JPH02156555A - Resin sealed semiconductor device - Google Patents

Abstract

PURPOSE:To improve the heat dissipating property of a resin seal semiconductor device by blending, in sealing resin, aluminum powder coated with an aluminum oxide film or an aluminum nitride film, as filling material. CONSTITUTION:In a resin seal semiconductor device 1, a semiconductor element 2 is fixed on a mounting part 3, and connected with leads 4 via bonding wires 5; the whole part is molded with sealing resin 6, thereby protecting the semiconductor element 2 from the ambient air and simplifying the mounting onto a printed board by using the leads 4. In this case, Al powder coated with an aluminum oxide film or aluminum nitride film of 0.5-20.0mum in thickness is blended, as filling material 7, in the sealing resin. Thereby, the thermal conductivity of sealing resin is improved, and excellent heat dissipating property can be obtained.

Description

[Detailed Description of the Invention] [Summary] Regarding the sealing resin used for sealing a resin-sealed semiconductor device, the purpose of improving the heat dissipation property of the sealing resin of the semiconductor device is to incorporate , filled with aluminum powder coated with an aluminum oxide film or an aluminum nitride film with a film thickness of 0.5 to 20.0 μm [Industrial Application Field] This invention relates to a sealing IF resin used for sealing.

2. Description of the Related Art In recent years, there has been remarkable progress in increasing the density and integration of semiconductor devices, mainly integrated circuits (ICs), and the amount of heat generated by semiconductor devices has accordingly increased.

Generally, semiconductor devices are sealed using various methods to protect the elements, but it is important to use materials that are both inexpensive and efficient in heat dissipation. This has become a major issue.

In other words, for microcontrollers, gate arrays, etc. that have high output and large heat dissipation, a heat sink with a thermal conductivity of 400x10 is used.
-'cal/cm-s - So-called ceramic ICs are used, which are sealed with ceramics that have a high value of around 'C.

However, ceramic ICs are generally expensive and have poor mass productivity, so they are often used for limited purposes.

On the other hand, so-called plastic ICs, which are molded and sealed with a sealing synthetic resin suitable for low-pressure molding, are often used because they are easy to mass-produce and are inexpensive.

[Conventional technology]

Various fillers are added to the encapsulating resin used in plastic ICs in order to alleviate the thermal stress caused by the heat generated by the element and to improve the thermal conductivity of the encapsulating resin, which has poor thermal conductivity. It is being said.

Fused silica (Si) is often used as a filler.
oz), but its thermal conductivity is very low compared to ceramic and ivy (15X10-'cal/cm-s
-'C) The heat dissipation of the filler is not satisfactory.

As alternative fillers, crystalline silica powder and alumina (Atzo:+) powder are known.

Crystalline silica has a higher thermal conductivity than fused silica (50X10-'cal/cm + s ・'C), but
This is not a significant improvement, and since the coefficient of linear expansion is large, there is a drawback that the package is likely to crack due to thermal stress.

Alumina powder has a thermal conductivity that is not much different from crystalline silica.
Due to the high content of ionic impurities, the moisture resistance is poor, and the powder itself is hard, causing problems such as abrasion of the molding die.

On the other hand, if we focus on thermal conductivity, for example,
A! metal powder can be a good filler.

However, with unprocessed metal powder, no matter how well it is dispersed in the sealing resin, it is impossible to avoid short circuits between elements, bonding wires, leads, etc. close.

Therefore, a proposal has been made to coat the surface of the metal powder with an insulating resin in advance (Japanese Patent Laid-Open No. 54128276
).

[Problem to be solved by the invention]

As mentioned above, inorganic metal oxides are generally used as fillers added to the sealing resin of plastic ICs, but in order to dissipate the increasingly increasing heat generated by ICs, it is necessary to It would be very convenient if a high metal ↑51 powder could be used.

However, no matter how much metal powder is dispersed in the sealing resin, aggregation of the metal powder and ionization of the metal occur, making it difficult to prevent insulation deterioration and electrical short circuits. there were.

Therefore, it is possible to obtain a semiconductor device molded using a sealing resin kneaded with a filler coated with a thin, uniform film thickness and stable insulating film without impairing the good thermal conductivity of metal. It was requested.

[Means to solve the problem]

The problem mentioned above is that the thickness of the film in the sealing resin is 0.5
This can be achieved by using a resin-sealed semiconductor device in which AN powder coated with an aluminum oxide film or an aluminum nitride film of ~20.0 μm is kneaded as a filler.

[For production]

FIG. 1 is a configuration diagram of an example of a resin-sealed semiconductor device.

In the figure, a resin-sealed semiconductor device 1 includes a semiconductor element 2
is fixed to the mounting part 3 and connected to the leads 4 by bonding wires 5, and the whole is molded with a sealing resin 6 to protect the semiconductor element 2 from the outside air and to prevent printing using the leads 4. This makes it easier to mount it on a board, etc.

In order to dissipate the heat generated from the semiconductor element 2, a filler material 7 is kneaded into the sealing resin 6, which generally has poor thermal conductivity, to improve heat dissipation.

