JP6412804B2 - Joining method and joining system - Google Patents

Description

  The disclosed embodiments relate to a bonding method and a bonding system.

  Conventionally, in the manufacturing process of a semiconductor device, a bonding process for bonding two substrates may be performed. For example, when manufacturing a semiconductor device including a back-illuminated image sensor, a bonding process is performed in which a second substrate is bonded to a first substrate on which a semiconductor element such as a photodiode is formed.

  The joining system that performs the joining process includes, for example, a surface hydrophilizing device that hydrophilizes the surfaces to be joined of the first and second substrates, and a joining device that joins the substrates whose surfaces are hydrophilized by the surface hydrophilizing device. With. In such a bonding system, the surface of the substrate is hydrophilized by supplying pure water to the surface of the substrate in the surface hydrophilizing device, and then the substrates are bonded to each other by van der Waals force and hydrogen bond (intermolecular force) in the bonding device. Join (refer to Patent Document 1).

JP2011-187716A

  However, when the above-described bonding system is used, air bubbles may be generated between the bonded substrates depending on the bonding state between the first substrate and the second substrate in the bonding apparatus.

  An object of one embodiment of the present invention is to provide a bonding method and a bonding system that can appropriately bond the substrates by suppressing generation of bubbles between the substrates.

The joining method according to one aspect of the embodiment includes a surface modification step, a surface hydrophilization step, a joining step, and a pressurizing step. In the surface modification step, the surfaces to be joined of the first substrate and the second substrate are modified. In the surface hydrophilization step, the modified surfaces of the first substrate and the second substrate are hydrophilized. In the bonding step, the hydrophilized first substrate and the second substrate are bonded by an intermolecular force under normal temperature and normal pressure. The pressurizing step raises the temperature of the superposed substrate on which the first substrate and the second substrate are bonded to a predetermined temperature higher than the normal temperature, and pressurizes the superposed substrate at the predetermined temperature. In the pressurizing step, the superposed substrate is placed on and supported on a support portion which is provided on a surface of the second flat plate portion positioned below the superposed substrate and faces the superposed substrate. The heating of the superposed substrate is started by a second heating mechanism provided on the second flat plate portion while being supported by the support portion, and the superposed substrate is heated to the predetermined temperature while the support portion is lowered. Let

  According to one aspect of the embodiment, the generation of bubbles between the substrates can be suppressed and the substrates can be appropriately bonded to each other.

FIG. 1 is a schematic plan view showing the configuration of the joining system according to the first embodiment. FIG. 2 is a schematic side view of the first substrate and the second substrate. FIG. 3 is a schematic plan view showing the configuration of the bonding apparatus. FIG. 4 is a schematic side view showing the configuration of the bonding apparatus. FIG. 5 is a schematic side view showing the configuration of the position adjusting mechanism. FIG. 6 is a schematic plan view showing the configuration of the reversing mechanism. FIG. 7 is a schematic side view showing the configuration of the reversing mechanism. FIG. 8 is a schematic side view showing the configuration of the reversing mechanism. FIG. 9 is a schematic side view showing the configuration of the holding arm and the holding member. FIG. 10 is a schematic side view showing the internal configuration of the bonding apparatus. FIG. 11 is a schematic side view showing configurations of the upper chuck and the lower chuck. FIG. 12 is a schematic plan view when the upper chuck is viewed from below. FIG. 13 is a schematic plan view when the lower chuck is viewed from above. FIG. 14A is an operation explanatory diagram of the bonding apparatus. FIG. 14B is an operation explanatory diagram of the bonding apparatus. FIG. 14C is an operation explanatory diagram of the bonding apparatus. FIG. 14D is an operation explanatory diagram of the bonding apparatus. FIG. 14E is an explanatory diagram of the operation of the bonding apparatus. FIG. 14F is an operation explanatory diagram of the bonding apparatus. FIG. 14G is an operation explanatory diagram of the bonding apparatus. FIG. 14H is an operation explanatory diagram of the bonding apparatus. FIG. 15 is a schematic side view showing the configuration of the preheating device. FIG. 16 is a schematic side view showing the configuration of the pressure device. FIG. 17 is a schematic side view showing the configuration of the second flat plate portion. FIG. 18 is a flowchart illustrating a part of a processing procedure of processing executed by the joining system. FIG. 19 is a flowchart showing the processing procedure of the pressurizing process for the overlapped wafer. FIG. 20A is an operation explanatory diagram of the pressurizing device. FIG. 20B is an operation explanatory diagram of the pressurizing device. FIG. 20C is an operation explanatory diagram of the pressurizing device. FIG. 21 is a schematic side view showing the configuration of the second flat plate portion according to the second embodiment. FIG. 22 is a schematic plan view when the second flat plate portion according to the second embodiment is viewed from above. FIG. 23 is a flowchart showing a processing procedure of processing for sucking and holding a superposed wafer by the second flat plate portion. FIG. 24A is an operation explanatory diagram of the second flat plate portion. FIG. 24B is an operation explanatory diagram of the second flat plate portion. FIG. 24C is an operation explanatory diagram of the second flat plate portion.

  Hereinafter, embodiments of a bonding method and a bonding system disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

(First embodiment)
<1. Structure of joining system>
First, the configuration of the joining system according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic plan view showing the configuration of the joining system according to the first embodiment. FIG. 2 is a schematic side view of the first substrate and the second substrate. In the following, in order to clarify the positional relationship, the X-axis direction, the Y-axis direction, and the Z-axis direction that are orthogonal to each other are defined, and the positive direction of the Z-axis is the vertically upward direction. In addition, in each drawing including FIGS. 1 and 2, only components necessary for explanation are shown, and descriptions of general components may be omitted.

  The bonding system 1 according to this embodiment shown in FIG. 1 forms a superposed substrate T by bonding a first substrate W1 and a second substrate W2 (see FIG. 2).

  The first substrate W1 is a substrate in which a plurality of electronic circuits are formed on a semiconductor substrate such as a silicon wafer or a compound semiconductor wafer. The second substrate W2 is, for example, a bare wafer on which no electronic circuit is formed. The first substrate W1 and the second substrate W2 have substantially the same diameter.

  An electronic circuit may be formed on the second substrate W2. Further, as the above-described compound semiconductor wafer, for example, a wafer containing gallium arsenide, silicon carbide, gallium nitride, indium phosphide, or the like can be used, but is not limited thereto.

  Hereinafter, the first substrate W1 may be referred to as “upper wafer W1”, the second substrate W2 may be referred to as “lower wafer W2”, and the superposed substrate T may be referred to as “superimposed wafer T”.

  In the following description, as shown in FIG. 2, the plate surface of the upper wafer W1 that is bonded to the lower wafer W2 is referred to as “bonded surface W1j”, and is opposite to the bonded surface W1j. The plate surface is described as “non-bonding surface W1n”. Of the plate surfaces of the lower wafer W2, the plate surface on the side bonded to the upper wafer W1 is described as “bonded surface W2j”, and the plate surface opposite to the bonded surface W2j is referred to as “non-bonded surface W2n”. Describe.

  As shown in FIG. 1, the joining system 1 includes a carry-in / out station 2 and a processing station 3. The loading / unloading station 2 and the processing station 3 are arranged in the order of the loading / unloading station 2 and the processing station 3 along the positive direction of the X axis. Further, the carry-in / out station 2 and the processing station 3 are integrally connected.

  The carry-in / out station 2 includes a mounting table 10 and a transfer area 20. The mounting table 10 includes a plurality of mounting plates 11. On each mounting plate 11, cassettes C1, C2, and C3 for storing a plurality of (for example, 25) substrates in a horizontal state are mounted. The cassette C1 is a cassette that accommodates the upper wafer W1, the cassette C2 is a cassette that accommodates the lower wafer W2, and the cassette C3 is a cassette that accommodates the superposed wafer T.

  The conveyance area 20 is arranged adjacent to the X-axis positive direction side of the mounting table 10. In the transport region 20, a transport path 21 extending in the Y-axis direction and a transport device 22 movable along the transport path 21 are provided. The transfer device 22 is also movable in the X-axis direction and can be swung around the Z-axis, and includes a cassette C1 to C3 mounted on the mounting plate 11 and a third processing block G3 of the processing station 3 described later. In the meantime, the upper wafer W1, the lower wafer W2, and the superposed wafer T are transported.

  Note that the number of cassettes C1 to C3 mounted on the mounting plate 11 is not limited to the illustrated one. In addition to the cassettes C1, C2, and C3, the placement plate 11 may be loaded with a cassette or the like for collecting a substrate having a problem.

  The processing station 3 is provided with a plurality of, for example, three processing blocks G1, G2, G3 provided with various devices. For example, the first processing block G1 is provided on the front side of the processing station 3 (Y-axis negative direction side in FIG. 1), and the second side is disposed on the back side of the processing station 3 (Y-axis positive direction side in FIG. 1). A processing block G2 is provided. A third processing block G3 is provided on the loading / unloading station 2 side of the processing station 3 (X-axis negative direction side in FIG. 1).

