Bonding device

Abstract

To join an electronic component and a substrate efficiently by the use of laser light while preventing oxidation of a solder bump.SOLUTION: Laser light irradiation means 6 is provided above an opening part 5a of a cover member 5 such that laser light L emitted by the laser light irradiation means 6 passes through the opening part 5a, and at least a part of a shutter member 12a of shutter means 12 provided to the cover member 5 is composed of a transmission member capable of transmitting the laser light L. The laser light irradiation means 6 emits the laser light L while the opening part 5a of the cover member 5 is closed by the shutter means 12 and a bonding head 7 retracts from the opening part 5a, so that a semiconductor wafer 2 (substrate) held at a bonding stage 4 is irradiated with the laser light L through the transmission member of the shutter member 12a.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a bonding apparatus, and more particularly to a bonding apparatus that heats and melts solder bumps with a laser beam to bond electronic components to a substrate when bonding the electronic components to the substrate.

Background Art

[0002] Conventionally, as a bonding apparatus for bonding electronic components to a substrate, there is known one including a bonding stage on which a substrate having solder bumps formed on its upper surface is placed, a laser beam irradiation means for irradiating a laser beam, a bonding head for holding an electronic component, and a moving means for relatively moving the bonding stage and the bonding head (Patent Document 1). According to the above bonding apparatus, the bonding head is moved by the moving means, and with the electronic component held by the bonding head in contact with the substrate, a laser beam is irradiated from the laser beam irradiation means, so that the electronic component is heated by the laser beam transmitted through the tool base, and further the solder bump is melted to bond the electronic component to the substrate. Also, as a bonding apparatus having another configuration, there is known one provided with a cover member disposed above the bonding stage and having an opening through which the bonding head can pass, and a stage-side gas supply means for supplying an atmospheric gas between the cover member and the bonding stage (Patent Document 2). According to the above bonding apparatus, by filling the atmosphere gas between the cover member and the bonding stage, oxidation of the solder bump when bonding the electronic component to the substrate is prevented.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the bonding apparatus disclosed in Patent Document 2 above, after bonding a substrate and an electronic component, in order to bond a new electronic component to the substrate, it is necessary to move the bonding head and detach the bonding head from the opening of the cover member. At this time, outside air may enter between the cover member and the bonding stage through the opening, and there is a risk that the solder bumps on the substrate may oxidize. In addition, there is a problem that bonding between the electronic component and the substrate cannot be performed while the bonding head is detached from the opening and is at the receiving position or alignment position of the electronic component, and efficient operation has been demanded. In view of such problems, the present invention provides a bonding apparatus capable of preventing oxidation of solder bumps and performing bonding efficiently.

MEANS FOR SOLVING THE PROBLEMS

[0005] That is, the bonding apparatus according to the invention of claim 1 includes a bonding stage for holding a substrate having solder bumps formed on its upper surface, a laser light irradiation means for irradiating laser light, a bonding head for transmitting the laser light and holding an electronic component, a moving means for relatively moving the bonding stage and the bonding head, a cover member disposed above the bonding stage and having an opening through which the bonding head can pass, a shutter means for opening and closing the opening, a stage-side gas supply means for supplying an atmospheric gas between the cover member and the bonding stage, and a control means for controlling these, and is a bonding apparatus. The laser light irradiation means is provided above the opening of the cover member such that the laser light irradiated by the laser light irradiation means passes through the opening, and at least a part of the shutter member of the shutter means is constituted by a transmissive member through which the laser light can pass. The control means irradiates laser light by the laser light irradiation means in a state where the opening of the cover member is closed by the shutter means and the bonding head is retracted from the opening by the moving means, so that the laser light is irradiated onto the substrate held on the bonding stage through the transmissive member of the shutter member.