FIG. 2 is a characteristic diagram of a resin-sealed semiconductor device kneaded with the filler of the present invention.

In the figure, the horizontal axis is time, and the vertical axis is the water vapor pressurization test, so-called bias P CT (P
Ressure Cooker Te5t) Indicates the defective rate when the test is conducted.

The sample was made of epoxy sealing resin with an average particle size of 20 μm.
80% by weight of a filler based on AN powder was added and kneaded.

The conditions for the bias PCT test are: temperature 120°C, humidity 1
00% RH 1 pressure 2 atmospheres.

In addition, the evaluation of the sample was conducted as a semiconductor element 2 on a silicon wafer with a pattern width of 3 μm and a pattern gap of 2 μm.
Using a test element wired with an Al2 pattern of 1.5 m, conduction is established between the lead 4 and the lead 4 using a 80-m bonding wire 5. For bias, one of the pair of patterns is grounded, and the other is connected to a 24 V DC voltage. is being applied.

As mentioned above, as the filler 7 for improving the thermal conductivity of the sealing resin 6, metal powder with good thermal conductivity is used.
It is the best filling material.

However, as can be seen from (A) in the same figure, if the Affi powder is used as it is without any treatment, no matter how well it is kneaded into the sealing resin 6, half of it becomes defective in about 24 hours, and the semiconductor It is impossible to avoid insulation deterioration and short circuits between the elements 2, leads 4, bonding wires 5, etc. over a long period of time.

This is A! The surface of the oxide film is covered with an extremely thin oxide film in the atmosphere, but when it is kneaded in the sealing resin as a filler, the oxide film is mechanically destroyed and a tunnel effect occurs. This is because the electrical insulation is insufficient.

On the other hand, by applying oxidation treatment to Al1 powder, 0.5
When the surface is coated with a μm-thick aluminum oxide film, the defect rate is 0 for up to 800 hours, as shown in (b) of the same figure.
%, and even after 2,000 hours, the defective rate is at most 10%.

Furthermore, when the surface is coated with an oxide film of 5 μm, as shown in (c) of the same figure, even after 2,000 hours, the defective rate is 0%, showing very good characteristics.

Even when the surface is coated with an aluminum nitride film, the PCT test results are almost the same as when the surface is coated with an aluminum oxide film, as shown in Figures (D) and (E).

If the particle size of the A f $53 powder of the filler added to the sealing resin is too small, it will be difficult to control the oxidation treatment and nitriding treatment, and if it is too large, the filler will Since the surface area becomes smaller, the effect of imparting thermal conductivity to the sealing resin becomes lower.

FIG. 3 is a diagram showing the relationship between the amount of crosstalk and thermal conductivity of the filling material of the present invention.

In the same figure, it is more effective to have as many stars as possible to mix into the sealing resin, focusing on thermal conductivity.

However, the fluidity of the sealing resin deteriorates, making the commonly performed transfer molding difficult, causing the mold for molding to wear out, or causing the sealing resin itself to function as a binder. There is a limit to this, as it may cause damage to the body.

On the other hand, when the amount of filler kneaded into the sealing resin is reduced, the thermal conductivity decreases rapidly and the effect becomes smaller.

However, there is no particular condition that restricts the lower limit of the amount of crosstalk in the filling material.

FIG. 4 is a diagram showing the relationship between the film thickness and thermal conductivity of the filler of the present invention.

In the figure, when the film is made of aluminum oxide and the thickness of the film is 0.5 μm or less, the thermal conductivity becomes very high, but short circuit failures also increase, making it impractical.

The reason for this is thought to be that the film is mechanically destroyed when the filler is kneaded into the sealing resin, and 0.5 μrn is the lower limit of the film thickness.

On the other hand, when the thickness of the film becomes 20 μm or more, the thermal conductivity decreases drastically and the filler of the present invention becomes ineffective.

In the figure, since the particle size of Affi powder is 100 μrn, when the thickness of the film is 50 μm, the characteristics are close to those of alumina itself.

However, since the particle size of the filler is generally limited to about 100 μm, the effective upper limit for the thickness of the film is 20 μm.

The results described above were exactly the same even when the aluminum oxide film was replaced with an aluminum nitride film.

〔Example〕

FIG. 1 is a configuration diagram of an example of a resin-sealed semiconductor device.

Example: 1 As the filler 7, Aj2 powder having an average particle size of 20 μm was subjected to steam oxidation and coated with an aluminum oxide film having a thickness of 0.5 μm.

For the sealing resin, a mixed resin of epoxy and phenol novolak is used, and 2-undecylimidazole, stearic acid, montana wax, etc. are added, and carbon black is added to bring the filler content to 80% by weight. The mixture was mixed well with a ball mill.

In the DIP type semiconductor device 1 shown in FIG.
The semiconductor element 2 is a test element 2 in which an AI pattern with a pattern width of 3 μm and a pattern gap of 2 μm is wired on a silicon wafer, and both ends of the pattern are connected to leads 4 using bonding wires 5 of AI2. did.

Resin sealing was performed using a molding die, the semiconductor device 1 was formed, and thermal conductivity was measured and reliability was evaluated.

