Mounting apparatus and mounting system

A mounting apparatus for stacking and mounting two or more semiconductor chips at a plurality of locations on a substrate includes: a first mounting head for forming, at a plurality of locations on the substrate, temporarily stacked bodies in which two or more semiconductor chips are stacked in a temporarily press-attached state; and a second mounting head for forming chip stacked bodies by sequentially finally press-attaching the temporarily stacked bodies formed at the plurality of locations. The second mounting head includes: a press-attaching tool for heating and pressing an upper surface of a target temporarily stacked body to thereby finally press-attach the two or more semiconductor chips configuring the temporarily stacked body altogether; and one or more heat-dissipation tools having a heat-dissipating body which, by coming into contact with an upper surface of another stacked body positioned around the target temporarily stacked body, dissipates heat from the another stacked body.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 application of an international PCT application serial no. PCT/JP2018/002950, filed on Jan. 30, 2018, which claims the priority benefit of Japan application JP2017-014756, filed on Jan. 30, 2017. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

Technical Field

The present invention relates to a mounting apparatus and a mounting system for stacking and mounting two or more semiconductor chips at a plurality of locations on a substrate.

Related Art

Conventionally, there is a demand for a semiconductor device having higher functionality and a smaller size. Therefore, some documents of literature propose that a plurality of semiconductor chips are stacked and mounted. In general, a bump and a non-conductive film (hereinafter, referred to as the “NCF”) that covers the bump are arranged on one surface of a semiconductor chip. The NCF is made of thermosetting resin and reversibly softens as the temperature increases when the temperature is lower than a predetermined hardening start temperature but irreversibly hardens as the temperature increases when the temperature is higher than the hardening start temperature. In order to stack and mount the semiconductor chips, the following is proposed. A plurality of semiconductor chips are stacked while being temporarily press-attached, and then a stacked body in the temporarily press-attached state is heated and pressed to be finally press-attached. Moreover, hereinafter, the stacked body in the temporarily press-attached state is referred to as a “temporarily stacked body”, and the stacked body after final press-attachment is referred to as a “chip stacked body”. In addition, when there is no need to distinguish between the temporarily stacked body and the chip stacked body, both are simply referred to as the “stacked body”. According to such technologies, it is possible to mount more semiconductor chips in a small area, and thus it is possible to achieve higher functionality and smaller size.

[Literature of Related Art]

Non-Patent Literature 1: “Heat Transfer Analysis in the Thermal Compression Bonding for CoW Process” by Noboru Asahi et al. in ICEP 2016 Proceedings, pp. 640-643

SUMMARY

Problems to be Solved

Meanwhile, a plurality of chip stacked bodies are mounted on one substrate, in general. In a case of mounting the plurality of chip stacked bodies, some documents of literature propose a technology in which a plurality of temporarily stacked bodies are formed, and then the plurality of temporarily stacked bodies are sequentially finally press-attached. According to the corresponding technology, it is possible to reduce the number of times of switching between a temporarily press-attaching process and a finally press-attaching process, and thus it is possible to further simplify and shorten a mounting step, compared with a case in which temporary press-attachment and final press-attachment of one stacked body are completed, and then temporary press-attachment and final press-attachment of the next stacked body are performed.

On the other hand, in a case of a technology in which the final press-attachment is performed after a plurality of temporarily stacked bodies are formed, heat applied to one temporarily stacked body for the final press-attachment is also transmitted to an adjacent temporarily stacked body in some cases. In particular, when the substrate has a high heat transfer rate, the heat for the final press-attachment which is applied to one temporarily stacked body is transmitted to the adjacent temporarily stacked body with high efficiency and brings about an increase in temperature of the temporarily stacked body. In this case, there is a concern that the NCF will irreversibly harden in the other temporarily stacked body. When the NCF hardens before final press-attachment, the semiconductor chip and the substrate are inhibited from being appropriately joined to each other.

Here, Non-Patent Literature 1 proposes a technology in which, when one semiconductor chip is finally press-attached, cooling air is applied to an adjacent semiconductor chip, and thereby an increase in temperature of the adjacent semiconductor chip and eventually hardening of the NCF are prevented. However, in a case of performing cooling with cooling air, a problem arises in that not only cooling efficiency is degraded but also it is difficult to limit a cooling range. As a result, there is a concern that part of the cooling air reaches not only the adjacent semiconductor chip being a cooling target but also an adjacent semiconductor chip being finally press-attached, a temperature of the semiconductor chip being finally press-attached will decrease, and defective mounting will be brought about.

