Soldering device and manufacturing method of semiconductor device

Abstract

To inhibit voids from occurring due to an alloy layer to reduce defects in a solder layer in a semiconductor device.SOLUTION: A soldering device 10 includes: a semiconductor element heating part 14 which heats a semiconductor element 21 to a temperature higher than a melting point of solder; a solder supply part 15 which supplies melted solder 22b to an entire joint area on a rear surface of the semiconductor element 21; and a transport part 17 which holds and moves the semiconductor element 21. The transport part 17 presses the melted solder 22b supplied to the rear surface of the semiconductor element 21 to a substrate 23 to join the semiconductor element 21 and the substrate 23 to each other and form a semiconductor device 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a soldering apparatus and a method for manufacturing a semiconductor device. [Background technology]

[0002] In the soldering process for manufacturing semiconductor devices, the semiconductor element and the board, or the board and the base are surface-joined with solder. In the case of the semiconductor element and the board, the molten solder first wets the main surfaces of the semiconductor element and the board. After that, the solder is cooled below its melting point to form a solder layer between the two main surfaces. In the case of the soldering between the board and the base, a solder layer is basically formed between the two main surfaces in the same way. However, since the power semiconductor element has a limited upper limit of operating temperature and needs to dissipate heat through the solder layer, it is necessary to avoid the occurrence of defects such as voids that hinder heat dissipation in the solder layer directly under the power semiconductor element.

[0003] A common soldering method is to use a solder paste and supply the solder by printing. The flux components contained in the solder paste may generate gas. If the generated gas does not escape to the outside of the area formed between the two opposing main surfaces to be soldered, it will remain in the solder layer as voids after the soldering process.

[0004] Another method is a soldering method in which solder is supplied under a reducing atmosphere using plate-shaped solder (preform solder). During the soldering process, a reducing gas is supplied into the soldering device to remove the oxide film present on the back surface of the semiconductor element, the front surface (semiconductor element side) and back surface (substrate side) of the plate-shaped solder, and each of the main surfaces of the substrate surface. After or at the same time as removing the oxide film, the solder is melted to obtain a solder layer. However, gases such as water vapor and carbon dioxide may be generated during the reaction between the oxide film and the reducing gas, hydrogen or formic acid. If the generated gas remains in the region formed between the two main surfaces and is cooled and solidified, it will become a void. In addition, since the solder is solidified once after being molded into a plate shape, the solder itself will oxidize. As a result, if the subsequent reduction is not performed sufficiently, the oxide film may be incorporated into the solder layer, causing the quality of the solder layer to deteriorate.

[0005] Patent Document 1 discloses a soldering method using molten solder, in which a semiconductor element is placed on molten solder supplied onto a substrate and bonded thereto.

[0006] Soldering methods using molten solder can suppress the formation of an oxide film by keeping the solder in a molten state at all times, and therefore produce a more stable quality solder layer than methods that allow the solder to solidify. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2004-281646 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the soldering method described in Patent Document 1, after the molten solder is supplied onto the board and before the semiconductor element is mounted, the interface between the periphery of the molten solder and the board reacts to form an alloy layer. In particular, if time passes while the molten solder does not wet and spread over the entire joining area on the board, an alloy layer is formed in the joining area. If this alloy layer oxidizes, non-wetting occurs when the molten solder wets and spreads after the semiconductor element is mounted, which causes voids to form in the solder layer.

[0009] The present disclosure has been made to solve the above-mentioned problems, and aims to suppress the occurrence of voids caused by the alloy layer and reduce defects in the solder layer. [Means for solving the problem]

[0010] The soldering apparatus disclosed herein is a soldering apparatus for a semiconductor device that bonds a semiconductor element onto a substrate via solder, and is characterized in that it comprises a semiconductor element heating section that heats the semiconductor element to a temperature above the melting point of the solder, a solder supply section that supplies molten solder to the entire bonding area on the back surface of the semiconductor element, and a transport section that holds and moves the semiconductor element, wherein the transport section presses the molten solder supplied to the back surface of the semiconductor element against the substrate to bond the semiconductor element and the substrate. Effect of the Invention

