JPS6214944B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present application relates to a semiconductor device that can efficiently dissipate generated heat.

Conventionally, heat generated in integrated circuit devices in which multiple circuit elements are formed on one semiconductor substrate protects the semiconductor substrate on which the circuit is formed and the circuit elements.
Conducts through insulating materials such as SiO ₂ . Of this, the heat conducted to the insulating material is absorbed by the phosphor glass (PSG) that protects the integrated circuit and the _N2 contained in it.
It is conducted to the package material such as epoxy resin through gas etc. Heat is then dissipated to the outside from this epoxy resin. Furthermore, the heat to the substrate is dissipated to the outside by a metal conductive plate or the like with high thermal conductivity on which the substrate is attached, which also acts as a heat sink.
Si is commonly used as a substrate when forming integrated circuits. This thermal conductivity is approximately 0.84 J/cmsec, and the thermal conductivity of SiO ₂ is approximately 1.9×10 ^-3 J/cmsec,
The thermal conductivity of PSG and epoxy resin is also approximately on the same order as SiO ₂ . Also, the thermal conductivity of _N2 gas is approximately
It is 5.4×10 ^-4 J/cmsec. As you will see
The thermal conductivity of SiO ₂ , PSG, epoxy resin, and N ₂ gas is very low compared to that of Si. For this reason, the metal wiring and the like that constitute the circuit, which have poor heat conduction efficiency, remain at approximately the same temperature as the heat source, and the temperature gradually rises. This may cause deterioration of the element, variation in characteristics, etc.

It is an object of the present application to provide a semiconductor device that can eliminate the above-mentioned drawbacks and efficiently dissipate heat.

Another purpose of the present application is to protect circuit elements.
Almost the entire surface of an insulator such as SiO ₂ is coated with a substance with high thermal conductivity such as a metal, and this material absorbs the heat conducted through the insulator and transfers that heat to the contact area with the substrate. An object of the present invention is to provide a semiconductor device in which heat is efficiently dissipated by conduction to a substrate through the heat exchanger.

The present application will be explained based on the drawings.

FIG. 1 shows a MOS transistor formed on a Si substrate. After forming a field oxide film 2 made of SiO ₂ on a Si substrate 1, a part of this oxide film 2 is removed, and a gate oxide film 3 made of SiO ₂ and a polycrystalline Si layer that will become the gate electrode are deposited on that part. form 4. A portion of this gate oxide film 3 and polycrystalline Si layer 4 is removed, and impurities such as boron are diffused into the substrate 1 from this portion to form a source 5 and a drain 6. Afterwards, the gate electrode is insulated with an insulating film 7 made of SiO ₂ or the like, and then a source electrode 8 and a drain electrode 9 are formed of Al or the like. A plurality of such transistors are formed in an integrated circuit device.

Thereafter, as shown in FIG. 2, an insulating layer 10 made of SiO ₂ is formed over the entire surface.

Next, as shown in Figure 3, the SiO ₂ layer is removed from the part where the circuit element is not formed, and the contact hole 1
Form 1. It is preferable that the area of this contact hole 11 be large. This is because, in order to efficiently conduct the heat conducted to the metal layer formed in a later process to the substrate 1, the larger the contact area between the metal layer and the substrate 1, the better the efficiency of heat conduction. be.

Next, as shown in FIG.
Then, the entire surface of the insulating layer 10 is covered with an Al layer 12. This Al layer 12 does not cover the bonding pad or the scribe area. This is because the bonding pad is connected to the connection lead to the external terminal, and the thinner the scribe portion is, the easier it is to scribe. Furthermore, the thermal conductivity of Al is approximately 2.3 J/cmsec, which is much higher than that of SiO ₂ and the like.

The circuit formed in this way is protected by a protective film such as PSG. Then, the substrate 1 is soldered to a metal conductive plate or the like, and connected to external leads using lead wires. It is then molded with resin such as epoxy. This metal conductive plate is also effective as a heat sink.

By forming an integrated circuit as described above, the heat generated during its operation can be efficiently dissipated to the outside through the substrate and the heat sink.

This will be explained below.

First, a portion of the heat generated by the transistor etc. is directly conducted to the substrate 1. Then, other heat is conducted to the gate electrode protective film 7 and the insulating layer 10, and this heat is further
conducts to the Al layer 12. Most of the heat conducted to the Al layer 12 is conducted to the substrate 1 through the contact portion with the substrate 1. This is the PSG formed on the Al layer 12.
This is because the thermal conductivity of Si is higher than that of the passivation layer and the epoxy resin for the mold on it.

Most of the heat generated in this way is conducted to the substrate 1. Therefore, the generated heat can be efficiently dissipated to the outside through the metal conductive plate, which is also effective as a heat sink to which the substrate 1 is mounted. Thereby, temperature rise can be suppressed, thermal deterioration and characteristic fluctuations of the circuit can be prevented, and reliability of the circuit can be improved.

Furthermore, since the entire surface is coated with Al, it also functions as a shielding material that protects the circuit from external noise.

In addition, Al was used in the example, but this
It goes without saying that other materials with high thermal conductivity may also be used. Further, it is not necessary to bring Al into direct contact with the substrate, and an intermediate layer that can conduct heat well to the substrate may be interposed.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views of a semiconductor device at each step for explaining an embodiment of the present application. 1... Substrate, 10... Passivation layer, 1
1...Contact hole, 12...Al layer.

Claims (1)

[Scope of Claims] 1. A lead frame, a semiconductor substrate placed on the lead frame and having a portion where a circuit element is formed and a portion where no circuit element is formed, an insulating film covering the circuit element. , a thermally conductive layer formed on this insulating film, a protective film formed on this thermally conductive layer, and a portion of the semiconductor substrate and the thermally conductive layer in which the circuit element is not formed to be connected to the insulating film and the thermally conductive layer. A semiconductor device characterized in that the semiconductor device is thermally connected using a material having higher thermal conductivity than the protective film.