Alignment method, manufacturing method, lithography method, alignment device, and program

Abstract

An alignment method according to an embodiment of the present invention includes: laminating a first object on which a first array body is formed and a second object on which a second array body having a first periodic structure is formed; irradiating the laminated first object and second object with light; detecting a signal of the light transmitted through each of the first array body of the first object and the second array body of the second object; and calculating positional deviation of the laminated first object and second object on the basis of a plurality of the signals. The first array body is formed on any one surface of the first object, and the second array body is formed on one of a front surface and a back surface of the second object that does not face the first object.

Description

Alignment method, manufacturing method, lithography method, alignment apparatus, and program

[0001] This application claims priority to Japanese Patent Application No. 2024-123219, filed on July 30, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, in order to achieve higher performance in semiconductor device fabrication, it has become common to place various device components, such as electrodes, wiring, optical elements, and light-receiving layers, on both sides of a wafer substrate rather than just one side. For example, one development trend in semiconductor light-receiving elements is increasing response speed. To achieve this, it is necessary to reduce the area of ​​the light-receiving layer and reduce the device capacitance. Conventionally, a front-illuminated structure has been used, in which light is directly incident on the light-receiving layer on the substrate. However, to further reduce the area of ​​the light-receiving layer, semiconductor light-receiving elements with a back-illuminated structure have been adopted, in which a lens is formed on the back side of the light-receiving layer of the substrate and light is incident through the lens surface. This requires technology to align and pattern elements on the back side of the substrate with high precision. For example, in the case of the above-mentioned light-receiving element, the light-receiving layer is first formed on the back side of the substrate, and then the lens is formed on the front side, so the optical axes of the light-receiving layer and the lens must be aligned. In other words, to achieve a smaller light-receiving layer, more precise alignment technology is required. In general, semiconductor devices are manufactured by forming elements on both sides of a substrate, such as a silicon substrate or a compound semiconductor substrate, which does not transmit visible light. Therefore, some ingenuity is required, such as using near-infrared light, which transmits through the above materials.

[0003] JP 2010-267682 A

[0004] H. Niinomi, S. Harada, T. Hayakawa, et al, “Fluorescence alignment simulation for atomic-scale position adjustment in ultraviolet nanoimprint lithography,” Journal of Vacuum Science & Technology B 35, (2022) 062602; doi: 10.1116 / 6.0002099.

[0005] Patent Document 1 (JP-A-2005-102663) provides an alignment technique using moiré fringes, which are generated by superimposing two patterns arranged at different pitches. The patterns used to generate moiré fringes in this technique must be arranged at a very small pitch, and a high-magnification lens with a high NA (numerical aperture) is required for analysis. This results in a shallow depth of focus, making it difficult to focus on the pattern on the back surface of the substrate. In other words, alignment techniques using moiré fringes can result in low alignment accuracy for patterns on the back surface of the substrate.

[0006] In Non-Patent Document 1, the signal used to detect misalignment is detected by fluorescence emission. However, the method in Non-Patent Document 1 can only be applied to substrates that transmit fluorescence wavelengths. Because the fluorescence emission signal is obtained from a third object that exists between the two media to be aligned, the method in Non-Patent Document 1 can only be applied to imprint processes.

[0007] As described above, the alignment accuracy of the conventional technology is not sufficient, and there is room for improvement in the alignment accuracy.

[0008] The present invention has been made in consideration of the above circumstances, and one of its objects is to provide an alignment method, a manufacturing method, a lithography method, an alignment apparatus, and a program that can further improve alignment accuracy.

[0009] A first example of the present invention is an alignment method that 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 light onto the stacked first object and the second object, detecting a first signal that is a signal of the light that has passed through the first array formed on the first object, detecting a second signal that is a signal of the light that has passed through the second array formed on the second object, and calculating the positional 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 opposite the first surface, and the second array is formed on the surface of the second object that does not face the first object, of the third surface of the second object or the fourth surface opposite the third surface.

[0010] A second example of the present invention is an alignment method according to the first example, wherein the first object further has a third array having a second periodic structure different from the first periodic structure, and the second object further has a fourth array having the second periodic structure, and further includes detecting a third signal which is a signal of the light that has passed through the third array formed on the first object, detecting a fourth signal which is a signal of the light that has passed through the fourth array formed on the second object, and calculating the positional misalignment of the stacked first object and second object based on the first signal, the second signal, the third signal, and the fourth signal, wherein the third array is formed on either the first surface or the second surface of the first object, and the fourth array is formed on the surface of the third surface or the fourth surface of the second object that does not face the first object.

[0011] A third example of the present invention is an alignment method according to the first or second example, which further includes adjusting the positions of the stacked first object and the second object based on the calculated positional shift, so that when the first object and the second object are stacked, the first array formed on the first object and the second array formed on the second object are formed so as not to overlap each other.

[0012] A fourth example of the present invention is an alignment method according to the first or second example, wherein the positional deviation between the first object and the second object is calculated using an optical system, the optical system including: a stage that adjusts the positions of the first object and the second object in the horizontal direction, the vertical direction, and a rotational direction on the horizontal plane; a light source that is disposed below the stage and irradiates the light; and a camera that is disposed above the stage and detects the light that has passed through the first object and the second object, wherein the light is near-infrared light.

[0013] A fifth example of the present invention is an alignment method according to the first or second example, wherein the positional deviation between the first object and the second object is calculated using an optical system, and the optical system includes a stage that adjusts the positions of the first object and the second object in the horizontal direction, the vertical direction, and a rotational direction on the horizontal plane, a light source that is disposed inside the stage and irradiates the light, and a camera that is disposed above the stage and detects the light that has passed through the first object and the second object, and the light is near-infrared light.

[0014] A sixth example of the present invention is the alignment method of the fourth example, wherein the distance between the first object and the second object that can be aligned is 2950 μm or less.

[0015] A seventh example of the present invention is the alignment method of the fourth example, wherein when the distance between the first object and the second object is 1000 μm or more, the numerical aperture of the camera's lens is 0.168 or less.

[0016] An eighth example of the present invention is an alignment method according to the first or second example, wherein the stacked first object and the second object are used in the manufacture of an optical semiconductor element, a semiconductor element, or an optical element.

[0017] A ninth example of the present invention is a method for manufacturing a laminate including a first object and a second object, the method including: stacking the first object on which a first array having a first periodic structure is formed, and the second object on which a second array having the first periodic structure is formed; irradiating light onto the stacked first object and the second object; detecting a first signal which is a signal of the light that has passed through the first array formed on the first object; detecting a second signal which is a signal of the light that has passed through the second array formed on the second object; calculating a positional shift of the stacked first object and the second object based on the first signal and the second signal; and adjusting the positions of the stacked first object and the second object based on the calculated positional shift, wherein the first array is formed on either a first surface of the first object or a second surface opposite to the first surface, and the second array is formed on one of a third surface of the second object and a fourth surface opposite to the third surface, which does not face the first object.

[0018] A tenth example of the present invention is a manufacturing method according to the ninth example, wherein the first object further has a third array having a second periodic structure different from the first periodic structure, and the second object further has a fourth array having the second periodic structure, and further includes detecting a third signal which is a signal of the light that has passed through the third array formed on the first object, detecting a fourth signal which is a signal of the light that has passed through the fourth array formed on the second object, and calculating the positional misalignment of the stacked first object and second object based on the first signal, the second signal, the third signal, and the fourth signal, wherein the third array is formed on either the first surface or the second surface of the first object, and the fourth array is formed on the surface of the third surface or the fourth surface of the second object that does not face the first object.

[0019] An eleventh example of the present invention is the manufacturing method of the ninth or tenth example, wherein the laminate is used for manufacturing any one of an optical semiconductor element, a semiconductor element, and an optical element.

[0020] A twelfth example of the present invention is a lithography method for transferring a pattern formed on one of a first object and a second object to the other, the method including: 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 object and the second object with light; detecting a first signal that is a signal of the light that has passed through the first array formed on the first object; detecting a second signal that is a signal of the light that has passed through the second array formed on the second object; calculating a positional deviation of the stacked first object and the second object based on the first signal and the second signal; a lithography method including adjusting the positions of the stacked first object and the second object based on the misalignment, wherein the first array is formed on one of the first surface of the first object and the second surface opposite the first surface, and the second array is formed on the surface of the second object that does not face the first object, of the third surface of the second object and the fourth surface opposite the third surface, and when the first array is formed as the pattern on the first object, transferring the first array formed on the first object to the second object, and when the second array is formed as the pattern on the second object, transferring the second array formed on the second object to the first object.

