JP2000223610A - Circuit board for millimeter wave semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the resonance frequency generated within space to the frequency free of influence on a used frequency band, by forming a plurality of potential ranges earth in circular form, by the via holes consisting of the conductive material for connecting the potential pattern at a millimeter wave element mounting face with the earth potential pattern on the rear. SOLUTION: Circuit patterns 7a (pattern for input and output) and 7b (pattern for earth potential) for mounting a millimeter wave semiconductor element are made at one side of a circuit board. The diameter of a via hole 9 is 100 μm, and the pitch is 400-500 μm, and it is connected to the earth potential pattern on the rear of the circuit board. The dimension of a via hole row A1 is 0.91 mm, and the dimension of a via hole row A2 is 0.69 mm, and the dimension of a via hole row B is 2.2 mm, and a potential region 10 is divided into four places of in rectangular rings by via hole rows 9. Then, a millimeter wave semiconductor element consisting of GaAs of 2 mm×3 mm where a metallic bump electrode consisting of gold is bonded by thermocompression onto the bonding pad at the circuit formation face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board for a millimeter-wave band semiconductor, which is a dielectric circuit board on which a millimeter-wave band semiconductor element is mounted by a flip chip bonding method.

[0002]

2. Description of the Related Art In recent years, large-capacity, high-speed wireless communication in the millimeter wave band of 30 to 300 GHz has been attracting attention as the speed of information processing apparatuses has been improved and the resolution of image processing apparatuses has been increased.
In order to configure such a millimeter wave band wireless device, a high performance millimeter wave band semiconductor device is indispensable. A millimeter wave band semiconductor device is obtained by mounting a millimeter wave band semiconductor element on a dielectric circuit board on which a circuit pattern is formed.

However, when a millimeter-wave band semiconductor element is electrically connected to a dielectric circuit board by a wire bonding method widely used in the manufacture of semiconductor devices,
There is a problem that the signal is greatly attenuated due to the influence of the inductance of the metal wire connecting the signal terminal and the circuit board, and desired characteristics cannot be obtained. Therefore, a flip-chip bonding method having a small inductance at a connection portion is used as a mounting method of a millimeter-wave band semiconductor device.

A mounting structure of a conventional millimeter-wave band semiconductor device using a flip chip bonding method will be described with reference to FIGS. FIG. 6 is a schematic diagram of a circuit pattern formed on one surface of a dielectric circuit board for mounting a millimeter-wave band semiconductor element by a flip chip bonding method. FIG. 7 is a circuit diagram of the circuit pattern of FIG. It is a schematic diagram of the AA 'section of a dielectric circuit board when a wave band semiconductor element is mounted.

[0005] Millimeter-wave band semiconductor device 1 made of a material such as GaAs (1 in FIG. 6 shows the outer shape of the millimeter-wave semiconductor device).
Has a circuit of a millimeter-wave band device formed on a circuit forming surface 2 by a wafer process technology, further provided with a bonding pad 3 as a signal input / output terminal, and a gold plating on the surface thereof for the purpose of reducing connection resistance. And the like, and on the bonding pad, a metal bump electrode 4 made of gold or the like (4 in FIG. 6 shows the external shape of the metal bump electrode in the plane direction).
Are formed.

On the other hand, a circuit pattern 7 made of a conductive material is formed on a millimeter-wave semiconductor element mounting surface 6 of a circuit board 5 made of a dielectric material such as a ceramic. Gold plating is applied. The circuit pattern is roughly divided into a signal input / output pattern 7a and a ground potential pattern 7b. A ground potential pattern 8 is formed on the back surface of the millimeter-wave semiconductor element mounting surface 6 of the circuit board 5. Surface ground potential pattern 7b
And the ground potential pattern 8 on the back surface are connected by via holes 9 filled with a conductive material such as tungsten paste. The via hole 9 is disposed on the outer peripheral portion of the ground potential circuit pattern 7b, and forms a potential region 10 which is annularly grounded on the outer peripheral portion of the millimeter wave band semiconductor element 1.

A circuit forming surface 2 of the millimeter-wave band semiconductor device 1;
The metal projecting electrode 4 is thermocompression-bonded so that the circuit pattern 7 of the dielectric circuit
Bonded to the surface.

Thereafter, in order to protect the external environment, the millimeter-wave band semiconductor element 1 is hermetically sealed (not shown), and if necessary, an antenna for receiving a millimeter-wave charged wave is attached (not shown). ), A millimeter-wave band semiconductor device is obtained.