Therefore, an objective of the present invention is to provide a mounting apparatus and a mounting system that is capable of more appropriately mounting semiconductor chips when a plurality of temporary chip stacked bodies are formed and then the temporary chip stacked bodies are sequentially finally press-attached.

Means to Solve Problems

A mounting apparatus of the present invention is a mounting apparatus for stacking and mounting two or more semiconductor chips at a plurality of locations on a substrate, the mounting apparatus including: a temporary press-attachment head for forming, at a plurality of locations on the substrate, temporarily stacked bodies in which two or more semiconductor chips are stacked in a temporarily press-attached state; and a final press-attachment head for forming chip stacked bodies by sequentially finally press-attaching the temporarily stacked bodies formed at the plurality of locations. The final press-attachment head has a press-attaching tool for heating and pressing an upper surface of a target temporarily stacked body to thereby finally press-attach the two or more semiconductor chips configuring the temporarily stacked body altogether, and one or more heat-dissipation tools having a heat-dissipating body which, by coming into contact with upper surfaces of another stacked body positioned around the target temporarily stacked body, dissipates heat from the another stacked body.

According to this configuration, when final press-attachment is performed, the another stacked body positioned around the target stacked body can be pinpointed and cooled, and thus it is possible to prevent an NCF from hardening in the stacked body before the final press-attachment, while preventing a decrease in temperature of the stacked body being finally press-attached.

In addition, the final press-attachment head may further include a base to which the press-attaching tool and the heat-dissipation tools are attached, and the press-attaching tool and the heat-dissipation tools may be lifted and lowered in connection with each other by lifting and lowering the base.

According to this configuration, lifting and lowering of the press-attaching tool and the heat-dissipation tools can be integrally controlled, and thus the control can be simplified.

In addition, in this case, the heat-dissipation tools may be attached to the base via an elastic body and may be enabled to be lifted and lowered with respect to the base within a range of an amount of elastic deformation of the elastic body.

According to this configuration, variations in height of the stacked body can be absorbed by the elastic body, and thus the one or more heat-dissipation tools can be reliably brought into contact with the stacked body.

In addition, in this case, a height of a bottom surface of the heat-dissipation tool in a no-load state may be lower than a height of a bottom surface of the press-attaching tool.

According to this configuration, by lowering the heat-dissipation tool capable of absorbing the variations in height of the stacked body, both the heat-dissipation tools and the press-attaching tool can reliably come into contact with the stacked body.

In addition, the heat-dissipating body may be cooled by a refrigerant.

According to this configuration, other stacked bodies positioned around the target stacked body can be more effectively cooled.

In addition, the final press-attachment head may have one of the press-attaching tool and eight of the heat-dissipation tools, and the press-attaching tool and the heat-dissipation tools may be arranged in three rows and three columns with the press-attaching tool as a center.

According to this configuration, it is possible to cool all of the stacked bodies around the stacked body being finally press-attached.

A mounting system of the present invention is a mounting system for stacking and mounting two or more semiconductor chips at a plurality of locations on a substrate, the mounting system including: a temporary press-attaching device for forming, at a plurality of locations on the substrate, temporarily stacked bodies in which two or more semiconductor chips are stacked in a temporarily press-attached state; and a final press-attaching device for forming chip stacked bodies by sequentially finally press-attaching the temporarily stacked bodies formed at the plurality of locations by the temporary press-attaching device. The final press-attaching device has a press-attaching tool for heating and pressing an upper surface of a target temporarily stacked body to thereby finally press-attach the two or more semiconductor chips configuring the temporarily stacked body altogether, and one or more heat-dissipation tools having a heat-dissipating body which, by coming into contact with an upper surface of another stacked body positioned around the target temporarily stacked body, dissipates heat from the another stacked body. [Effect]

Effect

According to the present invention, when final press-attachment is performed, other stacked bodies positioned around a target stacked body can be pinpointed and cooled, and thus it is possible to prevent an NCF from hardening in the stacked body before the final press-attachment, while preventing a decrease in temperature of the stacked body being finally press-attached.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention are described with reference to the drawings.FIG. 1is a diagram of a schematic configuration of a mounting apparatus100according to an embodiment of the present invention. The mounting apparatus100is a device that mounts a semiconductor chip10on a substrate30. The mounting apparatus100has a configuration which is particularly preferred in a case of stacking and mounting a plurality of semiconductor chips10. Moreover, in the following description, bodies formed by stacking a plurality of semiconductor chips10are referred to as “stacked bodies ST”, further, the “stacked bodies ST” are distinguished as follows. A body of the plurality of semiconductor chips10in a temporarily press-attached state is referred to as a “temporarily stacked body STt”, and a body of the plurality of semiconductor chips10in a finally press-attached state is referred to as a “chip stacked body STc”.

