Alignment method, alignment device, and program

Abstract

To provide a positioning method, positioning device, and program that can further improve the accuracy of alignment. [Solution] The alignment method includes sampling the transmitted light signal with respect to a first direction and a second direction in which the first array extends on the first object stacked with the second object; sampling the transmitted light signal with respect to a first direction and a second direction in which the second array extends on the second object stacked with the first object; and adding the signal intensity of the transmitted signal sampled with respect to the first direction with respect to the second direction, wherein the first array and the second array have a periodic structure such that the transmitted signal with the added signal intensity with respect to the second direction approximates a sine wave with respect to the first direction.

Description

Technical Field

[0001] The present invention relates to an alignment method, an alignment apparatus, and a program.

Background Art

[0002] An alignment technique using moiré fringes generated by superimposing two patterns arranged at different pitches from each other is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In conventional methods, the patterns for generating moiré fringes each need to be arranged with a very small period, and furthermore, a high-magnification lens having a high NA (Numerical Aperture) is required for analysis. As a result, the depth of focus becomes shallow, making it difficult to focus on the pattern on the back surface of the substrate. That is, in conventional methods, the alignment accuracy with respect to the pattern on the back surface of the substrate may be lowered.

[0005] The present invention has been made in consideration of such circumstances, and an object thereof is to provide an alignment method, an alignment apparatus, and a program that can further improve alignment accuracy.

Means for Solving the Problem

[0006] A first example of the present invention includes stacking a first object on which a first array having a first periodic structure is formed and a second object on which a second array having the first periodic structure is formed; irradiating the stacked first and second objects with light; detecting a first signal which is the signal of the light that has passed through the first array formed on the first object; detecting a second signal which is the signal of the light that has passed through the second array formed on the second object; and calculating the positional displacement of the stacked first and second objects based on the first and second signals, wherein the first array is formed on either the first surface of the first object or the second surface facing the first surface, and the second array is formed on the third surface of the second object or the fourth surface facing the third surface that does not face the first object, and a plurality of the first signals are sampled with respect to a first direction which is one direction in which the first array extends on the first object and a second direction which is the other direction in which the first array extends on the first object. The alignment method further includes sampling a plurality of second signals with respect to a first direction, which is one direction in which the second array extends on the second object, and a second direction, which is the other direction in which the second array extends on the second object; adding the signal intensity of the first signal sampled with respect to the second direction with respect to the second direction, based on the signal intensity of the first signal sampled with respect to the second direction; and adding the signal intensity of the second signal sampled with respect to the first direction with respect to the second direction, based on the signal intensity of the second signal sampled with respect to the second direction, wherein the first periodic structure of the first array has a structure such that the first signal with the added signal intensity with respect to the second direction approximates a sine wave with respect to the first direction, and the first periodic structure of the second array has a structure such that the second signal with the added signal intensity with respect to the second direction approximates a sine wave with respect to the first direction.

[0007] A second example of the present invention is the alignment method of the first example, wherein the first periodic structure of the first array and the first periodic structure of the second array have a structure that satisfies formula (1) described below, where y represents the signal intensity of the sampled first signal or second signal, x represents the sampling position of the first signal or second signal with respect to the first direction, λ represents the wavelength of the approximated sine wave, and a, b, c, d, e, p, M, and N are arbitrary parameters.

[0008] A third example of the present invention further includes sampling the first signal and the second signal using an image sensor in which a plurality of pixels are arranged in two dimensions, wherein the sizes of the first array and the second array are larger than the size of the pixels.

[0009] A fourth example of the present invention is the alignment method of the third example, wherein, among the sampled first signals, the distance from the sampling position of a first signal whose signal intensity is less than a first threshold to the sampling position of a first signal whose signal intensity is greater than or equal to a second threshold is greater than or equal to the first threshold exceeds the pixel pitch, which is the distance between pixels, or, among the sampled second signals, the distance from the sampling position of a second signal whose signal intensity is less than a first threshold to the sampling position of a second signal whose signal intensity is greater than or equal to the second threshold exceeds the pixel pitch.

[0010] A fifth example of the present invention is a stacked first object and a second object, comprising: an illumination unit that irradiates light onto the first object, which has a first array having a first periodic structure formed on it, and the second object, which has a second array having the first periodic structure formed on it; a detection unit that detects a first signal, which is the signal of the light that has passed through the first array formed on the first object, and a second signal, which is the signal of the light that has passed through the second array formed on the second object; and a calculation unit that calculates the misalignment of the stacked first object and the second object based on the first signal and the second signal, wherein the first array is formed on either the first surface of the first object or the second surface facing the first surface, and the second array is formed on the third surface of the second object or the fourth surface facing the third surface, which is the surface that does not face the first object, and the calculation unit determines a plurality of the first arrays with respect to a first direction, which is one direction in which the first array extends on the first object, and a second direction, which is the other direction in which the first array extends on the first object. The alignment device samples a signal and samples a plurality of second signals with respect to a first direction, which is one direction in which the second array extends on the second object, and a second direction, which is the other direction in which the second array extends on the second object. Based on the signal intensity of the first signal sampled with respect to the second direction, the signal intensity of the first signal sampled with respect to the first direction is added with respect to the second direction. Based on the signal intensity of the second signal sampled with respect to the second direction, the signal intensity of the second signal sampled with respect to the first direction is added with respect to the second direction. The first periodic structure of the first array is such that the first signal, with the added signal intensity in the second direction, approximates a sine wave with respect to the first direction, and the first periodic structure of the second array is such that the second signal, with the added signal intensity in the second direction, approximates a sine wave with respect to the first direction.