[0009]

However, when the millimeter-wave band semiconductor element 1 is mounted on the dielectric circuit board 5 having the conventional structure by the flip-chip bonding method, the semiconductor element 1 is arranged on the outer peripheral portion of the ground potential circuit pattern 7b. In addition, a via region 9 connected to the ground potential pattern 8 on the back surface forms an annularly grounded potential region 10 on the outer peripheral portion of the millimeter wave band semiconductor device 1.

As a result, when the effective wavelength of the millimeter wave band electromagnetic wave radiated from the circuit forming surface 2 of the millimeter wave band semiconductor device 1 is shorter than the annularly grounded potential region 10, if the effective frequency band or the circuit pattern 7 Depending on the design value, resonance may occur at a frequency lower than the operating frequency band within the annularly grounded potential region 10, which may adversely affect the characteristics of the millimeter-wave band semiconductor device 1.

[0011]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems, and the invention according to claim 1 is a dielectric circuit board on which a millimeter-wave band semiconductor device is mounted. Then, a plurality of annularly grounded potential regions are formed by via holes made of a conductive material that connect at least the ground potential pattern on the surface on which the millimeter-wave band semiconductor element is mounted and the ground potential pattern on the back surface of the surface. A circuit board for a millimeter-wave band semiconductor, characterized in that:

According to a second aspect of the present invention, in the millimeter wave band semiconductor circuit board according to the first aspect, the annularly grounded potential region has a substantially rectangular shape, and the length of the short side of the rectangle Is set to 以下 or less of the effective wavelength.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram of an example of a millimeter-wave band semiconductor circuit board of the present invention in which a potential region in which a dielectric portion is grounded in a rectangular ring by a via hole is divided into 60-GHz bands. It is the schematic which shows the surface circuit pattern of a board | substrate. FIG. 8 is a schematic diagram of a surface circuit pattern of a conventional millimeter-wave band semiconductor circuit board in which there is no division of a potential region in which a dielectric portion is grounded in a rectangular ring shape by a via hole.

The dielectric circuit board used this time is made of, for example, alumina ceramic, 150 μm in thickness, and has a relative dielectric constant of about 8.9. When this substrate material is used at a frequency of, for example, 60 GHz, the effective wavelength is about 2 mm.

A circuit pattern 7a, 7b for mounting a millimeter wave band semiconductor element is formed on one surface of the circuit board shown in FIG. 7 described in the prior art. Circuit pattern 7
a is a pattern for millimeter wave band signal input / output, and the circuit pattern 7b is a pattern for ground potential. The diameter of the via hole 9 is 100 μm, and the pitch of the via hole is 400 to 4
The via hole is filled with a tungsten paste, and is connected to a ground potential pattern (not shown) on the back surface of the circuit board.

In the schematic diagram of the conventional millimeter wave band semiconductor element mounting circuit pattern shown in FIG. 8, the dimension of the via hole row A is 3.2 mm and the dimension of the via hole row B is 2.2 mm. A ground potential region 10 is formed in a rectangular ring shape at three places, and its size is 3.2 mm.
× 2.2 mm.

On the other hand, in the schematic diagram of the circuit board for a millimeter wave band semiconductor device of the present invention shown in FIG. 1, the dimension of the via hole row A1 is 0.91 mm, and the dimension of the via hole row A2 is 0.69 m.
m, the dimension of the via hole row B is 2.2 mm, and the potential region 1 is grounded into four rectangular rings by the via holes 9.
0 are formed separately, and their dimensions are 0.91 mm x
2.2 mm (2 places), 0.69 mm x 2.2 mm (2
Places).

6 and 7, a metal bump electrode 4 made of gold is formed on the bonding pad 3 on the circuit forming surface 2 in the same manner as that shown in FIGS.
The input / output characteristics of a sample manufactured by thermocompression bonding of a millimeter-wave band semiconductor device 1 made of GaAs of 3 mm by flip chip bonding were measured.

As a result, in the conventional circuit board for millimeter wave band semiconductor shown in FIG. 8, characteristic deterioration due to resonance was confirmed at about 55 GHz, and it was difficult to use in the 60 GHz band. On the other hand, in the millimeter-wave band semiconductor circuit board of the present invention shown in FIG. 1, the same resonance occurs at 63 GHz.
It was confirmed that use in the 0 GHz band was sufficiently possible.