The mounting apparatus100includes a chip supply unit102, a chip transport unit104, a bonding unit106, and a control unit128that controls drive of the units. The chip supply unit102is a part that picks up the semiconductor chip10from a chip supply source and supplies the semiconductor chip to the chip transport unit104. The chip supply unit102has a projecting-upward portion110, a die picker114, and a transport head116.

In the chip supply unit102, a plurality of semiconductor chips10are placed on a dicing tape TE. In this case, the semiconductor chip10is placed in a face-up state in which a bump18faces upward. The projecting-upward portion110pushes up only one semiconductor chip10of the plurality of semiconductor chips10while the semiconductor chips are in the face-up state. The die picker114suction-holds and receives, by a lower end of the die picker, the semiconductor chip10pushed up by the projecting-upward portion110. The die picker114that has received the semiconductor chip10rotates by 180 degrees at this position so that the bump18of the semiconductor chip10faces downward, that is, so that the semiconductor chip10comes into a face-down state. In this state, the transport head116receives the semiconductor chip10from the die picker114.

The transport head116is movable in up-down and horizontal directions and can suction-hold the semiconductor chip10by a lower end of the transport head. When the die picker114rotates by 180 degrees and the semiconductor chip10comes into the face-down state, the transport head116suction-holds the semiconductor chip10by the lower end of the transport head. Then, the transport head116moves in the horizontal and up-down directions to move to the chip transport unit104.

The chip transport unit104has a rotary table118that rotates around a vertical rotation axis Ra. The transport head116places the semiconductor chip10at a predetermined position of the rotary table118. The rotary table118, at which the semiconductor chip10is placed, rotates around the rotation axis Ra, and thereby the semiconductor chip10is transported to the bonding unit106that is positioned at an opposite side of the chip supply unit102.

The bonding unit106includes a first mounting head124(temporary press-attachment head) that temporarily press-attaches the semiconductor chip10or a stage120which supports the substrate30, a second mounting head126(final press-attachment head) that finally press-attaches the semiconductor chip10, and the like. The stage120is movable in the horizontal direction and adjust a relative positional relationship between the substrate30placed thereon and the mounting heads124and126. In addition, a heater is internally arranged in the stage120, and the heater heats the semiconductor chip10from below.

The first mounting head124can hold the semiconductor chip10by a lower end of the first mounting head and can rotate around a vertical rotary axis Rb and can be lifted and lowered. In addition, the first mounting head124has a built-in heater (not shown) and is heated to a set first temperature T1. The first mounting head124functions as a temporary press-attachment head that temporarily press-attaches the semiconductor chip10on the substrate or another semiconductor chip10.

The second mounting head126can be lifted and lowered. In addition, the second mounting head126has a built-in heater (not shown) and is heated to a second temperature T2higher than the first temperature T1. The second mounting head126functions as a final press-attachment head that heats and presses the temporarily press-attached semiconductor chips10at the second temperature T2, thereby finally attaching the semiconductor chips10. Here, the second mounting head126of the embodiment has one press-attaching tool130that performs heating and pressing by coming into contact with the target semiconductor chip10(more accurately, the temporarily stacked body STt) and a plurality of heat-dissipation tools132arranged around the press-attaching tool130. A specific configuration of the press-attaching tool130or the heat-dissipation tool132is described later in detail.

A camera (not shown) is arranged in the vicinity of the first mounting head124and the second mounting head126. An alignment mark which is a positioning reference is attached to each of the substrate30and the semiconductor chip10. The camera images the substrate30and the semiconductor chip10in a manner that the alignment mark appears. Based on image data obtained by the imaging, the control unit128grasps a relative positional relationship between the substrate30and the semiconductor chip10and adjusts a rotation angle of the first mounting head124around the axis Rb and a horizontal position of the stage120as necessary. The control unit128controls drive of the units and includes, for example, a CPU that performs various types of arithmetic processes and a storage section that stores various items of data or programs.

