JP6797267B2 - Joining system and joining method - Google Patents

Description

The disclosed embodiments relate to joining systems and joining methods .

Conventionally, in order to meet the demand for high integration of semiconductor devices, it has been proposed to use a three-dimensional integration technique for three-dimensionally stacking semiconductor devices. As an apparatus using this three-dimensional integration technology, for example, a joining apparatus for joining substrates such as semiconductor wafers (hereinafter referred to as "wafers") is known.

For example, in Patent Document 1, of two wafers arranged so as to face each other in the vertical direction, the central portion of the upper wafer is pressed by a pushing pin to bring the central portion into contact with the lower wafer, and then the upper wafer is provided. A technique for retracting a spacer supporting a wafer, bringing the entire surface of the upper wafer into contact with the entire surface of the lower wafer, and joining the substrates to each other is disclosed.

Japanese Unexamined Patent Publication No. 2004-207436

However, there is room for further improvement in the above-mentioned prior art in improving the bonding quality of the substrate.

Specifically, when the above-mentioned conventional technique is used, pressing only the upper wafer with the push pin causes the upper wafer to stretch more than the lower wafer, which may cause a misalignment in the bonding between the substrates. was there.

In this regard, for example, there is a method in which the lower wafer is preheated and thermally expanded to cancel the elongation of the upper wafer, but when such a method is used, distortion is likely to occur due to a slight temperature distribution difference in the wafer surface. There is a problem.

One aspect of the embodiment is intended to provide a bonding system and method capable of improving the bonding quality of the substrate.

The joining system according to one aspect of the embodiment is a joining system for joining the first substrate and the second substrate by an intermolecular force, and includes a surface modification device, a surface hydrophilic device, and a joining device. The surface reformer modifies the bonded surface of the first substrate and the second substrate by plasma of the processing gas. The surface hydrophilization device hydrophilizes the surfaces of the first substrate and the second substrate modified by the surface modifier. The joining device joins the first substrate and the second substrate that have been hydrophilized by the surface hydrophilic device. The joining device includes a first holding portion, a second holding portion, a deformation stage, and a control unit. The first holding portion holds the first substrate on the lower surface side. The second holding portion is provided below the first holding portion, and holds the second substrate facing the first substrate on the upper surface side. The deformation stage is arranged as the lower surface of the first holding portion and the upper surface of the second holding portion, and is formed so that the back surface side has a substantially spherical shape, and convex deformation is possible while holding the first substrate and the second substrate, respectively. It is provided in. The control unit brings the first holding portion and the second holding portion closer to each other in a state where the deformation stage is convexly deformed to bring the central portions of the first substrate and the second substrate into contact with each other, and then the convex deformation of the deformation stage The first substrate and the second substrate are joined by bringing the first holding portion and the second holding portion closer to each other while releasing the above .

According to one aspect of the embodiment, the bonding quality of the substrate can be improved.

FIG. 1 is a schematic plan view showing the configuration of the joining system according to the embodiment. FIG. 2 is a schematic side view showing the configuration of the joining system according to the embodiment. FIG. 3 is a schematic side view of the upper wafer and the lower wafer. FIG. 4 is a schematic plan view showing the configuration of the joining device. FIG. 5 is a schematic side view showing the configuration of the joining device. FIG. 6 is a schematic side view showing the configuration of the position adjusting mechanism. FIG. 7 is a schematic plan view showing the configuration of the reversing mechanism. FIG. 8 is a schematic side view (No. 1) showing the configuration of the reversing mechanism. FIG. 9 is a schematic side view (No. 2) showing the configuration of the reversing mechanism. FIG. 10 is a schematic side view showing the configuration of the holding arm and the holding member. FIG. 11 is a schematic side view showing the internal configuration of the joining device. FIG. 12A is a perspective view showing the configuration of the lower chuck. FIG. 12B is a deformation explanatory view of the lower chuck. FIG. 12C is a schematic cross-sectional view showing the configurations of the upper chuck and the lower chuck. FIG. 12D is a schematic plan view of the lower chuck when viewed from above. FIG. 13 is a flowchart showing a part of the processing procedure of the processing executed by the joining system. FIG. 14A is an operation explanatory view (No. 1) of the joining device. FIG. 14B is an operation explanatory view (No. 2) of the joining device. FIG. 14C is an operation explanatory view (No. 3) of the joining device. FIG. 14D is an operation explanatory view (No. 4) of the joining device. FIG. 14E is an operation explanatory view (No. 5) of the joining device. FIG. 14F is an operation explanatory view (No. 6) of the joining device. FIG. 14G is an operation explanatory view (No. 7) of the joining device. FIG. 14H is an operation explanatory view (No. 8) of the joining device. FIG. 14I is an operation explanatory view (No. 9) of the joining device. FIG. 15A is a schematic cross-sectional view showing the deformed structure of the deformation stage. FIG. 15B is a schematic plan view showing the deformation structure of the deformation stage. FIG. 15C is an explanatory diagram (No. 1) of the Z displacement and the X displacement of the deformation stage. FIG. 15D is an explanatory diagram (No. 2) of the Z displacement and the X displacement of the deformation stage. FIG. 16A is a schematic cross-sectional view showing another deformation structure of the deformation stage. FIG. 16B is a schematic plan view showing other deformation structures of the deformation stage.

Hereinafter, embodiments of the joining system and joining method disclosed in the present application will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments shown below.

In each drawing referred to below, in order to make the explanation easy to understand, an orthogonal coordinate system in which the vertical upward direction is the positive direction of the Z axis may be shown.

