Joining device and joining method

Abstract

The present invention provides a bonding device and bonding method for appropriately aligning the positions of substrates being bonded. The bonding device bonds a first substrate to a second substrate and comprises: a first holding portion that holds the first substrate; a second holding portion that holds the second substrate; a first imaging portion disposed on the first holding portion that captures an image of the second substrate held by the second holding portion; a first light irradiation portion disposed on the first holding portion that irradiates light toward the second substrate when the first imaging portion captures the image; a second imaging portion disposed on the second holding portion that captures the image of the first substrate held by the first holding portion; and a second light irradiation portion disposed on the second holding portion that irradiates light toward the first substrate when the second imaging portion captures the image. The first and second light irradiation portions are each connected to a first light source that irradiates white light.

Description

Technical Field

[0001] The present disclosure relates to a joining device and a joining method. Background Art

[0002] Patent Document 1 discloses a method for aligning a mask having a circuit pattern formed thereon with a pattern formed on a wafer in an exposure apparatus. According to Patent Document 1, images of alignment marks attached to the wafer and images of index marks on an index plate disposed within a surface conjugate with the wafer are captured and detected using an objective lens or the like. During this imaging, illumination light having a predetermined wavelength width is directed onto the wafer, for example, via an optical fiber. Alternatively, the wafer may be illuminated using reflected light from a reflector or a contact lamp, rather than using an optical fiber.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2006 / 025386 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The technology according to the present disclosure appropriately performs positional alignment between substrates during bonding.

[0008] Solutions for solving problems

[0009] One embodiment of the present disclosure is a joining device for joining a first substrate to a second substrate, which comprises: a first holding portion that holds the first substrate; a second holding portion that holds the second substrate; a first camera portion that is provided on the first holding portion and takes a picture of the second substrate held on the second holding portion; a first light irradiation portion that is provided on the first holding portion and irradiates light onto the second substrate when the first camera portion takes a picture; a second camera portion that is provided on the second holding portion and takes a picture of the first substrate held on the first holding portion; and a second light irradiation portion that is provided on the second holding portion and irradiates light onto the first substrate when the second camera portion takes a picture, wherein the first light irradiation portion and the second light irradiation portion are each connected to a first light source that irradiates white light.

[0010] Effects of the Invention

[0011] According to the present disclosure, it is possible to appropriately perform positional alignment between substrates during bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a side view schematically showing the structure of the stacked wafers.

[0013] Figure 2 This diagram illustrates the interference of light.

[0014] Figure 3 It is a plan view schematically showing the outline of the structure of the joining system.

[0015] Figure 4 It is a side view schematically showing the outline of the structure of the joining system.

[0016] Figure 5 It is a plan view schematically showing the outline of the structure of the bonding device.

[0017] Figure 6 It is a front view schematically showing the outline of the structure of the bonding device.

[0018] Figure 7 It is a side view schematically showing the outline of the structure of the bonding device.

[0019] Figure 8 This is a flowchart showing the main steps of the joining process.

[0020] Figure 9a to Figure 9d It is an explanatory diagram showing a main structure of an alignment process in a bonding apparatus.

[0021] Figure 10 It is an explanatory diagram showing the imaging result of the alignment mark.

[0022] Figure 11 It is an explanatory diagram showing a method of analyzing imaging results.

[0023] Figure 12 It is an explanatory diagram showing the wavelength range of irradiated light.

[0024] Figure 13 This is a side view schematically showing another structural outline of the joining device.

[0025] Description of Reference Numerals

[0026] 50: bonding device; 140: upper suction cup; 141: lower suction cup; 151: upper camera unit; 152: upper illuminating unit; 153: upper light source; 161: lower camera unit; 162: lower illuminating unit; 163: lower light source; Lw: white light; W: upper wafer; S: lower wafer. DETAILED DESCRIPTION

[0027] In recent years, semiconductor devices have become increasingly integrated. When multiple highly integrated semiconductor devices are arranged horizontally and connected by wiring for commercialization, there are concerns about increased wiring length, resulting in increased wiring resistance and increased wiring delay.

[0028] Therefore, a three-dimensional integration technology that stacks semiconductor devices three-dimensionally has been proposed. In this three-dimensional integration technology, for example, two semiconductor wafers (hereinafter referred to as "wafers") are bonded to form an overlapping wafer. In the formation of this overlapping wafer, the surfaces of the bonded wafers are modified by plasma treatment, and pure water is supplied to the modified surfaces to make them hydrophilic. Then, the surfaces of the hydrophilized wafers are bonded together by van der Waals forces and hydrogen bonds (intermolecular forces).

[0029] Figure 1 This is a side view schematically illustrating the structure of a stacked wafer T formed by bonding an upper wafer W and a lower wafer S. Hereinafter, the surface of the upper wafer W that is bonded to the lower wafer S is referred to as the front surface Wa, and the surface opposite to the front surface Wa is referred to as the back surface Wb. Similarly, the surface of the lower wafer S that is bonded to the upper wafer W is referred to as the front surface Sa, and the surface opposite to the front surface Sa is referred to as the back surface Sb.

[0030] The upper wafer W serving as the first substrate is, for example, a semiconductor wafer such as a silicon wafer, and has a device layer (not shown) including a plurality of circuits and other devices formed on its surface Wa. Furthermore, an oxide film Fw, such as a transparent film such as a SiO2 film (TEOS film), is formed on the device layer.

