阅读说明：本技术 接合系统和接合方法 (Joining system and joining method ) 是由 前田浩史 三村勇之 饭野克宏 古屋径荣 坂本亮一 山崎亮 于 2020-02-28 设计创作，主要内容包括：一种接合系统,具备：表面改性装置,其在减压气氛下对第一基板的包括金属层的接合面和第二基板的包括金属层的接合面一边加热一边改性；以及接合装置,其将所述改性后的所述第一基板的所述接合面和所述改性后的所述第二基板的所述接合面相对来进行接合,所述接合系统还具备：大气搬送装置,其在充满常压的大气的大气搬送区域中搬送所述第一基板和所述第二基板；加载互锁装置,其在用于在所述大气搬送区域与表面改性装置之间搬送所述第一基板和所述第二基板的搬送路径的中途形成切换气压的加载互锁室；以及冷却装置,其在将所述改性后的所述第一基板和所述改性后的所述第二基板中的至少一个基板从所述加载互锁室搬出至所述大气搬送区域之前冷却所述至少一个基板。(A joining system is provided with: a surface modification device that modifies a bonding surface of the first substrate including the metal layer and a bonding surface of the second substrate including the metal layer while heating the bonding surfaces in a reduced pressure atmosphere; and a bonding apparatus that bonds the bonding surface of the modified first substrate and the bonding surface of the modified second substrate to each other, the bonding apparatus being configured to face each other, the bonding system further including: an atmospheric transfer device that transfers the first substrate and the second substrate in an atmospheric transfer area filled with atmospheric air at normal pressure; a load lock device that forms a load lock chamber that switches air pressure in the middle of a transfer path for transferring the first substrate and the second substrate between the atmospheric transfer area and the surface modification device; and a cooling device that cools at least one of the first substrate after the modification and the second substrate after the modification before the at least one substrate is carried out from the load-lock chamber to the atmospheric transfer area.)

1. A joining system is provided with: a surface modification device that modifies a bonding surface of the first substrate including the metal layer and a bonding surface of the second substrate including the metal layer while heating the bonding surfaces in a reduced pressure atmosphere; a surface hydrophilization device which hydrophilizes the bonding surface of the first substrate after the modification and the bonding surface of the second substrate after the modification; and a bonding apparatus that bonds the bonding surface of the first substrate after hydrophilization and the bonding surface of the second substrate after hydrophilization in an opposing manner, the bonding system further comprising:

an atmospheric transfer device that transfers the first substrate and the second substrate in an atmospheric transfer area filled with atmospheric air at normal pressure;

a load lock device that forms a load lock chamber that switches air pressure in the middle of a transfer path for transferring the first substrate and the second substrate between the atmospheric transfer area and the surface modification device; and

a cooling device that cools at least one of the first substrate after the modification and the second substrate after the modification before the at least one substrate is carried out from the load-lock chamber to the atmospheric transfer area.

2. The joining system of claim 1,

the cooling device has an internal cooling unit that cools at least one of the modified first substrate and the modified second substrate inside the load-lock chamber.

3. The joining system of claim 2,

the internal cooling unit has an inert gas supply unit that supplies an inert gas to the inside of the load-lock chamber.

4. The joining system of claim 3,

the inert gas supply unit includes a gas cooling mechanism that cools the inert gas before being supplied to the interior of the load-lock chamber.

5. The joining system according to claim 3 or 4,

the inert gas supply unit has a supply port for supplying the inert gas at a position facing at least one of the first substrate and the second substrate housed in the load-lock chamber.

6. The joining system according to any one of claims 3 to 5,

the inert gas supply section has a diffuser that restores the gas pressure of the load-lock chamber to normal pressure by supplying the inert gas to the load-lock chamber.

7. The joining system of claim 6,

the supply port of the diffuser through which the inert gas is supplied is formed of a porous material.

8. The joining system according to any one of claims 2 to 7,

the internal cooling unit includes a temperature adjustment plate portion disposed inside the load-lock chamber, and a coolant supply portion that supplies a coolant to an internal flow path of the temperature adjustment plate portion.

9. The joining system of claim 8,

the internal cooling unit includes a space changing unit that changes a space between the temperature adjustment plate portion and at least one of the first substrate and the second substrate.

10. The joining system of any one of claims 1 to 9,

the cooling device has an external cooling unit that cools at least one of the modified first substrate and the modified second substrate outside the load-lock chamber,

the joining system is provided with a vacuum transfer region of reduced pressure atmosphere adjacent to the cooling section for exterior, the load-lock apparatus, and the surface modification apparatus,

the external cooling unit includes a cooling container, a substrate holding unit for holding at least one of the first substrate and the second substrate in a reduced-pressure atmosphere inside the cooling container, and a coolant supply unit for supplying a coolant to an internal flow path of the substrate holding unit.

11. A bonding method comprising the steps of: modifying the bonding surface of the first substrate including the metal layer and the bonding surface of the second substrate including the metal layer by a surface modification apparatus under a reduced pressure atmosphere while heating; hydrophilizing the bonding surface of the first substrate after the modification and the bonding surface of the second substrate after the modification; and joining the bonding surface of the first substrate after hydrophilization and the bonding surface of the second substrate after hydrophilization in an opposed manner, the joining method further comprising:

transporting the first substrate and the second substrate in an atmospheric transport region filled with atmospheric air at normal pressure;

switching an air pressure inside a load-lock chamber formed in the middle of a transfer path that transfers the first substrate and the second substrate between the atmospheric transfer area and the surface modification apparatus; and

cooling at least one of the modified first substrate and the modified second substrate before the at least one substrate is carried out of the load-lock chamber to the atmospheric transport region.

12. The joining method according to claim 11,

the cooling step includes cooling at least one of the modified first substrate and the modified second substrate inside the load-lock chamber.

13. The joining method according to claim 12,

the step of cooling includes supplying an inert gas to the interior of the load-lock chamber.

14. The joining method according to claim 13,

the step of cooling includes cooling the inert gas before being supplied to the interior of the load-lock chamber.

15. The joining method according to any one of claims 12 to 14,

the cooling step includes supplying a coolant to an internal flow path of the temperature adjustment plate portion disposed inside the load-lock chamber.

16. The joining method according to claim 15,

the step of cooling includes changing an interval between the temperature adjustment plate portion and at least one of the first substrate and the second substrate.

17. The joining method according to any one of claims 11 to 16,

the step of performing the cooling includes cooling at least one of the first substrate after the modification and the second substrate after the modification inside a cooling container provided outside the load-lock chamber,

the bonding method includes the steps of: transporting the first substrate and the second substrate in a vacuum transport region of reduced pressure atmosphere adjacent to the cooling vessel, the surface modification apparatus, and the load-lock chamber,

the step of cooling includes supplying a coolant to an internal flow path of a substrate holding unit that holds at least one of the first substrate and the second substrate in a reduced-pressure atmosphere inside the cooling container.

Technical Field

The present disclosure relates to a joining system and a joining method.