Not only from the above results, but also from a series of other studies in the present invention, the frequency of occurrence of the resonance is
It has been found to occur in a potential region 10 grounded in a rectangular ring formed by the via hole 9. Furthermore, of the geometrical dimensions of the potential region 10 grounded in a rectangular ring, the short side is divided into a plurality of parts so that the dimension of the short side is equal to or less than half the effective wavelength. It has become clear that the occurrence of resonance can be avoided.

The shape and division method of the potential region 10 grounded in the form of a rectangular ring are not limited to those shown in FIG.

FIG. 2 shows a circuit pattern of another millimeter-wave band semiconductor element mounting portion having a rectangular annular ground potential divided into three parts.
FIG. 3 shows a circuit pattern of another millimeter-wave band semiconductor element mounting portion having a rectangular annular ground potential divided into two parts, and FIG. 4 shows a circuit pattern of another millimeter wave band semiconductor element mounting part having a rectangular annular ground potential divided into nine parts. FIG. 5 shows a circuit pattern of another millimeter-wave band semiconductor element mounting portion having a rectangular annular ground potential and a part of the ground potential pattern divided into two circuit patterns.

The same effect can be obtained even in a structure in which one end of the via hole is grounded and the other end is open as shown in the pattern division part of FIG.

It should be noted that the present invention is characterized in that a plurality of rectangular ring-shaped ground potential areas are provided, that is, the conventional rectangular ring-shaped ground potential area is divided, and the other parts are the same as the conventional one. The description is omitted here.

[0026]

According to the first or second aspect of the present invention,
Within the space of the annularly grounded potential region formed by a via hole made of a conductive material that connects at least the ground potential pattern on the surface on which the millimeter-wave band semiconductor element is mounted and the ground potential pattern on the back surface of the surface. Since the frequency of the generated resonance can be increased to a frequency range that does not affect the operating frequency band, a millimeter-wave band semiconductor device that does not deteriorate the characteristics of the mounted millimeter-wave band semiconductor element can be configured.

[Brief description of the drawings]

FIG. 1 is a circuit pattern of a millimeter wave band semiconductor element mounting portion of a circuit board for a millimeter wave band semiconductor according to the present invention.

FIG. 2 is a circuit pattern of a millimeter wave band semiconductor element mounting portion of another millimeter wave band semiconductor circuit board of the present invention.

FIG. 3 is a circuit pattern of a millimeter wave band semiconductor element mounting portion of another circuit board for a millimeter wave band semiconductor according to the present invention.

FIG. 4 is a circuit pattern of a millimeter wave band semiconductor element mounting portion of another millimeter wave band semiconductor circuit board of the present invention.

FIG. 5 is a circuit pattern of a millimeter wave band semiconductor element mounting portion of another millimeter wave band semiconductor circuit board of the present invention.

FIG. 6 is a schematic diagram of a circuit pattern for mounting a millimeter-wave band semiconductor device by a flip chip bonding method.

7 is a schematic view of a cross section taken along the line AA ′ of the dielectric circuit board when a millimeter-wave band semiconductor element is mounted on the circuit pattern of FIG. 6;

FIG. 8 is a circuit pattern of a millimeter wave band semiconductor element mounting portion of a conventional circuit board for a millimeter wave band semiconductor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Millimeter wave band semiconductor element 2 Millimeter wave band circuit formation surface 3 Bonding pad 4 Metal bump electrode 5 Dielectric circuit board 6 Millimeter wave band semiconductor element mounting surface 7 Circuit pattern 7a Signal input / output pattern 7b Ground potential pattern (millimeter wave band 8 Ground potential pattern (opposite side of millimeter wave band semiconductor device mounting surface) 9 Via hole 10 Potential region grounded in a rectangular ring

Claims (2)

[Claims] 1. A dielectric circuit board on which a millimeter-wave band semiconductor device is mounted, wherein at least a ground potential pattern on a surface on which the millimeter wave band semiconductor device is mounted and a ground potential pattern on a back surface of the surface are provided. A circuit board for a millimeter-wave band semiconductor, wherein a plurality of potential regions grounded annularly are formed by via holes made of a conductive material to be connected. 2. The circuit board for a millimeter-wave band semiconductor according to claim 1, wherein the annularly grounded potential region has a substantially rectangular shape, and a length of a short side of the rectangle is を of an effective wavelength. A circuit board for a millimeter-wave band semiconductor, characterized in that: