JP7254216B2 - Semiconductor device manufacturing method - Google Patents

Description

The present disclosure relates to a method of manufacturing a semiconductor device.

2. Description of the Related Art Conventionally, in a power module, which is an example of a semiconductor device, it has been considered to use a sinterable metal bonding material containing fine metal particles as a bonding material to bond a semiconductor element to a substrate. As one method for supplying such a bonding material onto a substrate, a screen printing method using a metal mask having openings and a squeegee is known (see, for example, Japanese Patent Application Laid-Open No. 2016-190182). Japanese Unexamined Patent Application Publication No. 2016-190182 discloses that when a protrusion is formed on the applied bonding agent, a problem occurs such that a semiconductor element bonded by the bonding agent is damaged. In JP-A-2016-190182, in order to prevent the problem, a stepped portion is provided in the upper portion of the opening of the metal mask on the end side in the moving direction of the squeegee. Japanese Patent Application Laid-Open No. 2016-190182 states that excess bonding material can escape to the stepped portion when the bonding material is applied, so that formation of protrusions in the applied bonding material is suppressed.

JP 2016-190182 A

However, even with the above-described conventional method, the semiconductor element may be damaged when the semiconductor element is bonded to the bonding material.

Accordingly, an object of the present disclosure is to provide a method of manufacturing a semiconductor device capable of suppressing the occurrence of defects such as breakage of a semiconductor element when the semiconductor element is bonded to a bonding material.

A method of manufacturing a semiconductor device according to the present disclosure includes a step of preparing a substrate, a step of supplying a substrate, and a step of bonding. In the supplying step, a sinterable metal bonding material is supplied onto the surface of the substrate. In the bonding step, the semiconductor element is bonded to the substrate via the sinterable metal bonding material. In the supplying step, a metal mask having an opening is placed on the surface of the substrate, and the sinterable metal bonding material is supplied to the surface portion of the substrate exposed inside the opening using a squeegee. In the supplying step, in plan view, the surface portion of the substrate to which the sinterable metal bonding material is supplied and the contact area of the metal mask with which the squeegee contacts are arranged with a gap therebetween.

According to the above, it is possible to suppress the occurrence of a defect that the semiconductor element is damaged when the semiconductor element is bonded to the bonding material.

5 is a flow chart for explaining a method of manufacturing a semiconductor device according to Embodiment 1; 2 is a schematic cross-sectional view of a semiconductor device obtained by the method of manufacturing the semiconductor device shown in FIG. 1; FIG. 2 is a schematic plan view for explaining a method of manufacturing the semiconductor device shown in FIG. 1; FIG. FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. 3; 1. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the semiconductor device shown in FIG. 1. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the semiconductor device shown in FIG. 1. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the semiconductor device shown in FIG. 1. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the semiconductor device shown in FIG. 1. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the semiconductor device shown in FIG. 2 is a schematic diagram for explaining the effects of the method for manufacturing the semiconductor device shown in FIG. 1; FIG. 2 is a schematic diagram for explaining the effects of the method for manufacturing the semiconductor device shown in FIG. 1; FIG. FIG. 10 is a schematic diagram showing a squeegee used in the method of manufacturing a semiconductor device according to the second embodiment; FIG. 10 is a schematic diagram for explaining the method of manufacturing the semiconductor device according to the second embodiment; FIG. 10 is a schematic diagram for explaining the method of manufacturing the semiconductor device according to the second embodiment; FIG. 11 is a schematic plan view of a semiconductor device according to a third embodiment; FIG. 16 is a schematic cross-sectional view along the line segment XVI-XVI in FIG. 15; FIG. 11 is a schematic plan view for explaining a substrate of a semiconductor device according to a third embodiment; FIG. 12 is a schematic plan view showing a metal mask used in the method for manufacturing a semiconductor device according to the third embodiment; FIG. 19 is a schematic cross-sectional view taken along line segment XIX-XIX in FIG. 18; FIG. 19 is a schematic cross-sectional view taken along line XX-XX in FIG. 18; FIG. 11 is a schematic diagram for explaining a method of manufacturing a semiconductor device according to a third embodiment; FIG. 11 is a schematic diagram for explaining a method of manufacturing a semiconductor device according to a third embodiment; FIG. 11 is a schematic diagram for explaining a method of manufacturing a semiconductor device according to a third embodiment; 4 is a graph showing the relationship between the number and size of aggregates for samples of Examples and Comparative Examples.

Embodiments of the present disclosure will be described below. In addition, the same reference numerals are given to the same configurations, and the description thereof will not be repeated.

Embodiment 1.
<Method for manufacturing a semiconductor device>
FIG. 1 is a flow chart for explaining the method of manufacturing a semiconductor device according to the first embodiment. FIG. 2 is a schematic cross-sectional view of a semiconductor device obtained by the method of manufacturing the semiconductor device shown in FIG. FIG. 3 is a schematic plan view for explaining a method of manufacturing the semiconductor device shown in FIG. FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a schematic cross-sectional view for explaining a method of manufacturing the semiconductor device shown in FIG. 6 to 9 are schematic cross-sectional views for explaining the method of manufacturing the semiconductor device shown in FIG. A method for manufacturing a semiconductor device according to this embodiment will be described with reference to FIGS.

In the method of manufacturing the semiconductor device shown in FIG. 1, the semiconductor device 4 as shown in FIG. 2 is obtained. A semiconductor device 4 shown in FIG. 2 includes a substrate 1 and a semiconductor element 3 connected to the substrate 1 via a bonding layer 2 . The bonding layer 2 is a member formed by drying a sinterable metal bonding material 22 (see FIG. 6) and then heating it while applying pressure, as will be described later. The bonding layer 2 fixes the semiconductor element 3 to the substrate 1 .

1 uses metal mask 6 and squeegee 9 as shown in FIGS. As shown in FIGS. 3 and 4, the metal mask 6 includes a first surface 6a with which the squeegee 9 contacts and a second surface 6b. The second surface 6b is located on the side opposite to the first surface 6a. The second surface 6 b faces the front surface 1 a of the substrate 1 . An opening 7 is formed in the metal mask 6 . The opening 7 is formed to reach from the first surface 6a to the second surface 6b. A first surface 6 a of the metal mask 6 is formed with a recess 8 surrounding the opening 7 and communicating with the opening 7 .

When metal mask 6 is placed on surface 1 a of substrate 1 , surface portion 1 aa of substrate 1 is exposed inside opening 7 . As will be described later, a sinterable metal bonding material 22 is supplied to the surface portion 1aa. As shown in FIG. 3, the total width W2 of the recess 8 and the opening 7 is smaller than the length W3 of the squeegee 9. As shown in FIG. A groove 10 is formed around the opening 7 in the second surface 6b of the metal mask 6, as shown in FIG.

Using such metal mask 6 and squeegee 9, the method of manufacturing the semiconductor device shown in FIG. 1 is carried out. A specific description will be given below. Note that FIG. 6, which will be described later, illustrates a case in which only one opening 7 is formed as the metal mask 6 in order to simplify the explanation.

As shown in FIG. 1, in the method of manufacturing a semiconductor device according to the present embodiment, first, a preparatory step (S1) is performed. In this step (S1), as shown in FIG. 5, a substrate 1 constituting a semiconductor device is prepared. Substrate 1 is, for example, a metal substrate containing copper (Cu) or aluminum (Al), or an insulating substrate made of aluminum oxide (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), or the like. A ceramic insulating substrate obtained by laminating and fixing a conductive layer made of a metal such as copper or aluminum can be used as the ceramic substrate. The conductor layer constituting the ceramic insulating substrate described above may be a metal layer consisting of a single layer, or may be a composite layer in which a conductive coating layer is formed on the surface of a conductor layer serving as a base. may Copper, aluminum, or the like, for example, can be used as the material of the conductor layer serving as the base. Moreover, noble metals such as silver (Ag) and gold (Au) can be used as the material of the coating layer.

