JP2007232464A - Dimension measuring method and dimension measuring apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a measurement specification point for measuring a dimension to be specified correctly, even when a multi-layer pattern formed on an object to be measured is displaced between layers from a design pattern, in order to improve reliability for measuring dimensions of a pattern formed on a substrate. <P>SOLUTION: A dimension measuring method is provided, which is applied to the object to be measured with the pattern having at least two layers, and comprises: a first step of comparing design patterns D11, D12 and D21 of respective layers with photographed patterns G11, G12 and G21 of respective layers of the object to be measured; and a second step of calculating relative displacement values of the photographed patterns G12 and G21 of respective layers of the object to be measured from the design patterns D12 and D21 of respective layers in design, based on comparison results of the first step. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a measurement target such as a semiconductor integrated circuit finely processed to the submicron order and an etching product accompanying the same is picked up by an image pickup device, the picked-up image is processed, and the measurement target is layered at two or more times. And a dimension measuring apparatus for executing the method.

  When a pattern with a fine line width is generated by partially forming layers at different timings by an etching process, which is a semiconductor manufacturing process, on the substrate, since the pattern is fine, the width and spacing of each pattern Therefore, it is necessary to generate the shape dimension and the like with high accuracy without shifting the position.

  The patterns generated at such different timings are displaced due to differences in apparatuses that form the patterns, alignment errors, and the like. In the pattern formation process, the pattern may be formed to be thick or thin. Therefore, in such pattern formation, a pattern is captured by an imaging camera, image recognition is performed on a computer screen, and the pattern dimension is measured to grasp the pattern formation state.

  Such patterns are formed across multiple layers as a result of advances in microfabrication techniques such as etching. A conventional pattern dimension measuring method in the case where patterns are formed in such a multilayer will be described (for example, see Patent Document 1).

  First, an instruction substrate (first substrate) on which patterns are formed in multiple layers is imaged. A feature portion of a pattern on the substrate is designated on the captured image. This designated location is registered in the template image. The designated measurement point in the template image is designated on the coordinates and stored. Next, the substrate to be measured (another substrate) is imaged. An image having a shape that matches the template image (matched image) is searched from the captured images of the other substrates. The designated measurement point on the searched coincidence image is designated according to the stored stored data of the designated measurement point. Then, the dimension of the pattern is measured according to the designated measurement designated point.

However, in this dimension measurement method, the measurement designated points of a plurality of patterns extending over a plurality of layers on another substrate are displaced relative to the measurement designated points of a plurality of patterns extending over a plurality of layers on the first substrate. Originally, there is a case where the dimension between the patterns between the layers to be measured, not between the patterns between the layers to be measured, may be measured, and it is difficult to ensure the reliability for the measurement of the pattern dimensions.
Japanese Patent No. 3059602

  Therefore, the problem to be solved by the present invention is that the measurement designation point for dimension measurement can be correctly designated on the substrate even if the pattern formed in multiple layers on the measurement object is displaced from the design pattern between the layers, It is to increase the reliability of the measurement of the dimension of the pattern formed on the substrate.

  The dimension measuring method according to the present invention includes a first step for comparing the design pattern of each layer and each layer of the imaging pattern of the measurement object, and design of each layer in each layer of the imaging pattern of the measurement object from the comparison result of the first step. And a second step of calculating a relative deviation amount from the pattern.

  The pattern is preferably a pattern with a fine line width on the order of submicron formed by forming layers on the substrate at different timings by an etching process, which is a semiconductor manufacturing process, but is not limited thereto. The design pattern is not limited to the design method. Further, the imaging format of the imaging pattern is not limited. The object to be measured is preferably a substrate, but is not limited to the substrate, and may be anything that can form a pattern.

  According to the present invention, the measurement position is shifted due to the difference in the pattern of each object to be measured, etc., or because the pattern is thicker or thinner than the prescribed dimension. In the first step, the design pattern of each layer is compared with the imaging pattern of each layer of the measurement object, and in the second step, the design pattern of each layer of the imaging pattern of each layer of the measurement object is determined based on the result of the comparison. Since the relative deviation amount from the design pattern is calculated, the measurement position can be correctly specified, and thereby the pattern dimension can be accurately measured with high reliability.