Background

The bonding system described in patent document 1 includes a surface modification device for modifying the surface of a substrate to be bonded, a surface hydrophilization device for hydrophilizing the surface of the substrate modified by the surface modification device, and a bonding device for bonding the substrates whose surfaces have been hydrophilized by the surface hydrophilization device. In this bonding system, the surface of the substrate is modified by plasma treatment in the surface modification device, and then the surface of the substrate is hydrophilized by supplying pure water to the surface of the substrate in the surface hydrophilization device. Then, the two substrates arranged in opposition to each other are bonded together by van der waals force and hydrogen bonding in the bonding apparatus.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-39364

Disclosure of Invention

Problems to be solved by the invention

One embodiment of the present disclosure provides a technique capable of suppressing oxidation of a metal layer included in a bonding surface of a modified substrate.

Means for solving the problems

A joining system according to one aspect of the present disclosure includes: a surface modification device that modifies a bonding surface of the first substrate including the metal layer and a bonding surface of the second substrate including the metal layer while heating the bonding surfaces in a reduced pressure atmosphere; a surface hydrophilization device which hydrophilizes the bonding surface of the first substrate after the modification and the bonding surface of the second substrate after the modification; and a bonding apparatus that bonds the bonding surface of the first substrate after hydrophilization and the bonding surface of the second substrate after hydrophilization in an opposing manner, wherein the bonding system further comprises: an atmospheric transfer device that transfers the first substrate and the second substrate in an atmospheric transfer area filled with atmospheric air at normal pressure; a load lock device that forms a load lock chamber that switches air pressure in the middle of a transfer path for transferring the first substrate and the second substrate between the atmospheric transfer area and the surface modification device; and a cooling device that cools at least one of the first substrate after the modification and the second substrate after the modification before the at least one substrate is carried out from the load-lock chamber to the atmospheric transfer area.

ADVANTAGEOUS EFFECTS OF INVENTION

According to one embodiment of the present disclosure, oxidation of the metal layer included in the bonding surface of the modified substrate can be suppressed.

Drawings

Fig. 1 is a plan view showing a joining system according to an embodiment.

Fig. 2 is a front view showing a joining system according to an embodiment.

Fig. 3 is a side view showing a state before the first substrate and the second substrate are bonded according to the embodiment.

Fig. 4 is a side view showing a state after the first substrate and the second substrate are bonded according to the embodiment.

Fig. 5 is a diagram showing a load-lock apparatus and a cooling apparatus according to an embodiment.

Fig. 6 is a flowchart showing a process up to the modification of the surface of the first substrate according to one embodiment.

Fig. 7 is a flowchart showing a process until the first substrate with the modified surface is carried out to the atmospheric transfer area according to one embodiment.

Fig. 8 is a flowchart showing the main steps of the bonding method according to the embodiment.

Fig. 9 is a diagram showing a load-lock apparatus and a cooling apparatus according to a first modification.

Fig. 10 is a plan view showing a bonding system according to a second modification.

Fig. 11 is a diagram showing a cooling device according to a second modification.

Fig. 12 is a flowchart showing a process until the first substrate with the modified surface is carried out to the atmospheric transport region according to the second modification.

Detailed Description

In the following, embodiments of the present disclosure are explained with reference to the drawings. Note that the same or corresponding structures are denoted by the same or corresponding reference numerals in the drawings, and description thereof is sometimes omitted. In this specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are directions perpendicular to each other. The X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction.

Fig. 1 is a plan view showing a joining system according to an embodiment. In fig. 1, the surface hydrophilization apparatus 35 shown in fig. 2 is omitted in order to illustrate the positional relationship among the load lock apparatus 31, the vacuum transfer area 32, and the surface modification apparatus 33. Fig. 2 is a front view showing a joining system according to an embodiment. In fig. 2, the joining apparatus 41 shown in fig. 1 is omitted in order to show the positional relationship among the load lock apparatus 31, the vacuum transfer area 32, the surface modification apparatus 33, and the surface hydrophilization apparatus 35. Fig. 3 is a side view showing a state before the first substrate and the second substrate are bonded according to the embodiment. Fig. 4 is a side view showing a state after the first substrate and the second substrate are bonded according to the embodiment. The bonding system 1 shown in fig. 1 forms a stacked substrate T by bonding a first substrate W1 and a second substrate W2.

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 first substrate W1 has a plurality of metal layers W1a on a bonding surface W1j to which the second substrate W2 is bonded. For example, more than one metal layer W1a is formed for each electronic circuit. The second substrate W2 has a plurality of metal layers W2a on a bonding surface W2j bonded to the first substrate W1. The metal layers W2a are formed in the same number as the metal layers W1a, for example. The first substrate W1 and the second substrate W2 were bonded so that the metal layer W1a was electrically connected to the metal layer W2 a. The metal layer W1a and the metal layer W2a are formed of, for example, copper (Cu), aluminum (Al), tungsten (W), titanium (Ti), ruthenium (Ru), or the like. The first and second substrates W1 and W2 have substantially the same diameter.

Hereinafter, the first substrate W1, the second substrate W2, and the stacked substrate T may be referred to as "upper wafer W1", lower wafer W2 ", and stacked wafer T", respectively. As shown in fig. 3, the surface of the upper wafer W1 on the side to be bonded to the lower wafer W2 is referred to as "bonding surface W1 j", and the surface opposite to the bonding surface W1j is referred to as "non-bonding surface W1 n". Among the plate surfaces of the lower wafer W2, the plate surface on the side to be bonded to the upper wafer W1 is referred to as "bonding surface W2 j", and the plate surface on the side opposite to the bonding surface W2j is referred to as "non-bonding surface W2 n".

As shown in fig. 1, the bonding system 1 includes a loading/unloading station 2 and a processing station 3. The loading/unloading station 2 and the processing stations 3 are arranged in the order of the loading/unloading station 2 and the processing stations 3 in the X-axis positive direction. The loading/unloading station 2 is connected to the processing station 3 integrally.

The loading/unloading station 2 includes a mounting table 10 and a conveying area 20. The mounting table 10 includes a plurality of mounting plates 11. Cassettes CS1, CS2, and CS3 for horizontally storing a plurality of (e.g., 25) substrates are placed on the respective placement plates 11. For example, cassette CS1 is a cassette that accommodates upper wafer W1, cassette CS2 is a cassette that accommodates lower wafer W2, and cassette CS3 is a cassette that accommodates stacked wafers T.

The conveyance area 20 is disposed adjacent to the mounting table 10 on the positive X-axis direction side of the mounting table 10. The conveyance area 20 is provided with a conveyance path 21 extending in the Y-axis direction and a conveyance device 22 movable along the conveyance path 21. The transfer device 22 is movable not only in the Y-axis direction but also in the X-axis direction, and is rotatable about the Z-axis, and transfers the upper wafer W1, the lower wafer W2, and the stacked wafer T between cassettes CS1 to CS3 placed on the mounting plate 11 and a third process block G3 of the process station 3 described later.

The number of cartridges CS1 to CS3 mounted on the mounting plate 11 is not limited to the number shown in the figure. In addition to the cassettes CS1, CS2, and CS3, a cassette for collecting defective substrates and the like may be placed on the placement plate 11.