<1. Bonding system configuration>
First, the configuration of the joining system according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic plan view showing a configuration of a joining system according to the present embodiment, and FIG. 2 is a schematic side view of the same. Further, FIG. 3 is a schematic side view of the upper wafer and the lower wafer.

The joining system 1 according to the present embodiment shown in FIG. 1 forms a polymerized wafer T by joining the first substrate W1 and the second substrate W2 (see FIG. 3).

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. Further, 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.

In the following, the first substrate W1 will be referred to as “upper wafer W1” and the second substrate W2 will be referred to as “lower wafer W2”.

Further, in the following, as shown in FIG. 3, among the plate surfaces of the upper wafer W1, the plate surface on the side to be bonded to the lower wafer W2 is described as "bonding surface W1j", which is opposite to the bonding surface W1j. The plate surface is described as "non-bonded surface W1n". Further, among the plate surfaces of the lower wafer W2, the plate surface on the side to be bonded to the upper wafer W1 is described as "bonding surface W2j", and the plate surface on the side opposite to the bonding surface W2j is referred to as "non-bonding surface W2n". Describe.

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

The loading / unloading station 2 includes a mounting table 10 and a transport area 20. The mounting table 10 includes a plurality of mounting plates 11. Cassettes C1, C2, and C3 for accommodating a plurality of (for example, 25) substrates in a horizontal state are mounted on each mounting plate 11. For example, the cassette C1 is a cassette containing the upper wafer W1, the cassette C2 is a cassette containing the lower wafer W2, and the cassette C3 is a cassette containing the polymerized wafer T.

The transport area 20 is arranged adjacent to the X-axis positive direction side of the mounting table 10. The transport area 20 is provided with a transport path 21 extending in the Y-axis direction and a transport device 22 that can move along the transport path 21. The transfer device 22 can move not only in the Y-axis direction but also in the X-axis direction and can rotate around the Z-axis, and the cassettes C1 to C3 mounted on the mounting plate 11 and the processing station 3 described later The upper wafer W1, the lower wafer W2, and the polymerized wafer T are transferred to and from the third processing block G3.

The number of cassettes C1 to C3 mounted on the mounting plate 11 is not limited to the one shown in the drawing. Further, in addition to the cassettes C1, C2, and C3, a cassette or the like for collecting a defective substrate may be mounted on the mounting plate 11.

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

In the first processing block G1, a surface modification device 30 for modifying the joint surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 is arranged. The surface modifier 30 cuts the bond of SiO2 on the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 to form a single-bonded SiO, so that the bonding surface W1j, can be easily hydrophilized thereafter. Modify W2j.

In the surface reformer 30, for example, oxygen gas, which is a processing gas, is excited to be turned into plasma and ionized in a reduced pressure atmosphere. Then, by irradiating the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 with such oxygen ions, the bonding surfaces W1j and W2j are plasma-treated and modified.

A surface hydrophilic device 40 and a joining device 41 are arranged in the second processing block G2. The surface hydrophilization apparatus 40 hydrophilizes the joint surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 with pure water, and cleans the joint surfaces W1j and W2j. In the surface hydrophilization apparatus 40, 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, for example. As a result, the pure water supplied on 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 joining device 41 joins the upper wafer W1 and the lower wafer W2. The configuration of the joining device 41 will be described later.

As shown in FIG. 2, the third processing block G3 is provided with transition (TRS) devices 50 and 51 for the upper wafer W1, the lower wafer W2, and the polymerization wafer T in two stages in order from the bottom.

Further, as shown in FIG. 1, a transport region 60 is formed in a region surrounded by the first processing block G1, the second processing block G2, and the third processing block G3. A transport device 61 is arranged in the transport region 60. The transport device 61 has, for example, a transport arm that is movable in the vertical direction, the horizontal direction, and around the vertical axis. The transfer device 61 moves in the transfer area 60, and the upper wafer W1 and the lower wafer W2 are placed on predetermined devices in the first processing block G1, the second processing block G2, and the third processing block G3 adjacent to the transport area 60. And the polymerization wafer T is conveyed.

Further, as shown in FIG. 1, the joining system 1 includes a control device 70. The control device 70 controls the operation of the joining system 1. Such a control device 70 is, for example, a computer, and includes a control unit and a storage unit (not shown). A program that controls various processes such as joining process is stored in the storage unit. The control unit controls the operation of the junction system 1 by reading and executing the program stored in the storage unit.

The program may be recorded on a recording medium that can be read by a computer, and may be installed from the recording medium in the storage unit of the control device 70. Recording media that can be read by a computer include, for example, a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnet optical disk (MO), and a memory card.

<2. Configuration of joining device>
Next, the configuration of the joining device 41 will be described with reference to FIGS. 4 to 11. FIG. 4 is a schematic plan view showing the configuration of the joining device 41, and FIG. 5 is a schematic side view of the joining device 41. Further, FIG. 6 is a schematic side view showing the configuration of the position adjusting mechanism 210. Further, FIG. 7 is a schematic plan view showing the configuration of the reversing mechanism 220, and FIGS. 8 and 9 are schematic side views (No. 1) and (No. 2) of the same. Further, FIG. 10 is a schematic side view showing the configurations of the holding arm 221 and the holding member 222, and FIG. 11 is a schematic side view showing the internal configuration of the joining device 41.

