JP7103822B2 - Mounting device and mounting method - Google Patents

Description

The present invention relates to a mounting method and a mounting device for mounting an electronic component having bumps on a substrate having electrodes. In particular, the present invention relates to a mounting device and a mounting method for flip-chip mounting a semiconductor chip having bumps on a substrate having electrodes.

In the development of electronic devices, there are various demands for the electronic components mounted therein, and development is being promoted in an early cycle to meet these demands. As part of this, in the method of mounting electronic components such as semiconductor chips on a substrate, flip-chip mounting is becoming widespread in order to meet the demands for shortening the transmission distance and downsizing. Flip-chip mounting is a method of joining bumps of electronic components to electrodes of a substrate, but a method of using solder bumps as bumps is often adopted.

In recent years, even in flip-chip mounting, bumps have been miniaturized and bump intervals have been narrowed against the background of demands for improved mounting density. On the other hand, in the construction method using solder bumps, the solder is provided at the tip of the copper pillar. However, due to the decrease in solder due to the reduction in the diameter of the copper pillars, the proportion of mechanically brittle intermetallic compounds generated at the interface between the solder and other metals (electrodes on the substrate, copper pillars) increases, resulting in bonding. It adversely affects the reliability of the department.

For this reason, as the mounting density is improved, a construction method that does not use solder is required, and flip-chip mounting using ultrasonic waves or the like is drawing attention. In flip-chip mounting using ultrasonic waves, a method of joining gold bumps to gold-plated electrodes has been put into practical use, but it has not been sufficiently popularized due to the use of expensive gold and the like. However, if inexpensive copper can be used for bumps and electrodes, it is expected to spread rapidly. Therefore, efforts toward the practical application of flip-chip mounting using copper bumps and copper electrodes are also in progress (Patent Document 1, Patent Documents). 2).

Japanese Unexamined Patent Publication No. 2016-201501 Japanese Patent Application No. 2017-153747

When copper, which has higher rigidity than gold or the like, is used as a bump, when the tip portion is uneven as in the bump PB shown in FIG. 12 (a), or when the electrode E is pressed and joined, FIG. 12 ( As in b), the tips are only partially joined. For this reason, it is not preferable because not only the joining strength but also the conductivity is lowered as compared with the case where the entire tip portion is joined.

Further, when the height of the bump PB varies between the bumps as shown in FIG. 13A, the rigidity of the bump is high. Therefore, in the bump PB having a low bump height, only a very small part of the tip portion is joined to the electrode E. Without doing so, the joining reliability is reduced.

The present invention has been made in view of the above problems, and when an electronic component such as a semiconductor chip that uses a metal having a higher rigidity than gold as a bump is flip-chip mounted on a substrate without using solder, an electron is used. It provides a mounting device and a mounting method with high joint reliability between a bump of a component and an electrode of a substrate.

In order to solve the above problems, the invention according to claim 1 is
It is a mounting device that joins the bumps of electronic components and the electrodes of the substrate to mount the electronic components on the substrate.
A stage that attracts and holds the substrate from the surface opposite to the surface on which the electrodes are present,
A bonding head having a function of sucking and holding the electronic component from the surface opposite to the surface on which the bump exists and applying a drive and a load toward the substrate.
A paste transfer unit that transfers the metal particle paste to the bump,
A stage cover that accommodates the stage and has an opening through which the bonding head can pass at a position facing the bonding head, an air supply means for supplying gas into the stage cover, the stage, and the bonding. A control unit for controlling the operation of the head , the paste transfer unit, and the air supply means is provided.
In the process of lowering the bonding head to bring the electronic component closer to the substrate,
The control unit controls the air supply means to control the amount of gas supplied into the stage cover according to the height position of the bonding head with respect to the height of the opening, and the bonding head controls the amount of gas supplied into the stage cover. This is a mounting device in which the control unit controls the stage so that the stage reciprocates in the in-plane direction of the substrate when the electronic component is pressed against the substrate.

The invention according to claim 2 is the mounting apparatus according to claim 1.
The bonding head is a mounting device having a heater having a built-in electric heating member .

The invention according to claim 3 is the mounting apparatus according to claim 1 or 2.
This is a mounting device provided so that the paste transfer unit moves in the in-plane direction of the substrate in conjunction with the stage.