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

As shown in fig. 1, the atmospheric transport region 60 is formed in a region surrounded by the first process block G1, the second process block G2, and the third process block G3. The atmospheric air transfer area 60 is filled with atmospheric air at normal pressure. The normal pressure includes not only a pressure completely corresponding to the atmospheric pressure but also a pressure corresponding to the atmospheric pressure within a miscalculated range (for example, ± 10 kPa). An atmospheric conveyance device 61 is disposed in the atmospheric conveyance region 60. The atmospheric transport device 61 includes, for example, a transport arm that is movable in the vertical direction, the horizontal direction, and around the vertical axis. The atmospheric transport device 61 moves within the atmospheric transport region 60 to transport the upper wafer W1, the lower wafer W2, and the stacked wafer T to predetermined devices in the first process block G1, the second process block G2, and the third process block G3 adjacent to the atmospheric transport region 60.

In the first process block G1, the load lock apparatus 31, the vacuum transfer area 32, the surface modification apparatus 33, and the surface hydrophilization apparatus 35 are disposed. The load-lock apparatus 31, the vacuum transfer area 32, and the surface modification apparatus 33 are arranged in the negative X-axis direction in this order, for example, as shown in fig. 1 and 2. As shown in fig. 2, the surface hydrophilization apparatus 35 is disposed above the load lock 31, the vacuum transfer area 32, and the surface modification apparatus 33, for example. The type and arrangement of the devices arranged in the first processing block G1 are not particularly limited. For example, the surface hydrophilization device 35 may be disposed under the load lock 31, the vacuum transfer area 32, and the surface modification device 33.

Fig. 5 is a diagram showing a load-lock apparatus and a cooling apparatus according to an embodiment. The position of the first gate valve 111 shown by a solid line in fig. 5 indicates a position for closing the first conveyance port 101, and the position of the first gate valve 111 shown by a two-dot chain line in fig. 5 indicates a position for opening the first conveyance port 101. Similarly, the position of the second gate valve 112 shown by a solid line in fig. 5 represents the position for closing the second conveying port 102, and the position of the second gate valve 112 shown by a two-dot chain line in fig. 5 represents the position for opening the second conveying port 102.

The load lock apparatus 31 forms a load lock chamber 100 for switching the atmospheric pressure in the middle of the transfer path for transferring the upper wafer W1 and the lower wafer W2 between the atmospheric transfer region 60 and the surface modification apparatus 33. The load lock apparatus 31 includes a first transfer port 101, a second transfer port 102, a first gate valve 111, a second gate valve 112, a substrate holder 120, and a gas suction unit 130.

The first transfer port 101 connects the load-lock chamber 100 and the atmospheric transfer region 60. The second transfer port 102 connects the load-lock chamber 100 and the vacuum transfer area 32. The first gate valve 111 opens and closes the first transfer port 101. The second gate valve 112 opens and closes the second transfer port 102.

The substrate holder 120 holds an upper wafer W1 and a lower wafer W2 inside the load-lock chamber 100. The substrate holding unit 120 includes, for example, a plurality of placement units 121 that support the outer peripheral portions of the upper wafer W1 and the lower wafer W2 from below at a plurality of points spaced apart in the circumferential direction. The substrate holding unit 120 horizontally holds the upper wafer W1 from below so that the bonding surface W1j of the upper wafer W1 faces upward. Similarly, the substrate holding unit 120 horizontally holds the lower wafer W2 from below so that the bonding surface W2j of the lower wafer W2 faces upward.

The substrate holding portions 120 are provided in plurality at intervals in the vertical direction, for example. For example, the lower substrate holding unit 120 holds the upper wafer W1 and the lower wafer W2 before the modification by the surface modification apparatus 33. On the other hand, the upper substrate holding unit 120 holds the upper wafer W1 and the lower wafer W2 modified by the surface modification device 33. In fig. 5, a plurality of substrate holding portions 120 are provided at intervals in the vertical direction, but a plurality of substrate holding portions may be provided at intervals in the horizontal direction.

The gas suction portion 130 sucks the gas inside the load-lock chamber 100. The gas suction unit 130 includes, for example, a suction pump 131, a suction line 132, a pressure controller 133, and an opening/closing valve 134. The suction pump 131 sucks the gas inside the load-lock chamber 100. A suction line 132 connects the load-lock chamber 100 and the suction pump 131. The pressure controller 133 is provided in the middle of the suction line 132, and adjusts the air pressure inside the load-lock chamber 100 under the control of the control device 70. The on-off valve 134 is provided in the middle of the suction line 132, and is used to open and close the suction line 132 under the control of the control device 70. When the opening/closing valve 134 opens the suction line 132, the suction pump 131 sucks the gas. On the other hand, when the opening/closing valve 134 closes the suction line 132, the suction pump 131 stops sucking the gas.

When the gas suction unit 130 sucks the gas inside the load-lock chamber 100 in a state where the first gate valve 111 closes the first transfer port 101 and the second gate valve 112 closes the second transfer port 102, the atmosphere in the load-lock chamber 100 becomes a reduced-pressure atmosphere having a pressure lower than the normal pressure. The pressure of the reduced pressure atmosphere is, for example, 1kPa or less. On the other hand, when the first gate valve 111 opens the first transfer port 101, the atmospheric transfer area 60 communicates with the load-lock chamber 100 via the first transfer port 101, and the atmosphere in the load-lock chamber 100 becomes the atmospheric atmosphere at the normal pressure. Before the atmosphere in the load-lock chamber 100 is switched from the reduced-pressure atmosphere to the atmospheric atmosphere at the normal pressure, the second gate valve 112 closes the second transfer port 102. Only when the atmosphere in the load-lock chamber 100 is a reduced pressure atmosphere, the second gate valve 112 opens the second transfer port 102.

The vacuum transfer area 32 is an area maintained in a reduced pressure atmosphere. The pressure of the reduced pressure atmosphere is, for example, 1kPa or less. As shown in fig. 2, the bonding system 1 includes a gas suction unit 140 for sucking the gas inside the vacuum transfer area 32. The gas suction unit 140 includes, for example, a suction pump 141, a suction line 142, a pressure controller 143, and an opening/closing valve 144. The suction pump 141 sucks the gas inside the vacuum transfer area 32. The suction line 142 connects the vacuum transfer area 32 and the suction pump 141. The pressure controller 143 is provided in the middle of the suction line 142, and adjusts the gas pressure inside the vacuum transfer area 32 under the control of the control device 70. The on-off valve 144 is provided in the middle of the suction line 142, and is used to open and close the suction line 142 under the control of the control device 70. When the opening/closing valve 144 opens the suction line 142, the suction pump 141 sucks the gas. On the other hand, when the opening/closing valve 144 closes the suction line 142, the suction pump 141 stops sucking the gas.

As shown in fig. 1, a vacuum transfer device 36 is disposed in the vacuum transfer area 32. The vacuum transfer device 36 includes, for example, a transfer arm that is movable in the vertical direction, the horizontal direction, and around the vertical axis. The vacuum transfer device 36 moves within the vacuum transfer area 32 to transfer the upper wafer W1 and the lower wafer W2 to the load lock 31 and the surface modification device 33.

The surface modification apparatus 33 modifies the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 under a reduced pressure atmosphere while heating them. The pressure of the reduced pressure atmosphere is, for example, 1kPa or less. For example, the surface modification apparatus 33 modifies SiO in the bonding surfaces W1j and W2j₂The bonding surfaces W1j and W2j are modified to be easily hydrophilized thereafter by cutting the bonds to form single-bond SiO.