Here, for example, substrate 1 may be a ceramic substrate made of silicon nitride, to which copper plates as conductor layers are connected on both sides. The copper plate may be fixed to the ceramic substrate with a brazing material as a bonding material. As the brazing material, an Ag--Cu--Ti brazing material containing silver and copper as main components and adding titanium (Ti) as an activator may be used. The thickness of the ceramic substrate described above may be, for example, 0.3 mm. The thickness of the copper plate may be 0.4 mm, for example.

Next, a bonding material supply step (S2) is performed. In this step (S2), as shown in FIG. 6, a sinterable metal bonding material 22 is supplied onto the surface 1a of the substrate 1 using a screen printing method. Specifically, in step ( S<b>2 ), a metal mask 6 having openings 7 is arranged on surface 1 a of substrate 1 . Metal mask 6 has a thickness T1. A sinterable metal bonding material 22 is placed inside the opening 7 .

In addition, in bonding using the above-described sinterable metal bonding material 22 (sinterable metal bonding), the metal fine particles contained in the sinterable metal bonding material 22 have a melting point higher than the melting point of the metal that constitutes the metal fine particles. A phenomenon of sintering at a low temperature is utilized to achieve metallic bonding between the semiconductor element 3 as a member to be joined and the substrate 1 . In particular, fine metal particles that have been miniaturized to nanometer-level sizes exhibit the characteristic that sintering reactions occur even at room temperature. However, in the sinterable metal bonding material 22 that has undergone a sintering reaction once, the size of the metal fine particles increases, resulting in problems such as reduced reactivity. Therefore, the sinterable metal bonding material 22 contains fine metal particles and an organic solvent component for dispersing the fine metal particles. A protective film is formed.

After that, the squeegee 9 is moved so as to pass over the opening 7 while being in contact with the first surface 6 a of the metal mask 6 . At this time, as shown in FIG. longer than the distance L2 moved in the state of Further, the distance L2 is longer than the total length L1 of the openings 7 in the movement direction of the squeegee 9. As shown in FIG.

As a result, the sinterable metal bonding material 22 is supplied to the surface portion 1aa of the substrate 1 exposed inside the opening 7 . In the step (S2), since the recesses 8 are formed in the metal mask 6, as can be seen from FIGS. and a contact region 6aa of the metal mask 6 with which the squeegee 9 contacts.

After that, the metal mask 6 is removed from the surface 1 a of the substrate 1 . In this manner, a sinterable metal bonding material 22 having a thickness T1 can be supplied onto the surface 1a of the substrate 1 as shown in FIG. The thickness T1 of the sinterable metal bonding material 22 can be, for example, 30 μm or more and 200 μm or less. Further, by using the metal mask 6 as described above, the opening end of the opening 7 of the metal mask 6 and the squeegee 9 do not come into contact with each other. It is possible to prevent the occurrence of an event in which a shear stress is applied by being pinched at the contact portion with 6 .

Next, a drying step (S3) is performed. In this step (S3), the sinterable metal bonding material 22 supplied to the surface portion 1aa of the substrate 1 is dried by heating. As a result, as shown in FIG. 8, the dried sinterable metal bonding material 22a in which the organic component has volatilized to some extent is arranged on the surface 1a of the substrate 1. As shown in FIG. As an example of the process conditions of the step (S3), for example, the drying temperature can be 80° C. or more and 200° C. or less, and the drying time can be 1 minute or more and 60 minutes or less.

Next, a temporary fixing step (S4) is performed. In this step (S4), as shown in FIG. 9, the semiconductor element 3 is mounted on the dried sinterable metal bonding material 22a. As the semiconductor element 3, for example, a semiconductor element 3 using silicon (Si) can be used. A metallized back surface electrode is formed on the back surface of the semiconductor element 3 that is in contact with the dried sinterable metal bonding material 22a.

Then, the semiconductor element 3 is heated while being pressed against the substrate 1 side. The heating time at this time is shorter than the heating time in the bonding step (S5) described later. Moreover, the pressure for pressing the semiconductor element 3 at this time is also smaller than the pressure in the bonding step (S5) described later. The process conditions of step (S4) may be, for example, a heating temperature of 25° C. or higher and 200° C. or lower, a pressing pressure of 0.01 MPa or higher and 5 MPa or lower, and a pressing time of 0 minute or longer and 1 minute or shorter.

Although silicon (Si) may be used as a material for forming the semiconductor element 3, silicon carbide (SiC), gallium nitride (GaN), or diamond, which has a wider bandgap than silicon, is a so-called wideband material. Gap semiconductor materials may be applied. The device type of the semiconductor element 3 is not particularly limited, but switching elements such as IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (metal-oxide-semiconductor field-effect transistors) and rectifying elements such as diodes are semiconductor elements. 3 can be used. The planar shape of the semiconductor element 3 can be, for example, a rectangle having a side of about 5 mm or more and 20 mm or less. For example, when silicon (Si) is used as the material of the semiconductor element 3 that functions as a switching element or a rectifying element, the cost is lower than that of a semiconductor element using silicon carbide (SiC), for which the application of sinterable metal bonding is progressing. Since it is costly, it is possible to reduce the price of the power module to which the semiconductor device according to the present embodiment is applied. In addition, since bonding using the sinterable metal bonding material 22 (sinterable metal bonding) has higher heat dissipation than conventional solder bonding, the semiconductor device 4 can operate at high temperatures. However, silicon (Si) has lower bending strength and hardness than silicon carbide (SiC). Therefore, it is necessary to reduce the pressure applied to the semiconductor element 3 when joining the sinterable metal rather than silicon carbide (SiC), and achieve the joining while preventing damage to the semiconductor element 3 . In the above-described embodiments, for example, silicon (Si) may be used as the material of the semiconductor element 3 . In this case, the size of the semiconductor element 3 can be 15 mm long×15 mm wide, and the thickness can be 0.15 mm.

Next, a bonding step (S5) is performed. In this step (S5), while pressing the semiconductor element 3 toward the substrate 1 with a pressure higher than that in the step (S4), the dried sinterable metal bonding material 22a is heated to form the bonding layer 2. (See FIG. 2). That is, in the step (S5), the semiconductor element 3 is bonded to the substrate 1 via the dried sinterable metal bonding material 22a. The heating temperature in step (S5) may be higher than the heating temperature in step (S4). Moreover, the heating temperature in step (S5) is lower than the melting point of the metal that constitutes the fine metal particles contained in the sinterable metal bonding material 22 . The process conditions of step (S5) may be, for example, a heating temperature of 250° C. or higher and 350° C. or lower, a pressing pressure of 0.1 MPa or higher and 50 MPa or lower, and a pressing time of 1 minute or longer and 60 minutes or shorter.

In the bonding layer 2 (see FIG. 2) obtained by heating the sinterable metal bonding material 22a by such pressurization and heat treatment, the fine metal particles are diffusion-bonded. Diffusion bonding is performed between the back electrode of the semiconductor element 3 and the bonding layer 2 . Furthermore, the surface 1a of the substrate 1 and the bonding layer 2 are also diffusion-bonded. As a result, the melting point of the bonding layer 2 becomes the melting point of the metal forming the bonding layer 2 . As a result, in the obtained semiconductor device 4, the heat resistance temperature can be made higher than the heating temperature in the step (S5). Thus, the semiconductor device 4 shown in FIG. 2 can be obtained.

