JPH06112339A - Ceramic package - Google Patents

Abstract

PURPOSE:To furnish a ceramic package of high density, high-speed correspondence, high radiation, simple form and high reliability which is fit LSI of high integration, high speed and large power consumption, and others. CONSTITUTION:A semiconductor element 12 is mounted on an AlN base 11 and connected electrically to a surface thin-film conductor 13 formed on the surface of the AlN base 11. A lid 15 made of ceramic of high heat-conductivity and sealing the semiconductor element 12 airtightly is joined to the AlN base 11. The surface thin-film conductor 12 is constituted of a metal material of which the main constituent is Al. A joining layer 16 for sealing the AlN base 11 and the lid 15 is constituted of glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic package provided with an AlN substrate, and in particular, has improved a thin film conductor for electrically connecting to a semiconductor element and a bonding layer between the AlN substrate and a sealing lid. Regarding ceramic packages.

[0002]

2. Description of the Related Art In recent years, as represented by BiCMOS and ECL, high integration of LSI, high speed, high power consumption,
With the progress of large-sized chips and the like, there is a tendency that a package mounting an LSI has higher density, higher speed, and higher heat dissipation. High density, high speed, and high heat dissipation of such packages are strongly demanded in the field of high-speed large-scale information processing such as workstations, minicomputers, and large computers.
In particular, it is an indispensable technology in the mounting technology of supercomputers. Recently, along with the personalization of computers and workstations, in addition to the above requirements, there is a strong demand for simplicity and high reliability.

In response to such requirements, the ceramic package is highly reliable when hermetically sealing an LSI, has excellent moisture resistance, and has a good heat dissipation property.
Used in PU, CMOS, ECL gate array, etc. High integration, high speed, large power consumption, large chip LS
For I, a package including a multilayer wiring substrate (AlN substrate) using an AlN ceramic material having high thermal conductivity has been developed. The coefficient of thermal expansion of AlN is similar to that of Si, and S
Another advantage is that the thermal stress when mounting an LSI mainly composed of i is small.

Up to now, the AlN substrate has often been manufactured by a thick film method in which a conductor such as W is screen-printed on an AlN ceramic green sheet, which is laminated and integrally fired to form a multilayer wiring substrate. However, recently, a problem has arisen that cannot be dealt with only by the thick film method.

One problem is the miniaturization of the conductor wiring pattern accompanying the increase in the number of pins and narrow pitch of LSI. That is, L
It has become possible to see that the connecting portion with the SI has a pitch of 100 μm or less, and it becomes difficult to form a pattern by the thick film method. Also, the connection method with the LSI is not limited to the wire bonding method as the LSI pitch becomes narrower.
The TAB method or flip chip connection is required, and bonding to a package with two or more cavities or connection to a thick film pattern has become difficult.

Another problem is the LSI ASI.
One example is how to deal with the package LSI with the change to C. That is, the gate array, standard cell, etc.
Since the development period of SIC / LSI has been shortened and the number of varieties has been increasing, short-term development and manufacture of packages are required. However, when the package is made only by the thick film method, the process from printing to firing is long,
The pattern cannot be changed easily. Further, as the pattern accuracy of the package becomes finer, it is necessary to more strictly control the shrinkage rate of the ceramic when firing the ceramic package, but it is difficult to control with a precision of 1% or less in the process.

Therefore, in order to solve these problems, AlN
A ceramic package in which a thin film conductor pattern is formed on the surface of a substrate has been developed and put into practical use. This is for example A
Underlayer such as Ti, Cr, Mo, W, C on 1N substrate
This is a thin film multilayer structure formed of an intermediate metal layer such as u, Ni and Pt and a surface conductor layer such as Au.

FIG. 4 shows a ceramic package having such a conventional structure, and FIG. 5 shows an enlarged structure of the joint portion of the sealing lid.

In the illustrated ceramic package, an LS which is a semiconductor element is mounted on an AlN substrate 1 having an inner layer wiring 1a.
The I2 is mounted and the LSI 2 is electrically connected to the thin film conductor 3 formed on the surface of the AlN substrate 1 by the bonding wire 4. In addition, on the surface of the AlN substrate 1,
A sealing lid 5 made of high thermal conductive ceramic that hermetically seals the LSI 2 is bonded via a bonding layer 6.