In the surface modification apparatus 33, for example, nitrogen gas as a processing gas is excited in a reduced pressure atmosphere to be converted into plasma and ionized. Then, the bonding surfaces W1j and W2j are modified by plasma treatment by irradiating the nitrogen ions to the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2.

In addition, the surface modification apparatus 33 heats the upper wafer W1 and the lower wafer W2 to activate the process gas. The heating temperature of the upper wafer W1 and the lower wafer W2 is, for example, 70 ℃. Since the upper wafer W1 and the lower wafer W2 immediately after the surface modification are at a high temperature, when they are carried out from the load lock chamber 100 to the atmospheric transfer region 60, the upper wafer W1 and the lower wafer W2 are oxidized by the atmosphere. More specifically, the oxide film is formed on the surfaces of the metal layer W1a and the metal layer W2 a. The oxide film causes poor conduction between the metal layer W1a and the metal layer W2 a.

Therefore, as shown in fig. 5, the bonding system 1 of the present embodiment includes a cooling device 200, and the cooling device 200 cools the upper wafer W1 and the lower wafer W2 before the modified upper wafer W1 and the modified lower wafer W2 are carried out from the load lock chamber 100 to the atmospheric transfer region 60. Since the upper wafer W1 and the lower wafer W2 are exposed to the atmosphere after the upper wafer W1 and the lower wafer W2 are cooled by the cooling apparatus 200, the formation of oxide films on the surfaces of the metal layer W1a and the metal layer W2a can be suppressed.

The cooling apparatus 200 cools the upper wafer W1 and the lower wafer W2 to a temperature lower than 70 ℃ in a case where the metal layer W1a and the metal layer W2a are formed of copper. This is because the formation of the oxide film rapidly proceeds when copper is exposed to the atmosphere at a temperature of 70 ℃ or higher. When the upper wafer W1 and the lower wafer W2 are exposed to the atmosphere after the upper wafer W1 and the lower wafer W2 are cooled to a temperature lower than 70 ℃, it is possible to suppress the formation of oxide films on the surfaces of the metal layer W1a made of copper and the metal layer W2a made of copper.

The cooling apparatus 200 includes, for example, an internal cooling unit 201, and the internal cooling unit 201 cools the modified upper wafer W1 and the modified lower wafer W2 in the interior of the load lock chamber 100. Since the upper wafer W1 and the lower wafer W2 are cooled inside the load-lock chamber 100, a dedicated area for cooling the upper wafer W1 and the lower wafer W2 is not required, and the size of the bonding system 1 can be suppressed from increasing.

The internal cooling unit 201 includes, for example, an inert gas supply unit 210 that supplies an inert gas into the load lock chamber 100. The inert gas cools the upper wafer W1 and the lower wafer W2 by absorbing heat of the upper wafer W1 and the lower wafer W2 inside the load-lock chamber 100. As the inert gas, for example, nitrogen gas, a rare gas, or the like is used. As the rare gas, argon gas is exemplified.

The inert gas supply unit 210 supplies an inert gas to the inside of the load-lock chamber 100 to return the gas pressure inside the load-lock chamber 100 to the same normal pressure as the gas pressure in the atmospheric transport region 60. Since there is no difference in atmospheric pressure between the load-lock chamber 100 and the atmospheric transfer area 60, it is possible to suppress the introduction of the atmospheric air from the atmospheric transfer area 60 into the load-lock chamber 100 when the first gate valve 111 opens the first transfer port 101.

The inert gas supply unit 210 supplies the inert gas to the interior of the load-lock chamber 100 for a set time even after the gas pressure in the interior of the load-lock chamber 100 reaches the normal pressure. Further, the gas suction unit 130 sucks the inert gas loaded into the interlock chamber 100 during the above-described set time. By sucking the inert gas, the pressure inside the load-lock chamber 100 can be maintained at normal pressure. Further, since heat can be exhausted to the outside by sucking the inert gas, the upper wafer W1 and the lower wafer W2 can be further cooled.

For example, as shown in fig. 5, the inert gas supply unit 210 includes a gas supply line 211, a diffuser 212, a nozzle 213, an on-off valve 214, a flow rate controller 215, and a filter 216. The inert gas supply unit 210 may further include a gas cooling mechanism 217.

A gas supply line 211 connects a supply of inert gas to the load-lock chamber 100. The gas supply line 211 includes a common line 211a extending from a supply source of the inert gas, and a plurality of branch lines 211b and 211c extending from a downstream end portion of the common line 211 a.

The diffuser 212 is provided at a downstream end portion of one branch line 211b for diffusively injecting the inactive gas into the interior of the load-lock chamber 100. The supply port 212a of the diffuser 212 for supplying the inert gas is formed of, for example, a porous material. The injection from the diffuser 212 is performed mainly before the air pressure inside the load-lock chamber 100 is returned to the normal pressure. The diffuser 212 may have a supply port 212a for supplying an inert gas at a position not facing a substrate (e.g., the upper wafer W1 or the lower wafer W2) housed in the load-lock chamber 100. That is, the center line FL1 of the inert gas flow supplied from the supply port 212a does not intersect the substrate but deviates from the substrate.

On the other hand, the nozzle 213 is provided at the downstream end of the other branch line 211c, and injects an inert gas toward the upper wafer W1 and the lower wafer W2 held by the substrate holding unit 120. The ejection from the nozzle 213 is performed mainly while the air pressure inside the load lock chamber 100 is maintained at the normal pressure.

The nozzle 213 may have a supply port 213a for supplying an inert gas at a position facing a substrate (e.g., the upper wafer W1 or the lower wafer W2) accommodated in the load lock chamber 100. That is, the center line FL2 of the inert gas flow supplied from the supply port 213a may intersect the substrate. The centerline FL2 intersects the faying surfaces W1j, W2 j. The nozzle 213 injects the inert gas toward the center portions of the bonding surfaces W1j and W2j from above, for example. The injected inert gas hits the central portions of the bonding surfaces W1j and W2j, and then spreads concentrically outward in the radial direction. By forming the concentrically expanding airflow, the entire bonding surfaces W1j, W2j can be uniformly cooled.

Further, the ejection direction of the nozzle 213 is not particularly limited. The center line LF2 may intersect the substrate, or may intersect the non-bonding surfaces W1n, W2n instead of intersecting the bonding surfaces W1j, W2 j. For example, the nozzle 213 may inject the inert gas from below toward the center of the non-joint surfaces W1n and W2 n. The injected inert gas hits the center portions of the non-joint surfaces W1n and W2n and then spreads concentrically outward in the radial direction. By forming the concentrically-expanding airflow, the entire non-joint surfaces W1n, W2n can be uniformly cooled, and further, the entire joint surfaces W1j, W2j can be uniformly cooled. The ejection direction of the nozzle 213 may be a horizontal direction instead of a vertical direction. The number of nozzles 213 is not limited to one, and may be plural.