Next, a semiconductor device which is manufactured by the mounting apparatus100is described. In the embodiment, a semiconductor wafer is used as the substrate30, and a plurality of semiconductor chips10are stacked and mounted on the semiconductor wafer (substrate30). Hence, a mounting process of the embodiment is a “chip-on-wafer process” of stacking and mounting the semiconductor chip10on a circuit forming surface of the semiconductor wafer.FIG. 2is a schematic image view of the substrate30(semiconductor wafer) used in the embodiment. The substrate30which is a semiconductor wafer is mainly made of silicon and has a heat transfer coefficient higher than that of a general circuit substrate made of resin or glass. As shown inFIG. 2, a plurality of arrangement regions34arranged in a grid shape are set on the substrate30. The plurality of semiconductor chips10are stacked and mounted in the arrangement regions34. The arrangement regions34are arranged at predetermined arrangement pitches P. A value of the arrangement pitch P is appropriately set depending on a size or the like of the semiconductor chip10as a mounting target. In addition, in the embodiment, the arrangement region34has a substantially square shape; however, the arrangement region34may have another shape such as a substantially rectangular shape.

Next, a configuration of the semiconductor chip10is described.FIG. 3is a diagram showing a schematic configuration of the semiconductor chip10which is mounted. Electrode terminals14and16are formed on upper and lower surfaces of the semiconductor chip10. In addition, the bumps18are formed to be continuous to the electrode terminals14on one surface of the semiconductor chip10. The bump18is made of conductive metal and melts at a predetermined melting temperature Tm.

In addition, a non-conductive film (hereinafter, referred to as the “NCF”)20is bonded to the one surface of the semiconductor chip10so as to cover the bump18. The NCF20functions as an adhesive for adhering the semiconductor chip10to the substrate30or another semiconductor chip10and is made of non-conductive thermosetting resin such as polyimide resin, epoxy resin, acrylic resin, phenoxy resin, polyester sulfone resin or the like. The NCF20has a thickness larger than an average height of the bumps18, and the bumps18are substantially completely covered by the NCF20. The NCF20is a solid film at room temperature; however, when the temperature is higher than a predetermined softening start temperature Ts, the NCF reversibly softens gradually to exert fluidity and, when the temperature is higher than a predetermined hardening start temperature Tt, the NCF starts to irreversibly harden.

Here, the softening start temperature Ts is lower than the melting temperature Tm of the bump18and the hardening start temperature Tt. The first temperature T1for temporary press-attachment is higher than the softening start temperature Ts and is lower than the melting temperature Tm and the hardening start temperature Tt. In addition, the second temperature T2for final press-attachment is higher than the melting temperature Tm and the hardening start temperature Tt. That is, Ts<T1<(Tm, Tt)<T2is satisfied.

When the semiconductor chip10is temporarily press-attached to the substrate30or a semiconductor chip10at a lower side (hereinafter, referred to as a “lower chip or the like”), the first mounting head124is heated to the first temperature T1and then pushes and presses the semiconductor chip10to the lower chip or the like. In this case, the NCF20of the semiconductor chip10is heated to the softening start temperature Ts or higher by the heat transmitted from the first mounting head124, thereby softening and having fluidity. Consequently, the NCF20can enter a gap between the semiconductor chip10and the lower chip or the like, and the gap can be reliably filled with the NCF.

When the semiconductor chip10is finally press-attached, the second mounting head126is heated to the second temperature T2and, then, presses the semiconductor chip10. At this time, the bumps18and the NCF20of the semiconductor chip10are heated to a temperature equal to or higher than the hardening start temperature Tt and the melting temperature Tm by the heat transmitted from the second mounting head126. Consequently, the bumps18can melt and adhere to the lower chip or the like that faces the bumps18. In addition, the NCF20hardens due to the heating in a state that the gap between the semiconductor chip10and the lower chip or the like is filled with the NCF, and thus the semiconductor chip10and the lower layer are strongly fixed.

FIG. 4is a diagram showing a configuration of a semiconductor device in which a plurality of semiconductor chips10are stacked and mounted on the electrode32on the substrate30. In the semiconductor device, chip stacked bodies STc formed by stacking and mounting semiconductor chips10having a target stacking number are arranged in a plurality of arrangement regions34(regions A to C, in the example shown in the drawing), respectively. In the embodiment, the target stacking number is “4”, and the chip stacked body STc containing four semiconductor chips10is mounted in one arrangement region34.

The semiconductor device described above is manufactured in the following procedure. First, the first mounting head124is used to form a plurality of temporarily stacked bodies STt formed by stacking the semiconductor chips10while temporarily press-attaching the semiconductor chips10. In the example ofFIG. 4, when the temporarily stacked body STt is formed at the region A, subsequently, the temporarily stacked body STt is formed at the region B, and then the temporarily stacked body STt is further formed at the region C.