As shown in FIG. 4, the joining device 41 has a processing container 190 whose inside can be sealed. A carry-in outlet 191 for the upper wafer W1, a lower wafer W2, and a polymerized wafer T is formed on the side surface of the processing container 190 on the transport region 60 side, and an opening / closing shutter 192 is provided at the carry-in outlet 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 above-mentioned carry-in outlet 191 is formed on the side surface of the processing container 190 in the transport region T1. Further, the upper wafer W1, the lower wafer W2, and the carry-in outlet 194 of the polymerized wafer T are also formed on the inner wall 193.

A transition 200 for temporarily placing the upper wafer W1, the lower wafer W2, and the polymerized wafer T is provided on the Y-axis negative direction side of the transport region T1. The transition 200 is formed in, for example, two stages, and any two of the upper wafer W1, the lower wafer W2, and the polymerization wafer T can be placed at the same time.

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

A position adjusting mechanism 210 for adjusting the horizontal orientation of the upper wafer W1 and the lower wafer W2 is provided on the Y-axis positive direction side of the transport region T1. As shown in FIG. 6, the position adjusting mechanism 210 detects the positions of the base 211, the holding portion 212 that attracts and holds the upper wafer W1 and the lower wafer W2 to rotate, and the notch portions of the upper wafer W1 and the lower wafer W2. It has a detection unit 213 and a detection unit 213.

In the position adjusting mechanism 210, the notches of the upper wafer W1 and the lower wafer W2 are detected by the detection unit 213 while rotating the upper wafer W1 and the lower wafer W2 that are attracted and held by the holding unit 212. The position of the portion is adjusted to adjust the horizontal orientation of the upper wafer W1 and the lower wafer W2.

Further, the transport region T1 is provided with an inversion mechanism 220 that inverts the front and back surfaces of the upper wafer W1. The reversing mechanism 220 has a holding arm 221 for holding the upper wafer W1 as shown in FIGS. 7 to 10.

The holding arm 221 extends in the horizontal direction. Further, the holding arm 221 is provided with holding members 222 for holding the upper wafer W1 at, for example, four places. As shown in FIG. 10, the holding member 222 is configured to be movable in the horizontal direction with respect to the holding arm 221. Further, a notch 223 for holding the outer peripheral portion of the upper wafer W1 is formed on the side surface of the holding member 222. These holding members 222 can hold the upper wafer W1 by sandwiching it.

As shown in FIGS. 7 to 9, the holding arm 221 is supported by a first drive unit 224 provided with, for example, a motor. The holding arm 221 is rotatable about a horizontal axis by the first driving unit 224. Further, the holding arm 221 is rotatable around the first drive unit 224 and is movable in the horizontal direction.

Below the first drive unit 224, a second drive unit 225 equipped with, for example, a motor is provided. The first drive unit 224 can be moved in the vertical direction along the support column 226 extending in the vertical direction by the second drive unit 225.

In this way, the upper wafer W1 held by the holding member 222 can be rotated about the horizontal axis and moved in the vertical and horizontal directions by the first drive unit 224 and the second drive unit 225. it can. Further, the upper wafer W1 held by the holding member 222 can rotate around the first drive unit 224 and move from the position adjusting mechanism 210 to the upper chuck 230 described later.

Further, as shown in FIG. 5, the processing region T2 is provided with an upper chuck 230 and a lower chuck 231. The upper chuck 230 attracts and holds the upper wafer W1 from above. Further, the lower chuck 231 is provided below the upper chuck 230, and sucks and holds the lower wafer W2 from below.

Further, as shown by the broken line, the upper chuck 230 and the lower chuck 231 can be convexally deformed while the upper wafer W1 and the lower wafer W2 are attracted and held, respectively. That is, the upper wafer W1 and the lower wafer W2 are also deformed on the holding surface according to the convex deformation of the holding surface. Hereinafter, such a holding surface will be referred to as a “deformation stage”. The specific configuration of the deformation stage will be described later with reference to FIGS. 12A and later.

As shown in FIG. 5, 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. 11) that images the joint 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.

Further, as shown in FIGS. 4, 5 and 11, the lower chuck 231 is supported by the first lower chuck moving portion 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 described later. Further, the first lower chuck moving portion 290 is configured so that the lower chuck 231 can be moved in the vertical direction and can be rotated around the vertical axis.

The first lower chuck moving unit 290 is provided with a lower imaging unit 291 that images the joint 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.

Further, as shown in FIGS. 4, 5 and 11, the first lower chuck moving portion 290 is provided on the lower surface side of the first lower chuck moving portion 290, and is a pair extending in the horizontal direction (Y-axis direction). It is attached to the rail 295 of. The first lower chuck moving portion 290 is configured to be movable along the rail 295.

The pair of rails 295 are provided on the second lower chuck moving portion 296. The second lower chuck moving portion 296 is provided on the lower surface side of the second lower chuck moving portion 296, and is attached to a pair of rails 297 extending in the horizontal direction (X-axis direction). Then, the second lower chuck moving portion 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 are provided on a mounting table 298 provided on the bottom surface of the processing container 190.

Next, the configurations of the upper chuck 230 and the lower chuck 231 will be described with reference to FIGS. 12A to 12D. As already described, in the present embodiment, both the upper chuck 230 and the lower chuck 231 have a deformation stage which is a holding surface capable of convex deformation. In such convex deformation, it is preferable that the upper chuck 230 and the lower chuck 231 behave in the same manner as each other. Therefore, in the present embodiment, the upper chuck 230 and the lower chuck 231 are arranged in the opposite directions. Has the same configuration.

Therefore, in FIGS. 12A to 12D, each component on the lower chuck 231 side is mainly illustrated. However, in FIGS. 12A to 12D, the reference numerals of the corresponding components on the upper chuck 230 side are also shown in parentheses.