The on-off valve 214 opens and closes the gas supply line 211 under the control of the control device 70. When the open-close valve 214 opens the gas supply line 211, the inert gas is supplied to the inside of the load-lock chamber 100. On the other hand, when the on-off valve 214 closes the gas supply line 211, the supply of the inert gas to the inside of the load-lock chamber 100 is stopped. The flow controller 215 adjusts the flow rate of the inert gas under the control of the control device 70. The filter 216 cleans the inactive gas. An opening and closing valve 214, a flow rate controller 215, and a filter 216 are provided for each of the branch lines 211b, 211 c.

The gas cooling mechanism 217 is used to cool the inert gas before being supplied to the interior of the load-lock chamber 100. The inactive gas is cooled to a temperature lower than room temperature. By cooling the inert gas in advance, the heat absorption of the inert gas can be improved, and the time required for cooling the upper wafer W1 and the lower wafer W2 can be shortened. When the inert gas is cooled in advance, the set time may be set to zero.

Fig. 6 is a flowchart showing a process up to the modification of the surface of the first substrate according to one embodiment. Fig. 7 is a flowchart showing a process until the first substrate with the modified surface is carried out to the atmospheric transfer area according to one embodiment. Regarding the processing of the upper wafer W1 shown in fig. 6 and 7, the processing is repeatedly performed by replacing the upper wafer W1 under the control of the controller 70. The lower wafer W2 is processed in the same manner as the upper wafer W1 shown in fig. 6 and 7.

First, when the atmospheric transfer device 61 transfers the upper wafer W1 to the front of the first transfer port 101, the first gate valve 111 opens the first transfer port 101 (S101). At this time, the second gate valve 112 closes the second transfer port 102, and the third gate valve 113 closes the third transfer port 103. The third conveyance port 103 is formed in the surface modification apparatus 33.

Next, the atmospheric transfer device 61 transfers the upper wafer W1 to the interior of the load-lock chamber 100 through the first transfer port 101 (S102). After that, when the substrate holder 120 receives the upper wafer W1 from the atmospheric transfer device 61, the atmospheric transfer device 61 exits from the load lock chamber 100 to the atmospheric transfer area 60 through the first transfer port 101. Next, the first gate valve 111 closes the first conveying port 101 (S103).

Next, the gas suction unit sucks the gas inside the load-lock chamber 100 to reduce the pressure inside the load-lock chamber 100 (S104). When the air pressure inside the load-lock chamber 100 is about the same as the air pressure in the vacuum transfer area 32, the second gate valve 112 opens the second transfer port 102, and the third gate valve 113 opens the third transfer port 103 (S105).

Next, the vacuum transfer device 36 transfers the upper wafer W1 from the load lock chamber 100 to the inside of the surface modification apparatus 33 (S106). After that, when the suction pads of the surface modification apparatus 33 receive the upper wafer W1 from the vacuum transfer apparatus 36, the vacuum transfer apparatus 36 is retracted from the inside of the surface modification apparatus 33 to the vacuum transfer area 32 through the third transfer port 103. Next, the second gate valve 112 closes the second conveying port 102, and the third gate valve 113 closes the third conveying port 103 (S107). The timing at which the second gate valve 112 closes the second transfer port 102 may be after the vacuum transfer device 36 has exited from the interior of the load-lock chamber 100 to the vacuum transfer area 32.

Next, the surface modification apparatus 33 modifies the bonding surface W1j of the upper wafer W1 while heating the bonding surface in a reduced pressure atmosphere (S108). Thereafter, the second gate valve 112 opens the second transfer port 102, and the third gate valve 113 opens the third transfer port 103 (S109).

Next, the vacuum transfer device 36 transfers the upper wafer W1 from the inside of the surface modification device 33 to the load lock chamber 100 (S110). The atmosphere in the load-lock chamber 100 at this time is a reduced-pressure atmosphere. After that, when the substrate holder 120 receives the upper wafer W1 from the vacuum transfer device 36, the vacuum transfer device 36 is retracted from the load-lock chamber 100 to the vacuum transfer area 32 through the second transfer port 102. Next, the second gate valve 112 closes the second conveying port 102, and the third gate valve 113 closes the third conveying port 103 (S111). The timing at which the third gate valve 113 closes the third transfer port 103 may be after the vacuum transfer device 36 has retreated from the inside of the surface modification device 33 to the vacuum transfer area 32.

Next, the inert gas supply unit 210 supplies an inert gas to the inside of the load-lock chamber 100 (S112). The inert gas cools the upper wafer W1 by absorbing heat of the upper wafer W1 inside the load-lock chamber 100. Thereafter, the first gate valve 111 opens the first transfer port 101 (S113).

Next, the atmospheric transfer device 61 transfers the upper wafer W1 from the load lock chamber 100 to the atmospheric transfer area 60 (S114). When the atmospheric conveyance device 61 is retracted to the atmospheric conveyance region 60, the first gate valve 111 closes the first conveyance port 101 (S115). After that, the air transport device 61 transports the upper wafer W1 to the surface hydrophilization device 35.

As described above, the load-lock chamber 100 for switching the atmospheric pressure is formed in the middle of the transfer path for transferring the upper wafer W1 and the lower wafer W2. This can maintain the atmosphere inside the surface modification apparatus 33 at a reduced pressure. Therefore, the step of switching the atmosphere inside the surface modification apparatus 33 between the reduced pressure atmosphere and the atmospheric atmosphere at normal pressure can be omitted.

The cooling apparatus 200 cools the upper wafer W1 and the lower wafer W2 before the upper wafer W1 and the lower wafer W2 are carried out from the load lock chamber 100 to the atmospheric transfer region 60. Since the upper wafer W1 and the lower wafer W2 are exposed to the atmosphere after the upper wafer W1 and the lower wafer W2 are cooled by the cooling apparatus 200, the formation of oxide films on the surfaces of the metal layer W1a and the metal layer W2a can be suppressed.

In the present embodiment, the cooling apparatus 200 cools both the upper wafer W1 and the lower wafer W2, but may cool only either one of them. If the oxide film can be prevented from being formed on the surface of either one of the metal layer W1a and the metal layer W2a, the conduction failure between the metal layer W1a and the metal layer W2a can be prevented.

The surface hydrophilizing apparatus 35 hydrophilizes the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 with pure water, for example. The surface hydrophilizing apparatus 35 also has a function of cleaning the joint surfaces W1j and W2 j. In the surface hydrophilization apparatus 35, 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. Thus, pure water supplied to 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 hydrophilizes the bonding surfaces W1j and W2 j.

At a second processing block G2, a bonding device 41 is arranged. The bonding apparatus 41 bonds the upper wafer W1 and the lower wafer W2 by opposing the bonding surface W1j of the hydrophilized upper wafer W1 and the bonding surface W2j of the hydrophilized lower wafer W2. The upper wafer W1 and the lower wafer W2 are bonded to each other by electrically connecting the metal layers W1a and W2 a. The type and arrangement of the devices arranged in the second processing block G2 are not particularly limited.

As shown in fig. 2, the transfer devices 50, 51 are arranged in a third processing block G3. The transfer device 50 temporarily stores the upper wafer W1 and the lower wafer W2. The transfer device 51 temporarily stores the stacked wafers T. The plurality of conveyors 50, 51 are stacked in the vertical direction. The type and arrangement of the devices arranged in the third processing block G3 are not particularly limited.

