JPH03270260A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve sealing airtightness and cooling effect of a cooling plate by specifying constitution of a metallized layer which is formed on a cap and the cooling plate. CONSTITUTION:A nickel-plated layer which is 0.5mum or more in film thickness with a fine crystal particle and a gold-plated layer which is 0.2mum-1.0mum in thickness and is formed on the nickel-plated layer are formed by recrystallizing metallized layers 4 and 8 which are formed on a cap 39 and a cooling plate 43. This recrystallized nickel-plated layer with the fine crystal particle can be obtained by heat treatment of an Ni-plated layer which is obtained by plating within a mixed gas of a reducing gas such as H2 gas or CO gas and an inactive gas such as N2 gas or CO2 gas, thus enabling sealing airtightness and cooling effect of the cooling plate to be improved.

Description

[Detailed Description of the Invention] [Summary] Regarding a semiconductor device, Pb is added to the surface of the Au plating layer constituting the metallized layer of the cap and the surface of the Au@gold layer constituting the metallized layer of the heat sink.
- A semiconductor device that can improve the sealing airtightness and the heat dissipation effect of the heat sink by making the 5N brazing material wet and spread sufficiently without creating any voids, thereby improving the reliability of the chip. A chip is connected face down to a package, a seal pattern formed on the package and a metallized layer formed on the cap are bonded with a brazing material, and a metallized layer formed on the back side of the chip. and a semiconductor device in which a metallized layer formed on the cap and a metallized layer formed on a heat sink are bonded together with a brazing material whose main component is Pb-5n, A nickel plating layer having a thickness of 0.5 μm or more and having dense crystal grains formed by recrystallization of the metallized layer, and a nickel plated layer having a thickness of 0.2 μm or more and 1.0 μm or less formed on the nickel plating layer. It is configured to have a layer.

[Industrial Field of Application] The present invention relates to a semiconductor device, and in particular, the present invention relates to a semiconductor device in which P is applied to the surface of an Au plating layer constituting a metallized layer of a cap and the surface of an Au plating layer constituting a metallized layer of a heat dissipation plate.
The present invention relates to a semiconductor device that can sufficiently wet and spread a b-Sn brazing material.

In recent years, TAB (Tape Auto) has been added to packages.
Semiconductor devices are attracting attention in which LSI chips are connected face-down by O+atedBonding and the connected LSI chips are sealed with a Pb-Sn brazing material using a cap and a heat sink. Specifically, this semiconductor device has a Ni plating layer/A formed on the cap.
A metallized layer consisting of a u plating layer (2 to 3 μm thick) and a metallized layer formed on the heat sink consisting of a Ti layer/MO layer/Ni layer (sputtered)/Ni plating layer/Au plating layer (2 to 3 μm thick) Adhesion with the Pb-Sn brazing material was performed. However, when bonding the cap and the heat sink using the Pb-Sn brazing material, the Pb-Sn brazing material is applied to the surface of the Au plating layer that makes up the metallized layer of the cap and the surface of the Au plating layer that makes up the metallized layer of the heat sink. There was a problem in that it did not wet and spread sufficiently and it was difficult to obtain sufficient sealing and airtightness.

For this reason, it is necessary to sufficiently wet and spread the Pb-Sn brazing material on the surface of the Au plating layer constituting the metallized layer of the cap and the surface of the Au plating layer constituting the metallized layer of the heat sink to obtain sufficient sealing airtightness. There is a demand for semiconductor devices that can

[Conventional technology]

FIG. 7 is a diagram showing the configuration of a conventional semiconductor device. The illustrated semiconductor device is the one reported in "Nikkei Microdevice June 1989 issue, P51, FIG. 2".