[0021] A thirteenth example of the present invention is the lithography method of the twelfth example, wherein a third array having a second periodic structure different from the first periodic structure is further formed on the first object, and a fourth array having the second periodic structure is further formed on the second object, and further includes detecting a third signal which is a signal of the light that has passed through the third array formed on the first object, detecting a fourth signal which is a signal of the light that has passed through the fourth array formed on the second object, and calculating a positional deviation of the stacked first object and the second object based on the first signal, the second signal, the third signal, and the fourth signal, The method further includes the steps of: when the third array is formed on one of the first surface and the second surface of the first object, and the fourth array is formed on the surface of the third surface and the fourth surface of the second object that does not face the first object, and when the first array and the third array are formed as the pattern on the first object, transferring the first array and the third array formed on the first object to the second object; and when the second array and the fourth array are formed as the pattern on the second object, transferring the second array and the fourth array formed on the second object to the first object.

[0022] A fourteenth example of the present invention is an alignment device comprising: a detection unit that detects signals of light irradiated onto and transmitted through a first object and a second object, the first object having a first array having a first periodic structure formed thereon; and a calculation unit that calculates a positional misalignment of the stacked first object and the second object based on the signals; wherein the detection unit detects a first signal that is a signal of light that has passed through the first array formed on the first object, and a second signal that is a signal of light that has passed through the second array formed on the second object; the calculation unit calculates the positional misalignment based on the first signal and the second signal; the first array is formed on either the first surface or the second surface opposite the first surface of the first object; and the second array is formed on either the third surface or the fourth surface opposite the third surface of the second object, the surface that does not face the first object.

[0023] A 15th example of the present invention is an alignment device according to the 14th example, wherein the first object further has a third array formed thereon, the third array having a second periodic structure different from the first periodic structure, and the second object further has a fourth array formed thereon, the detection unit further detects a third signal which is a signal of the light that has passed through the third array formed on the first object, and a fourth signal which is a signal of the light that has passed through the fourth array formed on the second object, and the calculation unit calculates the positional misalignment of the stacked first and second objects based on the first signal, the second signal, the third signal, and the fourth signal, and the third array is formed on either the first surface or the second surface of the first object, and the fourth array is formed on the surface of the third surface or the fourth surface of the second object that does not face the first object.

[0024] A sixteenth example of the present invention is a program to be executed by a computer, comprising: detecting a signal of light irradiated onto and transmitted through a first object and a second object that are stacked, the first object having a first array having a first periodic structure formed thereon, and a second object having a second array having the first periodic structure formed thereon; calculating a positional misalignment between the stacked first object and the second object based on the signal; detecting a first signal which is a signal of the light that has passed through the first array formed on the first object; detecting a second signal which is a signal of the light that has passed through the second array formed on the second object; and calculating the positional misalignment based on the first signal and the second signal; wherein the first array is formed on either the first surface or the second surface opposite the first surface of the first object, and the second array is formed on the surface of the second object that does not face the first object, of the third surface or the fourth surface opposite the third surface.

[0025] A 17th example of the present invention is a program in the 16th example, wherein the first object further has a third array having a second periodic structure different from the first periodic structure, and the second object further has a fourth array having the second periodic structure, and further includes detecting a third signal which is a signal of the light that has passed through the third array formed on the first object, detecting a fourth signal which is a signal of the light that has passed through the fourth array formed on the second object, and calculating the positional shift of the stacked first object and second object based on the first signal, the second signal, the third signal, and the fourth signal, wherein the third array is formed on either the first surface or the second surface of the first object, and the fourth array is formed on the surface of the third surface or the fourth surface of the second object that does not face the first object.

[0026] According to the above example, the alignment accuracy can be further improved. In particular, by applying the function fitting method to the misalignment analysis, high-precision alignment can be achieved even for patterns on the back surface of the substrate. By using a transmitted light path, high signal intensity can be obtained from the pattern on the back surface of the substrate, making it applicable to various semiconductor processes such as exposure, imprinting, and wafer bonding.

[0027] 1 is a diagram showing an example of the configuration of the alignment device 1 according to the present embodiment. FIG. 2 is a diagram showing an example of the configuration of a first object OB1 and a second object OB2 according to the present embodiment. FIG. 3 is a diagram showing an example of the configuration of a first object OB1 and a second object OB2 according to the present embodiment. FIG. 4 is a diagram showing an example of the configuration of a pattern P2 formed on a second object OB2. FIG. 5 is an enlarged view of alignment marks WA and WB. FIG. 6 is a diagram showing an example of a pattern P1 formed on a first object OB1. FIG. 7 is an enlarged view of alignment marks XA and XB. FIG. 8 is a diagram showing an example of the configuration of a control device 100 according to the present embodiment. FIG. 9 is a flowchart showing an example of a series of processing flows of the alignment device 1 according to the present embodiment. FIG. 10 is a diagram showing an example of alignment of a second object OB2 with respect to a first object OB1. FIG. 11 is a diagram showing another example of alignment of a second object OB2 with respect to a first object OB1. FIG. 12 is a diagram showing an example of an image of transmitted light of a first object OB1 and a second object OB2 aligned based on rough alignment marks MW and MX. FIG. 13 is a diagram schematically showing the state of processing from signal detection to calculation of deviation in XY position. FIG. 14 is a diagram showing an example of function fitting. FIG. 15 is a diagram showing an example of deviation in XY position. 19 is a diagram showing an example of an image obtained by capturing transmitted light through a second object OB2 (wafer). 20 is a diagram showing an example of an image obtained by capturing transmitted light through a first object OB1 (photomask). 21 is a diagram showing an example of an image obtained by capturing transmitted light through stacked first and second objects OB1 and OB2. 22 is a diagram showing examples of precision alignment marks HW1 and HW2 of a second object OB2. 23 is a diagram showing an example of a signal W12 detected from transmitted light through the precision alignment mark HW1 of FIG. 19. 24 is a diagram showing an example of a signal W22 detected from transmitted light through the precision alignment mark HW2 of FIG. 19. 25 is a diagram showing an example of experimental results in an example and a comparative example. 26 is a diagram showing an example of the configuration of a first object OB1 of an example. 27 is a diagram showing an example of the configuration of a second object OB2 of an example. 28 is a diagram for explaining an experimental method of an example. 29 is a diagram for explaining an experimental method of an example. 29 is a diagram for explaining an experimental method of an example. 29 is a diagram showing the relationship between the object-side NA of a lens 22 and a focusable distance. 29 is a diagram showing experimental results of Example 1. 1 is a diagram showing the experimental results of Example 1. FIG. 2 is a diagram showing the experimental results of Example 1.FIG. 1 is a diagram showing the experimental results of Example 2. FIG. 1 is a diagram showing the experimental results of Example 2. FIG. 2 is a diagram showing the experimental results of Example 2. FIG. 3 is a diagram showing the experimental results of Comparative Example 1. FIG. 4 is a diagram showing the experimental results of Comparative Example 1. FIG. 5 is a diagram showing the experimental results of Example 5. FIG. 6 is a diagram showing the experimental results of Example 6. FIG. 7 is a diagram showing the experimental results of Example 7. FIG. 8 is a diagram showing the experimental results of Example 7. FIG. 9 is a diagram showing the experimental results of Example 9. FIG. 10 is a diagram showing the experimental results of Example 10. FIG. 11 is a diagram showing the experimental results of Example 10. FIG. 12 is a diagram showing the experimental results of Example 11. FIG. 13 is a diagram showing the experimental results of Example 12. FIG. 14 is a diagram showing the experimental results of Example 13. FIG. 15 is a diagram showing the experimental results of Example 14. FIG. 16 is a diagram showing the experimental results of Example 16. FIG. 17 is a diagram showing the experimental results of Example 17. FIG. 18 is a diagram showing the experimental results of Example 18. FIG. 19 is a diagram showing the experimental results of Example 19. FIG. 20 is a diagram showing the experimental results of Example 20. FIG. 21 is a diagram showing the experimental results of Example 20. FIG. 22 is a diagram showing the experimental results of Example 20. FIG. 23 is a diagram showing the experimental results of Example 20. FIG. 10 is a diagram showing the experimental results of Example 8. FIG. 11 is a diagram showing the experimental results of Example 8. FIG. 12 is a diagram showing the experimental results of Example 9. FIG. 13 is a diagram showing the experimental results of Example 9. FIG. 14 is a diagram showing the experimental results of Example 9. FIG. 15 is a diagram showing the experimental results of Comparative Example 4. FIG. 16 is a diagram showing the experimental results of Comparative Example 4. FIG. 17 is a diagram showing the experimental results of Comparative Example 5. FIG. 18 is a diagram showing the experimental results of Comparative Example 5.

