JP6387048B2 - Manufacturing method of semiconductor device - Google Patents

Description

The present invention relates to a method of manufacturing a semiconductor device, more particularly to a method of manufacturing a semiconductor device that wirelessly joining the mounting substrate and the semiconductor device via the metal particle layer.

  Currently, many research institutions are conducting research and development of silicon carbide (SiC) devices. Characteristics of the SiC device include low on-resistance, high-speed switching, and high-temperature operation.

  Conventionally, in an Si device such as an insulated gate bipolar transistor (IGBT) used in the field of semiconductor power modules, the operable temperature range is up to about 150 ° C., so the conventional Sn-Ag system It was possible to drive even using low melting point solder such as.

  A method for interconnecting SiC devices and a low thermal resistance package have already been disclosed (see, for example, Patent Document 1 and Patent Document 2). Patent Document 1 and Patent Document 2 disclose a method of forming a package that accommodates a SiC device, and the SiC device is liquid phase diffusion (TLP: Transient Liquid Phase) with respect to other components or conductive surfaces. Bonded using bonding technology.

  An apparatus that cools a semiconductor element from the back surface via a cooler is also disclosed (for example, see Patent Document 3).

  In addition, there is a mounting technique in which a columnar electrode is formed on a semiconductor chip, a solder bump is formed on the columnar electrode, and the substrate electrode is directly electrically connected to the substrate via the solder bump (see, for example, Patent Document 4). .)

International Publication No. 2006/074165 US Patent Application Publication No. 2006/0151871 JP 2010-245329 A JP 2010-199255 A

  A SiC device can theoretically operate at a high temperature of 300 ° C. or more, and a conventional solder material melts a joint portion and causes short-circuit between electrodes, separation of the joint portion, and the like, thereby impairing reliability. It was.

  Further, since the SiC device has a lower resistance than the IGBT, the power density can be increased. Therefore, there is a problem that it is difficult to ensure reliability due to current concentration in wire bonding wiring using aluminum or copper wire, which is generally used for power devices.

An object of the present invention is to provide a method for manufacturing a semiconductor device having a low-cost and high heat-resistant wireless junction.

According to one aspect of the present invention for achieving the above object, a step of forming a signal wiring electrode on a mounting substrate, and a step of forming a power wiring electrode on or through the mounting substrate. Disposing a power device having a gate pad electrode electrically connectable to the signal wiring electrode and a source pad electrode electrically connectable to the power wiring electrode; and the signal wiring electrode or the gate pad Applying a first paste layer including a plurality of first metal fine particles and a first antioxidant film covering the plurality of first metal fine particles to one or both of the electrodes; and the power wiring electrode or the source pad A second paste layer including a plurality of second metal fine particles and a second antioxidant film covering the plurality of second metal fine particles is applied to one or both of the electrodes. And flip chip connecting the power device onto the mounting substrate, and the step of flip chip connecting the power device onto the mounting substrate includes the signal wiring electrode via the first paste layer. And the gate pad electrode are brought into contact with each other, and in the contact state, the mounting substrate and the power device are pressed in a direction facing each other to apply a predetermined pressure to the first paste layer, and the first oxidation prevention A step of bringing the plurality of first metal fine particles into close contact with each other on the surface where the film is crushed, firing the first paste layer at a predetermined temperature, and press-bonding the signal wiring electrode and the gate pad electrode; The power wiring electrode and the source pad electrode are brought into contact with each other through the second paste layer, and the mounting substrate and the power device are brought into contact with each other in the contact state. A predetermined pressure is applied to the second paste layer by pressing in the direction to face, the two second metal fine particles are brought into close contact with each other on the surface where the second antioxidant film is crushed, and the second paste layer is There is provided a method for manufacturing a semiconductor device, comprising baking at a temperature and press-bonding the power wiring electrode and the source pad electrode.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the semiconductor device which has high heat-resistant wireless junction at low cost can be provided.

FIG. 2 is a schematic plan pattern configuration diagram of the semiconductor device according to the first embodiment. FIG. 2 is a schematic cross-sectional structure diagram taken along line II in FIG. 1. (A) A schematic cross-sectional structure diagram showing a state before flip chip bonding of a semiconductor device, which is a step in the method for manufacturing a semiconductor device according to the first embodiment, and (b) a semiconductor device according to the embodiment. FIG. 4 is a schematic cross-sectional structure diagram of a mounting substrate corresponding to FIG. FIG. 4A is a schematic cross-sectional structure diagram showing a state before flip-chip bonding of a semiconductor device, which is one step of a method of manufacturing a semiconductor device according to Modification 1 of the first embodiment. The typical cross-section figure of the mounting substrate corresponding to a). FIG. 5A is a schematic cross-sectional structure diagram showing a state before flip chip bonding of a semiconductor device, which is one step of a method for manufacturing a semiconductor device according to Modification 2 of the first embodiment. The typical cross-section figure of the mounting substrate corresponding to a). FIG. 5 is a schematic cross-sectional structure diagram showing a pressurizing step in one step of the method of manufacturing the semiconductor device according to the first embodiment. The typical plane pattern block diagram of the semiconductor device which concerns on 2nd Embodiment. FIG. 8 is a schematic cross-sectional structure diagram taken along line II-II in FIG. 7. (A) A schematic cross-sectional structure diagram showing a state before flip-chip bonding of a semiconductor device, which is one step of a method for manufacturing a semiconductor device according to a second embodiment, and (b) a semiconductor device according to the embodiment. FIG. 10 is a schematic cross-sectional structure diagram of a mounting substrate corresponding to FIG. FIG. 10A is a schematic cross-sectional structure diagram showing a state before flip-chip bonding of a semiconductor device, which is a step in the method for manufacturing a semiconductor device according to Modification 1 of the second embodiment. The typical cross-section figure of the mounting substrate corresponding to a). FIG. 11A is a schematic cross-sectional structure diagram showing a state before flip-chip bonding of a semiconductor device, which is one step of a method for manufacturing a semiconductor device according to Modification 2 of the second embodiment. The typical cross-section figure of the mounting substrate corresponding to a). FIG. 10 is a schematic cross-sectional structure diagram showing a pressurizing step in one step of the method of manufacturing a semiconductor device according to the second embodiment. (A) Typical sectional drawing which shows the state before pressurizing silver nano paste as a apply | coated metal particle joining layer in one process of the manufacturing method of the semiconductor device which concerns on the 1st-2nd embodiment, (b) ) A schematic cross-sectional view showing the state of the pressed silver nanopaste. The typical circuit block diagram of the three-phase inverter comprised by applying the semiconductor device which concerns on the 1st-2nd embodiment. It is an example of the semiconductor device applied to the semiconductor device which concerns on the 1st-2nd embodiment, Comprising: The typical cross-section figure of SiC * MOSFET. FIG. 5 is a schematic cross-sectional structure diagram of a SiC MOSFET that includes a source pad electrode SP and a gate pad electrode GP, which is an example of a semiconductor device applied to the semiconductor device according to the first to second embodiments. (A) The typical plane pattern block diagram which shows the state which is one process of the manufacturing method of the semiconductor device which concerns on the 1st-2nd embodiment, and has arrange | positioned the mask for apply | coating a paste layer on a semiconductor substrate. (B) Typical cross-section figure along the III-III line of Fig.17 (a). The typical cross-section figure showing the state where it was 1 process of the manufacturing method of the semiconductor device concerning the 1st-2nd embodiment, and the paste layer was deposited on the mask which has an opening. FIG. 5 is a schematic cross-sectional structure diagram showing a process of filling a paste layer into a mask opening by moving a squeegee, which is a process of the method of manufacturing a semiconductor device according to the first to second embodiments. FIG. 5 is a schematic cross-sectional structure diagram showing a state in which a paste layer is filled in an opening of a mask, which is a step of the method for manufacturing a semiconductor device according to the first to second embodiments. FIG. 3 is a schematic cross-sectional structure diagram showing a state in which a columnar electrode and a heat spreader are arranged on the drain electrode in the semiconductor device according to the first embodiment. FIG. 6 is a schematic cross-sectional structure diagram showing a state in which a columnar electrode and a heat spreader are arranged on a drain electrode in a semiconductor device according to a second embodiment. The typical cross-section figure showing a comparative example. The typical cross-section figure showing a comparative example. The typical cross-section figure showing a comparative example.

