JP6168586B2 - Bonding method and semiconductor module manufacturing method - Google Patents

Description

  The present invention relates to a bonding method and a semiconductor module manufacturing method.

  In recent years, wide-gap semiconductor chips such as SiC and GaN, which have low forward current resistance and high-speed switching performance and can be operated even at a high temperature exceeding 200 ° C., are attracting attention as semiconductor chips used in semiconductor modules such as power modules. . In the semiconductor module using this semiconductor chip, since the heat dissipation structure can be simplified, it is possible to achieve higher density and higher integration. For example, when used in a power module, the power density per unit area is reduced. It can be improved dramatically.

  Conventionally, when a semiconductor chip is mounted on a module substrate to form a semiconductor module, the semiconductor chip is disposed on the module substrate, and an electrode (for example, drain electrode) on the substrate side of the semiconductor chip is die-bonded to form an electrode on the module substrate. In recent years, so-called two-dimensional mounting has been performed in which an electrode (for example, a source / gate electrode) on the surface opposite to the substrate is connected to the electrode of the module substrate by wire bonding (see Patent Document 1). So-called three-dimensional mounting has been proposed in which module substrates are arranged on both sides of a semiconductor chip, and electrodes on both sides of the semiconductor chip are joined to the electrodes of each module substrate. This three-dimensional mounting eliminates the need for wire bonding, and therefore can achieve higher circuit density, space saving, and lower inductance than two-dimensional mounting.

JP 2011-138808 A

  By the way, in the above-described three-dimensional mounting, for example, it is necessary to bond the electrodes of each module substrate to the electrodes on both sides of the semiconductor chip, and it is necessary to sequentially bond a plurality of semiconductor chips to the module substrate. This joining cannot be performed at once, and it is necessary to perform joining several times. For this reason, it is necessary to prepare a plurality of types of solder having different melting points according to the number of times of joining so that the solder once joined does not remelt. However, for example, when a semiconductor chip capable of operating at a high temperature exceeding 200 ° C. as described above is three-dimensionally mounted, a solder having a melting point exceeding 200 ° C. is required so as not to melt at the time of operation. Since there are still few types, it is practically difficult to perform 3D mounting using only solder.

  Therefore, instead of solder, a paste-like bonding agent containing metal particles such as gold of the same material as the surface of the bonding electrode is used instead of solder, and the bonding agent is sintered to bond the electrodes together. I'm thinking of joining. Since the melting point of the bonding agent increases after sintering, it can withstand multiple bonding.

  However, in that case, since it is necessary to apply a bonding agent to the electrodes and apply pressure between the electrodes to sandwich the bonding agent, the bonding agent may protrude laterally from between the electrodes. A semiconductor chip includes adjacent electrodes such as a source electrode and a gate electrode, for example. If the bonding agent protrudes from the electrode, there is a possibility that a short circuit may occur between adjacent electrodes.

  The present invention has been made in view of such points, and in a three-dimensionally mounted semiconductor module in which a module substrate is bonded to both surfaces of a semiconductor chip, the bonding agent is used by using a paste-like bonding agent containing metal particles. It is an object of the present invention to provide a joining method for joining electrodes so that they do not protrude laterally from the electrodes, and a method for manufacturing a semiconductor module using the joining method.

  To achieve the above object, the present invention provides a method for joining at least one module substrate electrode and a semiconductor chip electrode in a semiconductor module in which a module substrate is joined to both surfaces of a semiconductor chip, the semiconductor chip comprising: A step of applying a paste-like bonding agent containing metal particles to each of the electrodes of the module substrate and the electrodes of the module substrate, and forming irregularities on the surface of the bonding agent of one of the semiconductor chip and the module substrate A step of curing the bonding agent with unevenness on the surface, the bonding agent cured with unevenness on the surface of the one electrode of the semiconductor chip and the module substrate, and the other The step of combining the uncured bonding agent of the electrode and the step of sintering the metal particles of the combined bonding agent, It is the case method.

  The step of applying the bonding agent is performed using screen printing in which a screen mask is disposed on the electrode and the paste adhesive is applied to the electrode through the screen mask, thereby forming irregularities on the surface of the bonding agent. The step may be performed by removing the screen mask from the electrode.