When the temporarily stacked bodies STt are formed at all of the arrangement regions34, then, the temporarily stacked bodies STt are finally press-attached sequentially. That is, the second mounting head126heated to the second temperature T2is used to heat and press an upper surface of a target temporarily stacked body STt and to finally press-attach the plurality of (in the example, four) semiconductor chips10configuring the target temporarily stacked body STt altogether. Consequently, the temporarily stacked body STt changes into the chip stacked bodies STc in which the semiconductor chips10configuring the temporarily stacked body are finally press-attached. When one temporarily stacked body STt is finally press-attached (changes into the chip stacked body STc), subsequently, the next temporarily stacked body STt is finally press-attached. Then, all of the temporarily stacked bodies STt are finally press-attached, and a manufacturing process is ended.

In a case of a method that performs, in the above manner, the final press-attachment after the plurality of temporarily stacked bodies STt are formed, the number of times of switching between the mounting heads or the like can be reduced, and thus processing time of the complete mounting processing can be reduced, compared with a method that performs final press-attachment after one temporarily stacked body STt is formed. On the other hand, in the case of the method that performs the final press-attachment after the plurality of temporarily stacked bodies STt are formed, a problem arises in that the NCF20irreversibly hardens in the temporarily stacked body STt other than the temporarily stacked body STt which is a target of the final press-attachment. This is described with reference toFIG. 5.FIG. 5is an image view showing a state of the final press-attachment in the related art.

As described above, when one temporarily stacked body STt is finally press-attached to change into the chip stacked body STc, the upper surface of the temporarily stacked body STt is heated and pressed by the mounting head for final press-attachment. In a conventional mounting apparatus, as shown inFIG. 5, a mounting head for final press-attachment has only a press-attaching tool130that heats and presses the temporarily stacked body STt and does not have the heat-dissipation tool132that dissipates heat from adjacent temporarily stacked bodies STt.

A case is considered in which the conventional mounting apparatus described above is used to finally press-attach the temporarily stacked body STt at the middle region B after the temporarily stacked bodies STt are formed at the regions A, B, and C. In this case, the press-attaching tool130is used to heat and press the temporarily stacked body STt at the region B. At this time, the second temperature T2which is the temperature of the press-attaching tool130is set to be higher than the hardening start temperature Tt of the NCF20and the melting temperature Tm of the bumps18of the lowest semiconductor chip10. Then, the semiconductor chip is heated at the second temperature T2, and thereby the bumps18of the target temporarily stacked body STt (temporarily stacked body STt at the region B inFIG. 5) melt, and the NCF20starts to irreversibly harden.

Here, as shown by thick arrows inFIG. 5, the heat applied from the press-attaching tool130is transmitted not only to the temporarily stacked body STt at the region B which is a target of final press-attachment, but also to the temporarily stacked body STt at the adjacent region A or C via the substrate30. In particular, when the substrate30has high heat conductivity like a semiconductor wafer, heat is transmitted to an adjacent temporarily stacked body STt with high efficiency. As a result, not only the target of final press-attachment but also the adjacent temporarily stacked bodies STt are heated to the hardening start temperature Tt of the NCF20or higher, and there is a concern that the NCF20of the temporarily stacked bodies STt at the regions A and C irreversibly harden before the final press-attachment. When the NCF20hardens before the final press-attachment, defective mounting of the semiconductor chip10is brought about. In addition, even when the temporarily stacked bodies STt are not heated to the hardening start temperature Tt or higher, a start of reaction of a hardening agent contained in the NCF20needs to be sufficiently considered. In this case, it is difficult to obtain original characteristics of the NCF20.

Therefore, in the embodiment, in order to prevent the hardening of the NCF20of the temporarily stacked body STt other than the temporarily stacked body STt being the target of final press-attachment, the second mounting head126is equipped with not only the press-attaching tool130but also the heat-dissipation tool132. This is described with reference toFIGS. 6 and 7.FIG. 6is a diagram showing a schematic configuration of the second mounting head126. In addition,FIG. 7is a diagram of the second mounting head126when viewed from a bottom side.

The second mounting head126has a base140and the press-attaching tool130and the heat-dissipation tools132attached to the base140. The base140is attached to a lifting/lowering mechanism not shown and is lifted and lowered in response to an instruction from the control unit128.

The press-attaching tool130is pressed against the upper surface of the temporarily stacked body STt being the target of final press-attachment, thereby pressing and heating the temporarily stacked body STt. The press-attaching tool130has a heater131arranged internally and is heated to the set second temperature T2.

An upper end of the press-attaching tool130is fixed to the base140, and a position of the press-attaching tool130with respect to the base140does not change.

