JP4641286B2 - Semiconductor package - Google Patents

Description

  The present invention relates to a high frequency semiconductor device, and more particularly to a semiconductor package in which a millimeter wave semiconductor device is mounted.

  High-frequency semiconductor devices such as millimeter-wave radar semiconductor devices are packaged from the viewpoints of environmental resistance, operational stability, cost reduction, size reduction, and the like.

  However, when the size of the cavity in the package is an integral multiple of 1/2 of the in-tube wavelength of the electromagnetic wave propagating through the cavity, resonance occurs and a standing wave is formed inside. In a semiconductor package on which a high-frequency semiconductor device is mounted, it is difficult to reduce the size of the cavity to ½ or less of the in-tube wavelength in the cavity, and there is a high possibility that resonance will occur. Standing waves excite devices and wire bonds in the package, causing unstable operation and unnecessary propagation. Therefore, the isolation between the transmission and reception ports is deteriorated and the isolation between the reception ports is deteriorated.

  In order to solve this problem, Patent Document 1 discloses a semiconductor package having a structure in which prismatic protrusions are periodically arranged in a lattice or checkered pattern. Patent Document 2 shows a structure in which prismatic or columnar protrusions are arranged in a grid pattern, and describes that these structures are manufactured by press working. Patent Document 3 shows a structure in which conical and elliptical columnar protrusions are periodically arranged. Patent Document 4 discloses a semiconductor package having a structure in which slits are periodically arranged.

In addition, Non-Patent Document 1 is one that uses a periodic structure. This document shows a delay line technique using a periodic structure, and further suggests that the periodic structure can form a band gap.
Japanese Patent No. 3739230 Japanese Patent No. 3589137 JP-A-11-40689 JP 2006-73935 A Mitsuo Kawamura, Microwave Fundamental Engineering, Shosodo, pp. 113-126

  As described above, since the package is preferably small and low-cost, it is desirable that the periodic structure can be easily manufactured and the period is short or the number of repetitions of the periodic structure is small.

  However, in the periodic structures described in Patent Literatures 1, 2, and 3, the effect of preventing propagation of electromagnetic waves per cycle is not so high, and the number of repetitions increases, resulting in a large package. Further, in the periodic structure described in Patent Document 4, the period is the same as the guide wavelength, which is larger than ½ of the guide wavelength, which is the period of the periodic structure described in Patent Documents 1 and 2. I have to enlarge the package. Moreover, the slit of patent document 4 describes that it produces using a laser processing machine etc., and is not desirable also from a viewpoint of the ease of manufacture.

  Therefore, the present invention provides a semiconductor package having a periodic structure that has a higher electromagnetic wave shielding effect than a conventional periodic structure and can be easily manufactured.

A first invention is a rectangular parallelepiped semiconductor package comprising a substrate on which a millimeter-wave semiconductor device is installed and a conductive lid that covers and seals the substrate , and is provided facing each other in the first axial direction, A first port that inputs or outputs, a second port, a third port that is provided opposite to each other in a second axis direction orthogonal to the first axis, and that inputs or outputs electromagnetic waves, a fourth port, and a semiconductor package The traveling direction of the electromagnetic wave propagating in the semiconductor package is input / output to / from the first port and the second port on the upper surface inside the lid in the first region that bisects A first periodic structure composed of a plurality of conductive plates perpendicular to one axis and periodically arranged along the first axis, and a second region different from the first region that bisects the semiconductor package; the inside of the lid The upper surface, is erected toward the substrate side, the third port, and input to and output from the fourth port, perpendicular to the second axis which is the traveling direction of the electromagnetic wave propagating in the semiconductor package, and, the second axis A second periodic structure comprising a plurality of conductive plates periodically arranged along the first and second periodic structures, wherein the first periodic structure and the second periodic structure are arranged directions of the plates of the respective periodic structures Are arranged in a T-shape, and the interval between the plates is 1/2 × 0.8 to 1/2 × 1.2 of the in-tube wavelength of the propagating electromagnetic wave, and the height of the plates is The semiconductor package is characterized in that the wavelength within the tube of the electromagnetic wave is ¼ × 0.8 to ¼ × 1.2 , and the distance between the plate and the substrate is 1.0 mm or less .

