JPH0789574B2 - Pellet mounting board manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wiring forming technique, and particularly to a technique effectively applied to a pellet mounting substrate of a semiconductor device.

[Background technology]

As a semiconductor device, there is a so-called pin grid array type semiconductor device of glass sealing type, for example, whose pellet mounting substrate is formed of a multilayer ceramic substrate.

On the pellet mounting substrate, a metallization layer for pellet mounting is adhered and formed, and a wiring also made of the metallization layer is extendedly formed around the metallization layer.

By the way, since a ceramic substrate is usually manufactured by sintering a powder raw material, irregularities due to the raw material and the manufacturing method are present on the surface thereof. Therefore, when the metallized wiring layer is formed by vapor deposition or the like, the thickness of the metallized layer becomes uneven, and if the wiring layer is miniaturized, its electric resistance becomes very large. Further, the present inventor has found that there is a problem that a wiring that does not have continuity is formed.

The glass-sealed pin grid array type semiconductor device is described in "VLSI Device Handbook", P228-229, published on November 28, 1983, by Science Forum.

[Object of the Invention]

An object of the present invention is to provide a technique effective when applied to the miniaturization of the wiring to be formed on the pellet mounting substrate having the through hole wiring made of ceramic.

Another object of the present invention is to provide a technique effective when applied to the multi-layering of the miniaturized wiring.

[Outline of Invention]

The above and other objects and novel features of the present invention will be apparent from the description of the present specification and the accompanying drawings.

That is, a wiring layer formed by metallization is formed by forming one or more glass layers for forming a metallized layer on the upper surface of a pellet mounting substrate made of ceramic in which a through-hole wiring layer having an end portion on the upper surface is formed. Since the wiring layer can be formed on a smooth surface, the wiring layer can be stably formed to have a uniform thickness, thereby achieving the above object.

[Embodiment 1] FIG. 1 is a partially enlarged cross-sectional view of a semiconductor device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of a semiconductor device of the present embodiment 1 taken along a plane substantially cutting the center thereof. It is shown.

The semiconductor device according to the first embodiment is a so-called pin grid array type semiconductor device, and a semiconductor pellet 3 is bonded to the upper surface of a pellet mounting substrate 2 made of ceramic with a back surface to which external terminals 1 are mounted. This pellet 3
It is electrically connected to a wiring layer (which is electrically connected to the external terminal 1) on the upper surface of the substrate 2 via a wire 4 made of gold or aluminum. Further, the pellet 3 is, as shown in FIG. 2, a ceramic cap 6 having a U-shaped cross section, which is welded around the substrate 2 with a low melting point glass 5.
It is sealed with.

The pellet mounting substrate 2 is not particularly limited, but is manufactured by a known method in which two ceramic green sheets on which a metallized layer has been printed and formed in advance are pressure-laminated and are sintered. The substrate 2 in the sintered state is integrated regardless of the two green sheets in advance.

In FIG. 1, corresponding to the green sheet in advance,
For the sake of convenience, the pellet mounting substrate 2 is shown as being composed of a two-layer ceramic substrate with the dashed line shown as the boundary. A metallization layer 7 made of, for example, tungsten is formed on the upper surface of the first layer substrate 2a, and the metallization layer 7 is connected to the upper end of a through hole wiring body 8 penetratingly formed in the first layer substrate 2a. In addition, it is connected to the lower end of a through-hole wiring body 8a formed through the second layer substrate 2b. Both through-hole wiring body
8, 8a are formed of the same material as the metallized layer 7.

The lower end of the through-hole wiring body 8 of the first layer substrate 2a is connected to the external terminal 1 by silver solder or the like. Second layer substrate
The upper end of the through-hole wiring 8a of 2b is exposed on the upper surface of the substrate 2b, and a conductor layer 9 having poor wettability with glass such as a nickel layer formed by plating or the like is formed thereon. There is.

A glass layer 10 is deposited on the upper surface of the second layer substrate 2b except on the conductor layer 9, and metallized layers 11 and 12 made of evaporated aluminum are deposited on the upper surface of the glass layer 10. The semiconductor pellet 3 is bonded onto the metallized layer 11 via a gold-silicon eutectic alloy layer. The pellet 3 is connected to a metallized wiring layer 12 made of aluminum formed on the upper surface of the glass layer 10 around the pellet 3 via a bonding wire 4. The wiring layer 12 is electrically connected to the through hole wiring body 8a.

In the semiconductor device of Example 1, since the glass layer 10 is adhered to the ceramic substrate and the wiring 12 is formed on the upper surface of the glass layer 10, the surface is extremely smooth, so that the metallized layer having a uniform thickness is formed. Can be deposited by vapor deposition or the like. Therefore, even if the wiring layer 12 is miniaturized, it is possible to prevent the increase in resistance, the disconnection of wiring, and the like due to the uneven thickness of the metallized layer.