[0028] Hereinafter, with reference to the drawings, embodiments of an alignment method, a manufacturing method, a lithography method, an alignment apparatus, and a program according to the present invention will be described.

[0029] [Configuration Example of Alignment Apparatus (Laminate Manufacturing Apparatus)] Fig. 1 is a diagram showing an example of the configuration of an alignment apparatus 1 according to this embodiment. The alignment apparatus 1 is also a laminate manufacturing apparatus 1. As shown in Fig. 1, the alignment apparatus 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. The camera 20, the fixed stage 30, the XYZθ-axis movable stage 40, and the illumination device 50 are an example of an "optical system."

[0030] In the figure, X represents one direction (axis) forming a horizontal plane, Y represents another direction (axis) forming the horizontal plane, and Z represents a vertical direction (vertical axis) perpendicular to the horizontal plane. In other words, X represents the width direction, Y represents the depth direction, and Z represents the height direction.

[0031] The alignment device 1 stacks a first object OB1 and a second object OB2, irradiates light from below or above the first object OB1 and the second object OB2, detects the transmitted light that passes through the first object OB1 and the second object OB2 as an electrical signal, calculates the positional deviation 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 the positional deviation.

[0032] 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 a compound semiconductor. A stack of the first object OB1 and the second object OB2 may be used to manufacture any of an optical semiconductor element, a semiconductor element, and an optical element.

[0033] The alignment device 1 typically adjusts the position of the second object OB2, which is a substrate, relative to the first object OB1, such as a photomask or a mold, when stacking the first object OB1 and the second object OB2. In other words, of the first object OB1 and the second object OB2, one of the second objects OB2, the second object OB2, is the target of alignment. Patterns are formed on the first object OB1 and the second object OB2 to perform alignment during stacking. Details of each pattern will be described later.

[0034] The camera 20 is disposed, for example, above the fixed stage 30, the XYZθ-axis movable stage 40, and the lighting device 50. The camera 20 detects transmitted light, which is light irradiated from the lighting device 50 and transmitted through the first object OB1 and the second object OB2, via the lens 22. The bit depth of the camera 20 may be 8 bits or more, and preferably 12 bits or more. The NA (numerical aperture) of the lens 22, i.e., the observation magnification of the camera 20, may be a low magnification such as 0.5x, 1.0x, or 2.0x.

[0035] As will be explained in the examples below, it is necessary to accurately detect an amplitude ratio of 0.1. Therefore, it is preferable that the camera 20 has 32 or more gradations, i.e., 5 or more bits. In terms of the cost of the camera 20 and the processing power of the system, it is more preferable that the camera 20 has a resolution of about 12 or 16 bits.

[0036] The fixed stage 30 holds a first object OB1 under the control of the control device 100, for example, and stacks the first object OB1 on a second object OB2 placed on an XYZθ-axis movable stage 40.

[0037] A second object OB2 is placed on the XYZθ-axis movable stage 40. The XYZθ-axis movable stage 40 moves the placed second object OB2 in the horizontal direction (XY direction), the vertical direction (Z direction), and the rotational direction (θ direction) on the horizontal plane, for example, in accordance with the control of the control device 100.

[0038] The illumination device 50 is disposed, for example, below the camera 20, the fixed stage 30, and the XYZθ-axis movable stage 40. The illumination device 50 may be disposed 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 irradiating the imaging area of ​​the camera 20. Specifically, the illumination device 50 may irradiate near-infrared light with a wavelength of approximately 1050 nm. When the camera 20 is disposed below the fixed stage 30, the XYZθ-axis movable stage 40, and the illumination device 50, the illumination device 50 may be disposed above them. In this case, the illumination device 50 irradiates the stacked first object OB1 and second object OB2 with light from above.

[0039] 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.

[0040] 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 further include a coating device 60, an ultraviolet irradiation device 70, etc.

[0041] The coating device 60 applies, for example, an ultraviolet curable resin containing a fluorescent dye (ultraviolet curable visible fluorescent liquid) between the first object OB1 and the second object OB2 under the control of the control device 100.

[0042] The ultraviolet irradiation device 70 may, for example, irradiate ultraviolet rays onto the first object OB1 and the second object OB2 to which the ultraviolet curable resin has been applied, thereby curing the ultraviolet curable resin, in accordance with the control of the control device 100. In this way, the stacked first object OB1 and the second object OB2 are bonded together by the ultraviolet curable resin, and a stack including the first object OB1 and the second object OB2 is manufactured.

[0043] [Configuration of the First Object and the Second Object (Stack)] Next, the configuration of the first object OB1 and the second object OB2 will be described. Figures 2 and 3 are diagrams showing an example of the configuration of the first object OB1 and the second object OB2 according to this embodiment.

[0044] In this embodiment, a pattern P1 is formed on the first object OB1, and a pattern P2 is formed on the second object OB2.

[0045] For example, as shown in Figure 2, pattern P1 is formed on the back surface of first object OB1, which is the surface facing second object OB2, out of the front and back surfaces. Pattern P1 may be formed, for example, by removing a portion of a chromium film or the like formed on the back surface by etching or the like. The front surface of first object OB1 is an example of the "first surface," and the back surface of first object OB1 is an example of the "second surface."

[0046] On the other hand, pattern P2 is formed on the rear surface of second object OB2, which is the surface that does not face first object OB1, out of the front and rear surfaces. Pattern P2 may be formed, for example, by removing a portion of a metal light-shielding film formed on the rear surface by etching or the like. The front surface of second object OB2 is an example of a "third surface," and the rear surface of second object OB2 is an example of a "fourth surface."

[0047] 3, the pattern P1 may be formed on the front side of the first object OB1, which is the surface that does not face the second object OB2, out of the front and back sides of the first object OB1. Even when the pattern P1 is formed on the front side of the first object OB1, the pattern P2 is formed on the back side of the second object OB2.

[0048] The following describes the pattern P2 formed on the second object OB2 before the pattern P1 formed on the first object OB1. Fig. 4 is a diagram showing an example of the pattern P2 formed on the second object OB2.

[0049] The pattern P2 includes alignment marks WA and WB. The alignment marks WA and WB are formed on the outside (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, 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.

[0050] 5 is an enlarged view of the alignment marks WA and WB. The alignment marks WA and WB include a coarse alignment mark MW and a fine alignment mark HW1.

[0051] The rough alignment marks MW are marks for roughly aligning 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 the rough alignment marks MW are formed at positions spaced apart from each other on a diagonal line.

[0052] The precision alignment mark HW1 is a mark for precisely aligning the positions of the first object OB1 and the second object OB2.

[0053] The precision alignment mark HW1 may have a periodic structure in which a large number of bars are arranged at intervals of a period p1. The period p1 may be, for example, about 45.0 μm. The precision alignment mark HW1 is an example of a "first array."

[0054] The period p1 of the precision alignment mark HW1 may be five times or more the pixel size of the camera 20, and more preferably nine times or more.

[0055] Next, the pattern P1 formed on the first object OB1 will be described. Fig. 6 is a diagram showing an example of the pattern P1 formed on the first object OB1.

[0056] The pattern P1 includes alignment marks XA and XB. The alignment marks XA and XB are formed on the outside (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, 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.

[0057] 7 is an enlarged view of the alignment marks XA and XB. The alignment marks XA and XB include a rough alignment mark MX and a precision alignment mark HX1.

[0058] The coarse alignment mark MX is a mark for roughly aligning the positions of the first object OB1 and the second object OB2, similar to the above-mentioned coarse alignment mark MW.

[0059] The coarse alignment marks MX may be, for example, square marks, and similarly to the coarse alignment marks MW, two of them are formed at positions spaced apart from each other on a diagonal line.

[0060] The precision alignment mark HX1 is a mark for precisely aligning the positions of the first object OB1 and the second object OB2, similar to the precision alignment mark HW1 described above.

[0061] Like the precision alignment mark HW1, the precision alignment mark HX1 may have a periodic structure in which a large number of bars are arranged at intervals of a period p1. The precision alignment mark HX1 is an example of a "second array."

[0062] The period p1 of the precision alignment marks HX1 may be at least five times the pixel size of the camera 20, and is more preferably at least nine times the pixel size.