In this figure, 31 is a pan cage made of ceramics such as AlN, 32 is an external lead, and 33 is a pan cage 3.
Ti layer/Mo layer/Ni layer/Cr formed on 1
Seal pattern consisting of layer/Cu layer/Ni layer (sputtered)/NiNi plating 1i u plating layer, etc., 34 is a conductor pattern made of the same constituent material as the seal pattern 33, 35 is an insulator cover made of polyimide resin, etc.
36 is an adhesive layer made of Pb-Sn brazing material, 37 is a TAB lead made of copper foil plated with Sn, and 38 is Au.
39 is a cap made of Kovar alloy, etc., and 40 is a Ni plating 1 formed on the surface of the cap 39.
A metallized layer consisting of an i/Au plating layer (2 to 3 μm thick), 41 is an LSI chip, 42 is an LSI chip 41
Ti layer/Au layer formed on the back side (sputtered)
43 is a heat sink made of ceramics such as AlN, 44 is a Ti layer/MO layer/Ni layer (sputtered)/N1 plating layer/Aul gold Ji (2~ 45 is a gap filled with an inert gas such as N2 gas.

In the conventional semiconductor device, L is attached to the package 31 by TAB.
SI chips 4] are connected face down so that the patterned surfaces of the LSI elements, etc. This was done by using a Pb-Sn brazing material that would become the adhesive layer 36.

Specifically, this sealing is performed by bonding the seal pattern 33 formed on the pan cage 31 and the metallized layer 4o formed on the cap 39 with a Pb-Sn brazing material that becomes the adhesive layer 36, and also forming a seal pattern 33 formed on the back surface of the LSI chip 41. The metallized layer 42 and the metallized layer 40 formed on the cap 39 and the metallized layer 44 formed on the heat sink 43 are bonded together using a Pb-Sn brazing material which becomes the adhesive layer 36.

Note that since the sealing is performed in an inert gas atmosphere such as N2 gas, the gap 45 around the sealed LSI chimp 41
is filled with inert gas. Further, as the metallized layer 44 of the heat sink 43, after sequentially forming a Ti layer, a Mo layer, and NiN on the heat sink 43 by spunter method, further plating is performed to form a Ni plating layer and an Au plating layer on the 1'Ji layer. (2
The metallized layer 40 of the cap 39 includes a Ni plating layer and an Au plating layer (2 to 3 μm thick) on the surface of the cap 39 by plating.
A structure formed in sequence was used.

[Problem to be solved by the invention]

In the conventional semiconductor device described above, the metallized layer 40 consisting of the Ni plating layer/Au plating layer formed on the cap 39 and the Ti layer/M formed on the heat sink 43.

Layer/Ni layer (sputtered)/Ni1i gold layer/A u
Pb-Sn is used for adhesion to the metallized layer 44 consisting of a plating layer.
This was done using raw materials. However, when bonding the cap 39 and the heat sink 43 using the Pb-Sn brazing material, Pb is applied to the surface of the Au plating layer constituting the metallized layer 40 of the cap 39 and the surface of the Au plating layer constituting the metallized Ji 44 of the heat sink 43. - The Sn brazing material does not sufficiently wet and spread, and as shown in FIG. 8, the metallized layer 4 of the cap 39
A gap 51 may be formed between the metallized layer 44 of the metallized layer 40 and the heat dissipation plate 43, or a void may be formed between the Au plating layer composing the metallized layer 40 and the adhesive layer 36 made of Pb-Sn brazing material, resulting in insufficient sealing. There was a problem in that it was difficult to obtain airtightness. Further, there was a problem in that the heat dissipation effect of the heat dissipation plate 43, which dissipates heat from the cap 39 via the adhesive layer 36 made of Pb-Sn brazing material, deteriorated. If the sealing airtightness is not sufficient, H! O10□ etc. enter the gap 45 and LS
There are problems such as corrosion of the I chip 41 and the like, and if the heat dissipation effect of the heat sink 43 deteriorates, the shank temperature of the LSI chip 4] increases during actual use, shortening its life.

The reason why the Pb-Sn brazing material does not sufficiently wet and spread on the gold-plated surface is considered to be due to the following reasons.

The Ni plating layer, which is simply formed from two plating layers constituting the metallization 140.44, is not a dense film and has unevenness and rough surface condition, and easily leaves residues such as oxides on the surface. The entire plating layer is formed with this remaining. Then, during heating, the residue on the Ni plating layer diffuses onto the surface of the Au plating layer and comes out. Therefore, Pb-
It is thought that this makes it difficult for the Sn brazing material to sufficiently wet and spread.