As shown in fig. 1, the joining system 1 includes a control device 70. The control device 70 is constituted by a computer, for example, and includes a CPU (Central Processing Unit) 71 and a storage medium 72 such as a memory. A program for controlling various processes executed in the joining system 1 is stored in the storage medium 72. The control device 70 controls the operation of the joining system 1 by causing the CPU 71 to execute a program stored in the storage medium 72. The control device 70 includes an input interface 73 and an output interface 74. The control device 70 receives a signal from the outside through the input interface 73 and transmits a signal to the outside through the output interface 74.

The program of the control device 70 is stored in a computer-readable storage medium, for example, and is installed from the storage medium. Examples of the computer-readable storage medium include a Hard Disk (HD), a Flexible Disk (FD), an optical disk (CD), a magneto-optical disk (MO), and a memory card. Further, the program of the control device 70 may be downloaded from a server via the internet.

Fig. 8 is a flowchart showing the main steps of the bonding method according to the embodiment. Further, various processes shown in fig. 8 are executed under the control of the control device 70. First, the cassette CS1 containing the plurality of upper wafers W1, the cassette CS2 containing the plurality of lower wafers W2, and the empty cassette CS3 are placed on a predetermined mounting plate 11 of the loading/unloading station 2.

Next, the transfer device 22 takes out the upper wafer W1 in the cassette CS1 and transfers it to the transfer device 50. Next, the atmospheric transfer device 61 receives the upper wafer W1 from the transfer device 50 and transfers it to the load lock chamber 100. Thereafter, the vacuum transfer device 36 transfers the upper wafer W1 from the load lock chamber 100 to the surface modification device 33.

Next, the surface modification apparatus 33 modifies the bonding surface W1j of the upper wafer W1 while heating the same in a reduced pressure atmosphere (S201). In the surface modification apparatus 33, nitrogen gas as a processing gas is excited in a reduced pressure atmosphere to be converted into plasma and ionized. The nitrogen ions are irradiated to the bonding surface W1j of the upper wafer W1, and the plasma processing is performed on the bonding surface W1 j. This modifies the bonding surface W1j of the upper wafer W1. Thereafter, the vacuum transfer device 36 transfers the upper wafer W1 from the surface modification device 33 to the load lock chamber 100.

Next, the cooling apparatus 200 cools the upper wafer W1 before the upper wafer W1 is carried out from the load lock chamber 100 to the atmospheric transfer region 60 (S202). Since the upper wafer W1 is exposed to the atmosphere after cooling the upper wafer W1, the formation of an oxide film on the surface of the metal layer W1a can be suppressed. Thereafter, the atmospheric transport device 61 transports the upper wafer W1 to the surface hydrophilization device 35 via the atmospheric transport region 60.

Subsequently, the surface hydrophilizing apparatus 35 hydrophilizes the bonding surface W1j of the upper wafer W1 (S203). In the surface hydrophilization apparatus 35, pure water is supplied onto the upper wafer W1 while the upper wafer W1 held by the spin chuck is rotated. Then, the supplied pure water diffuses on the bonding surface W1j of the upper wafer W1, and hydroxyl groups (silanol groups) adhere to the bonding surface W1j of the upper wafer W1 modified by the surface modifying apparatus 33 to hydrophilize the bonding surface W1 j. The bonding surface W1j of the upper wafer W1 is cleaned with pure water for hydrophilization of the bonding surface W1 j. After that, the atmospheric transfer device 61 transfers the upper wafer W1 to the bonding device 41.

The bonding apparatus 41 turns the upper wafer W1 upside down to direct the bonding surface W1j of the upper wafer W1 downward (S204). While the process of the upper wafer W1 (S201 to S204 described above) is performed, the process of the lower wafer W2 (S205 to S207 described below) is performed.

First, the transfer device 22 takes out the lower wafer W2 in the cassette CS2 and transfers it to the transfer device 50. Next, the atmospheric transfer device 61 receives the lower wafer W2 from the transfer device 50 and transfers it to the load lock chamber 100. Thereafter, the vacuum transfer device 36 transfers the lower wafer W2 from the load lock chamber 100 to the surface modification device 33.

Next, the surface modification apparatus 33 modifies the bonding surface W2j of the lower wafer W2 while heating the same in a reduced pressure atmosphere (S205). The joining surface W2j is modified (S205) in the same manner as the modification of the joining surface W1j (S201). Thereafter, the vacuum transfer device 36 transfers the lower wafer W2 from the surface modification device 33 to the load lock chamber 100.

Next, the cooling apparatus 200 cools the lower wafer W2 before the lower wafer W2 is carried out from the load lock chamber 100 to the atmospheric transfer region 60 (S206). Since the lower wafer W2 is exposed to the atmosphere after the lower wafer W2 is cooled, the formation of an oxide film on the surface of the metal layer W2a can be suppressed. Thereafter, the atmospheric transport device 61 transports the lower wafer W2 to the surface hydrophilization apparatus 35 via the atmospheric transport region 60.

Subsequently, the surface hydrophilizing apparatus 35 hydrophilizes the bonding surface W2j of the lower wafer W2 (S207). The hydrophilization (S207) of the bonding surface W2j is performed in the same manner as the hydrophilization (S203) of the bonding surface W1 j. Thereafter, the atmospheric transport device 61 transports the lower wafer W2 to the bonding apparatus 41.

Next, the bonding apparatus 41 bonds the upper wafer W1 and the lower wafer W2 by opposing the bonding surface W1j of the upper wafer W1 to the bonding surface W2j of the lower wafer W2 (S208). Since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are modified in advance, van der waals forces (intermolecular forces) are generated between the bonding surfaces W1j and W2j, and the bonding surfaces W1j and W2j are bonded to each other. Since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are hydrophilized in advance, the hydrophilic groups between the bonding surfaces W1j and W2j are hydrogen-bonded, and the bonding surfaces W1j and W2j are strongly bonded to each other.

Thereafter, the atmospheric transfer device 61 transfers the stacked wafer T to the transfer device 51. Thereafter, the transfer device 22 receives the stacked wafer T from the transfer device 51 and transfers it to the cassette CS 3. Thus, the series of processes ends.

Fig. 9 is a diagram showing a load-lock apparatus and a cooling apparatus according to a first modification. The position of the first gate valve 111 shown by a solid line in fig. 9 indicates a position for closing the first conveyance port 101, and the position of the first gate valve 111 shown by a two-dot chain line in fig. 9 indicates a position for opening the first conveyance port 101. Similarly, the position of the second gate valve 112 shown by a solid line in fig. 9 represents the position for closing the second conveying port 102, and the position of the second gate valve 112 shown by a two-dot chain line in fig. 9 represents the position for opening the second conveying port 102. The internal cooling portion 201 of the present modification includes, for example, a temperature adjustment plate portion 220 and a coolant supply portion 230 in addition to the inactive gas supply portion 210.

The temperature adjustment plate portion 220 is disposed inside the load-lock chamber 100 to adjust the temperature of the upper wafer W1 and the lower wafer W2 held by the substrate holding portion 120. The temperature adjustment plate portion 220 is horizontally disposed above the upper wafer W1 and the lower wafer W2 so as to face the upper wafer W1 and the lower wafer W2. The temperature control plate portion 220 is formed in a disk shape, and the diameter of the temperature control plate portion 220 is larger than the diameters of the upper wafer W1 and the lower wafer W2. A flow path for the refrigerant is formed inside the temperature adjustment plate portion 220.

