JPH027445A - Aluminum nitride substrate, its manufacture and semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for metallizing aluminum nitride, and particularly relates to a method for metallizing aluminum nitride, and uses 'i1, which is a strong metal with an insulating characteristic suitable for mounting power semiconductor devices. [Prior art] Regarding an insulating substrate, a method for manufacturing the same, and a semiconductor device using the same, a conventional method for metallizing the surface of non-oxide ceramics such as aluminum nitride is disclosed in Japanese Patent Application Laid-open No. 53-1023.
As in No. 10, in advance, A403-S i 0
After forming a metal oxide like 2, Mo-M
There is a method of printing and sintering a paste containing N powder, or as proposed in Japanese Patent Application Laid-open No. 59-40404 or No. 61-26231, the surface of aluminum nitride is oxidized at high temperature to form A403 -. The metal plates were directly bonded by heat, or the metal layer was formed via a eutectic layer of metal oxide.

[Problem to be solved by the invention]

The common point in all of the above conventional methods is that A4403-8
0 Snow or Ago, etc. oxidation IN! -. This has the problem that the process becomes 1M more complicated than the metallization method of ordinary oxide ceramics such as alumina, which increases the manufacturing cost, and also reduces the insulation properties of the ceramic surface.

In other words, although forming an oxide layer on the surface of aluminum nitride is effective in improving the wettability with the metal layer to be formed subsequently, the prior art does not mention the difference in thermal expansion coefficient between aluminum nitride and the oxide layer. It has not been.

Although an oxide pattern is formed on the surface of aluminum nitride due to the high-a treatment at 1000° C. or higher, the electrical insulation properties are poorer than that of the usual oxides such as alumina. Also,
Due to poor thickness uniformity and reproducibility, it is not possible to maintain the uniform oxidation depth of 5 to 7 μm as disclosed in the above-mentioned publications. This causes deterioration of the surface insulation properties. Therefore, semiconductor devices using round-windowed aluminum with oxidized layers often experience failures such as short circuits during various reliability tests such as high-temperature reverse bias tests, preload tests, and thermal cycle tests. It had become.

On the other hand, one of the reasons why Mo can be sintered onto the surface of general alumina is said to be that additives in the paste and impurities in the alumina become vitrified through mutual diffusion and wet the Mo surface. However, since aluminum nitride is characterized by high purity, impurities from the ceramic side cannot be expected.

Therefore, in the conventional method, ATOs or ATOs
1 such as -8i 01 is formed first, and it is expected that a vitrification reaction will occur between the additives in the paste, but in this case, high temperatures are required for sintering, and the surface of A disadvantage has arisen in that oxidation progresses.

An object of the present invention is to provide an aluminum nitride substrate on which a strong metal layer suitable for mounting a power semiconductor device is formed and which has good insulation properties, a method for manufacturing the same, and a semiconductor device for its use.

[Means to solve the problem]

To summarize the present invention, the first invention of the present invention relates to an aluminum nitride substrate, in which at least a part of the substrate surface is covered with a metal 71 to which a semiconductor chip can be connected using a brazing material. At least a portion of the aluminum nitride substrate surface is made of Mo, MnO and 510
It is characterized in that its surface is covered with a brazable high-melting point metal layer, with or without intervening a layer consisting of 2 and an intermediate layer.

A second invention of the present invention is an invention relating to a method for manufacturing an aluminum nitride substrate, the method for manufacturing an aluminum nitride substrate in which at least a portion of the substrate surface is covered with a metal layer to which a semiconductor chip can be connected using a brazing material. , on at least a portion of the surface of the aluminum nitride substrate, a weight ratio of 80 to 95
% Mo% 5-11j% MnO1 and 5-9% S
A paste containing iO2 or the MnO and 8i0
．． a step of applying a paste containing Mo and glass powder in the weight ratio previously vitrified, 1200-1
It is characterized by including the steps of sintering at 550° C. and forming a brazable high-melting point metal layer as a surface layer above the sintering step.