[0011] A sixth example of the present invention is a program for a computer to execute, comprising: irradiating a stacked first object and a second object with light onto the first object, the first object having a first array having a first periodic structure formed on it, and the second object having a second array having the first periodic structure formed on it; detecting a first signal, which is the signal of the light that has passed through the first array formed on the first object; detecting a second signal, which is the signal of the light that has passed through the second array formed on the second object; and calculating the misalignment of the stacked first object and second object based on the first signal and the second signal, wherein the first array is formed on either the first surface of the first object or the second surface facing the first surface, and the second array is formed on the third surface of the second object or the fourth surface facing the third surface that does not face the first object, and a plurality of the first arrays are formed with respect to a first direction, which is one direction in which the first array extends on the first object, and a second direction, which is the other direction in which the first array extends on the first object. The program further includes sampling a signal; sampling a plurality of the second signals with respect to a first direction, which is one direction in which the second array extends on the second object, and a second direction, which is the other direction in which the second array extends on the second object; adding the signal intensity of the first signal sampled with respect to the second direction with respect to the second direction, based on the signal intensity of the first signal sampled with respect to the second direction; and adding the signal intensity of the second signal sampled with respect to the first direction with respect to the second direction, based on the signal intensity of the second signal sampled with respect to the second direction, wherein the first periodic structure of the first array is such that the first signal, with its signal intensity added with respect to the second direction, approximates a sine wave with respect to the first direction, and the first periodic structure of the second array is such that the second signal, with its signal intensity added with respect to the second direction, approximates a sine wave with respect to the first direction. [Effects of the Invention]

[0012] As shown in the example above, the accuracy of the alignment can be further improved. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows an example of the configuration of the alignment device 1 according to this embodiment. [Figure 2] This figure shows an example of the configuration of the first object OB1 and the second object OB2 according to this embodiment. [Figure 3] This figure shows an example of the configuration of the first object OB1 and the second object OB2 according to this embodiment. [Figure 4] This figure shows an example of a pattern P2 formed on the second object OB2. [Figure 5] This is an enlarged view of the alignment marks WA and WB. [Figure 6] This figure shows an example of a pattern P1 formed on the first object OB1. [Figure 7] This is a magnified view of the alignment marks XA and XB. [Figure 8] This diagram provides a more detailed explanation of the structure of the precision alignment marks HW1 and HX1. [Figure 9] This figure shows an example of the configuration of the control device 100 according to this embodiment. [Figure 10] This flowchart shows an example of a series of processing steps of the alignment device 1 according to this embodiment. [Figure 11] This figure shows an example of an image of transmitted light from the first object OB1 and the second object OB2. [Figure 12] This diagram schematically illustrates the process from signal detection to calculation of XY position deviation. [Figure 13] This diagram illustrates an example of sine wave fitting. [Figure 14] This diagram illustrates an example of XY position deviation. [Figure 15] This figure shows an example of variations in the shape of the array. [Figure 16]FIG. 1 is a diagram illustrating an example of sine wave fitting when an array has a rhombus shape. [Figure 17] FIG. 2 is a diagram illustrating an example of sine wave fitting when an array has a rhombus shape. [Figure 18] FIG. 3 is a diagram illustrating another example of variations in the shape of an array. [Figure 19] FIG. 4 is a diagram illustrating an example of sine wave fitting when an array has a trapezoidal shape. [Figure 20] FIG. 5 is a diagram illustrating an example of sine wave fitting when an array has a trapezoidal shape. [Figure 21] FIG. 6 is a diagram illustrating another example of variations in the shape of an array. [Figure 22] FIG. 7 is a diagram illustrating an example of sine wave fitting when an array has an octagonal shape. [Figure 23] FIG. 8 is a diagram illustrating an example of sine wave fitting when an array has an octagonal shape. [Figure 24] FIG. 9 is a diagram illustrating another example of variations in the shape of an array. [Figure 25] FIG. 10 is a diagram illustrating an example of sine wave fitting when an array has a random shape. [Figure 26] FIG. 11 is a diagram illustrating an example of sine wave fitting when an array has a random shape. [Figure 27] FIG. 12 is a diagram illustrating another example of variations in the shape of an array. [Figure 28] FIG. 13 is a diagram illustrating an example of sine wave fitting when an array has a triangular shape. [Figure 29] FIG. 14 is a diagram illustrating an example of sine wave fitting when an array has a triangular shape. DETAILED DESCRIPTION OF EMBODIMENTS

[0014] Hereinafter, embodiments of an alignment method, an alignment apparatus, and a program according to the present invention will be described with reference to the drawings.

[0015] [Example configuration of a positioning device (laminated body manufacturing device)] Figure 1 shows an example of the configuration of the alignment device 1 according to this embodiment. The alignment device 1 is also a laminate manufacturing apparatus 1. As shown in Figure 1, the alignment device 1 includes a camera 20, a fixed stage 30, an XYZθ axis movable stage 40, an illumination device (light source) 50, and a control device 100.

[0016] In the diagram, X represents one direction (axis) that forms the horizontal plane, Y represents the other direction (axis) that forms the horizontal plane, and Z represents the vertical direction perpendicular to the horizontal plane (vertical axis). In other words, X represents the width direction, Y represents the depth direction, and Z represents the height direction.