[0031] Furthermore, a plurality of alignment marks A are formed on the oxide film Fw for adjusting the horizontal position of the upper wafer W with respect to the lower wafer S when the upper wafer W is bonded to the lower wafer S. The number and arrangement of the alignment marks A are not limited to the illustrated examples and can be arbitrarily determined.

[0032] The lower wafer S, serving as the second substrate, is a semiconductor wafer such as a silicon wafer, and has an oxide film Fs, such as a SiO2 film (TEOS film), formed on its surface Sa. Furthermore, the lower wafer S functions as a protective member for protecting the device layer on the surface Wa of the upper wafer W. Furthermore, if multiple devices are formed on the surface Sa of the lower wafer S, a device layer (not shown) is formed on the surface Sa, similar to the upper wafer W.

[0033] Furthermore, a plurality of alignment marks B are formed on the oxide film Fs for adjusting the horizontal position of the lower wafer S with respect to the upper wafer W when the lower wafer S is bonded to the upper wafer W. The number and arrangement of the alignment marks B are not limited to the illustrated example and can be arbitrarily determined.

[0034] In addition, when the upper wafer W is joined to the lower wafer S, the surface of the aforementioned oxide film Fw is actually joined to the surface of the oxide film Fs. However, in order to simplify the description, the following description is sometimes described as joining "the surface Wa of the upper wafer W to the surface Sa of the lower wafer S".

[0035] When forming the stacked wafers T described above, it is important to align the upper wafer W with the lower wafer S in the horizontal direction. This alignment is performed by sequentially capturing images of alignment marks A and B using an imaging unit (e.g., a CCD camera) and aligning the horizontal positions of alignment marks A and B based on the captured images.

[0036] In this alignment, when imaging the alignment marks A and B, illumination light is irradiated onto the surfaces Wa and Sa of the upper wafer W and the lower wafer S. As this illumination light, for example, red light is generally used.

[0037] However, when red light is irradiated onto the surfaces Wa and Sa and an image is captured, light interference may occur in the oxide films Fw and Fs (transparent films) formed on the surfaces Wa and Sa of the upper wafer W and the lower wafer S. Furthermore, when light interference occurs in this manner, the brightness and contrast of the captured image may change significantly, making it impossible to properly identify the alignment marks A and B.

[0038] like Figure 2 As shown, the illumination light irradiating the upper wafer W is repeatedly reflected and refracted by each layer. For example, if the thickness of the oxide film Fw formed on the upper wafer W is non-uniform within the surface, the reflectivity of the illumination light within the surface of the upper wafer W is not constant. In this case, interference of the illumination light occurs in the oxide film Fw, and the brightness and contrast of the captured image vary, causing the identification color of the alignment marks A and B within the surface of the upper wafer W to change. Such changes in the identification color of the alignment marks A and B reduce the accuracy of position recognition of the alignment marks A and B. In other words, there is room for improvement in alignment in conventional bonding equipment.

[0039] Therefore, the inventors conducted in-depth research and discovered that using white light with a wide wavelength range as illumination for imaging alignment marks can improve position recognition accuracy. Patent Document 1 discloses the use of white light as illumination for horizontal alignment of the upper wafer W in an exposure apparatus. However, Patent Document 1 does not describe the advantages of using white light. Furthermore, there has been no prior research on the use of white light in bonding equipment, as the inventors have done.

[0040] The technology disclosed herein appropriately aligns substrates during bonding. The bonding apparatus of this embodiment is described below with reference to the accompanying drawings. In addition, in this specification and the accompanying drawings, elements having substantially the same functional structure are assigned the same reference numerals to omit repeated descriptions.

[0041] First, the configuration of a joining system 1 including a joining apparatus according to this embodiment will be described. Figure 3 、 Figure 4 1 and 2 are a top view and a side view schematically showing the structure of the bonding system 1. In the following, to clarify the positional relationship, mutually orthogonal X-axis, Y-axis, and Z-axis directions are defined, and the positive Z-axis direction is defined as the vertically upward direction.

[0042] like Figure 3 As shown, the bonding system 1 has a structure in which a loading and unloading station 2 and a processing station 3 are connected as a whole. For example, the loading and unloading station 2 is used to load and unload cassettes Cw, Cs, and Cs that can respectively accommodate a plurality of upper wafers W, a plurality of lower wafers S, and a plurality of stacked wafers T. T The processing station 3 includes various processing devices for processing the upper wafer W and the lower wafer S.

[0043] A cassette placement table 10 is provided in the loading / unloading station 2. In the example shown in the figure, a plurality of, for example, four cassettes Cw, Cs, Cs, and Cs are freely placed in a row along the X-axis direction on the cassette placement table 10. T In addition, the boxes Cw, Cs, and C T The number of is not limited to this embodiment and can be determined arbitrarily.

[0044] A wafer transfer area 20 is provided adjacent to the box loading platform 10 in the loading and unloading station 2. A wafer transfer device 22 that is free to move on a transfer path 21 extending in the X-axis direction is provided in the wafer transfer area 20. The wafer transfer device 22 has a transfer arm 23 that holds and transfers the upper wafer W, the lower wafer S, and the overlapping wafer T. The transfer arm 23 is configured to move freely in the horizontal direction, in the vertical direction, around the horizontal axis, and around the vertical axis. In addition, the number and structure of the transfer arms 23 are not limited to the present embodiment, and any structure can be adopted. Moreover, the wafer transfer device 22 is configured to be able to transfer the upper wafer W, the lower wafer S, and the overlapping wafer T to the box C of the box loading platform 10 and the conveying devices 60 and 61 described later.