Advantages of the Invention

[0006] According to the invention of claim 1, since the opening of the cover member can be opened and closed by the shutter means, the opening is closed while the bonding head is detached to prevent the inflow of air from the opening between the cover member and the bonding stage, and the oxidation of the solder bumps provided on the substrate can be prevented. In addition, since the laser light irradiation means is provided above the opening and a part of the shutter means is constituted by a transmissive member, it is possible to perform processing on the substrate held on the bonding stage by the laser light transmitted through the transmissive member while the bonding head is detached from the opening, so that efficient bonding can be performed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, referring to the illustrated embodiment, FIG. 1 shows a bonding apparatus 3 for bonding an electronic component 1 to a semiconductor wafer 2 as a substrate. In the following description, the illustrated left - right direction is defined as the X - direction, the illustrated depth direction is defined as the Y - direction, and the illustrated up - down direction is defined as the Z - direction for explanation. A plurality of electrodes 1a (see FIG. 4) are formed on the back surface of the electronic component 1, and solder bumps B are formed on each electrode 1a. The semiconductor wafer 2 has a disk shape (see FIG. 2), and as shown in FIG. 4, electrodes 2a for bonding a plurality of electronic components 1 are formed on the upper surface of the semiconductor wafer 2, and solder bumps B are also formed on each electrode 2a. Here, an oxide film composed of SnO, CuO, etc. is formed on the surface of the solder bump B of the semiconductor wafer 2 in the process of forming the solder bump B. Since such an oxide film causes poor bonding between the electrode 1a and the electrode 2a, it is necessary to remove it when bonding the electronic component 1 and the semiconductor wafer 2. Conventionally, flux was applied to the surface of the solder bump B on which the oxide film was formed, and when bonding the electronic component 1, the solder bump B was heated and melted to reduce the oxide film with the flux. However, this method requires removing the flux after bonding the electronic component 1. In recent years, the density of the electrodes 2a of the electronic component 1 is high and the miniaturization of the solder bump B has advanced, so it has become difficult to remove the flux after bonding. Therefore, in the bonding apparatus 3 of the present embodiment, it is possible to perform a flux - less bonding for bonding the electronic component 1 and the semiconductor wafer 2 without using flux. In the drawings for explaining the present embodiment, for the purpose of explanation, the ratio of the sizes of the electronic component 1 and the semiconductor wafer 2 is made different from the actual ratio, and the electronic component 1 is shown larger.

[0009] The bonding apparatus 3 includes a bonding stage 4 that supports the semiconductor wafer 2, a cover member 5 provided above the bonding stage 4, a laser light irradiation means 6 provided above the cover member 5 for irradiating a laser beam L, two bonding heads 7 that hold the electronic component 1, a moving means 8 that relatively moves the bonding stage 4 and the bonding heads 7, and an electronic component supply stage 9 that supplies the electronic component 1, and these are controlled by a control means C composed of a computer or the like. Further, the bonding apparatus 3 of the present embodiment includes an atmosphere gas replacement means 10 that replaces the periphery of the semiconductor wafer 2 with an atmosphere gas such as N2 gas when bonding the electronic component 1 and the semiconductor wafer 2.

[0010] The bonding stage 4 includes a semiconductor wafer support portion 4a that supports the semiconductor wafer 2 and an outer peripheral guide 4b that surrounds the semiconductor wafer support portion 4a, and these are movable in the horizontal direction by an X-Y stage 11 that constitutes the moving means 8. The upper surface of the semiconductor wafer support portion 4a is processed to be flat and has a circular shape with a diameter larger than that of the semiconductor wafer 2 in a plan view shown in FIG. 2. Further, the semiconductor wafer support portion 4a can adsorb and hold the semiconductor wafer 2 on its upper surface by an adsorption means (not shown). The outer peripheral guide 4b is provided so as to surround the outside of the semiconductor wafer support portion 4a, and its upper surface is formed at the same height as the semiconductor wafer support portion 4a. Also, the size of the outer peripheral guide 4b is set to a width such that no disturbance of the atmosphere gas occurs around the semiconductor wafer 2 when the atmosphere gas described later is circulated.

[0011] The above X-Y stage 11 is composed of a stage base 11a provided below the semiconductor wafer support portion 4a, a table 11b that holds the stage base 11a, and an X-direction driving means 11c and a Y-direction driving means 11d provided on the lower surface of the table 11b. Since the X-direction driving means 11c and the Y-direction driving means 11d are conventionally well-known, detailed descriptions thereof are omitted, but they are constituted by a pair of rails and sliders provided orthogonally.

[0012] The above cover member 5 is a plate-like member fixed by fixing means (not shown) above the bonding stage 4, and an opening 5a is formed above the semiconductor wafer 2 held by the bonding stage 4, and the opening 5a is configured to be opened and closed by shutter means 12. The above cover member 5 has an area capable of sufficiently covering the movement range of the semiconductor wafer 2 that moves by the above X-Y stage 11, and is configured to partition the atmosphere above and below the cover member 5. The above opening 5a has a size through which the bonding head 7 can pass. When the bonding head 7 is inserted into the opening 5a from above, a gap is formed between the opening 5a and the bonding head 7.

