JP2001024118A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device with low heat resistance. SOLUTION: A circuit board 11, and a semiconductor chip 12 where, being provided on the circuit board 11, an FET 16 which heats at operation is formed at a part, are provided. Here, a plurality of metal bumps 17a, 17b, and 17c provided on the semiconductor chip 12, as well as a diamond chip 18 provided on the plurality of metal bumps 17a, 17b, and 17c, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor device having improved characteristics of releasing heat generated by active elements formed on a semiconductor chip.

[0002]

2. Description of the Related Art In communication equipment used for microwave communication systems, for example, a GaAs FET chip or a Ga
A semiconductor device constituted by an AsMMIC (microwave monolithic integrated circuit) chip is one of important devices. These semiconductor devices have recently been used in PCS (per
sonal-communication-service
ces) and WLL (wirelwss-local-
loop), and the application field is expanding more and more. For example, mobile phone terminals, etc.
A semiconductor device composed of an sFET chip or a GaAs MMIC chip is incorporated as a power amplification module.

[0003]

By the way, portable telephone terminals are required to be smaller and lighter. For this reason, the required thermal conditions for semiconductor devices used in these devices have become severe. For example, portable telephone terminals are often used under severe thermal conditions. But,
Due to the demand for small size and light weight, FEs that constitute semiconductor devices
When the heat generated by T or the like is released, it is difficult to employ a large cooling structure such as a large envelope or a heat sink.

Therefore, in order to reduce the thermal condition of the semiconductor device, in the case of a GaAs MMIC, a method of dividing an active element portion such as an FET, which is a heat source,
In this case, a method of widening the gate pitch to lower the thermal resistance is adopted.

However, the above-mentioned method causes an increase in the chip size of the semiconductor device, an increase in cost, and a deterioration in characteristics.

An object of the present invention is to solve the above-mentioned disadvantages and to provide a semiconductor device having a low thermal resistance.

[0007]

The present invention comprises a circuit board,
In a semiconductor device comprising: a heating element that generates heat during operation; and a semiconductor chip disposed on the circuit board, a plurality of conductive members provided on the semiconductor chip; And a diamond chip provided on the conductive member.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
An amplifier constituted by an AsMMIC chip will be described as an example with reference to the cross-sectional view of FIG. Reference numeral 11 denotes a circuit board on which a GaAs MMIC chip 12 is fixed by a conductive adhesive. On both sides of the GaAs MMIC chip 12, input / output strip lines 13 and 14 for inputting and outputting signals to and from the GaAs MMIC chip 12 are provided. Note that the input / output port portion of the GaAs MMIC chip 12 and the input / output strip lines 13, 1
4 is connected by a bonding wire 15.

On the GaAs MMIC chip 12, an active element that generates heat in an operating state, for example, an FET 16 is formed. On the GaAs MMIC chip 12, although not shown, other than the FET 16, a circuit pattern forming an impedance conversion circuit, a bonding pad forming an input / output port of a high-frequency signal, and a line supplying DC power are formed. Bonding pads and the like are formed.

Then, conductive members such as metal bumps 17a, 17b, 1
7c is formed at a height of about 20 to 30 μm, and a diamond chip 18 is fixed on the plurality of metal bumps 17a, 17b, 17c.

The diamond tip 18 is, for example, C
A diamond film is formed to a thickness of 50 μm on a silicon substrate by using a VD method or the like, and thereafter, the diamond film is formed only by the diamond film portion obtained by separating the silicon substrate portion, and has a thermal conductivity of 1000 W / m · deg or more. Has become.

The mount of the diamond tip 18 is G
The aAsMMIC chip 12 is mounted on the circuit board 11, and the input / output port portion of the GaAs MMIC chip 12 and the strip lines 13 and 14 are connected by bonding wires 15, and then one surface of the diamond chip 18 is connected. Au / Pt / Ti is metallized in each layer, and the metallized surfaces are metal bumps 17a, 17a.
b, 17c.

In this case, the entire surface of one side of the diamond tip 18 can be metallized. However, if the height of the metal bumps 17a, 17b, 17c is low, the metallized surface may affect the characteristics of the signal transmitted through the GaAs MMIC chip 12. Therefore, when the height of the metal bumps 17a, 17b, and 17c is low, metallization is performed only on portions that are thermocompression-bonded to the metal bumps 17a, 17b, and 17c.

Here, in the semiconductor device having the above-described structure, how the heat generated in the active element portion is dissipated will be described with reference to the schematic structural diagram of FIG. In FIG. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be partially omitted.

For example, when the semiconductor device enters an operation state, the FE formed on the GaAs MMIC chip 12
Heat is generated in the active area such as T16. This heat is transmitted to the circuit board 11 through the heat dissipation path of the GaAs MMIC chip 12, and is radiated from the circuit board 11, as indicated by the solid arrow Y1. At this time, part of the heat generated in the active region such as the FET 16 is dissipated by the metal bumps 17 provided in the vicinity of the active region as indicated by the wavy arrow Y2.
a to the diamond tip 18. The heat transmitted to the diamond tip 18 is the diamond tip 18
Extends in the horizontal direction, and the distance from the active area is
Ga from another metal bump 17b, 17c farther than 7a
It is transmitted to the AsMMIC chip 12. From there, further
The heat is transmitted to the circuit board 11 and is radiated from the circuit board 11.