The invention according to claim 4 is the mounting apparatus according to claim 1 or 2.
It is a mounting device further provided with a transport means for transporting the electronic component to the bonding head, and the paste transfer unit is provided in the transport means.

The invention according to claim 5
A mounting method for mounting an electronic component on a substrate by joining a bump of an electronic component and an electrode of the substrate by using the mounting device according to any one of claims 1 to 4.
A paste transfer step of transferring the metal particle paste to the bumps of the electronic component, a positioning step of aligning the electronic component and the substrate so that the bumps are arranged to face the electrodes, and a bump and the electrode. It is provided with an approaching step of bringing the electronic component closer to the substrate until the electronic component comes into contact with the substrate, and a pressurizing step of pressurizing the electronic component toward the substrate after the bump and the substrate come into contact with each other.
This is a mounting method in which a reciprocating motion of the substrate in the in-plane direction is applied to at least one of the substrate and the electronic component in the pressurizing step.

The invention according to claim 6 is the mounting method according to claim 5.
In the approaching step, an inert gas or a reducing gas is supplied around the substrate and the electronic component.
In the pressurizing step, the mounting method is such that the oxygen concentration in the space including the bump and the electrode is 1% or less.

According to the mounting apparatus and mounting method of the present invention, the bumps of electronic components and the electrodes of the substrate can be joined by flip-chip mounting with high conductivity and high reliability.

It is a figure which shows the appearance of the mounting apparatus which concerns on embodiment of this invention. It is a figure explaining the component which concerns on embodiment of this invention. It is a figure explaining the stage and the bonding head of the mounting apparatus which concerns on embodiment of this invention. It is a block diagram which shows the control structure of the mounting apparatus which concerns on embodiment of this invention. It is a figure explaining the state when the mounting apparatus which concerns on embodiment of this invention performs a paste transfer process. (A) It is a figure which shows the state which arranged the paste transfer part just under the semiconductor chip in the paste transfer process which concerns on embodiment of this invention (b) in the same transfer process, the semiconductor chip is lowered and the pillar bump is made into a metal particle. It is a figure which shows the state of being immersed in the paste (c) is a figure which shows the state which the metal particle paste was transferred to the tip of the pillar bump of the semiconductor chip in the same transfer process (d) The semiconductor chip which concerns on embodiment of this invention. It is a figure which shows the state which is aligned with the substrate in the alignment process. (E) It is a figure which shows the state which the pillar bump of a semiconductor chip and the electrode of a substrate are aligned in the alignment step. (F) It is a figure which shows the process of bringing a semiconductor chip close to a substrate in the bonding process which concerns on embodiment of this invention (g) is a figure which shows the state which the pillar bump of a semiconductor chip is bonded to the electrode of a substrate in the same bonding process. It is a figure which shows the state after the pressurization to a semiconductor chip in a certain (h) joining process is completed. (A) It is a figure which shows the way where the pillar bump of a semiconductor chip and an electrode of a substrate are approaching in the joining process which concerns on embodiment of this invention (b) is a figure which shows the state which the pillar bump and the electrode are joined in the same joining process. .. (A) In the joining step according to the embodiment of the present invention, it is a diagram showing the process of approaching a substrate under the condition that the semiconductor chips have pillar bumps having different heights. (B) The pillar bumps are attached to the electrodes under the same conditions. It is a figure which shows the joined state. (A) It is a figure explaining the transport means which transports a semiconductor chip, (b) is the figure explaining the example which provided the paste transfer part in the transport means in another embodiment of this invention. (A) It is a figure which shows the state before the bonding head holds a semiconductor chip in the mounting apparatus which concerns on another Embodiment of this invention (b) after the bonding head holds a semiconductor chip in the same mounting apparatus. It is a figure which shows the state (c) is the figure which shows the paste transfer process using the paste transfer part provided in the transport means in the same mounting apparatus. (A) It is a figure which shows the state before joining of the joining process which metal-joins a pillar bump which is made of a metal material with high rigidity and has an uneven tip part and an electrode, (b) is a figure which shows the state after joining of the same joining process. Is. (A) In the joining step of metal-joining a pillar bump made of a highly rigid metal material and having an uneven tip and an electrode, the pillar bump having a height variation is in the process of approaching a substrate (b). It is a figure which shows the state which the pillar bump is bonded to an electrode in a process.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the appearance of the mounting apparatus 1 according to the embodiment of the present invention, and FIG. 2 shows the components hidden in the appearance. Further, FIG. 3 is a cross-sectional view of a main part of the mounting device 1, and FIG. 4 is a block diagram showing a control configuration of the mounting device 1.

