JPS5848926A - Insulated type semiconductor device - Google Patents

Abstract

PURPOSE:To realize ridid brazing with metal plate and obtain an insulated type semiconductor device with good thermal conductivity using inorganic insulated plate by sintering metal powder including Mo and W into the inorganic insulating material containing any one of the AlN or SiN groups as the main component under the reduction ambient and thereby providing a metallized layer. CONSTITUTION:The powder mixing Mo and W which well reacts with AlN or SiN plate 11 and rigidly adheres to them is mixed with the volatile organic medium and then printed, and such metal powder is kept at a temperature of 1,320 deg.C for 20min in the reduction gas ambient and then it is sintered, followed by non-electrolytic Ni plating 12. Thereafter, such element is kept at a temperature of 810 deg.C for about 5min under the H2 ambient. Succeedingly, the Cu plate 13, Si transistor pellet 14 are sequentially laminated and are bonded with the Pb-Sn system solder 15, the supporting plate 16 of Cu is bonded with the solder 17 of the same system, and finally these are sealed by the connecting lead L epoxy resin as specified. The insulated type semiconductor device according to this structure effectuates excellent heat radiation and insulation characteristics as well as excellent temperature proof cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an insulated semiconductor device, particularly #! - A semiconductor device in which a conductive base and a metal support on which a semiconductor substrate is placed are electrically insulated and thermally connected.

In a hybrid integrated circuit device equipped with a plurality of high-output transistors, which is an example of a semiconductor device, a flefter current of several amperes or more flows, and at this time, the transistor pellet as a semiconductor element usually generates heat. In order to avoid instability of characteristics and accelerated deterioration of life due to this heat generation, it is necessary to prevent the temperature of the transistor bellet from rising beyond the allowable limit temperature. Further, in many cases, circuit elements mounted on a hybrid integrated circuit device, especially transistor pellets as semiconductor elements, must be electrically insulated from other circuit elements. Furthermore, in hybrid integrated circuit devices that require advanced functionality, the mounted circuit elements are subject to external influences.
In particular, from the standpoint of safety and prevention of electromagnetic interference, the mounted circuit elements of a hybrid integrated circuit device must be electrically isolated from its storage container.

In order to meet these requirements, an insulating board is required that has excellent thermal conductivity and electrical insulation, and can mount circuit elements constituting a predetermined electric circuit in a limited space. As an example of such an insulating plate, as shown in the cross-sectional view shown in FIG. An insulating plate 3 is bonded through the insulating plate 2, and a lead layer is placed on the other side of the insulating plate 3.
A structure in which an electrode plate 5 such as a copper plate is bonded via a second metal solder 4 made of tin-based solder or the like is known, and the hybrid integrated circuit device further has a structure in which an electrode plate 5 such as a copper plate is bonded via a second metal solder 4 made of tin-based solder or the like. A circuit element such as a semiconductor substrate is integrated through a third metal solder made of a metal solder, and then predetermined electrical wiring and sealing treatments are performed. In a hybrid integrated circuit device having such a structure, it is desirable that the insulating plate 3 has excellent electrical insulation and high thermal conductivity, and from this point of view, inorganic insulating materials such as alumina and beryllia are often used. However, inorganic insulators other than alumina and beryllia, such as aluminum nitride and silicon nitride, have extremely excellent electrical insulation properties with a volume resistivity of 1014 Ω·m or more (at room temperature), and thermal conductivity of 0.2'1 m/m or more, respectively.・C・s, o, o
It has good thermal conductivity of 3*/C/S (at room temperature), and has desirable properties as an insulating board for semiconductor devices as described above. Nevertheless, these inorganic insulators have rarely been put to practical use in semiconductor devices. The reason for this is that, compared to alumina and beryllia, there is a lack of well-established methods for producing homogeneous and mass-produced products at a lower cost than in comparison to alumina and beryllia. This is partly due to the fact that it has been extremely difficult to realize this, that is, to perform highly reliable metallization on the surfaces of these inorganic insulators.

An object of the present invention is to provide an insulated semiconductor device with excellent thermal conductivity using the above-mentioned inorganic insulator.