  The bonding method further includes a step of pressing the plate-like member against the surface of the bonding agent and aligning the height of the protrusions of the unevenness before the step of curing the bonding agent with the surface being uneven. You may have.

  The height of the convex portion aligned by the plate-like member may be set to a target thickness of the bonding agent that is finally disposed between the electrodes.

The pasty bonding agent has a particle size of 0.05 or more, may be a gold paste having the following gold particles 0.5 [mu] m.

  You may make it join the gate electrode and source electrode which were formed in the single side | surface of the said semiconductor chip, and the electrode of the said module substrate.

  A plurality of semiconductor chips are mounted on the module substrate surface, the bonding agent having irregularities on the surface is formed on the electrode of the module substrate, and when the bonding agent is cured, the bonding agent is applied to the electrodes of the plurality of semiconductor chips. You may make it harden by heating collectively the bonding agent of all the electrodes of the said corresponding module board | substrate.

  The present invention according to another aspect is a method of manufacturing a semiconductor module using the bonding method.

  According to the present invention, an electrode of a semiconductor chip and an electrode of a module substrate can be bonded using a paste-like bonding agent containing metal particles so that the bonding agent does not protrude laterally from the electrode.

It is a figure which shows an example of a semiconductor module. It is explanatory drawing which shows an example of the structure of the electrode of a semiconductor chip, and the electrode of a module substrate. It is explanatory drawing which shows the process of arrange | positioning a screen mask on a module board | substrate, and apply | coating a bonding agent on an electrode. It is explanatory drawing which shows the process of forming an unevenness | corrugation in the surface of the bonding agent of the electrode of a module substrate. It is explanatory drawing which shows the process of aligning the height of the convex part of the unevenness | corrugation of the surface of a bonding agent. It is explanatory drawing which shows the bonding | curing agent hardened | cured in the state with an unevenness | corrugation on the surface. It is explanatory drawing which shows the process of arrange | positioning a screen mask on a semiconductor chip, and apply | coating a bonding agent on an electrode. It is explanatory drawing which shows the bonding agent apply | coated on the electrode of a semiconductor chip. It is explanatory drawing which shows the process of making the electrode of a semiconductor chip and the electrode of a module substrate oppose. It is explanatory drawing which shows the process of match | combining the bonding agent of the electrode of a semiconductor chip, and the bonding agent of the electrode of a module substrate. It is explanatory drawing which shows the process of sintering the bonding agent between the electrode of a semiconductor chip and a module substrate. It is the photograph replaced with drawing which shows the circuit board after the screen printing of the gold paste to the electrode as one Example. It is a laser microscope 3D height mapping image which shows the uneven | corrugated state of a gold paste. It is a laser microscope 3D height mapping image which shows the state of the unevenness | corrugation after processus | protrusion height equalization.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an outline of a configuration of a semiconductor module 1 to which the bonding method according to the present embodiment is applied.

  The semiconductor module 1 has a so-called three-dimensional mounting structure such as a power module, and includes a plurality of semiconductor chips 10 and module substrates 11 and 12 bonded to respective electrode surfaces of these semiconductor chips 10. . The semiconductor chip 10 is a wide-gap semiconductor chip composed of a SiC or GaN chip body that can operate at a high temperature exceeding 200 ° C., for example.

  Each semiconductor chip 10 has, for example, a plurality of electrodes such as a gate electrode 20 and a source electrode 21 on one surface and a drain electrode 22 on the other surface.

  The gate electrode 20 and the source electrode 21 of the semiconductor chip 10 are bonded to the electrode 30 of the module substrate 11 by a bonding agent A described later. The drain electrode 22 of the semiconductor chip 10 is joined to the electrode 31 of the module substrate 12 by, for example, solder B.

  The gate electrode 20 and the source electrode 21 are made of metal such as Ni, Ti, Ag, Pt, Pd, and Al (Ni and Al in FIG. 2) formed on the surface of the SiC chip body as shown in FIG. It consists of a thin film and a thin Au film formed on the surface. The Au thin film has a thickness of about 0.01 μm to 10 μm, for example.

  The electrode 30 of the module substrate 11 includes, for example, a Cu film formed on the surface of a SiN substrate, a single-layer film of Ni-P and Ni-B formed on the surface, Ni-P or Ni-B and its It is composed of a thin film such as a two-layer film made of barrier metal (WN, Ta, TaN, Ti, TiN, Pd) and an Au thin film formed on the surface thereof. This Au thin film can also take the thickness arbitrarily set, for example from the range of 0.01 micrometer-10 micrometers.