After that, a post-processing step (S6) is performed. In this step (S6), lead electrodes are connected to the semiconductor element 3, a frame (not shown) is connected to the semiconductor device 4 using an adhesive, for example, and the semiconductor element 3 is embedded in the frame. Perform necessary steps such as placement of sealing resin. Thus, a semiconductor module can be obtained.

Incidentally, when connecting the lead electrodes (not shown) onto the semiconductor element 3 by soldering, the bonding of the semiconductor element 3 with the sinterable metal bonding material 22 has already been completed. Therefore, an adverse effect such as remelting of the sinterable metal joining material 22 does not occur due to a temperature rise of about 300° C. during soldering.

Further, as the sealing resin described above, a resin obtained by embedding the semiconductor element 3 and the like with a gel resin and then curing the gel resin may be used. Alternatively, the periphery of the semiconductor element 3 may be resin-sealed by another method such as sealing by silicone potting, molding, or the like. Alternatively, resin sealing may not be performed.

Here, bonding using the sinterable metal bonding material 22 (sinterable metal bonding) used in the above-described method of manufacturing a semiconductor device will be described in more detail. Sinterable metal bonding includes non-pressure sintering bonding in which the sinterable metal bonding material 22 is bonded only by heating without applying pressure, and pressure sintering in which the sinterable metal bonding material is heated while being pressed and bonded. It is roughly divided into joining and joining. This embodiment will be described using pressure sintering bonding.

The sinterable metal bonding material 22 contains nanometer-level fine metal particles as an aggregate. Nanometer-level fine metal particles have a very large surface area relative to their volume, and a large amount of surface energy. Therefore, the reactivity of the metal microparticles described above is high. Therefore, in bonding using the sinterable metal bonding material 22, the metal bonding between the metal fine particles progresses by diffusion at a temperature lower than the melting point of the metal constituting the metal fine particles in the bulk material state as described above. using the phenomenon.

The material that constitutes the fine metal particles that serve as the aggregate may be a single metal classified as a noble metal such as gold (Au), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), or the like. Alternatively, Ag--Pd alloy, Au--Si alloy, Au--Ge alloy, Au--Cu alloy, etc. may be used as the material. Gold, silver, copper, and the like, which are exemplified as materials for forming the metal fine particles, have higher thermal conductivity than solder. Therefore, the thickness of the bonding layer 2 made of the sinterable metal bonding material 22 can be made thinner than when solder is used, and high heat radiation performance can be achieved.

Due to its high reactivity, fine metal particles are sintered, i.e., diffusion-bonded, by simply contacting each other even at room temperature. Therefore, in the sinterable metal bonding material 22, the metal microparticles are covered with an organic protective film in order to prevent the metal microparticles from aggregating and advancing the sintering reaction. Furthermore, in order to make the plurality of metal fine particles independent, the plurality of metal fine particles are dispersed and held by an organic dispersing material. That is, the sinterable metal bonding material 22 is a paste obtained by dispersing fine metal particles as an aggregate in an organic component. At the time of bonding, organic components such as the organic protective film and the organic dispersing material volatilize, leaving only the metal material. In the above-described embodiment, for example, silver (Ag) particles having a nanometer level size may be used as the fine metal particles.

Methods for supplying the paste-like sinterable metal bonding material 22 onto the substrate 1 include a screen printing method in which the sinterable metal bonding material 22 is supplied using the metal mask 6 and the squeegee 9 as described above; A dispense supply method of supplying the sinterable metal bonding material 22 with air can be mentioned. In general, when bonding the semiconductor element 3 and the substrate 1, the thickness of the bonding layer 2 should be uniform and the entire surface of the semiconductor element 3 should be bonded to the sinterable metal bonding material 22. is preferred. For this reason, it is necessary to supply the sinterable metal bonding material 22 evenly on the surface 1a of the substrate 1 .

In the embodiment described above, the sinterable metal bonding material 22 is supplied onto the substrate 1 using the screen printing method. In the screen printing method, the sinterable metal bonding material 22 can be supplied flat on the substrate 1 in the same shape as the final bonding. Therefore, it is not necessary to crush the sinterable metal bonding material 22 supplied onto the substrate 1 with the semiconductor element 3 . Therefore, before mounting the semiconductor element 3 on the sinterable metal bonding material 22, the step (S3) of preliminarily volatilizing the solvent by heating can be performed. As a result, a semiconductor element 3 having a large size exceeding, for example, 10 mm long by 10 mm wide can be bonded to the substrate 1 without causing problems such as voids and defective bonding.

A metal mask 6 shown in FIG. 4 or 6 has a recess 8 which is a thin region around an opening 7 . The thickness of the metal mask 6 in the region where the concave portion 8 is formed may be approximately 10% or more and 90% or less of the thickness T1 of the metal mask 6 (see FIG. 6). From a different point of view, the depth from the first surface 6 a of the metal mask to the bottom of the recess 8 may be 10% or more and 90% or less of the thickness T1 of the metal mask 6 . By doing so, the effect of the present embodiment can be obtained.

In this embodiment, a metal mask 6 having a thickness T1 of 150 μm is used. The thickness of the region in which the concave portion 8 was formed was 110 μm, that is, the depth of the concave portion 8 was 40 μm. Examples of processing methods for the metal mask 6 forming the recesses 8 include a laser processing method and an etching method utilizing a chemical reaction using a chemical solution or the like. The metal mask 6 may be processed using any of the above-described methods or other methods. The metal mask 6 is generally made of stainless steel, for example, but any other material may be used depending on the type of the sinterable metal bonding material 22 . For example, nickel (Ni), aluminum (Al), copper (Cu), or the like may be used as the material of metal mask 6 . In this embodiment, stainless steel is used as the material of the metal mask 6, and the concave portions 8 are formed by laser processing.

The metal mask 6 having the openings 7 and the recesses 8 can be produced, for example, by stacking two metal masks formed with openings of different areas one on top of the other. A sheet of metal mask may be produced by processing a shaped member. The precision of the thickness of the metal mask 6 can be improved by processing one plate-shaped member by laser processing. As a result, the thickness of the sinterable metal bonding material 22 can be made more precise, and the manufacturing cost can be reduced by reducing the man-hours for manufacturing the metal mask 6 .

As shown in FIG. 3, the width W2 of the recess 8 is wider than the width W1 of the opening 7 of the metal mask 6 and narrower than the width W3 of the squeegee 9. As shown in FIG. The width W1 of the opening 7 of the metal mask 6 can be arbitrarily set depending on the product, and is not limited to a specific value. Further, the width W3 of the squeegee 9 should be larger than the width W1 of the opening 7 of the metal mask 6. FIG. A width W3 of the squeegee 9 can be, for example, 10 mm or more and 10000 mm or less. In this embodiment, the width W1 of the opening 7 of the metal mask 6 is 30 mm and the width W3 of the squeegee 9 is 50 mm, so the width W2 of the recess 8 is 40 mm. Note that the effect of the present embodiment can be obtained if the above relationship is satisfied even with values other than those described above. Here, the width W1 of the opening 7 means the width of the opening 7 when one opening 7 is formed inside one recess 8 as shown in FIG. Further, when a plurality of openings 7 are formed inside one recess 8 as shown in FIG. 3, the width W1 of the openings 7 means the width of the region where the plurality of openings 7 are formed.