[0013] As shown in FIG. 3, the above shutter means 12 is composed of a plate-like shutter member 12a that covers the opening 5a, a shutter opening / closing means 12b that moves the shutter member 12a, and a shutter housing member 12c that houses the outer peripheral edge of the moved shutter member 12a. The above shutter member 12a is formed to be of a size that covers the opening 5a. In the present embodiment, the entire shutter member 12a is constituted by a transmissive member (such as quartz or glass) through which the laser beam L can pass. Note that the transmissive member may be provided only in the irradiation range of the laser beam L by the laser beam irradiation means 6. The shutter opening / closing means 12b horizontally moves the shutter member 12a along the upper surface of the cover member 5, and is configured to switch between a closed state in which the opening 5a is closed and an open state in which the opening 5a is opened. The shutter opening / closing means 12b can be constituted by an air cylinder, an electric cylinder, or the like. The shutter housing member 12c is provided so as to surround the opening 5a, and a concave portion is formed toward the opening 5a. When the shutter member 12a is in the closed state as shown in FIG. 3, the outer peripheral edge of the shutter member 12a fits into the concave portion of the shutter housing member 12c, and the opening 5a is closed while maintaining airtightness.

[0014] The laser light irradiation means 6 is provided separately from the bonding head 7 and is fixed above the semiconductor wafer support portion 4a of the bonding stage 4. The laser light irradiation means 6 includes a laser oscillator (not shown), and in the present embodiment, it is a semiconductor laser (laser diode, LD), and the output and wavelength of the irradiated laser light L can be changed. For example, laser light L having a wavelength of 900 nm to 1080 nm, which has a high absorption rate by many lead-free solders, can be irradiated. When the laser light irradiation means 6 irradiates the laser light L downward, it is configured to irradiate the semiconductor wafer 2 held on the bonding stage 4 through the opening 5a of the cover member 5.

[0015] As shown in FIG. 1, two sets of the bonding head 7 and the electronic component supply stage 9 are provided respectively. The moving means 8 includes an X-direction rail 13 provided in the X direction above the bonding stage 4, an X-direction moving means 14 for moving each bonding head 7 along the X-direction rail 13, a lifting means 15 for lifting and lowering the bonding head 7 in the Z direction, and a rotation mechanism (not shown) for rotating the housing 21 together with the electronic component 1. At one end and the other end of the X-direction rail 13, bonding heads 7 are respectively positioned, and below these bonding heads 7, electronic component supply stages 9 are respectively provided. The X-direction moving means 14 reciprocates one bonding head 7 between the opening 5a of the cover member 5 and one electronic component supply stage 9, and reciprocates the other bonding head 7 between the opening 5a and the other electronic component supply stage 9. Also, the elevating means 15 is configured to lower the bonding head 7 from a state where the bonding head 7 is positioned above the cover member 5 and insert it into the opening 5a. Further, the rotation mechanism rotates the held electronic component 1 corresponding to the position of the electrode 2a of the semiconductor wafer 2.

[0016] As shown in FIG. 4, the bonding head 7 includes a housing 21 having a substantially square tube shape, and a tool base 23 provided at the lower part of the housing 21 and holding the bonding tool 22 and the electronic component 1. The housing 21 is movably provided by the moving means 8, and has a substantially square tube shape in a plan view shown in FIG. 5 that penetrates from the upper part to the lower part. The bonding tool 22 is a ceramic plate-like member having an area larger than that of the electronic component 1, and is used in a state of being adsorbed and held by the bonding tool 22. Although detailed description is omitted, it is replaceable during the operation of the bonding apparatus 3. Also, the bonding tool is impermeable to the laser beam L, and when the bonding tool 22 is irradiated with the laser beam L, it absorbs the laser beam L and is heated.

