JP2013055266A - Straight line detection method and positioning method of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a straight line detection method which allows for highly accurate detection of a straight line, e.g., a scribe line, and to provide a positioning method of a substrate.SOLUTION: The straight line detection method includes a step for detecting the position of an edge of a scribe line in the X direction, a step for dividing a detection area into a plurality of selection areas arranged in the Y direction while overlapping the edges each other in the Y direction, a step for detecting the centroid position of the edge in the X direction by performing projection summation of the X direction positions of the edges in the Y direction for each selection area, a labeling step for labeling each centroid position, a step for determining a straight line equation of each edge passing through the coordinate position of each edge, determined by the centroid position of each edge thus labeled in the X direction and the centroid position of each selection area in the Y direction, by applying the least-squares method thereto, a step for detecting the inclination of the scribe line based on the equation, and a step for positioning the substrate.

Description

  The present invention relates to a straight line detection method and a substrate positioning method.

  When pattern printing is performed on a semiconductor wafer as a substrate, it is necessary to adjust the angular position of the semiconductor wafer so that the scribe line faces a certain direction. Here, the scribe line is a line drawn at the chip boundary in order to execute dicing for dividing the semiconductor wafer into chips.

  In Patent Document 1, an image of a semiconductor wafer on a stage is taken by a camera, an angle deviation of a scribe line with respect to a reference line is obtained from the image, and the angle deviation of the wafer is corrected by rotating the stage by the obtained angle deviation. A wafer alignment method is disclosed.

JP 10-64981 A

  When the scribe line is used for positioning the substrate as described above, generally, the scribe line is detected by detecting the edge of the scribe line and specifying the position of the continuous edge. However, when a scribe line is photographed by a camera, there is generally a problem that an edge is unclear and its identification is difficult. For this reason, there exists a problem that a scribe line cannot be detected correctly.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a straight line detection method and a substrate positioning method capable of detecting a straight line such as a scribe line with high accuracy.

  According to a first aspect of the present invention, in a straight line detection method for extracting a straight line from a two-dimensional image including a straight line and detecting its position and inclination, an edge extracting step for extracting the edge of the straight line, and detecting the straight line A center-of-gravity detection step of detecting a center-of-gravity position in the X direction of the edge in each selected region after performing both of the region dividing step of dividing the power detection area into a plurality of selected regions in the Y direction; A labeling step for labeling the center of gravity in the X direction of each edge in each selected area detected in the center of gravity detection step based on the position in the X direction, and the center of gravity in the X direction of each edge labeled in the labeling step And applying the least squares method to the centroid coordinate position of each edge determined by the centroid position of each selected region in the Y direction, Characterized by comprising a equations specifying step of determining the equation of a straight line passing through the center of gravity coordinates of these.

  According to a second aspect of the present invention, in the first aspect of the present invention, in the region dividing step, the detection area is set to Y so that edges in the Y direction of a plurality of selected regions overlap each other. Divide into multiple selection areas in the direction.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a detection area including a plurality of straight lines is set as the detection area, and in the labeling step, detection is performed in the center of gravity detection step. The center-of-gravity positions are labeled for each center-of-gravity position corresponding to each straight line based on the position in the X direction.

  According to a fourth aspect of the present invention, in the substrate positioning method for positioning the substrate on which the straight portion is formed, an edge extraction step for extracting an edge of the straight portion, and a detection area where the straight portion is to be detected are set in the Y direction. After performing both of the region dividing step of dividing the selected region into a plurality of selected regions, the X-direction edge of the straight line portion detected in the edge extracting step for each selected region divided in the region dividing step The center of gravity position detection step for detecting the center of gravity position in the X direction of the edge of the straight line portion in these selected regions by projecting and adding the position of Y in the Y direction, and each of the selection regions detected in the center of gravity detection step In the labeling step, the labeling step of labeling the center-of-gravity position of the edge in the X direction for each center-of-gravity position corresponding to each linear portion based on the position in the X direction By applying a least-squares method to the center-of-gravity coordinate position of each edge determined by the center-of-gravity position in the X direction of the edge of the labeled linear part and the center of gravity in the Y direction of each selected region, An equation specifying step for obtaining an equation of the straight line portion passing through the barycentric coordinate position, an inclination detecting step for detecting the inclination of the straight line portion based on the equation specified in the equation specifying step, and an inclination detecting step And a positioning step of positioning the substrate by rotating the substrate in a plane parallel to the principal surface based on the tilt.