[0011] According to the soldering apparatus of the present disclosure, it is possible to suppress the occurrence of voids caused by the alloy layer and reduce defects in the solder layer. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view of a soldering apparatus according to a first embodiment. [Diagram 2] 3 is a schematic cross-sectional view showing a semiconductor element heating step in the semiconductor manufacturing method according to the first embodiment. FIG. [Diagram 3] 3 is a schematic cross-sectional view showing a solder supplying step of the semiconductor manufacturing method according to the first embodiment. [Figure 4]3 is a schematic cross-sectional view showing a solder supplying step of the semiconductor manufacturing method according to the first embodiment. [Diagram 5] 1 is a schematic cross-sectional view showing a solder supplying step of a semiconductor manufacturing method according to a first embodiment; [Figure 6] 1 is a schematic cross-sectional view showing a bonding step in a semiconductor manufacturing method according to a first embodiment. [Figure 7] 1 is a schematic cross-sectional view showing a solder supplying step in a semiconductor manufacturing method according to a conventional technique. [Figure 8] FIG. 1 is a schematic cross-sectional view showing a bonding step in a semiconductor manufacturing method according to a conventional technique. [Figure 9] 1 is a schematic cross-sectional view showing a bonding step in a semiconductor manufacturing method according to a conventional technique. [Figure 10] 10 is a schematic cross-sectional view showing a solder supplying step of a semiconductor manufacturing method using a soldering apparatus according to a modified example of the first embodiment. FIG. [Figure 11] 10 is a schematic cross-sectional view showing a bonding step in a semiconductor manufacturing method according to a modified example of the first embodiment. [Figure 12] 10 is a schematic cross-sectional view showing a bonding step in a semiconductor manufacturing method according to a modified example of the first embodiment. [Figure 13] 11 is a schematic cross-sectional view showing a solder supplying step of a semiconductor manufacturing method using a soldering apparatus according to a second embodiment. FIG. [Figure 14] 11 is a schematic cross-sectional view showing a solder supplying step of a semiconductor manufacturing method using a soldering apparatus according to a second embodiment. FIG. [Figure 15] 11 is a schematic cross-sectional view showing a solder supplying step of a semiconductor manufacturing method using a soldering apparatus according to a third embodiment. FIG. [Figure 16] 11 is a schematic cross-sectional view showing a solder supplying step of a semiconductor manufacturing method using a soldering apparatus according to a third embodiment. FIG. [Figure 17] 11 is a schematic cross-sectional view showing a solder supplying step of a semiconductor manufacturing method using a soldering apparatus according to a third embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Embodiment 1 The first embodiment will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a soldering apparatus 10 according to the first embodiment. For convenience of explanation, the positional relationship of each component of the soldering apparatus 10 will be described using an XYZ Cartesian coordinate system defined by mutually orthogonal X-axis, Y-axis, and Z-axis. Each of the X-axis direction and the Y-axis direction is a horizontal direction (i.e., a predetermined direction in a horizontal plane), and the Z-axis direction is a vertical direction (i.e., a direction perpendicular to the horizontal plane, and essentially a vertical direction or a direction of gravity). In the following explanation, the direction perpendicular to the paper surface is the X-axis, the direction toward the back of the paper surface is the X-axis direction negative side, and the direction toward the front of the paper surface is the X-axis direction positive side. In addition, the lower side in the Z-axis direction, i.e., the Z-axis direction negative side, will be simply called the lower side, and the upper side in the Z-axis direction, i.e., the Z-axis direction positive side, will be simply called the upper side.

[0014] As shown in FIG. 1, the soldering apparatus 10 includes a heating furnace 11, and a semiconductor element heating section 14, a solder supply section 15, a transport section 17, and a mesh conveyor 12, all of which are installed within the heating furnace 11.

[0015] In this embodiment, the heating furnace 11 is a tunnel furnace. A reducing atmosphere is maintained inside the heating furnace 11. The inlet side of the heating furnace 11 is the positive side in the X-axis direction, and the outlet side of the heating furnace 11 is the negative side in the X-axis direction.

[0016] The mesh conveyor 12 conveys the substrate 23 placed on the pallet 13 on the mesh conveyor 12 so as to move from the entrance to the exit of the heating furnace 11. After the substrate 23 enters the heating furnace 11, the oxide film is reduced according to a predetermined temperature profile, and then the substrate 23 enters the melting zone and is heated to a temperature equal to or higher than the melting point of the solder. FIG. 1 shows a cross-sectional view of the melting zone in the direction connecting the entrance and exit of the heating furnace 11. In the melting zone in the heating furnace 11, a semiconductor element 21 is mounted on the substrate 23 on the mesh conveyor 12 via solder to form a semiconductor device 20. The formed semiconductor device 20 is conveyed to the exit of the heating furnace 11 via a cooling zone (not shown) in the heating furnace 11.