FIG. 12A is a perspective view showing the configuration of the lower chuck 231. Further, FIG. 12B is a deformation explanatory view of the lower chuck 231. Further, FIG. 12C is a schematic cross-sectional view showing the configurations of the upper chuck 230 and the lower chuck 231. FIG. 12D is a schematic plan view of the lower chuck 231 when viewed from above.

As shown in FIGS. 12A and 12B, the lower chuck 231 includes a deformation stage 231a, a fixing ring 231b, and a base portion 231c. The deformation stage 231a is formed so as to have a substantially circular shape in a plan view and to have a flat plate shape on the surface side holding the lower wafer W2 in a non-deformed state.

The peripheral edge portion of the deformation stage 231a is fixed to the base portion 231c by the fixing ring 231b formed in a substantially annular shape. The base portion 231c is fixed to the above-mentioned first lower chuck moving portion 290 (see FIG. 4 and the like).

Further, the deformation stage 231a is provided so as to be capable of convex deformation (see arrow 1201 in FIG. 12B). The "convex deformation" referred to here means that the central portion of the deformation stage 231a is deformed so as to be displaced to a position higher than the peripheral portion, and as shown in FIG. 12B, from the peripheral portion of the deformation stage 231a. It is assumed that the case where the deformation stage 231a swells toward the central portion and becomes a part of a substantially spherical surface is included.

The structure for convexly deforming the deformation stage 231a is not limited, and for example, an air pressure may be used, or a piezo actuator or the like may be used. Here, the deformation stage 231a will be described until it is convexly deformed based on the control by the control device 70, and a more specific structure will be described later with reference to FIGS. 15A to 16B.

Further, as shown in FIG. 12C, the deformation stage 231a of the lower chuck 231 is divided into a plurality of, for example, three regions 231aa, 231ab, and 231ac. As shown in FIG. 12D, these regions 231aa, 231ab, and 231ac are provided in this order from the central portion to the peripheral portion (outer peripheral portion) of the lower chuck 231. The region 231aa has a circular shape in a plan view, and the regions 231ab and 231ac have an annular shape in a plan view.

As shown in FIG. 12C, suction tubes 260a, 260b, 260c for sucking and holding the lower wafer W2 are independently provided in each region 231aa, 231ab, and 231ac. Different vacuum pumps 261a, 261b, 261c are connected to the suction pipes 260a, 260b, 260c, respectively. As described above, the lower chuck 231 is configured so that the evacuation of the upper wafer W1 can be set for each of the regions 231aa, 231ab, and 231ac.

In FIG. 12D, two suction ports of the suction tube 260a are arranged in a straight line in the area 231aa, two suction ports of the suction tube 260b are arranged in the area 231ab, and two suction ports of the suction tube 260c are arranged in the area 231ac. However, the number and arrangement positions of each suction port are not limited.

Further, the regions 230aa, 230ab, 230ac on the upper chuck 230 side, the suction pipes 240a, 240b, 240c, and the vacuum pumps 241a, 241b, 241c are the regions 231aa, 231ab, 231ac, the suction pipes 260a, 260b, respectively on the lower chuck 231 side. It corresponds to 260c and vacuum pumps 261a, 261b and 261c.

<3. Specific operation of surface modifier, surface hydrophilization device, and joining device of joining system>
Next, the specific operations of the surface modifying device 30, the surface hydrophilizing device 40, and the joining device 41 configured as described above will be described with reference to FIGS. 13 to 14I.

FIG. 13 is a flowchart showing a part of the processing procedure of the processing executed by the joining system 1. 14A to 14I are operation explanatory views (No. 1) to (No. 9) of the joining device 41. The various processes shown in FIG. 13 are executed based on the 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 mounting plate 11 of the loading / unloading station 2. After that, the upper wafer W1 in the cassette C1 is taken out by the transfer device 22, and is transferred to the transition device 50 of the third processing block G3 of the processing station 3.

Next, the upper wafer W1 is transferred to the surface reforming device 30 of the first processing block G1 by the transfer device 61. In the surface reformer 30, oxygen gas, which is a processing gas, is excited to be turned into plasma and ionized under a predetermined reduced pressure atmosphere. The oxygen ions are irradiated on the bonding surface W1j of the upper wafer W1, and the bonding surface W1j is plasma-treated. As a result, the bonding surface W1j of the upper wafer W1 is modified (step S101).

Next, the upper wafer W1 is conveyed to the surface hydrophilic device 40 of the second processing block G2 by the transfer device 61. In the surface hydrophilization apparatus 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 reforming apparatus 30, and the bonding surface is concerned. W1j is hydrophilized. Further, the joint surface W1j of the upper wafer W1 is washed with the pure water (step S102).

Next, the upper wafer W1 is conveyed to the joining device 41 of the second processing block G2 by the conveying device 61. The upper wafer W1 carried into the joining device 41 is conveyed to the position adjusting mechanism 210 by the conveying mechanism 201 via the transition 200. Then, the position adjusting mechanism 210 adjusts the horizontal orientation of the upper wafer W1 (step S103).

After that, the upper wafer W1 is delivered from the position adjusting mechanism 210 to the holding arm 221 of the reversing mechanism 220. Subsequently, in the transport region T1, the front and back surfaces of the upper wafer W1 are inverted by inverting the holding arm 221 (step S104). That is, the bonding surface W1j of the upper wafer W1 is directed downward.

