JP2017162973A - High-frequency semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency semiconductor device which ensures high reliability by following a warpage shape of a frame surface to be bonded with a lid part to achieve high hermetic bonding.SOLUTION: A high-frequency semiconductor device has a package base, a metal lid part, a first bond layer and a high-frequency semiconductor element. The first bond layer bonds the package base and the lid part; and is formed in a closed curve shape; and composed of a first metal nanoparticle layer. The package base includes a metal plate, a frame having a lead part and a second bond layer. The second bond layer bonds an undersurface of the frame with an outer periphery of a top face of the metal plate; and is formed in a closed curve shape. The high-frequency semiconductor element is bonded to a surface of the metal plate in an internal space between the package base and the lid part. The package base warps toward the frame in a convex cross-sectional shape; and the first metal nanoparticle layer and the lid part are bent along warpage of the convex cross section of the package base.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a high-frequency semiconductor device.

  In order to ensure high reliability, such as a radar device or a communication device in which a high-frequency semiconductor device is mounted, the package is required to be airtight. A semiconductor element such as a HEMT (High Electron Mobility Transistor) that can operate at a frequency higher than a microwave is mounted on a package.

  The package includes a metal plate, a frame with lead terminals, a lid, and the like. Silver brazing material is used for joining the metal plate and the frame because of its high melting point.

  After mounting the components, the frame and the lid are joined and hermetically sealed. Gold-tin solder having a melting point lower than the component mounting temperature is used for joining the ceramic frame and the lid after mounting the components. In order to further lower the bonding temperature, there is a technique using metal nanoparticles as a bonding material.

JP 2011-165745 A

  In order to obtain hermeticity with the metal nanoparticles, it is essential to pressurize all the joint surfaces. However, the surface of the frame that becomes the joint surface may be warped or distorted. A high-frequency semiconductor device in which high reliability is ensured by absorbing the warpage and realizing highly airtight bonding is provided.

   The high-frequency semiconductor device of the embodiment has a package base, a lid made of metal, a first bonding layer, and a high-frequency semiconductor element. The first joining layer joins the package base and the lid, is provided in a closed curve shape, and includes a first metal nanoparticle layer. The package base includes a metal plate, a frame having a lead portion, and a second bonding layer. The second joining layer joins the lower surface of the frame and the outer peripheral portion of the upper surface of the metal plate, and is provided in a closed curve shape. The high-frequency semiconductor element is bonded to the surface of the metal plate in the internal space between the package base and the lid. The package base is warped in a convex cross section toward the frame, and the first metal nanoparticle layer and the lid are bent along the warp of the convex cross section of the package base.

1A is a schematic perspective view of the high-frequency semiconductor device according to the first embodiment, FIG. 1B is a schematic cross-sectional view along the line AA, and FIG. 1C is along the line BB. FIG. FIGS. 2A to 2D are schematic views for explaining the manufacturing process of the package base, FIG. 2A is a perspective view of the ceramic member, and FIG. 2B is a perspective view for explaining the simultaneous firing process of the ceramic. FIG. 2 (c) is a perspective view for explaining a through hole forming process, and FIG. 2 (d) is a perspective view for explaining a joining process of a frame and a metal plate. 3A is a schematic perspective view of a state in which a solder material or the like is bonded to a high frequency semiconductor element and an input / output circuit board on the package base, and FIG. 3B is a schematic view in which the lid 30 and the package base are bonded. FIG. 4 (a) and 4 (b) are schematic views for explaining a process of applying the metal nanoparticle paste to the lid, and FIG. 4 (a) is a cross-sectional view taken along the line CC, FIG. 4 (b). ) Is a plan view. FIGS. 5A to 5F are schematic views for explaining a cross-sectional shape for each manufacturing process according to the first embodiment. FIG. 5A is a diagram in which a metal plate, a silver brazing material, and a frame are stacked. FIG. 5B shows the state after the brazing process, FIG. 5C shows the process after the metal nano paste is applied to the frame, FIG. 5D shows the drying process, and FIG. FIG. 5F is a cross-sectional view for explaining the completed high-frequency semiconductor device after the bonded pressurizing / heating process. 6A to 6F are schematic views for explaining a cross-sectional shape for each manufacturing process of the high-frequency semiconductor device according to the comparative example. FIG. 6A shows a metal plate, a silver brazing material, and a frame. FIG. 6 (b) is after the silver brazing process, FIG. 6 (c) is after the process of applying the metal nano paste on the lid, FIG. 6 (d) is after the drying process, and FIG. FIG. 6F is a cross-sectional view illustrating the completed high-frequency semiconductor device after the pressurizing / heating process. FIGS. 7A to 7E are schematic views for explaining a cross-sectional shape for each manufacturing process of the high-frequency semiconductor device according to the second embodiment, and FIG. 7B is a process for drying the metal nano paste, FIG. 7C is a process for forming the package base, and FIG. 7D is a process for drying the metal nano paste. (E) is sectional drawing explaining after the process which joins a package base and a cover part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A is a schematic perspective view of the high-frequency semiconductor device according to the first embodiment, FIG. 1B is a schematic cross-sectional view along the line AA, and FIG. 1C is along the line BB. FIG.
The high-frequency semiconductor device 10 includes a package base 20, a lid portion 31 made of metal, a first bonding layer 32, a high-frequency semiconductor element 40, and an input / output circuit substrate 42.
The first bonding layer 32 is a metal nanoparticle layer provided in a closed curve shape.