Along the traveling direction of the electromagnetic wave means that the traveling direction of the electromagnetic wave is in line with the arrangement direction of the plates, and that the traveling direction of the plates and the traveling direction of the electromagnetic waves are not orthogonal, that is, each It means that the traveling direction of electromagnetic waves is not parallel to the plate. In this case, the angle formed by the plate and the traveling direction of the electromagnetic wave is preferably as close to a right angle as possible, and most preferably a right angle. Further, the interval between the plates is more preferably 1/2 × 0.9 to 1/2 × 1.1 of the guide wavelength, and more preferably 1/2 of the guide wavelength. The height of the plate is also preferably 1/4 × 0.9 to 1/4 × 1.1 of the guide wavelength, and more preferably 1/4 of the guide wavelength.
The conductive lid and plate may be metal, or may be formed by plating a material other than metal. For example, as the metal, aluminum or the like can be used, and in addition to the metal, a resin or the like subjected to metal plating can be used. The metal used for plating can be gold. Further, the entire lid does not need to be conductive, and the inner surface of the lid or the inside of the wall of the lid may be conductive. Further, the lid and the plate may be integrated.

In the present invention, the plate is arranged perpendicular to the line connecting the input / output ports installed on the substrate . In this case, so that the plate is perpendicular to the electromagnetic wave propagating between the input and output ports.

In the present invention, there are a plurality of traveling directions of electromagnetic waves propagating in the semiconductor package, and a plate is arranged along each traveling direction on the upper surface of the lid, and is composed of a plurality of array portions for each traveling direction . .

  When there are multiple input / output ports, there are multiple directions of electromagnetic wave travel, and if only plates are arranged in a specific direction, even if plates are arranged along the direction of electromagnetic wave travel between other input / output ports, There is a case where the traveling direction of the electromagnetic wave does not follow the arrangement direction of the plates between the output ports, and the propagation suppressing effect is remarkably reduced particularly when they are parallel.

In the present invention, several regions are divided for each traveling direction of the electromagnetic wave, and the plates are arranged along the traveling direction of the electromagnetic wave in the region. That is, the upper surface inside the lid is constituted by a periodic structure of several plates having different arrangement directions. Further, at the boundary of the region, the plate and the plate intersect with each other due to the difference in the arrangement direction of the plates. By such a structure, the part which does not follow the advancing direction of electromagnetic waves is reduced.

In the invention, the high frequency semiconductor device is a millimeter wave semiconductor device . Since the package can be reduced in size, the package of the present invention is particularly effective for a package on which a millimeter wave semiconductor is mounted.

Each of the second to fourth inventions is a structure characterized by the formation of a periodic structure.
The periodic structure according to the present invention can be easily formed by press molding, resin molding, or integral molding by aluminum die casting. In the case of resin molding, the surface after molding is subjected to metal plating.

  The thinner the plate is, the higher the effect of suppressing the propagation is. Therefore, in order to process, at least 300 micrometers or more are required, and the thinner one is good. Further, by adjusting the distance between the plate and the substrate, the thickness of the plate can be increased to some extent while maintaining the same propagation suppression effect.

  Gold or the like can be used as a metal used when pressing a metal plate or when plating the surface after resin molding.

As in the invention , the periodic structure is produced with the plate on the inner upper surface of the lid, so that in the package, a band gap is formed in the in-tube wavelength band of the electromagnetic wave propagating in the package. Propagation can be suppressed. Therefore, resonance in the package can be prevented, and deterioration of isolation between input and output ports can be prevented. In addition, since the structure is simple, manufacturing is easy and cost reduction is possible. In addition, when the traveling direction of the electromagnetic wave is orthogonal to the plate, the effect of suppressing the propagation of electromagnetic wave is the highest, so that the number of plates having a periodic structure can be reduced, and the package can be further downsized. Also, in the structure of the inventions, it can not be suppressed completely the propagation of electromagnetic waves, standing waves are generated in the package, a strong part of the electric field is generated. However, by adjusting the region, it is possible to prevent a portion where the electric field is strong from coming on a semiconductor device or a line that is easily affected by the electric field. Therefore, it is possible to prevent deterioration of isolation between ports.