[0045] The processing station 3 is provided with a plurality of, for example, three, processing blocks G1 to G3 equipped with various devices. For example, on the front side of the processing station 3 ( Figure 3 The first processing block G1 is provided on the back side of the processing station 3 ( Figure 3The second processing block G2 is provided on the positive X direction side of the processing station 3. Figure 3 A third processing block G3 is provided on the negative Y direction side of the PCB.

[0046] A surface modification device 30 is located in the first processing block G1. In the surface modification device 30, the upper wafer W and the lower wafer S are modified by plasma treatment. The number and arrangement of the surface modification devices 30 are not limited to the illustrated example. For example, multiple surface modification devices 30 may be arranged along the Y-axis. Furthermore, multiple surface modification devices 30 may be stacked, for example.

[0047] The second processing block G2 is provided with a surface hydrophilization device 40 and a bonding device 50. In the surface hydrophilization device 40, pure water is supplied to the upper wafer W and the lower wafer S for hydrophilization. In the bonding device 50, the upper wafer W and the lower wafer S, which have undergone surface modification and hydrophilization, are bonded.

[0048] The surface hydrophilization apparatus 40 and the bonding apparatus 50 are arranged in this order along the Y-axis direction, starting from the loading / unloading station 2. The number and arrangement of the surface hydrophilization apparatus 40 and the bonding apparatus 50 are not limited to the illustrated example. For example, the surface hydrophilization apparatus 40 and the bonding apparatus 50 may be stacked separately. The structure of the bonding apparatus 50 will be described later.

[0049] like Figure 4 As shown in FIG3 , the third processing block G3 is provided with conveyor devices 60 and 61. The conveyor devices 60 and 61 are stacked in this order from the bottom.

[0050] like Figure 3 As shown, in an area surrounded by the first to third processing blocks G1 to G3, a wafer transfer area 70 is formed. In the wafer transfer area 70, for example, a wafer transfer device 71 is disposed.

[0051] The wafer transport device 71 includes a transport arm 72 for holding and transporting the upper wafer W, lower wafer S, and overlapping wafer T. The transport arm 72 is configured to move freely horizontally, vertically, around a horizontal axis, and around a vertical axis. The number and structure of the transport arms 72 are not limited to this embodiment; any structure can be employed. Furthermore, the wafer transport device 71 is configured to transport the upper wafer W, lower wafer S, and overlapping wafer T to various processing devices within the surrounding first processing block G1, second processing block G2, and third processing block G3.

[0052] In the above-mentioned joining system 1, a control device 80 is provided. The control device 80 is, for example, a computer and has a program storage unit (not shown). The program storage unit stores programs for controlling various processes in the joining system 1. In addition, the program storage unit also stores the following programs: for controlling the operation of the drive system of the various processing devices, conveying devices, etc. mentioned above, to implement the joining process described later in the joining system 1. In addition, the above-mentioned programs can also be recorded on a storage medium H that can be read by a computer and installed from the storage medium H to the control device 80.

[0053] Next, the structure of the above-mentioned bonding apparatus 50 will be described. Figure 5 、 Figure 6 They are a top view and a side view schematically showing the outline of the structure of the joining device 50 , respectively.

[0054] like Figure 5 As shown, the bonding apparatus 50 includes a process container 100 with a sealed interior. A loading / unloading port 101 for the upper wafer W, lower wafer S, and stacked wafer T is formed on the side surface of the process container 100 on the wafer transfer area 70 side, and a shutter 102 is provided at the loading / unloading port 101.

[0055] The interior of the processing container 100 is divided into a transfer area R1 and a processing area R2 by an inner wall 103. The aforementioned loading / unloading port 101 is formed on a side surface of the processing container 100 within the transfer area R1. Furthermore, loading / unloading ports 104 for the upper wafer W, lower wafer S, and stacked wafer T are also formed in the inner wall 103.

[0056] A conveyor 110 is provided on the positive X-direction side of the transfer region R1 for temporarily placing the upper wafer W, lower wafer S, and stacked wafer T. The conveyor 110 can be formed in two stages, for example, and can simultaneously place any two of the upper wafer W, lower wafer S, and stacked wafer T.

[0057] A wafer transfer mechanism 111 is provided in transfer area R1. The wafer transfer mechanism 111 includes a transfer arm 112 that holds and transfers the upper wafer W, lower wafer S, and overlapping wafer T. The transfer arm 112 is configured to move horizontally, vertically, and about a vertical axis. Furthermore, the wafer transfer mechanism 111 is configured to transfer the upper wafer W, lower wafer S, and overlapping wafer T within transfer area R1 or between transfer area R1 and processing area R2.

[0058] A position adjustment mechanism 120 is provided on the negative X-axis side of transport region R1 to adjust the horizontal orientation of the upper wafer W and lower wafer S. The position adjustment mechanism 120 detects the position of the notches formed in the upper wafer W and lower wafer S and rotates the upper wafer W and lower wafer S to adjust the positions of the notches, thereby adjusting the horizontal orientation.

[0059] Furthermore, a flipping mechanism 130 is provided in the transport region R1 for flipping the top and bottom surfaces of the upper wafer W. The flipping mechanism 130 is provided with a holding arm 131 that holds and flips the upper wafer W. The holding arm 131 is configured to move horizontally, vertically, around a horizontal axis, and around a vertical axis. Furthermore, the flipping mechanism 130 is configured to transfer the upper wafer W between the position adjustment mechanism 120 and an upper suction cup 140 (described later).

