JPH1154647A - Composite package for semiconductor element and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure good electrical connection at a connection pad by coating the surface of the connection pad for making bump connection between a resin board and a ceramic substrate with a thin gold film. SOLUTION: The composite package for a semiconductor comprises a ceramic substrate 11 and a resin board 10 pasted through an adhesive 13. The resin board 10 incorporates silver bumps 22 and is sandwiched between copper foils patterned to form a surface wiring 35 of I/O pads and second connection pad parts, i.e., lands 31. The second connection pad part 31 of the resin board 10 is coated with a gold plated layer 51 on an underlying Ni plating layer 41 and the connection pad part 39 of the resin board 10 is coated with a gold plated layer 55 through an Ni plated layer 45. According to the structure, good electrical connection can be ensured at the connection pad part 39.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-terminal, narrow-pitch semiconductor device package, and more particularly to a semiconductor device composite package in which a ceramic substrate and a resin substrate are bonded and joined together, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Various types of packages, such as ceramics, resins, and metals, on which semiconductor chips such as LSIs are mounted, have been increased in density due to high integration, high speed, large power consumption, and large chips of LSIs. High-speed response and high heat dissipation are required. In addition, the applications of these semiconductor chips are wide ranging from industrial applications such as workstations, personal computers, and computers to electronic devices such as portable devices, printers, copiers, cameras, televisions, and videos. The performance itself has also improved.

A package on which an LSI chip of high performance and high integration density is mounted must be able to be connected to the LSI chip with multiple terminals and a narrow pitch, have a high wiring density, have good heat radiation, and handle high-speed signals. It is required that the number of input / output terminals of the package can be increased and the pitch can be reduced. Further, there is a need for a technique for producing a high-performance package satisfying these conditions at a low cost with a simple process and high reliability.

[0004] In order to enhance the function of a semiconductor element, three pillars, ie, multi-bit, large capacity, and high speed are the pillars. For example, demands for higher speeds have had a significant impact on packages. This is because the number of input / output terminals (the number of pins) to the semiconductor element is increased and data is processed in parallel to increase the speed. For this reason, multi-terminals (multi-pins) has become one proposition in packages. In addition, the miniaturization of portable devices and the miniaturization of packages for high-density mounting are also required. This demand is particularly great in the field of multimedia, amusement and communication equipment, which will greatly increase in the future.

[0005] Various packages have been developed to satisfy the two needs of increasing the number of pins and reducing the size. In order for the connection technology with the semiconductor chip to function effectively, the package side must also have a narrow-pitch, multi-terminal inner lead part, and the connection between the mounting board, such as a printed circuit board, and the package must be a multi-terminal, narrow terminal. It is necessary to be on the pitch. Further, as described above, the package needs to handle high-speed signals due to the increase in the speed of the LSI, so that it is necessary to consider the electrical characteristics.

[0006] In order to satisfy the above demands for a package having multiple terminals and a narrow pitch, the package structure has been changed from a conventional pin insertion type or a surface mount type such as a QFP (Quad Flood Package). , BGA
(Ball Grid Array) package. In order to increase the number of terminals and reduce the pitch, the conventional surface mount type has seen limitations in terms of terminal accuracy, inductance caused by leads, strength of the leads themselves, and accuracy during mounting. is there. Also, the surface mount type has a disadvantage that the package must be increased in size as the number of terminals increases.