Furthermore, a fifth invention of the present invention relates to an insulated semiconductor device, and the insulated semiconductor device has a structure in which a semiconductor chip, an aluminum nitride substrate, and a metal heat sink are connected to each other via a brazing material. , the aluminum nitride substrate is the aluminum nitride substrate of the first aspect of the invention.

MnO and Sin in the paste react to form MnO-8iO1 glass during the sintering process. In this state, the viscosity is kept low and Mo is liquefied, so the surface of aluminum nitride and Mo are wetted and a strong bond is possible. However, Mo1MnO1S10! Alternatively, when organic substances such as vehicle μ are mixed alone, it is difficult for the vitrification reaction to occur uniformly, resulting in variations in adhesive strength, and metals and I! It also oxidizes aluminum nitride in the vicinity of 1, causing insulation defects.

Therefore, MnO and 810. If Mo is vitrified or compounded in advance, there will be no variation in the sintered state of Mo, and the yield of the layer and adhesive strength will be improved.

In the aluminum nitride substrate of the present invention, at least a portion of the main surface of the aluminum nitride substrate is made of K, Mo, MnO.
and Sin. l! 1 may be present, and another component layer may be present above and/or below it. Examples of brazable high melting point metals present on the surface include N1 and Au.

Thus, as an example of an aluminum nitride substrate, the covering layer is a first region of MnO-A/40B compound.

A second region 4t in which Mo and MnO-SiO2 glass or a compound are mixed, and an N1 surface layer, and the first region 4t in which the ff1 layer is a mixture of Mo and MnO-SiO2 glass, Mo and a second region made of a metal compound of N1, and a surface layer of N1.

In addition, as a specific example of the manufacturing method of these aluminum nitride substrates, the process from applying the paste to sintering described above in the method of the present invention is the process of printing and applying the paste on the aluminum nitride substrate surface, and then A step of decomposing and scattering organic components by holding at 300 to 400°C for up to 1 hour in a forming gas of hydrogen and nitrogen containing A process of improving the wettability of MnO and 5ift necessary for connection or its glass body, followed by a process of 1200~1 in dry hydrogen and nitrogen forming gas.
Some include each step of sintering at 550°C.

The aluminum nitride substrate of the present invention obtained as described above is incorporated into a semiconductor device by a conventional method to provide a layer, for example, a semiconductor device of the present invention with good insulation properties.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples.

Example 1 FIGS. 1 and 2 are diagrams showing an example of the blending ratio of Mo paste necessary for metallizing the surface of an aluminum nitride substrate according to the present invention. Among these three substances, Mo has a high melting point and is difficult to react with, so it does not react directly with aluminum nitride, but it does not react directly with MnO! As shown in Figure 2 by the relationship between component ratio (horizontal axis) and liquefaction temperature (°C1 vertical axis), MnO is 64% and 810% by weight! The technology of the present invention for connecting Mo to the surface of an aluminum nitride substrate, which liquefies at 1250°C in a limited region of 36%, uses the above-mentioned fact. MnO and 810 inside! Or M in advance
A powder obtained by vitrifying nO and 8108 may be mixed.

Mo, MnO and S10! The mixing ratio is M in direct %.

It is sufficient if the range is within the hatched area shown in FIG. 1, where the MnO content is 80 to 95X, the MnO content is 15 to 11X%5ins is 5 to 9%. If the ratio of MnO and SiO2 exceeds the above ratio, it is undesirable because as shown in FIG. 2, the layer with a high liquefaction temperature and the sintering temperature of the Mo paste will rise and the aluminum nitride surface will be abnormally oxidized.

Figure 3 also shows Mo and MnO5BLO2 or Mn
It is a diagram for explaining the appropriate mixing ratio of glass powder consisting of O and sio, and shows the glass component amount (weight t%, horizontal axis).
, specific resistance P (μΩ・country, vertical@) and tensile strength (k
g/w? , vertical axis).