[0017] The semiconductor device 20 includes a substrate 23 and a semiconductor element 21 mounted on the substrate 23 via solder. An electrode is formed on the back surface of the semiconductor element 21. The electrode is made of, for example, Au, which is a material that easily wets and spreads with solder.

[0018] The semiconductor element heating section 14 heats the semiconductor element 21 before bonding to a temperature equal to or higher than the melting point of the solder. In this embodiment, the semiconductor element heating section 14 is a heating tray.

[0019] The solder supply unit 15 supplies the molten solder 22b to the back surface of the semiconductor element 21. In this embodiment, a transfer jig is used as the solder supply unit 15. The transfer jig melts the solid solder 22a sent by the solder feeder 16, and supplies the molten solder 22b to the entire bonding area on the back surface of the semiconductor element 21. That is, the solder on the transfer jig is transferred to the back surface of the semiconductor element 21, thereby supplying the molten solder 22b to the back surface of the semiconductor element 21. Here, the bonding area is an area corresponding to the size of the final solder layer after bonding. The transfer jig also includes a heating mechanism for melting the solid solder 22a. The heating mechanism is, for example, a rod-shaped cartridge heater or a hot plate. The transfer jig is preferably made of aluminum or stainless steel, which is a material that is not wetted by solder. Since the solder does not wet the transfer jig, the molten solder 22b does not remain on the transfer jig, and can be entirely supplied to the back surface of the semiconductor element 21. Here, the non-wetting state refers to a state in which the contact angle, which is the angle between the tangent of the solder droplet and the main surface of the transfer jig, is 90 degrees or more.

[0020] The conveying section 17 holds the semiconductor element 21 and conveys the semiconductor element 21 onto the semiconductor element heating section 14, the solder supplying section 15, and the mesh conveyor 12. The conveying section 17 presses the molten solder 22b supplied to the rear surface of the semiconductor element 21 against the substrate 23, thereby bonding the semiconductor element 21 and the substrate 23. In this embodiment, a metal suction collet is used as the conveying section 17. In addition, in order to prevent the molten solder 22b supplied to the rear surface of the semiconductor element 21 from solidifying, it is preferable that the conveying section 17 is provided with a heating mechanism capable of raising the temperature of the held semiconductor element 21 to a temperature equal to or higher than the melting point of the solder. When the conveying section 17 is provided with a heating mechanism, the heating mechanism may be used as the semiconductor element heating section instead of the heating tray described above.

[0021] Next, a semiconductor manufacturing method using the soldering apparatus 10 will be described in detail with reference to Figures 2 to 6. The semiconductor manufacturing method includes a semiconductor element heating step, a solder supplying step, and a bonding step. The semiconductor element heating step will be described with reference to Figure 2, the solder supplying step with reference to Figures 3 to 5, and the bonding step with reference to Figure 6.

[0022] 2, in the semiconductor element heating step, the semiconductor element 21 before solder supply is placed on a heating tray serving as the semiconductor element heating unit 14 and heated to a temperature equal to or higher than the melting point of the solder. Next, the semiconductor element 21 heated by the semiconductor element heating unit 14 is attracted from above and held by the conveying unit 17. Here, as described above, if a heating mechanism is attached to the conveying unit 17, the heating mechanism may be used as the semiconductor element heating unit instead of the heating tray. In this case, after the semiconductor element 21 is held by the conveying unit 17, the semiconductor element 21 can be heated to a temperature equal to or higher than the melting point of the solder by the heating mechanism attached to the conveying unit 17.

[0023] In the solder supplying process, first, as shown in Fig. 3, the solder feeder 16 feeds the solid solder 22a from above to the transfer jig. In this embodiment, the solder feeder 16 cuts off the thread-like solid solder 22a at a fixed length and feeds it onto the transfer jig, but solid solder 22a molded into a sphere or pellet may also be used. An oxide film is formed on the surface of the solid solder 22a that is fed onto the transfer jig and heated, but since reducing gas circulates within the heating furnace 11, the oxide film is reduced and melted by the reducing gas. As shown in Fig. 4, the molten solder is repelled by the transfer jig and becomes spherical.