The mounting device 1 mounts a semiconductor chip C, which is an electronic component, on a substrate W, and includes a base 2, a support frame 3, a stage 4, a stage cover 40, a nozzle 41, a pressure unit 5, a bonding head 6, and an image. It includes a recognition means 7, a vacuum pump 8 (FIG. 3), a paste transfer unit 9 and a control unit 10 (FIG. 4). In FIGS. 1 and 2, the left-right direction is the X direction, the depth direction is the Y direction, the vertical direction is the Z direction, and the direction of rotation with the Z direction as the central axis is the θ direction.

As shown in FIG. 6D, the semiconductor chip C has a pillar bump PB, and the substrate W has an electrode E. When the semiconductor chip C is mounted on the substrate W, the semiconductor chip C is mechanically fixed on the substrate W while electrically joining the pillar bump PB and the electrode E.

In the present embodiment, copper is assumed as the material of the pillar bump PB and the electrode E, but the material is not limited to this. Other metal materials may be used as long as the conductivity and mechanical properties are suitable for the intended use, and the pillar bump PB and the electrode E may be different materials. Further, a thin film of nickel or gold may be formed on the surface of the pillar bump PB and / or the electrode E by plating or the like.

The base 2 is a main structure constituting the mounting device 1. The base 2 is configured to have sufficient rigidity. The base 2 supports the support frame 3 and the stage 4.

The support frame 3 supports the pressurizing unit 5. The support frame 3 is configured to extend in the Z direction from the vicinity of the stage 4 of the base 2.

The stage 4 moves the substrate W while holding it. The stage 4 is composed of a Y-direction drive unit 4a, an X-direction drive unit 4b, and a suction table 4c. The stage 4 is attached to the base 2 so that the suction table 4c can be moved in the X direction by the X-direction drive unit 4b and the suction table 4c (the X-direction drive unit 4b and) can be moved in the Y direction by the Y-direction drive unit 4a. Has been done. Further, FIG. 3 shows a cross-sectional view of the main part of the mounting device 1. The suction table 4c has a substrate suction hole 4H for sucking the substrate W, and an in-stage flow provided in the suction table 4c. It leads to the vacuum pump 8 via the road 4E. Here, the inside of the substrate suction hole 4H can be depressurized by the operation of the vacuum pump 8 and the valve 4V provided in the flow path leading to the vacuum pump 8, and the substrate W can be sucked and held on the suction table 4c.

With the above configuration, the stage 4 can move the substrate W adsorbed by the adsorption table 4c on the base 2 in the X direction and the Y direction which are the in-plane directions of the substrate W.

The stage cover 40 is a cover provided on the base 2 and accommodating the stage 4, and has an opening 40H on the upper surface facing the bonding head 6. The substrate W may be taken in and out by providing an opening / closing portion on the side surface of the stage cover 40, or the stage cover 40 may be raised to take in and out the substrate W.

The nozzle 41 is provided to supply gas to the inside covered with the stage cover 40, and constitutes the air supply means of the present invention together with a valve (not shown). As the valve, a valve capable of controlling the flow rate or pressure may be used. The role of the gas supplied from the nozzle 41 is to reduce the oxygen concentration inside the stage cover 40, and an inert gas or a reducing gas is used. As the inert gas, nitrogen or a rare gas can be used, but since the rare gas is expensive, it is desirable to use nitrogen. As the reducing gas, an inert gas containing a small amount of a reducing gas such as hydrogen is preferable.

The pressurizing unit 5 moves the bonding head 6. The pressurizing unit 5 is configured to generate a driving force in the axial direction of the ball screw by rotating the ball screw with a servomotor (not shown). The pressurizing unit 5 is configured to generate a driving force (pressurizing force) in the Z direction in which the axial direction of the ball screw is perpendicular to the substrate W. The pressurizing unit 5 is configured so that the load Pz in the Z direction can be arbitrarily set by controlling the output of the servomotor. From the viewpoint of positional deviation during bonding, it is desirable that the bonding head 6 is configured to be movable only in the Z direction.