[0063] When the first object OB1 and the second object OB2 are stacked, the precision alignment mark HX1 formed as a pattern P1 on the first object OB1 and the precision alignment mark HW1 formed as a pattern P2 on the second object OB2 are formed so as not to overlap each other when viewed from above or below (i.e., in the Z direction).

[0064] The patterns P1 and P2 may be formed using, for example, photolithography or electron beam lithography, which transfers a pattern formed on one side to the other side.

[0065] Specifically, if precision alignment mark HX1 is first formed on first object OB1 as part of pattern P1, then precision alignment mark HX1 may be transferred to second object OB2 as precision alignment mark HW1. If precision alignment mark HW1 is first formed on second object OB2 as part of pattern P2, then precision alignment mark HW1 may be transferred to first object OB1 as precision alignment mark HX1.

[0066] [Configuration of Control Device] Next, a description will be given of the configuration of the control device 100. Fig. 8 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.

[0067] The communication interface 110 includes, for example, a network interface card (NIC) 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 local area network (LAN) or a wide area network (WAN). Examples of the external devices include the camera 20, the fixed stage 30, the XYZθ-axis movable stage 40, the lighting device 50, the coating device 60, and the ultraviolet irradiation device 70.

[0068] The input interface 120 accepts various input operations from the user, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing unit 150. For example, the input interface 120 includes a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch panel, etc. The input interface 120 may also be a voice user interface that accepts voice input including a microphone, etc.

[0069] The output interface 130 includes, for example, a display and a speaker. The display displays images generated by the processing unit 150, a GUI (Graphical User Interface) for receiving various input operations from the user, and the like. For example, the display is an LCD (Liquid Crystal Display), an organic EL (Electro Luminescence) display, or the like. The speaker outputs information input from the processing unit 150 as sound.

[0070] The storage unit 140 is realized by, for example, a hard disk drive (HDD), a flash memory, an electrically erasable programmable read-only memory (EEPROM), a read-only memory (ROM), a random access memory (RAM), etc. The storage unit 140 stores various programs such as firmware and application programs.

[0071] 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 image processing unit 152 is an example of a "detection unit."

[0072] The components of the processing unit 150 are realized by a processor such as a central processing unit (CPU) or a graphics processing unit (GPU) executing a program stored in the storage unit 140. Some or all of the components of the processing unit 150 may be realized by hardware such as a large-scale integration (LSI), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a system-on-chip (SOC), or may be realized by a combination of software and hardware.

[0073] [Processing Flow of Alignment Apparatus] A series of processing flows of the alignment apparatus 1 will be described below with reference to a flowchart. Fig. 9 is a flowchart showing an example of a series of processing flows of the alignment apparatus 1 according to this embodiment. The processing of this flowchart may be repeated at a predetermined interval, for example.

[0074] First, the output control unit 154 of the control device 100 controls the camera 20, the fixed stage 30 that holds the first object OB1 on which the pattern P1 is formed, the XYZθ-axis movable stage 40 on which the second object OB2 on which the pattern P2 is formed is placed, and the lighting device 50 to align the first object OB1 and the second object OB2 (step S100). The process (alignment) of S100 may be performed by a user such as a manufacturer or an operator, instead of by the control device 100.

[0075] Specifically, the output control unit 154 irradiates light from the illumination device 50 toward the stacked first object OB1 and second object OB2. The light irradiated from the illumination device 50 passes through the second object OB2 placed on the XYZθ-axis movable stage 40, and further passes through the first object OB1 held by the fixed stage 30, and is received by the camera 20 via the lens 22. In other words, the camera 20 captures an image of the transmitted light.

[0076] The acquisition unit 151 of the control device 100 acquires an image of transmitted light from the camera 20 .

[0077] Next, the image processing unit 152 detects two coarse alignment marks MX and two coarse alignment marks MW from the image of transmitted light (step S102).

[0078] For example, the image processing unit 152 may detect two rough alignment marks MX from only one of the alignment marks XA and XB formed as pattern P1 on the first object OB1, or may detect two rough alignment marks MX from both XA and XB.

[0079] Similarly, for example, the image processing unit 152 may detect two rough alignment marks MW from only one of the alignment marks WA and WB formed as pattern P2 on the second object OB2, or may detect two rough alignment marks MW from both WA and WB.

[0080] Next, the image processing unit 152 detects the center of gravity GX based on the two rough alignment marks MX, and detects the center of gravity GW based on the two rough alignment marks MW (step S104).

[0081] Next, the calculation unit 153 calculates the XYθ movement amount of the second object OB2 relative to the first object OB1 based on the two rough alignment marks MX, the two rough alignment marks MW, the center of gravity GX, and the center of gravity GW (step S106). The XYθ movement amount represents the movement amount (distance) in the XY plane (horizontal plane) and the movement amount in the θ direction (rotational direction) on the XY plane (i.e., the rotation angle).

[0082] Next, the output control unit 154 adjusts the relative position of the second object OB2 in the XY plane with respect to the first object OB1 by controlling the XYZθ-axis movable stage 40 based on the XYθ movement amount (step S108). That is, the second object OB2 is roughly aligned with the first object OB1 based on the two rough alignment marks MX and the two rough alignment marks MW. The processing of S108 may be performed by the user instead of by the control device 100.

[0083] 10 is a diagram showing an example of alignment of a second object OB2 with a first object OB1. As shown in the figure, for example, of alignment marks WA and WB patterned on the second object OB2, two rough alignment marks MW are detected only from WA on the left side of the figure. In this case, the center of gravity GW is detected based on the two rough alignment marks MW detected from the alignment mark WA.

[0084] Furthermore, the center of gravity GX is detected based on two rough alignment marks MX detected from alignment marks XA and XB patterned on the first object OB1, the position of which corresponds to alignment mark WA.

[0085] Then, the XYθ movement amount is calculated based on the two rough alignment marks MW and the center of gravity GW derived from the alignment mark WA on the left side of the drawing, and the two rough alignment marks MX and the center of gravity GX derived from the alignment mark WX on the left side of the drawing. In this way, alignment may be performed using only one of the alignment marks.

[0086] 11 is a diagram showing another example of alignment of a second object OB2 with respect to a first object OB1. In the above-described FIG. 10, alignment is performed using only one of the alignment marks, but this is not limiting. For example, as shown in FIG. 10, alignment may be performed using both alignment marks.

[0087] Returning to the description of the flowchart, next, the image processing unit 152 detects the precision alignment marks HX1 and HW1 from the image of the transmitted light of the first object OB1 and the second object OB2 aligned based on the rough alignment marks MW and MX (step S110).

[0088] 12 is a diagram showing an example of an image of transmitted light of the first object OB1 and the second object OB2 aligned based on the coarse alignment marks MW and MX. As described above, the fine alignment marks HX1 and HW1 are patterned in advance so as not to overlap with each other, and therefore are detected without overlapping with each other in the image of transmitted light.

[0089] Returning to the description of the flowchart, the image processing unit 152 then detects a signal representing the transmitted light through the precision alignment mark HX1 having the period p1 (hereinafter referred to as signal W11) and a signal representing the transmitted light through the precision alignment mark HW1 having the period p1 (hereinafter referred to as signal W12) (step S112).

[0090] The signal W11 is an example of a "first signal," and the signal W12 is an example of a "second signal."

[0091] Each signal may be generated, for example, by plotting the signal intensity (received light intensity) of each pixel in the X direction. That is, each signal may be a discrete signal that indicates the signal intensity in the X direction.

[0092] Next, the calculation unit 153 fits each of the signals W11 and W12 to a predetermined function (step S114).

[0093] Next, the calculation unit 153 calculates the deviation of the XY positions of the first object OB1 and the second object OB2 based on the signals W11 and W12 fitted to the function (step S116). The deviation of the XY positions is the deviation (distance) of the positions of the objects on the XY plane.

[0094] Next, the output control unit 154 adjusts the relative position of the second object OB2 in the XY plane with respect to the first object OB1 by controlling the XYZθ-axis movable stage 40 based on the deviation of the XY positions (step S118). In other words, the second object OB2 is precisely aligned with respect to the first object OB1 based on the precision alignment marks HX1 and HW1. The processing of S118 may be performed by the user instead of by the control device 100. This completes the series of processing steps in the flowchart.

[0095] If precision alignment marks HX1 and HW1 are formed on the first object OB1 and the second object OB2, respectively, it is possible to perform the alignment in step S118, but if the processing of S118 is performed by the control device 100, the presence of precision alignment marks HW2 and HX2 may make it easier to recognize the direction of displacement. For this reason, precision alignment marks HW2 and HX2 may be formed on the first object OB1 and the second object OB2, respectively.

