JP4363717B2 - High frequency semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-frequency semiconductor device used for communication equipment or sensors using microwaves or millimeter waves.
[0002]
[Prior art]
Conventionally, an electronic component such as a high-frequency semiconductor circuit that operates in a microwave or millimeter-wave band has a circuit mounted inside a housing of a high-frequency package having a housing made of a dielectric such as metal or ceramic, and is physically or electrically From the viewpoint of proper protection, the housing opening is sealed with a metal lid by brazing or the like, so that it is configured as a practical high-frequency semiconductor device.
[0003]
As a form of such a high-frequency semiconductor device, for example, as shown in an exploded perspective view in FIG. 5, a high-frequency semiconductor element inside the high-frequency package 1 having a metal housing 1 is grounded, for example, on the lower surface. The conductor is accommodated by joining the semiconductor circuit board 2 having the wiring portion on the upper surface with solder or the like, and the input / output terminals and bias terminals of the semiconductor circuit composed of the line conductor 3 and the input / output terminals 4 of the high-frequency package are made of gold. A structure is generally used in which a metal lid 6 made of iron-nickel-cobalt alloy or the like is connected by a wire 5 or the like and sealed by brazing the opening of the housing 1.
[0004]
[Problems to be solved by the invention]
However, in the high-frequency semiconductor device as described above, as a state after sealing, the distance between the line conductor 3 and the metal lid 6 in the wiring portion on the upper surface of the semiconductor circuit is about the height of the wall of the housing 1. However, since the wall of the housing 1 is normally designed as low as possible to suppress unnecessary resonance in the internal space of the housing 1, the distance between the line conductor 3 and the metal lid 6 as the upper ground conductor is small. Since they are close to each other, the impedance of the line conductor 3 is different between the state in which the upper space is open and the state after sealing, and a desired high-frequency characteristic cannot be obtained. there were.
[0005]
The present invention has been made in view of the above problems in the prior art, and its object is to improve the impedance characteristics of the line conductor of the high-frequency semiconductor element in the sealed state so that the sealed state and the upper space are opened. It is an object of the present invention to provide a high-frequency semiconductor device that can reduce the difference in high-frequency characteristics from the above state.
[0006]
[Means for Solving the Problems]
A high-frequency semiconductor device according to the present invention includes a substrate having a high-frequency semiconductor element mounting portion on an upper surface, a high-frequency semiconductor element having a line conductor mounted on the mounting portion, and surrounding the mounting portion on the substrate. A frame body joined in this manner, a high-frequency input / output unit provided through the frame body, and a lid body joined to the upper surface of the frame body. An upper surface ground conductor is formed on the upper surface of the plate, and a lower surface ground conductor is formed on the lower surface except for the portion facing the line conductor of the high-frequency semiconductor element, and the upper surface ground conductor and the lower surface ground conductor are electrically connected inside. The through conductor to be disposed is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
According to the high-frequency semiconductor device of the present invention, a substrate having a mounting portion for mounting a high-frequency semiconductor element on the upper surface, a frame body joined on the substrate so as to surround the mounting portion, and the frame body penetrating therethrough A high-frequency semiconductor device comprising: a high-frequency input / output unit provided; and a lid bonded to the upper surface of the frame for sealing the casing made of the substrate and the frame. The lower surface ground conductor is formed in a range excluding the upper surface where the ground conductor is formed on the entire surface and the portion facing the line conductor of the high-frequency semiconductor element, and the ground conductor is also formed in the upper and lower surfaces of the interior. By using a dielectric plate provided with through conductors such as via conductors, the increase in volume inside the housing is suppressed from the line conductor of the high-frequency semiconductor element to the ground conductor (here, Top ground conductor It is possible to take a distance of greater. Therefore, in order to suppress unnecessary resonance in the internal space of the housing, the housing wall is usually designed as low as possible, and in the conventional high-frequency semiconductor device, a metal lid that is a line conductor and an upper ground conductor in a state after sealing Compared with the case where the impedance of the line conductor of the high-frequency semiconductor element is different between the state in which the upper space is open and the state after sealing, the line in the sealed state High frequency characteristics can be improved by suppressing fluctuations in the impedance of the conductor. As a result, since the difference in characteristics between the sealed state and the state in which the upper space is opened can be reduced, the high-frequency semiconductor device can guarantee the characteristics of the high-frequency semiconductor element alone even after sealing.