  Hereinafter, the present invention will be described based on specific examples. However, the present invention is not limited to the following examples.

  In Example 1, a package having a periodic structure according to the present invention was manufactured, and it was confirmed whether propagation of electromagnetic waves of a specific wavelength could be effectively suppressed in the package. In consideration of applying the package of the present invention to a millimeter-wave semiconductor, the guide wavelength to be suppressed was set to 4.6 mm. The package structure of the first embodiment will be described in detail below.

  1 is a perspective view of a package of Example 1. FIG. It is shown in a transparent manner so that the structure inside the package can be understood. For ease of explanation, the x, y, and z axes are shown in FIG. 1 for convenience. FIG. 2 is a cross-sectional view of the package along the x-axis. The package is a rectangular parallelepiped, and the x-axis is selected so that the package is symmetrical with respect to the x-axis. The package includes a substrate 10 having an input port 12 and an output port 13, and a conductive lid 11 that covers the substrate 10 and seals the package. Inside the lid 11, conductive plates 14 a to 14 f are installed in parallel to the side surfaces 15 a and b (y-axis direction) of the lid 11. The distance D1 between the plates 14a to 14f is 2.3 mm which is ½ of the in-tube wavelength of the electromagnetic wave propagating in the package, and the distance D2 between the plates 14a and the side surface 15a and the plate 14f and the side surface 15b is about ¼ of the in-tube wavelength. 1.1 mm, the height D3 of the plates 14a to 14f is 1.3 mm, which is slightly larger than ¼ of the guide wavelength, the thickness D4 of the plates 14a to 14f is 0.3 mm, and the distance D5 between the substrate 10 and the plates 14a to 14f Is 0.6 mm. Further, the input port 12 and the output port 13 are on the x axis, and the chip 16 is installed on the substrate 10. The line 17 connecting the chip 17 and the input port 12 and the line connecting the chip 17 and the output port 13. The input port 12 is installed between the plates 14a and 14b, and the output port 13 is installed between the plates 14e and 14f. Since the input port 12 and the output port 13 are thus installed, the space between the input port 12 and the output port 13 is orthogonal to the plates 14a to 14f.

  The periodic structure by the plates 14a to 14f was produced by pressing a metal plate. Since it has a simple structure, it can be easily manufactured. Further, the plate-like periodic structure may be formed by applying metal plating to a resin-molded one, or may be formed by aluminum die casting. Similar effects can be obtained.

  When an electromagnetic wave of 77 GHz was incident from the input port 12 of the package of Example 1 and the electric field distribution in the package was examined, the results of FIGS. 3 and 4 were obtained. FIG. 3 shows the electric field distribution in the plane where z = D5, and the whiter the color, the stronger the electric field. FIG. 4 shows the electric field distribution in the same cross section as FIG. As in FIG. 3, the whiter the color, the stronger the electric field. It can be seen that the electric field is strong near the input, but gradually weakens and hardly propagates to the output port 13. Further, the propagation can be most effectively suppressed in the x-axis direction, that is, the direction orthogonal to the plates 14a to 14f, and there is almost no suppression effect in the y-axis direction, that is, the direction parallel to the plates 14a to 14f. I understand.

  3 and 4, it can be seen that the number of plates is sufficient to prevent propagation when the number of plates is 4 or 5, and that a periodic structure of about 4 or 5 cycles is highly effective. Therefore, in the package of Example 1, it is considered possible to further reduce the size of the package.