  In the present invention, the first step of comparing the design pattern of each layer and the imaging pattern of each layer of the measurement object, and the design pattern of each layer on the design in the imaging pattern of each layer of the measurement object from the comparison result of the first step Since the dimension of the measurement object is measured by the second step of calculating the relative deviation amount from the measurement object, the dimension of the measurement object can be accurately measured with high reliability.

  Hereinafter, a dimension measuring method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a schematic configuration of a dimension measuring apparatus used for carrying out the dimension measuring method of the embodiment. FIG. 1 shows the X-axis direction, the Y-axis direction, and the Z-axis direction. These axes are orthogonal to each other. With reference to these drawings, the dimension measuring device 2 includes an imaging device 4 for imaging a measurement object and a control device 6 with a computer that controls the imaging device 4. The imaging device 4 and the control device 6 are connected so as to be able to transmit information to each other.

  The imaging device 4 includes an imaging base 8 having a rectangular shape in plan view that is long in the X-axis direction and constant in the Y-axis direction. A pair of guide rails 10 extending in parallel with each other in the X-axis direction are provided on the imaging base 8. A rectangular flat plate-shaped moving table 12 is movable in the X-axis direction on the pair of guide rails 10. An encoder (not shown) is integrally installed on the moving table 12. The linear scale 14 provided along the guide rail 10 and the encoder constitute a linear encoder that measures the amount of movement of the moving table 12 in the X-axis direction.

  On the imaging base 8, a gate-type imaging base 16 is installed so as to straddle the movable table 12 in the Y-axis direction. The imaging platform 16 is provided with an area type imaging device (imaging means) 18 as a camera mechanism and a high-speed autofocus mechanism 20 movably in the Y-axis direction in addition to a camera movement mechanism (not shown). The camera moving mechanism moves the area-type imaging device 18 and the high-speed autofocus mechanism 20 integrally to the X coordinate commanded from the control device 6. The area-type imaging device 18 has an objective lens like a microscope and includes a two-dimensional CCD imaging device. The imaging magnification can be changed by exchanging the objective lens.

  The substrate 22 is, for example, a glass substrate for a liquid crystal panel, and is positioned on the moving table 12 by a plurality of positioning pins 23 and a plurality of pushers 26.

  1 moves the area-type imaging device 18 in the X-axis direction and the Y-axis direction relative to the substrate 22 by moving the moving table 12 and the imaging stand 16 of the imaging device 4. An image of a predetermined portion above is taken, the image is taken into the control device 6, the dimension measurement position of the element formed on the substrate is designated by image processing in the control device 6, and the dimension at the designated measurement position is measured. Be able to.

  The control device 6 includes a computer main body (which constitutes control means, arithmetic means, data generation means, etc.), a keyboard, a display, and a hard disk device (which constitutes storage means). Command can be sent, an image captured by the area type imaging device 18 of the imaging device 4 can be observed, and a program for controlling the imaging device 4 can be input. The computer program for dimension measurement for controlling the imaging device 4 may be installed in the computer of the control device 6 from the beginning, or may be downloaded from the outside via a network.

  The computer of the control device 6 is equipped with a computer program for executing the dimension measuring method described below.

  Hereinafter, the dimension measuring method according to the embodiment will be described with reference to FIG. In the following example, the object to be measured is a substrate 22 on which a pattern is formed at two timings, and a distance between edges of two patterns is measured with respect to the substrate 22.

  FIG. 2A is an example of image representation of the first layer design pattern data. The design pattern data is stored in the storage means of the control device 6. FIG. 2A shows a design screen D1 having a rectangular shape in accordance with a captured image of the substrate 22 by the area type imaging device 18 (imaging means), and two in the first layer displayed in the design screen D1. Design patterns D11 and D12 are shown.

  FIG. 2B is an example of image representation of the design pattern data of the second layer. This design pattern data is stored in the storage means in the computer of the control device 6. FIG. 2B shows a design screen D2 having a shape that matches the captured image of the substrate 22 by the area-type imaging device 18, and one design pattern D21 in the second layer displayed in the design screen D2. It is shown.

  Both the first and second layer design screens D1 and D2 have screen configurations of first and second orthogonal XY two-dimensional coordinates in which the upper left corner which is the intersection of the upper side and the left side is the coordinate origin O1 and O2. ing.