The coolant supply unit 230 supplies coolant to the internal flow path of the temperature adjustment plate unit 220 to maintain the temperature of the temperature adjustment plate unit 220 at the temperature of the coolant. The temperature of the refrigerant is, for example, room temperature or lower, preferably lower than room temperature. The refrigerant absorbs heat of the temperature adjustment plate portion 220 and is discharged to the outside of the temperature adjustment plate portion 220. After that, the refrigerant may also flow back to the refrigerant supply portion 230.

For example, the refrigerant supply unit 230 includes a refrigerant supply line 231, an opening/closing valve 232, a flow rate controller 233, and a filter 234. The coolant supply line 231 connects the coolant supply source to the temperature adjustment panel portion 220. The opening/closing valve 232 opens and closes the refrigerant supply line 231 under the control of the control device 70. When the opening/closing valve 232 opens the refrigerant supply line 231, the refrigerant is supplied from the supply source to the temperature adjustment plate portion 220. On the other hand, when the opening/closing valve 232 closes the refrigerant supply line 231, the supply of the refrigerant from the supply source to the temperature adjustment plate portion 220 is stopped. The flow rate controller 233 adjusts the flow rate of the refrigerant under the control of the control device 70. The filter 234 cleans the refrigerant.

According to the present modification, the heat of the upper wafer W1 and the lower wafer W2 can be absorbed by the temperature-regulating plate portion 220 to cool the upper wafer W1 and the lower wafer W2. When a gap is formed between the upper wafer W1, the lower wafer W2, and the temperature-regulating plate portion 220, the inert gas supply portion 210 supplies an inert gas into the load-lock chamber 100 so that the gap is filled with the inert gas. This promotes heat transfer from the upper wafer W1 and the lower wafer W2 to the temperature control plate portion 220.

The internal cooling portion 201 of the present modification includes a space changing portion 240 in addition to the temperature adjustment plate portion 220 and the refrigerant supply portion 230. The gap changing unit 240 changes the gap between the upper wafer W1 and the lower wafer W2 and the temperature-adjusting plate unit 220. The closer the distance is, the more easily the heat of the upper wafer W1 and the lower wafer W2 is transmitted to the temperature adjustment plate portion 220. Therefore, the temperatures of the upper wafer W1 and the lower wafer W2 can be adjusted by changing the interval.

The interval changing unit 240 changes the interval between the temperature control panel unit 220 and the upper wafer W1 and the lower wafer W2 by moving the temperature control panel unit 220 up and down. The interval changing unit 240 includes, for example, a rotary motor and a ball screw for converting the rotary motion of the rotary motor into the linear motion of the temperature adjustment plate unit 220. The structure of the interval changing section 240 is not particularly limited. For example, the interval changing unit 240 may be a pneumatic cylinder.

The arrangement of the temperature adjustment plate portion 220 is not particularly limited. For example, there may be no gap between the upper wafer W1 and the lower wafer W2 and the temperature-adjusting plate portion 220. That is, the temperature control plate portion 220 may contact the upper wafer W1 and the lower wafer W2. In this case, the temperature control plate portion 220 can absorb heat of the upper wafer W1 and the lower wafer W2 even without the inert gas supply portion 210. The temperature control plate portion 220 may be disposed horizontally below the upper wafer W1 and the lower wafer W2.

Fig. 10 is a plan view showing a bonding system according to a second modification. Fig. 11 is a diagram showing a cooling device according to a second modification. The position of the fourth gate valve 114 shown by a solid line in fig. 11 indicates a position for closing the fourth conveying port 104, and the position of the fourth gate valve 114 shown by a two-dot chain line in fig. 11 indicates a position for opening the fourth conveying port 104.

The bonding system 1 of the present modification is different from the bonding system 1 of the above embodiment in that the cooling device 200 includes the external cooling unit 202. The external cooling unit 202 cools the modified upper wafer W1 and the modified lower wafer W2 outside the load-lock chamber 100. The following mainly explains the difference.

As shown in fig. 10, the vacuum transfer area 32 is adjacent to the external cooling unit 202, the load-lock apparatus 31, and the surface modification apparatus 33. The external cooling unit 202, the load-lock apparatus 31, and the surface modification apparatus 33 surround the vacuum transfer area 32 from three directions. The external cooling unit 202 is disposed on the positive Y-axis side of the vacuum transfer area 32, the load lock 31 is disposed on the positive X-axis side of the vacuum transfer area 32, and the surface modification device 33 is disposed on the negative X-axis side of the vacuum transfer area 32.

The external cooling unit 202 cools the modified upper wafer W1 and the modified lower wafer W2 outside the load-lock chamber 100 as described above. As shown in fig. 11, the external cooling unit 202 includes a cooling container 250, a gas suction unit 260, a substrate holding unit 270, and a coolant supply unit 280.

The cooling container 250 forms a space inside to cool the upper wafer W1 and the lower wafer W2. The cooling container 250 includes the fourth transfer port 104 and the fourth gate valve 114. The fourth transfer port 104 connects the inside of the cooling container 250 to the vacuum transfer area 32. The fourth gate valve 114 opens and closes the fourth transfer port 104.

The gas suction unit 260 sucks the gas inside the cooling container 250. The gas suction unit 260 includes, for example, a suction pump 261, a suction line 262, a pressure controller 263, and an opening/closing valve 264. The suction pump 261 sucks the gas inside the cooling container 250. The suction line 262 connects the cooling container 250 to the suction pump 261. The pressure controller 263 is provided in the middle of the suction line 262, and adjusts the air pressure inside the cooling container 250 under the control of the control device 70. The on-off valve 264 is provided in the middle of the suction line 262, and is used to open and close the suction line 262 under the control of the control device 70. When the opening/closing valve 264 opens the suction line 262, the suction pump 261 sucks the gas. On the other hand, when the opening/closing valve 264 closes the suction line 262, the suction pump 261 stops sucking the gas. The inside of the cooling container 250 is maintained in a reduced pressure atmosphere. The pressure of the reduced pressure atmosphere is, for example, 1kPa or less.

The substrate holder 270 holds the upper wafer W1 and the lower wafer W2 in the cooling container 250. The substrate holder 270 holds the upper wafer W1 horizontally from below so that the bonding surface W1j of the upper wafer W1 faces upward, for example. Similarly, the substrate holder 270 holds the lower wafer W2 horizontally from below so that the bonding surface W2j of the lower wafer W2 faces upward. The substrate holder 270 is formed in a disk shape, and the diameter of the substrate holder 270 is larger than the diameters of the upper wafer W1 and the lower wafer W2. The substrate holder 270 is in contact with the entire non-bonding surfaces W1n and W2 n. In addition, the number of the substrate holding portions 270 is one in fig. 11, but may be plural. A flow path for the coolant is formed inside the substrate holding portion 270.