In the present embodiment, the pressurizing unit 5 is composed of a servomotor and a ball screw, but the present invention is not limited to this, and the pressurizing unit 5 may be composed of a pneumatic actuator, a hydraulic actuator, or a voice coil motor. Further, the pressurizing unit 5 may have a function of rotating the bonding head 6 in the θ direction.

The bonding head 6 transmits the driving force of the pressurizing unit 5 to the semiconductor chip C and heats the semiconductor chip. As shown in FIG. 3, the bonding head 6 is composed of an attachment tool 61, a heater 62, a heat insulating block 63, and a head body 64.

The attachment tool 61 is provided with an electronic component suction hole 6H, and the electronic component suction hole 6H is connected to the vacuum pump 8 via an in-head flow path 6E formed in the bonding head 6. Here, the inside of the electronic component suction hole 6H can be depressurized by the operation of the vacuum pump 8 and the valve 6V provided in the flow path leading to the vacuum pump 8, and the semiconductor chip C can be sucked and held by the attachment tool 61. Further, the heater 62 may have a built-in electric heating member such as a ceramic heater, and may have a built-in temperature sensor for controlling the heater temperature.

The bonding head 6 is attached to a ball screw and a nut (not shown) constituting the pressurizing unit 5. That is, the bonding head 6 (attachment tool 61) is arranged so as to face the stage 4 (suction table 4c) in parallel. That is, the bonding head 6 is moved in the Z direction by the pressurizing unit 5, so that the semiconductor chip C can be brought closer to the substrate W. The opening 40H on the upper surface of the stage cover 40 is passed through the bonding head 6 so that the stage cover 40 does not become an obstacle in the process of moving the bonding head 6 in the Z direction to bring the semiconductor chip C closer to the substrate W. It has a shape. At that time, the gap between the bonding head 6 and the opening 40H (edge) is 0.1 mm to 5 mm so as to sufficiently reduce the oxygen concentration at the time of bonding and to prevent the pressure inside the stage cover 40 from rising too much. It is desirable to do. Further, the gap of the opening 40H may be changed according to the attachment tool 61. In this case, it is preferable because it can correspond to various sizes.

In the mounting apparatus 1, the image recognition means 7 acquires the position information of the semiconductor chip C and the substrate W from the image. The image recognition means 7 image-recognizes the alignment mark on the upper surface of the substrate W held on the stage 4 and the alignment mark of the semiconductor chip C held on the bonding head 6, and recognizes the alignment mark of the substrate W and the semiconductor chip C. It is configured to acquire position information (in the XY plane).

The paste transfer unit 9 stores the metal particle paste NP having a predetermined thickness, and has a saucer shape in which all the pillar bumps PB of the semiconductor chip C are simultaneously immersed. The metal particle paste NP having a predetermined thickness is supplied in a predetermined amount by a paste supply means (not shown), and a stencil printing mechanism, a dispenser, or the like is used as a specific paste supply means.

Here, as the metal particle paste NP, it is preferable that the metal particles dispersed in the resin binder contain so-called metal nanoparticles having a particle size of less than 1 μm. This is because the low temperature of sintering can be achieved by containing fine metal particles. Further, in the present embodiment, it is premised that the pillar bump PB of the semiconductor chip C and the electrode E of the substrate W are copper, and copper particles are suitable as the metal particles, but the substrate W is not limited thereto. Other metal particles such as silver particles, tin particles, and indium particles may be used depending on the application as a semiconductor element after mounting and the conditions such as the heating temperature at the time of sintering. The binder resin is generally an epoxy resin, but may be a polyimide resin, an acrylic resin, or the like, and is an ink-like resin in which metal nanoparticles are dispersed in a solvent without using a binder resin. May be good.

As shown in FIG. 2, the paste transfer unit 9 of the mounting apparatus 1 of the present embodiment is arranged so as to be connected to the suction table 4c, and like the suction table 4c, the suction table is driven by the Y-direction drive unit 4. The 4c is configured to be movable in the Y direction and in the X direction by the X direction drive unit 4b. Therefore, it is also possible to arrange the paste transfer portion 9 directly below the bonding head 6 as shown in FIG.