Also, the length of the recess 8 in the movement direction of the squeegee 9 (the total length L3 of the recess 8 and the opening 7 in FIG. 3) should be longer than the distance L2, which is the driving range of the squeegee 9 . In this embodiment, the squeegee 9 is driven within a range of −60 mm to +60 mm from the center C of the region of the metal mask 6 where the openings 7 are formed in the direction indicated by the arrow 31 , which is the moving direction of the squeegee 9 . That is, the distance L2 was set to 120 mm. Therefore, the recesses 8 were formed in the range of -100 mm to +100 mm in the direction indicated by the arrow 31 from the center C of the region of the metal mask 6 where the openings 7 were formed. From a different point of view, the length L3 was set to 200 mm.

As shown in FIG. 4, on the second surface 6b of the metal mask 6, the groove 10 is formed around the opening 7 by half-etching as described above. The groove 10 serves to prevent the sinterable metal bonding material 22 from bleeding between the metal mask 6 and the substrate 1 during screen printing of the sinterable metal bonding material 22 .

The squeegee 9 is made of a metal plate such as stainless steel or aluminum (Al), or a metal plate made of stainless steel or the like with a plating layer of nickel (Ni) formed on the surface thereof, or a resin such as urethane rubber or polyester. A different plate material may be used. The material of the squeegee 9 can be arbitrarily selected according to the material of the sinterable metal bonding material 22 and the supply area of the sinterable metal bonding material 22 . Also, the thickness, width, hardness, etc. of the squeegee 9 can be arbitrarily set. In this embodiment, the squeegee 9 is, for example, a plate made of polyester resin and having a thickness of 0.2 mm. Note that squeegees 9 of other materials and sizes may be used.

<Effect>
A method of manufacturing a semiconductor device according to the present disclosure includes a step of preparing a substrate (S1), a step of supplying (S2), and a step of bonding (S5). In the supplying step (S2), the sinterable metal bonding material 22 is supplied onto the surface 1a of the substrate 1. As shown in FIG. In the bonding step (S5), the semiconductor element 3 is bonded to the substrate 1 via the sinterable metal bonding material 22a. In the supply step (S2), a metal mask 6 having an opening 7 is placed on the surface 1a of the substrate 1, and a squeegee 9 is used to sinter the surface portion 1aa of the substrate 1 exposed inside the opening 7. A flexible metal bonding material 22 is supplied. In the supplying step (S2), the surface portion 1aa of the substrate 1 to which the sinterable metal bonding material 22 is supplied and the contact area 6aa of the metal mask 6 with which the squeegee 9 contacts are arranged with a gap in plan view. It is

In this way, since the opening end of the opening 7 and the squeegee 9 do not come into contact with each other, the sinterable metal bonding material 22 is sandwiched between the opening end of the opening 7 and the squeegee 9, and the shear stress is reduced. It is possible to suppress the occurrence of problems such as the formation of aggregates. As a result, it is possible to suppress the occurrence of the problem that the semiconductor element 3 forming the semiconductor device 4 is damaged due to the presence of the aggregates, and as a result, it is possible to improve the reliability of the semiconductor device.

In the method of manufacturing a semiconductor device described above, the metal mask 6 includes a first surface 6a with which the squeegee 9 contacts, and a second surface 6b. The second surface 6b is positioned opposite to the first surface 6a and faces the front surface 1a of the substrate 1 . The opening 7 is formed to reach from the first surface 6a to the second surface 6b. A first surface 6 a of the metal mask 6 is formed with a recess 8 surrounding the opening 7 and communicating with the opening 7 .

In this case, by forming the concave portion 8, the surface portion 1aa of the substrate 1 where the sinterable metal bonding material 22 is arranged and the contact region 6aa of the metal mask 6 with which the squeegee 9 contacts can be easily arranged with a gap therebetween. be able to. Furthermore, when the sinterable metal bonding material 22 is arranged in the recessed portion 8 connected to the opening 7 in the metal mask 6, the thickness of the sinterable metal bonding material 22 located in the recessed portion 8 is equal to the depth of the recessed portion 8. It can be made thicker to some extent depending on the Therefore, it is possible to suppress the occurrence of the problem that the organic component completely volatilizes from the sinterable metal bonding material 22 positioned in the recess 8 and the sinterable metal bonding material 22 solidifies.

Hereinafter, the effects of the method for manufacturing a semiconductor device according to this embodiment will be described more specifically. In general screen printing, the positional relationship between the metal mask 6 and the squeegee 9 greatly affects the supply amount of the sinterable metal bonding material 22 and the shape after supply. When the metal mask 6 and the squeegee 9 are not substantially in contact with each other, the sinterable metal bonding material 22 cannot be supplied evenly due to the warping of the substrate 1 and the inclination of the squeegee 9. supply is unstable. On the other hand, when the metal mask 6 and the squeegee 9 are in strong contact with each other, the sinterable metal bonding material 22 can be supplied evenly and stably. However, a large shear stress is locally applied to the sinterable metal bonding material 22 at the location where the edge of the squeegee 9 in the driving direction in the opening 7 of the metal mask 6 contacts the squeegee 9 . As a result, the organic protective film covering the metal fine particles is destroyed so that the metal fine particles are not sintered in the sinterable metal bonding material 22, and the metal fine particles with the organic protective film destroyed react with each other. , aggregates 11 of fine metal particles are formed as shown in FIG. 10 and 11 are schematic diagrams for explaining the effects of the method for manufacturing the semiconductor device shown in FIG.

FIG. 10 shows the case where the aggregate 11 exists in the sinterable metal bonding material 22a when the semiconductor element 3 is bonded. When the aggregates 11 are present in the sinterable metal bonding material 22, pressing the semiconductor element 3 as indicated by an arrow 32 during bonding of the semiconductor element 3 causes a region of the semiconductor element 3 in contact with the aggregates 11. stress is concentrated on As a result, as shown in FIG. 11, in the semiconductor element 3, a bending stress is generated starting from a portion in contact with the aggregate 11, and a crack 12 is generated.

Also, when the sinterable metal bonding material 22 on the metal mask 6 is poured into the opening 7 using the squeegee 9 , a small amount of the sinterable metal bonding material 22 may remain on the metal mask 6 . This is because even when the squeegee 9 and the metal mask 6 are brought into close contact with each other, a slight gap may occur between the squeegee 9 and the metal mask 6, and the sinterable metal bonding material 22 may remain in the gap. is. The remaining sinterable metal bonding material 22 is coated with a very thin film having a thickness of, for example, 1 μm or more and 10 μm or less. In the sinterable metal bonding material 22 in such a thinly applied state, organic components and the like contained therein are likely to volatilize. That is, after the sinterable metal bonding material 22 is supplied onto the substrate 1 using the squeegee 9, a part of the sinterable metal bonding material 22 thinly coated on the surface of the metal mask 6 can be used in a short time. Organic components volatilize. As a result, the part of the sinterable metal bonding material 22 solidifies from the paste state, and may become the core of the aggregate 11 .

To solve these problems, in the method of manufacturing a semiconductor device according to the present embodiment, recesses 8 are provided in metal mask 6 . As a result, the metal mask 6 and the squeegee 9 are brought into contact with each other outside the recess 8 with a force of, for example, 1 kgf or more and 30 kgf or less, so that the supply amount of the sinterable metal bonding material 22 can be stabilized. At the same time, the edge of the opening 7 of the metal mask 6 and the squeegee 9 are prevented from coming into contact with each other by the concave portion 8, thereby preventing the generation of the aggregate 11 of the fine metal particles. Furthermore, the sinterable metal bonding material 22 is applied to the recesses 8 in a thickness corresponding to the difference between the thickness T1 of the metal mask 6 and the thickness of the metal mask 6 at the portions where the recesses 8 are formed (that is, the depth of the recesses 8). ing. Therefore, volatilization of the organic component is suppressed in the sinterable metal bonding material 22 arranged in the recess 8, and solidification of the sinterable metal bonding material 22 can be suppressed.