Here, a qualitative explanation that the band gap is formed at a specific wavelength due to the periodic structure will be described with reference to FIG.
As shown in FIG. 5, when the electromagnetic wave travels to the right in the region sandwiched between the upper and lower conductors, the electric field is downward and the magnetic field is downward perpendicular to the drawing. However, since there is a barrier, the electric field is bent as shown in FIG. 5, and a component parallel to the traveling direction of the electromagnetic wave is generated. Therefore, an electromagnetic wave propagating along the barrier is generated, and a standing wave is formed because the height of the barrier is ¼ of the in-tube wavelength of the electromagnetic wave. That is, part of the energy of the electromagnetic wave is converted into the energy of the electromagnetic wave perpendicular to the traveling direction, and the energy in the traveling direction decreases. Further, if there is a barrier at a distance of ½ of the in-tube wavelength of the electromagnetic wave, a standing wave is similarly formed here, but the direction of the electric field is opposite to that of the previous standing wave and cancels out. Therefore, when the barriers are arranged at ½ of the guide wavelength, electromagnetic waves having the guide wavelength cannot exist in the region sandwiched between the conductors above and below. That is, a band gap is formed.

  In Example 2, in the package having the same periodic structure as in Example 1, when the value of D3 was changed, it was examined in which range the value of D5 would form a band gap in the vicinity of 77 GHz.

  First, when only the value of D5 was changed under exactly the same conditions as in Example 1, it was confirmed that a band gap was formed in the vicinity of 77 GHz if the value of D5 was 0.9 mm or less. Moreover, when the value of D3 was 1.0 mm and the value of D5 was changed, it was confirmed that a band gap was formed in the vicinity of 77 GHz when the value of D5 was 1.0 mm or less.

  In the third embodiment, when there are three local ports 100 and three reception ports 101 to 103, an effective structure for increasing isolation between ports is shown. Since there are a plurality of ports, in the periodic structure as in the first embodiment, the plate is not orthogonal to the line connecting certain ports. Therefore, as shown in FIG. 6, a package having a structure in which a periodic structure composed of two plates is perpendicular to each other in the arrangement direction and the plate and the plate cross in a T shape. In FIG. 6, as in FIG. 1, a perspective view is shown so that the structure inside the package can be seen. Note that the chip 105 mounted on the substrate 110 is a dummy. On the substrate 110, a line 106 connecting the chip 105 and the local port 100, a line 107 connecting the chip 105 and the reception port 101, a line 108 connecting the chip 105 and the local port 102, and a line connecting the chip 105 and the local port 103. 109 is formed. The numerical values of D1 to D5 are all the same as in the first embodiment.

  FIG. 7 shows, as equipotential lines, electric field distribution in a plane parallel to the substrate 110 connecting the front end surfaces of the plate when an electromagnetic wave of 76.5 GHz is input from the local port 100. FIG. The electric field distribution on the end face of the plate when an electromagnetic wave of 76.5 GHz is input is shown as an equipotential line. As shown in FIG. 7, it can be seen that the input from the local port 100 is orthogonal to the plate having the periodic structure, so that the propagation of electromagnetic waves can be effectively suppressed. On the other hand, as shown in FIG. 8, the input from the reception port 102 is orthogonal to the plate having the periodic structure and is parallel to the plate arranged from the local port 100, but between the substrate 110 and the substrate 110. There is a gap in the wall and it is not a complete wall. For this reason, it can be seen that the signal from the reception port 102 is not effectively suppressed, and a standing wave is formed everywhere. However, the electric field is not strong on the chip 105 and the lines 106, 107, and 109 that require isolation. In other words, in the structure of Example 3, the electromagnetic wave filtering function due to the periodic structure is weak, and the formation of standing waves cannot be suppressed. However, there are areas that do not want to be affected by electromagnetic waves, such as on the line or on the chip. It can be adjusted so that it does not become a portion with a strong electric field. In this way, in the third embodiment, the isolation between the ports is increased.