[0017] The alignment device 1 stacks a first object OB1 and a second object OB2, irradiates light onto the first object OB1 and the second object OB2 from below or above, detects the transmitted light that has passed through the first object OB1 and the second object OB2 as an electrical signal, calculates the positional misalignment between the first object OB1 and the second object OB2 based on the transmitted light signal, and adjusts the position of one or both of the first object OB1 and the second object OB2 based on that positional misalignment.

[0018] The first object OB1 is, for example, a photomask, a mold, or a second substrate (second wafer). The second object OB2 is a substrate (wafer) and may be, for example, various types of glass, silicon, or compound semiconductors. The laminate of these first object OB1 and second object OB2 may be used in the manufacture of any of the following: an optoelectronic semiconductor device, a semiconductor device, or an optical device.

[0019] The alignment device 1 typically adjusts the position of the substrate (second object OB2) relative to the first object OB1, such as a photomask or mold, when stacking the first object OB1 and the second object OB2. In other words, of the two objects OB1 and OB2, only the second object OB2 is subject to alignment. Patterns for alignment during stacking are formed on both the first object OB1 and the second object OB2. Details of each pattern will be described later.

[0020] The camera 20 includes an image sensor in which multiple pixels are arranged in two dimensions. The camera 20 is positioned, for example, above the fixed stage 30, the XYZθ axis movable stage 40, and the illumination device 50. The camera 20 detects transmitted light, which is light irradiated from the illumination device 50 and passed through the first object OB1 and the second object OB2, via the lens 22. The bit depth of the camera 20 can be 8 bits or more, and more preferably 12 bits or more. The numerical aperture (NA) of the lens 22, that is, the observation magnification of the camera 20, may be a low magnification such as 0.5x, 1.0x, or 2.0x.

[0021] The fixed stage 30, for example, holds the first object OB1 in accordance with the control of the control device 100, and stacks the first object OB1 on the second object OB2 placed on the XYZθ axis movable stage 40.

[0022] The second object OB2 is placed on the XYZθ axis movable stage 40. The XYZθ axis movable stage 40 moves the placed second object OB2, for example, in accordance with the control of the control device 100. Move in the horizontal direction (XY direction), the vertical direction (Z direction), and the rotational direction in the horizontal plane (θ direction).

[0023] The illumination device 50 is positioned, for example, below the camera 20, the fixed stage 30, and the XYZθ-axis movable stage 40. Alternatively, the illumination device 50 may be positioned inside the XYZθ-axis movable stage 40. The illumination device 50 irradiates the stacked first object OB1 and second object OB2 with light from below the XYZθ-axis movable stage 40. For example, the illumination device 50 may be a light source capable of uniformly illuminating the imaging area of ​​the camera 20. Specifically, the illumination device 50 may irradiate near-infrared light with a wavelength of about 1050 [nm]. Note that if the camera 20 is positioned below the fixed stage 30, the XYZθ-axis movable stage 40, and the illumination device 50, the illumination device 50 may be positioned above them. In this case, the illumination device 50 irradiates the stacked first object OB1 and second object OB2 with light from above.

[0024] The control device 100 controls, for example, the camera 20, the fixed stage 30, the XYZθ axis movable stage 40, and the lighting device 50 to stack and align the first object OB1 and the second object OB2.

[0025] In addition to the camera 20, fixed stage 30, XYZθ axis movable stage 40, lighting device 50, and control device 100 described above, the alignment device 1 may also include a coating device 60, an ultraviolet irradiation device 70, and the like.

[0026] The coating apparatus 60, in accordance with the control of the control device 100, applies, for example, an ultraviolet-curable resin (ultraviolet-curable visible fluorescent liquid) containing a fluorescent dye between the first object OB1 and the second object OB2.

[0027] The ultraviolet irradiation device 70 may, in accordance with the control of the control device 100, irradiate the first object OB1 and the second object OB2, to which the ultraviolet-curable resin has been applied, with ultraviolet light to cure the ultraviolet-curable resin. As a result, the laminated first object OB1 and the second object OB2 are bonded together by the ultraviolet-curable resin, and a laminate containing the first object OB1 and the second object OB2 is manufactured.

[0028] [Composition of the first and second objects (laminated structure)] Next, the configurations of the first object OB1 and the second object OB2 will be described. Figures 2 and 3 show examples of the configurations of the first object OB1 and the second object OB2 according to this embodiment.

[0029] In this embodiment, pattern P1 is formed on the first object OB1, and pattern P2 is formed on the second object OB2.

[0030] For example, as shown in Figure 2, pattern P1 is formed on the back side of the first object OB1, which is the side facing the second object OB2. Pattern P1 may be formed, for example, by etching away a portion of a chromium film or the like deposited on the back side. The front surface of the first object OB1 is an example of a "first surface," and the back surface of the first object OB1 is an example of a "second surface."

[0031] On the other hand, pattern P2 is formed on the back side of the second object OB2, which is the side that does not face the first object OB1. Pattern P2 may be formed, for example, by etching away a portion of the metallic light-shielding film deposited on the back side. The front surface of the second object OB2 is an example of a "third surface," and the back surface of the second object OB2 is an example of a "fourth surface."

[0032] Furthermore, as shown in Figure 3, pattern P1 may be formed on the front side of the first object OB1, which is the side that does not face the second object OB2. Even if pattern P1 is formed on the front surface of the first object OB1, pattern P2 is formed on the back side of the second object OB2.