[0060] like Figure 5 and Figure 6 As shown, processing region R2 is provided with an upper suction cup 140 as a first holding portion, which suction-holds an upper wafer W on its lower surface; and a lower suction cup 141 as a second holding portion, which places and suction-holds a lower wafer S on its upper surface. The lower suction cup 141 is configured to be disposed below the upper suction cup 140 and to be arranged to face the upper suction cup 140. In other words, the upper wafer W held by the upper suction cup 140 and the lower wafer S held by the lower suction cup 141 can be arranged to face each other.

[0061] Figure 7 It is a side view schematically showing the internal structure of the processing region R2.

[0062] like Figure 6 、 Figure 7 As shown, the upper suction cup 140 is supported by the upper suction cup support portion 150. The upper suction cup support portion 150 is disposed on the top surface of the processing container 100. That is, the upper suction cup 140 is fixed and disposed on the top surface of the processing container 100 via the upper suction cup support portion 150.

[0063] The upper chuck support portion 150 is further provided with an upper imaging unit 151 as a first imaging unit that captures an image of the surface Sa of the lower wafer S held by the lower chuck 141, and an upper illuminating unit 152 as a first light irradiating unit that irradiates illumination light toward the lower wafer S while the upper imaging unit 151 is capturing images. The upper imaging unit 151 and the upper illuminating unit 152 are disposed adjacent to the upper chuck 140. The number and arrangement of the upper imaging units 151 and the upper illuminating unit 152 are not limited to this example and can be arbitrarily determined.

[0064] The upper imaging unit 151 uses, for example, a CCD camera.

[0065] like Figure 7 As shown, an upper light source 153 as a first light source is connected to the upper irradiation unit 152. As the light irradiated to the surface Sa of the lower wafer S, white light (for example, a white LED) is selected.

[0066] like Figure 6 、 Figure 7 As shown, the lower suction cup 141 is supported by a lower suction cup support portion 160. The lower suction cup support portion 160 is connected to a moving mechanism 170 and is configured to freely move the lower suction cup 141 in the horizontal direction, in the vertical direction, and around the vertical axis.

[0067] Furthermore, the lower chuck support portion 160 is provided with a lower imaging unit 161 as a second imaging unit that captures an image of the surface Wa of the upper wafer W held by the upper chuck 140, and a lower illuminating unit 162 as a second light irradiating unit that irradiates illumination light toward the upper wafer W while the lower imaging unit 161 is capturing images. The lower imaging unit 161 and the lower illuminating unit 162 are disposed adjacent to the lower chuck 141. The number and arrangement of the lower imaging units 161 and the lower illuminating unit 162 are not limited to this example and can be arbitrarily determined.

[0068] The lower imaging unit 161 uses, for example, a CCD camera.

[0069] like Figure 7 As shown, a lower light source 163 as a first light source is connected to the lower irradiation unit 162. As the light irradiated to the surface Wa of the upper wafer W, white light (for example, a white LED) is selected.

[0070] In addition, you can Figure 7 As shown, the upper light source 153 and the lower light source 163 are independently provided for the upper illuminating portion 152 and the lower illuminating portion 162 , respectively. Alternatively, the upper illuminating portion 152 and the lower illuminating portion 162 may be connected to a common light source.

[0071] The moving mechanism 170 is provided on the lower surface side of the lower suction cup support part 160 and is mounted on a pair of guide rails 171, 171 extending in the Y-axis direction. Moreover, the lower suction cup support part 160 is configured to be movable in the Y-axis direction along the guide rails 171.

[0072] The moving mechanism 170 includes a pair of guide rails 172 extending in the X-axis direction. The lower chuck support 160 is configured to be movable in the X-axis direction along the guide rails 172 .

[0073] Furthermore, a target 180 is provided in the processing region R2 for horizontally aligning the upper imaging unit 151 and the lower imaging unit 161. When aligning the upper imaging unit 151 and the lower imaging unit 161, the target 180 is positioned between the upper imaging unit 151 and the lower imaging unit 161.

[0074] The bonding apparatus 50 according to the present embodiment is configured as described above. Next, a bonding process of wafers performed using the bonding system 1 including the bonding apparatus 50 will be described. Figure 8 This is a flowchart showing the main steps of the joining process.

[0075] First, a cassette Cw containing a plurality of upper wafers W, a cassette Cs containing a plurality of lower wafers S, and an empty cassette C T It is placed on a predetermined cassette placement plate 11 of the loading / unloading station 2. Thereafter, the upper wafer W in the cassette Cw is taken out by the wafer transfer device 22 and transferred to the conveyor device 60 of the third processing block G3.

[0076] Next, the upper wafer W is transported to the surface modification device 30 of the first processing block G1 by the wafer transfer device 71. In the surface modification device 30, oxygen and nitrogen as processing gases are excited in a reduced pressure environment to form plasma and ionize them. The oxygen ions and nitrogen ions are irradiated onto the surface Wa of the upper wafer W, thereby performing plasma treatment on the surface Wa. In addition, the surface Wa of the upper wafer W is modified ( Figure 8 Step P1).