First, focusing on the specific resistance after Mo sintering, M.

The glass component consisting of MnO and Sin or MnO and Sin mixed in the glass is less than 5% by weight, or 20
%, the resistance value increases rapidly. On the other hand, when looking at the tensile strength, contrary to the resistance curve, a significant decrease in strength is observed when the amount of the glass component is less than 5% or more than 20% in terms of weight t%.

The reason why the resistance value is large in the region where the glass component ratio is 5% or less and the tensile strength decreases is that when the glass component, which plays an important role in connecting the aluminum nitride substrate and Mo, is small, Mo sintering occurs. This is because the amount of glass component does not progress sufficiently.The reason why the resistance value increases in the range where the amount of the glass component exceeds 20% is because there is a large amount of glass component and it has reached the surface of Mo. If it exceeds 20%, the subsequent N1 adhesion is poor and the peel strength at the Mo-N1 interface is also low. From the above results, M to Mo Benuto
nO and sio or MnO and 810! It was experimentally clarified that the amount of glass powder added should be within the range of 5 to 20% by weight.

FIG. 4 is a diagram illustrating the sintering method of the Mo paste in terms of the relationship between time (horizontal axis) and temperature (vertical axis).

When applying Mo paste to aluminum nitride and sintering it, it is ideally desirable to perform the process in a reducing atmosphere to prevent oxidation of the substrate surface and the Mo surface. but,
In this case, the organic matter in the Mo paste remains as carbon, and this is the inorganic component Mo, MnO1S that makes up the metal layer.
In! 810. reacts with MnO to form respective carbides. Sintering becomes difficult because it inhibits the vitrification reaction. Further, on the aluminum nitride surface which does not require a metallized film, this carbon causes a reduction in insulation properties due to its strong reducing action. On the other hand, in order to avoid these problems, if we use the general gold 4 method for alumina substrates, which involves sintering in a humid atmosphere and then reducing the Mo surface,
Problems such as thick oxidation was formed on the surface of aluminum nitride and cracks were observed in the oxidation due to the difference in thermal expansion coefficient between aluminum nitride and 1llI oxide (α-ATOs). In view of the above, the present inventors have experimentally discovered a sintering method that can sufficiently thermally decompose and scatter the organic carbon in the Mo paste to form a strong Mo metallization. FIG. 4 is an example.

The aluminum nitride substrate printed with Mo paste is 1
# Insert into a shallow slit cut on the surface of a large object, set it so that the surface is fully exposed to the atmosphere in the furnace, and insert it into the furnace. The sintering profile follows as follows, first,
Raise the temperature to 200-400'Q and hold for 30-60 minutes.
Figure 4: Thermal decomposition and scattering of organic components in paste
area and the ■ area that promotes vitrification, slightly oxidizes the Mo surface, and improves glass wetting. However, this area is heated to a maximum of 900°C to prevent oxidation of the aluminum nitride surface, and up to this point it is not moistened. A mixed gas atmosphere of hydrogen and nitrogen is used. Area ■ increases to 1250-135°C and 3
MnO
and Sin, or their vitrified powders are liquefied between this time and wet the surfaces of Mo and aluminum nitride,
It solidifies when the temperature falls, and aluminum nitride and Mo adhere to each other.

If the sintering method described above is followed, a strong molybdenum layer can be formed on the surface of aluminum nitride without generating oxidation.

FIG. 5 is a diagram illustrating the cross-sectional structure of a sample obtained by baking the Mo paste described above onto the surface of aluminum nitride using the sintering method described above.