[0033] Below, we will describe the pattern P2 formed on the second object OB2 before describing the pattern P1 formed on the first object OB1. Figure 4 shows an example of the pattern P2 formed on the second object OB2.

[0034] Pattern P2 includes alignment marks WA and WB. The alignment marks WA and WB are formed on the outer surface (near the outer edge) of the front or back surface of the second object OB2. By forming the alignment marks WA and WB on the outside, the positional misalignment in the rotational direction (θ direction) can be adjusted with greater precision. A circuit pattern, for example, may be formed between the alignment marks WA and WB.

[0035] Figure 5 is a magnified view of the alignment marks WA and WB. The alignment marks WA and WB include the coarse alignment mark MW and the precision alignment mark HW1.

[0036] The rough alignment marks MW are marks used to roughly align the positions of the first object OB1 and the second object OB2. The rough alignment marks MW may be, for example, cross-shaped marks, and two of them may be formed at diagonal positions separated from each other.

[0037] The precision alignment mark HW1 is a mark used to precisely align the positions of the first object OB1 and the second object OB2.

[0038] The precision alignment mark HW1 may have a periodic structure in which arrays of a predetermined shape are arranged at intervals of period p1. The arrays are typically triangular, as shown in the figure, but are not limited to this, and may be of various other shapes such as rhombic, trapezoidal, or octagonal. The period p1 may be, for example, about 45.0 [μm].

[0039] The period p1 of the precision alignment mark HW1 should be at least 5 times the pixel size of the camera 20, and more preferably 9 times or more.

[0040] Next, we will explain the pattern P1 formed on the first object OB1. Figure 6 shows an example of the pattern P1 formed on the first object OB1.

[0041] Pattern P1 includes alignment marks XA and XB. The alignment marks XA and XB are formed on the outer surface (near the outer edge) of the front or back surface of the first object OB1. By forming the alignment marks XA and XB on the outside, the positional misalignment in the rotational direction (θ direction) can be adjusted with greater precision. A circuit pattern, for example, may be formed between the alignment marks XA and XB.

[0042] Figure 7 is a magnified view of the alignment marks XA and XB. The alignment marks XA and XB include the coarse alignment mark MX and the precision alignment mark HX1.

[0043] The rough alignment mark MX, like the rough alignment mark MW mentioned above, is a mark used to roughly align the positions of the first object OB1 and the second object OB2.

[0044] The rough alignment marks MX may be, for example, square-shaped marks, and like the rough alignment marks MW, two of them are formed at diagonal positions separated from each other.

[0045] The precision alignment mark HX1, like the precision alignment mark HW1 described above, is a mark used to precisely align the positions of the first object OB1 and the second object OB2.

[0046] The precision alignment mark HX1, like the precision alignment mark HW1, may have a periodic structure in which, for example, an array of predetermined shapes is arranged at intervals of period p1.

[0047] The period p1 of the precision alignment mark HX1 should be at least 5 times the pixel size of the camera 20, and more preferably 9 times or more.

[0048] Details regarding the periodic structure of these precision alignment marks HX1 and HW1, which approximates a sine wave, will be described later.

[0049] When the first object OB1 and the second object OB2 are stacked, the precision alignment marks HX1 formed as pattern P1 on the first object OB1 and the precision alignment marks HW1 formed as pattern P2 on the second object OB2 are formed so that they do not overlap when viewed from above or below (i.e., with respect to the Z direction).

[0050] Patterns P1 and P2 may be formed, for example, using photolithography or electron beam lithography, which transfers a pattern formed on one to the other.

[0051] Specifically, if a precision alignment mark HX1 is first formed on the first object OB1 as part of pattern P1, that precision alignment mark HX1 may be transferred to the second object OB2 as a precision alignment mark HW1. Also, if a precision alignment mark HW1 is first formed on the second object OB2 as part of pattern P2, that precision alignment mark HW1 may be transferred to the first object OB1 as a precision alignment mark HX1.

[0052] Figure 8 is a diagram illustrating the structure of precision alignment marks HW1 and HX1 in more detail. As described above, precision alignment marks HW1 and HX1 consist of triangular or other arrangements arranged at intervals of period p1. The arrangement contained in precision alignment mark HW1 is an example of a "first arrangement," and the arrangement contained in precision alignment mark HX1 is an example of a "second arrangement."

[0053] The precision alignment mark HX1 has a periodic structure in which multiple arrays are arranged such that the signal sampled in the X direction, for example, of the two directions (X and Y) that form a two-dimensional plane, approximates a sine wave.

[0054] Similarly, the precision alignment mark HW1 has a periodic structure in which multiple arrays are arranged such that the signal sampled in the X direction, for example, of the X and Y directions that form a two-dimensional plane, approximates a sine wave.

[0055] The size of the arrays included in these precision alignment marks HX1 and HW1 is larger than the size of the pixels in camera 20.

[0056] [Control device configuration] Next, the configuration of the control device 100 will be described. Figure 9 is a diagram showing an example of the configuration of the control device 100 according to this embodiment. The control device 100 includes, for example, a communication interface 110, an input interface 120, an output interface 130, a storage unit 140, and a processing unit 150.

[0057] The communication interface 110 includes, for example, a NIC (Network Interface Card) or a wireless communication module including a receiver and a transmitter. The communication interface 110 communicates with external devices via a network such as a LAN (Local Area Network) or a WAN (Wide Area Network). External devices include, for example, the camera 20, fixed stage 30, XYZθ axis movable stage 40, lighting device 50, coating device 60, and ultraviolet irradiation device 70 mentioned above.