[0096] The precision alignment mark HW2 may have a periodic structure in which a large number of bars are arranged at intervals of a period p2. The period p2 may be any period different from the period p1, and may be, for example, about 46.0 μm. The precision alignment mark HW2 is an example of a "third array."

[0097] Like the precision alignment mark HW2, the precision alignment mark HX2 may have a periodic structure in which a large number of bars are arranged at intervals of a period p2. The precision alignment mark HX2 is an example of a "fourth array."

[0098] 13 is a diagram showing a schematic diagram of the process from signal detection to calculation of XY position deviation. A signal W11 is detected from light transmitted through the precision alignment mark HX1 with period p1, and a signal W12 is detected from light transmitted through the precision alignment mark HW1 with period p1. The signals W11 and W12 are each fitted to a function. The XY position deviation is then calculated from the signals W11 and W12 fitted to the function.

[0099] 14 is a diagram showing an example of function fitting. As shown in the figure, the signals W11 and W12, which are discrete signals of signal strength, may be fitted to, for example, a sine function or a cosine function.

[0100] 15 is a diagram showing an example of the deviation in XY position. For example, the calculation unit 153 calculates the deviation between the signals W11 and W12 in each period (e.g., the distance between the peaks). 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 the signals W11 and W12. The calculation unit 153 then calculates the deviation between the signals W11 and W12 as the deviation in the XY position between the first object OB1 and the second object OB2.

[0101] The calculation unit 153 may calculate the deviation between the signals W21 and W22 instead of calculating the deviation between the signals W11 and W12, and use this as the deviation in the XY positions of the first object OB1 and the second object OB2.

[0102] The signal W21 is a signal representing the transmitted light through the precision alignment mark HX2 having the period p2, and the signal W22 is a signal representing the transmitted light through the precision alignment mark HW2 having the period p2.

[0103] Although the precision alignment marks HX1, HX2, HW1, and HW2 have been described as having a structure in which a number of bars are arranged in the X direction at intervals of a period p1 or p2, this is not limiting. For example, the precision alignment marks HX1, HX2, HW1, and HW2 may have a structure in which a number of bars are arranged in the Y direction at intervals of a period p1 or p2. In this case, not only the deviation in the X position between the first object OB1 and the second object OB2 but also the deviation in the Y position can be calculated. As a result, the first object OB1 and the second object OB2 can be precisely aligned on the X-Y plane.

[0104] According to the embodiment described above, the alignment apparatus 1 stacks a first object OB1 (for example, a photomask) and a second object OB2 (for example, a wafer).

[0105] At least a precision alignment mark HX1 (an example of a "first array") is formed as a pattern P1 on the first object OB1. In addition, a precision alignment mark HX2 (an example of a "third array") may be formed as a pattern P1 on the first object OB1.

[0106] At least a precision alignment mark HW1 (an example of a "second array") is formed as a pattern P2 on the second object OB2. In addition, a precision alignment mark HW2 (an example of a "fourth array") may be formed as a pattern P1 on the second object OB2.

[0107] The pattern P1 is formed on either the front or back surface of the first object OB1, and the 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.

[0108] The alignment device 1 irradiates near-infrared light onto the stacked first object OB1 and second object OB2.

[0109] When a precision alignment mark HX1 is formed as a pattern P1 on a first object OB1 and a precision alignment mark HW1 is formed as a pattern P2 on a second object OB2, the alignment device 1 detects a signal W11 (an example of a "first signal") indicating the transmitted light through the precision alignment mark HX1 with a period p1 and a signal W12 (an example of a "second signal") indicating the transmitted light through the precision alignment mark HW1 with a period p1.

[0110] When a precision alignment mark HX2 is formed as a pattern P1 on a first object OB1 and a precision alignment mark HW2 is formed as a pattern P2 on a second object OB2, the alignment device 1 detects a signal W21 (an example of a "third signal") indicating the transmitted light through the precision alignment mark HX2 with a period p2, and a signal W22 (an example of a "fourth signal") indicating the transmitted light through the precision alignment mark HW2 with a period p2.

[0111] The alignment device 1 calculates the deviation in the XY positions of the first object OB1 and the second object OB2, and adjusts the relative position of the second object OB2 in the XY plane with respect to the first object OB1 based on the deviation in the XY positions.

[0112] This type of processing can further improve alignment accuracy. In particular, applying a function fitting method to misalignment analysis enables highly accurate alignment of the pattern P1 on the back surface of the first object OB1. By detecting the light transmitted through 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, which can be applied to various semiconductor processes such as exposure, imprinting, and wafer bonding.

[0113] The above describes the form for carrying out the present invention using an embodiment, but the present invention is not limited to such an embodiment, and various modifications and substitutions can be made within the scope that does not deviate from the gist of the present invention.

[0114] The following describes the examples. The camera 20 used was an ABA-013VIR (Aval Data). The lens 22 used was an MP-1M-65-NIR (Optoart). The lighting device 50 used a TH2-100X100IR105 (CSS). The near-infrared light used had a wavelength of 1050 nm. A glass mask was used for the first object OB1, and a pattern P1 was formed by etching a 100 nm chromium film. The second object OB2 used a 280 μm silicon wafer with polished finishes on both sides. A metal light-shielding film was formed as pattern P2 on the back surface of the second object OB2.

[0115] Fig. 16 is a diagram showing an example of an image obtained by capturing light transmitted through a second object OB2 (wafer). Fig. 17 is a diagram showing an example of an image obtained by capturing light transmitted through a first object OB1 (photomask). In order to calculate deviations in not only the X position but also the Y position, precision alignment marks HX1, HX2, HW1, and HW2 are patterned in the illustrated image not only in the X direction but also in the Y direction.

[0116] 18 is a diagram showing an example of an image obtained by capturing light transmitted through a first object OB1 and a second object OB2 that are stacked together. As shown in the figure, the precision alignment marks are detected without overlapping.

[0117] FIG. 19 is a diagram showing an example of precision alignment marks HW1 and HW2 of the second object OB2. The period p1 of the precision alignment mark HW1 in FIG. 19 is 58.56 [μm]. FIG. 20 is a diagram showing an example of a signal W12 detected from light transmitted through the precision alignment mark HW1 in FIG. 19. FIG. 21 is a diagram showing an example of a signal W22 detected from light transmitted through the precision alignment mark HW2 in FIG. 19. The amplitude of the signal W12 was 42.266, the phase shift was −3.426 [px], and the period was 11.712 [px]. The amplitude of the signal W22 was 45.339, the phase shift was 1.339 [px], and the period was 12.108 [px].

[0118] 22 is a diagram showing an example of experimental results in Examples and Comparative Examples. Examples 1-9 are methods that employ a transmission optical system and are methods that succeed in focusing various precision alignment marks. On the other hand, Comparative Example 1-4 is a method that employs a transmission optical system but fails to focus various precision alignment marks. Comparative Example 5 is a method that employs a reflection optical system and is a method that fails to focus various precision alignment marks.

[0119] Details of Examples 1-9 and Comparative Examples 1-5 will be described later, but in order to focus on both the first object OB1 and the second object OB2, the NA (numerical aperture) on the object side of lens 22 needs to be 0.168 or less.

[0120] The NA can be calculated from the following formula: M represents the magnification, and can be calculated by dividing the size of the mark on the image by the size of the actual mark. F represents the F-number of the lens 22.

[0121] NA=M / {2(1+M)F}

[0122] A common condition for the configurations of Examples 1-9 and Comparative Examples 1-5 is that a sensor such as Si-CMOS, InGaAs, or PbS may be used for the camera 20. In particular, since a high signal strength for near-infrared light is preferable, InGaAs or PbS is preferable. In Examples 1-9 and Comparative Examples 1-5, an ABA-013VIR (Aval Data) was used as the camera 20.

[0123] The illumination device 50 may be a surface light source, a spot light source, a fiber light source, a VCSEL (Vertical Cavity Surface Emitting Laser), or the like. Since uniform illuminance within the plane is particularly desirable, it is preferable to employ a surface light source or a VCSEL for the illumination device 50. The wider the range over which the illuminance is uniform within the plane, the wider the pattern analysis range can be, and the greater the number of mark periods can be. As a result, the detection accuracy of the amount of phase shift can be improved.

[0124] The light emitted from the lighting device 50 may be configured to be incident on the camera 20 from the front. This allows the distance between the lighting device 50 and the camera 20 to be shortened, and the amount of light received by the camera 20 to be increased. As a result, the signal strength can be increased and the amplitude of the fitting function can be increased, thereby improving the accuracy of detecting the period and further improving the accuracy of detecting the amount of positional displacement. In Example 1-9 and Comparative Example 1-5, near-infrared light with a wavelength of 1050 [nm] was used as the light emitted from the lighting device 50.