The organic components in the Mo paste printed and coated on the aluminum nitride substrate 10 are thermally decomposed and scattered during the heating process of the sintering profile described above. Mo and MnO1S10! Alternatively, the lath powder is made of MnO and Sin, but in the subsequent temperature raising process, in the case of MnO and SiO2, it undergoes a vitrification reaction and liquefies, and if a powder that has been vitrified with MnO and SiO2 is used, it liquefies and is heated. It wets the surface of Mo oxidized in the hot process, fills the inside of the grain boundaries, and wets the surface of the aluminum nitride substrate.
When the glass 12 consisting of
and aluminum nitride. On the other hand, at this time, the surface of aluminum nitride was wetted with a glass consisting of MnO and SiO2, and a very thin layer 113 of KMnO-AI403 was formed during the temperature rise due to a vitrification reaction with α-A40m formed slightly during the heating process. Part of the very surface of Mo is still M
Mo3Si is formed from a glass made of nO and sio. All of these can be determined by x#1 diffraction.

As explained above, in order to apply the aluminum nitride substrate whose surface is metallized with Mog as a substrate on which an actual semiconductor chip is mounted, soldering or silver brazing is required. None (1 to 5 μm using the solving method, etc.)
An aluminum nitride substrate with a strong bonding surface can be obtained by forming a N1 layer, heat-treating it at a temperature range of 400 to 900° C., and diffusing a portion of the N1 layer into the Mo grain boundaries.

Example 2 Hereinafter, one example of a rush current according to the present invention will be explained with reference to the drawings.

FIG. 6 is a process diagram illustrating an example of the pear method for producing an insulating substrate according to the present invention.

(1) The Mo paste of the present invention is applied and patterned onto aluminum nitride ceramics by a printing method or the like.

The above-mentioned ceramics patterned with 121Mo have a temperature of 1300 to 1500' in a mixed gas atmosphere of hydrogen and nitrogen.
Heat to a temperature within the range of C to bake Mo onto the ceramic surface.

[3] After Mo sintering, the oxide layer on the Mo surface and stains on the ceramic surface are removed by immersing it in 5 to 20% by volume hydrochloric acid or nitric acid aqueous solution.

(4) Activate the Mo surface by immersing it in an acidic, platinum-based catalyst for 1 to 5 minutes.

(5) Immerse in medium-injected non-arousing nickel μ plating solution to obtain the desired thickness.

(6) It is heated in a hydrogen atmosphere at a temperature within the range of 400 to qaa° C. to perform a diffusion treatment of nickel during Mo deposition.

One example of the insulating substrate of the present invention can be formed by the method described above, but the process described in Section 1 (6) may alter the quality of the nickel surface and cause poor wetting during subsequent soldering. (Processes 71 and 81 may be added.) (7) Immerse in a 5 to 20 volume % hydrochloric acid or nitric acid aqueous solution to remove the very surface of the nickel.

(8) Immerse in neutral electroless nickel A/liquid, and
I/It forms the worst nickel in history.

By employing the above process, a strong and highly reliable metallization can be obtained on the surface of aluminum nitride, and an insulating substrate according to the present invention can be formed.

Next, the Mo paste according to the *invention will be explained using Table 1.

1@1 to 12 add MnO as raw additive, and further add 5
810. with iO1 as second additive. is blended. In addition, among these, in N19-12, a part of Mo was W
is replaced with On the other hand, Ugly 13 is a layer to which only MnO is added, and N1114 to 19 are examples to which oxides other than MnO are added. These pastes were sintered on the surface of aluminum nitride ceramics at 1300 to 1400'C using the process explained in Figure 6 above, plated with Ni, and then leaded with solder. 12, 13, and 1B, it can be seen that the Mo and aluminum nitride surfaces are bonded, although there are differences in strength. However, MnO
N1115 and CaO1Sin added only, Kuugi 14 and 17 or Al4o3, CaO added 9N
116.19 easily peels off in the initial tape peel test and cannot be bonded at this temperature. 'Wait M
The fact that N113 with MnO added to the aluminum nitride cannot be bonded to the surface of aluminum nitride even though it is an oxide compound containing MnO is presumed to be because the surface does not vitrify and does not wet the N0 grains. be done. This is because the other ugliness 14, 16, 17, 19, etc. are due to the same reason.