As shown in FIG. 4, the control unit 10 is connected to the stage 4, the nozzle 41, the pressurizing unit 5, the bonding head 6, and the image recognition means 7. Further, the vacuum pump 8 may be independent of the control unit 10, but may be connected to the control unit 10. The control unit 10 may actually have a configuration in which a CPU, ROM, HDD, etc. are connected by a bus, or may have a configuration including a one-chip LSI. The control unit 10 stores various programs and data for acquiring and controlling signals from the connection destination.

The control unit 10 is connected to the stage 4 and individually controls the Y-direction drive unit 4a and the X-direction drive unit 4b. Further, the control unit 10 controls the presence / absence of suction of the substrate W by the suction table 4c by controlling the valve 4V. Therefore, the control unit 10 can arbitrarily change the position of the substrate W in the XY plane by controlling the Y-direction suction unit 4a, the Y-direction suction unit 4b, and the valve 4V.

The control unit 10 is connected to the stage 4 and individually controls the Y-direction drive unit 4a and the X-direction drive unit 4b. Further, the control unit 10 controls the presence / absence of suction of the substrate W by the suction table 4c by controlling the valve 4V. Therefore, the control unit 10 can arbitrarily change the position of the substrate W in the XY plane by controlling the Y-direction suction unit 4a, the Y-direction suction unit 4b, and the valve 4V.

The control unit 10 is connected to the pressurizing unit 5 and can control the height and load Pz of the pressurizing unit 5 in the Z direction. Further, when the pressurizing unit 5 has a function of rotating the bonding head 6 in the θ direction, the control unit 5 may be configured to control the rotation angle of the bonding head in the θ direction.

The control unit 10 is connected to the bonding head 6 and can control the heater 62 to a predetermined temperature. Further, the control unit 10 controls the valve 6V to control the presence or absence of adsorption of the semiconductor chip C by the attachment tool 61.

The control unit 10 is connected to the image recognition means 7, can control the position of the image recognition means 7, and can acquire the position information of the substrate W and the semiconductor chip C from the image information.

When connected to the vacuum pump 8, the control unit 10 controls the vacuum pump 8 to operate before the start of the mounting operation. Therefore, the presence or absence of adsorption of the substrate W and the semiconductor chip C is controlled by opening and closing the valves 4V and 6V.

Hereinafter, the process of mounting the semiconductor chip C on the substrate W using the mounting devices 1 described with reference to FIGS. 1 to 4 will be described with reference to FIGS. 6 and 7.

First, FIGS. 6 (a) to 6 (c) are diagrams for explaining the paste transfer process. FIG. 6A shows a state in which the attachment tool 61 of the bonding head 6 sucks and holds the semiconductor chip C conveyed by the conveying means (not shown), and the paste transfer unit 9 is arranged directly under the semiconductor chip C. There is. Here, the paste transfer unit 9 is arranged directly below the semiconductor chip C as shown in FIG. 7 by the control unit 10 controlling the Y-direction drive unit 4a and the X-direction drive unit 4b of the stage 4. .. When adjusting the position of the paste transfer unit 9 directly under the semiconductor chip C, the image recognition means 7 may be used.

After arranging the paste transfer unit 9 directly under the semiconductor chip C as shown in FIG. 6A, the control unit 10 controls the pressurizing unit 5 to lower the bonding head 6 by a predetermined length. By this operation, as shown in FIG. 6B, the pillar bump PB of the semiconductor chip C is immersed in the metal particle paste NP stored in the paste transfer unit 9. The thickness of the metal particle paste NP in the paste transfer unit 9 is controlled by, for example, a laser displacement meter or the like.

After the immersion is performed, when the control unit 10 controls the pressurizing unit 5 to raise the bonding head 6, the metal particle paste NP is transferred to the individual pillar bumps PB of the semiconductor chip C as shown in FIG. 6 (c). It will be in a state of being. The metal particle paste NP is supplied to the paste transfer unit 9 at a predetermined timing, and the thickness is kept constant by using a squeegee.

6 (d) and 6 (e) are diagrams for explaining the alignment process. In the alignment step, first, the control unit 10 moves the substrate W in the horizontal direction by controlling the Y-direction drive unit 4a and the X-direction drive unit 4b of the stage 4, and the mounted portion of the substrate W is transferred to the semiconductor chip C. After arranging it in the immediate vicinity, the alignment is performed so that the electrode E is arranged directly under the pillar bump PB. When the image recognition means 7 is used for positioning, it is not preferable that it takes time for image recognition between FIGS. 6 (d) and 6 (e) when the atmosphere is in contact with the pillar bump PB. Therefore, before the paste transfer step, the image recognition means 7 is used to confirm the position so that the electrode E is arranged directly under the pillar bump PB, and the positioning based on the position information stored at that time is performed after the paste transfer step. You may go.