[0007] BGA can reduce the inductance compared to conventional packages and can adapt the multilayer wiring structure of the package body at high speed, and is used for consumer products such as large computers, personal computers, and portable devices. Is spreading. BGA is a protruding connector (solder ball) made of solder as the input / output terminal of the package
It is possible to improve the reflection delay of a high-speed signal and the like due to the inductance caused by the pins and leads as described above. Further, in addition to shortening of the connection distance by the solder ball, narrow pitch and multiple terminals can be easily achieved by forming the solder ball.
Promising as an SI package. Furthermore, the narrow pitch and multiple terminals due to the formation of the solder balls reduce the package size itself, improve the mounting density on printed circuit boards, etc., improve the electrical characteristics by reducing the parasitic capacitance, inductance, and resistance of wiring, and improve the package. Improvement of high frequency characteristics and the like can be expected by downsizing. On the other hand, from the viewpoint of the heat radiation of the package, the power consumption increases and the heat generation tends to increase year by year as the integration density and the speed of the LSI increase. Moreover, in the computer, while the size of the main body has been reduced, the number of boards has been increasing, and the gap between the boards has been gradually narrowed.

[0008] For these reasons, the package itself is required to be thin and to have a structure and material excellent in heat dissipation. Ceramic packages are mainly used for high heat dissipation packages. Ceramics include aluminum nitride, silicon nitride, alumina, glass ceramics and the like, and these are properly used depending on the specifications such as the calorific value and high frequency characteristics. However, the ceramic package has a problem that when mounted on a printed circuit board, the connection reliability of the solder ball portion, which is a connection portion, is low because the difference in thermal expansion coefficient between the package and the printed circuit board is large. I have. This difference in thermal expansion can be caused by thermal history in the reflow soldering process when mounting the BGA package on a printed circuit board, or by a change in environmental temperature during normal use. Due to the large difference in thermal expansion from the printed circuit board, thermal stress concentrates on the solder balls with low mechanical strength, causing cracks in the solder balls and breaking the solder balls. There was a problem that the property was reduced.

In view of this problem, in recent years, reliability has been improved by forming a composite package in which a resin substrate having a thermal expansion coefficient close to that of a printed substrate is bonded to a ceramic substrate with an adhesive or the like. In other words, by using a composite package in which ceramics with high thermal conductivity and a resin with a wiring layer are bonded together and electrically and mechanically bonded, the thermal expansion coefficient of the resin substrate and the ease of fine wiring by screen printing or lithography It has a structure that takes advantage of the advantages of the low cost of the resin substrate and the high thermal conductivity of the ceramic substrate.

[0010] In general, a resin substrate constituting a composite package is often used as a connection via in such a manner that projecting bumps penetrate the resin. For example, as shown in Preliminary edition 15A-10, pp. 55-56 of the 9th Circuit Packaging Academic Performance Conference, 1994, the Circuit Packaging Society of Japan, copper foil and copper are sandwiched between a bump and a resin. Direct bonding with foil has been performed. At this time, since it is necessary to break through the oxide film on the copper surface, the joining load must be increased.

[0011]

However, in the case of a composite package in which a ceramic substrate and a resin substrate are connected to each other at a connection pad portion, a strong pressure cannot be applied as described above. This is because it leads to breakage of the ceramics. Therefore, there is a need for a composite package structure and a method of manufacturing the same that can make electrical connection at the connection pad portion even at a low pressure different from the conventional one.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a thin and highly reliable composite package of a resin substrate and a ceramic substrate which enables good electrical connection at a connection pad portion.

Another object of the present invention is to provide a composite package for a semiconductor device which can provide good electrical and mechanical connection even when the pressure at the time of bonding a resin substrate and a ceramic substrate is reduced.

Still another object of the present invention is to provide a highly reliable semiconductor device capable of making a good electrical connection at a connection pad portion despite using a contact structure between a thin resin substrate and a ceramic substrate. A method of manufacturing a composite package is provided.

Still another object of the present invention is to provide a method of manufacturing a composite package for a semiconductor device in which the pressure at the time of bonding a resin substrate and a ceramic substrate is reduced.

[0016]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and as a result, have found that gold (A) is formed on the surface of a connection pad for bump connection between a resin substrate and a ceramic substrate.
u) It has been found that this can be achieved by coating a thin film.

