reflected light from the measurement site by performing the first light detecting process each time light is emitted at sequentially different emitting angles by the first light emitting process; anda surface angle distribution calculating process for calculating a distribution of a surface angle of the measurement site based on the luminance distribution of the reflected light obtained by the reflected light luminance obtaining process and the emitting angle of the light emitted in the first light emitting process.

17. The shape measuring method according to claim 16, comprising a second light emitting process for emitting sheet light to the measurement site by predetermined light emitting means, a second light detecting process for detecting a two-dimensional luminance distribution of the light emitted in the second light emitting process and reflected at the measurement site in a direction except the specular direction by light detecting means, anda light cutting method shape calculating process for calculating a surface shape of the measurement site by calculation of a light cutting method based on a result detected in the second light detecting process.

18. The shape measuring method according to claim 17, comprising a first adoption discrimination process which discriminates that which one of a calculated result of the distribution of the surface angle of the measurement site calculated in the surface angle distribution calculating process or a calculated result of the surface shape of the measurement site calculated in the light cutting method shape calculating process is adopted for shape evaluation of the measurement site based on a luminance detected in the first light detecting process while light is being emitted in the first light emitting process.

19. The shape measuring method according to claim 17, comprising a second adoption discrimination process which discriminates that which one of a calculated result of the distribution of the surface angle of the measurement site calculated in the surface angle distribution calculating process or a calculated result of the surface shape of the measurement site calculated in the light cutting method shape calculating process is adopted for shape evaluation of the measurement site based on a luminance detected in the second light detecting process while light is being emitted in the second light emitting process.