  FIG. 3 shows a composite design screen D3 in which the first layer design screen D1 and the second layer design screen D2 are superimposed. The composite design screen D3 also has a screen configuration of third orthogonal XY two-dimensional coordinates with the upper left corner, which is the intersection of the upper side and the left side, as the coordinate origin O3. In the third orthogonal XY two-dimensional coordinates, the coordinate origin O3 coincides with the coordinate origins O1 and O2. In FIG. 3, the coordinates (X, Y) of the edge E1 below the Y-axis direction of the first layer design pattern D12 are (250, 350), and the coordinates of the edge E2 above the Y-axis direction of the second layer design pattern D21. (X, Y) is (250, 450). That is, both edges E1, E2 are at the same position in the X-axis direction, and the coordinate positions in the Y-axis direction are separated by “100” in the vertical and vertical coordinate distances. These two edges E1 and E2 serve as measurement designated points for measuring dimensions, and the distance between both edges E1 and E2 in the Y-axis direction is a dimension to be measured.

  In the distance between the edges E1 and E2, the coordinate position of the edge E1 of the first layer design pattern D12 and the coordinate position of the edge E2 of the second layer design pattern D21 are relatively determined by design.

  The design pattern data of each layer described above is stored in the storage means in the computer built in the control device 6.

  FIG. 4 shows an imaging screen G of a substrate having two patterns on the first layer and one pattern on the second layer. In the pattern shown on the imaging screen G, G11 and G12 are first layer imaging patterns, and G21 is a second layer imaging pattern. Also in FIG. 4, orthogonal XY two-dimensional coordinates are formed with the upper left corner, which is the intersection of the upper side and the left side, as the coordinate origin O4.

  The measurement position of the first layer imaging pattern G12 is the edge E3, and the measurement position of the second layer imaging pattern G21 is the edge E4.

  In the imaging screen G, the first layer imaging patterns G11 and G12 correspond to the first layer design patterns D11 and D12, and the second layer imaging pattern G21 corresponds to the second layer design pattern D21.

  These imaging screens G are imaged by the area-type imaging device 18 and taken into the control device 6, where the control device 6 processes the first layer imaging patterns G11 and G12 and the second layer imaging pattern G21.

  The imaging screen G in FIG. 4 is shown in FIG. 5A, and the design screen D3 in FIG. 3 is shown again in FIG. 5B for comparison. In the control device 6, the imaging screen G and the design screen D3 are compared (collated). As a result of the comparison, the control device 6 compares the edge E3 of the first layer imaging pattern G12 in the imaging screen G with the edge E1 of the first layer design pattern D12 in the design screen D3, and the first layer imaging pattern G12. Is shifted in the Y-axis direction above the first layer design pattern D12, and the second-layer imaging pattern G21 is determined to be shifted in the Y-axis direction lower than the second layer design pattern D21. The amount of displacement is calculated. The calculation of the positional deviation amount is performed by subtracting the coordinate data of the edge E1 of the first layer design pattern D12 from the coordinate data of the edge E3 of the first layer imaging pattern G12, and the edge of the second layer imaging pattern G21. It can be obtained by subtracting the coordinate data of the edge E2 of the second layer design pattern D21 from the coordinate data of E4.

  Then, as shown in FIG. 6, the design measurement designated points E1 and E2 are changed to new measurement designated points E3 and E4 from the calculated values.

  In addition, although the imaging pattern of the 1st layer and 2nd layer which were shown in embodiment did not overlap in the layer direction, it has the pattern part which does not overlap with the pattern part which the imaging pattern of the 1st layer and the 2nd layer overlaps The case will be described with reference to FIG.

   In FIG. 7A, the first layer design patterns D13 and D14 and the second layer design patterns D22 and D23 partially overlap. The design measurement designated points are E1 and E2. The measurement designated point E1 is the upper edge in the Y-axis direction of the first layer design pattern D14, and the measurement designated point E2 is the lower edge in the Y-axis direction of the second layer design pattern D22.