Therefore, by forming the wiring layer 12 with a constant width, it is possible to stably provide fine wiring having substantially the same electrical characteristics.

The pellet mounting substrate 2 can be formed as follows. First, after forming a ceramic multilayer substrate by the usual method as described above, nickel is plated to form the upper end surface (conductor layer) 9 of the through-hole wiring 8a.
Next, the glass layer 10 is formed by depositing the glass paste on the entire surface and heating and melting it at a predetermined temperature.
At this time, since the upper end surface 9 of the through hole portion 8a is made of nickel that does not wet the glass, the glass is repelled and the upper end surface 9 is not adhered to the glass.
Therefore, in Example 1, the step of exposing the upper end surface 9 after forming the glass layer 10 is not necessary, and the wiring layer 12 can be immediately applied.

When a conductor layer such as nickel is not deposited in advance, the glass is easily wet because tungsten is oxidized during firing, and as a result, only heat treatment for forming the glass layer 10 is performed as described above. It is necessary to note that it is difficult to surely expose the through-hole electrode 8a.

The pellet 3 is joined to the pellet mounting portion 11 made of an aluminum layer metallized simultaneously with the wiring layer 12 through the gold-silicon eutectic as described above.

[Embodiment 2] FIG. 3 is a partially enlarged sectional view of a semiconductor device according to Embodiment 2 of the present invention. The semiconductor device of Embodiment 2 is substantially the same as that of Embodiment 1 described above.

In the second embodiment, the glass layer 10 for forming metallization such as wiring is formed on the upper surface of the pellet mounting substrate 2 in a two-layer structure of a first layer 10a and a second layer 10b.

That is, the wiring layer 12a on the upper surface of the first layer 10a is made of copper, but the structure is the same as that of the glass layer 10 and the aluminum wiring on the upper surface of the first embodiment. The second layer 10b is
The entire surface including the wiring layer 12a is adhered and formed.
The pellet 3 is bonded to the upper surface of the second layer 10b in the same manner as in the first embodiment, and the pellet 3 is electrically connected to the aluminum wiring layer 12b around the pellet 3 by the wire 4.
The wiring layer 12b is electrically connected to the wiring layer 12a through the perforated portion 13 of the second layer 10b.

The glass layer 10 having the two-layer structure can be formed as follows.

Unlike the case of the first embodiment, the first layer 10a is formed by applying a crystallized glass paste and melting it.
Next, a wiring layer is formed by depositing copper by vapor deposition or the like.
12a is formed, and the surface of the wiring layer 12a is chemically or physically treated, for example, oxidized to impart wettability to glass.

Next, the whole of the first layer 10a and the wiring 12a is coated with a glass paste as in the above-mentioned embodiment, and the same is melted by heating in the same manner as the first layer 10a to form the second layer 10b.

After that, the perforated portion 13 is formed in a predetermined portion by etching such as dry etching, and aluminum is deposited on the upper surface of the second layer 10b by vapor deposition or the like to form the wiring layer 12b and the pellet attachment portion. It can be formed in the same manner as in the first embodiment.

〔effect〕

(1). To form a metallized wiring layer on a smooth surface by forming a glass layer for metallization formation on the upper surface of a pellet mounting substrate made of ceramic in which a through-hole wiring layer having an end on the upper surface is formed. Therefore, the wiring layer can be formed with a substantially constant thickness.

(2). From the above (1), even if the wiring layer is miniaturized, it is possible to prevent a high resistance portion and a cut portion from being partially generated, so that it is possible to form a pellet mounting substrate on which highly integrated pellets can be mounted.

(3). By using two or more glass layers, it is possible to further improve the degree of integration of the pellets to be mounted.

(4). By forming the upper end surface of the through-hole wiring part by coating a conductive material with poor wettability to glass by plating etc., it is possible to completely prevent the upper end surface of the through-hole wiring part from getting wet by the glass when melting the glass. Therefore, the wiring layer can be metallized without the step of exposing the upper end surface after the glass layer forming step.

(5). According to the above (4), it is possible to inexpensively manufacture a semiconductor device including a pellet mounting substrate on which highly reliable fine wiring is formed.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention.

For example, in the above-mentioned embodiment, the glass layers having one and two glass layers are shown, but the number of glass layers is not limited to this and may be three or more.