After that, the holding arm 221 of the reversing mechanism 220 rotates around the first drive unit 224 and moves below the upper chuck 230. Then, the upper wafer W1 is delivered from the reversing mechanism 220 to the upper chuck 230. The non-bonded surface W1n of the upper wafer W1 is adsorbed and held by the upper chuck 230 (step S105).

At this time, all the vacuum pumps 241a, 241b, 241c are operated, and the upper wafer W1 is evacuated in all the regions 230aa, 230ab, 230ac of the upper chuck 230. The upper wafer W1 waits on the upper chuck 230 until the lower wafer W2, which will be described later, is conveyed to the joining device 41.

While the processing of steps S101 to S105 described above is being performed on the upper wafer W1, the processing of the lower wafer W2 is performed. First, the lower wafer W2 in the cassette C2 is taken out by the transfer device 22, and is transferred to the transition device 50 of the processing station 3.

Next, the lower wafer W2 is conveyed to the surface modification device 30 by the transfer device 61, and the bonding surface W2j of the lower wafer W2 is modified (step S106). The modification of the joint surface W2j of the lower wafer W2 in step S106 is the same as in step S101 described above.

After that, the lower wafer W2 is conveyed to the surface hydrophilization device 40 by the transfer device 61, the bonding surface W2j of the lower wafer W2 is hydrophilized, and the bonding surface W2j is washed (step S107). The hydrophilization and cleaning of the joint surface W2j of the lower wafer W2 in step S107 is the same as in step S102 described above.

After that, the lower wafer W2 is conveyed to the joining device 41 by the conveying device 61. The lower wafer W2 carried into the joining device 41 is conveyed to the position adjusting mechanism 210 by the conveying mechanism 201 via the transition 200. Then, the position adjusting mechanism 210 adjusts the horizontal orientation of the lower wafer W2 (step S108).

After that, the lower wafer W2 is conveyed to the lower chuck 231 by the conveying mechanism 201, and is attracted and held by the lower chuck 231 (step S109). At this time, all the vacuum pumps 261a, 261b, and 261c are operated, and the lower wafer W2 is evacuated in all the regions 231aa, 231ab, and 231ac of the lower chuck 231. Then, the non-bonding surface W2n of the lower wafer W2 is attracted and held by the lower chuck 231 so that the bonding surface W2j of the lower wafer W2 faces upward.

Next, the horizontal position adjustment between the upper wafer W1 held by the upper chuck 230 and the lower wafer W2 held by the lower chuck 231 is performed (step S110).

Prior to the position adjustment, as shown in FIG. 14A, a plurality of predetermined reference points A1 to A3, for example, three reference points A1 to A3 are set on the joint surface W1j of the upper wafer W1, and similarly, the lower wafer W2. A plurality of predetermined reference points B1 to B3, for example, three reference points B1 to B3 are set on the joint surface W2j. As the 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 set arbitrarily.

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 located substantially below the upper imaging unit 281. Then, the common target X is confirmed between the upper imaging unit 281 and the lower imaging unit 291. 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. Be adjusted.

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

Specifically, while the lower chuck 231 is moved in the horizontal direction by the first lower chuck moving portion 290 and the second lower chuck moving portion 296, the reference point B1 of the joint surface W2j of the lower wafer W2 is used by using the upper imaging unit 281. ~ 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 junction surface W1j of the upper wafer W1. Note that FIG. 14B shows a state in which the reference point B1 of the lower wafer W2 is imaged by the upper imaging unit 281 and the reference point A1 of the upper wafer W1 is imaged by the lower imaging unit 291.

The captured image data is output to the control device 70. In the control device 70, the reference points A1 to A3 of the upper wafer W1 and the reference points B1 to B3 of the lower wafer W2 are based on the image data captured by the upper imaging unit 281 and the image data captured by the lower imaging unit 291. The horizontal position of the lower chuck 231 is adjusted by the first lower chuck moving portion 290 and the second lower chuck moving portion 296 so that the two are matched with each other. In this way, 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.

FIG. 14C shows the state of the upper chuck 230, the upper wafer W1, the lower chuck 231 and the lower wafer W2 after the processing up to the above-mentioned step S110 is completed. As shown in FIG. 14C, the upper wafer W1 is evacuated and held in all regions 230aa, 230ab, 230ac of the upper chuck 230, and the lower wafer W2 is also evacuated in all regions 231aa, 231ab, 231ac of the lower chuck 231. It is pulled and held.

Next, as shown in FIG. 14D, the deformation stages 230a and 231a of the upper chuck 230 and the lower chuck 231 are convexly deformed in a state where both the upper wafer W1 and the lower wafer W2 are evacuated and held (in the figure). See arrow 1401, step S111). As a result, the upper wafer W1 and the lower wafer W2 are warped from each other, the central portion C is closest to each other, and the peripheral portion E is most distant from each other.

Next, as shown in FIG. 14E, the lower chuck 231 is moved vertically upward by the first lower chuck moving portion 290 to adjust the vertical positions of the upper chuck 230 and the lower chuck 231, and the upper chuck 230 is moved to the upper chuck 230. The vertical positions of the held upper wafer W1 and the lower wafer W2 held by the lower chuck 231 are adjusted (step S112). After that, such adjustment is appropriately performed in the process of joining the upper wafer W1 and the lower wafer W2.

Next, the joining process of the upper wafer W1 and the lower wafer W2 is performed. Specifically, as shown in FIG. 14F, the lower chuck 231 is vertically upward by the first lower chuck moving portion 290 in order to bring the upper wafer W1 and the lower wafer W2, which are deformed by convexly deforming the deformation stages 230a and 231a, to approach each other. (See arrow 1402 in the figure). Then, the central portions C of the upper wafer W1 and the lower wafer W2 are brought into contact with each other (step S113).