  In the first processing block G1, a surface modification device 30, a preheating device 31, and a pressurizing device 32 are arranged. The surface modification device 30 modifies the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2. Specifically, the surface modification device 30 cuts the SiO2 bond at the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 to form single-bonded SiO, so that the bonding can be easily performed thereafter. The surfaces W1j and W2j are modified.

  In the surface modification device 30, for example, the oxygen gas that is the processing gas is excited to be turned into plasma and ionized under reduced pressure. The oxygen ions are irradiated onto the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2, whereby the bonding surfaces W1j and W2j are plasma-treated and modified.

  The preheating device 31 raises the temperature of the superposed wafer T joined by a joining device described later to a preheating temperature. Further, the pressurizing device 32 raises the temperature of the superposed wafer T from a preheating temperature to a predetermined temperature, for example, and pressurizes the superposed wafer T at a predetermined temperature. Thereby, it can suppress that a bubble (void) generate | occur | produces between the upper wafer W1 and the lower wafer W2 in the superposition | polymerization wafer T, and wafer W1, W2 can be joined appropriately, but this is mentioned later. . Moreover, the structure of the preheating apparatus 31 and the pressurization apparatus 32 is also mentioned later.

  The arrangement positions of the preheating device 31 and the pressurizing device 32 shown in FIG. 1 are examples and are not limited. That is, for example, the preheating device 31 and the pressurizing device 32 may be arranged in the second processing block G2 or the third processing block G3. Furthermore, for example, a new station is provided between the position of the processing station 3 on the positive side of the X axis and between the loading / unloading station 2 and the processing station 3, and the preheating device 31 and the pressurizing device 32 are arranged in the new station. You may make it do.

  In the second processing block G2, a surface hydrophilizing device 40 and a joining device 41 are arranged. The surface hydrophilizing device 40 hydrophilizes the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 with a hydrophilic treatment liquid such as pure water, and cleans the bonding surfaces W1j and W2j. In the surface hydrophilizing device 40, for example, pure water is supplied onto the upper wafer W1 or the lower wafer W2 while rotating the upper wafer W1 or the lower wafer W2 held by the spin chuck. Thereby, the pure water supplied onto the upper wafer W1 or the lower wafer W2 diffuses on the bonding surfaces W1j and W2j of the upper wafer W1 or the lower wafer W2, and the bonding surfaces W1j and W2j are hydrophilized.

  The bonding apparatus 41 bonds the hydrophilicized upper wafer W1 and lower wafer W2 by intermolecular force. The configuration of the joining device 41 will be described later.

  In the third processing block G3, transition devices 50 for the upper wafer W1, the lower wafer W2, and the overlapped wafer T are provided, for example, in two upper and lower stages.

  A transfer area 60 is formed in an area surrounded by the first processing block G1 to the third processing block G3. A transport device 61 is disposed in the transport area 60. The transfer device 61 has a transfer arm that can move around the vertical direction, the horizontal direction, and the vertical axis, for example. The transfer device 61 moves in the transfer region 60, and transfers the upper wafer W1 and the lower wafer W2 to predetermined devices in the first processing block G1, the second processing block G2, and the third processing block G3 adjacent to the transfer region 60. And the superposed wafer T is transported.

  In addition, as illustrated in FIG. 1, the bonding system 1 includes a control device 70. The control device 70 controls the operation of the bonding system 1. The control device 70 is a computer, for example, and includes a control unit and a storage unit (not shown). The storage unit stores a program for controlling various processes such as a bonding process, a pre-heat treatment, and a pressure process, and data used in the various processes. The control unit controls the operation of the bonding system 1 by reading and executing a program or the like stored in the storage unit.

  Note that such a program may be recorded on a computer-readable recording medium and may be installed in the storage unit of the control device 70 from the recording medium. Examples of the computer-readable recording medium include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical disk (MO), and a memory card.

<2. Structure of joining device>
First, the structure of the joining apparatus 41 is demonstrated with reference to FIGS. FIG. 3 is a schematic plan view showing the configuration of the bonding apparatus 41, and FIG. 4 is a schematic side view thereof. FIG. 5 is a schematic side view showing the configuration of the position adjusting mechanism. 6 is a schematic plan view showing the configuration of the reversing mechanism, FIGS. 7 and 8 are schematic side views thereof, and FIG. 9 is a schematic side view showing the configurations of the holding arm and the holding member. . FIG. 10 is a schematic side view showing the internal configuration of the bonding apparatus 41.

  As shown in FIG. 3, the bonding apparatus 41 includes a processing container 190 that can seal the inside. A loading / unloading port 191 for the upper wafer W1, the lower wafer W2, and the overlapped wafer T is formed on the side surface of the processing container 190 on the transfer area 60 side, and an opening / closing shutter 192 is provided at the loading / unloading port 191.

  The inside of the processing container 190 is divided into a transport area T1 and a processing area T2 by an inner wall 193. The loading / unloading port 191 described above is formed on the side surface of the processing container 190 in the transfer region T1. In addition, a carry-in / out port 194 for the upper wafer W1, the lower wafer W2, and the overlapped wafer T is also formed on the inner wall 193.

  A transition 200 for temporarily placing the upper wafer W1, the lower wafer W2, and the superposed wafer T is provided on the negative side of the transfer region T1 in the Y axis direction. The transition 200 is formed, for example, in two stages, and any two of the upper wafer W1, the lower wafer W2, and the superposed wafer T can be placed simultaneously.

  A transport mechanism 201 is provided in the transport region T1. The transport mechanism 201 has, for example, a transport arm that can move around the vertical direction, the horizontal direction, and the vertical axis. Then, the transport mechanism 201 transports the upper wafer W1, the lower wafer W2, and the overlapped wafer T within the transport region T1 or between the transport region T1 and the processing region T2.

  A position adjustment mechanism 210 that adjusts the horizontal orientation of the upper wafer W1 and the lower wafer W2 is provided on the Y axis positive direction side of the transfer region T1. As shown in FIG. 5, the position adjustment mechanism 210 detects the positions of the base 211, the holding unit 212 that holds and rotates the upper wafer W1 and the lower wafer W2, and the notch portions of the upper wafer W1 and the lower wafer W2. And a detecting unit 213 for performing

  In the position adjustment mechanism 210, the position of the notch portions of the upper wafer W1 and the lower wafer W2 is detected by the detection unit 213 while rotating the upper wafer W1 and the lower wafer W2 held by the holding unit 212. The horizontal direction of the upper wafer W1 and the lower wafer W2 is adjusted by adjusting the position of the portion.

  In addition, a reversing mechanism 220 that reverses the front and back surfaces of the upper wafer W1 is provided in the transfer region T1. The reversing mechanism 220 has a holding arm 221 that holds the upper wafer W1 as shown in FIGS.

  The holding arm 221 extends in the horizontal direction. The holding arm 221 is provided with holding members 222 for holding the upper wafer W1, for example, at four locations. As shown in FIG. 9, the holding member 222 is configured to be movable in the horizontal direction with respect to the holding arm 221. A cutout 223 for holding the peripheral edge of the upper wafer W1 is formed on the side surface of the holding member 222. These holding members 222 can sandwich and hold the upper wafer W1.

  As shown in FIGS. 6 to 8, the holding arm 221 is supported by a first driving unit 224 provided with, for example, a motor. The holding arm 221 can be rotated around the horizontal axis by the first driving unit 224. The holding arm 221 is rotatable about the first driving unit 224 and is movable in the horizontal direction.

  Below the first drive unit 224, a second drive unit 225 including, for example, a motor is provided. By the second drive unit 225, the first drive unit 224 is movable in the vertical direction along the support pillar 226 extending in the vertical direction.

  As described above, the upper wafer W1 held by the holding member 222 can be rotated about the horizontal axis by the first driving unit 224 and the second driving unit 225, and can be moved in the vertical direction and the horizontal direction. it can. Further, the upper wafer W <b> 1 held by the holding member 222 can rotate around the first driving unit 224 and move from the position adjusting mechanism 210 to the upper chuck 230 described later.

  As shown in FIG. 4, an upper chuck 230 and a lower chuck 231 are provided in the processing region T2. The upper chuck 230 sucks and holds the upper wafer W1 from above. The lower chuck 231 is provided below the upper chuck 230 and sucks and holds the lower wafer W2 from below.

  As shown in FIG. 4, the upper chuck 230 is supported by a support member 280 provided on the ceiling surface of the processing container 190.

  The support member 280 is provided with an upper imaging unit 281 (see FIG. 10) that images the bonding surface W2j of the lower wafer W2 held by the lower chuck 231. The upper imaging unit 281 is provided adjacent to the upper chuck 230.