When the alignment step is completed, the positions of the electrodes E and the bumps B are aligned in the direction perpendicular to the facing surfaces of the substrate W and the semiconductor chip C (FIG. 6 (e)). From this state, the bonding head 6 is lowered to bring the semiconductor chip C closer to the substrate W as shown in FIGS. 6 (e) to 7 (f).

In this approaching step, the control unit 10 controls to supply the inert gas GP from the nozzle 41. Therefore, in the approaching step, the internal atmosphere covered with the stage cover 40 is replaced with the inert gas, and the oxygen concentration decreases.

By the way, even during the same approach, if the supply of the inert gas GP is started at the timing when the attachment 61 of the bonding head 6 is separated from the opening 40H of the stage cover 40, the supplied inert gas GP can be used. Most of it is discharged from the opening 40H, which is wasted. On the other hand, if the supply of the inert gas GP is started just before the pillar bump PB of the semiconductor chip C and the electrode E of the substrate W come into contact with each other, the joining with the inert gas starts at an insufficient stage, which is not preferable. .. Therefore, it is preferable to start supplying the inert gas GP at the timing when the attachment tool 61 of the bonding head 6 passes through the opening 40H of the stage cover 40.

If it is desired to sufficiently reduce the oxygen concentration inside the stage cover 40, the inert gas GP is supplied from the timing when the attachment 61 of the bonding head 6 is separated from the opening 40H of the stage cover 40. May be good. In this case, in the process in which the bonding head 6 approaches the opening 40H, the area of the opening 40H becomes a substantial opening area, but in the stage where the bonding head 6 passes through the opening 40H, the area of the opening 40H. The difference between the area of the bonding head 6 (the portion having the same height as the opening 40H) and the area of the bonding head 6 is the substantial opening area. Therefore, the amount of the inert gas GP supplied by the nozzle 41 may be increased at the stage when the bonding head 6 approaches the opening 40H, and may be reduced after the bonding head 6 starts passing through the opening 40H.

After the pillar bump PB comes into contact with the electrode E, the pillar bump PB and the electrode E are joined to mount the semiconductor chip C on the substrate W. At that time, since it is necessary to pressurize the semiconductor chip C toward the substrate W, this step is called a pressurization step (FIG. 7 (g)).

The supply of the inert gas GP from the nozzle 41, which was started in the approaching step, is continued in the pressurizing step, and the space including the pillar bump PB and the electrode E is maintained at a low oxygen concentration. Here, the specific oxygen concentration at the start of the pressurizing step is preferably 3% or less, and more preferably 1% or less. The oxygen concentration can be measured by installing the sensor in the opening 40H of the stage cover 40.

As described above, in the mounting device 1, the inside of the stage cover 41 covering the stage 4 is a semi-enclosed space, and the air is easily replaced with the inert gas GP. Therefore, the oxygen concentration in the space including the bump B and the electrode E is 1%. It is easy to do the following: Further, as compared with the case where the entire mounting apparatus is put in a closed system, in the present embodiment, since the volume for replacing the gas is limited, it takes a short time such as the process in which the bonding head 6 descends. It is also possible to reduce the oxygen concentration to 1% or less. That is, it is possible to suppress an increase in tact time due to replacement of gas. The waiting time may be set when the bonding head 6 is lowered so that the mounting can be performed at a predetermined oxygen concentration or less.