[0058] The input interface 120 receives various input operations from the user, converts the received input operations into electrical signals, and outputs them to the processing unit 150. For example, the input interface 120 includes a mouse, keyboard, trackball, switch, button, joystick, touch panel, etc. The input interface 120 may also be a voice user interface that accepts audio input, such as from a microphone.

[0059] The output interface 130 includes, for example, a display and a speaker. The display shows images generated by the processing unit 150, as well as a GUI (Graphical User Interface) for accepting various input operations from the user. For example, the display may be an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescence) display. The speaker outputs the information input from the processing unit 150 as sound.

[0060] The storage unit 140 is implemented using, for example, an HDD (Hard Disk Drive), flash memory, EEPROM (Electrically Erasable Programmable Read Only Memory), ROM (Read Only Memory), or RAM (Random Access Memory). The storage unit 140 stores various programs such as firmware and application programs.

[0061] The processing unit 150 includes, for example, an acquisition unit 151, an image processing unit 152, a calculation unit 153, and an output control unit 154. The combination of the camera 20 and the image processing unit 152 described above is an example of a "detection unit".

[0062] The components of the processing unit 150 are realized, for example, by a processor such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit) executing a program stored in the memory unit 140. Furthermore, some or all of the components of the processing unit 150 may be realized by hardware such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or SOC (System On Chip), or by the cooperation of software and hardware.

[0063] [Processing flow of the alignment device] The following describes the sequence of operations of the alignment device 1 in accordance with the flowchart. Figure 10 is a flowchart showing an example of the sequence of operations of the alignment device 1 according to this embodiment. The operations in this flowchart may be repeated at a predetermined interval, for example, when the misalignment between the first object OB1 and the second object OB2 is within a certain range.

[0064] First, the image processing unit 152 detects the precision alignment mark HX1 and the precision alignment mark HW1 from the transmitted light images of the first object OB1 and the second object OB2 (step S100).

[0065] Figure 11 shows an example of a transmitted light image of the first object OB1 and the second object OB2. As described above, the precision alignment marks HX1 and HW1 are pre-patterned so that they do not overlap with each other, and therefore they are detected without overlapping in the transmitted light image.

[0066] Next, the image processing unit 152 samples a signal indicating the transmitted light of the precision alignment mark HX1 with period p1 (hereinafter referred to as signal W11) and a signal indicating the transmitted light of the precision alignment mark HW1 with period p1 (hereinafter referred to as signal W12) (step S102). Signal W11 is an example of a "first signal", and signal W12 is an example of a "second signal".

[0067] For example, the image processing unit 152 samples multiple signals W11 in the X and Y directions, respectively, where the precision alignment mark HX1 extends on the first object OB1. The X direction may be interpreted as the longitudinal direction, and the Y direction as the transverse direction. Through this processing, the transmitted light (i.e., signal W11) of the precision alignment mark HX1 can be detected evenly as a two-dimensional distribution in the two-dimensional plane (XY plane). The X direction is an example of a "first direction," and the Y direction is an example of a "second direction."

[0068] In this case, the image processing unit 152 samples the signal W11 such that the distance from the sampling position of a signal W11 whose signal intensity (which may be read as brightness value) is less than the first threshold to the sampling position of a signal W11 whose signal intensity is greater than the first threshold (a second threshold) exceeds the pixel pitch. The pixel pitch is the distance between pixels of the camera 20.

[0069] The image processing unit 152 samples multiple signals W12 in the X and Y directions, respectively, where the precision alignment mark HW1 extends on the second object OB2. Through this process, the transmitted light (i.e., signal W12) of the precision alignment mark HW1 can be detected evenly as a two-dimensional distribution in the two-dimensional plane (XY plane).

[0070] In this case, the image processing unit 152 samples the signal W12 such that the distance from the sampling position of the signal W12 with a signal intensity less than the first threshold to the sampling position of the signal W12 with a signal intensity of 2 or greater exceeds the pixel pitch.

[0071] Next, the calculation unit 153 adds the signal strength of the signal sampled in the other direction to the signal strength of the signal sampled in the other direction (step S104).

[0072] For example, the calculation unit 153 adds the signal intensity of the signal W11 sampled in the X direction to the signal intensity of the signal W11 sampled in the Y direction, based on the signal intensity of the signal W11 sampled in the Y direction. Through this process, multiple signals W11 detected as a two-dimensional distribution (distribution in the XY plane) are replaced with a one-dimensional distribution signal W11 (a signal W11 distributed on the X axis).

[0073] Similarly, the calculation unit 153 adds the signal intensity of the signal W12 sampled in the X direction to the signal intensity of the signal W12 sampled in the Y direction, based on the signal intensity of the signal W12 sampled in the Y direction. Through this process, the multiple signals W12 detected as a two-dimensional distribution (distribution in the XY plane) are replaced with a one-dimensional distribution of signal W12 (signal W12 distributed on the X axis).

[0074] Next, the calculation unit 153 fits the signal W11 (the signal distributed on the X axis), which has its signal strength added in the Y direction, and the signal W12 (the signal distributed on the X axis), which has its signal strength added in the Y direction, to a sine wave (step S106).

[0075] Next, the calculation unit 153 calculates the XY positional deviation between the first object OB1 and the second object OB2 based on the signals W11 and W12, which are fitted to sine waves (step S108). The XY positional deviation is the difference (distance) between the positions of the objects in the XY plane. This completes the series of processes in the flowchart.