Thermal conductivity was measured by cutting the molded semiconductor device 1 into test pieces, using a heating plate and a spot-type infrared thermometer.

The thermal conductivity of the resin itself without being kneaded with filler is approximately 12.
XIO-'cal/cm + s ・"C, whereas in the example of the sealing resin kneaded with the filler of the present invention, it is 182X10-'cal/cm -s -"
C, and an approximately 15 times higher effect was confirmed.

In addition, in the reliability evaluation, the molding performance as the sealing resin 6 kneaded with the filler of sample 1 was evaluated as the open failure rate through the pattern of the test element 2 and between one dot 4. The open defect rate was 0%.

On the other hand, (b) of FIG. 2 shows the results of a bias PCT test of the semiconductor device 1 molded with the sealing resin 6 kneaded with the filler according to the present invention.

Up to 800 hours, the defective rate was 0%, and even after 2,000 hours, the defective rate was at most 10%.

Example: 2 As the filler 7, the surface of He〇 powder having a particle size of 80 μm was coated with an aluminum oxide film having a thickness of 3.0 μm.

Example: With the same specifications as I, the filler content was blended to be 60% by weight, thoroughly kneaded in a ball mill, a sealing resin was prepared, and a semiconductor device 1 was molded and evaluated.

As a result, the thermal conductivity of the sealing resin mixed with the filler according to the present invention was t54X10-'cal/cm-s
・At °C, the open defect rate was 0%.

Example: 3 As the filler 7, A! with a particle size of 100 μm is used. A film thickness of 15mm is applied to the surface of the powder. A material coated with Oum's aluminum oxide film was used.

Example: With the same specifications as 1, the filler content was mixed to be 70% by weight, thoroughly kneaded in a ball mill, a sealing resin was prepared, and a semiconductor device 1 was molded and evaluated.

As a result, the thermal conductivity of the sealing resin mixed with the filler according to the present invention was 167X10-'cal/cm-s.
℃, the open defect rate was 0%.

Example 4 As the filler 7, Aβ powder having a particle size of 50 μm was heated and nitrided in a nitrogen-containing atmosphere, and the surface was coated with an aluminum nitride film having a film width of 1.0 μm.

Example: With the same specifications as 1, the amount of filler content is Σ(0
They were blended so as to have a weight ratio of 100% and thoroughly kneaded in a ball mill, and a sealing resin was prepared. A semiconductor device 1 was molded and evaluated.

As a result, the thermal conductivity of the sealing resin mixed with the filler according to the present invention was 176X10-'cal/cm-s
・At °C, it was confirmed that the thermal conductivity was approximately 15 times higher than that of the resin itself without the filler.

Furthermore, the open defect rate was 0%.

Comparative Example: 1 Crystalline silica with an average particle size of 80 μm was used as the filler 7, and the mixture was well kneaded in a ball mill with the same specifications as Example 1 so that the filler content was 80%. , a sealing resin was prepared, a semiconductor device 1 was molded, and evaluation was performed.

As a result, the thermal conductivity was 48×10-'cal/cm Hs·'C, which is close to that of crystalline silica alone, but the oven failure rate was a large value of 20%.

In this example, the oxidation treatment on the surface of powder A1 was performed as follows:
Although this was done using water vapor, it can also be done by heating in a gas phase in an oxygen atmosphere or electrochemically in a liquid phase, and modifications such as exposing it to nitrogen plasma are also possible. .

Furthermore, the type and composition of the sealing resin, the blending ratio of the filler, the mixing method, etc. can be modified in various ways depending on the purpose and required performance.

[Effect of the invention] As is clear from the above explanation, according to the present invention, Al
Resin-sealed semiconductor devices are molded by kneading a filler whose powder surface is coated with a film of aluminum oxide or aluminum nitride into a sealing resin. Since it can be made much larger than the thermal conductivity, it greatly contributes to the manufacture of semiconductor devices, which are becoming increasingly highly integrated and densely packed, and whose heat generation tends to increase.

[Brief explanation of the drawing]

A characteristic diagram of a semiconductor device, FIG. 3 is a diagram of the relationship between the amount of crosstalk and thermal conductivity of the filler of the present invention, and FIG. 4 is a diagram of the relationship between the film thickness and thermal conductivity of the filler of the present invention. be. In the figure, 1 is a resin-sealed semiconductor device, 2 is a semiconductor element, 3 is a mounting part, 4 is a lead, and 5 is a bonding wire.
6 is a sealing resin, and 7 is a filler. An example of a blood-resistant sealed conductor device. 1 Space (h) Advantages of the present invention 11. /Oman i;l & L upper nail fat seal body value 19 years old 1 bamboo" η 2nd [! 1 Fan TA/Right η:L# amount (meeting (phantom present invention/ltT/vn's; 款Mai amount Hi and other Ibun guide prisons, between Figure 3)

Claims (1)

[Claims] A resin-encapsulated semiconductor characterized in that aluminum powder coated with an aluminum oxide film or an aluminum nitride film with a thickness of 0.5 to 20.0 μm is kneaded into a sealing resin as a filler. Device.