[0077] The upper wafer W after the surface Wa is modified is transported to the surface hydrophilization device 40 of the second processing block G2 by the wafer transport device 71. In the surface hydrophilization device 40, the upper wafer W held on the spin chuck is rotated, and pure water is supplied to the upper wafer W. As a result, the supplied pure water diffuses on the surface Wa of the upper wafer W, and hydroxyl groups (silanol groups) are attached to the surface Wa modified by the surface modification device 30 to hydrophilize the surface Wa. In addition, the upper wafer W ( Figure 8 Step P2).

[0078] Next, the upper wafer W is transported to the bonding device 50 of the second processing block G2 by the wafer transport device 71. The upper wafer W transported to the bonding device 50 is transported to the position adjustment mechanism 120 via the conveyor 110 and the wafer transport mechanism 111. Then, the horizontal direction of the upper wafer W is adjusted by the position adjustment mechanism 120 ( Figure 8 Step P3).

[0079] Next, the upper wafer W whose horizontal orientation is adjusted is transferred to the holding arm 131 of the reversing mechanism 130. Next, the holding arm 131 is reversed around the horizontal axis in the transport region R1, thereby reversing the front and back surfaces of the upper wafer W ( Figure 8 In step P4), the surface Wa of the upper wafer W is directed downward.

[0080] Next, the holding arm 131 rotates around the vertical axis and moves below the upper suction cup 140 of the processing area R2. Then, the back surface Wb ( Figure 8 Step P5).

[0081] While the above-described steps P1 to P5 are being performed on the upper wafer W, the lower wafer S is processed subsequent to the upper wafer W.

[0082] First, the lower wafer S in the cassette Cs is taken out by the wafer transfer device 22 and transferred to the conveyor device 60 of the processing station 3 .

[0083] Next, the lower wafer S is transferred to the surface modification device 30 by the wafer transfer device 71, and the surface Sa of the lower wafer S is modified ( Figure 8 In addition, the surface Sa of the lower wafer S in step P6 is modified by the same method as the above-mentioned step P1.

[0084] The lower wafer S with the modified surface Sa is transported to the surface hydrophilizing device 40 by the wafer transport device 71, and the surface Sa is hydrophilized and cleaned at the same time. Figure 8 In step P7, the surface Sa of the lower wafer S is hydrophilized and cleaned by the same method as in step P2.

[0085] Next, the lower wafer S is transported to the bonding device 50 by the wafer transport device 71. The lower wafer S transported to the bonding device 50 is transported to the position adjustment mechanism 120 via the conveyor 110 and the wafer transport mechanism 111. Then, the horizontal direction of the lower wafer S is adjusted by the position adjustment mechanism 120 ( Figure 8 Step P8).

[0086] Next, the lower wafer S, whose horizontal orientation is adjusted, is moved to the upper side of the lower suction cup 141 of the processing area R2 by the wafer transfer mechanism 111. Then, the back side Sb ( Figure 8 Step P9).

[0087] Next, when the upper wafer W and the lower wafer S are respectively held by the upper suction cup 140 and the lower suction cup 141, the upper wafer W and the lower wafer S are aligned in the horizontal direction ( Figure 8 Step P10).

[0088] Figure 9a to Figure 9d 1 is an explanatory diagram schematically showing a state of alignment processing in the bonding apparatus 50 .

[0089] During the alignment process in the bonding device 50, first, as shown in FIG. Figure 9aAs shown, the horizontal positions of the upper imaging unit 151 and the lower imaging unit 161 are adjusted. Specifically, the lower chuck support unit 160 is moved horizontally so that the lower imaging unit 161 is positioned below the upper imaging unit 151. The target 180 is then confirmed by the upper and lower imaging units 151, and the lower chuck support unit 160 is moved so that the horizontal positions of the upper and lower imaging units 151 and 161 are aligned. At this point, the upper imaging unit 151 is fixed to the processing chamber 100, so only the lower imaging unit 161 needs to be moved, allowing the horizontal positions of the upper and lower imaging units 151 and 161 to be appropriately adjusted.

[0090] Next, if Figure 9b 、 Figure 9c As shown, the lower chuck support unit 160 is moved horizontally, and the lower imaging unit 161 sequentially captures images of the plurality of alignment marks A formed on the upper wafer W. Simultaneously, the upper imaging unit 151 sequentially captures images of the plurality of alignment marks B formed on the lower wafer S.

[0091] When the upper imaging unit 151 and the lower imaging unit 161 are used to capture images of the alignment marks A and B, illumination light is irradiated from the upper irradiation unit 152 and the lower irradiation unit 162 toward the alignment marks A and B. For example, white light Lw is used as the illumination light.

[0092] The images captured by the upper camera unit 151 and the lower camera unit 161 are output to the control device 80. Figure 9d As shown, the control device 80 moves the lower chuck 141 to a position where the alignment mark A on the upper wafer W and the alignment mark B on the lower wafer S are aligned based on the image captured by the upper imaging unit 151 and the image captured by the lower imaging unit 161 .

[0093] When the alignment of the upper wafer W and the lower wafer S is completed, the lower chuck support 160 is moved in the vertical direction to adjust the vertical position of the upper chuck 140 and the lower chuck 141. In this way, the vertical position between the upper wafer W held on the upper chuck 140 and the lower wafer S held on the lower chuck 141 is adjusted ( Figure 8 In step P11 , the distance between the surface Sa of the lower wafer S and the surface Wa of the upper wafer W is, for example, 50 μm to 200 μm.