The thin film conductor 3 of the ceramic package is shown in FIG.
As shown in, the underlayer 3a such as Ti or Cr, Mo, W,
It has a thin film multi-layer structure including an intermediate metal layer 3b such as Cu, Ni and Pt and a surface conductor layer 3c such as Au. The bonding layer 6 between the AlN substrate 1 and the sealing lid 5 is composed of, for example, a metallization layer 7 having a similar thin film multilayer structure, a brazing material layer 8 such as AuSn solder, and the like.

In FIG. 4, 9 is an input / output pin connected to the inner layer wiring 1a of the AlN substrate 1, and 10 is a sealing lid 5.
Is a fin for heat radiation provided on the outer surface of.

[0012]

By the way, in the conventional ceramic package as described above, the thin-film conductor is subjected to a predetermined process through steps of multilayer film formation, resist coating, resist patterning, multilayer film etching and resist removal. Although a pattern is formed, it takes a long time for patterning because the step of forming a multilayer film is long and it is necessary to use an etching etchant corresponding to each film. Further, since a precious metal is used for the surface conductor layer, it becomes expensive, and for example, Au plating is required to form the surface conductor layer thickly, which further increases the number of steps.

In order to hermetically seal the ceramic package, metallization is required to join the sealing lid to the surface of the AlN substrate with a brazing material such as AuSn solder. This metallization is based on the thin film multilayer structure or W,
It is formed by a co-fired thick film of Mo and a thick-film paste printed film of Ag, Au, Cu, etc. However, in order to perform metallization of these, it is only necessary to carry out the respective metallizing steps such as printing baking, sputtering, and etching. However, a metallized region is required independently on the surface of the AlN substrate, which causes the formation region of the thin film conductor to be narrowed on the AlN substrate.

Further, in the conventional ceramic package,
Finally, as described above, the lead wire for plating for Au plating is formed in the multilayer wiring board. Therefore, when an attempt is made to pass a high frequency signal through the multilayer wiring board, this plated lead wire acts as an open stub, causing an anti-resonance state with a length of 1/4 wavelength and causing signal reflection. However, there is also a problem in that it cannot be transmitted.

The present invention has been made to solve such a problem and has a high density, a high speed, a high heat dissipation, a simple form, and a high reliability suitable for a highly integrated, high speed, large power consumption LSI or the like. It is intended to provide a ceramic package. That is, it is possible to easily and inexpensively form a thin film conductor by eliminating the need for plating and forming a lead wire for forming a thin film conductor, improve the high frequency characteristics, and improve the sealing lid joint part. It aims to realize a highly reliable and highly reliable ceramic package by omitting the metallization.

[0016]

To achieve the above object, the present invention is electrically connected to an AlN substrate and a semiconductor element formed on the surface of the AlN substrate and mounted on the AlN substrate. In a ceramic package comprising a thin film conductor and a ceramic sealing lid which is joined to the AlN substrate and hermetically seals the semiconductor element, the thin film conductor is made of a metal material containing Al as a main component, and The joining layer between the AlN substrate and the sealing lid is made of glass.

In the present invention, the surface of the AlN substrate is preferably polished to have a surface roughness Ra of about 20 nm to 0.5 μm. Further, in the metal material containing Al as a main component, which is a thin film conductor, Si, Cu or the like is added in order to suppress stress migration and electromigration.
You may add a trace amount about W%.

Furthermore, the sealing lid is, for example, AlN.
Made of high thermal conductive ceramics such as, for example, bonded to the AlN substrate after mounting the semiconductor element, and a low melting point glass or the like is applied to the glass of the bonding layer to bond at around 400 ° C. in an inert atmosphere such as He or N ₂ . It is desirable to carry out at temperature. It is desirable to form the glass on the bonding surface of the sealing lid in advance by a printing method or the like.

The semiconductor element is preferably mounted on the AlN substrate by die bonding using Ag glass, epoxy resin, polyimide resin, AuSn solder, PbSn high temperature solder, or the like. An LSI or the like is applied as the semiconductor element, and the LSI or the like and AlN
It is desirable to electrically connect to the thin film conductor on the substrate surface by wire bonding using a bonding wire of Al or Au.