  As shown in FIGS. 3, 4, and 10, the lower chuck 231 is supported by a first lower chuck moving unit 290 provided below the lower chuck 231. The first lower chuck moving unit 290 moves the lower chuck 231 in the horizontal direction (Y-axis direction) as will be described later. The first lower chuck moving unit 290 is configured to be able to move the lower chuck 231 in the vertical direction and to rotate about the vertical axis.

  The first lower chuck moving unit 290 is provided with a lower imaging unit 291 that images the bonding surface W1j of the upper wafer W1 held by the upper chuck 230. The lower imaging unit 291 is provided adjacent to the lower chuck 231.

  As shown in FIGS. 3, 4, and 10, the first lower chuck moving unit 290 is provided on the lower surface side of the first lower chuck moving unit 290 and extends in the horizontal direction (Y-axis direction). 295,295. The first lower chuck moving unit 290 is configured to be movable along the rail 295.

  The pair of rails 295 and 295 are provided in the second lower chuck moving unit 296. The second lower chuck moving unit 296 is provided on the lower surface side of the second lower chuck moving unit 296 and attached to a pair of rails 297 and 297 extending in the horizontal direction (X-axis direction). The second lower chuck moving unit 296 is configured to be movable along the rail 297, that is, to move the lower chuck 231 in the horizontal direction (X-axis direction). The pair of rails 297 and 297 are provided on a mounting table 298 provided on the bottom surface of the processing container 190.

  Next, the configuration of the upper chuck 230 and the lower chuck 231 will be described with reference to FIGS. FIG. 11 is a schematic side view showing configurations of the upper chuck 230 and the lower chuck 231. FIG. 12 is a schematic plan view when the upper chuck 230 is viewed from below, and FIG. 13 is a schematic plan view when the lower chuck 231 is viewed from above.

  As shown in FIG. 11, the upper chuck 230 is divided into a plurality of, for example, three regions 230a, 230b, and 230c. These regions 230a, 230b, and 230c are provided in this order from the central portion of the upper chuck 230 toward the peripheral portion (outer peripheral portion), as shown in FIG. The region 230a has a circular shape in plan view, and the regions 230b and 230c have an annular shape in plan view.

  As shown in FIG. 11, suction tubes 240a, 240b, and 240c for sucking and holding the upper wafer W1 are provided in each of the regions 230a, 230b, and 230c, respectively. Different vacuum pumps 241a, 241b, 241c are connected to the suction tubes 240a, 240b, 240c, respectively. Thus, the upper chuck 230 is configured to be able to set the evacuation of the upper wafer W1 for each of the regions 230a, 230b, and 230c.

  A through hole 243 that penetrates the upper chuck 230 in the thickness direction is formed at the center of the upper chuck 230. The central portion of the upper chuck 230 corresponds to the central portion W1a of the upper wafer W1 attracted and held by the upper chuck 230. And the pushing pin 251 of the pushing member 250 mentioned later is penetrated by the through-hole 243. As shown in FIG.

  On the upper surface of the upper chuck 230, a pushing member 250 that pushes the central portion of the upper wafer W1 is provided. The pushing member 250 has a cylinder structure and includes a pushing pin 251 and an outer cylinder 252 that serves as a guide when the pushing pin 251 moves up and down. The push pin 251 can be moved up and down in the vertical direction through the through hole 243 by, for example, a drive unit (not shown) incorporating a motor. The pushing member 250 can press the center portion W1a of the upper wafer W1 and the center portion W2a of the lower wafer W2 in contact with each other when the upper wafer W1 and the lower wafer W2, which will be described later, are bonded.

  As shown in FIG. 13, the lower chuck 231 is divided into a plurality of, for example, two regions 231a and 231b. These regions 231a and 231b are provided in this order from the center of the lower chuck 231 toward the peripheral edge. The region 231a has a circular shape in plan view, and the region 231b has an annular shape in plan view.

  As shown in FIG. 11, suction tubes 260a and 260b for sucking and holding the lower wafer W2 are provided in each of the regions 231a and 231b, respectively. Different vacuum pumps 261a and 261b are connected to the suction tubes 260a and 260b, respectively. Thus, the lower chuck 231 is configured to be able to set the evacuation of the lower wafer W2 for each of the regions 231a and 231b.

  Stopper members 263 that prevent the upper wafer W1, the lower wafer W2, and the overlapped wafer T from jumping out from the lower chuck 231 or sliding down are provided at a plurality of, for example, five locations on the peripheral edge of the lower chuck 231. .

<3. Wafer Position Adjustment and Bonding Operation in Bonding Apparatus>
Next, the position adjustment of the upper wafer W1 and the lower wafer W2 and the bonding operation of the upper wafer W1 and the lower wafer W2 in the bonding apparatus 41 configured as described above will be specifically described. 14A to 14H are operation explanatory views of the joining device 41. FIG.

  Here, it is assumed that the upper wafer W1 and the lower wafer W2 shown in FIGS. 14A to 14H are subjected to a modification process and a hydrophilization process on the bonding surfaces W1j and W2j, respectively. Further, it is assumed that the non-bonding surface W1n of the upper wafer W1 is held by suction on the upper chuck 230, and the non-bonding surface W2n of the lower wafer W2 is held by suction on the lower chuck 231.

  Then, the horizontal position adjustment of the upper wafer W1 held by the upper chuck 230 and the lower wafer W2 held by the lower chuck 231 is performed.

  As shown in FIG. 14A, a plurality of predetermined reference points A1 to A3, for example, three reference points A1 to A3 are formed on the bonding surface W1j of the upper wafer W1, and similarly, predetermined on the bonding surface W2j of the lower wafer W2. A plurality of, for example, three reference points B1 to B3 are formed. As these reference points A1 to A3 and B1 to B3, for example, predetermined patterns formed on the upper wafer W1 and the lower wafer W2 are used, respectively. The number of reference points can be arbitrarily set.

  First, as shown in FIG. 14A, the horizontal positions of the upper imaging unit 281 and the lower imaging unit 291 are adjusted. Specifically, the lower chuck 231 is moved in the horizontal direction by the first lower chuck moving unit 290 and the second lower chuck moving unit 296 so that the lower imaging unit 291 is positioned substantially below the upper imaging unit 281. Then, the target X common to the upper imaging unit 281 and the lower imaging unit 291 is confirmed, and the horizontal position of the lower imaging unit 291 is fine so that the horizontal positions of the upper imaging unit 281 and the lower imaging unit 291 match. Adjusted.

  Next, as shown in FIG. 14B, after the lower chuck 231 is moved vertically upward by the first lower chuck moving unit 290, the horizontal positions of the upper chuck 230 and the lower chuck 231 are adjusted.

  Specifically, the reference point B1 of the bonding surface W2j of the lower wafer W2 using the upper imaging unit 281 while moving the lower chuck 231 in the horizontal direction by the first lower chuck moving unit 290 and the second lower chuck moving unit 296. To B3 are sequentially imaged. At the same time, while moving the lower chuck 231 in the horizontal direction, the lower imaging unit 291 is used to sequentially image the reference points A1 to A3 of the bonding surface W1j of the upper wafer W1. 14B shows a state in which the upper imaging unit 281 images the reference point B1 of the lower wafer W2, and the lower imaging unit 291 images the reference point A1 of the upper wafer W1.

  The captured image data is output to the control device 70. In the control device 70, based on the image data picked up by the upper image pickup unit 281 and the image data picked up by the lower image pickup unit 291, the reference points A1 to A3 of the upper wafer W1 and the reference points B1 to B3 of the lower wafer W2 The horizontal position of the lower chuck 231 is adjusted by the first and second lower chuck moving parts 290 and 296 so that the two match each other. Thus, the horizontal positions of the upper chuck 230 and the lower chuck 231 are adjusted, and the horizontal positions of the upper wafer W1 and the lower wafer W2 are adjusted.

  Next, as shown in FIG. 14C, the lower chuck 231 is moved vertically upward by the first lower chuck moving unit 290, and the vertical positions of the upper chuck 230 and the lower chuck 231 are adjusted. The vertical position of the upper wafer W1 held by the lower wafer W2 and the lower wafer W2 held by the lower chuck 231 is adjusted. At this time, the interval between the bonding surface W2j of the lower wafer W2 and the bonding surface W1j of the upper wafer W1 is a predetermined distance, for example, 80 μm to 200 μm.

  With this configuration, the horizontal position and the vertical position can be adjusted with high accuracy with respect to the upper wafer W1 and the lower wafer W2.

  FIG. 14D shows a state of the upper chuck 230, the upper wafer W1, the lower chuck 231 and the lower wafer W2 after the adjustment of the horizontal position and the vertical position is completed. As shown in FIG. 14D, the upper wafer W1 is evacuated and held in all the regions 230a, 230b, and 230c of the upper chuck 230, and the lower wafer W2 is also evacuated in all the regions 231a and 231b of the lower chuck 231. Is held.