An insulated semiconductor device of the present invention that achieves this object includes an inorganic insulating member that is supported by a supporting member and has at least one main plane on the side opposite to the supporting member, and a metal solder on the main plane of the insulating member. A semiconductor device comprising a metal plate bonded to a metal plate, and at least one semiconductor substrate conductively bonded to a surface of the metal plate opposite to an insulating member side, wherein the insulating member is made of aluminum nitride, boron nitride, nitride. It is a substance whose main component is one selected from the group of silicones, and a powdered metal containing molybdenum and tungsten is applied to the surface of the insulating member at least in the area where the metal plate is bonded using gold wax in a reducing atmosphere. characterized in that it has a metallized region comprising a metal layer sintered with.

To explain the present invention in more detail, the above-mentioned metallized region is formed by (1) printing a molybdenum and tungsten mixed powder that is highly reactive and has strong adhesive properties with aluminum nitride and silicon nitride as inorganic insulating members; At this time, the mixed powder was applied by printing the mixed powder paste, which was made into a paste by kneading it together with a volatile organic solvent, to a thickness of about 60 μm. The insulating member was heated at 1320C in a reducing forming gas atmosphere (hydrogen 1:nitrogen 10.capacity ratio).
(Holding time: 20 minutes) to volatilize the organic matter in the above-mentioned mixed powder paste and promote sintering of the powdered metals and reaction between the powdered metals and the inorganic insulator,
(3) Electroless nickel plating is applied to the sintered metal integrated with the inorganic insulator to form a nickel plating layer with a thickness of 3 to 5 μm, and the inorganic insulator with the nickel plating layer is then 81CI'((
(holding time: 3 to 5 minutes). Both surfaces of the inorganic insulator metallized in this manner are integrated with a metal plate such as a copper plate by a general method of applying lead-tin solder. One of the integrated metal plates serves as a support plate, and the other serves as a conductor plate on which a semiconductor substrate is mounted and a heat sink plate.

Hereinafter, the present invention will be explained in more detail using examples.

Example 1 In this embodiment, an insulated transistor will be explained.

FIG. 2 is a cross-sectional view of the insulated transistor obtained in Book J Biaoyu 11. This transistor consists of a laminated metal layer 12 consisting of a metal layer containing molybdenum and tungsten sintered and integrated on both sides of an aluminum nitride plate 11 as an inorganic insulating member, and a nickel layer plated on the metal layer.
A copper plate 13 as a conductor plate and a silicon transistor pellet 14 as a semiconductor substrate are sequentially laminated on one main surface side of this aluminum nitride plate 11 and conductively bonded with lead-tin solder 15, and the other side is It has a structure in which a steel plate 16 serving as a support plate is bonded to the main surface side using lead-tin solder 17. At this time, the emitter and base regions of the transistor bellet 14 are conductively connected to predetermined metal terminals via thin aluminum wires, the copper plate is conductively connected to a predetermined metal terminal (collector), and the transistor bellet 14, The copper plate 13, aluminum nitride plate 11, etc. are molded with epoxy resin so that they are completely sealed.

Bellet 1 of the isolated transistor obtained with the above configuration
The thermal resistance from 4 to the copper support plate 16 is 0.851T/
W and exhibits good heat dissipation, and the copper plate 13 and the copper support plate 1
Although an AC effective value voltage of 2000 V [50 Hz] was continuously applied for 10 hours during 6 hours, no dielectric breakdown occurred. Furthermore, the obtained insulated transistor was subjected to a temperature cycle of 155R (25 minutes) - room temperature (5 minutes) - +150C (25 minutes) - room temperature (5 minutes) 2000 times, but no change in thermal resistance was observed. Ta. In this way, an isolated transistor with excellent heat dissipation, insulation properties, and temperature cycle resistance was obtained because aluminum nitride can be metallized with a laminated metal layer with excellent adhesive strength, and it can be bonded to a metal plate. This is due to the fact that integration has become possible.

Example 2 In this example, silicon nitride plates were used as the inorganic insulating members in Example 1, and these inorganic insulating members were metallized with a laminated metal layer similar to that in Example 1. An isolated transistor was obtained.

The thermal resistance of the isolated transistor obtained with the above configuration is 1
．． It had good heat dissipation of 25 r/W, and its insulation properties and temperature cycle resistance were almost the same as in Example 1.

In this way, an isolated transistor with excellent heat dissipation, insulation properties, and temperature cycle resistance was obtained because silicon nitride could be metallized with a laminated metal, which has excellent adhesive strength. This is because it has become possible to integrate with

Embodiment 3 In this embodiment, a current control power module for a 10A class inverter will be taken as an example.