[0008]
Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following examples, It does not interfere at all in the range which does not deviate from the main point of this invention.
[0009]
FIG. 1 is an exploded perspective view showing a part of an embodiment of a high-frequency semiconductor device according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA ′ in FIG.
[0010]
In these figures, 11 is a substrate made of metal, 11a is a mounting portion of the high-frequency semiconductor element 13 provided on the upper surface of the substrate 11, and 12 is made of metal joined on the substrate 11 so as to surround the mounting portion 11a. A frame body, and the substrate 11 and the frame body 12 constitute a housing made of metal. Reference numeral 13 denotes a high-frequency semiconductor element having a line conductor 14, in which a ground conductor (not shown) is formed on the lower surface of the semiconductor circuit board 13 a and the line conductor 14 is formed on the upper surface.
[0011]
Reference numeral 15 denotes a high-frequency input / output unit which is fitted into a notch 12a formed on the side wall of the frame body 12 and penetrates the frame body 12. For example, the dielectric substrate 16 is formed on the top surface of the dielectric substrate 16. The line conductor 17 and the dielectric substrate 16 are composed of a dielectric wall member 18 that is joined to the upper surface of the dielectric substrate 16 with a part of the line conductor 17 interposed therebetween. The line conductor 17 of the high-frequency input / output unit 15 and the line conductor 14 of the high-frequency semiconductor element 13 are electrically connected via a bonding wire 19 such as a gold wire.
[0012]
Reference numeral 20 denotes a lid joined to the upper surface of the frame 12, and the high-frequency semiconductor element 13 is mounted on the mounting portion 11 a on the substrate 11 and is hermetically sealed inside the container composed of the substrate 11, the frame 12, and the lid 20. The high-frequency semiconductor device is configured by being housed in the housing.
[0013]
In the lid 20, 21 is a dielectric plate serving as a base material of the lid 20, 22 is an upper surface ground conductor formed on the upper surface of the dielectric plate 21 so as to cover almost the entire surface, and 23 is a lower surface of the dielectric plate 21. The lower surface ground conductor formed in The lower surface ground conductor 23 is formed except for a portion 24 facing the line conductor 14 of the high frequency semiconductor element 13. Reference numeral 25 denotes a through conductor, such as a via conductor, which is formed through the dielectric plate 21 so as to penetrate the upper surface ground conductor 22 and the lower surface ground conductor 23. A plurality of the through conductors 25 are usually provided in order to bring the upper surface ground conductor 22 and the lower surface ground conductor 23 into a good ground state in terms of high frequency, and the lower surface ground conductor 18 is disposed on the lower surface of the dielectric plate 21. When formed and divided except for the portion 24 facing the 13 line conductors 14, each lower surface ground conductor 23 is disposed so as to be electrically connected to the upper surface ground conductor 22.
[0014]
According to such a high frequency semiconductor device of the present invention, the lower surface ground conductor 23 is in a range excluding the vicinity of the portion 24 that is immediately above the line conductor 14 of the high frequency semiconductor element 13 facing the lower surface of the lid 20. Therefore, as the ground conductor disposed on the upper portion of the line conductor 14 by the lid body 20, the upper portion of the line conductor 14 in the upper surface ground conductor 22 formed on the upper surface of the lid body 20 is the line conductor. It will play its role in opposition to 14. At this time, since the electrical distance between the line conductor 14 and the upper surface ground conductor 22 passes through the dielectric plate 21 which is the base material of the lid 20 in the middle of the path, the metal lid as in the conventional case. The electrical distance between the line conductor 14 and its ground conductor (upper surface ground conductor 22) is greater when the height of the same housing wall (frame body 12) is higher than when sealed with a body. Is equivalent to As a result, the electromagnetic field condition for the high-frequency signal of the high-frequency semiconductor element 13 can be brought close to the state in which the upper portion of the line conductor 14 is open. The transmission characteristics of the line conductor 14 in the semiconductor element 13 can also be close to the characteristics evaluated with the upper portion of the line conductor 14 open before mounting.