  Next, embodiments will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention include the material, shape, structure, The layout is not specified as follows. Various modifications can be made to the embodiment of the present invention within the scope of the claims.

[First embodiment]
(Configuration of semiconductor device)
A schematic planar pattern configuration of the semiconductor device 1 according to the first embodiment is expressed as shown in FIG. 1, and a schematic cross-sectional structure taken along line II in FIG. 1 is expressed as shown in FIG. Is done. FIG. 1 corresponds to the planar pattern configuration seen from the drain electrode 36 side of the semiconductor device 16 arranged on the mounting substrate 8 in FIG.

  As shown in FIGS. 1 and 2, the semiconductor device 1 according to the first embodiment is disposed on the mounting substrate 8, the signal wiring electrode 12 disposed on the mounting substrate 8, and the mounting substrate 8. A semiconductor device 16 having a power wiring electrode 13, a gate pad electrode GP electrically connectable to the signal wiring electrode 12 and a source pad electrode SP electrically connectable to the power wiring electrode 13; a signal wiring electrode 12 and a gate; A first metal particle bonding layer 18G disposed between the pad electrode GP and a second metal particle bonding layer 18S disposed between the power wiring electrode 13 and the source pad electrode SP. Here, the semiconductor device 16 is flip-chip connected to the mounting substrate 8. That is, in the semiconductor device 16, the gate pad electrode GP and the source pad electrode SP are connected face-down with respect to the surface of the mounting substrate 8, and the drain electrode 36 includes the gate pad electrode GP and the source pad electrode SP. The semiconductor substrate 26 is disposed on a surface facing the surface of the semiconductor substrate 26 (surface opposite to the mounting substrate 8).

  Here, the first metal particle bonding layer 18G and the second metal particle bonding layer 18S are formed by firing a paste material containing conductive particles. The firing temperature of the paste material is, for example, about 200 to 400 ° C.

  The conductive particles are metal fine particles, such as silver particles, gold particles, nickel or copper particles.

  For example, when silver particles are applied as the metal fine particles, the concentration of the silver particles is, for example, about 80% by mass to about 95% by mass. The average particle size in the case of silver nanoparticles is about 10 nm to about 100 nm.

  Although not shown, a silver plating layer is formed on the interface of the power wiring electrode 13 in contact with the second metal particle bonding layer 18S, and the power wiring electrode 13 and the second metal particle bonding layer 18S It is also possible to further secure the adhesion.

  In FIG. 2, a drain electrode 36 is disposed above the semiconductor substrate 26. A gate pad electrode GP and a source pad electrode SP are disposed on the surface of the semiconductor substrate 26 facing the drain electrode 36.

  Although not particularly limited, the drain electrode 36, the gate pad electrode GP, and the source pad electrode SP are made of polysilicon, Al, Ni, or the like.

  In the first embodiment, the mounting board 8 is a plate-like printed board made of an insulating base material, and the power wiring electrodes 13 are arranged at predetermined positions on the mounting board 8. As shown in FIG. 2, the power wiring electrode 13 is disposed at a position facing the source pad electrode SP of the semiconductor device 16. The power wiring electrode 13 is formed of a thick copper foil. For example, a large current of about several hundred amperes can be passed through a thick copper foil having low resistance and excellent heat dissipation by the power wiring electrode 13.

  A signal wiring electrode 12 is disposed on the surface of the mounting substrate 8 facing the gate pad electrode GP of the semiconductor device 16. Here, the signal wiring electrode 12 may be formed of, for example, a copper thin film. The thickness of the copper thin film is, for example, about 30 to 70 μm.

(Silver nano paste and its sintered body)
The silver nanopaste is obtained by, for example, diffusing silver nanoparticles having a particle size of about 30 nm to about 100 nm in a predetermined solvent. As the solvent, for example, a polar solvent such as terpineol, a hydrocarbon solvent such as tetradecane, an aqueous solvent, a ketone solvent, or the like is applied.