  According to the first aspect of the present invention, it is possible to detect a straight line with high accuracy even when the straight edge is unclear, when a plurality of straight edges are included, or when there are scratches or dust.

  According to the invention described in claim 2, since the number of the plurality of selection areas can be increased, the edge detection accuracy can be improved, and the size of the plurality of selection areas in the Y direction is increased. This makes it possible to detect an unclear edge.

  According to the third aspect of the present invention, it becomes possible to detect a plurality of straight lines at once, and to eliminate the influence of scratches and dust.

  According to the fourth aspect of the present invention, even when the edge of the straight line portion is unclear, the straight line portion can be detected with high accuracy. In addition, since the number of the plurality of selection areas can be increased, the detection accuracy of the straight line portion can be improved, and the size of the plurality of selection areas in the Y direction can be increased, so that an unclear edge However, the labeling can reduce the influence of scratches and dust and detect a plurality of straight lines. For this reason, it becomes possible to position a board | substrate accurately.

1 is a perspective view schematically showing an exposure apparatus 100 to which the present invention is applied. 3 is a schematic diagram schematically showing a moving mechanism of a substrate 2 together with a camera 15. FIG. It is a flowchart which shows a straight line detection and the positioning operation of a board | substrate. It is explanatory drawing which shows typically the relationship of the detection area A and three straight lines L1, L2, and L3 showing a scribe line. It is explanatory drawing which shows the state which divides | segments the detection area A typically. It is explanatory drawing which shows the gravity center position of an edge typically.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the configuration of an exposure apparatus to which the present invention is applied will be described. FIG. 1 is a perspective view schematically showing an exposure apparatus 100 to which the present invention is applied.

  The exposure apparatus 100 is for exposing a pattern of a mask 3 onto a substrate 2 such as a semiconductor wafer, and includes a light source 4 such as an ultrahigh pressure mercury lamp, a condenser mirror 5, a dichroic mirror 6, and a fly. An eye lens (compound lens) 7 and a collimator mirror 1 are provided.

  In this exposure apparatus 100, the light emitted from the light source 4 is collected by the condenser mirror 5 and enters the dichroic mirror 6. In the dichroic mirror 6, only light having a wavelength necessary for exposure is reflected toward the fly-eye lens 7 out of the light incident thereon. The light that has passed through the fly-eye lens 7 is collimated by the collimator mirror 1 to become parallel light, and is irradiated onto the substrate 2 through the mask 3. At this time, the mask 3 and the substrate 2 are arranged in a region where the light that has passed through the fly-eye lens 7 overlaps with each other, and pattern exposure can be performed with a uniform illuminance distribution.

  FIG. 2 is a schematic diagram schematically showing the moving mechanism of the substrate 2 together with the camera 15.

  The substrate 2 is supported by a support member 13. The support member 13 can be moved in the X, Y, and θ directions by the moving mechanism 14. Then, the image of the substrate 2 supported by the support member 13 is captured by the camera 15 and subjected to image processing as will be described later.

  Next, a straight line detection method and a substrate positioning method according to the present invention will be described. FIG. 3 is a flowchart showing the straight line detection and the substrate positioning operation for positioning the substrate by detecting a scribe line as a straight line portion formed on the substrate by the straight line detection method according to the present invention. FIG. 4 is an explanatory diagram schematically showing the relationship between the detection area A and three straight lines L1, L2, and L3 representing scribe lines. Further, FIG. 5 is an explanatory diagram schematically showing a state in which the detection area A is divided.

  When detecting a straight line composed of scribe lines, first, the substrate 2 is photographed (step S1). At this time, the image data of the surface of the substrate 2 is acquired by photographing the substrate 2 supported by the support member 13 with the camera 15.

  Next, a detection area A in the X and Y directions on the surface of the substrate 2 that should detect a straight line representing a scribe line in the image data on the surface of the substrate 2 is set (step S2). In this case, as shown in FIG. 4, a rectangular detection area A in the X and Y directions from the coordinates (Sx, Sy) to the coordinates (Ex, Ey) is set. Here, the X direction and the Y direction indicate two directions orthogonal to each other set with respect to the main surface of the substrate 2. This direction is a direction appropriately set for the exposure apparatus or the like.