[0015]
In addition, the electrical distance to the upper ground conductor with respect to the line conductor 14 can be increased by the unnecessary resonance inside the casing formed of the substrate 11 and the frame 12, or the line of the high-frequency semiconductor element 13 mounted inside the casing. In the present invention, the lower surface ground conductor 23 is formed in the vicinity of the upper portion of the line conductor 14 on the lower surface of the lid 20 (the portion 24), and the surface wave is easily generated in the conductor 14. Since the lower surface ground conductor 23 is structured to be electrically connected to the upper surface ground conductor 22 by the through conductor 25 penetrating the lid body 20, the lower surface ground conductor 23 shields most of the housing opening and 24, the electrical distance between the upper surface ground conductor 22 and the line conductor 14 can be secured, so that the increase in the volume of the free space inside the housing composed of the substrate 11 and the frame body 12 is suppressed. While line conductor 14 and upper ground The electrical distance required for grounding with the conductor 22 can be secured.
[0016]
The substrate 11 and the frame 12 in the high-frequency semiconductor device of the present invention are preferably made of metal, and a metal material such as an iron-nickel-cobalt alloy is used as the material. Instead of those made of these metals, a material obtained by depositing a conductor coating such as a metallized metal layer on the surface of the base material of the dielectric material may be used.
[0017]
The high-frequency semiconductor element 13 has various wiring portions in addition to the one in which the line conductor 14 is formed on the upper surface of the semiconductor circuit board 13a as described above as long as it has the line conductor 14 on the upper surface. Can be used.
[0018]
Examples of the material of the dielectric plate 21 serving as a base material of the lid 20 include ceramic materials such as alumina ceramics and mullite ceramics, inorganic dielectric materials such as glass ceramics, PTFE (polytetrafluoroethylene), glass epoxy, An organic resin dielectric material such as polyimide is used.
[0019]
The thickness of the dielectric plate 21 may be appropriately set according to the required characteristics based on the frequency of the used high-frequency signal transmitted by the line conductor 14 and the relative dielectric constant of the dielectric material of the dielectric plate 21.
[0020]
The upper surface grounding conductor 22 and the lower surface grounding conductor 23 formed on the lid 20 are made of thick film printing using a metal material for a high-frequency line conductor, such as Cu, MoMn + Ni + Au.W + Ni + Au.Cr + Cu.Cr + Cu + Ni + Au.Ta2N + NiCr + Au.Ti + Pd + Au.NiCr + Pd + Au, etc. It is formed by a method, a metallizing method, various thin film forming methods, a plating method or the like. Moreover, what was formed by joining electroconductive members, such as metal foil, through a metallized metal layer etc. may be used. The thickness of the upper surface ground conductor 22 and the lower surface ground conductor 23 may be set to an appropriate thickness as a high frequency ground conductor, for example, about 5 μm for a thin film and about 20 μm for a thick film.
[0021]
Further, the through conductor 25 disposed inside the dielectric plate 21 and conducting the upper surface ground conductor 22 and the lower surface ground conductor 23 forms a via conductor, a through-hole conductor or the like, or embeds a rod-shaped metal member or the like. For example, a necessary number may be formed at necessary portions so that a desired grounding state can be obtained in terms of high frequency. For example, regarding the material of the through conductor 25, various conductive materials can be used as long as they can be formed by a process applicable to the dielectric plate 21 of the base material of the lid 20. The cross-sectional shape of the through conductor 25 can be various shapes such as a circle and a rectangle, and the size of the through conductor 25 is also particularly limited as long as it can satisfy the condition of the interval between the through conductors 25 is not. In addition, it is desirable that the interval between the through conductors 25 be about a quarter wavelength or less in the used frequency band because a good grounding state can be obtained. Furthermore, it is better to increase the number of through conductors 25 as much as possible within a possible range.
[0022]
【Example】
Next, specific examples of the high-frequency semiconductor device of the present invention will be described.