  Silver nanoparticles have a structure in which the surface of fine silver particles as a nucleus is covered with a shell (organic shell) made of an organic compound or the like. Thereby, the dispersibility in the solvent can be improved and oxidation of the silver fine particles can be prevented. In addition, in the pre-process for performing the firing treatment, the density of silver fine particles can be increased by pressurizing the paste layer made of silver nanopaste and crushing the shell. Denseness can be improved. A specific method of pressurization will be described later with reference to FIG.

  Moreover, in 1st Embodiment, you may use the comparatively high concentration silver nano paste whose density | concentration of a silver nanoparticle is about 80 mass%-about 95 mass%, for example. This is because the metallic silver deposited by firing is made dense to ensure good conductivity and bondability.

  Moreover, in 1st Embodiment, the baking temperature of the paste layer which consists of silver nano paste is about 200-400 degreeC, for example.

  By this firing treatment, high melting point metal silver (melting point: about 960 ° C.) is deposited to form the metal particle bonding layers 18S, 18G. As a result, the source pad electrode SP and the power wiring electrode 13 are firmly bonded via the metal particle bonding layer 18S, and the gate pad electrode GP and the signal wiring electrode 12 are bonded via the metal particle bonding layer 18G. The space is firmly joined.

Moreover, since the metal particle bonding layers 18S and 18G exhibit the same characteristics as metallic silver (Ag), they are electrically low in resistance (about 2.08 × 10 ⁻⁸ [Ωm] at 100 ° C.). It has excellent thermal conductivity (about 429 W / mK at 300 K) and has a high heat resistance of about 960 ° C. as described above.

  Therefore, even when the SiC device is driven at a high temperature of, for example, about 400 ° C., the junction is not melted, and the reliability of the device characteristics and the reliability at the time of mounting can be improved.

(Method for manufacturing semiconductor device)
A schematic cross-sectional structure showing a state before the flip chip bonding of the semiconductor device 16 in one process of the method for manufacturing the semiconductor device 1 according to the first embodiment is expressed as shown in FIG. A schematic cross-sectional structure of the mounting substrate 8 corresponding to FIG. 3A is expressed as shown in FIG.

  FIG. 4A is a schematic cross-sectional view showing a state before the flip chip bonding of the semiconductor device 16, which is one step of the method for manufacturing the semiconductor device 1 according to the first modification of the first embodiment. The schematic cross-sectional structure of the mounting substrate 8 corresponding to FIG. 4A is expressed as shown in FIG.

  5A is a schematic cross-sectional view showing a state before the flip chip bonding of the semiconductor device 16, which is one step of the manufacturing method of the semiconductor device 1 according to the second modification of the first embodiment. The schematic cross-sectional structure of the mounting substrate 8 corresponding to FIG. 5A is expressed as shown in FIG.

  As shown in FIGS. 3 to 5, the method of manufacturing the semiconductor device according to the first embodiment includes a step of forming a signal wiring electrode 12 on the mounting substrate 8, and a step of forming the power wiring electrode 13 on the mounting substrate 8. Forming a semiconductor device 16 having a gate pad electrode GP electrically connectable to the signal wiring electrode 12 and a source pad electrode SP electrically connectable to the power wiring electrode 13, and a signal wiring A step of forming the first metal particle bonding layer 18G on one or both of the electrode 12 and the gate pad electrode GP, and a step of forming the second metal particle bonding layer 18S on one or both of the power wiring electrode 13 and the source pad electrode SP. And a step of flip-chip connecting the semiconductor device 16 onto the mounting substrate 8.

  Further, in the method of manufacturing the semiconductor device according to the first embodiment, the step of forming the first metal particle bonding layer 18G includes the step of forming the paste layer 18 containing conductive particles on either the signal wiring electrode 12 or the gate pad electrode GP. Alternatively, the step of forming the second metal particle bonding layer 18S includes a step of applying the paste layer 18 containing conductive particles to one or both of the power wiring electrode 13 and the source pad electrode SP. Have.

  In the method of manufacturing the semiconductor device according to the first embodiment, the step of flip-chip connecting the semiconductor device 16 to the mounting substrate 8 includes connecting the signal wiring electrode 12 and the gate pad electrode GP via the paste layer 18. In the contact state, the paste layer 18 is baked at a predetermined temperature to join the signal wiring electrode 12 and the gate pad electrode GP, and the power wiring electrode 13 and the source pad electrode SP through the paste layer 18. The paste layer 18 is fired at a predetermined temperature in the contact state, and the power wiring electrode 13 and the source pad electrode SP are joined.

  In the first embodiment, as shown in FIG. 3, metal particle bonding layers 18G and 18S are arranged on the mounting substrate 8 side. More specifically, the metal particle bonding layer 18 </ b> S is provided on the surface of the power wiring electrode 13, and the metal particle bonding layer 18 </ b> G is disposed on the surface of the signal wiring electrode 12.

  In Modification 1 of the first embodiment, as shown in FIG. 4, metal particle bonding layers 18G and 18S are arranged on the semiconductor device 16 side. More specifically, the metal particle bonding layer 18S is disposed on the source pad electrode SP, and the metal particle bonding layer 18G is disposed on the gate pad electrode GP.

  In the second modification of the first embodiment, as shown in FIG. 5, metal particle bonding layers 18G1, 18G2, 18S1, and 18S2 are disposed on both sides of the semiconductor device 16 and the mounting substrate 8, respectively. More specifically, the metal particle bonding layer 18S1 is disposed on the source pad electrode SP, the metal particle bonding layer 18G1 is disposed on the gate pad electrode GP, and the metal particle bonding layer 18S2 is disposed on the power wiring electrode 13. The metal particle bonding layer 18G2 is disposed on the signal wiring electrode 12. In consideration of the thickness of the metal particle bonding layer formed by firing with 18G1 and 18G2 and 18G2 and 18S1 being in close contact, the thickness of 18G1, 18G2, 18S1 and 18S2 is about 5 μm to about 5 μm, respectively. It is about 50 μm.

  In one step of the method for manufacturing the semiconductor device according to the first embodiment, the state before pressurizing the silver nanopaste as the applied metal particle bonding layer is schematically represented as shown in FIG. The state of the silver nanopaste after pressurization is schematically represented as shown in FIG.

  In FIG. 13A, each silver nanoparticle 22 is in a state of being diffused in a solvent 20 such as terpineol in a form covered with a shell (organic shell) 20a composed of an organic compound or the like. .