On the other hand, Taki 1 to 12 and ? which were able to fix aluminum nitride ceramic KMo grains. &L15.18 also shows a difference in adhesive strength. These will be explained with reference to FIGS. 7, 8, and 9.

Figure 7 shows the lowest temperature for MnO and Sin, 1250'c.
t (11%, horizontal axis) and tensile force υ of Mo when only Mo is changed at the vitrification ratio (64:36% by weight) in the vicinity
It is a graph showing the relationship between the strength (Jf, vertical axis) and the area resistance of Mo thickness (mΩ/mouth, vertical axis). This strength and area resistance value vary significantly depending on the Mo sintering temperature, but considering the low temperature sintering of around 1400°C, which is the purpose of the present invention, when the MoO amount is 80% by weight or more, the fracture location is Mo and nitriding. Since there are many variations in the interface bonding of aluminum ceramics and the sheet resistance is extremely small, it can be said that the amount of vitrification is too small to be in the r4 range where bonding is impossible. - Ho, M
If the amount of o is less than 70% by market weight, the solder will fail, and the power semiconductor device, which is the object of the present invention, will be used in a region where the bonding strength does not change in appearance but the sheet resistance value increases rapidly. The electrical resistance of the surface of the aluminum nitride ceramic to be mounted is high, and the subsequent process N1
It is not suitable in terms of the removal of metsukikan. The rim layer is considered to be an area where glass becomes excessive and the entire Vo layer is covered with glass. Therefore, the amount of glass component MnO-8102 for fixing Mo to aluminum nitride is 20
It is sufficient if it is within the range of ~30% by direct observation.

On the other hand, Figure 'a8 shows the glass components MnO and Si in Figure 7 above.
It is a graph showing the relationship between the amount of Sin (weight %, horizontal axis) and the tensile strength (in kg, vertical axis) when the ratio of n is changed. Subtract from this diagram! The highest strength is Mn.
O and 810. The ratio is 64:56% for severe failure, and the other parts are peeled off at the interface between Mo and aluminum nitride, and variations in strength are observed.

The nail layer, the part with the highest tensile strength, is MnO and 810!
This is a region with a minimum liquidus temperature of 1250° C., which means that glass is deeply involved in fixing Mo grains to the surface of aluminum nitride sepumics.

Nine, NLL9.112 in Table 1 above is a part of Mo
However, the amount of W is 15% compared to Mo.
Tensile strength tends to be low in the range exceeding % by weight. The reason for this is presumed to be the difference in wettability between W and glass.

Therefore, the composition ratio of the inorganic components in the Mo paste to the high purity aluminum nitride is 810. When the weight ratio of MoO is around 64 to 36, which indicates the lowest liquidus temperature, and is within the range shown in Figure 9 where 20 to 30% of Mo is added to Mo, the amount of MoO in the final layer is 70 to 80
, 12.5-20% by weight of MnO, 810. is 5-12
．． It is sufficient if it is 5% by weight.

Further, the amount of W used for improving the coefficient of thermal expansion of the Mo sliding door is preferably within 10% by weight of MoK.

Next, Ni@ on the sintered metallization 1 will be explained. Until now, when KNill was formed on sintered metallization 1 by a plating method, etc., and leads were attached and stretched with solder to this, it was often observed that the N1 layer would peel off at the interface between the N1 layer and sintered metallization 1. These reasons are that the surface of Mo is oxidized during the sintering process of metallization 1, and that Mo and N
This is because the binding force of 1 is weak. The present invention also addresses these drawbacks. As shown in FIG. 6, the surface of the Mo layer after sintering is removed by etching with 1% volume of 5-20% hydrochloric acid or nitric acid, and Ni II! i!
and then yI in a hydrogen atmosphere at a temperature of 500-900°C such that Ni enters the desired depth of the sintered metallized layer.
Just do p::S. By applying the above 9 & process, the peeling at the interface between the sintered metallization 'll and the N1 film will not be observed, and insulation defects between the metallization layers due to aluminum nitride surface contamination during the sintering process can also be prevented.