That is, in general, in the screen printing method, the supply amount of the sinterable metal bonding material 22 changes depending on the positional relationship between the metal mask 6 and the squeegee 9 . When the metal mask 6 and the squeegee 9 are separated from each other, the position of the metal mask 6 changes due to warping of the substrate 1 or the like, so that the supply amount of the sinterable metal bonding material 22 varies greatly. On the other hand, when the metal mask 6 and the squeegee 9 are in contact with each other, the supply amount of the sinterable metal bonding material 22 is constant. , aggregates 11 increase. However, in the method of manufacturing a semiconductor device according to the present embodiment, while the metal mask 6 and the squeegee 9 are in contact with each other outside the recess 8, the edge of the opening 7 of the metal mask 6 and the squeegee 9 are not in contact with each other. Screen printing of the adhesive metal bonding material 22 is possible. Therefore, it is possible to keep the supply amount of the sinterable metal bonding material 22 constant while suppressing the generation of the aggregates 11 .

In the method of manufacturing a semiconductor device described above, the total width W2 of the recessed portion 8 and the opening portion 7 is smaller than the length W3 of the squeegee 9 . In this case, it is possible to reliably bring the squeegee 9 into contact with the first surface 6a of the metal mask 6 outside the recess 8 when performing the screen printing method.

In the method of manufacturing a semiconductor device described above, in the supply step (S2), the total length L3 of the recesses 8 and the openings 7 in the movement direction of the squeegee 9 is the contact area of the squeegee 9 with the first surface 6a of the metal mask 6. longer than the distance L2 moved in contact with 6aa. From a different point of view, in the above-described semiconductor device manufacturing method, in the supplying step (S2), the movement starting point 71 of the squeegee 9 in the moving direction of the squeegee 9 is the recessed portion 8 located on one side of the opening 7 in the moving direction. placed in a position overlapping the Further, an operation end point 72 of the squeegee 9 in the movement direction is arranged at a position overlapping the recessed portion 8 located on the other side of the opening 7 in the movement direction. In this case, since the recessed portion 8 is formed outside the edge of the opening 7 in the moving direction of the squeegee 9, it is ensured that the squeegee 9 comes into contact with the edge of the opening 7 when performing the screen printing method. can be prevented.

Embodiment 2.
<Method for manufacturing a semiconductor device>
FIG. 12 is a schematic diagram showing a squeegee used in the method of manufacturing a semiconductor device according to the second embodiment. 13 and 14 are schematic diagrams for explaining the method of manufacturing the semiconductor device according to the second embodiment. FIG. 13 shows the step of applying the sinterable metal bonding material 22 to the surface of the substrate 1 using the screen printing method in the step (S2) shown in FIG. FIG. 14 shows a sinterable metal bonding material 22 placed on the surface of the substrate 1 by removing the metal mask 6 from the substrate 1 after the step shown in FIG. 13, referring to FIGS. , the manufacturing method of the semiconductor device according to the second embodiment will be described.

The method for manufacturing a semiconductor device according to the second embodiment basically has the same configuration as the method for manufacturing a semiconductor device according to the first embodiment. The configurations of mask 6 and squeegee 9 are different from those of the semiconductor device manufacturing method according to the first embodiment. That is, in the squeegee 9 used in the method of manufacturing the semiconductor device according to the second embodiment, the squeegee recess 14 having the depth T2 is formed in the intermediate portion of the end face facing the metal mask 6 in the supply step (S2). there is As shown in FIG. 13, the width W5 of the squeegee recesses 14 is greater than the individual width W4 of the openings 7, and the width W5 of the squeegee recesses 14 is equal to the width W1 of the openings 7 shown in FIG. width of the region where the opening 7 is formed). 3, the end portions 9a located on both sides of the squeegee recess 14 on the end surface of the squeegee 9 come into contact with the contact regions 6aa of the metal mask 6, as shown in FIG.

A metal mask 6 used in the method of manufacturing a semiconductor device according to the second embodiment has openings 7 as shown in FIG. ) are not formed. That is, in the metal mask 6 shown in FIG. 13, the opening 7 is formed so as to penetrate from the first surface 6a to the second surface 6b, and the opening width of the opening 7 on the first surface 6a and the second surface The opening width of the opening 7 at 6b is substantially the same. In the step (S2) of FIG. 3, the contact regions 6aa of the metal mask 6 with which the end portion 9a of the squeegee 9 contacts are arranged so as to sandwich the opening 7 as shown in FIG. From a different point of view, the contact regions 6aa are arranged so as to sandwich the opening 7 in the width direction (the direction indicated by the arrow 33 in FIG. 13) orthogonal to the movement direction of the squeegee 9 in step (S2). In step (S2), contact region 6aa is arranged with opening 7 and a space therebetween. That is, the end surface of the squeegee 9 does not contact the edge 7a of the opening 7 on the first surface 6a. The squeegee 9 contacts the first surface 6a of the metal mask 6 at the two contact regions 6aa, so that parallelism between the bottom surface of the squeegee recess 14 and the surface 1a of the substrate 1 is ensured.

The depth T2 of the squeegee concave portion 14 in the squeegee 9 is set to a sufficient size so that the squeegee 9 does not come into contact with the edge 7a of the opening 7 of the metal mask 6 even if the squeegee 9 is deformed in step (S2). is preferred.

13 and 14, the total thickness T3 of the thickness T1 of the metal mask 6 (that is, the depth of the opening 7) and the depth T2 of the squeegee recess 14 is applied in step (S2). It is the thickness of the sinterable metal bonding material 22 . The depth T2 of the squeegee recess 14 can be set to 50 μm, for example. Moreover, the thickness T1 of the metal mask 6 can be set to 100 μm, for example. In this case, the thickness of the supplied sinterable metal bonding material 22 is 150 μm.

As a method for forming the squeegee recesses 14, any method such as mechanical polishing, laser processing, or etching with a chemical solution can be used. In this embodiment, the amount of deformation of the squeegee 9 is directly related to the supply stability of the sinterable metal bonding material 22 . Therefore, as the material of the squeegee 9, it is desirable to use a material having as high hardness as possible and less deformation. For example, a stainless steel plate having a thickness of about 1 mm can be used as the material of the squeegee 9 .

The step (S2) shown in FIG. 3 is performed using the metal mask 6 and the squeegee 9 shown in FIGS. 1, the semiconductor device according to the present embodiment can be obtained.

<Effect>
In the method of manufacturing the semiconductor device described above, the squeegee recess 14 is formed in the intermediate portion of the end face facing the metal mask 6 in the supply step (S2) shown in FIG. The width W5 of the squeegee recess 14 is larger than the width W4 of the opening 7. In the supplying step (S2), the end portions 9a located on both sides of the squeegee recess 14 on the end face of the squeegee 9 are in contact with the contact regions 6aa of the metal mask 6. Contact. In the metal mask 6, the contact regions 6aa are arranged so as to sandwich the opening 7 and are separated from the opening 7. As shown in FIG.

In this way, as in the method of manufacturing the semiconductor device according to the first embodiment, by forming the squeegee recesses 14, the surface portion 1aa of the substrate 1 where the sinterable metal bonding material 22 is arranged and the metal mask 6 are formed. can be spaced apart from the contact area 6aa with which the squeegee 9 contacts. As a result, since the edge 7a of the opening 7 and the squeegee 9 do not come into contact with each other, the sinterable metal bonding material 22 is sandwiched between the edge 7a of the opening 7 and the squeegee 9 and receives shear stress. It is possible to suppress the occurrence of problems such as formation of aggregates. Therefore, it is possible to suppress the occurrence of the problem that the semiconductor element 3 constituting the semiconductor device 4 (see FIG. 2) is damaged due to the existence of the aggregates, and as a result, it is possible to improve the reliability of the semiconductor device.