Therefore, the present invention provides the surface of the Au plating layer constituting the metallized layer of the cap and the surface of the Au plating layer constituting the metallized layer of the heat sink.
By making the Pb-Sn brazing material sufficiently wet and spread on the surface of the plating layer with almost no voids, it is possible to improve the sealing airtightness and the heat dissipation effect of the heat dissipation plate.
It is an object of the present invention to provide a semiconductor device that can improve the reliability of an I-chip.

[Means to solve the problem]

In order to achieve the above object, in the semiconductor device according to the present invention, the chip is connected to the package face down, the seal pattern formed on the pan cage and the metallized layer formed on the cap are bonded with a brazing material, and the back surface of the chip is bonded to the metallized layer formed on the cap. In a semiconductor device in which a formed metallized layer, a metallized layer formed on the cap, and a metallized layer formed on a heat sink are bonded by a brazing material whose main component is Pb-Sn, the cap and the heat sink are bonded together. A nickel plating layer having a thickness of 0.5 μm or more and having dense crystal grains by recrystallizing the metallized layer formed on the nickel plating layer and a nickel plating layer having a thickness of 0.2 μm or more and 1.0 μm formed on the nickel plating layer.
The total plating layer is less than m.

As a formation method for obtaining a recrystallized nickel plating layer having dense crystal grains according to the present invention, a Ni plating layer obtained by plating is formed using H! Examples include a method of heat treatment in a mixed gas of a reducing gas such as gas or CO gas and an inert gas such as N2 gas or CO or gas. in this case,
It is preferable that the Ni plating layer is not oxidized, and a reducing gas may be used as described above.

In the present invention, the lower limit of the thickness of the nickel plating layer is O-5.
When the thickness is less than 0.5 μm, Ni is recrystallized during heat treatment to obtain a nickel plating layer with dense crystal grains. ), which is practically undesirable.

In the present invention, the lower limit of the film thickness of the entire plating layer is set to 0.2 μm because if it is thinner than 0.2 μm, oxygen, moisture, etc. in the air will enter through the gaps in the Au plating layer when stored for a long time. This is because the metal film is oxidized and deteriorated in quality, and the underlying Ni etc. is diffused into the entire plating layer, which reacts with oxygen, moisture, etc. in the air and oxidized and deteriorated, which is not desirable for practical purposes. be. In addition, the upper limit of the thickness of the entire plating layer was set to 1.0 μm because if it becomes thicker than 1.0 μm, the amount of melted Au increases when the Pb-Sn brazing material is heated and melted, and the Pb-Sn brazing material increases.
This is because the melting point of the brazing material increases, making it difficult to wet and spread, which is not preferred in practice. Furthermore, as shown in Fig. 6, the coating of the present invention in which the thickness of the entire plated layer is 0.2 μm or more and 0.1 μm or less is superior to those with other thicknesses in terms of run-off occurrence rate and pull-in occurrence rate. Both showed good values, and it was found that the solder flowability was good.

In the present invention, the preferred weight/M weight ratio of the Pb-Sn brazing material is 83% by weight or more for Pb and 17% by weight or less for Sn. In this case, since the solidus line and the liquidus line are close to each other, coagulation can be completed quickly, which is preferable.

The brazing material whose main component is Pb-Sn according to the present invention includes brazing material consisting only of Pb-Sn, Ag-containing Pb-
An example is brazing material made of Sn.

[Effect]

In the present invention, as shown in FIG. 1, FIG. 3, and FIG. Since the groove bottom is recrystallized to have dense crystal grains of 2 μm (0.5 μm or more), the surface has almost no irregularities and has a more uniform surface condition than the conventional Ni plating layer formed by simply plating. ing. Then, with almost no residue such as oxides left on the surface, the film thickness is reduced to 0.5 mm.
Au plating alloy layer 8 of μm (0.2 or more and 1.0 or less pm)
b4e is formed, the Au plating layer 8 is formed during heating.
AU plating alloy 881 because the residue on Ni plating alloy layer 8a4d is hardly diffused and exposed on the surface b, 4d.
40 surface Pb-5nO- material can be sufficiently wetted and spread with almost no voids.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