[0024] 5, the semiconductor element 21 held by the conveyor 17 is conveyed onto a transfer jig, and while still held, is pressed from above against the molten solder 22b on the transfer jig, thereby supplying the molten solder 22b onto the rear surface of the semiconductor element 21. After coming into contact with the rear surface of the semiconductor element 21, the molten solder 22b quickly spreads over the entire bonding area on the rear surface of the semiconductor element 21.

[0025] 6, in the bonding process, the semiconductor element 21 held by the conveying unit 17 is conveyed onto the substrate 23, and the semiconductor element 21 to which the solder has been supplied is pressed against the substrate 23 from above to spread the solder on the substrate 23. Furthermore, in order to discharge gas entrained when the solder is spread on the substrate 23, the semiconductor element 21 held by the conveying unit 17 is scrubbed in the horizontal direction (XY direction) relative to the substrate 23 while the solder is melted and both of the main surfaces of the semiconductor element 21 and the substrate 23 are wet. Next, the semiconductor device 20 in which the semiconductor element 21 and the substrate 23 are bonded via the solder is conveyed by the mesh conveyor 12 to a cooling zone (not shown) in the heating furnace 11, where the solder is solidified to complete the bonding.

[0026] For comparison with the soldering apparatus 10 of the present embodiment, a soldering process by a soldering apparatus using molten solder of the prior art is shown as a comparative example in Figs. 7 to 9. In the comparative example, first, as shown in Fig. 7, molten solder 22b is sucked from a solder tank by a syringe 30 and discharged from above onto the substrate 23, thereby supplying the molten solder 22b onto the substrate 23. At this point, the molten solder 22b has not spread over the entire bonding area on the substrate 23. Next, as shown in Fig. 8, the semiconductor element 21 held by the conveying unit 17 is pressed against the molten solder 22b on the substrate 23 from above, so that the molten solder 22b is spread over the entire bonding area between the semiconductor element 21 and the substrate 23 and bonded to each other as shown in Fig. 9.

[0027] In the soldering process of the comparative example described above, the molten solder 22b supplied onto the substrate 23 reacts with the substrate 23 over time until the semiconductor element 21 is mounted, forming an alloy layer 31. In particular, the alloy layer 31 may be formed so as to spread from the end of the molten solder 22b to the outside of the substrate 23 in the XY direction. This alloy layer 31 is not wetted by the solder, and therefore becomes a non-wetted portion to which the solder does not bond. If the solder is spread after the alloy layer 31 is formed, a non-wetted portion will be formed within the bonding area on the surface of the substrate 23. If the gas entrapped in the molten solder 22b during the process of spreading the molten solder 22b is adsorbed to the non-wetted portion, a solder void 32 will be formed within the solder layer. Although there is a method of scrubbing the semiconductor element 21 horizontally (in the XY direction) relative to the substrate 23 in order to discharge the entrapped gas, it is difficult to forcibly discharge the gas adsorbed in the non-wetted portion only by the flow of the solder caused by the scrub.

[0028] In the soldering apparatus 10 of this embodiment, the molten solder is supplied to the rear surface of the semiconductor element 21, and the molten solder is spread over the entire bonding area on the rear surface of the semiconductor element 21 before an alloy layer is formed around the end of the molten solder, thereby suppressing the occurrence of solder voids in the solder layer. In other words, since the alloy layer, i.e., the non-wetted portion, is not formed in the bonding area, the occurrence of solder voids formed by gases and the like entrained during wetting and spreading being adsorbed by the non-wetted portion can be suppressed. This makes it possible to form a high-quality solder layer with few defects such as voids. Furthermore, by being able to form a high-quality solder layer with few defects such as voids, it is possible to reduce waste and inspection work due to soldering defects.