[0076] The precision alignment mark HW2 may have a periodic structure in which an array of predetermined shapes is arranged at intervals of period p2. Period p2 may be different from period p1, for example, it may be about 46.0 [μm].

[0077] The precision alignment mark HX2, like the precision alignment mark HW2, may have a periodic structure in which, for example, an array of predetermined shapes is arranged at intervals of period p2.

[0078] The size of the arrays included in these precision alignment marks HX2 and HW2 is also larger than the size of the pixels in camera 20.

[0079] Figure 12 schematically illustrates the process from signal detection to calculation of XY position deviation. Signal W11 is detected from the transmitted light of precision alignment mark HX1 with period p1, and signal W12 is detected from the transmitted light of precision alignment mark HW1 with period p1. The signal strengths of these signals W11 and W12 are added together in the Y direction and fitted to a sine wave. Then, the XY position deviation is calculated from the sinusoidal-fitted signals W11 and W12.

[0080] Figure 13 shows an example of sinusoidal fitting. As shown in the figure, signals W11 and W12, whose signal strengths are added together in the Y direction, are fitted to a sine wave, for example.

[0081] Figure 14 shows an example of XY position deviation. For example, the calculation unit 153 calculates the deviation between signals W11 and W12 (e.g., the distance between peaks) for each period. In this case, the calculation unit 153 may calculate the deviation for each period and use the average value of the deviations for all periods as the deviation between signals W11 and W12. The calculation unit 153 then calculates the deviation between signals W11 and W12 as the XY position deviation between the first object OB1 and the second object OB2.

[0082] The calculation unit 153 may calculate the deviation between signals W21 and W22 instead of calculating the deviation between signals W11 and W12, and use this as the deviation of the XY positions between the first object OB1 and the second object OB2.

[0083] Signal W21 is a signal indicating transmitted light from the precision alignment mark HX2 with period p2. Signal W22 is a signal indicating transmitted light from the precision alignment mark HW2 with period p2.

[0084] Although the precision alignment marks HX1, HX2, HW1, and HW2 have been described as having a structure in which arrays of a predetermined shape are arranged in the X direction at intervals of period p1 or p2, they are not limited to this. For example, the precision alignment marks HX1, HX2, HW1, and HW2 may have a structure in which arrays of a predetermined shape are arranged in the Y direction at intervals of period p1 or p2. In this case, not only the X position deviation between the first object OB1 and the second object OB2 can be calculated, but also the Y position deviation. As a result, the first object OB1 and the second object OB2 can be precisely aligned on the XY plane.

[0085] [Variations in the shape of the array] The following describes some variations of the predetermined shaped arrays included in the precision alignment marks HX1, HX2, HW1, and HW2. Figure 15 shows an example of a variation in the shape of the array. As shown in the figure, the array may have a rhombus shape. The signal showing the transmitted light from precision alignment marks HX1, HX2, HW1, and HW2 having such a rhombus shape can be fitted to a sine wave.

[0086] Figures 16 and 17 illustrate an example of sinusoidal fitting when the array is rhombic in shape. As shown in the figures, when the signal intensities of signals W11, W12, W21, and W22, which represent the transmitted light from precision alignment marks HX1, HX2, HW1, and HW2, which have a rhombic shape, are added together in the Y direction, each approximates a sine wave.

[0087] Figure 18 shows another example of a variation in the shape of the array. As shown in the figure, the array may have a trapezoidal shape. The signals showing the transmitted light from precision alignment marks HX1, HX2, HW1, and HW2 having such a trapezoidal shape can be fitted to a sine wave.

[0088] Figures 19 and 20 illustrate an example of sinusoidal fitting when the array is trapezoidal in shape. As shown in the figures, when the signal intensities of signals W11, W12, W21, and W22, which represent the transmitted light from the trapezoidal precision alignment marks HX1, HX2, HW1, and HW2, are added together in the Y direction, each approximates a sine wave.

[0089] Figure 21 is a diagram illustrating another example of a variation in the shape of the array. As shown in the figure, the array may have an octagonal shape. The signals showing the transmitted light from precision alignment marks HX1, HX2, HW1, and HW2 having such an octagonal shape can be fitted to a sine wave.

[0090] Figures 22 and 23 illustrate an example of sinusoidal fitting when the array is octagonal in shape. As shown in the figures, when the signal intensities of signals W11, W12, W21, and W22, which represent the transmitted light from the octagonal precision alignment marks HX1, HX2, HW1, and HW2, are added together in the Y direction, each approximates a sine wave.

[0091] Figure 24 is a diagram illustrating another example of the variation in the shape of the array. As shown in the figure, the array may have a random shape that forms a gradient pattern. The signals showing the transmitted light from precision alignment marks HX1, HX2, HW1, and HW2 having such random shapes can be fitted to a sine wave.

[0092] Figures 25 and 26 illustrate an example of sinusoidal fitting when the array has a random shape. As shown in the figures, when the signal intensities of signals W11, W12, W21, and W22, which represent the transmitted light from precision alignment marks HX1, HX2, HW1, and HW2, which have a random shape forming a gradient pattern, are added together in the Y direction, each approximates a sine wave.

[0093] Figure 27 shows another example of a variation in the shape of the array. As shown in the figure, the array may have a triangular shape. Signals showing the transmitted light from precision alignment marks HX1, HX2, HW1, and HW2 having such a triangular shape can be fitted to a sine wave.