In the method of manufacturing a semiconductor device described above, in the supply step (S2), the width W5 of the squeegee recess 14 is larger than the width W4 of the opening 7 in the width direction perpendicular to the moving direction of the squeegee 9 . In this case, the contact area 6aa where the end 9a of the squeegee 9 contacts the metal mask 6 can be easily arranged at a position away from the opening 7. FIG.

In the method of manufacturing a semiconductor device described above, metal mask 6 includes a first surface 6a and a second surface 6b. A squeegee 9 contacts the first surface 6a. The second surface 6b is positioned opposite to the first surface 6a and faces the front surface 1a of the substrate 1 . The opening 7 is formed to reach from the first surface 6a to the second surface 6b. In the supplying step (S2), the end surface of the squeegee 9 does not contact the edge 7a of the opening 7 on the first surface 6a.

In this case, the sinterable metal bonding material 22 is sandwiched between the edge 7a of the opening 7 and the squeegee 9, and the sinterable metal bonding material 22 is subjected to shear stress to generate aggregates. can suppress the occurrence of

Embodiment 3.
<Structure of semiconductor device>
FIG. 15 is a schematic plan view of the semiconductor device according to the third embodiment. 16 is a schematic cross-sectional view taken along line XVI-XVI in FIG. 15. FIG. FIG. 17 is a schematic plan view for explaining the substrate of the semiconductor device according to the third embodiment.

A semiconductor device 41 shown in FIGS. 15 to 17 mainly includes a substrate 1 , a protective film 5 , a sinterable metal bonding material 22 and a semiconductor element 3 . The substrate 1 comprises a surface 1a. The surface 1a includes a surface portion 1aa to which the sinterable metal bonding material 22 is supplied, a region 1ab to be soldered in a post-process, and a region 1ac covered with the protective film 5. FIG. Region 1ac is a region other than surface portion 1aa and region 1ab on surface 1a. A material forming protective film 5 is, for example, a solder resist.

A semiconductor element 3 is bonded to the surface 1 a of the substrate 1 with a sinterable metal bonding material 22 . The protective film 5 is formed for the purpose of limiting the area where the solder wets and spreads when the terminal is soldered to the substrate 1 in a later process. The thickness T4 of the protective film 5 may be, for example, 0.001 mm or more and 0.5 mm or less, or may be 0.005 mm or more and 0.3 mm or less. The thickness T4d of protective film 5 may be, for example, 0.01 mm.

As shown in FIG. 15, a semiconductor device 41 has four semiconductor elements 3 on a substrate 1 in this embodiment. In the semiconductor device 41 , a plurality of semiconductor elements 3 may be arranged on the substrate 1 as shown in FIG. 15, or one semiconductor element 3 may be arranged on the substrate 1 . The number, type, shape, and arrangement of the semiconductor elements 3 can be arbitrarily determined according to the characteristics required of the semiconductor device 41, and are not limited to the configurations shown in FIGS. Needless to say, the effect of the present disclosure can be obtained even when the number, type, shape, and arrangement of the semiconductor elements 3 in the semiconductor device 41 are different from those shown in FIGS.

<Method for manufacturing a semiconductor device>
FIG. 18 is a schematic plan view showing a metal mask used in the method of manufacturing a semiconductor device according to the third embodiment. 19 is a schematic cross-sectional view along the line segment XIX-XIX in FIG. 18. FIG. 20 is a schematic cross-sectional view taken along line XX-XX in FIG. 18. FIG. 21 to 23 are schematic diagrams for explaining the method of manufacturing the semiconductor device according to the third embodiment.

The semiconductor device manufacturing method according to the present embodiment basically has the same configuration as the semiconductor device manufacturing method shown in FIG. The structure of the metal mask 61 is different from the manufacturing method of the semiconductor device shown in FIG. That is, the metal mask 61 shown in FIGS. 18 to 20 differs from the metal mask 6 shown in FIGS. 3 and 4 in the shape of the concave portion 8. FIG. A specific description will be given below.

A metal mask 61 shown in FIGS. 18 to 20 has a first surface 6a in contact with the squeegee 9 and a second surface located opposite to the first surface 6a, similarly to the metal mask 6 shown in FIGS. 2 faces 6b. In the metal mask 61, an opening 7 penetrating from the first surface 6a to the second surface 6b is formed. The position and size of the opening 7 are the same as the position and size of the surface portion 1aa of the substrate 1 . In other words, the metal mask 6 is placed on the surface 1a of the substrate 1 so that the surface portion 1aa of the substrate 1 is exposed. can be selectively supplied with a sinterable metal bonding material 22. A groove 10 is formed around the opening 7 in the second surface 6b of the metal mask 61, as shown in FIG.

The planar shape of recess 8 provided in first surface 6a of metal mask 61 is different from the planar shape of recess 8 of metal mask 6 shown in FIGS. In the metal mask 61, recesses 8 are formed on the first surface 6a so as to sandwich the opening 7 in the moving direction of the squeegee 9 indicated by the arrow 31, as shown in FIGS. In the width direction perpendicular to the moving direction of the squeegee 9, the width W4 of the recess 8 (see FIG. 19) is the same as the width W4 of the opening 7 (see FIG. 20). The total length of recess 8 and opening 7 is length L3. From a different point of view, in the moving direction of the squeegee 9 indicated by the arrow 31, the distance between both ends of the recess 8 is the length L3. The length L3 is longer than the distance L2 that the squeegee 9 is moved while in contact with the contact region 6aa of the first surface 6a of the metal mask 61 . In this embodiment, the width W4 is, for example, 15 mm, the length L3 is, for example, 250 mm, and the distance L2 is, for example, 100 mm. The thickness of the metal mask 61 is the same as the thickness T1 of the metal mask 6 shown in FIG. The depth from the first surface 6 a to the bottom of the recess 8 in the metal mask 61 is the same as the depth from the first surface 6 a to the bottom of the recess 8 in the metal mask 6 .

1, the contact area 6aa of the metal mask 61 is pressed against the substrate 1 by the squeegee 9 with a force of 1 kgf or more and 30 kgf or less, as indicated by an arrow 34 in FIG. The second surface 6b of the substrate 1 and the surface of the protective film 5 of the substrate 1 are in close contact with each other. For example, the force for pressing the squeegee 9 toward the substrate 1 may be 5 kgf.

On the other hand, when a gap is formed between the second surface 6b of the metal mask 61 and the protective film 5 of the substrate 1 as shown in FIG. (Part 22b of the sinterable metal bonding material 22 may bleed into the gap). As a result, after the metal mask 61 is removed from the substrate 1, a portion 22b of the sinterable metal bonding material 22 spreads over the protective film 5 as shown in FIG. The viscosity of the sinterable metal bonding material 22 is, for example, 1 Pa·s or more and 150 Pa·s or less. As an example, the viscosity of the sinterable metal bonding material 22 used in the present embodiment may be 30 Pa·s. Needless to say, the lower the viscosity, the more easily the capillary phenomenon occurs, and the sinterable metal bonding material 22 easily spreads into the gap.