Then, when the central portions C of the upper wafer W1 and the lower wafer W2 come into contact with each other, the deformation stages 230a, 231a are formed so that the convex shapes of the deformation stages 230a, 231a gradually return to the flat plate shape, as shown in FIG. 14G. The convex deformation of is gradually released (see arrow 1403 in the figure, step S114). Further, at this time, the lower chuck 231 is moved vertically upward by the first lower chuck moving portion 290 so that the contact portion between the upper wafer W1 and the lower wafer W2 gradually expands from the central portion C toward the peripheral portion E (the first lower chuck moving portion 290). See arrow 1404 in the figure, step S114).

As a result, the upper wafer W1 and the lower wafer W2 are gradually joined. That is, since the joint surface W1j of the upper wafer W1 and the joint surface W2j of the lower wafer W2 are modified in steps S101 and S106, respectively, a van der Waals force (intermolecular force) is first generated between the joint surfaces W1j and W2j. The joint surfaces W1j and W2j are joined to each other.

Further, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are hydrophilized in steps S102 and S107, respectively, the hydrophilic groups between the bonding surfaces W1j and W2j are hydrogen-bonded, and the bonding surfaces W1j and W2j are bonded. They are firmly joined to each other. The Van der Waals force between the bonding surfaces W1j and W2j and the bonding by hydrogen bonding gradually expand from the central portion C toward the peripheral portion E as the lower chuck 231 approaches the upper chuck 230.

It should be noted that the release of the convex deformation of the deformation stages 230a and 231a in step S114 and the vertical upward movement of the lower chuck 231 are performed not only at a constant speed, but also, for example, the lower chuck 231 approaches the upper chuck 230 and moves upward. As the contact portion between the wafer W1 and the lower wafer W2 expands, the speed may be reduced. As a result, it is possible to suppress the generation of air bubbles near the peripheral edges E of the upper wafer W1 and the lower wafer W2 after joining.

Then, as shown in FIG. 14H, the deformation stages 230a and 231a return to a flat plate shape, and the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are in contact with each other on the entire surface, so that the upper wafer W1 and the lower wafer W2 come into contact with each other. It is joined (step S115). Then, the operation of the vacuum pumps 241a, 241b, 241c on the upper chuck 230 side is stopped, and the vacuum drawing of the upper wafer W1 from the suction pipes 240a, 240b, 240c is stopped.

After that, as shown in FIG. 14I, the lower chuck 231 is moved vertically downward by the first lower chuck moving portion 290 (see arrow 1405 in the figure). Then, the operation of the vacuum pumps 261a, 261b, 261c on the lower chuck 231 side is stopped, the vacuum drawing of the lower wafer W2 from the suction pipes 260a, 260b, 260c is stopped, and the lower chuck 231 sucks and holds the lower wafer W2. To cancel. As a result, the joining process in the joining device 41 is completed.

<4. Specific example of deformed structure of upper chuck and lower chuck>
Next, specific examples of the modified structures of the upper chuck 230 and the lower chuck 231 will be described with reference to FIGS. 15A to 16B. Although the lower chuck 231 side is mainly illustrated in FIGS. 15A to 16B, the upper chuck 230 side also has the same configuration except that the orientation of the upper chuck 230 is upside down.

First, as an example, a case where the deformed structure utilizes air pressure will be described with reference to FIGS. 15A to 15D. FIG. 15A is a schematic cross-sectional view showing the deformed structure of the deformation stage 231a. Further, FIG. 15B is a schematic plan view showing the deformation structure of the deformation stage 231a. 15C and 15D are explanatory views (No. 1) and (No. 2) of the displacement (Z displacement) in the Z direction and the displacement (X displacement) in the X direction of the deformation stage 231a.

As shown in FIGS. 15A and 15B, when air pressure is used, the base portion 231c is provided with an air supply pipe 270a by opening a supply port on the upper surface of the base portion 231c. The air supply pipe 270a is connected to the vacuum pump 270b, and by the operation of the vacuum pump 270b, air is supplied and discharged to the internal space surrounded by the upper surface of the base portion 231c and the back surface of the deformation stage 231a (arrow 1501 in FIG. 15A). reference).

The deformation stage 231a is deformed according to a change in internal pressure due to supply and discharge of air from the air supply pipe 270a. That is, the deformation stage 231a is convexly deformed by supplying air from the air supply pipe 270a and increasing the internal pressure of the internal space described above, and the air is discharged from the air supply pipe 270a to reduce the internal pressure of the internal space on the surface. Returns to a flat plate (see arrow 1502 in FIG. 15A). Although the number of air supply pipes 270a is one in FIGS. 15A and 15B, a plurality of air supply pipes 270a may be provided.

Further, as the material of the deformation stage 231a, various materials such as aluminum material, silicon carbide (SIC), and zirconia (ZrO2) can be used.

Further, as shown in FIG. 15A, in the deformation stage 231a, the back surface side has a substantially spherical shape, that is, the contour of the back surface side in cross-sectional view draws an arc from the central portion CT to the peripheral portion ET, and the meat is formed. It is formed into a shape in which the thickness Th gradually decreases.

As shown in FIG. 15C, when the Z displacement and the X displacement when the deformation stage 231a is convexly deformed with the vertical direction as the Z direction and the radial direction of the deformation stage 231a as the X direction, the deformation stage 231a This is because the X-displacement can be made close to linear as shown in FIG. 15D by forming the back surface side into a shape in which the wall thickness Th shown in FIG. 15A gradually decreases.