According to the above-described structure, since the heat dissipation path passing through the diamond tip 18 is provided, the heat emission path increases accordingly, the thermal resistance decreases, and the FET 1
The temperature in the active part, such as 6, drops. Generally, the reliability of a semiconductor device is determined by the active portion at which the temperature is maximized. Therefore, the reliability is improved by lowering the temperature of the active portion. Further, the above-described configuration has a structure in which metal bumps 17a, 17b, and 17c are provided on the GaAs MMIC chip 12, and the diamond chip 18 is disposed thereon. Therefore, it can be easily applied to an existing semiconductor device. Further, since the diamond chip 18 is insulative, the influence on the signal transmitted through the GaAs MMIC chip 12 is small. Further, the change in the spatial impedance is small, and the circuit design becomes easy.

Next, regarding another embodiment of the present invention, G
Figure 3 shows an example of an amplifier composed of an AsMMIC chip.
This will be described with reference to the sectional view of FIG. 3, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be partially omitted.

In this embodiment, a diamond chip 18, which is slightly smaller in size than the GaAs MMIC chip 12, is placed on the GaAs MMIC chip 12 with the insulating adhesive 3.
1 directly mounted.

For mounting the diamond chip 18, for example, the GaAs MMIC chip 12 is mounted on the circuit board 11, and the input / output port portion of the GaAs MMIC chip 12 and the strip lines 13, 14 are connected by the bonding wires 15. Then, the diamond chip 18 coated with the insulating adhesive 31 is
The pressing is performed on the MIC chip 12 by a so-called stamping method.

Also, in order to transfer heat well from the GaAs MMIC chip 12 to the diamond chip 18,
The insulating adhesive 31 has a high thermal conductivity of 3 W / m · deg or more, and has a thickness of 10 μm or less.

Here, in the semiconductor device having the above-described structure, how the heat generated in the active element portion is dissipated will be described with reference to a schematic structural diagram of FIG. 4, parts corresponding to those in FIG. 3 are denoted by the same reference numerals, and redundant description will be partially omitted.

For example, when the semiconductor device enters an operating state, the FE formed on the GaAs MMIC chip 12
Heat is generated in the active area such as T16. This heat is transmitted to the circuit board 11 through the heat dissipation path of the GaAs MMIC chip 12, and is radiated from the circuit board 11, as indicated by the solid arrow Y1. At this time, a part of the heat generated in the active region such as the FET 16 is transmitted to the diamond chip 18 through the thin insulating adhesive 31 as indicated by a wavy arrow Y2. The heat transmitted to the diamond chip 18 spreads in the lateral direction of the diamond chip 18 and is transmitted to the GaAs MMIC chip 12 at a position away from the active area. From there, it is further transmitted to the circuit board 11 and is radiated from the circuit board 11.

Also in the case of the above-described configuration, since the heat dissipation path passing through the diamond tip 18 is provided, the heat emission path increases accordingly, the thermal resistance decreases, and the FET 1
The temperature in the active part, such as 6, drops. Generally, the reliability of a semiconductor device is determined by the active portion at which the temperature is maximized. Therefore, the reliability is improved by lowering the temperature of the active portion. In addition, since the above-described configuration is a configuration in which the diamond chip 18 is bonded on the GaAs MMIC chip 12 with an insulating adhesive, it can be easily applied to an existing semiconductor device. Further, since the diamond chip 18 is insulative, the influence on the signal transmitted through the GaAs MMIC chip 12 can be reduced. Further, since the change in the spatial impedance is small, the circuit design becomes easy.

In each of the above embodiments, a diamond chip composed of only a diamond film is used. However, as a diamond chip, a structure in which a diamond thin film is grown on one surface of a silicon substrate, that is, a so-called diamond-on-silicon chip can be used. In this case, the diamond thin film is disposed such that the side on which the diamond thin film is formed is located on the GaAs MMIC chip side. For example, a portion of the diamond thin film is thermocompression-bonded to a metal bump. Alternatively, a portion of the diamond thin film is bonded onto the GaAs MMIC chip with an insulating adhesive.

In each of the above embodiments, GaAsM
In the description, the heat generated by the MIC chip is radiated. However, the present invention can be applied to other semiconductor chips.

[0026]

According to the present invention, a semiconductor device having low thermal resistance and high reliability can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view for explaining an embodiment of the present invention.

FIG. 2 is a schematic composition diagram for explaining how heat is dissipated in the embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view for explaining another embodiment of the present invention.

FIG. 4 is a schematic composition diagram for explaining how heat is dissipated in another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Circuit board 12 ... GaAs MMIC chip 13, 14 ... Input / output strip line 15 ... Bonding wire 16 ... FET 17a, 17b, 17c ... Metal bump 18 ... Diamond chip

Claims (6)

[Claims] 1. A semiconductor device, comprising: a circuit board; and a heat generating element that generates heat during operation is partially formed, and includes a semiconductor chip disposed on the circuit board. A semiconductor device comprising: a conductive member; and a diamond chip provided on the plurality of conductive members. 2. The semiconductor device according to claim 1, wherein the plurality of conductive members are provided at positions different in distance from the heating element. 3. The semiconductor device according to claim 1, wherein a conductive member is provided near the heating element. 4. The semiconductor device according to claim 1, wherein the plurality of conductive members are formed of metal bumps. 5. A semiconductor device comprising: a circuit board; and a heat generating element that generates heat during operation; and a semiconductor chip disposed on the circuit board, wherein a diamond chip is fixed on the semiconductor chip. A semiconductor device characterized by the above-mentioned. 6. The semiconductor device according to claim 1, wherein the diamond chip is a diamond-on-silicon chip having a diamond thin film grown on one surface of a silicon substrate.