[0020]

In the present invention, the ceramic package having such a structure is manufactured by the following method.

First, as an AlN substrate, an AlN co-firing circuit substrate (multilayer wiring substrate) having multi-layer inner layer wiring such as W or Mo is prepared. On the surface of the AlN substrate, a thin film wiring (Al thin film wiring) of a metal material containing Al as a main component is formed as a thin film conductor connected to the inner layer wiring. This Al
The thin film wiring can be formed, for example, by forming a film by sputtering, vapor deposition, ion plating or the like, and then patterning this Al thin film by etching or the like using a photolithography technique.

External leads such as input / output pins are metallized on predetermined exposed portions of W, Mo, etc. to form lands, which are then aligned and brazed to the lands.

Next, the semiconductor device LSI or the like is mounted on the AlN substrate manufactured by the above method by die bonding, and the LSI or the like is electrically connected to the thin film conductor by the wire bonding method or the TAB method. . Then, a ceramic sealing lid is bonded to the AlN substrate with glass to hermetically seal.

Through the above steps, the Al thin film wiring is formed, and the ceramic package including the glass-sealed AlN substrate is manufactured.

In such a ceramic package of the present invention, there is no need for plating when forming the thin film conductor on the surface of the AlN substrate, and it is possible to easily form a good thin film conductor pattern with low resistance and made by bonding. Further, at this time, since the plated lead wire is not required, high frequency signal transmission is possible and high frequency characteristics are excellent. Furthermore, since the AlN substrate and the ceramic sealing lid are directly bonded using glass without forming a metallized layer, even if the bonding layer and the thin film conductor come into contact with each other on the AlN substrate, there is no problem. There is no
The amount of heat radiated from the AlN substrate to the sealing lid can be increased by widening the formation area of the thin film conductor on the 1N substrate, and by expanding the area of the joint to the thin film conductor. Is increased to maximize the effective high thermal conductivity of AlN and improve heat dissipation. Moreover, since the oxide film is formed on the thin film surface of the Al thin film wiring at this bonding portion, the adhesiveness with glass is superior to the conventional Al wiring and the like, and the hermetic sealing is performed with high bonding strength. It can be done and reliability is improved.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a structure of a cavity-up type ceramic package, and FIG. 2 shows an enlarged structure of a lid sealing joint portion thereof.

In the ceramic package of the present embodiment, the LSI 12 which is a semiconductor element is mounted on the AlN substrate 11 having the inner layer wiring 11a, and the LSI 12 is electrically connected to the thin film conductor 13 formed on the surface of the AlN substrate 11 by the bonding wire 14. Connected to each other. Also, AlN
On the surface of the substrate 11, a sealing lid 15 made of high thermal conductive ceramic such as AlN for hermetically sealing the LSI 12 is bonded via a bonding layer 16. 19 is an AlN substrate 1
Input / output pins connected to the inner layer wiring 11a of No. 1 and heat radiation fins 20 provided on the outer surface of the lid 15.

In this embodiment, in this structure, the thin film conductor 13 is made of a metal material containing Al as a main component, and the bonding layer 16 between the AlN substrate 11 and the sealing lid 15 is formed.
Is made of glass. The bonding layer 16 is arranged on the AlN substrate 11 over the thin film conductor 13.

The ceramic package of this embodiment is manufactured by the following method.

First, W and Mo pastes are filled in the via holes 11b formed on the AlN green sheet, and a wiring pattern to be the inner layer wiring 11a is printed on the sheet.
When printing the wiring pattern, the pattern for the lead wire for plating is not provided. Then, the AlN green sheets are laminated by pressure and heating, and the organic substances are removed in the degreasing step, and then 1
The AlN substrate (AlN co-firing circuit substrate) 11 is manufactured by firing at about 800 to 1900 ° C.

The Al-based thin film conductor 13 is formed by a method such as sputtering, vapor deposition, or ion plating. In this case, the surface of the AlN substrate 11 is previously polished to have a surface roughness Ra of about 20 nm to 0.5 μm. This facilitates the thin film formation process, and the input / output pin 1
The reliability of the bonding strength of No. 9 is improved. Note that Al after firing
If the surface roughness of the N substrate is small, the thin film conductor 13
May be formed. In addition, before forming the thin film conductor 13, A
The 1N substrate 11 is ultrasonically cleaned with a neutral detergent, pure water, isopropyl alcohol, etc. to remove oil components, deposits and the like.