As a result, the deformation stage 231a can be uniformly displaced in the circumferential direction (aggregation in the radial direction). That is, the entire surface of the deformation stage 231a can be convexally deformed without bias in the circumferential direction, which can contribute to improving the joining accuracy.

Further, as shown in FIGS. 15A and 15B, the deformation stage 231a has annular protrusions 231ad and 231ae arranged concentrically about the central portion CT on the back surface side thereof. Although there are two here, the number is not limited.

The annular projections 231ad and 231ae are provided with, for example, an annular projection 231ad corresponding to the boundary of the regions 231aa and 231ab and an annular projection 231ae corresponding to the boundary of the regions 231ab and 231ac, respectively, and the back surface side of the deformation stage 231a is a region. It is divided so as to correspond to 231aa, 231ab, and 231ac.

As a result, in the process of convex deformation of the deforming stage 231a to be deformed, as shown in FIG. 15B, the air supplied from the vacuum pump 270b via the air supply pipe 270a has a diameter exceeding the annular protrusions 231ae and 231ad. While supplying to the central CT along the direction, it is possible to easily distribute each region 231ac, 231ab, 231aa along the circumferential direction (see each arrow on the deformation stage 231a in the figure).

That is, air can be uniformly supplied to the back surface side of the deformation stage 231a, which can contribute to the uneven convex deformation of the deformation stage 231a.

Next, as another example, a case where the deformed structure utilizes a piezo actuator will be described with reference to FIGS. 16A and 16B.

FIG. 16A is a schematic cross-sectional view showing another deformation structure of the deformation stage 231a. Further, FIG. 16B is a schematic plan view showing other deformation structures of the deformation stage 231a. In addition, in FIG. 16A and FIG. 16B, the reference numeral "231A" is attached to the lower chuck.

As shown in FIGS. 16A and 16B, when a piezo actuator is used, a plurality, for example, one piezo actuator PZ-C and four piezo actuators PZ-E are provided inside the base portion 231c.

The piezo actuators PZ-C and PZ-E are arranged so that the top piece TP, which is a movable part, faces vertically upward. For example, the piezo actuator PZ-C is located at a position corresponding to the central CT of the deformation stage 231a. The actuators PZ-E are arranged at equal intervals on the same circle near the peripheral edge portion ET of the deformation stage 231a. That is, it is preferable that the piezo actuators PZ-C and PZ-E are arranged so as to have symmetry as a whole depending on their respective arrangement positions. As a result, it is possible to contribute to uniformly applying a force to the deformation stage 231a.

Further, above the piezo actuator PZ-C, a center member 231ca formed in a substantially circular shape having a diameter larger than that of the top piece TP in a plan view is arranged. Further, above the piezo actuator PZ-E, a ring member 231 kb formed in a substantially annular shape extending in a width larger than the diameter of the top piece TP in a plan view is arranged.

The piezo actuators PZ_C and PZ_E have piezo elements stacked inside, and each top piece TP is moved up and down according to a change in voltage from a voltage generator (not shown) connected to each of them. The deformation stage 231a is deformed according to the movement of each of the top pieces TP.

Specifically, the piezo actuator PZ_C raises and lowers the center member 231ca in contact with the top piece TP by the top piece TP (see arrow 1601 in FIG. 16A). Further, the piezo actuator PZ_E raises and lowers the ring member 231 cc in contact with each of the top piece TPs by the top piece TP (see arrow 1602 in FIG. 16A).

Then, in response to the movements of the center member 231ca and the ring member 231cc, the deformation stage 231a is convexly deformed or the surface is returned to a flat plate shape (see arrow 1603 in FIG. 16A). The center member 231ca and the ring member 231cc are examples of "dispersion members" that play a role of distributing the load and uniformly deforming the deformation stage 231a.

In this way, the deformation structure of the deformation stage 231a can also be configured by using the piezo actuators PZ_C and PZ_E. Needless to say, any actuator capable of converting the input energy into physical motion in the vertical direction is not limited to the piezo actuators PZ_C and PZ_E.

In the joining system 1 according to the present embodiment configured as described above, in the joining device 41, the upper chuck 230 and the lower chuck 231 are convexly deformed in the same manner, and the upper wafer W1 and the lower wafer are held by them. Since the W2 is warped substantially the same and then joined, it is possible to prevent one of the upper wafer W1 and the lower wafer W2 from extending from the other. Therefore, according to this embodiment, the bonding quality of the substrate can be improved.

Further, in the joining system 1 according to the present embodiment, it is not necessary to use the method of preheating the upper wafer W1 and the lower wafer W2 in the joining device 41. Therefore, distortion due to the temperature distribution difference does not occur. That is, according to the present embodiment, the bonding quality of the substrate can be improved.

Further, in the joining system 1 according to the present embodiment, when the upper chuck 230 and the lower chuck 231 are brought close to each other in the joining device 41, they are brought close to each other, for example, at a low speed as the contact portion between the upper wafer W1 and the lower wafer W2 expands. Therefore, it is possible to suppress the generation of air bubbles in the vicinity of the peripheral edge portion E of the upper wafer W1 and the lower wafer W2 after joining. Therefore, according to this embodiment, the bonding quality of the substrate can be improved.

As described above, the joining device 41 according to the present embodiment includes an upper chuck 230 (corresponding to an example of the "first holding portion") and a lower chuck 231 (corresponding to an example of the "second holding portion"). It includes deformation stages 230a and 231a, and a control device 70 (corresponding to an example of a "control unit").