Semiconductor vit1 suitable for the present invention according to Fig. 10! The cross-sectional structure of the aluminum nitride substrate for mounting will be explained.

When a metallization paste is applied to the aluminum nitride substrate 10 by a printing method or the like and is sintered, a-kL snow OH 27 is formed on the surface of the aluminum nitride.

On the other hand, 810g of MnO, an additive in the metallization paste, or a MnO-Sing compound in the metallization paste 1C under metallization 1 undergoes a vitrification reaction, or the additive MnO-
When using a Gagus frit of 8iO, it softens and becomes A40s with MnO diffused in a-At and 03.
1v[nO mixed j-th and second regions 21 and 2
2 is formed. Further, this MnO-810B glass forms a part of Mo t-nulla L, a third region 23 in which Mo and MnO-Sing glass are mixed, and on the top thereof, Mo and additives 810. reacts and generates Mo1
A fourth region 24 containing a mixture of Si and Mo is formed.

Form Ni@ on such a sintered metallized layer and heat 9
& treatment, N1 diffuses into a part of the area where Mo and Mo1Si are mixed, and Ni, Mo, Mob
There is a fifth region 23 in which S i is mixed, and a sixth region 26 in which only N1 is present on the outermost surface.

Example 3 An example of the aluminum nitride substrate of the present invention was manufactured by a method similar to that described in the previous example, and a cross-sectional view of the dried substrate is shown in FIG. In FIG. 11, reference numeral 10 is an aluminum nitride substrate, 31 is a first region in which Mo and MnO-810g glass are mixed, 32 is a second region made of a metal compound of Mo and N1, and 33 is an N1 means the third region consisting of the surface, 1;

Example 4 An example of manufacturing a semiconductor device of the present invention is shown below as a process diagram in FIG. 12.

MoW baked by binder MnO-Sing
Place the pre-soldered semiconductor chip 40 on the main surface of the aluminum nitride chip 41 on which N1-, which can be soldered, is formed, and heat it to re-melt it to connect the aluminum nitride chip 41 and the semiconductor chip 4) The structure shall be as shown in section. Next, solder 42, which is made of a material that melts at a lower temperature than the previous solder, is pre-soldered to the other main surface of the aluminum nitride chip on which this semiconductor chip is mounted. AI heat sink 4
4 Set on top. At this time, a bonding bat 43 that has been pre-soldered in advance on the aluminum nitride surface on the side on which the semiconductor chip 40 is mounted is also set, which will serve as the collector terminal for a transistor and the anode terminal for a thyristor. Thereafter, this is heated and remelted, and the aluminum nitride chip with the semiconductor chip mounted thereon is connected to the metal heat sink, and the bonding butt is connected to the aluminum nitride chip to obtain the desired power semiconductor device structure shown in item 8). . Next, a pre-formed hybrid integrated circuit board 45 is adhered to a part of the metal heat sink, and the power semiconductor device portion and the hybrid integrated circuit portion are connected using wires such as aluminum.

The above describes the method of manufacturing a semiconductor device using an aluminum nitride substrate having a metal layer according to the present invention.

Next, MnO and S10 were added to the Mo'41 binder formed on the aluminum nitride chip on which the semiconductor chip was to be mounted.
! The advantages of using glass consisting of the following will be explained with reference to FIG. This figure shows 150℃ 25 minutes, room temperature 5 minutes, -
The above-mentioned sample was left in a tank set to test conditions where one cycle μ was 55°C for 25 minutes, and when the predetermined number of cycles I'v was reached, it was pulled out and the change in thermal resistance was measured using -II beta. The results are expressed as thermal resistance (”/W, vertical axis) and number of cycles (11!1d
It is a graph shown in relation to 1).