[0094] Figures 28 and 29 illustrate an example of sinusoidal fitting when the array is triangular in shape. As shown in the figures, when the signal intensities of signals W11, W12, W21, and W22, which represent the transmitted light from the triangular precision alignment marks HX1, HX2, HW1, and HW2, are added together in the Y direction, each approximates a sine wave.

[0095] As illustrated above, several variations have been demonstrated, but in all cases, the shape of the sampled signal in the X direction approximates a sine wave.

[0096] [Mathematical approach to the shape of arrays] The shape of the array will be explained in more detail below, including mathematical formulas. In order to fit the signal in the X direction, which is obtained by adding the signal strength in the Y direction, to a sine wave, for example, the precision alignment marks HX1, HX2, HW1, and HW2 have a structure that satisfies formula (1).

[0097]

number

[0098] Here, y represents the signal intensity of the sampled signal W11, W12, W21, or W22; x represents the sampling position of the signal W11, W12, W21, or W22 in the X direction; λ represents the wavelength of the approximated sine wave; and a, b, c, e, d, p, M, and N are arbitrary parameters.

[0099] The parameters a, b, c, d, p, M, and N satisfy the following numerical conditions to form a rectangular array. In this embodiment, the array will have a shape other than a rectangle. In other words, the parameters will be such that they do not satisfy the following numerical conditions.

[0100] a:0 b: All (including positive and negative, zero, and decimals) c:1 d: All (including positive and negative numbers, zero, and decimals) p:0 M: 0 or greater, integers only. N: 1 or greater, integers only.

[0101] According to the embodiment described above, the alignment device 1 stacks a first object OB1 (e.g., a photomask) and a second object OB2 (e.g., a wafer).

[0102] At least precision alignment marks HX1 (an example of the "first array") are formed as pattern P1 on the first object OB1. In addition, precision alignment marks HX2 (another example of the "first array") may be formed as pattern P1 on the first object OB1.

[0103] At least precision alignment marks HW1 (an example of a "second array") are formed as pattern P2 on the second object OB2. In addition, precision alignment marks HW2 (another example of a "second array") may be formed as pattern P1 on the second object OB2.

[0104] Pattern P1 is formed on either the front or back surface of the first object OB1. Pattern P2 is formed on the back surface of the second object OB2, which is the surface that does not face the first object OB1.

[0105] The alignment device 1 irradiates the stacked first object OB1 and second object OB2 with near-infrared light.

[0106] When a precision alignment mark HX1 is formed as pattern P1 on the first object OB1 and a precision alignment mark HW1 is formed as pattern P2 on the second object OB2, the alignment device 1 detects a signal W11 (an example of the "first signal") indicating the transmitted light of the precision alignment mark HX1 with period p1 and a signal W12 (an example of the "second signal") indicating the transmitted light of the precision alignment mark HW1 with period p1.

[0107] Specifically, multiple signals W11 are sampled for each of the X and Y directions in which the precision alignment mark HX1 extends on the first object OB1, and multiple signals W12 are sampled for each of the X and Y directions in which the precision alignment mark HW1 extends on the second object OB2.

[0108] Based on the signal intensity of signal W11 sampled in the Y direction, the signal intensity of signal W11 sampled in the X direction is added in the Y direction. Based on the signal intensity of signal W12 sampled in the Y direction, the signal intensity of signal W12 sampled in the X direction is added in the Y direction.

[0109] The signal W11 (a signal distributed on the X-axis) with the signal strength added in the Y direction, and the signal W12 (a signal distributed on the X-axis) with the signal strength added in the Y direction, are both fitted to a sine wave.

[0110] The precision alignment mark HX1 (or HX2) described above has a structure such that the signal of transmitted light, with its signal intensity added in the Y direction, approximates a sine wave in the X direction. Similarly, the precision alignment mark HW1 (or HW2) has a structure such that the signal of transmitted light, with its signal intensity added in the Y direction, approximates a sine wave in the X direction.

[0111] The alignment device 1 calculates the XY positional deviation between the first object OB1 and the second object OB2 based on signals W11 and W12, which are fitted to sine waves. Based on the XY positional deviation, the alignment device 1 adjusts the relative position of the second object OB2 with respect to the first object OB1 in the XY plane.

[0112] This processing can further improve the accuracy of the alignment. In particular, by applying a sine wave fitting method to the analysis of misalignment, high-precision alignment can be achieved even with respect to the pattern P1 on the back surface of the first object OB1. Furthermore, by detecting the transmitted light between the stacked first object OB1 and second object OB2, a high signal intensity can be obtained from the pattern P2 on the back surface of the second object OB2, making it applicable to various semiconductor processes such as exposure, imprint, and wafer bonding.