  Next, a bonding process is performed in which the upper wafer W1 and the lower wafer W2 are bonded by an intermolecular force under normal temperature and normal pressure. Here, the normal temperature is a temperature at a location where the bonding apparatus 41 is installed, and is, for example, a temperature range of 25 ° C. to 70 ° C., but is not limited thereto. Moreover, although normal pressure is atmospheric pressure, for example, it does not need to be exactly the same as atmospheric pressure, and may include, for example, a pressure range of ± 10 kPa with respect to atmospheric pressure.

  Specifically, in the bonding process, the operation of the vacuum pump 241a is stopped, and the evacuation of the upper wafer W1 from the suction tube 240a in the region 230a is stopped as shown in FIG. 14E. At this time, in the areas 230b and 230c, the upper wafer W1 is evacuated and held by suction. Thereafter, the push pin 251 of the push member 250 is lowered to lower the upper wafer W1 while pressing the central portion W1a of the upper wafer W1. At this time, a load such as 200 g is applied to the push pin 251 so that the push pin 251 moves by 70 μm in the absence of the upper wafer W1. Then, the central portion W1a of the upper wafer W1 and the central portion W2a of the lower wafer W2 are brought into contact with each other and pressed by the pushing member 250.

  As a result, the bonding starts between the pressed center portion W1a of the upper wafer W1 and the center portion W2a of the lower wafer W2 (thick line portion in FIG. 14E). That is, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are respectively modified, first, van der Waals force (intermolecular force) is generated between the bonding surfaces W1j and W2j, and the bonding surface W1j and W2j are joined together. Furthermore, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are each made hydrophilic, the hydrophilic groups between the bonding surfaces W1j and W2j are hydrogen-bonded, and the bonding surfaces W1j and W2j are firmly bonded to each other. Is done.

  Thereafter, as shown in FIG. 14F, in a state where the central portion W1a of the upper wafer W1 and the central portion W2a of the lower wafer W2 are pressed by the pushing member 250, the operation of the vacuum pump 241b is stopped, and the suction tube in the region 230b The evacuation of the upper wafer W1 from 240b is stopped.

  As a result, the upper wafer W1 held in the region 230b falls on the lower wafer W2. Thereafter, the operation of the vacuum pump 241c is stopped, and the evacuation of the upper wafer W1 from the suction tube 240c in the region 230c is stopped. In this way, evacuation of the upper wafer W1 is stopped in stages from the central portion W1a of the upper wafer W1 toward the peripheral edge W1b, and the upper wafer W1 drops and contacts the lower wafer W2 in stages. And the joining by the van der Waals force and hydrogen bond between the joint surfaces W1j and W2j described above gradually expands from the central portion W1a toward the peripheral portion W1b.

  Thus, as shown in FIG. 14G, the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 come into contact with each other, and the upper wafer W1 and the lower wafer W2 are bonded.

  Thereafter, as shown in FIG. 14H, the pushing member 250 is raised to the upper chuck 230. Further, evacuation of the lower wafer W2 from the suction tubes 260a and 260b in the lower chuck 231 is stopped, and the suction holding of the lower wafer W2 by the lower chuck 231 is released. Thereby, the joining process in the joining apparatus 41 is complete | finished.

  By the way, when the upper wafer W1 and the lower wafer W2 are bonded at room temperature and normal pressure as described above, depending on the bonding state of the upper wafer W1 and the lower wafer W2 in the bonding apparatus 41, bubbles may be generated between the bonded wafers W1 and W2. May occur.

  That is, in the bonding apparatus 41 of the bonding system 1, as described above, the upper wafer W1 and the lower wafer W2 are bonded in a stepwise manner from the central portions W1a and W2a toward the peripheral portions W1b and W2b.

  Therefore, the air existing between the upper wafer W1 and the lower wafer W2 is pushed out toward the peripheral edge portions W1b and W2b with the stepwise joining of the upper and lower wafers W1 and W2, and finally the peripheral edge portion W1b. , Discharged outward from the W2b side. However, for example, if the peripheral edge portions W1b, W2b are brought into contact and joined before the air is discharged outward, the air may remain as bubbles between the upper wafer W1 and the lower wafer W2.

  Therefore, in the bonding system 1 according to this embodiment, the superposed wafer T is heated to a predetermined temperature, and a pressurizing device 32 that pressurizes the superposed wafer T at a predetermined temperature is provided. Thereby, generation | occurrence | production of the bubble between the wafers W1 and W2 in the superposition | polymerization wafer T can be suppressed, and also the joining strength (bonding force) of the upper wafer W1 and the lower wafer W2 can be improved. W2 can be appropriately joined together.

  Furthermore, in the joining system 1 according to the present embodiment, the preheating device 31 that raises the temperature of the superposed wafer T to the preheating temperature is provided before pressurization by the pressurizing device 32. As a result, the superposed wafer T joined by the joining device 41 can be heated to the preheating temperature by the preheating device 31 and then pressurized by the pressurizing device 32. Thus, the throughput of the process can be improved by raising the temperature of the superposed wafer T in advance by the preheating device 31 different from the pressurizing device 32.

<4. Configuration of preheating device>
Hereinafter, the preheating device 31 will be described with reference to FIG. FIG. 15 is a schematic side view showing the configuration of the preheating device 31.

  As shown in FIG. 15, the preheating device 31 includes an upper flat plate portion 301, a lower flat plate portion 401, and a chamber 501. Between the upper flat plate portion 301 and the lower flat plate portion 401, the superposed wafer T is transported and placed on the lower flat plate portion 401.

  Specifically, the upper flat plate portion 301 is positioned above the overlapped wafer T. On the other hand, the lower flat plate portion 401 is disposed opposite to the upper flat plate portion 301 below the upper flat plate portion 301 and is positioned below the overlapped wafer T. The upper flat plate portion 301 and the lower flat plate portion 401 have a substantially disk shape having a larger diameter than the superposed wafer T.

  The chamber 501 is a processing container whose inside can be sealed, and accommodates the upper flat plate portion 301, the lower flat plate portion 401, and the like. In addition, although illustration is abbreviate | omitted, opening is provided in the side wall of the chamber 501, and the superposition | polymerization wafer T is carried in / out from this opening.

  The upper flat plate portion 301 and the lower flat plate portion 401 contain heating mechanisms 311 and 411, respectively. The heating mechanism 311 heats the upper flat plate portion 301 to heat the overlapped wafer T from above the overlapped wafer T, specifically, from the upper wafer W1 side. The heating mechanism 411 heats the lower flat plate portion 401 and heats the overlapped wafer T on the lower flat plate portion 401 from below, specifically from the lower wafer W2 side.

  The superposed wafer T of the preheating device 31 is subjected to preheat treatment for raising the temperature to a preheating temperature by the heating mechanism 311 of the upper flat plate portion 301 and the heating mechanism 411 of the lower flat plate portion 401. Here, the preheating temperature is set to, for example, a temperature higher than normal temperature and lower than a predetermined temperature when pressurizing the superposed wafer T by the pressurizing device 32. In addition, although the preheating temperature in this embodiment is set, for example to 200 to 300 degreeC, this is an illustration and is not limited.

  Further, the lower flat plate portion 401 is provided with a plurality of support pins 420 on the placement surface 413 on which the superposed wafer T is placed. The support pin 420 is configured to be movable up and down, and can protrude from the placement surface 413 of the lower flat plate portion 401. When the superposed wafer T is carried into the preheating device 31, the superposed wafer T is placed on the support pins 420 protruding from the placement surface 413, and then the support pins 420 are lowered so that the superposed wafer T is placed. It is placed on the placement surface 413.

  The upper flat plate portion 301 and the lower flat plate portion 401 are supported at a predetermined height by spacers 321 and 421, respectively.

  Note that the preheating device 31 may include an elevating mechanism that elevates and lowers the upper flat plate portion 301 in the Z-axis direction instead of the spacer 321 or in addition to the spacer 321. In this case, the upper flat plate portion 301 can be brought close to or in contact with the superposed wafer T by the lifting mechanism, and the superposed wafer T can be efficiently heated to the preheating temperature. In the above-described lifting mechanism, the upper flat plate portion 301 is raised and lowered. However, the present invention is not limited to this, and a configuration in which one or both of the upper flat plate portion 301 and the lower flat plate portion 401 are raised and lowered may be used.

  In addition, in the preheating apparatus 31 which concerns on this embodiment, it is preferable that the temperature of the upper flat plate part 301 and the lower flat plate part 401 is the same. Thereby, in the superposed wafer T, the amount of expansion / contraction of the upper wafer W1 and the lower wafer W2 can be made substantially the same, and the occurrence of warpage or the like can be suppressed. In the present specification, “the same” temperature does not need to be completely the same, and the temperature may be regarded as “the same” if the temperature difference between the two is within an allowable range.