[0017] The tool base 23 includes an upper plate 23a provided above for transmitting the laser beam L and a lower plate 23b provided below, and a holder 23c for holding the outer peripheral portions of these plates 23a and 23b, and is connected to a tool negative pressure supply means 24 for adsorbing the bonding tool 22 and an electronic component negative pressure supply means 25 for adsorbing the electronic component 1. The upper plate 23a and the lower plate 23b are made of a transparent material such as quartz or glass that transmits the laser beam L from the laser beam irradiation means 6, and have a substantially square shape with an area larger than that of the bonding tool 22. Also, a spacer 23d provided endlessly along the outer peripheral edge is sandwiched between the upper plate 23a and the lower plate 23b, so that a space S is formed between the two plates 23a and 23b. As shown in FIG. 5, four tool suction ports h1 are formed in the lower plate 23b at positions outside the electronic component 1 to be adsorbed and held, and one electronic component suction port h2 is formed substantially at the center of the electronic component 1. The four tool suction ports h1 are formed within the range where the spacer 23d and the lower plate 23b overlap, and tool negative pressure passages 24a communicating with the respective tool suction ports h1 are formed inside the upper plate 23a and the spacer 23d and are connected to the tool negative pressure supply means 24. According to the above configuration, when the tool negative pressure supply means 24 supplies negative pressure to the tool negative pressure passage 24a, the bonding tool 22 can be adsorbed and held on the lower surface of the lower plate 23b by the four tool suction ports h1.

[0018] On the other hand, the electronic component suction port h2 provided in the lower plate 23b communicates with the space S formed between the two plates 23a and 23b, and the electronic component negative pressure supply means 25 is connected to the space S via the electronic component negative pressure passages 25a provided in the upper plate 23a and the spacer 23d. On one hand, a through hole is formed at approximately the center of the bonding tool 22 at the same position as the suction port h2 for electronic components of the lower plate 23b, which constitutes the suction port h2 for electronic components. According to the above configuration, when the negative pressure supply means 25 for electronic components supplies negative pressure to the negative pressure passage 25a for electronic components, the electronic component 1 is adsorbed and held on the lower surface of the bonding tool 22 through the suction port h2 for electronic components and the suction port h2 for electronic components formed in the bonding tool 22 via the space S. Note that the bonding apparatus 3 of the present embodiment can also hold the electronic component 1 without using the bonding tool 22. In this case, only the negative pressure supply means 25 for electronic components is operated to adsorb and hold the electronic component 1 at the suction port h2 for electronic components of the lower plate 23b.

[0019] In addition, a cylindrical hood 26 is provided around the housing 21 in the bonding head 7 of the present embodiment. The hood 26 is formed to surround the opening 5a of the cover member 5 in a plan view. An endless seal member 26a is provided at the upper end of the hood 26 so as to be in close contact with the outer surface of the housing 21 and slidable along the outer surface of the housing 21. On one hand, a flange portion 21a is formed at the lower end of the housing 21 so as to protrude outward, and the flange portion 21a can contact the seal member 26a of the hood 26 from below. With such a configuration, as shown in FIG. 6, when the bonding head 7 is located above the cover member 5, the hood 26 moves downward due to its own weight, and the seal member 26a and the flange portion 21a come into contact with each other. On one hand, as shown in FIG. 4, when the bonding head 7 is lowered with the lower end of the hood 26 in contact with the upper surface of the shutter means 12 provided on the upper portion of the cover member 5, the hood 26 is prevented from descending by the shutter means 12, and only the bonding head 7 relatively descends and is inserted into the opening 5a. At this time, since the hood 26 surrounds the opening 5a, the inside of the hood 26 communicates with the space below the cover member 5 through the opening 5a. On the other hand, since a seal member 26a that closely contacts the outer surface of the bonding head 7 is provided on the upper portion of the hood 26, it is partitioned from the space above the cover member 5.

[0020] The atmosphere gas replacement means 10 includes a stage-side gas supply means 31 (see FIG. 1) that supplies an atmosphere gas between the cover member 5 and the bonding stage 4, and a head-side gas supply means 32 (see FIG. 4) that supplies an atmosphere gas around the electronic component 1 held by the bonding head 7. The stage-side gas supply means 31 includes an inert gas supply source 33 that supplies an inert gas as the atmosphere gas, a nozzle 34 that supplies the inert gas between the bonding stage 4 and the cover member 5, and a rectifying guide 35 that guides the inert gas jetted from the nozzle 34 to the semiconductor wafer support portion 4a. The inert gas supply source 33 is configured to supply N2 gas or argon gas as the inert gas. When bonding the electronic component 1 to the semiconductor wafer 2, by supplying an inert gas between the bonding stage 4 and the cover member 5, an oxide film can be prevented from being formed on the solder bump B by the inert gas.