1 to 5 are diagrams for explaining one embodiment of a semiconductor device according to the present invention, and FIG. 1 shows an I of the semiconductor device of one embodiment.
FIG. 2 is a diagram illustrating a method of manufacturing a Pb-Sn brazing material according to an embodiment, FIG. 3 is a diagram illustrating a method of manufacturing a metallized layer of a heat dissipation plate according to an embodiment, and FIG. 5 is a diagram illustrating a method of manufacturing a cap 7 and a metallized layer of the cap according to one embodiment, and FIG. 5 is a diagram illustrating a method of manufacturing a semiconductor device according to one embodiment.

In these figures, the same reference numerals as in FIG. 7 indicate the same or equivalent parts, 1 is a Pb ingot, 2 is a Sn ingot, and 3 is, for example, Pb:5n=90% by weight: 10% by weight of Pb-Sn11:+- 4 is a metallized layer consisting of a Ti layer 4a/MO layer 4b/Ni layer 4c/Ni plating Ji4d/Au plating layer 4e formed on the heat dissipation plate 43; 5 is a Kovar alloy (42A11oy may also be used);
6 is a drawing die, 7 is a cutting die, 8 is a metallized layer consisting of Ni plating all gold layer 8a/Au plating layer 8b formed on the cap 39, and 9 is a TAB lead 37 with loose ends. This is a film carrier made of polyimide tape, etc., formed on the TAB lead 37 to ensure that the TAB lead 37 does not move.

First, a method for manufacturing the Pb-sn brazing material 3 that will become the adhesive layer 36 will be described using FIG.

First, a high-purity Pb ingot 1 and a high-purity Sn ingot 2 are melted at, for example, Pb:5n=90% by weight:10% by weight, and then cooled and crystallized to obtain Pb-Sn.
Forming a mass of brazing material 3 6 Next, the mass of Pb-Sn brazing material 3 is squeezed out into a rod shape, rolled into a sheet shape with a desired thickness, and then molded or cut into a desired shape. A Pb-Sn brazing material 3 can be obtained.

Next, a method for manufacturing the metallized layer 4 of the heat sink 43 will be described using FIG. 3.

Here, AlN ceramics are used for the heat dissipation plate 43, which has a high thermal conductivity of about 150 w/m·K, has an excellent heat dissipation effect, and has a thermal expansion coefficient of about 4.
This is because the LSI chip 41 is less burdened by thermal stress because its ppm/K is very close to Si's approximately 3 ppga/K.

First, a film with a thickness of, for example, 0 is formed on the heat sink 43 by sputtering.
A Ti layer 4 a of 11 μm, an MO layer with a thickness of 2 μm, for example.
After sequentially forming the layer 4b and the Ni layer 4C having a film thickness of, for example, 1 μm, the Ti of the Ti layer 4a is replaced with a heat sink 43 made of AIN.
In order to improve the adhesion between the Ti layer 4a and the heat sink 43 by diffusing the Ti layer 4a, heat treatment is performed in a mixed gas of H, gas and N2 gas at 930° C., for example.

The reason why the Ti layer 4a is formed here is to obtain adhesion between the heat sink 43 made of IN and the MO layer 4b.
The layer 4b is formed with a thermal expansion coefficient of approximately 4 ppm1
/k to bring the thermal expansion coefficient of the metallized layer 4 as a whole close to that of the heat sink 43, and the Nj layer 4C
is formed in order to obtain adhesion to the Nj plating alloy layer 4d. Next, after forming a Ni plating alloy layer 4d having a film thickness of, for example, 2 μm on the Ni layer 4C by plating, the Ni plating alloy layer 4d is recrystallized at 720° C. Hz to have dense crystal grains. Heat treatment is performed in a mixed gas of gas and N2 gas. Next, Ni1i gold layer 4d is formed by plating.
By forming an Au plating alloy layer 4e having a thickness of, for example, 0.5 μm on the upper C layer, a Ti layer 4a/Mo ii 4 is formed.
b/Ni layer 4C (sputtered)/Ni plating layer 4d/
A metallized layer 4 made of an Au plating layer 4e can be obtained.