[0125] 23 is a diagram showing an example of the configuration of the first object OB1 in the examples. In Examples 1-9 and Comparative Examples 1-5, a colorless photomask was used as the first object OB1. The material was glass, and the outer diameter was 127 mm × 127 mm, and the thickness was 2.3 mm. A 100 nm thick chromium film was formed on the rear surface of the glass, and a reflective (light-blocking) pattern P1 was formed by etching a portion of the chromium film.

[0126] FIG. 24 is a diagram showing an example of the configuration of the second object OB2 in the examples. In Examples 1-9 and Comparative Examples 1-5, a double-side polished wafer was used as the second object OB2. The material was silicon, and the outer diameter was a circle with a diameter of 51.2 mm and a thickness of 280 μm. A gold (Au) film was formed on the backside of the wafer, and a titanium (Ti) film was formed between the wafer and the gold film to increase adhesion between them. The titanium film was 10 nm thick, and the gold film was 200 nm thick. A reflective (light-blocking) pattern P2 was formed by etching portions of the titanium film and the gold film.

[0127] 25 to 29 are diagrams illustrating the experimental method of the example. As shown in FIG. 25, experiments were conducted while changing the size of the gap (distance) formed between the first object OB1 and the second object OB2. Reference numeral 24 denotes a close-up ring (also called a close-up tube or extension tube) connected to the end of the lens 22 that is closer to the camera 20. The close-up ring 24 is used to adjust the magnification of the camera 20, and the length of this close-up ring 24 was also changed during the experiments.

[0128] The lens 22 may be, for example, M5018-VSW (manufactured by Computer) or OS-TCM1.0-H1.1-CEI (manufactured by Sigma Koki).

[0129] 26 , first, when the gap between the first object OB1 and the second object OB2 is 0 μm, the control device 100 irradiates light toward the stacked first object OB1 and the second object OB2 and captures images of the first object OB1 and the second object OB2. Hereinafter, the state in which the gap is 0 μm will be referred to as the initial state. In the initial state, the control device 100 focuses the camera 20 on the precision alignment mark HX2 formed as the pattern P1 on the first object OB1 and the precision alignment mark HW2 formed as the pattern P2 on the second object OB2.

[0130] Next, the control device 100 changes the gap from the initial state while irradiating light toward the stacked first object OB1 and second object OB2, and captures images of the first object OB1 and the second object OB2, thereby acquiring new images of the first object OB1 and the second object OB2.

[0131] Next, the control device 100 calculates an analysis range R ＨＸ２ A signal W21 indicating transmitted light through the precision alignment mark HX2 of the period p2 is detected from a part of the precision alignment mark HX2 included in the analysis range R ＨＷ２ A signal W22 indicating transmitted light through the precision alignment mark HW2 of the period p2 is detected from a part of the precision alignment mark HW2 included in the period p2.

[0132] FIG. 27 shows the analysis range R ＨＸ２ and analysis range R ＨＷ２ As shown in the figure, the precision alignment marks HX2 and HW2 are formed by alternating white areas (light transmitting areas) and black areas (light reflecting areas) in a cyclical pattern. A combination of one white area and one black area constitutes one period (T=1). In the embodiment, the analysis range R ＨＸ２ and analysis range R ＨＷ２ is set to include 14 periods (T=14).

[0133] Next, the control device 100 fits each of the signals W21 and W22 to a predetermined function to calculate the amplitude, phase, and period.

[0134] 28 is a diagram showing an example of the analysis results of the signal W22 detected from the light transmitted through the precision alignment mark HW2. The vertical axis represents signal intensity, and the horizontal axis represents pixels [px]. In the example shown, the amplitude of the signal W22 is 33.254, the phase is 3.135 [px], and the period is 12.465 [px].

[0135] 29 is a diagram showing an example of the analysis results of the signal W21 detected from the light transmitted through the precision alignment mark HX2. In the example shown, the amplitude of the signal W21 is 30.337, the phase is 3.628 [px], and the period is 12.462 [px].

[0136] The control device 100 further calculates the amplitude ratio. For example, in the examples of Figures 28 and 29, the amplitude ratio = 33.254 ÷ 30.337 = 1.10 (rounded to two decimal places). The amplitude ratio is not involved in determining whether or not focusing has been achieved, but the amplitude ratio tends to decrease as the gap increases.

[0137] The control device 100 further calculates the period difference. For example, in the examples of Figures 28 and 29, the period difference = 12.465 [px] - 12.462 [px] = 0.003 [px]. In this embodiment, if the period difference is 0.05 [px] or more, it is considered that focusing has failed, and if the period difference is less than 0.05 [px], it is considered that focusing has succeeded.

[0138] The control device 100 may further calculate the amount of misalignment in the X direction or the Y direction. For example, in the examples of FIGS. 28 and 29, the absolute value of the amount of phase shift is |3.135 [px] - 3.628 [px]| = 0.493 [px]. The control device 100 calculates the amount of misalignment by multiplying the absolute value of the amount of phase shift by the pixel size. For example, if the pixel size is 5.0 [μm / px], the amount of misalignment is calculated as 5.0 [μm / px] × 0.493 [px] = 2.465 [μm].

[0139] The larger the gap, the smaller the amplitude of the signal W22 detected from the light transmitted through the precision alignment mark HW2 of the second object OB2, which is a wafer. As a result, a shift occurs in the period of the fitting function, and the detection accuracy of the amount of phase change decreases. Therefore, an appropriate NA (object-side NA) of the lens 22 is required depending on the size of the gap.

[0140] Fig. 30 is a diagram showing the relationship between the object-side NA of the lens 22 and the focusable distance. The vertical axis of the graph in Fig. 30 represents the maximum gap amount [µm], and the horizontal axis represents the object-side NA.

[0141] The larger the gap between the first object OB1 and the second object OB2, the wider the range of applications. For example, the larger the gap, the thicker each object can be, or the number of objects can be increased. Therefore, the graph in Figure 30 plots the results of examples with relatively large gaps from Examples 1-9, which are successful focusing examples shown in Figure 22.

[0142] Specifically, among Examples 1 and 2, which all share the object-side NA of 0.094, the results of Example 2, which has the larger gap (NA = 0.094, gap = 2800 μm), are plotted. Similarly, among Examples 3 to 5, which all share the object-side NA of 0.140, the results of Example 5, which has the largest gap (NA = 0.140, gap = 2950 μm), are plotted. Among Examples 6 and 7, which all share the object-side NA of 0.168, the results of Example 7, which has the larger gap (NA = 0.168, gap = 1750 μm), are plotted. And among Examples 8 and 9, which all share the object-side NA of 0.650, the results of Example 9, which has the larger gap (NA = 0.650, gap = 700 μm), are plotted.

[0143] For example, when considering practical uses of the stacked first object OB1 and second object OB2, it is preferable that the gap be at least 1000 μm or more. To satisfy this requirement, as described above, it is understood that the NA of the lens 22 should be at least 0.168 or less.

[0144] The gap between the first object OB1 and the second object OB2 that can be aligned may be 2950 μm or less.

[0145] The experimental results of Examples 1-9 and Comparative Examples 1-5 will be described below. Figures 31 to 33 are diagrams showing the experimental results of Example 1. In Example 1, the type of lens 22 was M5018-VSW (manufactured by Computar), the length of the close-up ring 24 was 25 mm, the F-number was 1.8, the magnification was 0.51, the object-side NA was 0.094, the optical system was transmissive, and the gap was 450 μm.

[0146] Under these conditions, the experiment of Example 1 was performed, and the results were that the amplitude of signal W22 was 24.178, the phase was -0.799 [px], and the period was 6.185 [px]. The amplitude of signal W21 was 27.027, the phase was -0.719 [px], and the period was 6.184 [px]. The amplitude ratio was 0.89, and the period difference per pixel was 0.001 [px]. Example 1 was successful in focusing various precision alignment marks.

[0147] 34 to 36 are diagrams showing the experimental results of Example 2. In Example 2, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 25 mm, the F-number was 1.8, the magnification was 0.51, the object-side NA was 0.094, the optical system was transmissive, and the gap was 2800 μm.