  When the paste layer 18 is compressed from this state by applying pressure P from above and below, the state changes to the state shown in FIG. That is, the shell 20a made of an organic compound or the like is crushed by pressurization, and the silver nanoparticles 22 are in close contact with each other. As a result, the thickness of the paste layer 18 is reduced from L1 to L2.

  For the application of the paste layer 18 for forming the metal particle bonding layers 18G and 18S, a screen printing method using a mask 25 and a squeegee (scalar member) 27 described later is applied.

  Further, the thickness of the paste layer 18 is, for example, about 10 μm to about 50 μm. The thicknesses of the metal particle bonding layers 18G and 18S are about half of the thickness of the paste layer 18 due to shrinkage during firing. That is, for example, when the thickness of the paste layer 18 is about 50 μm, it has been confirmed by experiments that the thickness of the fired metal particle bonding layers 18G and 18S is about 20 μm to about 30 μm.

(Pressurization and heating process)
A schematic cross-sectional structure showing a pressurizing process, which is a process of the method for manufacturing the semiconductor device according to the first embodiment, is expressed as shown in FIG.

  In the first embodiment or the modified examples 1 and 2, as shown in FIG. 6, a semiconductor is mounted on the mounting substrate 8 with the metal particle bonding layers 18G and 18S (the paste layer 18 before heating and pressurization) sandwiched therebetween. The device 16 is aligned and placed in a face-down state, and in that state, the device 16 is set on the press machine 120 (120a, 120b) and pressure is applied in the direction of arrow P.

  The pressure at this time is, for example, about 2 MPa to about 30 MPa. Thereby, the paste layer 18 will be in the state which each silver nanoparticle 22 closely_contact | adhered like FIG.13 (b) from the state of Fig.13 (a).

  In the above pressurization step, since the pressurization and heating are performed simultaneously, although not shown, the entire semiconductor device is heated at about 200 ° C. to about 400 ° C. for a predetermined time by a predetermined baking apparatus or the like.

  Thereby, the paste layer 18 is baked, and metal silver is deposited to form the metal particle bonding layers 18G and 18S.

  The metal particle bonding layers 18G and 18S made of metallic silver firmly bond the gate pad electrode GP and the signal wiring electrode 12 and the source pad electrode SP and the power wiring electrode 13 to form a semiconductor device on the mounting substrate 8. 16 is electrically joined in a face-down state.

  According to 1st Embodiment and its modifications 1-2, the wireless joining provided with high heat resistance can be formed by the simple process of apply | coating and baking silver nano paste.

  Moreover, according to 1st Embodiment and its modifications 1-2, heat resistance of a metal particle joining layer, heat | fever are formed by forming a metal particle joining layer with the metallic silver which is a sintered compact of silver nanopaste. Conductivity can be increased, and a semiconductor device suitable for a semiconductor device such as a SiC-based FET or a GaN-based FET can be provided.

  Moreover, according to 1st Embodiment and its modifications 1-2, a metal particle joining layer is formed with metal silver, and since lead (Pb) is not used, it becomes lead-free and contributes to pollution measures. it can.

  According to 1st Embodiment and its modifications 1-2, the semiconductor device which has low heat and high heat-resistant wireless, and its manufacturing method can be provided.

[Second Embodiment]
(Configuration of semiconductor device)
A schematic planar pattern configuration of the semiconductor device 1 according to the second embodiment is expressed as shown in FIG. 7, and a schematic cross-sectional structure taken along line II-II in FIG. 7 is expressed as shown in FIG. Is done. FIG. 7 corresponds to the planar pattern configuration viewed from the drain electrode 36 side of the semiconductor device 16 disposed on the mounting substrate 8 in FIG.

  As shown in FIGS. 7 and 8, the semiconductor device 1 according to the second embodiment is disposed through the mounting substrate 8, the signal wiring electrode 12 disposed on the mounting substrate 8, and the mounting substrate 8. A power pad electrode 6, a gate pad electrode GP electrically connectable to the signal line electrode 12, and a semiconductor device 16 having a source pad electrode SP electrically connectable to the power line electrode 6, and the signal line electrode 12 And a first metal particle bonding layer 18G disposed between the gate pad electrode GP and a second metal particle bonding layer 18S disposed between the power wiring electrode 6 and the source pad electrode SP. Here, the semiconductor device 16 is flip-chip connected to the mounting substrate 8. That is, in the semiconductor device 16, the gate pad electrode GP and the source pad electrode SP are connected face-down with respect to the surface of the mounting substrate 8, and the drain electrode 36 includes the gate pad electrode GP and the source pad electrode SP. The semiconductor substrate 26 is disposed on a surface facing the surface of the semiconductor substrate 26 (surface opposite to the mounting substrate 8).

  In the second embodiment, by providing the power wiring electrode 6 disposed through the mounting substrate 8, a semiconductor device 16 having a larger current than that of the first embodiment is formed on the mounting substrate 8. It can be installed.

  Here, the first metal particle bonding layer 18G and the second metal particle bonding layer 18S are formed by firing a paste material containing conductive particles. The firing temperature of the paste material is, for example, about 200 to 400 ° C.

  The conductive particles are metal fine particles, for example, silver particles, gold particles, copper particles, or nickel particles.

  For example, when silver nanoparticles are applied as the metal fine particles, the concentration of silver nanoparticles is, for example, about 80% by mass to about 95% by mass. The silver nanoparticles have a particle size of about 10 nm to about 100 nm.

  In the second embodiment, the mounting board 8 is a plate-like printed board made of an insulating base material, and has a configuration in which the power wiring electrode 6 is embedded at a predetermined position of the mounting board 8. As shown in FIG. 8, the power wiring electrode 6 is embedded at a position facing the source pad electrode SP of the semiconductor device 16. The power wiring electrode 6 is formed of, for example, a thick copper plate having a thickness of about 0.5 to 1.0 mm. The power wiring electrode 6 can energize the mounting substrate 8 in the thickness direction and the planar direction even with a large current of about several hundred amperes, for example, through a thick copper plate having low resistance and excellent heat dissipation.