  The bonding agent A is obtained by sintering a gold paste containing submicron gold fine particles having a particle diameter of 0.05 μm to 0.5 μm and made of the same material as the surfaces of the electrodes 20, 21, 30 to be bonded. The thickness of the bonding agent A is set to a predetermined target thickness arbitrarily selected from a range of about 1 μm to 100 μm, for example. The gold paste of the material of the bonding agent A has a high viscosity such that the gold content is as high as 90 wt% or more and self-leveling does not occur or self-leveling hardly occurs. For example, AuRoFUSE (registered trademark) manufactured by Tanaka Kikinzoku Kogyo is used as the gold paste.

  The bonding method according to the present embodiment is applied to, for example, bonding of the gate electrode 20 and the source electrode 21 of the semiconductor chip 10 and the electrode 30 of the module substrate 11 in the semiconductor module 1. Hereinafter, the joining method of the said part is demonstrated.

  First, in the screen printing machine, the surface of the module substrate 11 is covered with a mesh screen mask 50 as shown in FIG. Then, the paste-like bonding agent A is poured onto the electrode 30 through the screen mask 50 by the squeegee 51, and the paste-like bonding agent A is printed and applied onto the electrode 30. At this time, the bonding agent A is collectively applied to all the electrodes 30 on the module substrate 11 on which the semiconductor chip 10 is mounted.

  Next, the screen mask 50 is detached upward from the surface of the module substrate 11 as shown in FIG. At this time, a part of the bonding agent A is pulled upward together with the mesh lines of the screen mask 50, and irregularities due to the mesh of the screen mask 50 are formed on the surface of the bonding agent A. A convex portion 60 is formed at a portion corresponding to the intersecting portion of the mesh line on the surface of the bonding agent A, and a portion corresponding to the hole portion of the mesh line is a concave portion 61. At this time, since the viscosity of the bonding agent A is high, a part of the bonding agent A is pulled well by the screen mask 50 to form sufficient unevenness. Moreover, the height of the convex part 60 becomes larger than the final target thickness D of the bonding agent A.

  Next, as shown in FIG. 5, the plate-like member 70 is pressed against the uneven protrusion 60 on the surface of the bonding agent A. The plate-like member 70 is made of, for example, square glass, fluororesin, or polyethylene, and has a lower wettability with respect to the bonding agent A than the screen mask 50. The height of the plate-like member 70 when pressed (the gap between the plate-like member 70 and the electrode 30) is such that the height of the convex portion 60 from the electrode surface becomes the final target thickness D of the bonding agent A. Is set. Thus, the heights of the convex portions 60 are aligned.

  Next, in a state where the plate-like member 70 is pressed against the convex portion 60, the bonding agent A is heated and pre-sintered at a predetermined temperature (for example, about 2 minutes, about 200 ° C.) for a predetermined time. Thereby, as shown in FIG. 6, the bonding agent A is cured in a state where the surface is uneven. In this heating step, the entire module substrate 11 is heated, and all the bonding agents A of the electrodes 30 of the module substrate 11 are heated at once and cured. Moreover, the thin film of Au on the surface of the electrode 30 of the module substrate 11 and the bonding agent A are also bonded by this heating.

