JPS59165447A - Integrated circuit - Google Patents

Abstract

PURPOSE:To obtain the integrated circuit comprising the thick-film resistor without a blister on surface of the substrate of insulating silicon carbide ceramic by using the conductive substance which is non-reactive to the silicon carbide ceramic and the material consisting of non-reducable glass as the materials of the thick-film resistor. CONSTITUTION:A thick-film resistor 3 consisting of the conductive substance which is non-reactive to the silicon carbide ceramic and the non-reducable glass is formed on surface of the insulating silicon carbide ceramic substrate 1. The components of this non-reducable glass comprise Gibbs' standard-producing free energy in 900 deg.C of about 49kcal/mol or less for each metal oxide in the molecule. The above conductive substance preferably consists of one or more of LaB6, MoB, YB6, CaB6, BaB6, Ta2O5 and In2O3 and the non-reducable glass preferably consists of one or more of CaO, ThO2, BeO, La2O3, SrO, MgO, Y2O3, the rare earth oxide, Sc2O3, BaO, HfO2, ZrO2, Al2O3, Li2O3, TiO, CeO2, TiO2, SiO2, B2O3, Cr2O3 and ZnO.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an integrated circuit using an electrically insulating silicon carbide ceramic substrate, and particularly a thick film hybrid integrated circuit suitable for mounting a high-power semiconductor element. Regarding.

[Background of the invention]

An integrated circuit has conductors, resistors, etc. on a ceramic substrate. Thick film hybrid integrated circuits are formed by forming these conductors and resistors by screen printing or baking techniques.

Alumina (At203''I), which is an oxide ceramic, has been used for ceramic substrates in integrated circuits.

However, recently, carbide ceramics such as silicon carbide (SiC) are being used instead of oxide ceramics. This fact can also be found in Japanese Patent Application Laid-Open No. 113683/1983.

The present invention was discovered in the process of researching a technique for directly forming a thick film resistor on the surface of an electrically insulating silicon carbide ceramic substrate. In other words, we discovered that when the thick film resistor material used for alumina substrates was used for silicon carbide ceramic substrates, blistering occurred in the thick film resistors, and we were considering countermeasures.

[Purpose of the invention]

An object of the present invention is to provide an integrated circuit having a thick film resistor without blisters on the surface of an electrically insulating silicon carbide ceramic substrate.

[Summary of the Invention] The present invention uses a non-reactive conductive substance and a non-reducing glass (each component corresponds to one metal-oxygen bond in the molecule) to silicon carbide ceramic as a material for a thick film resistor. Approximately -49Kca
It is characterized by using a material having a standard Kipus free energy of formation at 900C of less than t/mot.

The composition ratio of the conductive substance and non-reducing glass is determined by the target resistance value of the thick film resistor. If high resistance is desired, the amount of non-reducing glass may be increased, and if low resistance is desired, the amount of conductive material may be increased. Considering the adhesion of the thick film resistor to the silicon carbide ceramic substrate, the amount of non-reducible glass is at least 5% by weight.
It is desirable to set the above. Generally, conductive material 10
It is desirable to choose within the range of 95% by weight with the remainder being non-reducible glass.

When a thick film resistor used for an alumina ceramic substrate is used for a silicon carbide ceramic substrate,
The reason why bulges occur in thick film resistors is as follows.

The thick film resistor on the alumina substrate uses RII as the conductive material.
02. Since PbO and the like are used as glass materials, explanation will be given by taking these as examples.

Note that in the present invention, the electrically insulating silicon carbide ceramic substrate does not mean that it has no conductivity at all.

This means that it has enough electrical insulation to be used as a substrate for integrated circuits.

The technology of the present invention can be widely applied to silicon carbide ceramics in general.

Since Ru 02 is a highly reducing metal oxide, when a thick film resistor using Ru 02 as a conductive substance is fired on a SiC substrate, the reaction shown in equation (1) occurs.

8iC+3/2RL102 →5iOz+3/2Ru+
CO↑・(1) On the other hand, since PbO is also a highly reducing metal oxide, the reaction shown in formula (2) occurs similarly to formula (I).

sic+3Pbo→5i02+3Pb+CO↑ ・・
- (2) The CO gas generated by these reactions causes blistering in the resistor film.