<5. Configuration of pressurizer>
Next, the pressurizing device 32 will be described with reference to FIG. FIG. 16 is a schematic side view showing the configuration of the pressure device 32.

  As shown in FIG. 16, the pressing device 32 includes a first flat plate portion 601 and a second flat plate portion 701. The overlapped wafer T is transported between the first flat plate portion 601 and the second flat plate portion 701 and is placed and held on the second flat plate portion 701.

  Specifically, the first flat plate portion 601 is positioned above the overlapped wafer T. On the other hand, the second flat plate portion 701 is disposed below the first flat plate portion 601 so as to face the first flat plate portion 601 and positioned below the overlapped wafer T. The first flat plate portion 601 and the second flat plate portion 701 have a substantially disk shape larger in diameter than the superposed wafer T.

  As the second flat plate portion 701 described above, a chuck capable of adsorbing and holding the overlapped wafer T can be used. Specifically, for example, the second flat plate portion 701 is an electrostatic chuck (ESC), and holds the superposed wafer T by electrostatic adsorption.

  Here, the configuration of the second flat plate portion 701 will be described with reference to FIG. FIG. 17 is a schematic side view showing the configuration of the second flat plate portion 701.

  As shown in FIG. 17, the second flat plate portion 701 is a Johnson-Rahbek type electrostatic chuck and includes an electrostatic attraction portion 711.

  The electrostatic attraction unit 711 includes a plurality of internal electrodes 711a, and uses the electrostatic force generated on the holding surface 713 by the internal electrodes 711a to adsorb the overlapped wafer T from below.

  As described above, by using the electrostatic chuck as the second flat plate portion 701, for example, the superposed wafer T can be held even under reduced pressure (vacuum). In other words, since the electrostatic chuck does not decrease the adsorption force even under a reduced pressure (vacuum) environment, the superposed wafer T can be reliably held.

  Further, the second flat plate part 701 includes a vacuum suction part 712 in addition to the electrostatic suction part 711. As shown in FIG. 17, the vacuum suction part 712 includes a suction tube 712a and a plurality of through holes 712b communicating from the holding surface 713 to the suction tube 712a. A vacuum pump 714 is connected to the suction pipe 712a.

  The vacuum suction unit 712 uses the negative pressure generated by the suction of the vacuum pump 714 to hold the superposed wafer T by adsorbing the superposed wafer T. The second flat plate portion 701 is formed of ceramics such as aluminum nitride.

  In the above description, the second flat plate portion 701 is configured to include both the electrostatic chuck 711 and the vacuum chuck 712, but may include either one. Specifically, for example, in the pressurization process of the superposed wafer T described later, when the pressure is applied under reduced pressure, the suction force by the vacuum suction unit 712 is reduced, and therefore it is preferable to include the electrostatic suction unit 711. . On the other hand, for example, when the superposed wafer T is not pressurized under reduced pressure, it may be either one of the electrostatic adsorption unit 711 and the vacuum adsorption unit 712.

  As shown in FIG. 16, the first flat plate portion 601 includes a first heating mechanism 617, and the second flat plate portion 701 includes a second heating mechanism 717. The first heating mechanism 617 heats the first flat plate portion 601 to heat the overlapped wafer T from above, specifically from the upper wafer W1 side. The second heating mechanism 717 heats the second flat plate portion 701 and heats the overlapped wafer T held by the second flat plate portion 701 from below, specifically from the lower wafer W2 side.

  The superposed wafer T of the pressurizing device 32 is heated to a predetermined temperature by the first heating mechanism 617 of the first flat plate portion 601 and the second heating mechanism 717 of the second flat plate portion 701. Here, the predetermined temperature is set to a temperature higher than room temperature. Specifically, the predetermined temperature is a temperature at which the bonding surfaces W1j and W2j of the superposed wafer T can be varied. More specifically, the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are relatively moved. The temperature is such that In addition, although the predetermined temperature in this embodiment is set, for example to 300 to 500 degreeC, this is an illustration and is not limited.

  Moreover, in the pressurization apparatus 32 which concerns on this embodiment, it is preferable that the temperature of the 1st flat plate part 601 and the 2nd flat plate part 701 is the same. Thereby, in the superposed wafer T, the amount of expansion / contraction of the upper wafer W1 and the lower wafer W2 can be made substantially the same, and the occurrence of warpage or the like can be suppressed.

  The second flat plate portion 701 is provided with a plurality of support pins (an example of a support portion) 720 on the surface facing the overlapped wafer T, that is, the holding surface 713. The support pin 720 is configured to be movable up and down, and can protrude from the holding surface 713 of the second flat plate portion 701. Then, when the superposed wafer T is carried into the pressure device 32, it is placed on the support pins 720 protruding from the holding surface 713, and then the support pins 720 are lowered so that the superposed wafer T is held. It is placed on the surface 713 and held by suction.

  At this time, it is assumed that both the first heating mechanism 617 and the second heating mechanism 717 are operating. Therefore, for example, by adjusting the speed at which the support pins 720 are lowered, the speed of temperature rise in the superposed wafer T can be appropriately controlled. This will be described later.

  Stopper members 730 for preventing the overlapped wafer T from jumping out from the second flat plate portion 701 or sliding down are provided at a plurality of, for example, five locations on the peripheral edge of the second flat plate portion 701. The second flat plate portion 701 is supported at a predetermined height by the spacer 704.

  Further, the pressure device 32 includes a base member 801 and a pressure mechanism 802. The base member 801 is attached to the ceiling surface inside the first chamber portion 811 described later.

  The pressurizing mechanism 802 pressurizes the overlapped wafer T by relatively moving the first flat plate portion 601 and the second flat plate portion 701. Specifically, the pressurizing mechanism 802 presses the superposed wafer T by bringing the first flat plate portion 601 into contact with the superposed wafer T from above by moving it vertically downward. The pressurizing mechanism 802 includes a pressure vessel 803, a gas supply pipe 804, and a gas supply source 805.

  The pressure vessel 803 is made of, for example, a stainless steel bellows that can expand and contract in the vertical direction. The lower end portion of the pressure vessel 803 is fixed to the upper surface of the first flat plate portion 601, and the upper end portion is fixed to the lower surface of the base member 801.

  One end of the gas supply pipe 804 is connected to the pressure vessel 803 via the base member 801 and a first chamber portion 811 described later, and the other end is connected to the gas supply source 805.

  In the pressure vessel 803, the gas is supplied from the gas supply source 805 to the inside of the pressure vessel 803 through the gas supply pipe 804, whereby the pressure vessel 803 is extended and the first flat plate portion 601 is lowered. Thereby, the 1st flat plate part 601 contacts with the superposition | polymerization wafer T, and is pressurized. The pressure applied to the superposed wafer T is adjusted by adjusting the pressure of the gas supplied to the pressure vessel 803. In addition, although the applied pressure to the superposition | polymerization wafer T in this embodiment is set to 0.5 Mpa-10 Mpa, for example, this is an illustration and is not limited.

  Further, the pressurizing device 32 includes a chamber 810 and a decompression unit 820. The chamber 810 is a processing container whose inside can be sealed, and includes a first chamber portion 811 and a second chamber portion 812.

  The first chamber portion 811 is a bottomed cylindrical container having an open lower portion, and the first flat plate portion 601 and the pressure vessel 803 are accommodated therein. The second chamber portion 812 is a bottomed cylindrical container having an open top, and houses a second flat plate portion 701, a spacer 704, and the like.

  The first chamber portion 811 is configured to be vertically movable by a lifting mechanism (not shown) such as an air cylinder. The first chamber part 811 is lowered by this lifting mechanism and brought into contact with the second chamber part 812, thereby forming a sealed space inside the chamber 810. Note that a sealing member 813 for ensuring the confidentiality of the chamber 810 is provided on the contact surface of the first chamber portion 811 with the second chamber portion 812. For example, an O-ring is used as the seal member 813.

  The decompression unit 820 is provided, for example, below the second chamber unit 812, and decompresses the inside of the chamber 810. The decompression unit 820 includes an intake pipe 821 for taking in the atmosphere in the chamber 810 and an intake device 822 such as a vacuum pump connected to the intake pipe 821.

  The pressurizing device 32 is provided inside a processing container (not shown), and an FFU (Fan Filter Unit; not shown) is provided on the ceiling of the processing container. The FFU forms a down flow in a processing container (not shown).

<6. Specific operation of joining system>
Next, a specific operation of the joining system 1 configured as described above will be described with reference to FIG. FIG. 18 is a flowchart illustrating a part of a processing procedure of processing executed by the joining system 1. Note that the various processes shown in FIG. 18 are executed based on control by the control device 70.

  First, a cassette C1 containing a plurality of upper wafers W1, a cassette C2 containing a plurality of lower wafers W2, and an empty cassette C3 are placed on a predetermined placement plate 11 of the carry-in / out station 2. Thereafter, the upper wafer W1 in the cassette C1 is taken out by the transfer device 22 and transferred to the transition device 50 of the third processing block G3 of the processing station 3.