Next, a method for manufacturing the cap 39 and the metallized layer 8 of the cap 39 will be described using FIG.

First, a plate-shaped hoop material 5 such as Kovar alloy (42A11oy etc. may be used) is formed into a desired shape using a drawing die 6.
The cap 39 is formed by cutting into desired dimensions using the cutting die 7. Next, after degreasing and cleaning the cap 39, the surface of the cap 39 is plated to a thickness M of, for example, 2 μm.
After forming the Ni-plated alloy layer 8a, heat treatment is performed in an H2 gas atmosphere at, for example, 720° C. in order to recrystallize the Ni-plated alloy layer 8a and make it have dense crystal grains. The heat treatment temperature here is preferably 550°C or more and 800°C or less. Next, by plating to form an Au plating alloy layer 8b having a thickness of, for example, 0.5 μm on the Ni plating layer sa, it is possible to obtain a metallized layer 8 consisting of the Ni plating all gold layer 8a/the Au plating 1i8b. can.

Next, a method for manufacturing a semiconductor device will be described using the Pb-Sn brazing material 3 formed as described above, the heat sink 43 on which the metallized layer 4 is formed, and the cap 39 on which the metallized layer 8 is formed.

First, as shown in FIGS. 5(a) and 5(b), the T A B +7− board 37 is reinforced with a pan 138 made of Au or the like formed on the LSI chip 41 and a film carrier 9.
and are bonded together by heating and pressure. In addition, LSI Chimp 4
A metallized layer 42 consisting of a Ti layer/Nil/Ag layer (all of which are sputtered) is formed on the 1 rear surface.

Next, as shown in FIG. 5(c), the TAB lead 37 is cut to a predetermined length. At this time, the reinforced film carrier 9, which prevents the TAB leads 37 from sticking, is removed.

Next, as shown in FIGS. 5(d) and 5(e), the LSI chip 41 is placed so that the patterned surface of the LSI element etc. is in the pan cage 3.
It is connected to the package 31 face down so as to face the first side by heating and pressurizing. At this time, the TAB lead 37 of the LSI chip 41 and the conductor pattern 34 of the pan cage 31
is connected. In addition, in the pan cage 31 here, T
The seal pattern 33 is composed of an i layer/Mo layer/Ni layer/Cr layer/Cu layer/Ni layer (sputtered)/Ni layer/Au layer (plated), etc., and the material is the same as that of the seal pattern 33, for example. Conductor pattern 3 made of constituent materials
4, an insulator cover 35 made of polyimide resin, etc.
For example, the external lead 32 is formed of a pin made of Kovar alloy and plated with Au.

Next, as shown in FIG. 5(f), a frame-shaped Pb-Sn brazing material 3, a frame-shaped cap 39, a pellet-shaped Pb-Sn
The brazing material 3 and the heat dissipation vi 43 are placed one after another. Note that a metallized layer 8 consisting of a Ni plating layer 8a/Aug gold layer 8b is formed on the surface of the cap 39, and a T i Jig 4 a / M c Ji4 b /
Ni layer 4 (sputtered) c/Ni plating layer 4 d/
A metallized layer 4 provided with an Au plating layer 4e is formed.

And N! Heating in a gas atmosphere (e.g. 300°C),
A seal pattern 33 and cap 39 formed on the package 31 by applying pressure (for example, 100 g/an)
The metallized layer 8 formed on the Pb
-A metallized layer 42 and cap 3 formed on the back surface of the LSI chip 41 while being bonded with the Sn brazing material 3.
A semiconductor device as shown in FIG. 1 is completed by bonding the metallized layer 8 formed on the surface of the metallized layer 8 and the metallized layer 4 formed on the lower surface of the heat sink 43 using the Pb--Sn brazing material 3.