[0021] The nozzle 34 is fixed to the table 11b of the X-Y stage 11 and is provided so as to be movable integrally with the semiconductor wafer support portion 4a and the outer peripheral guide 4b. Further, the nozzle 34 is provided only to the left side in the drawing with respect to the semiconductor wafer support portion 4a. The injection port 34a of the nozzle 34 is formed at the same height as the upper surfaces of the semiconductor wafer support portion 4a and the outer peripheral guide 4b. When the inert gas is injected vertically upward, the inert gas collides vertically with the cover member 5 provided above. In the plan view shown in FIG. 2, the longitudinal width of the injection port 34a is set wider than the width of the semiconductor wafer 2 supported by the semiconductor wafer support portion 4a. More specifically, it is provided wider than the diameter of the semiconductor wafer support portion 4a.

[0022] The rectifying guide 35 includes a main guide portion 35a erected on the opposite side of the semiconductor wafer support portion 4a along the injection port 34a, and side guide portions 35b provided from both ends of the main guide portion 35a toward the semiconductor wafer support portion 4a. A gap is formed between the upper portions of the main guide portion 35a and the side guide portions 35b and the cover member 5.

[0023] According to the stage-side gas supply means 31 having the above configuration, an inert gas flow shown in FIGS. 1 and 2 can be formed between the bonding stage 4 and the cover member 5. That is, when an inert gas is supplied from the inert gas supply source 33 to the nozzle 34, in the side view shown in FIG. 1, the inert gas flowing through the nozzle 34 is jetted vertically upward from the injection port 34a formed at the same height as the semiconductor wafer support portion 4a. The inert gas jetted from the injection port 34a in this way diffuses horizontally when it collides with the cover member 5, and most of it (for example, about 80%) is guided by the rectifying guide 35 and forms a one-way flow from the left side to the right side in the drawing that covers the entire semiconductor wafer 2 held on the right side in the drawing. On the other hand, the inert gas diffused toward the left side in the drawing is discharged to the outside of the rectifying guide 35 from the gap between the rectifying guide 35 and the cover member 5, thereby preventing the external atmosphere located on the left side in the drawing from entering between the cover member 5 and the bonding stage 4.

[0024] As shown in FIG. 4, the head-side gas supply means 32 that constitutes the atmosphere gas replacement means 10 includes an inert gas supply source 33, a reducing gas supply source 36 that supplies a reducing gas as the atmosphere gas, and these inert gas supply source 33 and reducing gas supply source 36. It is connected and is constituted by a frame 37 that further surrounds the outer periphery of the holder 23c that constitutes the tool base 23. The reducing gas supply source 36 is configured to supply a reducing gas such as hydrogen or formic acid. When bonding the electronic component 1 to the semiconductor wafer 2, when a reducing gas is supplied between the bonding stage 4 and the cover member 5, the reducing gas reduces the oxide film remaining on the solder bump B. And the reducing gas supply source 36 is configured to allow the reducing gas to flow into a pipe provided between the inert gas supply source 33 and the bonding head 7 via a solenoid valve 38. The frame 37 has a substantially U-shaped cross section with the opening 5a facing inward. A space that surrounds the holder 23c endlessly is formed between the frame 37 and the outer peripheral surface of the holder 23c. The inert gas supply source 33 and the reducing gas supply source 36 are connected to the space via a gas passage Rb formed in the frame 37.

[0025] As shown in FIG. 4, the gas passages Rb are provided at the four corners of the frame 37 and are connected to the respective gas passages Rb via branch pipes from the inert gas supply source 33 and the reducing gas supply source 36. And at the lower part of the frame 37, slits SL and SS are formed between the frame 37 and the outer peripheral surface of the holder 23c. The slits SL and SS communicate with the space formed inside the frame 37, so that the atmosphere gas in which the inert gas and the reducing gas supplied to the space are mixed is jetted downward. As shown in FIG. 4, the slits SL and SS are provided at positions corresponding to the respective sides of the tool base 23 having a substantially square shape. More specifically, they are formed in a substantially square shape endlessly along the outer peripheral edge of the holder 23c. In the bonding apparatus 3 of this embodiment, a wide slit SL is provided on the left side in the drawing, and the other three positions are narrow slits SS. The opening area of the wide slit SL is set to be, for example, about 10 times that of the narrow slit SS. With such a configuration, it is possible to inject the atmosphere gas from the wide slit SL at a larger flow rate than the narrow slit SS.