The through-hole wiring layer may be made of any metal other than tungsten, such as molybdenum, as long as it can be used for the same purpose. Needless to say, metal such as gold may be deposited on the upper end surface of the through-hole wiring layer instead of nickel, and the upper end surface may be left over during the formation of the through-hole wiring layer, that is, during the glass baking process. Other metals do not necessarily have to be deposited if they have not been oxidized.

Further, it goes without saying that the material of the wiring layer formed by metallization on the upper surface of the glass layer is not limited to that of the above embodiment. For example, in Example 2, the wiring on the upper surface of the second layer is not limited to aluminum, but may be formed of the same material as that of the first layer, that is, copper.

[Field of application]

In the above description, the case where the invention made by the present inventor is mainly applied to the so-called pin grid array type semiconductor device which is the field of application which is the background has been described, but the present invention is not limited thereto and, for example, a through hole. A semiconductor device in which a pellet mounting substrate is formed of a ceramic substrate on which wiring is formed is an effective technique when applied to semiconductor devices of various types such as a chip carrier type.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a part of a semiconductor device according to a first embodiment of the present invention, FIG. 2 is a schematic sectional view showing a semiconductor device of the first embodiment, and FIG. FIG. 7 is an enlarged cross-sectional view showing a part of the semiconductor device which is Embodiment 2. 1 ... External terminal, 2 ... Substrate, 2a ... First layer substrate, 2b ...
… Second layer substrate, 3 …… Pellet, 4 …… Wire, 5 ……
Low melting point glass, 6 ... Cap, 7 ... Metallized, 8,
8a ... through-hole wiring, 9 ... upper end surface, 10 ... glass layer, 10a ... first layer, 10b ... second layer, 11 ... aluminum-gold-silicon eutectic, 12, 12a, 12b ... … Wiring, 13… Perforated part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Okinaga 1479 Kamimizuhonmachi, Kodaira-shi, Tokyo Inside Hitachi Ultra ESI Engineering Co., Ltd. (72) Inventor, Shoji Matsuue, Kodaira-shi, Tokyo Honmachi 1479, Hitachi Ultra ELS Engineering Co., Ltd. (72) Inventor Hiroshi Tate 1479, Josui Honcho, Kodaira-shi, Tokyo Hitachi Ultra ELS Engineering Co., Ltd. (72) Inventor Michiaki Furukawa 1450, Kamimizuhonmachi, Kodaira-shi, Tokyo Inside the Hitachi, Ltd. Device Development Center (72) Inventor Kanji Otsuka 1450, Kamimizuhoncho, Kodaira-shi, Tokyo Inside the Hitachi, Ltd. Device Development Center (72) Masami Terazawa Kyoto Prefecture From 22 Kyocera Co., Ltd. (72) at 5 Inoue-cho, Higashino-Kita, Yamashina-ku, Kyoto Who Yuji Fujinaka Kyoto-shi, Kyoto Yamashina-ku, Higashinokitainoue-cho Address 5 22 Kyocera within Co., Ltd. (56) Reference Patent Sho 48-32475 (JP, A) JP Akira 53-36666 (JP, A)

Claims (6)

[Claims] 1. A ceramic pellet comprising a through-hole wiring layer extending in the direction of the upper and lower surfaces and a metallization layer extending in the surface direction of the upper surface and connected to the through-hole wiring layer. A method of manufacturing a mounting substrate, the step of preparing a ceramic substrate on which the through-hole wiring layer reaching the upper surface thereof is prepared, and coating the exposed portion of the through-hole wiring layer with a metal having poor glass wettability, After the step, a step of depositing a glass paste on the upper surface of the substrate including a metal having poor glass wettability, and heating and melting the deposited glass paste,
Forming a glass layer covering the upper surface of the substrate and exposing the metal having poor glass wettability, and forming the metallized layer connected to the metal having poor glass wettability and extended on the glass layer A method of manufacturing a pellet mounting substrate, comprising: 2. The method of manufacturing a pellet mounting substrate according to claim 1, wherein the through-hole wiring layer is made of tungsten, and the metal having poor glass wettability is made of nickel. 3. The method for manufacturing a pellet mounting substrate according to claim 1, wherein the metallized layer is made of vapor-deposited aluminum. 4. The ceramic substrate is a multi-layer substrate having a metallization layer formed between the upper surface and the lower surface of the substrate, and the ceramic substrate is a multi-layer substrate. A method for manufacturing a pellet mounting substrate according to item. 5. The method for manufacturing a pellet mounting substrate according to claim 4, wherein the through-hole wiring layer and the intermediate metallization layer are made of the same metal. 6. A ceramic pellet mounting substrate having an external terminal attached to the lower surface thereof connected to the through-hole wiring layer.
Item 6. A method for manufacturing a pellet mounting substrate according to any one of items 5 to 5.