A small amount of Si, Cu or the like may be added to the Al thin film to be formed in order to suppress stress migration and electromigration of the Al thin film wiring.
A pattern is formed on the formed Al thin film by wet etching using aqua regia, hydrofluoric acid, or dry etching using chlorine or fluorine. A resist is used as the masking material. When the lift-off method is used, patterning is performed with a resist before forming a thin film, and then a thin film is formed to form a pattern. Al thin film is 0.2-5μ
m, preferably about 1 μm in thickness.

The joint portion of the input / output pins 19 of the AlN substrate 11 is metallized by a thick film method, a thin film method or the like. When the thick film method is used, the co-firing metal W,
Ni electroless plating is performed on the exposed portion of the back side of Mo, and heat treatment improves the adhesion. An input / output pin 19 made of Kovar or Cu alloy with a brazing material interposed
To join.

In the thin film method, the input / output pin 1 is formed on the Al thin film.
Since it is difficult to bond 9 to 9, it is necessary to form a metal thin film different from the Al thin film. For example, Ti / Ni / A
A metal thin film such as u or Ti / Cu is formed and patterned into a predetermined shape such as a circular shape or a rectangular shape to form a land. After that, the input / output pins 19 to which the brazing material has been temporarily fixed in advance are brazed to the obtained land using a jig in a vacuum or in an inert atmosphere.

The ceramic package of the present invention is
The joining process differs depending on the type of brazing material. Ag-
When using Cu or the like to join at a temperature higher than 800 ° C., the thin film conductor 13 is formed after joining the input / output pins 19 because the melting point of Al is exceeded. On the other hand, AuSn,
When Ag-Cu-In or the like is used for joining at a temperature equal to or lower than the melting point of Al, the input / output pin 19 may be joined after the pattern of the thin film conductor 13 is formed in advance.

On the AlN substrate 11 manufactured by the above method,
The LSI 12 is mounted. The LSI 12 is made of Ag glass, epoxy resin, polyimide resin, AuS on the AlN substrate 11.
Die bonding is performed using n solder, PbSn high temperature solder, or the like. Thin film conductor 1 on the surface of LSI 12 and AlN substrate 11
3 is electrically connected by a wire bonding method using a bonding wire such as Al or Au.

After the LSI 12 is mounted, the sealing lid 15 made of high thermal conductive ceramic such as AlN is bonded by using the low melting point glass as the bonding layer 16 and hermetically sealed. Sealed at 400 ° C in an inert atmosphere such as He or N _2.
Perform at around temperature. Glass is formed on the sealing lid 15 in advance by a printing method or the like.

More specifically, in this embodiment, the surface of the AlN substrate 11 manufactured by the above-mentioned method was polished with an abrasive to have an average surface roughness Ra = 0.4 μm. Then, as in the case of producing a normal ceramic package, Ni is metallized by electroless plating on the exposed surface of the back side of W and Mo that are co-firing metals,
An input / output pin 19 made of Kovar was joined thereon with an AuSn brazing material interposed.

AlN substrate 11 after connection of input / output pins 19
The surface of the thin film conductor 13 was washed with a neutral detergent, pure water, and isopropyl alcohol, and then a thin film conductor 13 was formed on the entire surface of the AlN substrate 11 polished by a film forming method such as sputtering or vapor deposition. The film thickness was about 3 μm. Subsequently, the resist is patterned into a desired pattern using a thick film positive resist, and a thin film conductor (Al thin film wiring) is formed by etching.
13 was formed. Etching is phosphoric acid, nitric acid, hydrochloric acid,
It was performed at room temperature using a mixed acid of acetic acid. The thin film conductor 13 is connected to the inner layer wiring 11a of the AlN substrate 11 via the via hole 11b.