  The package base 20 includes a metal plate (metal base) 22 and a frame body 24 having lead portions. The lower surface 24a of the frame body 24 and the outer peripheral portion 22a of the metal plate 22 are joined by a second joining layer 26 provided in a closed curve shape. The second bonding layer is, for example, silver solder provided in a closed curve shape.

  The first bonding layer 32 is provided in a closed curve shape so as to bond the frame body 24 and the outer peripheral portion 31 a of the lid portion 31.

  For example, the length L1 of one side of the frame 24 and the length L2 of the other side can both be 10 mm, for example. The high-frequency semiconductor element 40 is bonded to the surface of the metal plate 22 in the internal space N between the package base 20 and the lid 31.

  2A to 2D are schematic perspective views for explaining a manufacturing process of the package base. 2A is a schematic diagram of two ceramic members constituting the frame body, FIG. 2B is a schematic diagram illustrating a simultaneous firing process of ceramics, and FIG. 2C is a diagram illustrating a through-hole formation process. FIG. 2D is a schematic diagram for explaining silver brazing on a metal plate (metal base) and a lead portion as a frame.

In the first embodiment, the frame body 24 is made of ceramic. As shown in FIG. 2A, frame-shaped ceramics made of aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), or the like are respectively molded. Further, a conductive portion 25 made of, for example, a thick film is provided in a region where the lead portion 28 is provided. Next, as shown in FIG. 2B, using a carbon mold or the like, the positions of the two frames 24c and 24d are placed in a furnace, and co-fire is performed.

  Next, the two frames 24c and 24d are integrated into a frame 24 by simultaneous firing. A through hole TH penetrating from the upper surface 24b of the frame body 24 to the lower surface 24a is formed (FIG. 2C). A conductive layer is provided on the side surface or inside of the through hole TH to enable conduction from the upper surface 24b to the lower surface 24a. By electrically connecting the metallized portion provided in the lid portion 31 to the metal plate 22 of the package base portion 20 through the conductive portion of the through hole TH, the influence of EMI (Elecro-Magnetic Interference) is reduced or unnecessary. Resonance can be suppressed.

  The thickness T1 of the metal plate 22 may be 0.5 to 1.5 mm, the width W5 of the frame body 24 may be 0.2 to 1.5 mm, and the height T2 of the frame body 24 may be 0.5 to 1 mm. .

  Next, as shown in FIG. 2D, the lower surface 24a of the frame body 24 and the outer peripheral portion 22a of the metal plate 22 are joined by a joining layer 26 provided in a closed curve shape. The bonding layer 26 can be silver solder or the like. When the silver brazing contains silver (72 wt%) and copper (28 wt%), the silver brazing temperature can be 780 to 900 ° C.

  When the brazing temperature is high in this way, the metal plate 22 made of copper or the like having a large linear expansion coefficient warps so as to protrude upward with respect to the ceramic having a small linear expansion coefficient during cooling. The high-frequency semiconductor element 40 can be bonded with a solder material or the like in the bonding region on the surface of the metal plate 22. In this way, the package base 20 is completed. The high-frequency semiconductor element 40 can be bonded to the bonding region on the surface of the metal plate 22 with a gold-tin solder material or an adhesive. When the silver brazing temperature is thus high, the metal plate 22 made of Cu or the like having a large linear expansion coefficient warps so as to protrude upward with respect to the ceramic having a small linear expansion coefficient during cooling.

3A is a schematic perspective view of a state in which the high-frequency semiconductor element 40 and the input / output circuit board 42 are joined to the package base by a solder material or an adhesive, and FIG. 3B is a lid 31 and the package base 20. FIG. 2 is a schematic perspective view in which and are joined by a metal nanoparticle layer.
In the first embodiment, when the high-frequency semiconductor element 40 is a HEMT (High Electron Mobility Transistor), the output can be increased by elongating the chip shape to a multi-cell structure. The high-frequency semiconductor device shown in FIG. 1C can be easily mounted on a microstrip circuit.