[0148] Under these conditions, the experiment of Example 2 was performed, and the results were that the amplitude of signal W22 was 2.528, the phase was 0.286 [px], and the period was 6.162 [px]. The amplitude of signal W21 was 26.479, the phase was -0.470 [px], and the period was 6.187 [px]. The amplitude ratio was 0.10, and the period difference per pixel was 0.025 [px]. Example 2 was successful in focusing various precision alignment marks.

[0149] 37 to 39 are diagrams showing the experimental results of Comparative Example 1. In Comparative Example 1, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 25 mm, the F-number was 1.8, the magnification was 0.51, the object-side NA was 0.094, the optical system was transmissive, and the gap was 2850 μm.

[0150] Under these conditions, the experiment for Comparative Example 1 was performed, and the results were that the amplitude of signal W22 was 2.383, the phase was 0.500 [px], and the period was 6.129 [px]. The amplitude of signal W21 was 26.479, the phase was -0.470 [px], and the period was 6.187 [px]. The amplitude ratio was 0.09, and the period difference per pixel was 0.058 [px]. Comparative Example 1 failed to focus various precision alignment marks.

[0151] 40 to 42 are diagrams showing the experimental results of Example 3. In Example 3, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 50 mm, the F-number was 1.8, the magnification was 1.01, the object-side NA was 0.140, the optical system was transmissive, and the gap was 450 μm.

[0152] Under these conditions, the experiment of Example 3 was performed, and the results were as follows: the amplitude of signal W22 was 33.254, the phase was 3.135 [px], and the period was 12.465 [px]; the amplitude of signal W21 was 30.337, the phase was 3.628 [px], and the period was 12.462 [px]; the amplitude ratio was 1.10, and the period difference per pixel was 0.003 [px]; Example 3 was successful in focusing various precision alignment marks.

[0153] 43 to 45 are diagrams showing the experimental results of Example 4. In Example 4, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 50 mm, the F-number was 1.8, the magnification was 1.01, the object-side NA was 0.140, the optical system was transmissive, and the gap was 2900 μm.

[0154] Under these conditions, the experiment of Example 4 was performed, and the results were that the amplitude of signal W22 was 3.154, the phase was -1.939 [px], and the period was 12.453 [px]. The amplitude of signal W21 was 22.441, the phase was 1.835 [px], and the period was 12.473 [px]. The amplitude ratio was 0.14, and the period difference per pixel was 0.02 [px]. Example 4 was successful in focusing various precision alignment marks.

[0155] 46 to 48 are diagrams showing the experimental results of Example 5. In Example 5, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 50 mm, the F-number was 1.8, the magnification was 1.01, the object-side NA was 0.140, the optical system was transmissive, and the gap was 2950 μm.

[0156] Under these conditions, the experiment of Example 5 was performed, and the results were that the amplitude of signal W22 was 2.256, the phase was -0.148 [px], and the period was 12.475 [px]. The amplitude of signal W21 was 25.868, the phase was -2.071 [px], and the period was 12.469 [px]. The amplitude ratio was 0.09, and the period difference per pixel was 0.006 [px]. Example 5 was successful in focusing various precision alignment marks.

[0157] 49 to 51 are diagrams showing the experimental results of Comparative Example 2. In Comparative Example 2, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 50 mm, the F-number was 1.8, the magnification was 1.01, the object-side NA was 0.140, the optical system was transmissive, and the gap was 3050 μm.

[0158] Under these conditions, the experiment for Comparative Example 2 was performed, and the results were that the amplitude of signal W22 was 0.935, the phase was -0.134 [px], and the period was 3.340 [px]. The amplitude of signal W21 was 25.697, the phase was -1.874 [px], and the period was 12.469 [px]. The amplitude ratio was 0.04, and the period difference per pixel was 9.129 [px]. Comparative Example 2 failed to focus various precision alignment marks.

[0159] 52 to 54 are diagrams showing the experimental results of Example 6. In Example 6, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 75 mm, the F-number was 1.8, the magnification was 1.53, the object-side NA was 0.168, the optical system was transmissive, and the gap was 450 μm.

[0160] Under these conditions, the experiment of Example 6 was performed, and the results were that the amplitude of signal W22 was 19.293, the phase was 2.881 [px], and the period was 18.737 [px]. The amplitude of signal W21 was 23.960, the phase was 2.600 [px], and the period was 18.740 [px]. The amplitude ratio was 0.81, and the period difference per pixel was 0.003 [px]. Example 6 successfully focused various precision alignment marks.

[0161] 55 to 57 are diagrams showing the experimental results of Example 7. In Example 7, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 75 mm, the F-number was 1.8, the magnification was 1.53, the object-side NA was 0.168, the optical system was a transmission system, and the gap was 1750 μm.

[0162] Under these conditions, the experiment of Example 7 was performed, and the results were that the amplitude of signal W22 was 2.609, the phase was -4.421 [px], and the period was 18.734 [px]. The amplitude of signal W21 was 23.771, the phase was 2.308 [px], and the period was 18.736 [px]. The amplitude ratio was 0.11, and the period difference per pixel was 0.002 [px]. Example 7 was successful in focusing various precision alignment marks.

[0163] 58 to 60 are diagrams showing the experimental results of Comparative Example 3. In Comparative Example 3, the type of lens 22 was M5018-VSW, the length of the close-up ring 24 was 75 mm, the F-number was 1.8, the magnification was 1.53, the object-side NA was 0.168, the optical system was transmissive, and the gap was 1800 μm.

[0164] Under these conditions, the experiment for Comparative Example 3 was performed, and the results were that the amplitude of signal W22 was 33.254, the phase was 3.135 [px], and the period was 12.465 [px]. The amplitude of signal W21 was 30.337, the phase was 3.628 [px], and the period was 12.462 [px]. The amplitude ratio was 0.10, and the period difference per pixel was 0.0087 [px]. Comparative Example 3 failed to focus various precision alignment marks.

[0165] 61 to 63 are diagrams showing the experimental results of Example 8. In Example 8, the type of lens 22 was LED-BD-NIR-M5, the F-number was 0.6, the magnification was 5.00, the object-side NA was 0.650, the optical system was transmissive, and the gap was 450 μm.

[0166] Under these conditions, the experiment of Example 8 was performed, and the results were that the amplitude of signal W22 was 39.250, the phase was -3.695 [px], and the period was 59.917 [px]. The amplitude of signal W21 was 62.258, the phase was -0.691 [px], and the period was 59.923 [px]. The amplitude ratio was 0.63, and the period difference per pixel was 0.006 [px]. Example 8 was successful in focusing various precision alignment marks.

[0167] 64 to 66 are diagrams showing the experimental results of Example 9. In Example 9, the type of lens 22 was LED-BD-NIR-M5, the F-number was 0.6, the magnification was 5.00, the object-side NA was 0.650, the optical system was transmissive, and the gap was 700 μm.

[0168] Under these conditions, the experiment of Example 9 was performed. The amplitude of signal W22 was 8.382, the phase was 12.868 [px], and the period was 59.910 [px]. The amplitude of signal W21 was 63.732, the phase was 13.855 [px], and the period was 59.957 [px]. The amplitude ratio was 0.13, and the period difference per pixel was 0.047 [px]. Example 9 successfully focused various precision alignment marks.

[0169] 67 to 69 are diagrams showing the experimental results of Comparative Example 4. In Comparative Example 4, the type of lens 22 was LED-BD-NIR-M5, the F-number was 0.6, the magnification was 5.00, the object-side NA was 0.650, the optical system was transmissive, and the gap was 750 μm.

[0170] Under these conditions, the experiment for Comparative Example 4 was performed, and the results were that the amplitude of signal W22 was 3.351, the phase was 7.103 [px], and the period was 59.785 [px]. The amplitude of signal W21 was 62.684, the phase was 6.094 [px], and the period was 59.920 [px]. The amplitude ratio was 0.05, and the period difference per pixel was 0.135 [px]. Comparative Example 4 failed to focus various precision alignment marks.

[0171] 70 to 72 are diagrams showing the experimental results of Comparative Example 5. In Comparative Example 5, the type of lens 22 is OS-TCM1.0-H1.1-CEI, the F-number is 2.8, the magnification is 1.00, the object-side NA is 0.091, the optical system is reflective, and the gap is 450 μm.

[0172] Under these conditions, the experiment for Comparative Example 5 was performed, and the results were that the amplitude of signal W22 was 1.057, the phase was -1.226 [px], and the period was 12.050 [px]. The amplitude of signal W21 was 7.938, the phase was -1.862 [px], and the period was 6.076 [px]. The amplitude ratio was 0.13, and the period difference per pixel was 5.974 [px]. Comparative Example 5 failed to focus various precision alignment marks.