  Next, the upper wafer W1 is transferred by the transfer device 61 to the surface modification device 30 of the first processing block G1. In the surface reforming apparatus 30, oxygen gas, which is a processing gas, is excited and turned into plasma and ionized under a predetermined reduced pressure. The oxygen ion is irradiated onto the bonding surface W1j of the upper wafer W1, and the bonding surface W1j is subjected to plasma processing. Thereby, the joint surface W1j of the upper wafer W1 is modified (step S1).

  Next, the upper wafer W1 is transferred by the transfer device 61 to the surface hydrophilizing device 40 of the second processing block G2. In the surface hydrophilizing device 40, pure water is supplied onto the upper wafer W1 while rotating the upper wafer W1 held by the spin chuck. Then, the supplied pure water diffuses on the bonding surface W1j of the upper wafer W1, and a hydroxyl group (silanol group) adheres to the bonding surface W1j of the upper wafer W1 modified by the surface modifying device 30. W1j is hydrophilized. Further, the bonding surface W1j of the upper wafer W1 is cleaned with the pure water (step S2).

  The processes in steps S1 and S2 described above are also performed on the lower wafer W2. That is, first, the lower wafer W2 in the cassette C2 is taken out by the transfer device 22 and transferred to the transition device 50 of the processing station 3.

  Next, the lower wafer W2 is transferred to the surface modification device 30 by the transfer device 61, and the bonding surface W2j of the lower wafer W2 is modified (step S1). Thereafter, the lower wafer W2 is transferred to the surface hydrophilizing device 40 by the transfer device 61, and the bonding surface W2j of the lower wafer W2 is hydrophilized and the bonding surface W2j is cleaned (step S2).

  Next, the upper wafer W1 and the lower wafer W2 are transferred by the transfer device 61 to the bonding device 41 of the second processing block G2, and a bonding process is performed (step S3). Specifically, the upper wafer W <b> 1 carried into the bonding apparatus 41 is transferred to the position adjustment mechanism 210 by the transfer mechanism 201 through the transition 200. The position adjusting mechanism 210 adjusts the horizontal direction of the upper wafer W1.

  Thereafter, the upper wafer W <b> 1 is delivered from the position adjustment mechanism 210 to the holding arm 221 of the reversing mechanism 220. Subsequently, in the transfer region T1, the front and back surfaces of the upper wafer W1 are reversed by reversing the holding arm 221. That is, the bonding surface W1j of the upper wafer W1 is directed downward.

  Thereafter, the holding arm 221 of the reversing mechanism 220 rotates around the first driving unit 224 and moves below the upper chuck 230. Then, the upper wafer W 1 is delivered from the reversing mechanism 220 to the upper chuck 230. The non-bonding surface W1n of the upper wafer W1 is sucked and held by the upper chuck 230.

  On the other hand, the lower wafer W <b> 2 is also transferred to the bonding apparatus 41 by the transfer device 61. The lower wafer W <b> 2 loaded into the bonding apparatus 41 is transferred to the position adjustment mechanism 210 by the transfer mechanism 201 through the transition 200. The position adjustment mechanism 210 adjusts the horizontal direction of the lower wafer W2.

  Thereafter, the lower wafer W2 is transferred to the lower chuck 231 by the transfer mechanism 201 and is sucked and held by the lower chuck 231. At this time, the non-bonding surface W2n of the lower wafer W2 is sucked and held by the lower chuck 231 so that the bonding surface W2j of the lower wafer W2 faces upward.

  Then, as described above with reference to FIGS. 14A to 14H, the horizontal and vertical position adjustments of the upper wafer W1 held by the upper chuck 230 and the lower wafer W2 held by the lower chuck 231 are performed. Done. Next, as described above, the operations of the vacuum pumps 241a, 241b, 241c and the pushing member 250 are controlled, and the upper wafer W1 and the lower wafer W2 are bonded by intermolecular force.

  Next, the superposed wafer T to which the upper wafer W1 and the lower wafer W2 are bonded is transported to the preheating device 31 by the transport device 61. The superposed wafer T carried into the preheating device 31 is subjected to preheat treatment for raising the temperature to a preheating temperature by the heating mechanism 311 of the upper flat plate portion 301 and the heating mechanism 411 of the lower flat plate portion 401 (step S4). Thus, the throughput of the process can be improved by raising the temperature of the superposed wafer T in advance by the preheating device 31 different from the pressurizing device 32.

  Next, the superposed wafer T heated to the preheating temperature is transferred to the pressurizing device 32 by the transfer device 61. Then, the pressurizing device 32 performs a pressurizing process for raising the temperature of the conveyed superposed wafer T to a predetermined temperature and pressurizing the superposed wafer T at a predetermined temperature (step S5).

  When the pressurizing process is completed, the overlapped wafer T is transferred to the transition device 50 by the transfer device 61 and then transferred to the cassette C3 of the predetermined placement plate 11 by the transfer device 22 of the carry-in / out station 2. Thus, a series of processing ends.

  Next, a specific example of the pressurizing process in step S5 described above will be described in detail with reference to FIGS. 19 to 20C. FIG. 19 is a flowchart showing a processing procedure for pressurizing the overlapped wafer T. 20A to 20C are operation explanatory views of the pressurizing device 32.

  As shown in FIG. 19, the pressurizing device 32 places and supports the superposed wafer T transported by the transport device 61 on the support pins 720 (step S11, see FIG. 20A).

  Next, the pressure device 32 raises the temperature of the superposed wafer T to a predetermined temperature while gradually lowering the support pins 720 (step S12). In addition, the 1st flat plate part 601 and the 2nd flat plate part 701 shall be predetermined temperature by the 1st heating mechanism 617 and the 2nd heating mechanism 717 previously.

  That is, by gradually lowering the support pins 720, the gap between the second flat plate portion 701 and the overlapped wafer T is gradually shortened, and the overlapped wafer T is gradually heated from the preheating temperature to a predetermined temperature.

  Thereby, for example, by adjusting the speed at which the support pins 720 are lowered, the speed of temperature rise in the superposed wafer T can be appropriately controlled. Specifically, for example, compared with the case where the superposed wafer T immediately after the transfer is immediately placed on the holding surface 713 of the second flat plate portion 701, the temperature rise of the superposed wafer T can be prevented, and the superposed wafer T The effect of heat on can be reduced.

  In the above description, the case where the first flat plate portion 601 and the second flat plate portion 701 are at a predetermined temperature in advance when the overlapped wafer T is transported is shown as an example. However, the present invention is not limited to this. . That is, for example, when the overlapped wafer T is transported, the first flat plate portion 601 and the second flat plate portion 701 may be at the preheating temperature. In such a case, the first and second flat plate portions 601 and 701 are heated from the preheating temperature to the predetermined temperature by the first and second heating mechanisms 617 and 717 after the superposed wafer T is transported, whereby the superposed wafer T is The temperature is raised to a predetermined temperature.

  Subsequently, the pressurizing device 32 sucks and holds the overlapped wafer T from below using the second flat plate portion 701 (step S13). Specifically, for example, in the second flat plate portion 701 of the pressurizing device 32, the superposed wafer T is sucked by the vacuum suction portion 712, and then the superposed wafer T is sucked and held by the electrostatic suction portion 711. Note that the suction by the vacuum suction unit 712 may be stopped after the suction of the superposed wafer T by the electrostatic suction unit 711 is completed.

  Thereby, the 2nd flat plate part 701 can adsorb | suck and hold the superposition | polymerization wafer T reliably. That is, the overlapped wafer T bonded by the bonding apparatus 41 may be warped. In such a case, the overlapped wafer T in a warped state is conveyed to the pressurizing apparatus 32. Further, the overlapped wafer T in which the warp has occurred is in a softened state by being heated to a predetermined temperature.

  Therefore, in the pressurizing device 32, as described above, the superposed wafer T is sucked by the vacuum suction unit 712, and the flatness of the superposed wafer T is ensured to some extent. By adsorbing and holding, the second flat plate portion 701 can reliably adsorb and hold the overlapped wafer T.

  Subsequently, the pressurizing device 32 lowers the first chamber portion 811 (step S14). Accordingly, the first chamber portion 811 contacts the second chamber portion 812, and a sealed space is formed in the chamber 810 (see FIG. 20B).

  Here, the temperature of the superposed wafer T is raised to a predetermined temperature and then the first chamber portion 811 is lowered. However, the present invention is not limited to this. That is, for example, the first chamber portion 811 may be lowered before the temperature of the overlapped wafer T is increased (before the process of step S12) or during the process of increasing the temperature of the overlapped wafer T.