[0094] Next, the upper wafer W and the lower wafer S are bonded together ( Figure 8Step P12). During the bonding process, while the upper wafer W and the lower wafer S are held on the upper suction cup 140 and the lower suction cup 141, respectively, the center of the upper wafer W is brought into contact with and pressed against the center of the lower wafer S, thereby starting the bonding process. Specifically, since the surface Wa of the upper wafer W and the surface Sa of the lower wafer S are modified in steps P1 and P6, van der Waals forces are generated between the surface Wa of the upper wafer W and the surface Sa of the lower wafer S, thereby bonding the surface Wa of the upper wafer W and the surface Sa of the lower wafer S. Furthermore, since the surface Wa of the upper wafer W and the surface Sa of the lower wafer S are hydrophilized in steps P2 and P7, the hydrophilic groups between the surfaces Wa and Sa form hydrogen bonds, thereby further strengthening the bonding.

[0095] When the upper wafer W and lower wafer S initially come into contact at their centers, the area of ​​bonding, achieved through van der Waals forces and hydrogen bonding, gradually expands from the center toward the periphery. Then, when the entire surface Wa of the upper wafer W and the entire surface Sa of the lower wafer S come into contact, the bonding is complete, forming an overlapping wafer T.

[0096] The stacked wafers T are transported to the conveyor 61 by the wafer transport device 71 and then to the cassette C on the cassette mounting plate 11 by the wafer transport device 22 of the loading / unloading station 2. T In this way, a series of joining processes in the joining system 1 are completed.

[0097] According to the bonding apparatus 50 according to the above-described embodiment, when imaging the alignment marks A and B during alignment of the upper wafer W and the lower wafer S, the upper wafer W and the lower wafer S are irradiated with white light Lw as illumination light.

[0098] Here, if Figure 1 As shown, when a transparent film, for example, a SiO2 film (TEOS film) as an oxide film Fw is formed on the surface Wa of the upper wafer W and the surface Sa of the lower wafer S, as shown in FIG. Figure 2 As shown, light interference occurs, and the positions of the alignment marks A and B may not be properly recognized.

[0099] Figure 10 This is an example of a captured image obtained when using illumination lights with different wavelength widths to capture the alignment mark A. In addition, as "illumination lights with different wavelength widths", illumination lights with different wavelength widths are used. Figure 12 The alignment mark A was imaged using (a) red light Lr, (b) blue light Lb, and (c) white light Lw of the wavelength widths shown. Specifically, the red light Lr has a wavelength of approximately 660 nm, the blue light Lb has a wavelength of approximately 465 nm, and the white light Lw has a wavelength width of approximately 430 nm to 700 nm.

[0100] like Figure 10 As shown in (a) of FIG. 1 , when red light Lr is irradiated onto alignment mark A and an image is captured, for example, in image No. 1, alignment mark A is recognized as white, with its outer periphery recognized as black. In contrast, in image No. 7, the contrast is reversed, with alignment mark A recognized as black and its outer periphery recognized as white. Furthermore, for example, in image No. 7, the contrast ratio between alignment mark A and its outer periphery is high, and the boundary between alignment mark A is clear. In contrast, in image No. 5, the contrast ratio is low, and the boundary is unclear. Furthermore, in some cases, the contrast ratio of the recognized alignment marks A varies in the circumferential direction (the four sides of the quadrilateral), as shown in image No. 6.

[0101] like Figure 10 As shown in (b) of FIG. 1 , when blue light Lb is irradiated onto alignment mark A and an image is captured, the image results are similar to those obtained using red light Lr. For example, in image No. 1, alignment mark A is recognized as white, with its outer periphery recognized as black. In contrast, in image No. 2, the contrast is reversed, with alignment mark A recognized as black, with its outer periphery recognized as white. Furthermore, in image No. 6, for example, the contrast ratio is high, and the boundary of alignment mark A is distinct. In contrast, in image No. 7, the contrast ratio is low, and the boundary of alignment mark A is indistinct. Furthermore, the contrast ratios of the recognized alignment marks A may vary in the circumferential direction.

[0102] In this manner, for example, when red light Lr or blue light Lb is used as illumination light during alignment, the imaging results of the upper imaging unit 151 and the lower imaging unit 161 differ. Furthermore, when such a deviation occurs in the imaging results, the position recognition accuracy of the alignment mark A decreases, causing alignment errors.

[0103] Figure 11 This is an explanatory diagram showing an example of a processing method for identifying the position of the alignment mark A based on the image data obtained by the camera. The position of the alignment mark A is identified by identifying the boundary of the alignment mark A obtained by the camera. In this case, Figure 11 As shown, the boundary of the alignment mark A is recognized by graphing the contrast of the captured image data.

[0104] Specifically, if Figure 11 As shown in the graph, the black and white levels in the captured image are digitized to form a curve on the vertical axis, and the maximum value is calculated by differentiating it. The position showing the maximum value is determined as the boundary of the alignment mark A.

[0105] Here, if Figure 10 (a) Figure 10As shown in (b), if the contrast of the imaged alignment mark A is reversed, the calculated maximum value is reversed in sign, and thus the boundary may not be properly recognized. Furthermore, if the contrast ratio at the boundary of the imaged alignment mark A is low, the difference between the digitized black and white values ​​becomes small, and thus the boundary may not be properly recognized.

[0106] As described above, when variations occur in the imaging results of the alignment marks A, variations occur in the position recognition accuracy of the alignment marks A, and as a result, the upper wafer W and the lower wafer S cannot be properly aligned.