In the metal mask 61, contact regions 6aa that come into contact with the squeegee 9 are present near the opening 7 and at both ends in the width direction. Therefore, the metal mask 61 and the surface of the protective film 5 of the substrate 1 (the surface 1a of the substrate 1 when the protective film 5 is not formed) can be brought into close contact. As a result, there is no gap between the surface of the protective film 5 of the substrate 1 and the second surface 6b of the metal mask 61 (or between the surface 1a of the substrate 1 and the second surface 6b of the metal mask 61). A sinterable metal bonding material 22 can be filled into the openings 7 . As a result, it is possible to prevent the portion 22b of the sinterable metal bonding material 22 from extending (bleeding) onto a region other than the surface portion 1aa on the substrate 1, that is, onto the protective film 5 such as a solder resist.

<Effect>
A method of manufacturing a semiconductor device according to the present disclosure includes a step of preparing a substrate (S1), a step of supplying (S2), and a step of bonding (S5). In the supplying step (S2), the sinterable metal bonding material 22 is supplied onto the surface 1a of the substrate 1. As shown in FIG. In the bonding step ( S<b>5 ), the semiconductor element 3 is bonded to the substrate 1 via the sinterable metal bonding material 22 . In the supply step (S2), a metal mask 6 having an opening 7 is placed on the surface 1a of the substrate 1, and a squeegee 9 is used to sinter the surface portion 1aa of the substrate 1 exposed inside the opening 7. A flexible metal bonding material 22 is supplied. In the supply step ( S<b>2 ), the contact areas 6 aa of the metal mask 6 with which the squeegee 9 contacts are arranged only on both sides of the opening 7 in the width direction orthogonal to the movement direction of the squeegee 9 .

In this way, sufficient stress can be applied from the squeegee 9 to the metal mask 6 on both sides of the opening 7 in the width direction. Therefore, it is possible to suppress the formation of gaps between the metal mask 6 and the surface of the substrate 1 (the surface of the protective film 5 of the substrate 1) on both sides of the opening 7 in the width direction. As a result, the portion 22b of the sinterable metal bonding material 22 can be prevented from partially oozing (extending) onto the surface of the substrate 1 (on the surface of the protective film 5 of the substrate 1).

Here, the sinterable metal bonding material 22 is fixed on the substrate 1 by achieving direct metal bonding with the metal exposed on the surface portion 1aa of the substrate 1 by heating and pressing. However, as shown in FIG. 23, a portion 22b of the sinterable metal bonding material 22 that oozes onto the protective film 5 on the substrate 1 is prevented from being bonded to the substrate 1 by the protective film 5, and is not bonded. That is, the part 22b of the sinterable metal bonding material 22 that oozes out onto the protective film 5 may peel off and become a conductive foreign matter in the subsequent process. Conductive foreign matter may cause poor insulation and degrade the performance of the semiconductor device 41 .

As described above, by manufacturing the semiconductor device 41 using the metal mask 61 according to the present embodiment, product defects caused by bleeding of the sinterable metal bonding material 22 as described above are suppressed. becomes possible.

In the method of manufacturing a semiconductor device described above, the metal mask 61 includes a first surface 6a with which the squeegee 9 contacts, and a second surface 6b. The second surface 6b is positioned opposite to the first surface 6a and faces the front surface 1a of the substrate 1 . The opening 7 is formed to reach from the first surface 6a to the second surface 6b. A first surface 6 a of the metal mask 61 is formed with recesses 8 that sandwich the opening 7 in the moving direction of the squeegee 9 and that are continuous with the opening 7 . A width W4 of the opening 7 in the width direction orthogonal to the moving direction of the squeegee 9 (see FIG. 20) is the same as the width W4 of the recess 8 in the width direction (see FIG. 19).

In this case, similarly to the manufacturing method of the semiconductor device according to the first embodiment, by forming the concave portion 8, the surface portion 1aa of the substrate 1 on which the sinterable metal bonding material 22 is arranged is increased in the movement direction of the squeegee 9. and the first surface 6a of the metal mask 6 can be spaced apart. As a result, the edge of the opening 7 in the moving direction of the squeegee 9 does not come into contact with the squeegee 9, so that the sinterable metal bonding material 22 is sandwiched between the edge of the opening 7 and the squeegee 9 and sheared. It is possible to suppress the occurrence of problems such as the generation of aggregates due to stress. Therefore, the reliability of the semiconductor device can be improved as in the method of manufacturing the semiconductor device according to the first embodiment.

In the method of manufacturing a semiconductor device described above, in the supply step (S2), the total length L3 of the recesses 8 and the openings 7 in the movement direction of the squeegee 9 is the contact area of the squeegee 9 with the first surface 6a of the metal mask 61. longer than the distance L2 moved in contact with 6aa. From a different point of view, in the above-described semiconductor device manufacturing method, in the supplying step (S2), the movement starting point 71 of the squeegee 9 in the moving direction of the squeegee 9 is the recessed portion 8 located on one side of the opening 7 in the moving direction. placed in a position overlapping the Further, an operation end point 72 of the squeegee 9 in the movement direction is arranged at a position overlapping the recessed portion 8 located on the other side of the opening 7 in the movement direction. In this case, since the recessed portion 8 is formed outside the edge of the opening 7 in the moving direction of the squeegee 9, it is ensured that the squeegee 9 comes into contact with the edge of the opening 7 when performing the screen printing method. can be prevented.

In the method of manufacturing a semiconductor device according to each of the above-described embodiments, the step of joining (S5) includes placing the semiconductor element on the sinterable metal joining material 22 supplied to the surface portion 1aa of the substrate 1 in the step of supplying (S2). 3 is included. In this case, a semiconductor device in which the semiconductor element 3 is bonded onto the sinterable metal bonding material 22 can be obtained.

(Example)
<Sample>
Example samples:
As a substrate, a ceramic substrate made of silicon nitride and copper plates as conductor layers were connected to both sides thereof was prepared. The copper plate is fixed to the ceramic substrate with brazing material. As the brazing material, an Ag--Cu--Ti brazing material containing silver and copper as main components and titanium (Ti) added as an activator was used. The thickness of the ceramic substrate described above was 0.3 mm, and the thickness of the copper plate was 0.4 mm.

As the sinterable metal bonding material 22, a sinterable metal bonding material using nanometer-level silver (Ag) particles as metal fine particles was prepared. As the metal mask 6 and the squeegee 9, the metal mask 6 and the squeegee 9 having the configurations used in the method of manufacturing the semiconductor device according to the first embodiment were prepared. Specifically, stainless steel was used as the material of the metal mask 6 . The thickness T1 of the metal mask 6 was 150 μm, the depth of the recess 8 was 40 μm, and the planar shape of the opening 7 was a square of 30 mm×30 mm. The width W2 (see FIG. 3) of the recess 8 in the width direction orthogonal to the moving direction of the squeegee 9 was set to 40 mm. A recess 8 was formed in a range of −100 mm to +100 mm from the center of the opening 7 in the movement direction of the squeegee 9 . That is, the length L3 (see FIG. 3) of the concave portion 8 in the moving direction of the squeegee 9 was set to 200 mm.

As the squeegee 9, a plate material made of polyester resin and having a thickness of 0.2 mm was used. The length W3 of the squeegee 9 was set to 50 mm.

Conventional sample:
The substrate, sinterable metal bonding material, and squeegee 9 were the same as those of the above-described examples. On the other hand, as the metal mask of the sample of the conventional example, a metal mask having basically the same structure as the metal mask of the sample of the above-described example, but without the concave portion 8, was prepared. 100 substrates were prepared as samples for each of the example and the comparative example.