  Here, as an example, a gold paste was actually used as the bonding agent A, and this was screen-printed on the gate electrode and the source electrode of an SiN-AMC (Active Material brazed Copper) circuit board. The result is shown in FIG. It can be seen that the mesh marks of the screen mask remain on the paste surface and periodic irregularities appear. The screen mask used has an emulsion thickness of 10 μm, a mesh wire diameter of 30 μm, a cocoon thickness of 60 μm, and a mesh interval of 100 μm. During printing, the paste passes through the opening of the mesh and wraps under the mesh, whereby the paste is printed and applied to the entire mask pattern opening. Since the paste is in contact with the mesh at this point, the paste is dragged to the mesh by the surface tension during the plate separation process for separating the mask, and a mesh mark is formed. When the gold paste on the circuit immediately after coating was measured using a non-contact three-dimensional measuring apparatus, the thickness was 30 μm on average and 25 μm at the thin part. The interval between the irregularities was 100 μm. Since the unevenness interval and the mesh interval are the same, it can be determined that the unevenness is caused by the mesh. Since the unevenness is formed by being dragged by the mesh, there is a variation in the apex height of the protrusion, that is, the height of the convex portion. The maximum height of the measured protrusion was 85 μm, the minimum height of the protrusion was 60 μm, and there was a height variation of 25 μm. FIG. 13 shows a 3D height mapping image of a laser microscope with respect to the surface shape when the printed gold paste is temporarily sintered without aligning the heights of the protrusions. Even after the preliminary sintering, it is possible to confirm the irregularities and the protrusions at the mesh intersections that match the pitch of the mesh. The highest protrusion in the field of view of the figure was 36.8 μm (58.8 μm from the electrode surface), the lowest protrusion was 28.1 μm (50.1 μm from the electrode surface), and the difference was 8.7 μm. Subsequently, glass was pressed against the paste irregularities, and the height of the protrusions was made uniform, and then preliminary sintering was performed. Since the height of the protrusion immediately after application of the gold paste was in the range of 60 to 85 μm, the gap between the substrate and the glass was set to 60 μm, the apex portion of the protrusion was crushed, and preliminary sintering was performed at 200 ° C. for 2 minutes. . FIG. 14 shows a 3D height mapping image by a laser microscope of a mesh mark whose convex portions are leveled by this protrusion suppression process. It can be seen that the protrusions are leveled to a height of 22.8 μm (44.8 μm from the electrode surface). The height variation of each vertex was about ± 0.1 μm. This process also leads to suppression of mounting height variation at the time of chip bonding in the double-sided mounting module or height variation from the gold pace that causes inclination. It goes without saying that the above data is only one example.

  On the other hand, in the screen printing machine, the surfaces of the electrodes 20 and 21 of the semiconductor chip 10 are covered with a mesh screen mask 50 as shown in FIG. 7 (note that only one electrode is shown in FIG. 7). Then, the paste-like bonding agent A is poured onto the electrodes 20 and 21 through the screen mask 50 by the squeegee 51, and the bonding agent A is printed and applied onto the electrodes 20 and 21. The application amount of the bonding agent A at this time is set to be equal to the total volume of the concave portions 61 of the bonding agent A cured on the module substrate 11 side. Thereafter, the screen mask 50 is detached from the semiconductor chip 10. In this way, as shown in FIG. 8, the uncured paste-like bonding agent A is applied on the electrode 20 (21) of the semiconductor chip 10.

  Next, in the heating apparatus, as shown in FIG. 9, the module substrate 11 is held by the lower head 80, the semiconductor chip 10 is held by the upper head 81, the electrode 30 of the module substrate 11, the electrode 20 of the semiconductor chip 10, 21 are aligned so as to face each other. Thereafter, as shown in FIG. 10, the paste-like bonding agent A of the semiconductor chip 10 is pressed against the bonding agent A cured on the electrode 30 of the module substrate 11. At this time, since the bonding agent A on the module substrate 11 side is cured, the paste-like bonding agent A on the semiconductor chip 10 side enters the recess 61. Since the amount of the paste-like bonding agent A on the semiconductor chip 10 side is equivalent to the total volume of the recess 61, the bonding agent A on the semiconductor chip 10 side fills the recess 61, and the entire bonding agent A is 1 μm to 100 μm. A predetermined target thickness D is obtained.

  Thereafter, the bonding agent A is heated and pre-sintered at a predetermined temperature (for example, about 200 ° C.) that is a first temperature for a predetermined time (for example, 2 minutes), and then for a predetermined time (for example, 10 minutes) for the second time. Sintering is performed at a predetermined temperature (for example, 250 ° C.), and the bonding agent A on the semiconductor chip 10 side and the bonding agent A on the module substrate 11 side are metal bonded as shown in FIG. Moreover, the thin film of Au on the surfaces of the electrodes 20 and 21 of the semiconductor chip 10 and the bonding agent A are also bonded by these heating. Thus, the electrodes 20 and 21 of the semiconductor chip 10 and the electrode 30 of the module substrate 11 are joined. Thereafter, the semiconductor chip 10 and the module substrate 11 are naturally cooled.

  The drain electrode 22 of the semiconductor chip 10 and the electrode 31 of the module substrate 12 are joined by die bonding using, for example, solder B.