[0107] On the other hand, Figure 10 As shown in (c), when white light Lw is irradiated onto the alignment marks A and an image is captured, the brightness and contrast of the alignment marks A that are recognized are uniform, that is, stable. With such uniform position recognition accuracy, the position recognition accuracy of the upper wafer W and the lower wafer S can be stabilized across the entire surface, enabling proper alignment of the upper wafer W and the lower wafer S.

[0108] This is believed to be due to the Figure 12 The white light Lw shown has a wide wavelength range (multiple wavelength ranges), and therefore can average out the effects of light interference in the transparent film. Specifically, for example, even if light interference occurs within the wavelength range of the red light Lr component of white light Lw, it is believed that the boundary of the alignment mark A can be properly identified using light in other wavelength ranges (for example, the wavelength range of the blue light Lb component), thereby achieving the same imaging results without being affected by light interference within a certain wavelength range.

[0109] By irradiating the upper wafer W and the lower wafer S with white light Lw in this manner, stable imaging results can be obtained, that is, alignment can be performed appropriately without being affected by light interference in the transparent film.

[0110] Furthermore, according to the above embodiment, a white LED is used as the first light source to emit white light Lw, but the irradiation method of the white light Lw is not limited thereto. For example, a plurality of colors (for example, red, green, and blue) can be emitted simultaneously to produce a white light Lw. Figure 12 The wide range of wavelengths shown illuminates and thus synthesizes white light Lw.

[0111] Furthermore, as described above, white light Lw can average the influence of light interference to obtain the same imaging result. On the contrary, compared with the case of using red light Lr and blue light Lb for imaging, the resolution of the image (the contrast ratio at the boundary of the alignment mark A) is reduced. Figure 10As shown, the boundary of the alignment mark A is also imaged blurry.

[0112] However, when imaging is performed while irradiating white light Lw, the resolution decreases uniformly over the entire circumference of the alignment mark A (the four sides of the quadrilateral), so there is no variation in the position recognition accuracy in the circumferential direction of the alignment mark A. In other words, the alignment accuracy does not deteriorate.

[0113] In the above embodiment, the upper irradiation unit 152 and the lower irradiation unit 162 are respectively connected to the upper light source 153 and the lower light source 163 for irradiating white light Lw, but the number of light sources connected to the upper irradiation unit 152 and the lower irradiation unit 162 is not limited thereto.

[0114] For example, you can also Figure 13 As shown, the upper light source 153 and the lower light source 163 are further connected to an upper light source 154 and a lower light source 164 as a second light source for emitting light other than white (for example, red light Lr). Preferably, in this case, these upper light sources 153, 154 and lower light sources 163, 164 can be configured to switch between the lights they emit via optical path switching units 155, 165.

[0115] As described above, when imaging the alignment mark A using red light Lr or blue light Lb, the imaging results (e.g., brightness and contrast ratio) differ. On the other hand, the resolution of the captured image may be improved compared to imaging using white light Lw. Furthermore, when imaging data can be obtained at such a high resolution, the boundaries of the alignment mark A can be more accurately identified, which can improve alignment accuracy.

[0116] Therefore, by Figure 13 As shown, a plurality of light sources are connected to the upper light source 153 and the lower light source 163 , and the irradiated light can be changed based on the surface conditions of the upper wafer W and the lower wafer S (eg, the thickness of the transparent film and its in-plane uniformity).

[0117] Specifically, for example, a configuration may be employed in which red light Lr is normally irradiated for alignment, and white light Lw is irradiated when the desired position recognition accuracy is not achieved. Alternatively, for example, a configuration may be employed in which white light Lw is normally irradiated for alignment, and red light Lr is irradiated when higher alignment accuracy is required.

[0118] Alternatively, for example, the in-plane uniformity of the transparent film formed on the upper wafer W and the lower wafer S loaded into the bonding apparatus 50 may be measured in advance, and the irradiation of the red light Lr and the white light Lw may be switched based on the measured in-plane uniformity.

[0119] Alternatively, for example, when a transparent film that causes light interference is formed on the upper wafer W or the lower wafer S, white light Lw may be irradiated, and when no transparent film is formed, red light Lr may be irradiated.

[0120] In addition, the upper irradiation part 152 and the lower irradiation part 162 may be as follows Figure 7 As shown, the upper light source 153 and the lower light source 163 are provided separately, but a common light source may be connected to the upper illuminating portion 152 and the lower illuminating portion 162 .

[0121] In addition, the number of light sources connected to the upper illuminating unit 152 and the lower illuminating unit 162 is not limited to the example described above, and more light sources may be connected to each of them.

[0122] Furthermore, as described above, when synthesizing white light Lw by simultaneously emitting light of multiple colors, upper light source 153 serving as a first light source for emitting white light and upper light source 154 serving as a second light source for emitting light other than white light may be used in combination. Similarly, lower light source 163 serving as a first light source and lower light source 164 serving as a second light source may be used in combination.

[0123] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope of the appended claims and the spirit thereof.

[0124] For example, the technical content involved in the present disclosure is applied to a joining device in the above-mentioned embodiment, but it can also be applied to other devices, such as a molding device, as long as the device requires alignment.

[0125] In addition, the following structures also belong to the technical scope of the present disclosure.