In Fig. 13, ■ indicates the case where a conventionally known aluminum nitride surface metallization method such as Japanese Patent Publication No. 53-102310 is used;
is the subject of the present invention.

The figure shows that the thermal resistance of a semiconductor device using an aluminum nitride chip metallized by a conventionally known method increases after 500 to 700 cycles. 20 in case ■
Even with 00 cycles, there was an increase of about 10%.

In addition, Figure 14 shows that a semiconductor device with a structure in which high voltage terminals are formed adjacent to each other on the surface of aluminum nitride, which is different from the semiconductor device analog structure shown above, was assembled and left under the test conditions described above. 12 is a graph showing the results of examining the insulation characteristics in the case of the present invention in terms of the relationship between the insulation characteristics Rfl (Ω, vertical axis) and the number of cycles (Ill axis).

In this case as well, in case (2) using the conventionally known method, the insulation properties deteriorated in the region exceeding 500 to 700 cycles, similar to the results of the previous investigation of changes in thermal resistance, but with the method (2) of the present invention
No change is seen at all.

We investigated a semiconductor device using an aluminum nitride chip metallized by a conventionally known method, which deteriorated its thermal resistance and insulation properties. An example of such a conventional semiconductor device is shown in Figure @15 as a schematic cross-sectional view. In FIG. 15, reference numeral 50 is AtN ceramic, 51 is oxide intermediate 52 is M
o-Mn, @, 53 is Ni, ld, 54 is solder-, 5
5 is a metal heat sink, 56 is a lead, 57 is a semiconductor chip,
5B means a failure location.

As is clear from FIG. 15, cracks and peeling are observed on the aluminum nitride surface near the surface of the aluminum nitride without baked Mo, 14 or adjacent metal. Considering the cause of this from the perspective of the conventional metallization process, we find that in the conventional method, the surface of the nitrided aluminum to miniram is oxidized in advance, and then Mo-Mn paste is applied and sintered again. A thick oxide film such as AAtOs, Al2
O, -8iO, A40B-8i01-MnO, etc. are formed. All of these factors are thought to be different from the thermal expansion coefficient of the underlying aluminum nitride, which is
It can be said that it was not able to withstand the stress of the heat cycle test mentioned above, which caused cracks and flaking.

On the other hand, the aluminum nitride chip used in the present invention does not need to oxidize the aluminum nitride surface, which is a layer different from the conventional metallization method, and the glass 1 of MnO-Sing as a binder has a thickness of 1 to 5 μm or less. One of its characteristics is that it is thin. Therefore, even if the coefficient of thermal expansion of the glass 1 made of MnO-Sing does not match slightly, there is an advantage that cracks and ants do not occur.

〔Effect of the invention〕

According to the present invention, since a sintered MetaTwisted layer can be formed on an aluminum nitride substrate at a low temperature, no abnormal growth of alumina is observed in the portion to be metasized, and the ceramic substrate has good insulation properties and can be used as a ceramic substrate for mounting semiconductor devices. It is also effective as a ceramic material for computer mounting, which requires a material with good release characteristics, and can also be used as an airtight sealing material because cracks do not occur in the alumina part due to the above-mentioned reasons.