  According to the present embodiment, the paste-like bonding agent A containing gold fine particles is applied to the electrodes 20 and 21 of the semiconductor chip 10 and the electrode 30 of the module substrate 11, respectively, and the bonding agent A of the electrode 30 on the module substrate 11 side is applied. The surface of the module substrate 11 is hardened, and the bonding agent A on the module substrate 11 side is combined with the paste-like uncured bonding agent A on the semiconductor chip 10 side. The bonding agent A serves as a mold, and the uncured bonding agent A of the semiconductor chip 10 enters the concave and convex portions of the bonding agent A. As a result, the electrodes can be bonded to each other so that the bonding agent A does not protrude to the side of the electrodes even if a paste-like bonding agent A containing metal particles is used instead of the solder. Since the bonding agent A can be used in this way, a plurality of types of solder having different melting points are not required, and three-dimensional mounting with a plurality of bonding steps can be appropriately performed. Furthermore, three-dimensional mounting of a semiconductor chip that can be operated at high temperature can be realized.

  Further, the step of applying the bonding agent A to the electrode 30 of the module substrate 11 is performed using screen printing, and the screen mask 50 is separated from the electrode 30, whereby irregularities can be easily and appropriately formed on the surface of the bonding agent A. . In particular, according to screen printing, regular and stable irregularities can be formed. Therefore, it is easy to determine the amount of the bonding agent A applied to the semiconductor chip 10 side, and the protrusion of the bonding agent A can be more reliably suppressed.

  In the present embodiment, before the step of curing the bonding agent A, the plate-like member 70 is pressed against the surface of the bonding agent A, and the height of the convex portions 60 on the surface is made uniform, so that the volume of the concave portions 61 is made more constant. Thus, the amount of the coating agent A on the semiconductor chip 10 side can be easily determined. Therefore, the protrusion of the bonding agent A can be more reliably suppressed. In addition, the thickness of the entire bonding agent A when the bonding agent A on the module substrate 11 side and the bonding agent A on the semiconductor chip 10 side are combined can be stabilized.

  Since the height of the convex portion 60 aligned by the plate-like member 70 is set to the target thickness D of the bonding agent A that is finally disposed between the electrodes, the bonding agent A on the semiconductor chip 10 side is used in a later step. The final thickness of the bonding agent A is adjusted to the target thickness D by pressing the bonding agent A on the module substrate 11 side and putting the bonding agent A on the semiconductor chip 10 side into the recess 61 of the bonding agent A on the module substrate 11 side. It becomes easy to do.

  In the present embodiment, the gate electrode 20 and the source electrode 21 on one side of the semiconductor chip 10 and the electrode 30 of the module substrate 11 are bonded using the above bonding method. Therefore, even the gate electrode 20 and the source electrode 21 with a narrow interval of about several tens to several hundreds of μm can be joined to the module substrate 11 without being short-circuited.

  By the way, in joining the bonding agent A of a gold paste containing submicron gold fine particles and the Cu / Ni-P / Au plating surface of a general electrode of the module substrate 11, the electrode is kept at about 200 ° C. in the atmosphere. If there is a heat history such as heating, bonding is not sufficiently performed. Therefore, when a plurality of semiconductor chips 10 are mounted on the surface of one module substrate 11, each module chip 11 is heated to a high temperature and bonded to each semiconductor chip 10 by a flip chip each time. The chip 10 can be bonded, but the second and subsequent semiconductor chips 10 have a thermal history on the module substrate 11 side, so that bonding becomes difficult. Experiments have shown that this problem can be avoided by increasing the thickness of the Au film on the module substrate electrode to several μm. However, in this method, it is necessary to apply a thick gold plating to the entire electrode surface of the module substrate, which causes a cost problem.

  According to the present embodiment, since all the bonding agents A of the electrodes 30 of the module substrate 11 corresponding to the electrodes 20 and 21 of the plurality of semiconductor chips 10 are collectively heated and cured, a module having a thermal history The bonding agent A of the gold paste is not bonded to the electrode 30 of the substrate 11, and all the bonding agents A and the module substrate 11 can be appropriately bonded. Further, since it is not necessary to form a thick gold plating on the electrode surface, the cost problem can be solved. Furthermore, since the portion to which the gold paste is applied is only the joint portion, the cost can be reduced in this respect as compared with the case where thick gold plating is formed on the entire electrode surface.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the idea described in the claims, and these naturally belong to the technical scope of the present invention. It is understood.