Generally, when the reaction between SiC and a metal oxide (assumed to be MO) is assumed to be as shown in equation (3), whether or not the reaction shown in equation (3) occurs is determined by the formation free energy of this reaction (
(expressed as ΔG).

8 i C+ 3M0-+8 i 02 + 3M+
CO↑ ... (3) The condition for the reaction shown in equation (3) to occur is that ΔG at the firing temperature is positive, and ΔG at the temperature is as shown in equations (4) and (5). Become.

ΔG-(ΔG'5lo2+3ΔG'M+ΔG'(o)-
4ΔG; Io+3ΔG'Mo)〉O・・・・・・・・・
(4) If the thick film resistor is made of a metal oxide having a standard formation free energy value that satisfies the above equation (5), the reaction shown in equation (3) will not occur during firing, It is possible to obtain a good thick film resistor without blistering of the resistor film or chemical change of the resistor material. However, formula (4).

ΔGO8IC in equation (5) is sic at a given temperature
shows the standard free energy of formation value. Similarly, ΔG0O represents the standard free energy of formation of metal oxide MO at a predetermined temperature. The same applies to others.

The normal firing temperature for glass made of non-reducible oxides is 90°C.
It should be around 0C, 9. (5 at 1200'K)
) Calculating the condition of the formula, Δo;o < −48,7K
cat/mot or less than about -49Kcat/motfx. Non-reducible metal oxides that satisfy this value of ΔGoMo are shown below. In addition, 1200'K is in parentheses.
ΔG'M□ (Kc
al/mot) values are shown.

Cab (-121), That (-119), Bed
(-115), Lat, s (-115), 5ro(-
113), Mg0(-itz), Y2O3(-txt
), rare earth oxide (-n.

~-108), 5C203 (107), Bad (-10
6).

Hf0z (105), Zr02 (103), Atze
3 (103), Ljz03 (-103), Tie (-9
7), Ce02(92L T'i0□(-87L 5i
02 (-80), B2O3(78LCrzOs (-
65>, Zn0 (53).

On the other hand, typical reducing metal oxides include the following. 5n02(40'l, Mn0z(313).

K2O(37), N1p(-33), Cd0(-2
8), Pb0 (24), Bi20g (19),
CLIO (13'), Ru02 (4). These reducing metal oxides are thought to cause the reaction shown in equation (3), and are not preferred as a composition for a thick film resistor directly formed on a SiC substrate.

Therefore, the conductive material of the thick film resistor formed directly on the SiC substrate is LaB6, which does not react with silicon carbide ceramic.
, MOB, YB6. CaB6. BaBs l5rBa
Non-oxides such as 'l'a205, InzOa
Non-reducible metal oxides such as the following are suitable, and the above-mentioned non-reducible metal oxides are suitable as the glass component.

[Embodiments of the invention]

Example 1 A glass paste shown in Table 1 was formed by firing on an electrically insulating silicon carbide ceramic substrate. House 1 is made of non-reducing glass, and House 2 and A3 are made of reducing glass.

The paste using non-reducing glass did not cause blistering, but A2 and Ya3 using reducing glass had a severe bubbling phenomenon and the paste blistered.

Example 2 A mixture of glass and conductive material shown in Table 1 was formed on an electrically insulating silicon carbide ceramic substrate by firing to obtain a thick film resistor. Table 2 shows the composition ratio of the mixture and the presence or absence of foaming. In case (2), there was no foaming phenomenon and no blistering was observed, but in cases (2) and (2), severe bubbling phenomenon and blistering were observed.

Table 2 Example 3 An example will be explained with reference to FIG. L a used here
The composition of the Bg-based resistance paste is as follows.

LaBc+ resistance paste component: LaBa 20% by weight.

50% glass, 30% vehicle.

Glass composition: B2O325, 9% by weight + s 1Q2
40.8 weight'l=, , AtzOs I J3.8
Weight s, Ca0 10.3% by weight l zro, 3.
6% by weight, Tie, 0.6% by weight.