The coolant supply unit 280 supplies the coolant to the internal flow path of the substrate holding unit 270 to maintain the temperature of the substrate holding unit 270 at the temperature of the coolant. The temperature of the refrigerant is, for example, room temperature or lower, preferably lower than room temperature. The coolant absorbs heat of the substrate holder 270 and is discharged to the outside of the substrate holder 270. Thereafter, the refrigerant may flow back to the refrigerant supply unit 280.

For example, the refrigerant supply unit 280 includes a refrigerant supply line 281, an opening/closing valve 282, a flow rate controller 283, and a filter 284. The coolant supply line 281 connects a coolant supply source to the substrate holder 270. The opening/closing valve 282 opens/closes the refrigerant supply line 281 under the control of the control device 70. When the opening/closing valve 282 opens the refrigerant supply line 281, the refrigerant is supplied from the supply source to the substrate holding portion 270. On the other hand, when the opening/closing valve 282 closes the refrigerant supply line 281, the supply of the refrigerant from the supply source to the substrate holding portion 270 is stopped. The flow rate controller 283 adjusts the flow rate of the refrigerant under the control of the control device 70. The filter 284 cleans the refrigerant.

According to the present modification, the upper wafer W1 and the lower wafer W2 can be cooled by the substrate holding portion 270 absorbing heat of the upper wafer W1 and the lower wafer W2. Since the substrate holding portion 270 is in contact with the entire non-bonding surfaces W1n and W2n, the entire non-bonding surfaces W1n and W2n can be uniformly cooled, and the entire bonding surfaces W1j and W2j can be uniformly cooled.

In addition, according to the present modification, the vacuum transfer area 32 is adjacent to the external cooling unit 202, the load-lock apparatus 31, and the surface modification apparatus 33. Therefore, while the upper wafer W1 and the lower wafer W2 are cooled by the external cooling unit 202, the vacuum transfer device 36 can transfer the upper wafer W1 and the lower wafer W2 from the load lock 31 to the surface modification device 33. This can improve the overall productivity of the joining system 1.

Fig. 12 is a flowchart showing a process until the first substrate with the modified surface is carried out to the atmospheric transport region according to the second modification. Regarding the processing of the upper wafer W1 shown in fig. 12, the processing is repeatedly performed by replacing the upper wafer W1 under the control of the control device 70. Further, the lower wafer W2 is processed in the same manner as the upper wafer W1 shown in fig. 12.

The surface modification apparatus 33 modifies the bonding surface W1j of the upper wafer W1 while heating the same in a reduced pressure atmosphere (S108 in fig. 6). Thereafter, the third gate valve 113 opens the third transfer port 103, and the fourth gate valve 114 opens the fourth transfer port 104 (S301).

Next, the vacuum transfer device 36 transfers the upper wafer W1 from the inside of the surface modification device 33 to the inside of the cooling container 250 (S302). The atmosphere inside cooling container 250 is maintained at a reduced pressure. After that, when the substrate holder 270 receives the upper wafer W1 from the vacuum transfer device 36, the vacuum transfer device 36 is retracted from the cooling container 250 to the vacuum transfer area 32 through the fourth transfer port 104. Next, the third gate valve 113 closes the third conveying port 103, and the fourth gate valve 114 closes the fourth conveying port 104 (S303). The timing at which the third gate valve 113 closes the third transfer port 103 may be after the vacuum transfer device 36 has retreated from the inside of the surface modification device 33 to the vacuum transfer area 32.

Next, the substrate holder 270 cools the upper wafer W1 in the cooling container 250 (S304). The coolant supply unit 280 supplies a coolant to the internal flow path of the substrate holding unit 270 to cool the upper wafer W1. The substrate holder 270 absorbs heat of the upper wafer W1 to cool the upper wafer W1. Thereafter, the fourth gate valve 114 opens the fourth conveying port 104, and the second gate valve 112 opens the second conveying port 102 (S305).

Next, the vacuum transfer device 36 transfers the upper wafer W1 from the inside of the cooling container 250 to the inside of the load-lock chamber 100 (S306). The atmosphere in the load-lock chamber 100 at this time is a reduced-pressure atmosphere. After that, when the substrate holder 120 receives the upper wafer W1 from the vacuum transfer device 36, the vacuum transfer device 36 is retracted from the load-lock chamber 100 to the vacuum transfer area 32 through the second transfer port 102. Next, the second gate valve 112 closes the second conveying port 102, and the fourth gate valve 114 closes the fourth conveying port 104 (S307). The timing at which the fourth gate valve 114 closes the fourth transfer port 104 may be after the vacuum transfer device 36 has exited from the inside of the cooling container 250 to the vacuum transfer area 32.

Next, the first gate valve 111 opens the first transfer port 101 (S308). Thereby, the atmosphere in the load-lock chamber 100 is switched to the atmospheric atmosphere at normal pressure. Further, the gas supply unit may supply the atmosphere or the inert gas to the inside of the load-lock chamber 100 before the first gate valve 111 opens the first transfer port 101, thereby returning the gas pressure inside the load-lock chamber 100 to the normal pressure.

Next, the atmospheric transfer device 61 transfers the upper wafer W1 from the load lock chamber 100 to the atmospheric transfer area 60 (S309). When the atmospheric conveyance device 61 is retracted to the atmospheric conveyance region 60, the first gate valve 111 closes the first conveyance port 101 (S310). After that, the air transport device 61 transports the upper wafer W1 to the surface hydrophilization device 35.

As described above, in the present modification as well, the cooling apparatus 200 cools the upper wafer W1 and the lower wafer W2 before the upper wafer W1 and the lower wafer W2 are carried out from the load-lock chamber 100 to the atmospheric transfer region 60, as in the above-described embodiment. Since the upper wafer W1 and the lower wafer W2 are exposed to the atmosphere after the upper wafer W1 and the lower wafer W2 are cooled by the cooling apparatus 200, the formation of oxide films on the surfaces of the metal layer W1a and the metal layer W2a can be suppressed.

In the present modification, the cooling apparatus 200 cools both the upper wafer W1 and the lower wafer W2, but may cool only either one of them. If the oxide film can be prevented from being formed on the surface of either one of the metal layer W1a and the metal layer W2a, the conduction failure between the metal layer W1a and the metal layer W2a can be prevented.

The embodiments of the joining system and the joining method according to the present disclosure have been described above, but the present disclosure is not limited to the above embodiments and the like. Various changes, modifications, substitutions, additions, deletions, and combinations may be made within the scope of the claims. These also naturally fall within the technical scope of the present disclosure.

In the above embodiment, the first modification example, and the second modification example, the upper wafer W1 corresponds to a first substrate, and the lower wafer W2 corresponds to a second substrate, but the upper wafer W1 may correspond to a second substrate, and the lower wafer W2 may correspond to a second substrate.

The internal cooling unit 201 of the above embodiment, the internal cooling unit 201 of the first modification, and the external cooling unit 202 of the second modification may be used in combination.

The application claims the priority of application No. 2019 and 047586 from 3, 14.2019 to the present patent office, and the entire contents of the application No. 2019 and 047586 are incorporated into the present application.

Description of the reference numerals

1: a joining system; 31: a load interlock; 32: a vacuum transfer area; 33: a surface modification device; 35: a surface hydrophilization device; 41: an engaging device; 60: an atmospheric transport region; 70: a control device; w1: an upper wafer (first substrate); w2: lower wafer (second substrate).