In the pressurizing step, the semiconductor chip C is heated via the attachment tool 61 by heating the heater 62. In this heating, the pillar bump B of the semiconductor chip C, the metal particle paste NP, and the electrode E of the substrate W in contact with the pillar bump B are set to 100 ° C. or higher, so that the bump B and the metal material forming the electrode E are mutually formed. It becomes easy to diffuse, and the possibility of joining the bump B and the electrode E increases. Therefore, the heating temperature of the heater 62 is set to 100 ° C. or higher. However, if the bump B is heated to a temperature exceeding 200 ° C., the bonded metal is oxidized, which is unsuitable, and for example, a plastic film having low heat resistance cannot be used as the substrate W. Therefore, the temperature of the heater 62 is 200. It is preferable that the control unit 10 controls the heater 62 so as not to exceed the ° C. Here, the heating temperature of the heater 62 is the temperature between the semiconductor chip C and the substrate W. For example, in the pressurizing step, which can be measured by sandwiching a thermocouple (SF50) between the semiconductor chips C, the bonding head 6 is lowered while the heater 62 is heated, and the semiconductor chip C is attached to the substrate W. The pressure is applied toward the semiconductor chip C with a load Pz, but in the present invention, the semiconductor chip C and the substrate W are further reciprocated in a direction along the facing surface.

By the way, in the pressurizing step, the conventional ultrasonic bonding is also included only by performing a reciprocating motion between the semiconductor chip C and the substrate W along the opposing surface. There are differences such as.

In the case of the mounting device 1, by moving the substrate W in the in-plane direction by the stage 4, reciprocating motion in the direction along the facing surface between the semiconductor chip C and the substrate W is realized, so that the bonding head 6 is used. There are no restrictions on the shape like an ultrasonic bonding head, and a significant load increase can be achieved compared to ultrasonic bonding. Further, if both the suction table 4c and the attachment tool 61 have a flat surface shape, even if the substrate W is moved in the in-plane direction by the stage 4, it is always the same regardless of the position of the semiconductor chip C. It is possible to apply pressure.

The number of reciprocating motions required in the present invention is preferably 2 or more and 20 or less. Further, in the present invention, it is preferable that the time for performing the reciprocating motion is 1 second or more and 10 seconds or less. That is, the oxide film can be removed by two or more reciprocating motions in 1 second or more, and sufficient bonding strength can be obtained by 20 or less reciprocating motions in 10 seconds or less.

FIG. 8 is an enlarged view of the state leading to this pressurization process. FIG. 8A shows a state in which the metal particle paste NP is attached to the recent portion of the pillar bump PB having an uneven shape, and FIG. 8B shows a state in which the semiconductor chip C is pressed toward the substrate W. be. In the state of FIG. 8B, since the oxide film is removed by the reciprocating motion as described above in an atmosphere of low oxygen concentration, in addition to the metal bonding between the convex portion at the tip of the pillar bump PB and the electrode E, Pressure and frictional force are also applied to the metal particles constituting the metal particle paste NP, and the oxide film is partially removed. Therefore, the metal particles taken into the recess at the tip of the pillar bump PB expand the contact area between the pillar bump PB and the electrode E, and a bond having excellent conductivity is realized. Further, the metal particle paste NP is sintered by the heat generated by the heater 62 of the bonding head 6 and the heat generated by the wear, and the bonding strength between the pillar bump PB and the electrode E can be improved and the mounting temperature can be lowered.

Further, since the metal particle paste PB taken into the recess at the tip of the pillar bump PB is involved in the bonding, even if the pillar bump PB has a height variation, the conductivity and the bonding strength of the pillar bump PB with the electrode E vary. Can also be reduced. That is, even if the height of the pillar bump PB varies as shown in FIG. 9 (a), the metal particle paste PB interposed between the tip of the pillar bump PB and the electrode E as shown in FIG. 9 (b) Since it plays a role of improving the conductivity and the bonding strength, the variation in the conductivity and the bonding strength between the pillar bumps PB is reduced.

In addition, in order to sufficiently sinter the metal particle paste PB, a separate sintering step may be added. That is, if the pressurizing step shown in FIG. 7 (g) is completed and the sintering of the metal nanoparticle paste PB is insufficient with the bonding head raised as shown in FIG. 7 (h), the semiconductor chip C By heat-treating the substrate W on which the above-mentioned material is mounted in a reflow furnace or the like, the conductivity and the bonding strength can be improved.

By the way, when supplying the semiconductor chip C to the attachment tool 61 of the bonding head 6, something like the chip slider 17 shown in FIG. 10A is generally used. The chip slider 17 slides along the transport rail while holding the semiconductor chip C in the transport means 11. If the semiconductor chip is placed directly under the attachment tool 61, the bonding head 6 is subsequently lowered. The attachment tool 61 sucks and holds the semiconductor chip C.