The heat-dissipation tools132are arranged in eight directions around the press-attaching tool130. InFIG. 7, outline quadrangles represent the heat-dissipation tools132, and a hatched quadrangle represents the press-attaching tool130. As shown inFIG. 7, the second mounting head126has one press-attaching tool130and eight heat-dissipation tools132, and the press-attaching tool130and the heat-dissipation tools132are arranged in three rows and three columns with the press-attaching tool130as a center. An arrangement pitch Q of the press-attaching tool130and the heat-dissipation tools132is the same as the arrangement pitch P of the stacked bodies ST. Hence, when the press-attaching tool130comes into contact with one stacked body ST, the heat-dissipation tools132adjacent to the press-attaching tool130come into contact with other stacked bodies ST adjacent to the one stacked body ST.

The heat-dissipation tool132dissipates heat from other stacked bodies ST apart from the stacked body ST being the target of final press-attachment to cool the other stacked bodies. A heat-dissipating body134is arranged at a lower end of the heat-dissipation tool132. The heat-dissipating body134is a block-shaped member containing a material having a high heat transfer rate, such as copper, aluminium or the like. The heat-dissipating body134functions as a heat sink that comes into contact with upper surfaces of other stacked bodies ST around the temporarily stacked body STt being the target of final press-attachment and dissipates heat from the other stacked bodies ST. The heat transmitted from the other stacked bodies ST to the heat-dissipating body134is released to external air, a columnar body136to be described below, or the like.

Moreover, inFIG. 6, the heat-dissipating body134has a simple rectangular parallelepiped shape; however, the shape of the heat-dissipating body134may be appropriately modified. For example, in order to improve dissipation efficiency of the heat-dissipating body134, a plurality of fins, ribs, or protrusions may be arranged on an upper surface or a lateral surface of the heat-dissipating body134. In addition, in order to improve cooling performance of the heat-dissipating body134, the heat-dissipating body134may be cooled by using a refrigerant. That is, a refrigerant channel through which the inside and the outside of the heat-dissipating body134communicate with each other may be arranged to make a liquid refrigerant or gaseous refrigerant circulate in the refrigerant channel. In addition, as another example, heat of the heat-dissipating body134may be transferred to the outside of the heat-dissipating body by using a heat pipe. In addition, as still another example, the heat-dissipating body134may be cooled by using a Peltier element. In both examples, it is desirable that a bottom surface of the heat-dissipating body134, that is, a contact surface with the stacked body ST, is a flat surface so as to come into contact with the entire upper surface of the stacked body ST. Moreover, in order to prevent temperature decrease of the press-attaching tool130, it is desirable that an optional insulation member (not shown) is arranged between the press-attaching tool130and the heat-dissipation tools132.

In addition, the heat-dissipating body134is attached to the base140via an elastic body138and can be lifted and lowered with respect to the base140within a range of an amount of elastic deformation of the elastic body138. Various methods for attaching via the elastic body138are considered and, in the embodiment, as shown inFIG. 6, the columnar body136is inserted through a through-hole which penetrates the base140, and flanges139uand139dhaving a diameter larger than that of the through-hole are arranged at both sides of the columnar body136with the base140interposed therebetween. Then, a compression spring serving as the elastic body138is disposed between a bottom surface of the base140and the lower flange139d. The compression spring biases the lower flange139d, eventually the heat-dissipating body134, downward in a no-load state. On the other hand, when the heat-dissipating body134receives an upward force as a reaction force when the heat-dissipating body134pushes the stacked body ST, the compression spring is compressively deformed, and thereby the heat-dissipating body134is displaced in a direction in which the heat-dissipating body approaches the base140.

By attaching the heat-dissipation tool132to the base140via the elastic body138in this way, a difference in height for each stacked body ST can be absorbed, and all of the eight heat-dissipating bodies134can come into close contact with the upper surface of the corresponding stacked body ST. Moreover, in order for the heat-dissipating body134to reliably come into close contact with the corresponding stacked body ST, it is desirable that a height of the bottom surface of the heat-dissipating body134in the no-load state (state in which the elastic body is not deformed) is lower than the height of the bottom surface of the press-attaching tool130(be separated from the base140). In addition, it is desirable that a spring constant of the elastic body138is adjusted so that the elastic body138can be elastically deformed under a first load F1which is a load for the temporary press-attachment.