  FIGS. 4A and 4B are schematic views for explaining a process of applying a metal nanoparticle paste to the upper surface of the frame 24 of the package base in the first embodiment. FIG. FIG. 4B is a sectional view taken along line C, and FIG. 4B is a plan view.

  The metal nano paste 32 c is supplied from the dispenser 90 to the surface of the lid 30. The dispenser 90 is scanned along the outer peripheral portion 31a of the lid portion 31 and drops the liquid metal nano paste 32c. The metal nano paste 32c can be similarly applied to the upper surface 24b of the frame 24 shown in FIG.

  The metal nano paste 32c is prepared by mixing metal particles such as silver, gold, platinum, and palladium and an organic solvent such as ester alcohol in a desired ratio. The particle size of the metal particles is several tens to several hundreds of nanometers. The ratio of the metal particles is, for example, 85 to 93% by weight. The proportion of the organic solvent is, for example, 5 to 15% by weight. When the heating temperature is 80 to 300 ° C. or the like, a metal nanoparticle layer in which metal particles in the metal nanopaste are sintered is obtained.

The metal plate 22 can be copper, the frame 24 can be ceramic, the bonding material 26 can be silver brazing, and the metal nanoparticle layer 32 can be silver nanoparticle layer.
FIG. 5A to FIG. 5F are schematic views for explaining a cross-sectional shape for each manufacturing process of the first embodiment. 5A shows a state in which a metal plate, a silver brazing material, and a frame are stacked, FIG. 5B shows a silver brazing process, and FIG. 5C shows a process of applying metal nano paste to the frame. 5D is a cross-sectional view illustrating a dry process, FIG. 5E is a pressurizing / heating process with a lid joined, and FIG. 5F is a cross-sectional view illustrating a completed high-frequency semiconductor device.

In FIG. 5A, the metal plate 22 is made of copper, the bonding material 26 is made of silver brazing, and the frame body 24 is made of ceramic. As shown in FIG. 5B, the metal plate 22 and the frame body 24 are joined by heating to about 850 ° C. Since the coefficient of linear expansion of copper (16.5 × 10 ⁻⁶ / K) is larger than the coefficient of linear expansion of ceramic, the package base 20 after cooling is deformed so that the upper surface (ceramic side) has a convex cross section. The This amount of warpage is S3. The warpage amount S3 is 30 to 100 μm or the like.

  As shown in FIG. 5C, the lid 31 is made of a metal such as Kovar. Silver nanopaste 32c is applied to lid 31 using a dispenser or the like. Next, as shown in FIG. 5D, the organic solvent is volatilized by heating to about 120 ° C. At this time, the thickness decreases by about 10%.

  Next, as illustrated in FIG. 5E, the lid portion 31 is placed so that the vicinity of the central convex portion of the frame body 24 made of ceramic and the silver nanoparticle layer 32 are in contact with each other. Pressurize and heat (about 200 ° C). Immediately after the start of pressurization, pressure concentrates in the vicinity of the convex portion. However, when pressurization is performed through a cushioning material such as silicon rubber, the lid portion 31 made of metal is attached to the frame 31 as shown in FIG. Along the warp, the range of joining by pressurization and heating spreads over the entire lid portion 31.

  That is, even if the package base 20 is warped (warp amount S3), the lid portion 31 made of metal is deformed according to the warp, so that airtightness is maintained. In addition, the cover part 31 made of metal may have a convex cross section in a region other than the joint surface with the frame body 24 upward.

  6A to 6F are schematic views illustrating a manufacturing process of a high-frequency semiconductor device according to a comparative example. 6A shows a state in which a metal plate, a silver brazing material, and a frame are stacked, FIG. 6B shows a silver brazing process, and FIG. 6C shows a case where silver nano paste is applied to the lid. FIG. 6D is a cross-sectional view illustrating the high-frequency semiconductor device after the process, FIG. 6D after the drying process, FIG. 6E after the pressurizing / heating process, and FIG. 6F.

  6A, the metal plate 122 is made of copper, the bonding material 126 is made of silver brazing, and the frame body 124 is made of ceramic. These members are superposed and heated to, for example, 850 ° C. Since the linear expansion coefficient of copper is larger than the linear expansion coefficient of ceramic, the package base 120 is warped so as to be convex upward (ceramic side) after cooling (FIG. 6B).

  On the other hand, as shown in FIG. 6C, the silver nano paste 132c is applied to the lid portion 130 made of ceramic. Furthermore, as shown in FIG. 6D, when the organic solvent is volatilized by heating to about 120 ° C., the thickness of the silver nanopaste 132c decreases by about 10%.