[0029] In addition, the soldering apparatus 10 of the present embodiment supplies the molten solder to the back surface of the semiconductor element 21, so that the molten solder can be spread over the entire bonding area more easily than when the molten solder is supplied to the substrate 23 side. When the molten solder is supplied to the substrate 23 side, since the surface of the substrate 23 is made of copper and the solder does not easily spread, in order to spread the solder over the entire bonding area on the substrate 23, it is necessary to add a separate physical operation such as forming the supplied solder with a jig and spreading it over the entire bonding area. Even if the solder is spread over the entire bonding area on the substrate 23 by applying the above-mentioned physical operation, there is also a problem that voids are likely to occur when the semiconductor element 21 is placed on the spread solder on the substrate 23 due to the inclusion of surrounding air. In contrast, when molten solder is supplied to the rear surface of the semiconductor element 21 as in this embodiment, the rear electrode of the semiconductor element 21 is made of Au or the like, which is easily wetted and spread by solder, and when the molten solder is supplied to the rear surface of the semiconductor element 21, it quickly wets and spreads over the entire bonding area on the rear surface of the semiconductor element 21, so that the molten solder can be easily spread over the entire bonding area without performing any additional physical operations. Therefore, the soldering process can be simplified while suppressing the generation of voids.

[0030] Furthermore, the soldering apparatus 10 of the present embodiment performs soldering by constantly maintaining the melted solder in a molten state, which makes it possible to suppress the formation of an oxide film and stabilize the quality of the solder layer, compared to the case where the solder is solidified. In addition to the above-mentioned effect of suppressing the occurrence of voids, it is also possible to suppress the formation of an oxide film, thereby further improving the quality of the solder layer. It is possible to perform highly reliable soldering for products that require a higher quality solder layer, such as products for in-vehicle use.

[0031] Next, a modified example of the first embodiment will be described. As shown in FIG. 5, the shape of the molten solder 22b after being supplied to the back surface of the semiconductor element 21 is preferably a convex shape with its apex located at the center of the back surface of the semiconductor element 21. When the molten solder 22b is supplied to the center of the back surface of the semiconductor element 21, a convex shape is formed by the surface tension of the molten solder 22b. After that, the molten solder 22b wets and spreads uniformly in the horizontal direction from the center of the semiconductor element 21, so that the apex of the convex portion is located at the center of the back surface of the semiconductor element 21. In this state, when the semiconductor element 21 to which the molten solder 22b has been supplied is pressed against the substrate 23, the apex of the convex portion of the molten solder 22b first comes into contact with the surface of the substrate 23, and then the molten solder 22b wets and spreads on the surface of the substrate 23 with the apex of the convex portion as the center. By wet-spreading from the center outward, a solder layer can be formed between the semiconductor element 21 and the substrate 23 without involving surrounding gas.

[0032] As shown in FIG. 10, it is preferable to provide a taper 40 on the main surface of the transfer jig on which the solder is placed, to form a concave shape, and to set the apex of the taper 40 at the center of the main surface of the transfer jig. By providing the taper 40, the solid solder is positioned at the bottom of the concave portion. When supplying solder to the semiconductor element 21, the center of the back surface of the semiconductor element 21 and the apex of the taper 40, which is the center of the concave portion of the transfer jig main surface, are aligned, so that the solder can be placed at the center of the back surface of the semiconductor element 21. Also, if the height of the groove formed by the taper 40 is higher than the molten solder 22b that has become a sphere, it will not be possible to supply the solder to the semiconductor element 21, so it is preferable that the height is lower than the diameter of the molten solder 22b. Here, the joining area is set to an area corresponding to the entire back surface of the semiconductor element 21. For example, when the semiconductor element 21 is 10×10 mm and the thickness of the solder is 0.1 mm, the volume of the required solder is 10 mm. 3 When this solder becomes a sphere, the diameter will be about 2.7 mm, so the depth of taper 40 needs to be less than 2.7 mm. As described above, by providing taper 40 on the main surface of the transfer jig, the occurrence of voids can be further suppressed.