That is, a first feature of the present invention is that a ceramic substrate having a first connection pad portion, a resin substrate having a second connection pad portion, and a projection for connecting the first and second connection pad portions are provided. A composite package for a semiconductor device having a bump and a first and second connection pad portion covered with a gold (Au) thin film.

According to the first aspect of the present invention, since the coating with the gold (Au) thin film is provided on the first and second connection pad portions, the first and second connection pad portions are not oxidized, and the first and second connection pad portions are not oxidized. Unlike the case of joining metals such as aluminum and aluminum, the first connection pad portion and the second connection pad portion can be connected with a good electrical connection with a small pressure.

The resin used for the resin substrate is preferably a resin having a strong strength itself, such as a liquid crystal polymer, a BT resin, or a resin containing a fibrous sheet. The bumps constituting the resin substrate are made of silver (Ag), platinum (P
t), gold (Au), or an alloy containing at least one of these alloys may be used.

The ceramic substrate according to the first aspect of the present invention is preferably made of any one of alumina, aluminum nitride, silicon nitride, silicon carbide, boron nitride, and diamond. Further, a composite ceramics substrate composed of at least two of these may be used.

The thickness of the gold thin film is 0.03 μm or more,
Desirably, the thickness is 0.1 μm or more and 100 μm or less. The upper limit of the gold thin film may be appropriately selected from the viewpoint of manufacturing cost and the like.

A second feature of the present invention is a step of coating a connection pad portion (second connection pad portion) of a resin substrate with a thin film of first gold (Au); a connection pad portion (first connection portion) of a ceramic substrate. Coating a second gold (Au) thin film on the connection pad portion); joining pressure of 10 kgf / cm between the resin substrate and the ceramic substrate via the bumps
It is a method of manufacturing a composite package for a semiconductor device, which includes at least a bonding step of ² or less.

According to the manufacturing method of the second aspect of the present invention, since the connection pad portion is coated with a gold (Au) thin film, the connection pad portion is not oxidized, and the connection time between metals such as copper and aluminum is reduced. The difference is that the connection pad portion on the resin substrate side and the connection pad portion on the ceramic substrate side are connected with good electrical connectivity with a small pressure of 10 kgf / cm ² or less, preferably 5 kgf / cm ² or less. Can be done.

In the second aspect of the present invention, the thickness of the gold thin film is preferably at least 0.03 μm, particularly preferably at least 0.1 μm.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a schematic sectional view of a 300-pin composite package for a semiconductor device according to an embodiment of the present invention, and FIG. 1B is an enlarged view of a portion A in FIG. 1A. As shown in FIGS. 1A and 1B, in a composite package for a semiconductor according to an embodiment of the present invention, a ceramic substrate 11 and a resin substrate 10 are bonded via an adhesive 13. The resin substrate 10 includes a silver bump 22 therein and has copper foils 31, 34, 35 on both sides. The copper foil is patterned so as to form a surface wiring 35 such as an input / output pad and a land 31 serving as a second connection pad portion, and gold plating layers 41 and 44 are formed on the surface thereof. The semiconductor chip 1 is connected to the cutout (cavity) of the resin substrate via the conductive adhesive 61 by the ceramic substrate 11.
Mounted on top.

The resin substrate 10 has a structure in which a liquid crystal polymer 23 is a main component and copper foils 31 and 35 are bonded to both sides thereof.
The thickness of the liquid crystal polymer layer 23 is 0.035 mm. In addition, as the resin substrate 10, one using BT resin, one using glass epoxy resin, or the like may be used.

Also, in order to obtain high heat radiation characteristics, aluminum nitride ceramics was used as the material of the ceramic substrate 11. The thermal conductivity of aluminum nitride is 180 W /
m · K. The thickness of the ceramic substrate 11 is 0.6 mm
And the external dimensions are 31 mm □. Ceramic substrate 11
Are formed inside, and the through-hole metal 12 is embedded with connection pad portions (lands) 39 provided at both ends. The land 39 at the upper end becomes the first connection pad section of the present invention. In addition, as the material of the ceramic substrate 11, any of alumina, silicon nitride, silicon carbide, boron nitride, and diamond may be used.