[0026] According to the head-side gas supply means 32 having the above configuration, the atmosphere gas supplied from the inert gas supply source 33 and the reducing gas supply source 36 is supplied to the space formed inside the frame 37 through the gas passage Rb, and is injected downward from the slits SL and SS formed between the frame 37 and the holder 23c. As shown in FIG. 3, when the atmosphere gas injected from the slits SL and SS collides with the surface of the semiconductor wafer 2 or the bonding stage 4 located below, it flows along the semiconductor wafer 2 or the bonding stage 4 so as to spread. At this time, the atmosphere gas discharged from the wide slit SL with a large ejection flow rate flows toward the narrow slit SS with a small ejection flow rate, and forms a flow that crosses the electronic component 1 below the bonding head 7. The flow of the atmosphere gas by the head-side gas supply means 32 formed in this way is the same as the flow of the atmosphere gas from the left side to the right side in the drawing formed by the stage-side gas supply means 31 between the bonding stage 4 and the cover member 5.

[0027] As shown in FIG. 1, the electronic component supply stage 9 is provided above the cover member 5 and below the bonding head 7 located at the end of the X-direction rail 13 of the moving means 8. Although not shown, the electronic component supply stage 9 is provided with photographing means so as to recognize the position of the electronic component 1 adsorbed and held by the bonding head 7.

[0028] Hereinafter, the operation of the bonding apparatus 3 having the above configuration will be described. Here, in each state described below, the stage-side gas supply means 31 and the head-side gas supply means 32 that constitute the atmosphere gas replacement means 10 are constantly injecting an inert gas by the inert gas supply source 33. As a result, an inert gas flow is formed between the bonding stage 4 and the cover member 5 by the stage-side gas supply means 31, and the periphery of the mounting position of the electronic component 1 has been replaced with an inert gas. The head-side gas supply means 32 is not constantly supplying a reducing gas, and the supply of the reducing gas is controlled by the control means C as described below.

[0029] First, using FIG. 3, a bump reformation process for removing the oxide film from the solder bumps B of the semiconductor wafer 2 will be described. First, the moving means 8 has separated the bonding head 7 from the opening 5a of the cover member 5. One bonding head 7 is in the middle of moving from the immediately preceding bonding process to one electronic component supply stage 9, and the other bonding head 7 is in a standby state of adsorbing and holding a new electronic component 1 on the other electronic component supply stage 9. On the other hand, the semiconductor wafer 2 is supplied to a predetermined position of the bonding stage 4. Below the opening 5a of the cover member 5, there is an electrode 2a to which the electronic component 1 is not bonded, and a solder bump B with an oxide film formed thereon is formed above it. At this time, the opening 5a of the cover member 5 is closed by the shutter member 12a, the outflow of the atmosphere gas from the opening 5a of the cover member 5 is prevented, and the state where the periphery of the position where the electronic component 1 is bonded is replaced with an inert gas is maintained. On the other hand, since the two bonding heads 7 are moving to positions separated from the opening 5a, the head-side gas supply means 32 provided on these bonding heads 7 has stopped supplying the reducing gas.

[0030] Next, the control means C controls the laser light irradiation means 6 to irradiate the bonding stage 4 with the laser light L. Then, the laser light L passes through the transparent shutter member 12a that closes the opening 5a of the cover member 5 and is irradiated onto the solder bump B of the semiconductor wafer 2. In this embodiment, the output of the laser light L is set to 300 to 450 W, the wavelength is set to 940 to 1020 nm, and the semiconductor wafer 2 is irradiated with the laser light L for 5 seconds. Then, while measuring the temperature by temperature measuring means 16 (not shown), the solder bump B is heated to the target temperature of 290°C. As a result, the solder bump B formed on the electrode 2a of the semiconductor wafer 2 melts, and the oxide film formed on the surface is buried in the molten solder or evaporated and removed. Also, when the solder melts, the upper part thereof is deformed into a substantially spherical shape due to surface tension. Thereafter, when the irradiation of the laser light L by the laser light irradiation means 6 stops, the solder bump B solidifies by cooling. However, since the periphery of the position where the electronic component 1 is joined is replaced with an inert gas, an oxide film is not formed on the surface of the solder bump B.

[0031] FIG. 6 shows a state in which the bonding head 7 holding the new electronic component 1 is moving from the electronic component supply stage 9 above the opening 5a of the cover member 5 by the X-direction moving means 14 of the moving means 8. At this time, since the housing 21 is positioned above the cover member 5 by the elevating means 15, the hood 26 provided outside the housing 21 is in a state of moving downward due to its own weight. Also at this time, the opening 5a of the cover member 5 is closed by the shutter member 12a, and since the stage-side gas supply means 31 continues to form a flow of inert gas between the bonding stage 4 and the cover member 5, the periphery of the position where the electronic component 1 is joined in the semiconductor wafer 2 is replaced with an inert gas.