  FIG. 9 is a graph in which the isolation between the local port 100 and the reception port 101 is measured. When the lid is not provided, when the lid without the periodic structure is used, when the periodic lid 1 (the lid having the structure of the first embodiment) is used, and when the periodic lid 2 (the lid having the structure of the third embodiment) is used, Isolation was measured. The frequency to be suppressed is around 77 GHz. As a result, as shown in FIG. 9, when the lid without the periodic structure is used, the deterioration is about 15 dB compared to the case without the lid. On the other hand, when the periodic cover 2 is used, it is about 20 dB better than when the periodic cover 2 is not used.

  FIG. 10 is a graph in which the isolation between the reception port 101 and the reception port 102 is measured. Isolation was measured for the following three cases: when the lid was not used, when the lid without the periodic structure was used, and when the cycle lid 2 was used. Similarly, the frequency to be suppressed is around 77 GHz. When the lid without the periodic structure is used, the deterioration is about 10 dB compared to the case without the lid. On the other hand, when the periodic lid 2 is used, it is about 8 dB better than when the lid is not used.

  As described above, by using the structure of Example 3, the isolation between the ports could be improved.

  The semiconductor package of the present invention is advantageous in that resonance within the package and deterioration of isolation between ports can be prevented, and miniaturization and cost reduction are possible.

1 is a perspective view of a semiconductor package of Example 1. FIG. 2 is a cross-sectional view of the semiconductor package of Example 1. FIG. The electric field distribution map in a semiconductor package. The electric field distribution map in a semiconductor package. An explanatory view of band gap formation. FIG. 10 is a perspective view of a semiconductor package of Example 3. FIG. 6 is an electric field distribution diagram when input from the local port 100. The electric field distribution diagram in the case of inputting from the reception port 102. FIG. 6 is a measurement diagram of isolation between the local port 100 and the reception port 101. FIG. 6 is a measurement diagram of isolation between the reception port 101 and the reception port 102;

10, 110: Substrate 11: Cover 12: Input port 13: Output port 14a-14f: Board 16, 105: Chip 17, 18, 106-109: Line 100: Local port 101-103: Reception port

Claims (4)

In a rectangular parallelepiped semiconductor package comprising a substrate on which a millimeter wave semiconductor device is installed and a conductive lid that covers and seals the substrate,
A first port provided oppositely in the first axial direction to input or output electromagnetic waves; and a second port;
A third port provided oppositely in a second axis direction orthogonal to the first axis, for inputting or outputting electromagnetic waves, and a fourth port;
An upper surface on the inner side of the lid in the first region that bisects the semiconductor package is erected toward the substrate side, and inputs and outputs to the first port and the second port, and the inside of the semiconductor package A first periodic structure composed of a plurality of conductive plates that are perpendicular to the one axis that is the traveling direction of the propagating electromagnetic wave and that are periodically arranged along the first axis ;
An upper surface on the inner side of the lid in a second region different from the first region that bisects the semiconductor package is erected toward the substrate side, and inputs and outputs to the third port and the fourth port. A second periodic structure comprising a plurality of conductive plates that are perpendicular to the second axis, which is the traveling direction of electromagnetic waves propagating in the semiconductor package, and are periodically arranged along the second axis When
Have
The first periodic structure and the second periodic structure are arranged in a T shape, with the arrangement directions of the plates of the respective periodic structures being orthogonal to each other,
The interval between the plates is 1/2 × 0.8 to 1/2 × 1.2 of the guide wavelength of the electromagnetic wave propagating,
The height of the plate is 1/4 × 0.8 to 1/4 × 1.2 of the in-tube wavelength of the electromagnetic wave ,
The semiconductor package is characterized in that a distance between the plate and the substrate is 1.0 mm or less . The semiconductor package according to claim 1, wherein the lid and the plate are formed by pressing a metal plate. The lid and the plate are integrally molded by resin molding,
The semiconductor package according to claim 1, wherein metal plating is applied to surfaces of the lid and the plate. The semiconductor package according to claim 1, wherein the lid and the plate are integrally formed by aluminum die casting.