Next, the final press-attachment performed by using the second mounting head126is described with reference toFIG. 8.FIG. 8is an image view showing a state of performing the final press-attachment by using the second mounting head126of the embodiment. In the example ofFIG. 8, the temporarily stacked bodies STt are formed at the regions A to C and then the temporarily stacked body STt at the middle region B is finally press-attached. In this case, the press-attaching tool130is lowered and is pushed to the upper surface of the temporarily stacked body STt at the region B, which is the target of final press-attachment. Consequently, the temporarily stacked body STt at the region B is heated and pressed. It is needless to say that, when the base140is lowered, in order to lower the press-attaching tool130, the heat-dissipation tools132attached to the base140are also lowered in connection with the base140and the press-attaching tool130. Consequently, the heat-dissipation tools132come into contact with the upper surfaces of the temporarily stacked bodies STt at the regions A and C, which are adjacent to the temporarily stacked body STt being the target of final press-attachment.

Here, slight variations in height occur in the plurality of temporarily stacked bodies STt. For example, in the example ofFIG. 8, the temporarily stacked body STt at the region A has a height higher than that of the other temporarily stacked bodies STt. In this case, when the position of the heat-dissipation tool132with respect to the base140does not change, that is, when the elastic body138is not arranged, a problem arises in that, after the heat-dissipation tool132comes into contact with the temporarily stacked body STt at the region A, the heat-dissipation tools132cannot come into contact with the temporarily stacked bodies STt corresponding to the press-attaching tool130and the heat-dissipation tools132at the regions B and C. In the embodiment, the heat-dissipation tools132are attached to the base140via the elastic body138and can be displaced with respect to the base140. Hence, even after one heat-dissipation tool132comes into contact with the temporarily stacked body STt, the elastic body138of the one heat-dissipation tool132is deformed when the base140is continuously lowered, and the other heat-dissipation tools132and the press-attaching tool130are allowed to be further lowered. As a result, the heat-dissipation tool132and the plurality of press-attaching tools130can reliably come into contact with the corresponding stacked bodies ST. Moreover, at this time, when the elastic body138has a high spring constant, a very large force is applied to the temporarily stacked body STt at the region A when the elastic body138is deformed. Therefore, the spring constant of the elastic body138is adjusted so that a load required for such deformation is equal to or smaller than the load F1for the temporary press-attachment.

In this manner, in the embodiment, when the temporarily stacked body STt at the region B is finally press-attached, the heat-dissipation tools132are brought into contact with the temporarily stacked bodies STt at the regions A and C adjacent to the region B. In this case, as shown by thick arrows inFIG. 8, the heat of the press-attaching tool130is transmitted to the temporarily stacked bodies STt at the regions A and C via the temporarily stacked body STt at the region B and the substrate30. However, in the embodiment, the heat-dissipating body134having good thermal conductivity comes into contact with the upper surfaces of the temporarily stacked bodies STt at the regions A and C. Heat transmitted to the temporarily stacked bodies STt at the regions A and C is released to the heat-dissipating body134and then released to the outside. As a result, an increase in temperature of the temporarily stacked bodies STt at the regions A and C, which are not the target of final press-attachment, is effectively inhibited. Consequently, the NCFs20of the temporarily stacked bodies STt at the regions A and C are prevented from hardening before the final press-attachment, and defective mounting of the semiconductor chip10can be effectively prevented.

Here, as a cooling method of the stacked body ST, a method of directly applying a fluid such as cold air or a liquid to the stacked body ST is also considered, in addition to the method of causing a solid (heat-dissipating body134) having high thermal conductivity to come into contact with the stacked body as in the embodiment. However, it is difficult to limit an application range of the fluid, and there is a concern that the temporarily stacked body STt being the target of final press-attachment which actually needs to be prevented from cooling is likely to be cooled. When the temporarily stacked body STt being the target of final press-attachment is cooled, there is a concern that the NCF20insufficiently hardens or the bumps18insufficiently melt, and defective mounting is brought about after all. On the other hand, according to a technology of the embodiment in which the heat-dissipating body134is brought into contact with the stacked body so that heat is dissipated, the stacked body ST which needs to be cooled can be reliably cooled, and a decrease in temperature of the temporarily stacked body STt which needs to be heated is inhibited. As a result, according to the embodiment, it is possible to effectively prevent defective mounting caused by insufficient temperature or defective mounting caused by hardening of the NCF20before the final press-attachment.