  Next, by performing edge extraction on the image in the detection area A, the positions of the edges in the X direction of the straight lines L1, L2, and L3 representing the scribe lines in each region are extracted (step S3). In this case, the positions of the edges of the straight lines L1, L2, and L3 with respect to the Y direction are detected by differentiating the detection area A in the X direction. Here, differentiation is a technique for extracting an edge portion in image processing, and is to take a luminance difference between pixels adjacent to each other or pixels separated by a certain interval with respect to a specific image. For example, the differentiation in the X direction with respect to the straight lines L1, L2, and L3 shown in FIG. 4 means that the difference in luminance between pixels adjacent in the X direction or between pixels separated by a fixed interval at each position in the Y direction. Is to take.

  Next, an area dividing step for dividing the detection area A into a plurality of areas arranged in the Y direction with the edges in the Y direction overlapping each other is executed (step S4). At this time, first, as shown in FIG. 4, the detection area A is divided into n parts in the Y direction. Here, n is an integer of 2 or more. Then, as shown in FIGS. 4 and 5, m areas adjacent to each other from the n divided areas are selected by shifting the n divided areas one by one. Here, m is an integer smaller than n. As a result, as shown in FIG. 5, the end portions in the Y direction from K = 1 to K = nm + 1, which are composed of m areas adjacent to each other, are arranged in the Y direction, which overlap each other [n− m + 1] selection areas are set. Note that FIG. 5 illustrates a case where n = 8, m = 3, and n−m + 1 = 6.

  Then, for each [n−m + 1] selected regions, the X direction positions of the edges detected in the edge extraction step (step S3) are projected and added in the Y direction, so that the X directions of the edges in these m regions are obtained. Is detected (step S5). Here, projecting and adding the position of the edge in the X direction in the Y direction means adding the differential values in the X direction shown in FIGS. 4 and 5 along the Y direction.

  FIG. 6 is an explanatory diagram schematically showing the center of gravity position of the edge.

  In FIG. 6, the barycentric position of the left edge of the straight line L1 representing the scribe line in each of [n−m + 1] selected areas is P1, and the straight line representing the scribe line in each of [n−m + 1] selected areas. The center of gravity of the right edge in L1 is M1, the center of gravity of the left edge in the straight line L2 representing the scribe line in each of [n−m + 1] selected areas is P2, and each of [n−m + 1] selected areas. The center of gravity of the right edge of the straight line L2 representing the scribe line at M2 is M2, and the center of gravity of the left edge of the straight line L3 representing the scribe line in each of the [n−m + 1] selected regions is P3, [n−m + 1]. The center of gravity of the right edge of the straight line L3 representing the scribe line in each of the selected areas is indicated by M3 To have. In this figure, Th indicates a threshold when detecting the center of gravity of the edge. Here, the directions of P1, P2, and P3 and M1, M2, and M3 are different from each other based on the sign of the difference result at the time of differentiation described above.

  Next, as indicated by broken lines in FIG. 6, the center-of-gravity positions P1, P2, P3, M1, M2, and M3 detected in the center-of-gravity position detection step (step S5) are converted into straight lines L1, Labeling is performed for each barycentric position corresponding to L2 and L3 (step S6). That is, those having a difference in position in the X direction equal to or less than a certain value are grouped for each barycentric position P1, P2, P3, M1, M2, and M3 in the X direction.

  When labeling is executed, data whose number of data in each group is smaller than a preset value is excluded from the data as not being a straight line. Further, when the widths of the straight lines L1, L2, and L3 representing the scribe line are constant and known, the widths of the straight lines L1, L2, and L3 are determined from the coordinate difference between P1 and M1, P2 and M2, and P3 and M3. By calculating and comparing with the width of a known scribe line, a straight line that is not a scribe line can be excluded from the data, and detection accuracy can be improved.

  Then, an equation of an edge straight line passing through the barycentric coordinate positions determined by the barycentric positions P1, P2, P3, M1, M2, and M3 is obtained (step S7). At this time, the X coordinate positions of P1, P2, P3, M1, M2, and M3 are used as the X coordinates of the gravity center positions P1, P2, P3, M1, M2, and M3. In addition, as the Y coordinates of the center-of-gravity positions P1, P2, P3, M1, M2, and M3, those obtained by the following formula are used.

y = Sy + (m + 2k−2) (Ey−Sy) / 2n
However, k = 1, 2, 3,... [Nm + 1].