The upper chuck 230 holds the upper wafer W1 (corresponding to an example of the "first substrate") on the lower surface side. The lower chuck 231 is provided below the upper chuck 230, and holds the lower wafer W2 (corresponding to an example of the "second substrate") facing the upper wafer W1 on the upper surface side.

The deformation stages 230a and 231a are arranged as the lower surface of the upper chuck 230 and the upper surface of the lower chuck 231, and are provided so as to be capable of convex deformation while holding the upper wafer W1 and the lower wafer W2, respectively.

The control device 70 brings the upper chuck 230 and the lower chuck 231 close to each other in a state where the deformation stages 230a and 231a are convexly deformed to bring the upper wafer W1 and the lower wafer W2 into contact with each other, and then the deformation stage. The upper wafer W1 and the lower wafer W2 are joined by bringing the upper chuck 230 and the lower chuck 231 closer to each other while releasing the convex deformation of the 230a and 231a.

Therefore, according to the joining device 41 according to the present embodiment, the joining quality of the substrate can be improved.

In the above-described embodiment, the case where the lower chuck 231 is brought closer to the upper chuck 230 along the vertical direction is given as an example, but the upper chuck 230 may be brought closer to the lower chuck 231.

Further, in the above-described embodiment, the case where air is supplied by using a vacuum pump or the like is given as an example, but an electropneumatic regulator or the like capable of supplying air at a predetermined pressure while strictly controlling it is used. May be good.

Further, in the above-described embodiment, the case where air is supplied to and discharged from the internal space on the back surface side of the deformation stages 230a and 231a is given as an example, but the internal pressure of the internal space may be changed, and the fluid is not limited to air. All you need is.

Further effects and variations can be easily derived by those skilled in the art. For this reason, the broader aspects of the invention are not limited to the particular details and representative embodiments expressed and described as described above. Therefore, various modifications can be made without departing from the spirit or scope of the general concept of the invention as defined by the appended claims and their equivalents.

1 Joining system 2 Carrying in / out station 3 Processing station 30 Surface reforming device 40 Surface hydrophilizing device 41 Joining device 70 Control device 230 Upper chuck 230a Deformation stage 231,231A Lower chuck 231a Deformation stage 231ad Ring protrusion 231ae Ring protrusion 231b Fixing ring 231c Base part 231ca Center member 231cc Ring member PZ-C Piezo actuator PZ-E Piezo actuator TP Top piece W1 Upper wafer W2 Lower wafer

Claims (7)

A joining system that joins the first substrate and the second substrate by intermolecular force.
A surface reformer that modifies the bonded surfaces of the first substrate and the second substrate with plasma of processing gas, and
A surface hydrophilic device that hydrophilizes the surfaces of the first substrate and the second substrate modified by the surface modifier, and
The first substrate and the joining device for joining the second substrate, which have been hydrophilized by the surface hydrophilic device, are provided.
The joining device is
A first holding portion that holds the first substrate on the lower surface side,
A second holding portion provided below the first holding portion and holding the second substrate facing the first substrate on the upper surface side.
It is arranged as the lower surface of the first holding portion and the upper surface of the second holding portion, is formed so that the back surface side has a substantially spherical shape, and is convexly deformed while holding the first substrate and the second substrate, respectively. With the deformation stage provided so that
After the first holding portion and the second holding portion are brought into close contact with each other in a state where the deformation stage is convexly deformed, the central portions of the first substrate and the second substrate are brought into contact with each other, and then the deformation stage A joining system comprising a control unit for joining the first substrate and the second substrate by bringing the first holding portion and the second holding portion closer to each other while releasing the convex deformation. The bonding system according to claim 1 , further comprising a position adjusting mechanism for adjusting the horizontal orientation of each of the first substrate and the second substrate hydrophilized by the surface hydrophilic device before bonding. .. 2. The second aspect of the present invention is characterized in that a holding arm for inverting the front and back surfaces of the first substrate by inverting the first substrate whose orientation is adjusted in the horizontal direction by the position adjusting mechanism is further provided. The joining system described. The joining device has a processing container that can be sealed inside.
The joining system according to claim 3 , wherein the position adjusting mechanism and the holding arm are arranged in the same section in the processing container. The control unit
As the contact portions of the first substrate and the second substrate expand, the convex deformation of the deformation stage is released, and the approach of the first holding portion and the second holding portion is slowed down. The joining system according to any one of claims 1 to 4 . A first holding portion for holding the first substrate on the lower surface side, a second holding portion provided below the first holding portion and holding the second substrate facing the first substrate on the upper surface side, and the above. It is arranged as the lower surface of the first holding portion and the upper surface of the second holding portion, and is formed so that the back surface side has a substantially spherical shape, and convex deformation occurs while holding the first substrate and the second substrate, respectively. It is a joining method using a joining device including a deformable stage provided, and includes a control step of joining the first substrate and the second substrate.
The control step is
After the first holding portion and the second holding portion are brought into close contact with each other in a state where the deformation stage is convexly deformed, the central portions of the first substrate and the second substrate are brought into contact with each other, and then the deformation stage The first substrate and the second substrate are joined by bringing the first holding portion and the second holding portion closer to each other while releasing the convex deformation.
A joining method characterized by. The control step is
As the contact portions of the first substrate and the second substrate expand, the convex deformation of the deformation stage is released, and the approach of the first holding portion and the second holding portion is slowed down.
6. The joining method according to claim 6.

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