That is, in the above embodiment, first, the Ni plating alloy layer 8a4d constituting the metallized layer 8.4 formed on the cap 39 and the heat radiation t5.43 has a film thickness of, for example, 2 μm (
0.5 μm or more) to have dense crystal grains. Therefore, the surface has almost no unevenness and the surface condition is more uniform than in the case of a conventional Ni plating layer formed only by plating. Next, the film thickness is reduced to 0.5 μm, for example, with almost no residues such as oxides left on the surface.
m<0.2 μm or more and 1.0 pm or less), an all-Au plating all-gold layer 8b4e can be formed. Therefore, during heating, the residues on the Ni plating layers 8a and 4d are hardly diffused and exposed on the surfaces of the Au plating layers 8b and 4e. It can be made to sufficiently wet and spread without causing almost any growth. Therefore, the sealing airtightness and the heat radiation effect of the heat sink 43 can be improved, and the reliability of the LSI chip can be improved.

In this embodiment, a case has been described in which the Ti layer 4a, the MO layer 4b, and the NiN4c formed by sputtering are used as the base layer constituting the metallized layer 4 formed on the heat dissipation plate 43. The present invention is not limited to this, and for example, a layer obtained by coating and baking a metal paste such as W or MO may be used as the base layer.

〔Effect of the invention〕

According to the present invention, A constituting the metallized layer of the cap
Au constituting the surface of the plating layer and the metallized layer of the heat sink
To improve the reliability of LSI chips by making it possible to sufficiently wet and spread the Pb-Sn brazing material on the surface of the plating layer so as to hardly create voids, thereby improving the sealing airtightness and the heat radiation effect of the heat sink. It has the effect of being able to.

[Brief explanation of drawings]

1 to 5 are diagrams for explaining one embodiment of a semiconductor device according to the present invention, FIG. 1 is a diagram showing the configuration of a semiconductor device of one embodiment, and FIG. - A diagram illustrating a method for manufacturing the Sn brazing material, FIG. 3 is a diagram illustrating a method for manufacturing a metallized layer of a heat sink according to an embodiment, and FIG. 4 is a diagram illustrating a method for manufacturing a cap and a metallized layer of a cap according to an embodiment. 5 is a diagram illustrating a method for manufacturing a semiconductor device according to an embodiment. FIG. 6 is a diagram illustrating details of the present invention. FIG. 7 is a diagram illustrating the configuration of a conventional semiconductor device. , FIG. 8 is a diagram explaining the problems of the conventional example. 3... Pb-Sn brazing material, 4... Metallized layer, 4d... Ni plating layer, 4e... Au plating layer, 8... ...Metallized layer, 8a...Ni plating layer, 8b...Au plating layer, 31...Package, 33...Seal pattern, 39... ... Cap, 41 ... LSI chip, 42 ... Metallized layer, 43 ... Heat sink. (High-purity Pb) (High-purity Sn) While explaining the manufacturing method of the Pb 5n brazing material of one embodiment, Figure 2 is a national policy diagram showing the structure of the semiconductor device of one embodiment (Press processing) (Cleaning, degreasing treatment) 〉 ↓ ↓ Heat treatment (720°C, in H2 gas) 2< Figure illustrating the manufacturing method of a semiconductor device according to one embodiment Figure 2 depicting the configuration of a conventional semiconductor device Figure 2 Detailed explanation of the present invention Figure 2 Diagrams to explain example tasks

Claims (2)

[Claims] (1) The chip (41) is packaged face down (
The seal pattern (33) formed on the package (31) and the metallized layer (8) formed on the cap (39) are bonded by brazing material (3, 36), and the chip (31) is connected to the chip (31). 41) The metallized layer (42) formed on the back surface, the metallized layer (8) formed on the cap (39), and the metallized layer (4) formed on the heat sink (43) are composed mainly of Pb-Sn. Raw material (3,
36), the metallized layers (4, 8) formed on the cap (39) and the heat sink (43) are recrystallized to have a film thickness with dense crystal grains. Nickel plating layer (4d,
8a) and the gold plating layer (4) with a film thickness of 0.2 μm or more and 1.0 μm or less formed on the nickel plating layer (4d, 8a).
e, 8b). (2) The semiconductor device according to claim 1, wherein the weight component ratio of the Pb-Sn brazing material (3, 36) is 83% by weight or more of Pb and 17% by weight or less of Sn.