As shown in Figure 3, this power module is 70 mm x 140 mm x 3 with nickel plating on the bottom.
．． A 25 m aluminum support plate 21 with a thickness of 2 mm and metallized regions made of laminated metal layers similar to those in Example 1 were provided on both sides.
m x 25 m x 0.6 m aluminum nitride plate 221-2
26, the same (15mmX 15mmX016 aluminum nitride plate 227, 228 and the same
15mm x O, 6rran aluminum nitride plate 22
9 and 2 3mm with nickel plating on the surface
X 23mmX O, 25rrr! n aluminum mounting plates 231 to 236, same (13wnx 13ts x 0.
Aluminum mounting plates 237 and 238 of 25mm diameter and the same (14mm x 13mm x 0.25m aluminum mounting plate 239) were successively integrated via lead-tin solder (not shown) and placed on the aluminum mounting plate. A hybrid integrated circuit as shown in Figure 4 is constructed by mounting transistors, diodes, resistors, and bidirectional thyristors via lead-tin solder (not shown), and a sealing case made of epoxy resin. (not shown) and further filled the inside of the case with insulating resin to obtain a module.This module constitutes the electric circuit shown in Fig. 4, and the area indicated by the dashed line Each circuit element is mounted on a corresponding aluminum mounting plate.

Transistor of the module obtained with the above configuration.

It was confirmed that the thermal resistance between each pellet of the diode and bidirectional thyristor and the aluminum support plate was 0.6'C/W or less, and that it had excellent heat dissipation properties that would not cause any practical problems. Further, the same module was subjected to 50 temperature cycles similar to those in Example 1, but no change in thermal resistance was observed. Furthermore, the same AC pressure as in Example 1 was applied between the aluminum mounting plate and the aluminum support plate for 10 hours.
No dielectric breakdown was observed. As described above, since the heat dissipation is good, a large number of power elements that generate significant heat can be accommodated, and as a result, it has become possible to downsize the power circuit.

As explained above, according to the present invention, an insulated semiconductor device with excellent thermal conductivity can be obtained using an inorganic insulating plate made of aluminum nitride or silicon nitride. This is because it has been possible to metallize aluminum nitride and silicon nitride, which has been extremely difficult in the past.In other words, it is a laminated metal containing sintered molybdenum and tungsten that has excellent adhesive strength and can be bonded with metal solder such as solder. This is because the inorganic insulating plate can be made into a metal, making it possible to integrate it with a metal plate, etc. Further, according to the present invention, it is possible to use general printing and baking metallization methods for metallizing the inorganic insulating plate, and the metallized inorganic insulating plate can be subjected to reflow treatment using ordinary metal soldering. Since it can be integrated with a metal plate, it is easy to manufacture semiconductor devices.

In addition, in the present invention, the metal plate on which the semiconductor substrate is placed plays a main conductive path of the semiconductor device, and if the conductive path can be secured only with metal solder, the purpose of the present invention can be achieved even if the metal plate is omitted. It can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional insulated semiconductor device, FIG. 2 is a sectional view of an insulated transistor to which the present invention is applied, FIG. 3 is a perspective view of a power module to which the present invention is applied, and FIG. 4 is a sectional view of a conventional insulated semiconductor device. This is an electrical circuit of the power module shown in Figure 3. DESCRIPTION OF SYMBOLS 11... Aluminum nitride plate, 12... Sekichi metal layer, 13... Copper plate, 14... Silicon transistor Belen Figure 1 Figure 3 Figure 4 V 236 23η 232

Claims (1)

[Claims] 1. An inorganic insulating member supported by a support member and having at least one main plane on the opposite side of the support member side 2;
A metal plate bonded to the main plane of the insulating member by a metal solder, and at least one semiconductor substrate conductively bonded to a surface of the metal plate opposite to the insulating member side, The insulating member is made of a substance whose main component is one selected from the group of aluminum nitride and silicon nitride, and molybdenum and O:PNY are applied to at least the surface of the insulating member in the area where the metal plate is bonded by metal solder. An insulated semiconductor device comprising a metallized region including a metal layer formed by sintering powdered metal containing stainless steel in a reducing atmosphere. 2. An insulated semiconductor device according to claim 1, wherein the semiconductor substrate is electrically conductively bonded to the metallized region via a metal solder.