  Subsequently, the pressurizing device 32 decompresses the interior of the chamber 810 by sucking the atmosphere in the chamber 810 using the decompression unit 820, specifically, evacuates the chamber 810 (step S15).

  In the above description, the pressurizing device 32 increases the temperature of the overlapped wafer T and then depressurizes the chamber 810. However, the present invention is not limited to this. You may make it make it.

  Subsequently, the pressurizer 32 supplies gas to the pressure vessel 803 of the pressurizing mechanism 802 to lower the first flat plate portion 601 (step S16). Thereby, the 1st flat plate part 601 and the superposition | polymerization wafer T contact.

  In the above description, after reducing the pressure in the chamber 810 in step S15, the first flat plate portion 601 is lowered in step S16. However, the present invention is not limited to this. For example, the process in step S16 is performed before step S15. You may go.

  Subsequently, the pressurizing device 32 further pressurizes the superposed wafer T with the first flat plate portion 601 by further supplying gas to the pressure vessel 803 to bring the inside of the pressure vessel 803 to a desired pressure (step S17, FIG. 20C). reference).

  The superposed wafer T is softened by heating, and when the superposed wafer T is pressed against the superposed wafer T with a desired pressure, air bubbles between the wafers W1 and W2 can be removed, and the upper wafer W1 and the lower wafer W2 are joined. The strength can also be improved.

  Since the overlapped wafer T is adsorbed and held from below by the second flat plate portion 701, for example, the overlapped wafer T is pressed in a state where the warp is extended. Thereby, the applied pressure from the first flat plate portion 601 is transmitted uniformly or substantially uniformly to the overlapped wafer T, and air bubbles between the wafers W1 and W2 can be efficiently removed, and the overlapped wafer T is cracked. Can be prevented from occurring.

  In addition, since the pressure in the chamber 810 is reduced, the bubbles between the wafers W1 and W2 can be more easily removed. Furthermore, since the inside of the chamber 810 is depressurized, oxidation in the superposed wafer T can be suppressed.

  In the above description, the superposed wafer T is pressurized under reduced pressure. However, this is only an example and is not limited. For example, the superposed wafer T may be pressurized under normal pressure. Good. In such a case, it is possible to remove the decompression unit 820 from the pressurizing device 32, and thus the pressurizing device 32 can be simplified and downsized.

  Subsequently, the pressurizing device 32 ends the pressurization to the superposed wafer T by discharging the gas supplied to the pressure vessel 803 from the pressure vessel 803 and lowering the pressure of the pressure vessel 803 (step S18). .

  Here, the pressurization to the overlapped wafer T is terminated when a predetermined condition is satisfied, for example, when a preset predetermined time has elapsed or when a bubble is no longer detected by a detection device (not shown). You may make it do.

  In the pressurizing device 32, for example, it is not necessary to immediately end the pressurization when the predetermined condition described above is satisfied. That is, for example, when predetermined conditions are satisfied, heating by the first and second flat plate portions 601 and 701 is stopped before pressurization is completed. The pressurization may be terminated when the temperature of the superposed wafer T falls below a predetermined temperature range. If comprised in this way, even if pressurization is complete | finished, since the temperature of the superposition | polymerization wafer T has fallen, it can make it difficult to produce the curvature to the superposition | polymerization wafer T. FIG.

  Subsequently, the pressurizing device 32 further discharges the gas from the pressure vessel 803 and raises the first flat plate portion 601 (step S19), and then releases the decompressed state by the decompressing portion 820 to open the chamber 810 to the atmosphere. (Step S20).

  Subsequently, the pressure device 32 turns off the voltage application to the second flat plate portion 701, and the holding of the overlapped wafer T by the second flat plate portion 701 is released (step S21).

  The pressurizing device 32 raises the first chamber portion 811 (step S22), then raises the support pin 720 (step S23), and ends the series of joining processes.

  As described above, the joining method according to the first embodiment includes a surface modification step, a surface hydrophilization step, a joining step, and a pressurizing step. In the surface modification step, the bonding surfaces (surfaces) W1j and W2j to which the upper wafer (first substrate) W1 and the lower wafer (second substrate) W2 are bonded are modified. In the surface hydrophilization step, the modified bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 are hydrophilized. In the bonding step, the hydrophilicized upper wafer W1 and lower wafer W2 are bonded by intermolecular force under normal temperature and normal pressure. In the pressurizing step, the temperature of the superposed wafer (polymerized substrate) T to which the upper wafer W1 and the lower wafer W2 are bonded is raised to a predetermined temperature higher than normal temperature, and the superposed wafer T is pressurized at a predetermined temperature. Thereby, generation | occurrence | production of a bubble between the upper wafer W1 and the lower wafer W2 can be suppressed, and wafer W1, W2 can be joined appropriately.

  In the bonding method according to the first embodiment, the upper wafer W1 and the lower wafer W2 in the bonding process are bonded to the superposed wafer T which is bonded with high accuracy at normal temperature and pressure, and the pressure is reduced at a high temperature. Generation of bubbles was suppressed by applying pressure below. Thereby, the quality of the superposed wafer T can be improved.

(Second Embodiment)
Next, a bonding method according to the second embodiment will be described. In the first embodiment described above, when the vacuum pump 714 is operated in the second flat plate portion 701 of the pressurizing device 32, the superposed wafer T is sucked and held over the entire holding surface 713.

  On the other hand, in the pressure device 32 according to the second embodiment, a plurality of suction areas are provided on the holding surface 713 of the second flat plate portion 701, and the superposed wafer T is suction-held for each suction area. It was configured as possible. According to the second flat plate portion 701 having such a configuration, for example, even a superposed wafer T having a relatively large warp can be reliably sucked and held.

<7. Configuration of Second Flat Plate Section According to Second Embodiment>
Hereinafter, the configuration of the second flat plate portion 701 according to the second embodiment will be described in detail with reference to FIGS. FIG. 21 is a schematic side view showing the configuration of the second flat plate portion 701. FIG. 22 is a schematic plan view when the second flat plate portion 701 is viewed from above. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 21 and 22, the second flat plate portion 701 has a main body portion 740 having a larger diameter than the superposed wafer T in plan view. On the upper surface of the main body 740, a plurality of pins 741 that are in contact with the lower surface (non-bonding surface W2n) of the overlapped wafer T are provided.

  The second flat plate portion 701 decompresses the suction region 742 by evacuating the suction region 742 on the holding surface 713 with a vacuum pump. As a result, the overlapped wafer T is sucked and held by the second flat plate portion 701.

  In addition, a first partition 745 and a second partition 746 are further provided on the upper surface of the main body 740, and the first flat plate 701 is adsorbed by the first partition 745 and the second partition 746. The region 742 is divided into three regions, a first region 742a, a second region 742b, and a third region 742c. In the above description, the adsorption region 742 is divided into three regions. However, the present invention is not limited to this, and the adsorption region 742 may be divided into two or four or more regions.

  Both the first partition wall portion 745 and the second partition wall portion 746 are formed to have an annular shape in plan view. Further, the second partition wall portion 746 is disposed on the outer peripheral side with respect to the first partition wall portion 745.

  Thus, the first region 742a sucks and holds the central portion of the overlapped wafer T from below. Further, the second region 742b sucks and holds a portion on the outer peripheral side of the overlapped wafer T with respect to the first region 742a. The third region 742c sucks and holds a portion on the outer peripheral side of the overlapped wafer T with respect to the second region 742b.

  A first suction port 751a, a second suction port 751b, and a third suction port 751c are formed in each of the first region 742a, the second region 742b, and the third region 742c. The first suction port 751a, the second suction port 751b, and the third suction port 751c include a first suction tube 752a, a second suction tube 752b, and a third suction tube 752c that communicate with different vacuum pumps 753a, 753b, and 753c, respectively. Connected. Thereby, the 2nd flat plate part 701 can adsorb | suck and hold the superposition | polymerization wafer T for every 1st area | region 742a, 2nd area | region 742b, and 3rd area | region 742c.

<8. Specific Operation of Second Flat Plate Part According to Second Embodiment>
Next, a specific operation of the second flat plate portion 701 configured as described above, specifically, an operation of sucking and holding the overlapped wafer T of the second flat plate portion 701 will be described with reference to FIGS. 23 to 24C. To do.

  FIG. 23 is a flowchart illustrating a processing procedure of a process of sucking and holding the overlapped wafer T by the second flat plate portion 701 among the processes executed by the bonding system 1. 24A to 24C are explanatory diagrams of the operation of the second flat plate portion 701. FIG.

  Note that the process shown in FIG. 23 is a process of attracting and holding the overlapped wafer T by the second flat plate portion 701, and therefore corresponds to, for example, the process of step S13 in the flowchart of FIG.