[0126] (1) A bonding apparatus for bonding a first substrate to a second substrate, the bonding apparatus comprising:

[0127] a first holding portion that holds the first substrate;

[0128] a second holding portion that holds the second substrate;

[0129] a first imaging unit, which is provided on the first holding unit and captures an image of the second substrate held by the second holding unit;

[0130] a first light irradiation unit, which is provided on the first holding unit and irradiates light toward the second substrate when the first imaging unit is imaging;

[0131] a second imaging unit provided on the second holding unit and configured to capture an image of the first substrate held by the first holding unit; and

[0132] a second light irradiation unit provided on the second holding unit and irradiating light toward the first substrate when the second imaging unit is imaging;

[0133] The first light irradiation unit and the second light irradiation unit are each connected to a first light source that irradiates white light.

[0134] According to (1) above, the position recognition accuracy of the alignment mark formed on the substrate can be improved by irradiating the substrate with white light and capturing an image.

[0135] (2) The bonding device according to (1), wherein:

[0136] The first light irradiation unit and the second light irradiation unit are connected to a second light source that irradiates light other than white.

[0137] The first light irradiation unit and the second light irradiation unit are capable of switching between irradiation with light from the first light source and irradiation with light from the second light source.

[0138] According to (2) above, the irradiated light can be switched according to the condition of the transparent film formed on the substrate, so that the position recognition accuracy of the alignment mark can be further improved.

[0139] (3) A bonding method for bonding substrates, the bonding method comprising:

[0140] performing position alignment between the first substrate and the second substrate; and

[0141] bonding the first substrate and the second substrate,

[0142] Wherein, the position alignment includes:

[0143] capturing an image of the second substrate irradiated with light by the first light irradiation unit; and

[0144] capturing an image of the first substrate irradiated with light by the second light irradiation unit,

[0145] The light irradiated from each of the first light irradiation section and the second light irradiation section is white light irradiated from a first light source.

[0146] (4) The joining method according to (3), wherein:

[0147] The first light irradiation unit and the second light irradiation unit are each connected to a second light source that irradiates light other than white.

[0148] The first light irradiation section and the second light irradiation section are capable of switching between irradiation with light from the first light source and irradiation with light from the second light source.

[0149] (5) The joining method according to (4), wherein:

[0150] When a transparent film is formed on the second substrate, the first light irradiation unit irradiates light from the first light source.

[0151] When the transparent film is not formed on the second substrate, the first light irradiation unit irradiates light from the second light source.

[0152] (6) The joining method according to (4) or (5), wherein:

[0153] When a transparent film is formed on the first substrate, the second light irradiation unit irradiates light from the first light source.

[0154] When the transparent film is not formed on the first substrate, the second light irradiation unit irradiates light from the second light source.

Claims

1. A bonding apparatus for bonding a first substrate to a second substrate, the bonding apparatus comprising: a first holding portion that holds the first substrate; a second holding portion that holds the second substrate; a first imaging unit, which is provided on the first holding unit and captures an image of the second substrate held by the second holding unit; a first light irradiation unit, which is provided on the first holding unit and irradiates light toward the second substrate when the first imaging unit is performing imaging; a second imaging unit, which is provided on the second holding unit and captures an image of the first substrate held by the first holding unit; as well as a second light irradiation unit provided on the second holding unit and irradiating light toward the first substrate when the second imaging unit is imaging; The first light irradiation unit and the second light irradiation unit are each connected to a first light source that irradiates white light. A plurality of alignment marks are formed on each of the first substrate and the second substrate. When the second substrate is imaged by the first imaging unit and white light is irradiated from the first light irradiation unit to the second substrate, the first light irradiation unit only irradiates white light; and when the first substrate is imaged by the second imaging unit and white light is irradiated from the second light irradiation unit to the first substrate, the second light irradiation unit only irradiates white light.

2. The joining device according to claim 1, characterized in that The first light irradiation unit and the second light irradiation unit are connected to a second light source that irradiates light other than white. The first light irradiation unit and the second light irradiation unit are capable of switching between irradiation with light from the first light source and irradiation with light from the second light source.

3. A bonding method for bonding substrates, the bonding method comprising: performing position alignment of the first substrate and the second substrate; as well as bonding the first substrate and the second substrate, Wherein, the position alignment includes: capturing an image of the second substrate irradiated with light by the first light irradiation unit; and capturing an image of the first substrate irradiated with light by the second light irradiation unit, The light irradiated from each of the first light irradiation unit and the second light irradiation unit is white light irradiated from a first light source. A plurality of alignment marks are formed on each of the first substrate and the second substrate. When the second substrate is imaged and white light is irradiated from the first light irradiation section to the second substrate, the first light irradiation section irradiates only white light. When the first substrate is imaged and white light is irradiated from the second light irradiation section to the first substrate, the second light irradiation section irradiates only white light.

4. The bonding method according to claim 3, wherein: The first light irradiation unit and the second light irradiation unit are each connected to a second light source that irradiates light other than white. The first light irradiation unit and the second light irradiation unit are capable of switching between irradiation with light from the first light source and irradiation with light from the second light source.

5. The bonding method according to claim 4, wherein: When a transparent film is formed on the second substrate, the first light irradiation unit irradiates light from the first light source. When the transparent film is not formed on the second substrate, the first light irradiation unit irradiates light from the second light source.

6. The joining method according to claim 4 or 5, characterized in that: When a transparent film is formed on the first substrate, the second light irradiation unit irradiates light from the first light source. When the transparent film is not formed on the first substrate, the second light irradiation unit irradiates light from the second light source.

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