[0032] FIG. 7 shows a state in which the bonding head 7 is positioned above the opening 5a of the cover member 5, and in this state, the lifting means 15 has slightly lowered the bonding head 7. At this time, the opening 5a is closed by the shutter member 12a. When the bonding head 7 descends, the lower end of the hood 26 abuts against the upper surface of the shutter housing member 12c of the cover member 5. Therefore, only the bonding head 7 descends with respect to the hood 26, and the seal member 26a is separated from the flange portion 21a. As a result, the space above the cover member 5 is partitioned from the outside by the shutter member 12a, the bonding head 7, and the hood 26. In this state, the head-side gas supply means 32 starts supplying a reducing gas, and the inside of the space is filled with the reducing gas.

[0033] When the head-side gas supply means 32 supplies a reducing gas to the space inside the hood 26, an operation of bonding the electronic component 1 to the semiconductor wafer 2 is performed as shown in FIG. 4. First, the shutter means 12 opens the opening 5a, and then the bonding head 7 is lowered to bring the electrode 1a of the held electronic component 1 into contact with the solder bump B formed on the electrode 2a of the semiconductor wafer 2. At this time, an inert gas supplied by the head-side gas supply means 32 and a reducing gas supplied by the stage-side gas supply means 31 are flowing in the space around the electronic component 1 and the semiconductor wafer 2. Further, although a slight gap is formed between the opening 5a of the cover member 5 and the housing 21 of the bonding head 7, the gap is located inside the hood 26 provided so as to surround the housing 21 and is partitioned from the space above the cover member 5. Therefore, external air is prevented from entering the periphery of the position where the electronic component 1 is bonded.

[0034] When the electronic component 1 contacts the semiconductor wafer 2 in this way, the control means C controls the laser light irradiation means 6 to irradiate the laser light L toward the electronic component 1. The laser light L passes through the bonding head 7 and the tool base 23 and heats the bonding tool 22 adsorbed and held on the lower surface of the tool base 23. In this embodiment, the output of the laser light L is set to 300 to 450 W, the wavelength is set to 940 to 1020 nm, and the laser light L is irradiated for 30 to 50 seconds. Then, while measuring the temperature by the temperature measuring means 16, the bonding tool 22 is heated to the target temperature of 290 to 320 °C. When the bonding tool 22 is heated by the laser light L and the electronic component 1 is further heated by heat conduction, the solder bump B in contact with the electrode 2a of the electronic component 1 is heated and melted, and the electronic component 1 and the semiconductor wafer 2 are joined. At this time, by forming the upper part of the solder bump B into a spherical shape in the bump reformation process shown in FIG. 3, it becomes easier for all the electrodes 2a of the electronic component 1 to come into contact with all of the solder bumps B, and even if there is some inclination or warping during heating between the electronic component 1 and the semiconductor wafer 2, the joining can be made more reliably. In addition, the reducing gas supplied by the reducing gas supply source 36 can reduce the oxide film remaining on the melted solder bump B and also reduce the newly generated oxide film.

[0035] When the electronic component 1 is joined to the semiconductor wafer 2 in this way, the control means C controls the moving means 8 to raise the bonding head 7 to the position shown in FIG. 7, and the shutter means 12 closes the opening 5a. Thereafter, after raising the bonding head 7 to the height shown in FIG. 6, in order to hold a new electronic component 1, it moves to the electronic component supply stage 9 on the right side in the drawing. However, since the opening 5a is closed by the shutter means 21, the flow of the inert gas between the bonding stage 4 and the cover member 5 is maintained. On the other hand, while the above-described operation is being performed on the bonding head 7 provided on the left side in the figure, a new electronic component 1 is held and in a standby state on the electronic component supply stage 9 provided on the left side in the figure. Further, the control means C operates the bonding stage 4 to move the electrode 2a for bonding the new electronic component 1 to the bonding position with the electronic component 1, and then uses the bonding head 7 provided on the left side in the figure to repeat the operation for bonding the new electronic component 1 according to the procedure shown in FIG. 3.