  Then, an equation of each edge straight line passing through these barycentric coordinate positions is obtained by applying the least square method to the coordinate values of the barycentric coordinate positions thus obtained. The obtained equation is expressed by the following equation for each edge straight line.

y = ax + b
Here, when the number of each selected region in the Y direction is small, the accuracy in obtaining the equation of each edge straight line is lowered. On the other hand, when the number of each selection area is increased, the accuracy when obtaining each edge straight line is improved, but the size in the Y direction of each selection area is reduced accordingly, so that the edge is reduced. If it is unclear, it is easily affected by scratches and dust. Therefore, in the present invention, the detection area A is divided into n and then m areas are selected, and the selection areas are set so that the edges in the Y direction overlap each other. Detection is possible even in a clear case, and it is possible to reduce the influence of scratches and dust while improving the accuracy when obtaining each edge straight line.

  Next, the inclination of the edge straight line representing the scribe line is detected based on the obtained equation (step S8). At this time, a plurality of edge straight lines representing the edges of the scribe line are detected and they are parallel to each other. Therefore, the average value of those detected by each equation is used as the inclination.

  Then, based on the obtained inclination of the edge straight line representing the edge of the scribe line, the substrate 2 is rotated in a plane parallel to the main surface by using the moving mechanism 14 shown in FIG. Is positioned (step S9).

  In the above-described embodiment, an area dividing step of dividing the detection area in the X and Y directions in which the straight line should be detected into a plurality of selection areas in the Y direction after executing the edge extracting step of extracting straight edges. However, the edge extraction step may be executed after the region dividing step.

  Further, in the above-described embodiment, the scribe line as the linear portion formed on the substrate is detected, but other linear portions may be detected. In this case, the straight line portion may be not only a portion that continues in the Y direction described above but also a portion that is partially cut.

DESCRIPTION OF SYMBOLS 1 Collimating mirror 2 Board | substrate 3 Mask 4 Light source 5 Condensing mirror 6 Dichroic mirror 7 Fly eye lens 13 Support member 14 Moving mechanism 15 Camera 100 Exposure apparatus A Detection area L1 Straight line L2 Straight line L3 Straight line

Claims (4)

In a straight line detection method for extracting a straight line from a two-dimensional image including a straight line and detecting its position and inclination,
After performing both the edge extraction step of extracting the edge of the straight line and the region dividing step of dividing the detection area where the straight line should be detected into a plurality of selection regions in the Y direction, A centroid detection step of detecting the centroid position of the edge in the X direction;
A labeling step of labeling the center of gravity in the X direction of each edge in each selection area detected in the center of gravity detection step based on the position in the X direction;
A least square method is applied to the gravity center coordinate position of each edge determined by the gravity center position in the X direction of each edge labeled in the labeling step and the gravity center position in the Y direction of each selection region. An equation specifying step for obtaining an equation of a straight line passing through these barycentric coordinate positions,
A straight line detection method comprising: The straight line detection method according to claim 1,
In the area dividing step, the detection area is divided into a plurality of selection areas in the Y direction so that edges in the Y direction of the plurality of selection areas overlap each other. The straight line detection method according to claim 1 or 2,
While setting a detection area including a plurality of straight lines as the detection area,
In the labeling step, a straight line detection method of labeling each gravity center position detected in the gravity center detection step for each gravity center position corresponding to each straight line based on a position in the X direction. In the substrate positioning method for positioning the substrate on which the linear portion is formed,
After performing both the edge extracting step of extracting the edge of the straight line portion and the region dividing step of dividing the detection area where the straight line portion is to be detected into a plurality of selection regions in the Y direction, the region dividing step is performed. For each selected area divided in the process, the position of the edge in the X direction of the straight line portion detected in the edge extraction process is projected and added in the Y direction, so that the X direction of the edge of the straight line part in these selected areas A center-of-gravity position detection step for detecting the center-of-gravity position
A labeling step of labeling the center of gravity in the X direction of each edge in each selection area detected in the center of gravity detection step for each center of gravity corresponding to each straight line portion based on the position in the X direction;
The least square method is applied to the center-of-gravity coordinate position of each edge determined by the center-of-gravity position in the X direction of the edge of the straight line portion labeled in the labeling step and the center-of-gravity position in the Y direction of each selected region. An equation specifying step for obtaining an equation of the straight line portion passing through these barycentric coordinate positions,
An inclination detecting step of detecting the inclination of the straight line portion based on the equation specified in the equation specifying step;
A positioning step of positioning the substrate by rotating the substrate in a plane parallel to its principal surface based on the tilt detected in the tilt detection step;
A method for positioning a substrate, comprising:

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