[0033] 11 and 12, it is preferable to provide a spacer between the semiconductor element 21 and the substrate 23 in the bonding process. For example, protrusions 41 or Ni balls 42 that do not melt at the soldering temperature can be used as the spacer. By using the spacer to keep the distance between the semiconductor element 21 and the substrate 23 at a certain level or more, the thickness of the solder layer is kept at a certain level or more. This effectively prevents the solder placed between the semiconductor element 21 and the substrate 23 from being pushed out from between the two main surfaces by excessive pressure applied by the operation of the conveying unit 17. That is, the volume between the two main surfaces is the area of ​​the two main surfaces multiplied by the distance between the two main surfaces, but if the distance between the two main surfaces becomes too small, the volume between the two main surfaces becomes smaller than the volume of the solder supplied, and the solder is pushed out of the area between the two main surfaces. When the pressure applied by the conveying unit 17 is removed, the solder tries to return to the original area between the two main surfaces due to surface tension. However, if the extruded volume is large, and the condition that the total surface area is smaller when the two separated and gathered into a sphere than when connected to the region between the two main surfaces is satisfied, the two separated pieces will not return to the original region between the two main surfaces even when the pressure applied by the conveying unit 17 is removed. As a result, a problem occurs in which solder balls are generated. As described above, by providing a spacer between the semiconductor element 21 and the substrate 23, the generation of solder balls due to the pressure application by the conveying unit 17 can be avoided.

[0034] 11 shows an example in which protrusions 41 are used as spacers. Examples of protrusions 41 include wires bonded to substrate 23 in advance, and protrusions 41 obtained by plastic processing of substrate 23. Those skilled in the art use a method such as joining a short Al wire to the position of protrusion 41, or forming protrusions 41 on substrate 23 by press processing. Protrusions 41 act as spacers, making it possible to prevent the distance between the two main surfaces from shrinking below the height of protrusions 41.

[0035] 12 shows an example in which Ni balls 42 are used as spacers. By mixing the solder with Ni balls 42, which are spherical, non-melting spacers that do not dissolve in solder at the soldering temperature, it is possible to prevent the distance between the two main surfaces from shrinking to less than the diameter of the Ni balls 42. The higher the temperature, the faster Ni dissolves in the solder, but complete dissolution can be avoided at soldering temperatures that are common sense for those skilled in the art.

[0036] Moreover, in the above description, the heating furnace 11 is a tunnel furnace, but the heating furnace 11 may be a batch-type chamber furnace, and in this case too, the same effect is achieved.

[0037] Embodiment 2 The soldering device in the second embodiment will be described with reference to Figs. 13 and 14. The soldering device in the second embodiment includes a solder bath 43 for storing molten solder and a syringe 30 for sucking the molten solder 22b in the solder bath 43 and sending the sucked molten solder 22b onto the transfer jig as a means for sending the molten solder 22b to the transfer jig as the solder supply unit 15. The second embodiment differs from the first embodiment in that the solder feeder 16 is used to send the thread-shaped solid solder 22a onto the transfer jig, whereas the syringe 30 is used to send the sucked molten solder 22b onto the transfer jig. In the first embodiment, an oxide film is formed on the surface of the solid solder 22a, and it is necessary to remove the oxide film using a reducing gas before melting the solid solder 22a. However, if the reduction is insufficient, the oxide film is left behind in the molten solder 22b, which causes voids. In contrast, in the soldering apparatus of the second embodiment, the syringe 30 is used to suck the molten solder 22b in the solder bath 43 (FIG. 13), and the sucked molten solder 22b is sent onto the transfer jig (FIG. 14). From then on, the process from supplying the molten solder 22b to the semiconductor element 21 to bonding the semiconductor element 21 and the substrate 23 is the same as in the first embodiment. By sending the molten solder 22b sucked up using the syringe 30 onto the transfer jig, it is possible to suppress the inclusion of an oxide film compared to the case where the solid solder 22a is used. Note that dross 44, which is an oxide film of the solder, may float on the surface of the molten solder 22b in the solder bath 43. In that case, when sucking up the molten solder 22b in the solder bath 43 using the syringe 30, the tip of the syringe 30 is inserted from above so as to penetrate the dross 44, and the molten solder 22b is sucked up, thereby suppressing the inclusion of the dross 44 in the sucked molten solder 22b.

[0038] As described above, in the soldering apparatus of embodiment 2, in addition to providing the same effects as embodiment 1, it is possible to supply molten solder with less oxide film mixed in than in embodiment 1, thereby further suppressing voids.