  As the second metal particle bonding layer 18S, for example, when a paste layer made of silver nanopaste and a sintered body thereof are applied, the source is improved in order to improve the bonding property with the second metal particle bonding layer 18S. A silver plating layer 19 may be formed on the surface of the power wiring electrode 6 facing the pad electrode SP.

  In the semiconductor device 1 according to the second embodiment, as a metal nano paste between the silver plating layer 19 and the source pad electrode SP and between the signal wiring electrode 12 and the gate pad electrode GP, for example, silver Metal particle bonding layers 18S and 18G obtained by firing the nanopaste are respectively disposed.

  The silver plating layer 19 and the source pad electrode SP and the signal wiring electrode 12 and the gate pad electrode GP are electrically bonded via the metal particle bonding layers 18S and 18G.

  A signal wiring electrode 12 is disposed on the surface of the mounting substrate 8 facing the gate pad electrode GP of the semiconductor device 16. Here, the signal wiring electrode 12 may be formed of, for example, a copper thin film. The thickness of the copper thin film is, for example, about 15 to about 70 μm.

  The silver nanopaste and its sintered body that can be applied in the semiconductor device 1 according to the second embodiment are the same as those in the first embodiment, and therefore redundant description is omitted.

(Method for manufacturing semiconductor device)
A schematic cross-sectional structure showing a state before the flip chip bonding of the semiconductor device 16 as a process of the method for manufacturing the semiconductor device 1 according to the second embodiment is expressed as shown in FIG. A schematic cross-sectional structure of the mounting substrate 8 corresponding to FIG. 9A is expressed as shown in FIG.

  10A is a schematic cross-sectional view showing a state before the flip chip bonding of the semiconductor device 16, which is one step of the manufacturing method of the semiconductor device 1 according to the first modification of the second embodiment. The schematic cross-sectional structure of the mounting substrate 8 corresponding to FIG. 10A is expressed as shown in FIG.

  Further, a schematic cross-sectional structure showing a state before the flip chip bonding of the semiconductor device 16 in one step of the method of manufacturing the semiconductor device 1 according to the second modification of the second embodiment is shown in FIG. The schematic cross-sectional structure of the mounting substrate 8 corresponding to FIG. 11A is expressed as shown in FIG.

  As shown in FIGS. 9 to 11, the method for manufacturing a semiconductor device according to the second embodiment includes a step of forming a signal wiring electrode 12 on the mounting substrate 8, and a power wiring electrode penetrating the mounting substrate 8. Forming a semiconductor device 16 having a gate pad electrode GP electrically connectable to the signal wiring electrode 12 and a source pad electrode SP electrically connectable to the power wiring electrode 6; A step of forming the first metal particle bonding layer 18G on one or both of the signal wiring electrode 12 and the gate pad electrode GP and a second metal particle bonding layer 18S on one or both of the power wiring electrode 6 and the source pad electrode SP. And a step of flip-chip connecting the semiconductor device 16 to the mounting substrate 8.

  Further, in the method of manufacturing the semiconductor device according to the second embodiment, the step of forming the first metal particle bonding layer 18G includes the step of forming the paste layer 18 containing conductive particles on either the signal wiring electrode 12 or the gate pad electrode GP. Alternatively, the step of forming the second metal particle bonding layer 18S includes a step of applying the paste layer 18 containing conductive particles to one or both of the power wiring electrode 6 and the source pad electrode SP. Have.

  In the method of manufacturing a semiconductor device according to the second embodiment, the step of flip-chip connecting the semiconductor device 16 to the mounting substrate 8 includes connecting the signal wiring electrode 12 and the gate pad electrode GP via the paste layer 18. In the contact state, the paste layer 18 is baked at a predetermined temperature to join the signal wiring electrode 12 and the gate pad electrode GP, and the power wiring electrode 6 and the source pad electrode SP through the paste layer 18. And the paste layer 18 is baked at a predetermined temperature in the contact state, and the power wiring electrode 6 and the source pad electrode SP are joined.

  In the second embodiment, as shown in FIG. 9, metal particle bonding layers 18G and 18S are arranged on the mounting substrate 8 side. More specifically, the metal particle bonding layer 18 </ b> S is provided on the surface of the power wiring electrode 13, and the metal particle bonding layer 18 </ b> G is disposed on the surface of the signal wiring electrode 12.

  In Modification 1 of the second embodiment, as shown in FIG. 10, metal particle bonding layers 18G and 18S are arranged on the semiconductor device 16 side. More specifically, the metal particle bonding layer 18S is disposed on the source pad electrode SP, and the metal particle bonding layer 18G is disposed on the gate pad electrode GP.

  In Modification 2 of the second embodiment, as shown in FIG. 11, metal particle bonding layers 18G1, 18G2, 18S1, and 18S2 are arranged on both sides of the semiconductor device 16 and the mounting substrate 8, respectively. More specifically, the metal particle bonding layer 18S1 is disposed on the source pad electrode SP, the metal particle bonding layer 18G1 is disposed on the gate pad electrode GP, and the metal particle bonding layer 18S2 is disposed on the power wiring electrode 6. The metal particle bonding layer 18G2 is disposed on the signal wiring electrode 12. In consideration of the thickness of the metal particle bonding layer formed by firing with 18G1 and 18G2 and 18G2 and 18S1 being in close contact, the thickness of 18G1, 18G2, 18S1 and 18S2 is about 5 to 25 μm, respectively. It is said.

  In one step of the method of manufacturing the semiconductor device according to the second embodiment, the state before pressurizing the silver nanopaste as the applied metal particle bonding layer is expressed as shown in FIG. The state of the silver nanopaste after pressing is expressed as shown in FIG. Since other explanations are the same as those in the first embodiment, duplicate explanations are omitted.

(Pressurization and heating process)
A schematic cross-sectional structure showing a pressurizing step, which is one step of the method of manufacturing a semiconductor device according to the second embodiment, is expressed as shown in FIG.

  In the second embodiment or the modified examples 1 and 2, as shown in FIG. 12, a semiconductor is mounted on the mounting substrate 8 with the metal particle bonding layers 18G and 18S (the paste layer 18 before heating and pressurization) sandwiched therebetween. The device 16 is aligned and placed in a face-down state, and in that state, the device 16 is set on the press machine 120 (120a, 120b) and pressure is applied in the direction of arrow P.