[0023]
First, using a substrate and frame made of an iron-nickel-cobalt alloy, a metal housing having a length of 3.0 mm × 2.2 mm × 0.45 mm and a thickness of 0.5 mm was prepared. The length x width x length x width x thickness 2.0 mm x 1.2 mm x 0.2 mm alumina ceramics (relative permittivity 9.6) on the top surface of the substrate inside the housing as a high-frequency semiconductor element A microstrip line substrate for characteristic comparison evaluation formed by forming a microstrip line conductor having a thickness of 2.0 mm × 0.22 mm × 5 μm was mounted and mounted by soldering. Next, on the upper surface of the opening of the frame body, the longitudinal center of the entire upper surface and the lower surface of the dielectric plate made of alumina ceramics (relative permittivity 8.8) of length x width x thickness 4.0 mm x 2.2 mm x 0.2 mm An upper surface ground conductor and a lower surface ground conductor are formed by depositing a Ni + Au plating layer having a thickness of 2 to 6 μm on a tungsten metallized layer having a thickness of about 10 μm, respectively, in a region excluding a region having a width of 0.4 mm centering on the line. In addition, a via conductor having a diameter of 100 μm, which is made of tungsten, which passes through the dielectric plate and makes the upper surface ground conductor and the lower surface ground conductor conductive, has an interval between the centers of 400 μm and is 50 μm from the end of the lower surface ground conductor 23. The lid having a structure formed so as to be aligned at the position was joined with AgCu solder to produce the high-frequency semiconductor device A of the present invention.
[0024]
Further, as a comparative example, the same metal casing as described above and a microstrip line substrate for characteristic comparison evaluation as a high-frequency semiconductor element are used, and length × width × thickness is formed on the upper surface of the frame opening of the casing. A metal lid made of an iron-nickel-cobalt alloy of 4.0 mm × 2.2 mm × 0.2 mm was joined in the same manner to produce a conventional high-frequency semiconductor device B. Furthermore, using the same metal casing as described above and a microstrip line substrate for characteristic comparison evaluation as a high-frequency semiconductor element, a high frequency in which the upper surface of the frame opening of the casing is opened without bonding the lid A semiconductor device C was produced.
[0025]
Then, for these high-frequency semiconductor devices A, B, and C, the transmission characteristics of the microstrip line of the microstrip line substrate for characteristic comparison evaluation mounted inside the metal casing are evaluated by network analyzer measurement, and the microstrip line Impedance and propagation constant were determined. These results are shown in FIG. 3 and FIG.
[0026]
FIG. 3 is a diagram showing the characteristics of the characteristic impedance Z ₀ with respect to the frequency of the microstrip line in the metal housing in each of the high-frequency semiconductor devices A to C. The horizontal axis represents the frequency (unit: GHz), and the vertical axis Represents a characteristic impedance Z ₀ value (unit: Ω), and characteristic curves A to C represent frequency characteristics in the high-frequency semiconductor devices A to C, respectively. As can be seen from these, the characteristic impedance in the high-frequency semiconductor device A of the present invention is such that the upper part of the metal casing is joined by a lid, as compared with the characteristic impedance in the high-frequency semiconductor device B employing the conventional sealing structure. The high-frequency semiconductor device C is in an open state and has a value closer to the characteristic impedance, and the high-frequency semiconductor device can guarantee the impedance characteristic of the line conductor closer to the impedance characteristic in the open state even after the lid is joined and sealed. It is a semiconductor device.
[0027]
4 is a diagram showing the characteristics of the propagation constant β with respect to the frequency of the microstrip line inside the metal housing in each of the high-frequency semiconductor devices A to C. The horizontal axis represents the frequency (unit: GHz) and the vertical axis represents the frequency. The axis represents the propagation constant β (unit: rad / m), and the characteristic curves A to C show the frequency characteristics in the high-frequency semiconductor devices A to C, respectively. As can be seen from these, the propagation constant is not different between the high-frequency semiconductor devices A and C. According to the high-frequency semiconductor device A of the present invention, the electrical length of the line conductor of the high-frequency semiconductor element is guaranteed even after the lid is sealed. It has been confirmed that.
[0028]
Based on the above results, the high-frequency semiconductor device of the present invention has a top ground conductor on the top surface of the dielectric plate as a lid and a bottom ground conductor on the bottom surface except for the portion facing the line conductor of the high-frequency semiconductor element. In addition, by sealing the high-frequency semiconductor element using what is provided with a through conductor that connects the upper surface ground conductor and the lower surface ground conductor inside, while suppressing the generation of unnecessary resonance or surface waves, In addition, since the distance to the ground conductor at the top of the line conductor can be increased while suppressing an increase in volume inside the housing, the line conductor in the wiring section on the upper surface of the high-frequency semiconductor element as in the past is used as a state after sealing. The distance from the lid is about the height of the casing wall (frame body) designed to be as low as possible in order to suppress unnecessary resonance in the internal space of the casing, but the line conductor as in the conventional metal lid And top Compared to the case where the impedance of the line conductor differs between the state in which the upper space is opened due to the closeness of the ground conductor and the state after sealing, the line conductor and the upper-surface ground conductor facing it are different. It was possible to increase the electrical distance to improve the impedance characteristic of the line conductor in the sealed state, and it was confirmed that the high-frequency semiconductor device having a good impedance characteristic of the line conductor even after sealing was confirmed.