[0039] Embodiment 3 The soldering device in the third embodiment will be described with reference to Figs. 15 to 17. The soldering device in the third embodiment is different from the first embodiment in that a solder feeder 16 is used instead of a transfer jig as a solder supplying section that supplies molten solder 22b to the back surface of the semiconductor element 21. As shown in Fig. 15, the solder feeder 16 is disposed below (on the back surface side) of the semiconductor element 21 held by the conveying section 17 in the soldering device in the third embodiment. As shown in Fig. 16, the solder feeder 16 feeds a filamentary solid solder 22a to the back surface of the semiconductor element 21 heated to a temperature equal to or higher than the melting point of the solder, and melts the solder to supply the molten solder 22b to the back surface of the semiconductor element 21. The amount of solder to be supplied can be adjusted by the amount of solid solder 22a fed from the solder feeder 16. The molten solder 22b supplied to the back surface of the semiconductor element 21 quickly wets and spreads over the entire bonding area of ​​the back surface of the semiconductor element 21. Molten solder 22b supplied to the rear surface of semiconductor element 21 and solid solder 22a delivered from solder feeder 16 are connected to each other, but as shown in Fig. 17, they are separated by the vertical movement of transport unit 17 and solder feeder 16. Thereafter, semiconductor element 21 and substrate 23 are joined in the same manner as in the first embodiment.

[0040] As described above, the soldering apparatus according to the third embodiment can supply molten solder to the entire joining area on the rear surface of the semiconductor element 21, as in the first embodiment, and therefore can suppress voids caused by the alloy layer. Furthermore, since the solder is supplied directly to the rear surface of the semiconductor element 21 by the solder feeder 16 without using a transfer jig, the soldering can be performed economically in a short time.

[0041] The configurations shown in the above embodiments are merely examples of the contents of the present disclosure, and may be combined with other known techniques. Furthermore, parts of the configurations may be omitted or modified without departing from the scope of the present disclosure. [Explanation of symbols]

[0042] REFERENCE SIGNS LIST 10 soldering device, 11 heating furnace, 14 semiconductor element heating section, 15 solder supply section, 16 solder feeder, 17 conveying section, 20 semiconductor device, 21 semiconductor element, 22a solid solder, 22b molten solder, 23 substrate, 30 syringe, 40 taper, 41 protrusion, 42 Ni ball, 43 solder bath

Claims

1. A soldering apparatus for a semiconductor device that bonds a semiconductor element onto a substrate via solder, comprising: a semiconductor element heating section for heating the semiconductor element to a melting point of the solder or higher; a solder supply unit that supplies molten solder to the entire bonding area on the back surface of the semiconductor element; a transport unit that holds and moves the semiconductor element, The conveying unit presses the molten solder supplied to the rear surface of the semiconductor element against the substrate to bond the semiconductor element and the substrate. Soldering equipment.

2. The electrode on the back surface of the semiconductor element is made of Au.

2. The soldering apparatus according to claim 1.

3. The solder supply unit is a transfer tool that transfers molten solder to the rear surface of the semiconductor element.

2. The soldering apparatus according to claim 1.

4. The apparatus further includes a solder feeder for feeding solid solder onto the transfer jig.

4. The soldering apparatus according to claim 3.

5. a solder bath for storing molten solder; The solder transfer device further includes a syringe that sucks the solder from the solder bath and delivers the sucked solder onto the transfer jig.

4. The soldering apparatus according to claim 3.

6. The transfer jig includes a heating mechanism that heats the solder on the transfer jig to a melting point or higher.

4. The soldering apparatus according to claim 3.

7. The transfer tool is made of a material that is not wettable by solder.

4. The soldering apparatus according to claim 3.

8. a main surface of the transfer jig has a concave shape in which a taper is provided on the main surface; The apex of the taper coincides with the center of the main surface of the transfer jig.

4. The soldering apparatus according to claim 3.

9. The depth of the taper is smaller than the diameter of the molten solder.

9. The soldering apparatus according to claim 8.

10. A method for manufacturing a semiconductor device using the soldering apparatus according to any one of claims 1 to 9, a semiconductor element heating step of heating the semiconductor element to a melting point of the solder or higher; a solder supplying step of supplying molten solder to the entire bonding area on the back surface of the semiconductor element; a bonding step of pressing the molten solder supplied to the rear surface of the semiconductor element against the substrate to bond the semiconductor element to the substrate; A method for manufacturing a semiconductor device comprising the steps of:

11. In the bonding step, a spacer is provided to maintain a certain distance between the semiconductor element and the substrate. The method for manufacturing a semiconductor device according to claim 10.

12. In the solder supplying step, the center of the solder supply portion is aligned with the center of the rear surface of the semiconductor element. The method for manufacturing a semiconductor device according to claim 10.

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