Then, LS is formed on the produced AlN substrate 11.
I12 was die-bonded using Ag polyimide resin. The LSI 12 and the thin film conductor 13 were electrically connected by a wire bonding method using an Al bonding wire. After mounting the LSI 12, the sealing lid 15 made of AlN was sealed with the bonding layer 16 of low melting point glass. The sealing was performed at 400 ° C. in an inert atmosphere of N ₂ . The glass was formed on the sealing lid 15 in advance by a printing method or the like, further dried and melted before use.

Through the above steps, an Al thin film wiring was formed and a glass-sealed AlN package was manufactured. In addition, in order to improve the heat dissipation of the package, the heat dissipation fin 20 made of Al was screwed and attached to the screw provided on the sealing lid 15.

According to the present embodiment, it is possible to omit the plating when forming the thin film conductor 13 without providing a plating lead wire in the AlN substrate 11. Therefore, the thin film conductor 13 having low resistance and good bonding property can be obtained by a simple process,
Moreover, a ceramic package having good high frequency characteristics could be obtained by omitting the lead wire. Furthermore, the AlN substrate 1
Since it is not necessary to form a metallized layer at the joint portion of the sealing lid 15 and the sealing lid 15, the number of steps can be significantly reduced, and the joint layer 16 can be extended to above the thin film conductor 13 to improve heat dissipation and reliability. It was

(Embodiment 2) FIG. 3 shows the configuration of this embodiment. In this embodiment, as shown in the figure, it is manufactured in the form of a flat package. The same components as those in the first embodiment are designated by the same reference numerals in FIG. 3, and the description thereof will be omitted.

In this embodiment, an Al thin film is formed on the surface of the AlN substrate 11 on which the inner layer wiring 11a is formed by a thin film method such as sputtering or vapor deposition, and the thin film conductor 13 is formed by the photolithography technique. The thin film conductor 13 is connected to the inner layer wiring 11a through the via hole 11b. The input / output leads 21 were electroless plated with nickel on the exposed portions of W and Mo at the outer edge of the surface of the AlN substrate 11, and then joined by an AuSn brazing material. Joining is N
It was conducted at 400 ° C. in 2 atmospheres.

Then, the LSI 12 was mounted on the AlN substrate 11, and after wire bonding, the ceramic sealing lid 15 was bonded via the bonding layer 16 made of low melting point glass.

Also in this embodiment, it is not necessary to provide a plating lead wire in the AlN substrate 11, and a package having good high frequency characteristics can be obtained. Further, the thin film conductor 13 having low resistance and good bonding property was obtained, and further, the heat dissipation and reliability were improved and the number of steps was reduced.

In each of the above embodiments, the cavity-up type and flat type packages have been described, but the present invention can be applied to other package structures such as a chip carrier as long as the package structure and the material are the same.

[0049]

As described above in detail, according to the present invention, a high density, high speed, high heat dissipation, simple heat dissipation, and high reliability AlN ceramic suitable for high integration, high speed, and large power consumption LSIs. In the package, the plating for forming the thin film conductor and the plating lead-out wire for forming the thin film conductor are not required, and the package having good high frequency characteristics can be obtained. Also, A
By omitting the metallization at the joint between the 1N substrate and the sealing lid, the number of steps can be greatly reduced, and the joint can be extended to the thin film conductor, resulting in a highly reliable ceramic package with high heat dissipation. Will be realized.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the overall configuration of a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a schematic cross-sectional view showing the overall configuration of a second embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a conventional example.

5 is an enlarged view of a main part of FIG.

[Explanation of symbols]

 11 AlN substrate 12 LSI 13 thin film conductor 15 sealing lid 16 bonding layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kyoaki Yasumoto, Inventor, Komukai Toshiba Town, No. 1, Komukai-shi, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute Co., Ltd. (72) Inventor, Norio Toshiba Town No. 1 Toshiba Corporation Research Institute

Claims (1)

[Claims] 1. An AlN substrate, a thin film conductor formed on the surface of the AlN substrate and electrically connected to a semiconductor element mounted on the AlN substrate, and an airtight seal for the semiconductor element joined to the AlN substrate. In a ceramic package including a ceramic sealing lid that stops, the thin film conductor is made of a metal material containing Al as a main component, and a bonding layer between the AlN substrate and the sealing lid is made of glass. Ceramic package characterized by being configured.