An acrylic adhesive is used as the adhesive, and the bonding pressure between the resin substrate 10 and the ceramic substrate 11 is 2 kgf.
/ Cm ² .

In the embodiment of the present invention shown in FIG. 1, a 0.2 μm Au plating layer 51 is formed on the second connection pad portion 31 of the resin substrate 10 with the Ni plating layer 41 as a base.
The connection pad portion (first connection pad portion) 39 of the ceramic substrate 11 is coated with a Ni plating layer 4.
The Au plating layer 55 is coated with a thickness of 0.2 μm through the layer 5. As shown in FIG. 1B, the bump 2 exists between the Au plating layer 51 of the second connection pad and the Au plating layer 55 of the first connection pad.

[0030]

[Table 1] The above table shows the comparison of the electrical connection failure rate with the comparative example in order to clarify the effect of the present invention. In the structure of the comparative example, the second connection pad portion of the resin substrate and the first connection pad portion of the ceramic substrate were not coated with Au. Other structures and conditions are exactly the same as those of the above embodiment. It was found that the application of the Au coating improved the electrical connection failure rate from 4% to 0%.

Next, a method of manufacturing a composite package for a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS.

(A) First, as shown in FIG.
A 100 μm silver bump 22 is formed on a portion corresponding to a semiconductor input / output pad by a silver epoxy conductive paste and a portion corresponding to a land of a package body.
To form

(B) Next, a liquid crystal polymer 23 having a thickness of 35 μm is covered with the tip of the silver bump so that it can easily break through.
As shown in (b), the copper foils 21 and 24 are laminated so as to be on both sides, and laminated by applying temperature and pressure. Thereafter, as shown in FIG. 2C, a cavity window 77 for mounting the semiconductor chip is punched out by a press to form a hole.

(C) Thereafter, as shown in FIG. 2D, the copper foil portion is etched to form the front surface wiring 35 on the front surface, and the connection pad portion (the second connection pad portion) called a land is formed on the back surface. Part) 31 is formed. Thereafter, a solder resist is formed on the surface layer by printing.

(D) Subsequently, as shown in FIG. 2 (e), nickel plating (Ni) is applied to the surface wiring 35 and the Ni plating layers 44 and 41 on the lands (second connection pad portions) 31.
To form Further, as shown in FIG.
Plating is performed to form Au coating layers 51 and 54 on the Ni plating layers 41 and 44, thereby completing the resin substrate 10.

(E) On the other hand, a ceramic green sheet 11 is prepared, a through-hole is opened as shown in FIG. 3A, a through-hole metal 12 is buried, and connection pad portions (first Land 3 to be connection pad
9 is formed. Following the degreasing and firing of the ceramic, the Ni plating layer 4 is formed on the surface of the land 39 as shown in FIG.
5 is formed. Further, as shown in FIG. 3C, an Au coating layer 55 is formed on the surface of the Ni plating layer 45 by Au plating, and the ceramic substrate 11 is completed.

(F) Next, a silver epoxy-based paste is selectively formed on the land (first connection pad portion) 39 of the ceramic substrate 11 which needs to be electrically connected to the resin substrate 10 by a screen printing technique. Then, drying is performed to form the projection bumps (silver bumps) 2 on the gold coating layer 55 of the land portion 39. After that, if the acrylic adhesive sheet 13 is sandwiched between the ceramic substrate 11 and the resin substrate 10 and the resin substrate 10 and the ceramic substrate 11 are joined at a joining pressure of 2 kgf / cm ² , the semiconductor according to the embodiment of the present invention can be obtained. The composite package for the device is completed. Instead of the acrylic adhesive sheet 13, an acrylic adhesive may be applied to the surface of the ceramic substrate 11 to bond the resin substrate 10 and the ceramic substrate 11. In general, when an acrylic adhesive is used, good electrical characteristics cannot be obtained unless about 15 kgf / cm ² is used.
Good electrical connection can be obtained even in cm ² .