  For example, in the above embodiment, the surface of the bonding agent A is formed with irregularities by the screen-printed mesh screen mask 50. However, other methods, for example, using a stencil mask or the like and using a squeegee or the like. Then, the unevenness may be formed by applying the adhesive A and releasing the mask from the surface. Alternatively, after forming the bonding material A having no unevenness, a columnar structure such as a bump may be formed separately to form a spacer (unevenness).

  The bonding agent A is a gold paste containing submicron gold fine particles, but may be a paste containing other metal particles such as silver. The same material as the electrode surface is selected for the metal particles at this time. Further, the unevenness was formed on the bonding agent A of the electrode on the module substrate 11 side and cured, but the unevenness was formed on the bonding agent A of the electrode on the semiconductor chip 10 side and cured to bond the bonding on the semiconductor chip 10 side. The uncured bonding agent A on the module substrate 11 side may be combined with the agent A.

  The present invention can also be applied to a semiconductor module having a configuration other than the configuration of the semiconductor chip 10 and the module substrate 11 of the present embodiment. In addition, in the semiconductor module in which the module substrate is bonded to both surfaces of the semiconductor chip, the bonding method according to the present embodiment is applied not only to the bonding of the electrode of one module substrate and the electrode of the semiconductor chip but also to the bonding of both. May be. Further, the bonding method according to the present embodiment is a method of bonding a semiconductor chip having a plurality of electrodes on one side and a module substrate. However, when bonding a semiconductor chip having one electrode on one side and a module substrate. You may apply.

  In the above embodiment, the plate-like member 70 is pressed against the surface of the bonding agent A, and the height of the convex portions 60 on the surface is made uniform. However, this step is not necessary, and the surface of the bonding agent A is made uneven. After that, the bonding agent A may be cured immediately.

DESCRIPTION OF SYMBOLS 1 Semiconductor module 10 Semiconductor chip 11 Module board | substrate 20 Gate electrode 21 Source electrode 22 Drain electrode 30 Electrode 50 Screen mask 60 Convex part 61 Concave part 70 Plate-shaped member A Bonding agent

Claims (8)

In a semiconductor module in which a module substrate is bonded to both surfaces of a semiconductor chip, a method of bonding an electrode of at least one module substrate and an electrode of a semiconductor chip,
Applying a paste-like bonding agent containing metal particles to each of the electrode of the semiconductor chip and the electrode of the module substrate;
Forming irregularities on the surface of the bonding agent of one of the semiconductor chip and the module substrate; and
Curing the bonding agent in a state where the surface has irregularities;
The step of combining the bonding agent cured in a state where the surface of the one electrode of the semiconductor chip and the module substrate is uneven and the uncured bonding agent of the other electrode;
Sintering the combined metal particles of the bonding agent. The step of applying the bonding agent is performed using screen printing in which a screen mask is arranged on the electrode, and the paste adhesive is applied to the electrode through the screen mask.
The bonding method according to claim 1, wherein the step of forming irregularities on the surface of the bonding agent is performed by separating the screen mask from the electrode.   The method further comprises the step of pressing a plate-like member against the surface of the bonding agent and aligning the heights of the protrusions of the unevenness before the step of curing the bonding agent with the surface having unevenness. Or the joining method of 2.   The bonding method according to claim 3, wherein the height of the convex portion aligned by the plate-like member is set to a target thickness of a bonding agent that is finally disposed between the electrodes. The bonding method according to claim 1, wherein the paste-like bonding agent is a gold paste having gold fine particles having a particle size of 0.05 μm or more and 0.5 μm or less .   The bonding method according to claim 1, wherein a gate electrode and a source electrode formed on one surface of the semiconductor chip are bonded to an electrode of the module substrate. A plurality of semiconductor chips are mounted in the module substrate surface,
Forming the bonding agent having irregularities on the surface thereof on the electrode of the module substrate;
When curing the bonding agent, the bonding agent for all the electrodes of the module substrate corresponding to the electrodes of the plurality of semiconductor chips is collectively heated and cured. The joining method described.   The method to manufacture a semiconductor module using the joining method in any one of Claims 1-7.