<Test method>
Using each of the sample of the example and the sample of the conventional example, a sinterable metal bonding material was applied to the surface of the substrate by screen printing using the metal mask 6 and the squeegee 9 described above. After that, a drying step was performed. Next, the surface of the sinterable metal bonding material was photographed, and the size and number of formed aggregates were measured by image processing.

The application of the sinterable metal bonding material by screen printing was specifically carried out as follows. In the case of the sample of the example, first, a sinterable metal bonding material is supplied in the vicinity of the opening 7 of the metal mask and on the recess 8 . The metal mask 6 and the squeegee 9 are brought into contact with each other at locations other than the recesses 8 with a pressing force of 3 kgf. The squeegee 9 waits at a position -60 mm from the center of the opening 7 of the metal mask 6 on one side (front side) in the moving direction of the squeegee 9 . Then, the squeegee 9 is driven toward the opening 7 of the metal mask 6 at a speed of 50 mm/s to a position +60 mm on the other side (back side) in the movement direction of the squeegee 9 . Thereafter, the squeegee 9 is again driven in the opposite direction from the position of +60 mm on the far side to the position of -60 mm on the front side. In this manner, the squeegee 9 reciprocates to fill the openings 7 of the metal mask 6 with the sinterable metal bonding material in both directions. In the case of the sample of the comparative example, the sinterable metal bonding material is supplied on the surface of the metal mask in the vicinity of the opening 7 of the metal mask. After that, the squeegee 9 is driven in the same manner as in the case of the sample of the above-described embodiment.

In this way, after the reciprocating motion of the squeegee 9 is completed, the metal mask 6 is separated from the substrate 1 by lowering the substrate by 0.3 mm at, for example, 100 mm/s. As a result, the sinterable metal bonding material is supplied onto the substrate. After that, the substrate supplied with the sinterable metal bonding material 22 is heated to perform a drying process for volatilizing excess organic components contained in the sinterable metal bonding material. The conditions for the drying process were a heating temperature of 100° C. and a drying time of 30 minutes.

<Results>
FIG. 24 is a graph showing the relationship between the number and size of aggregates for the samples of Examples and Comparative Examples. In the graph shown in FIG. 24, the vertical axis indicates the number of detected aggregates, and the horizontal axis indicates the sizes of the aggregates. On the horizontal axis, the number of aggregates with a size of 50 μm or more and less than 100 μm is shown on the left side, and the number of aggregates with a size of 100 μm or more is shown on the right side. FIG. 24 shows the number of aggregates generated per 100 substrates. In FIG. 24, the data of the sample of the conventional example is shown by a bar graph hatched with diagonal lines falling to the right, and the data of the sample of the example is shown by a bar graph hatched with diagonal lines falling to the left. As can be seen from FIG. 24, the sample of the example of the present disclosure suppresses the generation of aggregates compared to the sample of the conventional example.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. As long as there is no contradiction, at least two of the embodiments disclosed this time may be combined. The basic scope of the present disclosure is indicated by the scope of claims rather than the above description, and is intended to include all changes within the meaning and scope of equivalence to the scope of claims.

Reference Signs List 1 substrate 1a surface 1aa surface portion 2 bonding layer 3 semiconductor element 4, 41 semiconductor device 5 protective film 6, 61 metal mask 6a first surface 6aa contact region 6b second surface 7 opening part, 7a edge, 8 recess, 9 squeegee, 9a end, 10 groove, 11 aggregate, 12 crack, 14 squeegee recess, 22, 22a sinterable metal bonding material, 22b part, 31, 32, 33, 34 arrow, 71 motion start point, 72 motion end point.

Claims (8)

preparing a substrate;
providing a sinterable metal bonding material on the surface of the substrate;
bonding a semiconductor element to the substrate via the sinterable metal bonding material;
In the supplying step, a metal mask having an opening is placed on the surface of the substrate, and the sinterable metal bonding material is applied to the surface portion of the substrate exposed inside the opening using a squeegee. supply and
In the supplying step, in a plan view, the surface portion of the substrate to which the sinterable metal bonding material is supplied and the contact area of the metal mask with which the squeegee contacts are arranged with a gap therebetween ,
The metal mask includes a first surface with which the squeegee contacts, and a second surface opposite to the first surface and facing the surface of the substrate,
the opening is formed to reach from the first surface to the second surface;
a concave portion surrounding the opening and continuing to the opening is formed on the first surface of the metal mask;
In the supplying step, the total length of the recess and the opening in the moving direction of the squeegee is greater than the distance the squeegee is moved while in contact with the contact region of the first surface of the metal mask. Also long , a method of manufacturing a semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1 , wherein the total width of said recess and said opening is smaller than the length of said squeegee. In the supplying step,
The movement starting point of the squeegee in the movement direction of the squeegee is arranged at a position overlapping the recess located on one side of the opening in the movement direction,
3. The method of manufacturing a semiconductor device according to claim 1 , wherein an end point of operation of said squeegee in said moving direction is arranged at a position overlapping said recess located on the other side of said opening in said moving direction . . preparing a substrate;
providing a sinterable metal bonding material on the surface of the substrate;
bonding a semiconductor element to the substrate via the sinterable metal bonding material;
In the supplying step, a metal mask having an opening is placed on the surface of the substrate, and the sinterable metal bonding material is applied to the surface portion of the substrate exposed inside the opening using a squeegee. supply and
In the supplying step, in a plan view, the surface portion of the substrate to which the sinterable metal bonding material is supplied and the contact area of the metal mask with which the squeegee contacts are arranged with a gap therebetween,
The squeegee has a squeegee concave portion formed in an intermediate portion of the end face facing the metal mask in the supplying step,
The width of the squeegee recess is larger than the width of the opening,
In the supplying step, the end portions located on both sides of the squeegee recess on the end face of the squeegee are in contact with the contact region of the metal mask,
The method of manufacturing a semiconductor device, wherein in the metal mask, the contact regions are arranged so as to sandwich the opening and are separated from the opening. 5. The method of manufacturing a semiconductor device according to claim 4 , wherein in said supplying step, the width of said squeegee recess is larger than the width of said opening in the width direction orthogonal to the moving direction of said squeegee. The metal mask includes a first surface with which the squeegee contacts, and a second surface opposite to the first surface and facing the surface of the substrate,
the opening is formed to reach from the first surface to the second surface;
6. The method of manufacturing a semiconductor device according to claim 4 , wherein in said supplying step, said end surface of said squeegee does not contact the edge of said opening on said first surface. preparing a substrate;
providing a sinterable metal bonding material on the surface of the substrate;
bonding a semiconductor element to the substrate via the sinterable metal bonding material;
In the supplying step, a metal mask having an opening is placed on the surface of the substrate, and the sinterable metal bonding material is applied to the surface portion of the substrate exposed inside the opening using a squeegee. supply and
In the supplying step, the contact areas of the metal mask with which the squeegee contacts are arranged only on both sides of the opening in the width direction orthogonal to the movement direction of the squeegee ,
The metal mask includes a first surface with which the squeegee contacts, and a second surface opposite to the first surface and facing the surface of the substrate,
the opening is formed to reach from the first surface to the second surface;
recesses are formed on the first surface of the metal mask so as to sandwich the opening in the moving direction of the squeegee and are connected to the opening;
The width of the opening in the width direction is the same as the width of the recess in the width direction,
In the supplying step, the total length of the recess and the opening in the moving direction of the squeegee is greater than the distance the squeegee is moved while in contact with the contact region of the first surface of the metal mask. Also long , a method of manufacturing a semiconductor device. 8. The bonding step includes bonding the semiconductor element onto the sinterable metal bonding material supplied to the surface portion of the substrate in the supplying step. 2. A method for manufacturing a semiconductor device according to item 1.

Images