High thermal conductivity (2.7W/cm-1Z')'ft made electrically insulating by controlling the grain boundaries with Betium oxide.
On the upper surface of the SiC substrate, an Au-based thick-film conductor 2a was formed as a resistance terminal, and a LaB-based thick-film resistor 3 was formed between these terminals, and then an Ag/Pd-based thick-film conductor 2 was formed. Furthermore, a high power transistor (collector loss IW) 4 was connected to the thick film conductor 2 using a Pb80/5n20 solder 5, and the base and emitter terminals were connected to the thick film conductor 2 using an aluminum wire 6.

Furthermore, electronic components such as capacitors (not shown) were mounted to form a thick film hybrid integrated circuit.

The temperature rise on the top surface of the semiconductor element during operation of the hybrid integrated circuit of this example was measured, and compared with that of a hybrid integrated circuit according to the prior art shown in FIG. 2, which was formed in the same way using the same semiconductor on an alumina substrate. As a result, the temperature rise in this example was #) 3c lower than in the conventional example. In addition, the area (substrate area) of the hybrid integrated circuit of this example was able to be reduced by about 20% compared to the conventional example. .3 w/cm = c)
Therefore, when connecting a semiconductor element, it is necessary to bond a metal heat sink to the conductor 2 in advance and connect the semiconductor element through the heat sink, but the present invention has the effect that the metal heat sink can be omitted. .

In FIG. 2, numeral 7 is an alumina substrate, and 8 is a metal heat sink.

Embodiment 4 FIG. 3 is an embodiment of a thick film hybrid integrated circuit using the same SiC substrate as in Embodiment 3 and mounting a high-power semiconductor IC.

After forming the Au-based thick film conductor 2a on the substrate l, the L a B s-based thick film resistor 3 and the A g/
A Pd-based thick film resistor 2 was formed.

Next, the semiconductor ICl0 is stacked on the conductor 2, and the AIJ-8
An i-eutectic 9 was formed and connected, and the terminal of the IC was connected to the conductor 2a through the A and U wires 6.

The same heat dissipation effect as in Example 3 was also obtained in the thick film hybrid integrated circuit of this example. Furthermore, since the thick film resistor in Example 4 can also be directly formed with high thermal conductivity 5iCK, the area of the thick film resistor can be reduced, which is effective in reducing the substrate area.

As described above in detail regarding the embodiments, according to the present invention,
In addition to preventing thick film resistors from blistering, SiC has extremely high thermal conductivity.
By using a ceramic substrate, υ high-power semiconductor devices can be mounted directly on the substrate without attaching a metal plate for heat dissipation.
Furthermore, since thick film conductors and thick film resistors can be formed directly on the SiC substrate, there is a great effect on downsizing of thick film hybrid integrated circuits.

〔Effect of the invention〕

As described above, according to the present invention, when a thick film conductor is directly formed on an electrically insulating silicon carbide ceramic substrate, it is possible to prevent blisters from forming in the thick film conductor.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a thick film hybrid integrated circuit according to an embodiment of the present invention, FIG. 2 is a sectional view of a conventional thick film hybrid integrated circuit having a high power semiconductor element, and FIG. 3 is a sectional view of a thick film hybrid integrated circuit according to an embodiment of the present invention. FIG. 7 is a cross-sectional view of a thick film hybrid integrated circuit according to another embodiment.

Claims (1)

[Claims] 1. On the surface of an electrically insulating silicon carbide ceramic substrate, a conductive substance that is non-reactive with the silicon carbide ceramic and a non-reducing glass (each component is a metal-oxygen bond in the molecule) An integrated circuit characterized in that it has a thick film resistor having a typical free energy of formation of a cast at 900C of less than about -49 Kcal/mol per piece. 2. In claim 1, the conductive material is LaB5, MOB, YB6, CaBs,
BaBa. An integrated circuit comprising at least one selected from the group consisting of 8rBs + Ta205 + In2O3. 3. In claim 1, the non-reducing glass is Cab, Tb02t Bed, La2O5,
sro. MgO, Y2O3, rare earth oxide + 8czOs +
BaQ. Hf 02 r Z r02 + AZ203+ L
i20g '+ T' 0 * CeOz TTiO
z, 8i0z, B2O3, cr2o3, Z
An integrated circuit comprising at least one selected from the group consisting of nO and cy.