  The pressure at this time is, for example, about 2 MPa to about 30 MPa. As a result, the paste layer 18 is brought into a state where the metal particles 22 are in close contact as shown in FIG. 13B from the state shown in FIG.

  In the pressurization step, since the pressurization and heating are performed simultaneously, the entire semiconductor device is heated at 200 to 400 ° C. for a predetermined time by a predetermined baking apparatus or the like (not shown).

  Thereby, the paste layer 18 is baked, and metal silver is deposited to form the metal particle bonding layers 18G and 18S.

  The metal particle bonding layers 18G and 18S made of metallic silver firmly bond the gate pad electrode GP and the signal wiring electrode 12 and the source pad electrode SP and the power wiring electrode 13 to form a semiconductor device on the mounting substrate 8. 16 is electrically joined in a face-down state.

  According to 2nd Embodiment and its modifications 1-2, the semiconductor device which has high heat resistance at low cost, and its manufacturing method can be provided.

(Application examples using semiconductor devices)
Next, a three-phase inverter configured using the semiconductor device 1 according to the first and second embodiments will be described with reference to FIG.

  As shown in FIG. 14, the three-phase inverter includes a gate drive unit 50, a power module unit 52 connected to the gate drive unit 50, and a three-phase motor unit 54. The power module unit 52 is connected to U, V, and W phase inverters corresponding to the U phase, V phase, and W phase of the three-phase motor unit 54.

  In the power module 52, the inverter-structured SiC MOSFETs Q1 and Q2, Q3 and Q4, and Q5 and Q6 are connected between the plus terminal (+) and the minus terminal (−) to which the capacitor C is connected. Furthermore, diodes D1 to D6 are connected in antiparallel between the sources and drains of the SiC MOSFETs Q1 to Q6, respectively.

  As described above, the SiC MOSFETs Q1 to Q6 corresponding to the semiconductor device 16 applied to the semiconductor device 1 according to the first to second embodiments are mounted on the mounting substrate 8 via the metal particle bonding layers 18S and 18G. Electrically connected to the flip chip configuration above.

(Configuration example of semiconductor device)
As an example of the semiconductor device 16 applied to the semiconductor device 1 according to the first to second embodiments, a schematic cross-sectional structure of SiC • MOSFET is a semiconductor substrate made of an n ⁻ high resistance layer as shown in FIG. 26, a p base region 28 formed on the surface side of the semiconductor substrate 26, a source region 30 formed on the surface of the p base region 28, and the surface of the semiconductor substrate 26 between the p base regions 28. Gate insulating film 32, gate electrode 38 disposed on gate insulating film 32, source electrode 34 connected to source region 30, and n ⁺ drain region disposed on the back surface opposite to the surface of semiconductor substrate 26 24 and a drain electrode 36 connected to the n ⁺ drain region 24.

  In FIG. 15, the semiconductor device 16 is configured by a planar gate type n-channel vertical SiC • MOSFET, but may be configured by a trench gate type n-channel vertical SiC • MOSFET.

  Further, a GaN-based FET or the like can be applied to the semiconductor device 16 applied to the semiconductor device 1 according to the first to second embodiments instead of the SiC • MOSFET.

  Furthermore, the semiconductor device 16 applied to the semiconductor device 1 according to the first to second embodiments can use a semiconductor having a band gap energy of, for example, 1.1 eV to 8 eV.

  According to the semiconductor device according to the first to second embodiments, as the metal particle bonding layers 18G and 18S formed by firing the metal particle paste layer, for example, the melting point of metal silver is as high as about 960 ° C. Since the metal particle bonding layers 18G and 18S are applied to power devices such as SiC FETs and GaN FETs, the power devices can be driven at high temperatures.

  FIG. 16 shows an example of the semiconductor device 16 applied according to the first and second embodiments, and a schematic cross-sectional structure of the SiC MOSFET including the source pad electrode SP and the gate pad electrode GP is as shown in FIG. expressed. The gate pad electrode GP is connected to the gate electrode 38 disposed on the gate insulating film 32, and the source pad electrode SP is connected to the source electrode 34 connected to the source region 30.

  Further, as shown in FIG. 16, the gate pad electrode GP and the source pad electrode SP are disposed on an interlayer insulating film 44 for passivation covering the surface of the semiconductor device 16. In the semiconductor substrate 26 below the gate pad electrode GP and the source pad electrode SP, although not shown in the configuration example of FIG. 16, as in the central portion of FIG. 15 or FIG. A transistor structure having a structure may be formed.

  Further, although not shown in the configuration example of FIG. 16, the source pad electrode SP or the gate pad electrode GP extends on the passivation interlayer insulating film 44 also in the central transistor structure of FIG. May be arranged.

  Further, at the time of mounting, the semiconductor device 16 is faced down, and the gate pad electrode GP and the source pad electrode SP are bonded to the mounting substrate 8 via the metal particle bonding layers 18G and 18S, respectively, as shown in FIG. Is done.

(Paste layer application process)
A schematic planar pattern configuration showing a state in which a mask 25 for applying a paste layer 18 on a semiconductor substrate 26 is disposed in a process of the semiconductor device manufacturing method according to the first to second embodiments. 17A, a schematic cross-sectional structure taken along line III-III in FIG. 17A is represented as shown in FIG. 17B.

  FIG. 18 shows a schematic cross-sectional structure showing a state where the paste layer 18 is deposited on the mask 25 having the opening 25a, which is one step of the method for manufacturing the semiconductor device according to the first to second embodiments. Represented as shown.

  Schematic showing one step of the method of manufacturing a semiconductor device according to the first to second embodiments, the step of filling the paste layer 18 into the opening 25a of the mask 25 by moving the squeegee 27 in the direction of arrow A. A typical cross-sectional structure is expressed as shown in FIG.

  A schematic cross-sectional structure showing a state in which the paste layer 18 is filled in the opening 25a of the mask 25, which is one step of the method for manufacturing the semiconductor device according to the first to second embodiments, is shown in FIG. It is expressed as follows.

  In the method of manufacturing a semiconductor device according to the first to second embodiments, the step of applying the paste layer 18 to one of the signal wiring electrode 12 or the gate pad electrode GP is performed by either one of the signal wiring electrode 12 or the gate pad electrode GP. In addition, a step of aligning and overlaying a mask 25 having an opening 25a in accordance with each electrode position, a step of depositing the paste layer 18 on the mask 25, and a squeegee 27, the paste layer 18 is placed on the opening 25a. A step of filling and a step of removing the mask 25.