  In FIG. 7B, the first layer imaging patterns G13 and G14 and the second layer imaging patterns G22 and G23 partially overlap. Even if the imaging patterns G22 and G23 of the second layer are misaligned, the measurement designated points are the same as those in FIGS. 2 to 6 from the originally designed measurement designated points E1 and E2 corresponding to the misalignment. Since new measurement designated points E3 and E4 are generated by performing comparison and calculation, the upper edge in the Y-axis direction of the second-layer imaging pattern G23 is displaced upward in the Y-axis direction and approaches the measurement designated point E2. However, the upper edge in the Y-axis direction of the imaging pattern G23 of the second layer is not mistaken for the measurement designated point E4 ′.

  In the above embodiment, the pattern has two layers, but the pattern may be three or more layers. In the case of three or more n layers, any one layer is used as a reference, and the reference layer and other layers It is preferable to calculate the relative deviation amount with respect to the first layer up to n layers, and when the calculation of the relative deviation amount of all the layers is completed, the coordinates of the measurement designated point are corrected and the dimension measurement is performed.

  The dimension measuring apparatus according to the embodiment, in terms of hardware, includes a camera mechanism including an area-type imaging device 18 and a high-speed autofocus mechanism 20 in the imaging device 4, a computer of the control device 16, a display of the control device 16, and the like. Output devices such as a display device and a printer, and driving mechanisms such as an imaging base 8 and a moving table 12 in the imaging device 4.

  As shown in FIG. 8, the dimension measuring apparatus according to the embodiment includes, in terms of software, an imaging screen generation unit 30 that generates the imaging screen data of FIG. 4 from the imaging output of the imaging unit shown in FIG. Design screen data storage unit 31, image capture screen G from image capture screen generation unit 30, collation operation unit 32 that collates and calculates design screen D stored in design screen data storage unit 31, and collation operation unit A positional deviation amount computing unit 33 for computing the positional deviation amount from the output of 32, a measurement designated point storage unit 34 for storing measurement designated points, a positional deviation amount computing unit 33, and a measurement designated point storage unit 34; A measurement designated point generation unit 35 that newly generates a measurement designated point from both outputs of the output, a dimension measurement unit 36 that measures the dimension of the measurement object from the output of the measurement designated point generation unit 35, and outputs the measurement result; Is provided.

FIG. 1 is a diagram showing a schematic configuration of a dimension measuring apparatus used in an embodiment of the present invention. FIG. 2 is a diagram showing design pattern data of each layer on the design. FIG. 3 is a diagram showing design pattern data obtained by synthesizing the design pattern data of each layer. FIG. 4 is a diagram showing imaging pattern data. FIG. 5 is a diagram for explaining collation between the imaging pattern data of FIG. 4 and the design pattern data of FIG. FIG. 6 is a diagram for explaining the correction of the measurement position. FIG. 7 is a diagram for explaining collation between patterns in which overlapping portions and non-overlapping portions exist in the pattern between layers and correction of the measurement position. FIG. 8 is a functional block diagram of the dimension measuring apparatus according to the embodiment.

Explanation of symbols

2 Dimensional measuring device 4 Imaging device 6 Control device 8 Imaging base 10 Guide rail 12 Moving table 14 Linear scale 16 Imaging stand 18 Area type imaging device 22 Substrate D1, D2, D3 Design screen D11-D21 Design pattern G Imaging screen G11- G21 Imaging pattern

Claims (6)

A dimension measuring method for a measurement object in which a pattern is formed at least twice,
A first step of comparing the design pattern of each layer with each layer of the imaging pattern of the measurement object;
A second step of calculating a relative deviation amount from the design pattern of each layer in the imaging pattern of each layer of the measurement object from the comparison result of the first step;
A dimension measuring method comprising:   2. The dimension measuring method according to claim 1, further comprising a third step in which the relative deviation obtained in the second step is used for measuring the dimension of the measurement object.   In the first step, the comparison between the design pattern and the imaging pattern is a comparison of measurement positions determined at arbitrary positions of the design pattern and the imaging pattern, and the relative deviation amount is the relative deviation amount between the two measurement positions. The dimension measuring method according to claim 1 or 2, characterized by the above-mentioned.   The dimension measuring method according to claim 3, wherein the measurement position is an edge of a pattern.   5. The method according to claim 1, wherein when there are three or more patterns, an arbitrary one layer is used as a reference, and a relative shift amount between the reference layer and another layer is calculated. The dimension measuring method as described.   6. A dimension measuring apparatus, comprising a computer program for executing each step of the dimension measuring method according to claim 1.

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