  Subsequently, as shown in FIG. 6E, the silver nanopaste 132c of the lid 130 and the frame 124 of the package base 120 are brought into contact with each other and pressurized and heated (about 200 ° C.). Immediately after the start of heating, pressure concentrates in the vicinity of the convex portion of the package base 120. Further, the silver nanoparticles in the pressurized region are crushed and the pressed area increases as the reaction of the silver nanoparticles proceeds, but a region with a large warp produces a region that is not pressed and not joined (FIG. 6 ( f)). For this reason, it becomes difficult to keep the inside of the package airtight, moisture or the like enters from the outside, and the high-frequency semiconductor element 40 is likely to be deteriorated.

  On the other hand, even if the package base 20 used in the present embodiment is warped (warp amount S3), the lid portion 31 made of metal is bent according to the warp of the package base 20 to keep the inside airtight. Becomes easy.

  7A to 7E are schematic views for explaining a method for manufacturing a high-frequency semiconductor device according to the second embodiment. 7A is a process for applying a metal nano paste to a metal plate, FIG. 7B is a process for heating the metal nano paste, FIG. 7C is a process for forming a package base, and FIG. ) Is a process for heating the metal nanopaste, and FIG. 7E is a cross-sectional view for explaining a process for joining the package base and the lid.

  When the silver nano paste 33c is applied to the metal plate 22 as shown in FIG. 7 (a) and further heated to about 120 ° C. as shown in FIG. 7 (b), the organic solvent evaporates from the silver nano paste 33c and the thickness is increased. Is reduced by about 10% to form a silver nanoparticle layer 33. As shown in FIG. 7C, when the frame body 24 made of ceramic (for example, aluminum oxide) is stacked and pressed and heated (about 200 ° C.), the silver nanoparticle layer 33 forms the metal plate 22 and the frame body 24. The package base 20 is joined.

The linear expansion coefficient of copper is larger than that of aluminum oxide (approximately 6.4 × 10 ⁻⁶ / K). However, since the heating temperature is about 200 ° C., which is lower than the heating temperature of silver solder (about 850 ° C.), the warp after cooling (the frame 24 side is slightly convex) is sufficiently small.

  That is, the warp of the package base 20 of the second embodiment is sufficiently smaller than the warp (warp amount S3) of the package base 20 of the first embodiment. Subsequently, as shown in FIG. 7D, the silver nano paste 32 c is applied to the upper surface of the frame body 24 of the package base 20 and heated to about 120 ° C. By heating, the thickness of the silver nanoparticle layer 32 is reduced by about 10%.

  Further, as shown in FIG. 7E, a lid portion 31 made of metal is placed on the silver nanoparticle layer 32 and heated (about 200 ° C.) while being pressurized through silicon rubber or the like. The metal nanoparticle layer 32 and the lid portion 31 warp along the convex cross section of the package base 20. For this reason, the high-frequency semiconductor element is kept airtight in the package.

  According to the first and second embodiments, a high-frequency semiconductor device in which the high-frequency semiconductor element is suppressed from being deteriorated by moisture or the like is provided. Radar devices and satellite communication devices equipped with such high-frequency semiconductor devices can maintain high reliability even in harsh usage environments.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 High frequency semiconductor device, 20 Package base, 22 Metal plate, 22a Outer peripheral part, 24 Frame body, 24a Bottom surface of frame body, 24b Upper surface of frame body, 26 Bonding material, 31 Lid part, 32, 33 Metal nanoparticle layer, 32c 33c Metal nano paste, S3 Warpage amount

Claims (5)

A package base;
A lid made of metal;
Bonding the package base and the lid, a first bonding layer provided in a closed curve shape and comprising a first metal nanoparticle layer;
A high-frequency semiconductor element;
With
The package base includes a metal plate, a frame body having a lead portion, and a second bonding layer,
The second joining layer joins the lower surface of the frame and the outer peripheral portion of the upper surface of the metal plate, and is provided in a closed curve shape.
The high-frequency semiconductor element is bonded to the surface of the metal plate in the internal space of the package base and the lid,
The package base is warped in a convex cross-section toward the frame, and the first metal nanoparticle layer and the lid are bent along the warp of the convex cross-section of the package base. .   The high-frequency semiconductor device according to claim 1, wherein the frame is ceramic, and the metal plate is copper.   The high-frequency semiconductor device according to claim 1, wherein the second bonding layer is silver solder.   The high-frequency semiconductor device according to claim 1, wherein the second bonding layer is a second metal nanoparticle layer.   The high-frequency semiconductor device according to claim 4, wherein the first and second metal nanoparticle layers contain silver.

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