[0173] 1... Alignment device, 20... Camera, 22... Lens, 30... Fixed stage, 40... XYZθ axis movable stage, 50... Illumination device, 100... Control device, 110... Communication interface, 120... Input interface, 130... Output interface, 140... Memory 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 method for aligning an object, comprising: 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 same first periodic structure is formed; irradiating light onto the stacked first object and the second object; detecting a first signal which is a signal of the light that has passed through the first array formed on the first object; detecting a second signal which is a signal of the light that has passed through the second array formed on the second object; and calculating a positional deviation 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 a first surface or a second surface opposite to the first surface of the first object, and the second array is formed on either a third surface or a fourth surface opposite to the third surface of the second object, which does not face the first object.

2. The alignment method of claim 1, further comprising: a third array having a second periodic structure different from the first periodic structure formed on the first object; a fourth array having the second periodic structure formed on the second object; detecting a third signal which is a signal of the light that has passed through the third array formed on the first object; detecting a fourth signal which is a signal of the light that has passed through the fourth array formed on the second object; and calculating the positional deviation of the stacked first and second objects based on the first signal, the second signal, the third signal, and the fourth signal; wherein the third array is formed on one of the first and second surfaces of the first object; and the fourth array is formed on the surface of the third and fourth surfaces of the second object that does not face the first object.

3. The alignment method described in claim 1 or 2, further comprising adjusting the positions of the stacked first object and the stacked second object based on the calculated positional deviation, and wherein when the first object and the second object are stacked, the first array formed on the first object and the second array formed on the second object are formed so as not to overlap each other.

4. The alignment method according to claim 1 or 2, wherein the positional deviation between the first object and the second object is calculated using an optical system, the optical system including: a stage that adjusts the positions of the first object and the second object in the horizontal direction, the vertical direction, and a rotational direction on a horizontal plane; a light source that is positioned below the stage and irradiates the light; and a camera that is positioned above the stage and detects the light that has passed through the first object and the second object, and the light is near-infrared light.

5. The alignment method according to claim 1 or 2, wherein the positional deviation between the first object and the second object is calculated using an optical system, the optical system including: a stage that adjusts the positions of the first object and the second object in the horizontal direction, the vertical direction, and a rotational direction on a horizontal plane; a light source that is disposed inside the stage and irradiates the light; and a camera that is disposed above the stage and detects the light that has passed through the first object and the second object, and the light is near-infrared light.

6. The alignment method according to claim 4, wherein the distance between the first object and the second object that can be aligned is 2950 μm or less.

7. The alignment method according to claim 4, wherein when the distance between the first object and the second object is 1000 μm or more, the numerical aperture of the camera lens is 0.168 or less.

8. The alignment method according to claim 1 or 2, wherein the stacked first object and second object are used in the manufacture of any one of an optical semiconductor element, a semiconductor element, and an optical element.

9. A method for manufacturing a laminate including a first object and a second object, comprising: stacking the first object, on which a first array having a first periodic structure is formed, and the second object, on which a second array having the first periodic structure is formed; irradiating light onto the stacked first object and the second object; detecting a first signal, which is a signal of the light that has passed through the first array formed on the first object; detecting a second signal, which is a signal of the light that has passed through the second array formed on the second object; calculating a positional deviation of the stacked first object and the second object based on the first signal and the second signal; and adjusting the positions of the stacked first object and the second object based on the calculated positional deviation; wherein the first array is formed on either a first surface or a second surface opposite to the first surface of the first object; and the second array is formed on one of a third surface or a fourth surface opposite to the third surface of the second object, which does not face the first object.

10. The manufacturing method described in claim 9, further comprising: a third array having a second periodic structure different from the first periodic structure formed on the first object; a fourth array having the second periodic structure formed on the second object; detecting a third signal which is a signal of the light that has passed through the third array formed on the first object; detecting a fourth signal which is a signal of the light that has passed through the fourth array formed on the second object; and calculating a positional deviation of the stacked first and second objects based on the first signal, the second signal, the third signal, and the fourth signal; wherein the third array is formed on one of the first and second surfaces of the first object; and the fourth array is formed on one of the third and fourth surfaces of the second object that does not face the first object.

11. The manufacturing method according to claim 9 or 10, wherein the laminate is used for manufacturing any one of an optical semiconductor element, a semiconductor element, and an optical element.

12. A lithography method for transferring a pattern formed on one of a first object and a second object to the other, comprising: 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 object and the second object with light; detecting a first signal which is a signal of the light that has passed through the first array formed on the first object; detecting a second signal which is a signal of the light that has passed through the second array formed on the second object; calculating a positional deviation of the stacked first object and the second object based on the first signal and the second signal; and adjusting the positions of the stacked first object and the second object based on the calculated positional deviation, wherein the first array is formed on one of a first surface and a second surface opposite to the first surface of the first object; and the second array is formed on one of a third surface and a fourth surface opposite to the third surface of the second object that does not face the first object; A lithography method further comprising: when the first array is formed as the pattern in the first object, transferring the first array formed in the first object to the second object; and when the second array is formed as the pattern in the second object, transferring the second array formed in the second object to the first object.

13. The first object further has a third array formed thereon, the third array having a second periodic structure different from the first periodic structure, and the second object further has a fourth array formed thereon, the fourth array having the second periodic structure; detecting a third signal which is a signal of the light transmitted through the third array formed on the first object; detecting a fourth signal which is a signal of the light transmitted through the fourth array formed on the second object; calculating a positional deviation of the stacked first object and the second object based on the first signal, the second signal, the third signal, and the fourth signal; the third array is formed on one of the first surface and the second surface of the first object; the fourth array is formed on one of the third surface and the fourth surface of the second object that does not face the first object; and when the first array and the third array are formed as the pattern on the first object, transferring the first array and the third array formed on the first object to the second object.

13. The lithography method according to claim 12, further comprising: when the second array and the fourth array are formed in the second object as the pattern, transferring the second array and the fourth array formed in the second object to the first object.

14. An alignment device comprising: a detection unit that detects signals of light irradiated onto and transmitted through a first object and a second object that are stacked, the first object having a first array having a first periodic structure formed thereon, and a second object having a second array having the first periodic structure formed thereon; and a calculation unit that calculates a positional deviation of the stacked first object and the second object based on the signals, wherein the detection unit detects a first signal that is a signal of the light that has transmitted through the first array formed on the first object, and a second signal that is a signal of the light that has transmitted through the second array formed on the second object, and the calculation unit calculates the positional deviation based on the first signal and the second signal, wherein the first array is formed on either a first surface or a second surface opposite to the first surface of the first object, and the second array is formed on either a third surface or a fourth surface opposite to the third surface of the second object that does not face the first object.

15. The alignment device described in claim 14, wherein: the first object further has a third array formed thereon, the third array having a second periodic structure different from the first periodic structure; the second object further has a fourth array formed thereon, the fourth array having the second periodic structure; the detection unit further detects a third signal, which is a signal of the light that has passed through the third array formed on the first object, and a fourth signal, which is a signal of the light that has passed through the fourth array formed on the second object; the calculation unit calculates the positional deviation of the stacked first and second objects based on the first signal, the second signal, the third signal, and the fourth signal; the third array is formed on one of the first and second surfaces of the first object; and the fourth array is formed on the surface of the third and fourth surfaces of the second object that does not face the first object.

16. A program to be executed by a computer, comprising: detecting a signal of light irradiated onto and transmitted through a first object and a second object which are stacked, 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; calculating a positional deviation of the stacked first object and the second object based on the signal; detecting a first signal which is a signal of the light which has transmitted through the first array formed on the first object; detecting a second signal which is a signal of the light which has transmitted through the second array formed on the second object; calculating the positional deviation based on the first signal and the second signal; wherein the first array is formed on either a first surface or a second surface opposite to the first surface of the first object, and the second array is formed on either a third surface or a fourth surface opposite to the third surface of the second object which does not face the first object.

17. The program described in claim 16, further comprising: a third array having a second periodic structure different from the first periodic structure formed on the first object; a fourth array having the second periodic structure formed on the second object; detecting a third signal which is a signal of the light that has passed through the third array formed on the first object; detecting a fourth signal which is a signal of the light that has passed through the fourth array formed on the second object; and calculating a positional shift of the stacked first object and second object based on the first signal, the second signal, the third signal, and the fourth signal; wherein the third array is formed on one of the first surface and the second surface of the first object; and the fourth array is formed on the surface of the third surface or the fourth surface of the second object that does not face the first object.

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