  In the method for manufacturing a semiconductor device according to the first to second embodiments, the step of applying the paste layer 18 to one of the power wiring electrodes 6 and 13 or the source pad electrode SP includes the power wiring electrodes 6 and 13 or A step of aligning and superimposing a mask 25 having an opening 25 a that matches each electrode position on one of the source pad electrodes SP, a step of depositing a paste layer 18 on the mask 25, and a paste layer by a squeegee 27 18 and filling the opening 25a, and removing the mask 25.

  Hereinafter, the paste layer application step will be described in detail.

  (A) First, as shown in FIGS. 17A and 17B, a mask (for example, a metal mask) 25 is overlaid on a portion of the semiconductor device 16 including the gate pad electrode GP and the source pad electrode SP. In addition, only predetermined regions of the gate pad electrode GP and the source pad electrode SP are exposed through the opening 25a of the mask 25. The distance from the surface of the gate pad electrode GP and the source pad electrode SP to the surface of the mask 25 is equal to the thickness of the paste layer 18 to be formed, for example, about 10 μm to about 100 μm. The thickness is set.

  (B) Next, as shown in FIG. 18, a paste layer 18 made of a predetermined amount of metal fine particle paste is deposited on the mask 25 and the opening 25a using a capillary or a dispenser.

  (C) Next, as shown in FIG. 19, the tip of the squeegee (spatial member) 27 is brought into contact with the surface of the mask 25 and moved in the direction of arrow A (from the left side to the right side in FIG. 19). The paste layer 18 is removed and the paste layer 18 is filled into the opening 25 a of the mask 25.

  As a result, as shown in FIG. 20, the paste layers 18 are formed on the gate pad electrode GP and the source pad electrode SP along the inner wall of the opening 25a of the mask 25, respectively.

  Then, after that, the mask 25 is removed from the semiconductor device 16 side, the semiconductor device 16 is brought into a face-down state, and the process proceeds to a bonding step with the mounting substrate 8 (see FIG. 4 or FIG. 10).

  Depending on properties such as the viscosity of the paste layer 18, it may be preferable to dry the paste layer 18 for a predetermined time in the state shown in FIG. 20 and remove the mask 25 after the paste layer 18 is in a semi-dry state. In this drying step, natural drying may be performed, or the heating and heating step may be performed at a predetermined temperature.

  In the example of FIGS. 17 to 20, the process of applying the paste layer 18 on the semiconductor device 16 side has been described. However, the signal wiring electrode 12 on the mounting substrate 8 and the power wiring electrodes 13 and 6 are mounted by the same method. The paste layer 18 can also be formed on (see FIG. 3B or FIG. 9B).

  Also, as shown in FIG. 5 or FIG. 11, the paste layer 18 is formed on both the semiconductor device 16 side and the mounting substrate 8 side by the same method, and 18G1 and 18G2 and 18S1 and 18S2 are bonded to face each other. You can also. At this time, at least one of the 18G1 and 18G2 sides and the 18S1 and 18S2 sides can be bonded better if they are dried for a predetermined time to be in a semi-dry state.

  According to 2nd Embodiment and its modifications 1-2, the wireless joining provided with high heat resistance can be formed by the simple process of apply | coating and baking a metal fine particle paste.

  Moreover, according to 2nd Embodiment and its modifications 1-2, by forming a joining layer with the metal which is a sintered compact of metal fine particle paste, the heat resistance of the metal particle joining layer, thermal conductivity, etc. A semiconductor device suitable for semiconductor devices such as SiC-based FETs and GaN-based FETs can be provided.

  Further, according to the second embodiment and the first and second modifications thereof, the metal bonding layer is formed of silver, gold, copper or nickel and does not use lead (Pb). Can help.

  According to the second embodiment and the first and second modifications thereof, it is possible to provide a semiconductor device having a high heat-resistant wireless junction at low cost and a method for manufacturing the same.

  In addition, according to the second embodiment and the first and second modifications thereof, since the power wiring electrode disposed through the mounting substrate is provided, a semiconductor device having a larger current than that of the first embodiment. Can be mounted on a mounting board.

  Furthermore, in the semiconductor device according to the first to second embodiments, as shown in FIGS. 21 to 22, the columnar electrode 4 is disposed on the drain electrode 36 via a drain electrode bonding layer 36 a such as solder. May be. For the columnar electrode 4, for example, a metal material having a linear expansion coefficient relatively close to SiC such as copper molybdenum (CuMo) is selected. The drain electrode bonding layer 36a may be formed by baking a paste material containing conductive particles similar to the metal particle bonding layers 18S and 18G. The firing temperature of the paste material is, for example, about 200 to 400 ° C. The conductive particles are metal fine particles, such as silver particles, gold particles, nickel or copper particles.

  A heat spreader 2 is further disposed on the columnar electrode 4. Furthermore, by disposing a heat spreader on which the mounting substrate 8 is mounted, double-sided cooling can be performed in the semiconductor devices according to the first and second embodiments.

[Comparative example]
A comparative example will be briefly described with reference to FIGS.

  In the comparative example shown in FIG. 23, the columnar electrode 180 is formed on the source pad electrode SP of the semiconductor device 140 formed on the insulating substrate 100, and the gate pad electrode GP is interposed via the bridge-shaped lead member 160. The structure which aimed at joining with the wiring part 125 is shown.

  This configuration has the advantage that the conventional wire bonding need not be performed, but has the problem that the lead member 160 itself is a fine component and is difficult to mount.

  Further, since the lead member 160 itself is relatively expensive, there is a disadvantage that the cost increases.

  Further, when there is a difference in height between the semiconductor device 140 side and the wiring part 125 side, the end of the lead member 160 is lifted as shown in FIG. is there.

  In the comparative example shown in FIG. 22, the columnar electrode 180 is formed on the source pad electrode SP of the semiconductor device 140 formed on the insulating substrate 100, and the silver nanopaste sintered body 18 </ b> A is used for the gate pad electrode GP. The structure which aimed at joining with the wiring part 125 via this is shown.