Therefore, as another embodiment of the present invention using this mechanism, a paste transfer unit 19 (similar to the paste transfer unit 9 of the mounting device 1) is attached to the transfer unit slider 18 that performs the same operation as the chip slider 17. An example of mounting is shown in FIG. 10 (b), and the operation thereof is shown in FIG.

FIG. 11A shows a state in which the chip slider 17 holding the semiconductor chip C moves along the transport rail 16 and the semiconductor chip C is arranged directly under the attachment tool 61. FIG. 11B shows the attachment tool. 61 is a state after adsorbing and holding the semiconductor chip C and then rising. After the state shown in FIG. 11B, the transfer unit slider 18 moved along the transfer rail 16 and the paste transfer unit 19 was placed directly under the attachment tool 61 (semiconductor chip C held by the attachment tool C). Is shown in FIG. 11 (c). After that, as the bonding head 6 descends and rises, the metal particle paste NP is copied to the pillar bump PB of the semiconductor chip C in the same manner as shown in FIGS. 6 (a) to 6 (c).

Since it is necessary to avoid the metal particle paste NP from adhering to the semiconductor chip C itself in the paste transfer step, it is assumed that the columnar pillar bump PB is used as the bump, but the metal particles are formed only in the vicinity of the bump tip. The present invention is not limited to the pillar bump PB as long as the paste NP can be transferred, and the present invention is effective even if bumps having other shapes are used.

1 Mounting device 2 Base 3 Frame 4 Stage 4a Y direction drive unit 4b X direction drive unit 4c Suction table 4E Exhaust flow path 4H Board suction hole 5 Pressurization unit 6 Bonding head 6H Electronic component suction hole 7 Image recognition device 8 Vacuum pump 9, 19 Paste transfer unit 10 Control unit 11, 12 Transport means 16 Transport rail 17 Chip slider 18 Supply slider 40 Stage cover 40H Opening 41 Nozzle 61 Attachment tool 62 Heater C Semiconductor chip E board NP Metal particle paste PB Pillar bump W board

Claims (6)

It is a mounting device that joins the bumps of electronic components and the electrodes of the substrate to mount the electronic components on the substrate.
A stage that attracts and holds the substrate from the surface opposite to the surface on which the electrodes are present,
A bonding head having a function of sucking and holding the electronic component from the surface opposite to the surface on which the bump exists and applying a drive and a load toward the substrate.
A paste transfer unit that transfers the metal particle paste to the bump,
A stage cover that accommodates the stage and has an opening through which the bonding head can pass at a position facing the bonding head.
An air supply means for supplying gas into the stage cover and
A control unit for controlling the operation of the stage, the bonding head, the paste transfer unit, and the air supply means is provided.
In the process of lowering the bonding head to bring the electronic component closer to the substrate,
The control unit controls the air supply means to control the amount of gas supplied into the stage cover according to the height position of the bonding head with respect to the height of the opening.
A mounting device in which the control unit controls the stage so that the bonding head reciprocates the stage in the in-plane direction of the substrate when the electronic component is pressed against the substrate. The mounting device according to claim 1.
A mounting device in which the bonding head has a heater having a built-in electric heating member. The mounting device according to claim 1 or 2.
A mounting device provided so that the paste transfer unit moves in the in-plane direction of the substrate in conjunction with the stage. The mounting device according to claim 1 or 2.
Further provided with a transport means for transporting the electronic component to the bonding head,
A mounting device in which the paste transfer unit is provided in the transport means. A mounting method for mounting an electronic component on a substrate by joining a bump of an electronic component and an electrode of the substrate by using the mounting device according to any one of claims 1 to 4.
A paste transfer step of transferring the metal particle paste to the bumps of the electronic component,
An alignment step of aligning the electronic component and the substrate so that the bumps are arranged to face the electrodes.
An approach step of bringing the electronic component closer to the substrate until the bump and the electrode come into contact with each other.
A pressurizing step of pressurizing the electronic component toward the substrate after the bump and the substrate come into contact with each other is provided.
A mounting method in which a reciprocating motion of the substrate in the in-plane direction is applied to at least one of the substrate and the electronic component in the pressurizing step. The mounting method according to claim 5.
In the approaching step, an inert gas or a reducing gas is supplied around the substrate and the electronic component.
In the pressurizing step, a mounting method in which the oxygen concentration in the space containing the bump and the electrode is 1% or less.

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