[0113] Although embodiments for carrying out the present invention have been described above using examples, the present invention is not limited in any way to these embodiments, and various modifications and substitutions can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0114] 1...Alignment device, 20...Camera, 22...Lens, 30...Fixed stage, 40...XYZθ axis movable stage, 50...Lighting device, 100...Control device, 110...Communication interface, 120...Input interface, 130...Output interface, 140...Storage unit, 150...Processing unit, 151...Acquisition unit, 152...Image processing unit, 153...Calculation unit, 154...Output control unit, OB1...First object, OB2...Second object

Claims

1. A first object on which a first array having a first periodic structure is formed, and a second object on which a second array having the first periodic structure is formed, are stacked. Irradiating the stacked first object and the second object with light, To detect a first signal which is a light signal that has passed through the first array formed on the first object, To detect the second signal, which is the light signal transmitted through the second array formed on the second object, This includes calculating the positional displacement of the stacked first and second objects based on the first and second signals, The first arrangement is formed on either the first surface of the first object or the second surface facing the first surface. The second arrangement is formed on the third surface of the second object and the fourth surface opposite the third surface, which is the surface that does not face the first object. Sampling a plurality of the first signals with respect to a first direction, which is one direction in which the first array extends on the first object, and a second direction, which is the other direction in which the first array extends on the first object. Sampling a plurality of the second signals with respect to the first direction, which is one direction in which the second array extends on the second object, and the second direction, which is the other direction in which the second array extends on the second object. Based on the signal intensity of the first signal sampled in the second direction, the signal intensity of the first signal sampled in the first direction is added in the second direction. The method further includes adding the signal intensity of the second signal sampled in the first direction to the signal intensity of the second signal sampled in the second direction, based on the signal intensity of the second signal sampled in the second direction. The first periodic structure of the first array is such that the first signal, obtained by adding the signal intensities in the second direction, approximates a sine wave in the first direction. The first periodic structure of the second array is such that the second signal, obtained by adding the signal intensities in the second direction, approximates a sine wave in the first direction. Alignment method.

2. The first periodic structure of the first array and the first periodic structure of the second array have a structure that satisfies the following formula: [Math 1] Here, y represents the signal intensity of the sampled first or second signal, x represents the sampling position of the first or second signal with respect to the first direction, λ represents the wavelength of the approximated sine wave, and a, b, c, e, d, p, M, and N are arbitrary parameters. The alignment method according to claim 1.

3. The method further includes sampling the first signal and the second signal using an image sensor in which multiple pixels are arranged in two dimensions, The sizes of the first array and the second array are larger than the size of the pixels. The alignment method according to claim 1 or 2.

4. Of the sampled first signals, the distance from the sampling position of the first signal whose signal intensity is less than the first threshold to the sampling position of the first signal whose signal intensity is greater than the first threshold and equal to or greater than the second threshold exceeds the pixel pitch, which is the distance between pixels, or Of the sampled second signals, the distance from the sampling position of the second signal whose signal intensity is less than the first threshold to the sampling position of the second signal whose signal intensity is equal to or greater than the second threshold exceeds the pixel pitch. The alignment method described in claim 3.

5. A stacked first object and second object, the first object having a first array having a first periodic structure formed thereon, and the second object having a second array having the first periodic structure formed thereon, and an irradiation unit that irradiates light onto the two objects, A detection unit that detects a first signal which is the signal of light that has passed through the first array formed in the first object, and a second signal which is the signal of light that has passed through the second array formed in the second object, The system includes a calculation unit that calculates the positional displacement of the stacked first and second objects based on the first and second signals, The first arrangement is formed on either the first surface of the first object or the second surface facing the first surface. The second arrangement is formed on the third surface of the second object and the fourth surface opposite the third surface, which is the surface that does not face the first object. The detection unit is Multiple first signals are sampled with respect to a first direction, which is one direction in which the first array extends on the first object, and a second direction, which is the other direction in which the first array extends on the first object. With respect to the first direction, which is one direction in which the second array extends on the second object, and the second direction, which is the other direction in which the second array extends on the second object, a plurality of the second signals are sampled. The calculation unit described above, Based on the signal intensity of the first signal sampled in the second direction, the signal intensity of the first signal sampled in the first direction is added in the second direction. Based on the signal intensity of the second signal sampled in the second direction, the signal intensity of the second signal sampled in the first direction is added with respect to the second direction. The first periodic structure of the first array is such that the first signal, obtained by adding the signal intensities in the second direction, approximates a sine wave in the first direction. The first periodic structure of the second array is such that the second signal, obtained by adding the signal intensities in the second direction, approximates a sine wave in the first direction. Alignment device.

6. A program to be executed by a computer, A stacked first object and a second object, wherein the first object has a first array having a first periodic structure formed on it, and the second object has a second array having the first periodic structure formed on it, and light is irradiated onto the first object and the second object. To detect a first signal which is a light signal that has passed through the first array formed on the first object, To detect the second signal, which is the light signal transmitted through the second array formed on the second object, This includes calculating the positional displacement of the stacked first and second objects based on the first and second signals, The first arrangement is formed on either the first surface of the first object or the second surface facing the first surface. The second arrangement is formed on the third surface of the second object and the fourth surface opposite the third surface, which is the surface that does not face the first object. Sampling a plurality of the first signals with respect to a first direction, which is one direction in which the first array extends on the first object, and a second direction, which is the other direction in which the first array extends on the first object. Sampling a plurality of the second signals with respect to the first direction, which is one direction in which the second array extends on the second object, and the second direction, which is the other direction in which the second array extends on the second object. Based on the signal intensity of the first signal sampled in the second direction, the signal intensity of the first signal sampled in the first direction is added in the second direction. The method further includes adding the signal intensity of the second signal sampled in the first direction to the signal intensity of the second signal sampled in the second direction, based on the signal intensity of the second signal sampled in the second direction. The first periodic structure of the first array is such that the first signal, obtained by adding the signal intensities in the second direction, approximates a sine wave in the first direction. The first periodic structure of the second array is such that the second signal, obtained by adding the signal intensities in the second direction, approximates a sine wave in the first direction. program.

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