Next, experimental results related with cooling effects achieved by the heat-dissipating body134are described.FIG. 9is a diagram showing an experimental condition. In addition,FIGS. 10 and 11are graphs showing experimental results. In the experiment, the press-attaching tool130is used to heat and press one semiconductor chip10. Then, at this time, a temperature TC1of a bottom surface of the semiconductor chip10and a temperature TC2of a bottom surface of the lowest layer and a temperature TC3of a bottom surface of the top layer of the stacked body ST arranged adjacent to the one semiconductor chip10are measured. Although condition1and condition2are common in that a resin substrate is used as the substrate30, the conditions are different from each other in that the heat-dissipation tool132is not used in condition1, and the heat-dissipation tools132are used to cool the stacked bodies ST in condition2. Although condition3and condition4are common in that a glass substrate is used as the substrate30, the conditions are different from each other in that the heat-dissipation tool132is not used in condition3, and the heat-dissipation tools132are used to cool the stacked bodies ST in condition4.

InFIG. 10, an outline bar represents measured temperatures TC1to TC3in condition1, and a black-painted bar represents measured temperatures TC1to TC3in condition2. In addition, inFIG. 11, an outline bar represents measured temperatures TC1to TC3in condition3, and a black-painted bar represents measured temperatures TC1to TC3in condition4. As clearly understood fromFIGS. 10 and 11, there is no big difference between the temperatures TC1of the semiconductor chip10which is heated by the press-attaching tool130in conditions1and3(outline bars) and conditions2and4(black-painted bars), and there is little side effect on the final press-attachment even when the heat-dissipation tools132are arranged. On the other hand, in conditions2and4(black-painted bars) in which the heat-dissipation tools132are used, the temperatures TC2and TC3of the adjacent stacked bodies ST are lower, compared with conditions1and3(outline bars) in which the heat-dissipation tool132is not used. In other words, it is known that, according to the embodiment in which the heat-dissipation tools132are used, an increase in temperature of the stacked bodies ST adjacent to the stacked body ST being the target of final press-attachment can be inhibited, and hardening or the like of the NCF20can be effectively prevented even before the adjacent stacked bodies ST are finally press-attached. On the other hand, even when the heat-dissipation tools132are used, a decrease in temperature of the semiconductor chip10being the target of final press-attachment is prevented, and thus the semiconductor chip10can be finally press-attached reliably.

Moreover, the configuration described above is an example. As long as the mounting head (second mounting head126) for final press-attachment includes the press-attaching tool130that heats and presses the temporarily stacked body STt and the heat-dissipation tools132that dissipate heat from other stacked bodies ST adjacent to the temporarily stacked body STt, a configuration other than the configuration described above may be appropriately modified. For example, in the embodiment, the press-attaching tool130and the heat-dissipation tools132are configured to be integrally lifted and lowered; however, the press-attaching tool130and the heat-dissipation tools132may be configured to be lifted and lowered independently from each other.

In addition, in the embodiment, the heat-dissipation tools132are arranged in eight directions around the press-attaching tool130; however, the heat-dissipation tools do not absolutely need to be arranged in the eight directions. For example, as shown by an arrow A′ inFIG. 12, a case is considered in which the final press-attachment of the temporarily stacked bodies STt is performed by alternately repeating a step of sequentially proceeding in a right direction and a step of sequentially proceeding in a left direction for each row. In this case, the stacked body ST is not present at a lower side in the drawing than the temporarily stacked body STt being finally press-attached, or even when the stacked body ST is present, the final press-attachment of the stacked body ST is completed. In this case, the heat-dissipation tool132does not need to be arranged at a lower side than the press-attaching tool130in the drawing. Hence, in this case, as shown inFIG. 13, the heat-dissipation tools132may be arranged at totally five locations of both right and left sides of the press-attaching tool130and three locations at an upper side in the drawing.

In addition, arrangement intervals between the press-attaching tool130and the heat-dissipation tools132may be capable of being appropriately changed depending on the arrangement pitches P of the arrangement regions. In addition, in the embodiment, the mounting head (first mounting head124) for the temporary press-attachment and the mounting head (second mounting head126) for the final press-attachment are separately arranged; however, the temporary press-attachment and the final press-attachment may also be performed by one mounting head. That is, the first mounting head124may not be arranged, and the temporary press-attachment and the final press-attachment may be performed by the second mounting head126. Here, when the temporary press-attachment is performed, because the heat-dissipation tool132does not absolutely need to be arranged, the heat-dissipation tool132may be detached from the second mounting head126during the temporary press-attachment.

In addition, in the description above, the mounting head (first mounting head124) for the temporary press-attachment and the mounting head (second mounting head126) for the final press-attachment are arranged in a single device; however, the mounting heads may be arranged in separate devices, respectively. That is, the technology disclosed in the present application may also be applied to a mounting system including a temporary press-attaching device equipped with the mounting head for temporary press-attachment and a final press-attaching device equipped with the mounting head for final press-attachment.