In the above description of the steps, the Au coating layer is formed by plating, but may be formed by vacuum deposition or sputtering other than plating. In this case, the underlying Ni plating layers 41, 44, 45 can be omitted. The resin substrate 10 and the ceramic substrate 11 may be bonded using an epoxy-based adhesive. In the case of an epoxy adhesive, in the prior art, 20 to 40 kgf / cm
According to the present invention, it was necessary to bond with a pressure of ^2.
Good electrical connection can be obtained even when the adhesive is applied at a pressure of kgf / cm ² .

As described above, the present invention has been described with reference to the above embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art. For example, even in the cavity-down type composite package shown in FIG.
In the case where the wiring layer includes the first wiring layer, the wiring layer has a function equivalent to the first connection pad. Therefore, Au is formed on the surfaces of these wiring layers 61 and the connection bump portions 31 of the resin substrate.
If the coat layers 55 and 51 are formed, the ceramic substrate 1
A good connection between the second connection bump portion 31 and the wiring layer 61 is obtained. Further, as shown in FIG. 5, the resin substrate 90 may have a multilayer structure. The resin substrate 90 shown in FIG. 5 has a two-layer structure in which an upper silver bump 22a and a lower silver bump 22b are connected via a copper foil. Also in this case, the multilayer resin substrate 9
The surfaces of the connection pad portion (second connection pad portion) 31 and the connection pad portion 39 (first connection pad portion) of the ceramic substrate 11 may be covered with the Au coat film 55. Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the matters specifying the invention described in the claims that are reasonable from this disclosure.

[0040]

As described above, according to the present invention, a composite package having high electrical connection reliability can be obtained.

Further, according to the present invention, since the pressure at the time of bonding is low, the ceramic which is a brittle material is not cracked at the time of bonding, so that the production yield is improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of a composite package for a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a process cross-sectional view for explaining a method of manufacturing a composite package for a semiconductor device according to an embodiment of the present invention (part 1).

FIG. 3 is a process sectional view explaining the method for manufacturing the composite package for semiconductor device according to the embodiment of the present invention (part 2).

FIG. 4 is a schematic sectional view of a composite package for a semiconductor device according to another embodiment of the present invention.

FIG. 5 is a schematic sectional view of a composite package for a semiconductor device according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Protrusion bump 3 Solder ball 10,90 Resin substrate 11 Ceramic substrate 12 Oxide layer 13 Adhesive 21,24 Copper foil 22,22a, 22b Protrusion bump (silver bump) 23 Liquid crystal polymer 31,39 Connection pad part ( Land) 33 Copper foil 35 Surface wiring (input / output pad) 41,44 Ni plating layer 51,54,55 Gold (Au) coating layer 61 Ground layer 77 Window

Claims (5)

[Claims] 1. A composite package comprising a ceramic substrate having a first connection pad portion, a resin substrate having a second connection pad portion, and a projection bump connecting the first and second connection pad portions. A composite package for a semiconductor device, wherein the first and second connection pad portions are covered with a thin gold film. 2. The composite package for a semiconductor device according to claim 1, wherein said ceramic substrate is any one of alumina, aluminum nitride, silicon nitride, silicon carbide, boron nitride, and diamond. 3. The composite package for a semiconductor device according to claim 1, wherein said gold thin film has a thickness of 0.03 μm or more. 4. A step of coating the connection pad portion of the resin substrate with a first gold thin film; a step of coating the connection pad portion of the ceramic substrate with a second gold thin film; Bonding at a bonding pressure of 10 kgf / cm ² or less via a projection bump. 5. The method according to claim 4, wherein the thickness of the first and second gold thin films is 0.03 μm or more.