[0036] As described above, according to the bonding apparatus of the present embodiment, since the laser light irradiation means 6 is provided above the opening 5a of the cover member 5, the bonding head 7 can be moved from the opening 5a of the cover member 5, and while the electronic component 1 is held by the bonding head 7, the bump reformation process shown in FIG. 3 can be performed. At that time, shutter means 12 for opening and closing the opening 5a is provided in the cover member 5, and by using a transmissive member that allows the laser light L to pass through the shutter member 12a, it is possible to irradiate the semiconductor wafer 2 with the laser light L while preventing the inflow of air from the opening 5a as shown in FIG. 3. Also, in the bump reformation process of FIG. 3, the bonding head 7 can be moved toward the electronic component supply stage 9 to hold a new electronic component 1, and by performing the bump reformation process during the holding operation of the electronic component 1, bonding can be performed efficiently.

[0037] In the above embodiment, as shown in FIG. 4, the electronic component 1 held by the bonding head 7 is brought into contact with the semiconductor wafer 2, and in this state, the laser light irradiation means 6 irradiates the laser light L to heat the electronic component 1 and bond it to the semiconductor wafer 2. On the other hand, as shown in FIG. 8, when the bonding head 7 places the electronic component 1 on the upper part of the semiconductor wafer 2, it detaches from the opening 5a of the cover member 5, and the shutter means 12 closes the opening 5a. In that state, the laser light irradiating means 6 may irradiate the laser light L, transmit it through the shutter member 12a, and heat the electronic component 1 and the semiconductor wafer 2 positioned below to melt and bond the solder bumps B. Even in this case, since the opening 5a of the cover member 5 is closed by the shutter means 5, the inflow of outside air from the opening 5a is blocked, and oxidation of the solder bumps B is prevented. Also, during the bonding between the electronic component 1 and the semiconductor wafer 2, the bonding head can be moved to hold a new electronic component 1, so that bonding can be performed efficiently.

[0038] In the above embodiment, the shutter means 12 is provided on the upper surface of the cover member 5, but it may be provided on the lower surface of the cover member 5. In that case, the hood 26 provided on the bonding head 7 will contact the periphery of the opening 5a of the cover member 5.

Explanation of Reference Numerals

[0039] 1 Electronic component 2 Semiconductor wafer (substrate) 3 Bonding apparatus 4 Bonding stage 5 Cover member 5a Opening 6 Laser light irradiating means 7 Bonding head 12 Shutter means 12a Shutter member 26 Hood B Solder bump L Laser light

Claims

1. A bonding apparatus comprising: a bonding stage for holding a substrate having solder bumps formed thereon; a laser light irradiation means for irradiating a laser beam; a bonding head for transmitting the laser beam and holding an electronic component; a moving means for relatively moving the bonding stage and the bonding head; a cover member disposed above the bonding stage and having an opening through which the bonding head can pass; a shutter means having a shutter member for opening and closing the opening; a stage-side gas supply means for supplying an atmospheric gas between the cover member and the bonding stage; and a control means for controlling these components, wherein the laser light irradiation means is provided above the opening of the cover member such that the laser beam irradiated by the laser light irradiation means passes through the opening, and at least a part of the shutter member of the shutter means is constituted by a transmissive member through which the laser beam can pass, and the control means irradiates the laser beam by the laser light irradiation means in a state where the opening of the cover member is closed by the shutter means, the bonding head is retracted from the opening by the moving means, and the laser beam is irradiated onto the substrate held on the bonding stage through the transmissive member of the shutter member.

2. The control means irradiates the laser beam by the laser light irradiation means in a state where the opening of the cover member is closed by the shutter means, the bonding head is retracted from the opening by the moving means, and the electronic component is not placed on the substrate, thereby heating and melting the solder bumps formed on the substrate and removing the oxide film on the surface of the solder bumps. The bonding apparatus according to claim 1.

3. When the control means moves the bonding head holding the electronic component above the opening of the cover member by the moving means, the shutter means opens the opening of the cover member, and when the bonding head is further lowered by the moving means and the electronic component comes into contact with the substrate, the laser light irradiation means irradiates the laser beam to heat the electronic component and bond the electronic component to the substrate. The bonding apparatus according to claim 1.

4. The bonding apparatus according to claim 1, wherein the control means irradiates a laser beam by a laser beam irradiation means to heat the electronic component and bond the electronic component and the substrate in a state where the opening of the cover member is closed by the shutter means, the bonding head is retracted from the opening by the moving means, and the electronic component is placed on the substrate.

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