  In the following, as shown in FIG. 23, the pressurizing device 32 sucks and holds the overlapped wafer T only in the first region 742a of the second flat plate portion 701 by operating the vacuum pump 753a (step S13a). As a result, as shown in FIG. 24A, for example, in the overlapped wafer T where warpage has occurred, only the portion corresponding to the first region 742a, that is, the central portion of the overlapped wafer T is sucked from the second flat plate portion 701 and is held by suction. The In FIG. 24A and FIG. 24B, the warpage of the overlapped wafer T is exaggerated for convenience of understanding.

  Subsequently, in addition to the vacuum pump 753a, the pressurizing device 32 operates the vacuum pump 753b to suck and hold the overlapped wafer T in the first region 742a and the second region 742b (step S13b). Accordingly, as shown in FIG. 24B, the portions corresponding to the first region 742a and the second region 742b in the overlapped wafer T are sucked from the second flat plate portion 701 and sucked and held.

  That is, the pressurizing device 32 sucks and holds the central portion of the superposed wafer T in the first region 742a of the second flat plate portion 701, and then sucks and holds the outer peripheral portion of the superposed wafer T in the second region 742b.

  Subsequently, the pressurizing device 32 operates the vacuum pump 753c in addition to the vacuum pumps 753a and 753b, thereby superposing the overlapped wafer T in all regions of the first region 742a to the third region 742c of the second flat plate portion 701. Is held by suction (step S13c). As a result, as shown in FIG. 24C, all the portions corresponding to the first region 742a, the second region 742b, and the third region 742c in the overlapped wafer T are sucked from the second flat plate portion 701 and are held by suction.

  Therefore, for example, even if the overlapped wafer T having a relatively large warp is placed on the second flat plate portion 701, by gradually suctioning from the central portion of the overlapped wafer T toward the outer peripheral side, The warpage can be gradually extended to ensure the flatness of the superposed wafer T.

  The pressurizing device 32 holds the superposed wafer T, which is ensured to be flat, by electrostatic attraction by the electrostatic attraction unit 711 (step S13d). Thereby, in the 2nd flat plate part 701, even if it is the superposition | polymerization wafer T with a comparatively large curvature, for example, it becomes possible to adsorb and hold reliably.

  Further, since the overlapped wafer T is pressed in a state where the warp is extended, the pressure applied from the first flat plate portion 601 is transmitted uniformly or substantially uniformly to the overlapped wafer T. Thereby, in the pressurization apparatus 32 which concerns on 2nd Embodiment, while being able to extract the bubble between wafer W1, W2 efficiently, it can suppress that a crack etc. arise in the superposition | polymerization wafer T. .

  In the above-described embodiment, the temperature of the superposed wafer T is raised to the preheating temperature by the preheating device 31, but the invention is not limited to this. That is, for example, the preheating device 31 may be removed from the bonding system 1, and the pressurizing device 32 may be configured to raise the temperature of the superposed wafer T from room temperature to a predetermined temperature. In such a case, the joining system 1 can be simplified and miniaturized as much as the preheating device 31 is removed from the joining system 1.

  In the above description, the preheating device 31 and the pressurizing device 32 are separated from each other. However, the present invention is not limited to this. For example, the pressurizing device 32 may include the preheating device 31.

  Further, in the preheating device 31 and the pressurizing device 32 described above, the temperature of the superposed wafer T is raised using the heating mechanisms 311 and 411 and the first and second heating mechanisms 617 and 717, but the present invention is limited to this. It is not a thing. That is, for example, the temperature of the superposed wafer T may be increased by raising the environmental temperature in the chambers 501 and 810 using a temperature control mechanism or the like.

  In addition, the above-described pressurizing device 32 may be configured to include a cooling mechanism such as a water-cooling type or an air-cooling type to protect modules such as the pressurizing mechanism 802 and the decompression unit 820.

  Further, the transition device 50 may be configured to include a cooling mechanism for cooling the overlapped wafer T. Thereby, in the joining system 1, for example, after the superposed wafer T after pressure treatment is cooled by the transition device 50, it can be transported to the cassette C3.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

W1 Upper wafer W2 Lower wafer T Superposition wafer 1 Bonding system 2 Loading / unloading station 3 Processing station 30 Surface modification device 31 Preheating device 32 Pressurizing device 40 Surface hydrophilization device 41 Joining device 70 Control device 301 Upper flat plate portion 311 Heating mechanism 401 Lower flat plate portion 411 Heating mechanism 601 First flat plate portion 617 First heating mechanism 701 Second flat plate portion 717 Second heating mechanism 720 Support pin 742a First region 742b Second region 742c Third region 802 Pressure mechanism 820 Decompression unit

Claims (14)

A surface modification step for modifying the surfaces to be joined of the first substrate and the second substrate;
A surface hydrophilization step for hydrophilizing the surfaces of the modified first substrate and the second substrate;
A bonding step of bonding the hydrophilized first substrate and the second substrate by intermolecular force under normal temperature and normal pressure;
It causes to warm the first substrate and the second polymer substrate and the substrate is bonded to a higher than the normal temperature the predetermined temperature, see containing a pressurizing step of pressurizing the polymer substrate at the predetermined temperature,
The pressing step includes
The superposed substrate was placed on and supported on a support portion that can be raised and lowered provided on a surface of the second flat plate portion that is positioned below the superposed substrate and faces the superposed substrate, and supported by the support portion. Heating the superposed substrate in a state by a second heating mechanism provided on the second flat plate portion, and raising the temperature of the superposed substrate to the predetermined temperature while lowering the support portion. . The pressing step includes
The bonding method according to claim 1, wherein the polymerization substrate is pressurized under reduced pressure. The preheating step of raising the temperature of the superposed substrate bonded by the bonding step to a preheating temperature higher than the normal temperature and lower than the predetermined temperature is included before the pressurizing step. The joining method described. The predetermined temperature is
The joining method according to claim 1, wherein the joining surface of the superposed substrate is at a variable temperature. The pressing step includes
A first flat plate portion located above the polymerization substrate, and prior Symbol second flat plate portion, a first heating mechanism for heating the first flat plate portion, and the second heating mechanism for heating the second flat plate portion The method is performed using a pressurizing device including a pressurizing mechanism that pressurizes the superposed substrate by relatively moving the first flat plate portion and the second flat plate portion. 5. The joining method according to any one of 4 above. The pressing step includes
The bonding method according to any one of claims 1 to 5 , wherein the pressure is applied in a state where the superposed substrate is adsorbed and held from below. The pressing step includes
Wherein after the central portion of the polymerized substrate was suction-held from below, further claim 1-6, wherein the polymerization the outer peripheral side from the center of the substrate from below, characterized in that pressurized while holding adsorbed one The joining method as described in one. A surface modification device for modifying a surface to which the first substrate and the second substrate are bonded;
A surface hydrophilizing device that hydrophilizes the surfaces of the modified first and second substrates;
A bonding apparatus for bonding the hydrophilized first substrate and the second substrate by an intermolecular force under normal temperature and normal pressure;
A pressure device that raises the temperature of the polymerization substrate to which the first substrate and the second substrate are bonded to a predetermined temperature higher than the room temperature, and pressurizes the polymerization substrate at the predetermined temperature ;
The pressure device is
The superposed substrate was placed on and supported on a support portion that can be raised and lowered provided on a surface of the second flat plate portion that is positioned below the superposed substrate and faces the superposed substrate, and supported by the support portion. Heating the superposition substrate in a state by a second heating mechanism provided on the second flat plate portion, and raising the temperature of the superposition substrate to the predetermined temperature while lowering the support portion . The pressure device is
The joining system according to claim 8 , further comprising a decompression unit that decompresses the interior of the accommodation unit in which the superposed substrate is accommodated. The preheating device for raising the temperature of the superposed substrate joined by the joining device to a preheating temperature higher than the normal temperature and lower than the predetermined temperature before being pressurized by the pressurizing device. The joining system according to 8 or 9 . The predetermined temperature is
The joining system according to any one of claims 8 to 10 , wherein the joining surface of the superposed substrate has a variable temperature. The pressure device is
A first flat plate portion located above the superposed substrate;
Before Symbol and the second flat plate portion,
A first heating mechanism for heating the first flat plate portion;
Said second heating mechanism for heating the second flat plate portion,
According to any one of claims 8-11, characterized in that it comprises a pressure mechanism for pressurizing the polymer substrate by relatively moving the said the first flat plate portion second plate portion Joining system. The pressure device is
The joining system according to any one of claims 8 to 12, wherein the second flat plate portion is used to pressurize the superposed substrate while being adsorbed and held from below. The second flat plate portion is
A plurality of adsorption regions including a first region that adsorbs and holds the central portion of the superposed substrate from below, and a second region that adsorbs and holds a portion on the outer periphery side of the central portion from below in the superposed substrate;
The pressure device is
After the central portion of the superposed substrate is sucked and held in the first region of the second flat plate portion, the outer peripheral portion of the superposed substrate is sucked and held in the second region of the second flat plate portion. The joining system according to claim 8, wherein pressurization is performed.