  This configuration has the advantage that conventional wire bonding does not have to be performed, and wiring components need not be used as in the comparative example of FIG.

  However, there is a problem that it is difficult to ensure the insulating properties of the side surfaces of the silver nanopaste sintered body 18A and the semiconductor device 140 and the lower side of the silver nanopaste sintered body 18A.

  In the comparative example shown in FIG. 25, the columnar electrode 180 is formed on the source pad electrode SP of the semiconductor device 140 formed on the insulating substrate 100, and the columnar electrode 200 is formed on the gate pad electrode GP. In addition, a configuration in which a mounting substrate (not shown) or the like facing the insulating substrate 100 through the upper end face of the columnar electrode 200 is intended to be joined.

  However, there is a problem that a finely processed columnar electrode is necessary, and it is difficult to form a columnar electrode having a size of about 500 μm square or less.

  Further, when the columnar electrode is used, it is limited to the wiring in the vertical direction, and there is a disadvantage that it cannot be applied to the wiring in the horizontal direction.

  In addition, when the upper end surfaces of the columnar electrode 180 and the columnar electrode 200 are bonded to the mounting substrate through solder, it is difficult to apply the high heat-resistant bonding technique, and it is compatible with high-temperature operation of SiC devices and the like. There is also the inconvenience that it cannot be done.

  According to the present embodiment, it is possible to provide a mounting structure of a semiconductor device having high heat resistance at low cost.

  Further, according to the present embodiment, it is possible to provide a semiconductor device mounting method capable of performing wireless bonding having high heat resistance by a simple process.

[Other embodiments]
As described above, the embodiments and modifications have been described. However, the descriptions and drawings forming a part of this disclosure are illustrative and should not be understood as limiting the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  As described above, the present invention includes various embodiments not described herein.

  For example, in the above embodiment, the case where silver nanopaste is used as a paste material containing conductive particles has been described. However, the present invention is not limited to this, and metal nanoparticles in which gold nanoparticles or nickel nanoparticles are dispersed in a predetermined solvent are described. A particle paste may be used.

The method for manufacturing a semiconductor device of the present invention can be used for power devices in general such as a power semiconductor module and an intelligent power module.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device 2 ... Heat spreader 4 ... Columnar electrode 6, 13 ... Power wiring electrode 8 ... Mounting board 12 ... Signal wiring electrode 16 ... Semiconductor device 18 ... Paste layer 18G, 18S ... Metal particle joining layer 19 ... Silver plating layer 20 ... Solvent 20a ... Shell 22 ... Silver nanoparticles 24 ... n ⁺ drain region 25 ... Mask 25a ... Opening 26 ... Semiconductor substrate 27 ... Squeegee (scalar member)
28 ... p base region 30 ... source region 32 ... gate insulating film 34 ... source electrode 36 ... drain electrode 36a ... drain electrode bonding layer 38 ... gate electrode 44 ... interlayer insulating film 50 ... gate drive part 52 ... power module part 54 ... three Phase motor 120 ... Press machine C ... Capacitors D1-D6 ... Diode GP ... Gate pad electrode SP ... Source pad electrode

Claims (9)

  Forming a signal wiring electrode on the mounting substrate;
  Forming a power wiring electrode on the mounting substrate or penetrating the mounting substrate;
  Disposing a power device having a gate pad electrode electrically connectable to the signal wiring electrode and a source pad electrode electrically connectable to the power wiring electrode;
  Applying a first paste layer including a plurality of first metal fine particles and a first antioxidant film covering the plurality of first metal fine particles to one or both of the signal wiring electrode and the gate pad electrode;
  Applying a second paste layer including a plurality of second metal fine particles and a second antioxidant film covering the plurality of second metal fine particles to one or both of the power wiring electrode and the source pad electrode;
  Flip chip connecting the power device onto the mounting substrate;
  Have
  The step of flip-chip connecting the power device on the mounting substrate,
    The signal wiring electrode and the gate pad electrode are brought into contact with each other through the first paste layer, and in the contact state, the mounting substrate and the power device are pressed in a facing direction to the first paste layer. A predetermined pressure is applied to bring the plurality of first metal fine particles into close contact with each other on the surface where the first antioxidant film is crushed, and the first paste layer is baked at a predetermined temperature, and the signal wiring electrode and the gate A step of pressure bonding the pad electrode;
    The power wiring electrode and the source pad electrode are brought into contact with each other through the second paste layer, and in the contact state, the mounting substrate and the power device are pressed in a facing direction, and the second paste layer is pressed. A predetermined pressure is applied to bring the plurality of second metal fine particles into close contact with each other on the surface where the second antioxidant film is crushed, and the second paste layer is baked at a predetermined temperature, and the power wiring electrode and the source And a step of pressure bonding the pad electrode.   The step of applying the second paste layer to one or both of the power wiring electrode and the source pad electrode,
  A step of aligning and overlaying a mask having an opening corresponding to each electrode position on one or both of the power wiring electrode or the source pad electrode;
  Depositing the second paste layer on the mask;
  Filling the opening with the second paste layer with a squeegee;
  Removing the mask;
  The method of manufacturing a semiconductor device according to claim 1, wherein:   The method of manufacturing a semiconductor device according to claim 1, wherein the predetermined pressure is 2 to 30 MPa.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the first paste layer and the second paste layer are silver nano pastes in which silver nanoparticles are dispersed in a predetermined solvent.   The method of manufacturing a semiconductor device according to claim 4, wherein the silver nanopaste has a concentration of the silver nanoparticles of 80% by mass to 95% by mass.   6. The method of manufacturing a semiconductor device according to claim 4, wherein the silver nanopaste has a silver nanoparticle diameter of 30 nm to 100 nm.   The method for manufacturing a semiconductor device according to any one of claims 4 to 6, wherein a baking temperature of the silver nanopaste is 200 ° C to 400 ° C.   The method of manufacturing a semiconductor device according to claim 1, wherein the power device is a SiC-based FET or a GaN-based FET.   The power device includes a drain electrode disposed on a surface opposite to a surface on which the gate pad electrode and the source pad electrode are disposed,
  The method of manufacturing a semiconductor device according to claim 1, further comprising a step of disposing a heat spreader on the drain electrode via a columnar electrode.

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