[0029]
Note that the above are merely examples of the embodiments of the present invention, and the present invention is not limited to these embodiments, and various modifications and improvements may be added without departing from the scope of the present invention. .
[0030]
【The invention's effect】
According to the high frequency semiconductor device of the present invention, the substrate having the mounting portion for the high frequency semiconductor element on the upper surface, the high frequency semiconductor element having the line conductor mounted on the mounting portion, and the mounting portion on the substrate. A frame body joined to surround the frame body, a high-frequency input / output unit provided through the frame body, and a lid body joined to the upper surface of the frame body, The upper surface ground conductor is formed on the upper surface of the dielectric plate, and the lower surface ground conductor is formed on the lower surface except for the portion facing the line conductor of the high-frequency semiconductor element, and the upper surface ground conductor and the lower surface ground conductor are formed inside. Since the through conductor that conducts the current is disposed, as a state after sealing, the distance between the line conductor and the lid in the wiring portion of the high-frequency semiconductor element causes unnecessary resonance in the internal space of the housing. Low as much as possible to suppress The height of the case wall (frame body) to be designed is about the same, but the distance between the line conductor and the upper ground conductor is close as in the case of using a conventional metal lid, and the upper space is reduced. The impedance of the line conductor is no longer different between the open state and the sealed state, and the electrical connection up to the top ground conductor facing the top of the line conductor is suppressed while suppressing the increase in volume inside the housing. Since the distance can be increased, the impedance characteristic of the line conductor of the high-frequency semiconductor element in the sealed state can be improved, and the high-frequency semiconductor device having a good impedance characteristic of the line conductor in the sealed state can be obtained.
[0031]
As described above, according to the present invention, the impedance characteristic of the line conductor of the high-frequency semiconductor element in the sealed state can be improved, and the difference in high-frequency characteristics between the sealed state and the state in which the upper space is opened can be reduced. It was possible to provide a high-frequency semiconductor device that can be used.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a part of an example of an embodiment of a high-frequency semiconductor device according to the present invention.
FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG.
FIG. 3 is a diagram showing characteristics of characteristic impedance Z ₀ with respect to frequency of a microstrip line inside a metal housing in a high-frequency semiconductor device.
FIG. 4 is a diagram showing a characteristic of a propagation constant β with respect to the frequency of a microstrip line inside a metal housing in a high-frequency semiconductor device.
FIG. 5 is an exploded perspective view showing an example of a conventional high-frequency semiconductor device.
[Explanation of symbols]
11 ... Board
11a ・ ・ ・ ・ Mounting part
12 ... Frame
13 ... High frequency semiconductor devices
14 ・ ・ ・ ・ ・ Line conductor
15 ・ ・ ・ ・ ・ High frequency input / output section
20 ... Cover body
21 ... Dielectric plate
22 …… Top grounding conductor
23 ・ ・ ・ ・ ・ Bottom ground conductor
24... Part of the high-frequency semiconductor element 13 facing the line conductor 14
25 ・ ・ ・ ・ ・ Penetration conductor

Claims (3)

A substrate having a mounting portion for mounting a high-frequency semiconductor element having a line conductor on the upper surface;
A frame joined on the substrate so as to surround the mounting portion;
A dielectric plate, an upper surface ground conductor provided on the upper surface of the dielectric plate, a lower surface ground conductor provided on the lower surface of the dielectric plate, an inner surface of the dielectric plate, and the upper surface ground conductor and A lid that is connected to the upper surface of the frame body, and the high-frequency semiconductor element is mounted on the mounting portion. A lid provided only with the dielectric plate and the upper surface ground conductor, directly above the upper line conductor,
A high-frequency package comprising: The high-frequency package according to claim 1, further comprising a high-output input / output unit provided through the frame . The high-frequency package according to claim 1 or 2,
Provided in the mounting portion, a high-frequency semiconductor element having a line conductor on the upper surface,
A high frequency semiconductor device comprising:

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