[Brief explanation of the drawing]

@Figures 1 to 3 are diagrams explaining an example of the amount of components of the Mo paste used in the present invention, Figure 4 is a diagram explaining the conditions of an example of the sintering method of the Mo paste in the present invention, @5 The figure is a cross-sectional structural diagram of a sample in which Mo paste according to the present invention is baked on the surface of aluminum nitride, Figure 6 is a process diagram of an example of the method of the present invention, and Figure 7 is a diagram showing the structure of a sample in which Mo paste in the present invention is baked onto the surface of aluminum nitride.
A graph showing the relationship between the amount of , tensile strength and area resistance,
Figure 8 shows S10 at a constant amount of Mo! FIG. 9 is a graph showing the relationship between the MnO ratio and the tensile strength. FIG. 9 is a graph explaining an example of the amount of components of the Mo paste used in the present invention. FIGS. FIG. 12 is a manufacturing process diagram of an example of the semiconductor device of the present invention, and FIGS. 15 and 14 are graphs showing the results of a deterioration test of an example of the semiconductor device of the present invention and a conventional semiconductor device. , 1st
FIG. 5 is a cross-sectional structural diagram of an example of a conventional semiconductor device after a deterioration test. 10: Aluminum nitride substrate, 11: Mo, 12: 1
Jno ・Si0g glass or compound, 13:MnO@
Ago, 21: gl region, 26: Ni only region J, 27: el-AkOs, 51: region where Mo and MnO-5iO1 glass are mixed, 32:
Metal compound of Mo and N1, 35: Ni surface layer. 40
: Semiconductor chip, 41: Aluminum nitride chip, 42
: Solder, 43: Ponding bat, 44: Heat sink, 4
5: Hybrid integrated circuit board Figure 1111U5i02 Patent Appearance Hitachi, Ltd.

Claims (1)

[Claims] 1. In an aluminum nitride substrate in which at least a portion of the substrate surface is covered with a metal layer to which a semiconductor chip can be connected using a brazing material, at least a portion of the aluminum nitride substrate surface is covered with a metal layer to which a semiconductor chip can be connected.
1. An aluminum nitride substrate, the surface of which is covered with a brazable high-melting point metal layer, with or without a layer containing o, MnO and SiO_2 as components, and an intermediate layer. 2. The coating layer is the first layer of MnO-Al_2O_3 compound.
The aluminum nitride substrate according to claim 1, comprising a region, a second region in which Mo and MnO-SiO_2 glass or compound are mixed, and a Ni surface layer. 3. The coating layer according to claim 1, wherein the coating layer consists of a first region in which Mo and MnO-SiO_2 glass are mixed, a second region made of a metal compound of Mo and Ni, and a Ni surface layer. Aluminum nitride substrate. 4. In a method for manufacturing an aluminum nitride substrate in which at least a portion of the substrate surface is covered with a metal layer to which a semiconductor chip can be connected using a brazing material, at least a portion of the aluminum nitride substrate surface is coated with 80 to 95% by weight of the aluminum nitride substrate. Mo, 3.5-1
Applying a paste containing 1% MnO and 1.5-9% SiO_2, or a paste containing Mo and glass powder in the weight ratio in which the MnO and SiO_2 have been previously vitrified, 1200-1350 1. A method for producing an aluminum nitride substrate, comprising the steps of sintering at °C and forming a brazable refractory metal layer as a surface layer above the sintering step. 5. The process from application of the paste to sintering is the process of printing and applying the paste on the aluminum nitride substrate surface, and then 300~
A step of holding at 400°C for a maximum of 1 hour to decompose and scatter the organic components, raising the temperature to a maximum of 900°C in the above atmosphere, and
A process of improving the wettability between MnO and SiO_2 or its glass body, which is necessary to connect the o surface and the aluminum nitride substrate surface, and then a process of sintering at 1200 to 1350°C in a dry forming gas of hydrogen and nitrogen. The method for manufacturing an aluminum nitride substrate according to claim 4, which includes the steps of: 6. In an insulated semiconductor device having a structure in which a semiconductor chip, an aluminum nitride substrate, and a metal heat sink are tangential to each other via a brazing material, at least a portion of both main surfaces of the aluminum nitride substrate are made of Mo, MnO, and SiO_2. 1. An insulated semiconductor device, the surface of which is covered with a brazable high-melting point metal layer, with or without an intervening layer and an intermediate layer.