JPH0371649A - Semiconductor integrated circuit and manufacture thereof - Google Patents

Abstract

PURPOSE:To surely prevent the positional deviation of a chip due to mechanical vibration induced at the transfer of a board by a method wherein low melting point controllable collapse bonding(CCB) bumps are fused by heating to fix a chip temporarily to a board, and then the rest of the CCB bumps are fused by heating to mount the chip on the board. CONSTITUTION:CCB bumps 9a out of CCB bumps 9 are formed of material whose melting point is lower than that of material which forms the rest of the CCB bumps 9, and only the low melting point CCB bumps 9a are fused by heating to temporarily fix a chip 5 to a board 10 when the chip 5 is positioned on the board 5 by a chip mounting device 14, and the rest of the CCB bumps 9 are melted by heating in a reflow device to mount the chip 5 on the board 10. Therefore, the positional deviation of the chip 5 can be prevented from occurring due to mechanical vibrations induced at the transfer of the board 10 from the chip mounting device 14 to the reflow device. By this setup, the connection failure of CCB bumps can be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor integrated circuit device and a method for manufacturing the same, and particularly to a semiconductor integrated circuit device and a method for manufacturing the same.
The present invention relates to a technique that is effective when applied to a blip-chip type semiconductor integrated circuit device in which a semiconductor chip is mounted on a substrate via bumps.

[Conventional technology]

Logic LSI such as gate arrays and microcomputers
As integrated circuits become more multi-functional and denser, the number of terminals (input/output pins) used to connect with external circuits rapidly increases, and wires are connected to bonding pads on the periphery of semiconductor chips. The wire bonding method, which connects the internal circuit to the external circuit, has reached its limit.In addition, the wire bonding method routes the wiring in the internal area to the bonding pad on the skin, which increases the length of the wiring, making it difficult to transmit signals. Since this method has the disadvantage of slow speed, it is not suitable as a mounting method for logic LSIs that require high-speed operation.

For these reasons, the so-called flip-chip method is attracting attention, in which a CCB bump (protruding electrode) made of solder or the like is bonded to the topmost wiring of an integrated circuit, and a semiconductor chip is mounted on a substrate via this CCB bump. has been done. This flip-chip method has the advantage that terminals can be provided not only in the periphery of the chip but also in the internal region, so that the number of pins on the chip can be increased. Furthermore, the flip-chip method has the advantage that the length of wiring on the chip can be made shorter than that of the wire bonding method, so that the speed of the logic LSI can be increased. Regarding the above prep chip method, for example, IBM
Published by rTBM Journal of Research and Development.

Volume 13, Ha 3 (IBM Journal o
fResearch and Development
t, Vol, 13. No. 3) JP 239~P
250 has a detailed description.

[Problem to be solved by the invention]

To mount a chip onto a board via CCB bumps, first position the chip at a predetermined location on the board using a chip mounting device, then transfer the board to a reflow device and heat the CCB bumps in an inert atmosphere. A melting (reflow) method is used.

However, when the substrate is transported from the chip mount device to the reflow device, the chip positioned on the substrate may be misaligned due to mechanical vibration, etc., and the CCB
There is a problem that poor connection of bumps occurs. As a countermeasure, there is a method of temporarily fixing the chip to the substrate using 7lux when positioning the chip on the substrate, but this method has the problem that the flux becomes a source of contamination of the chip and the electrical characteristics of the chip deteriorate over time. There is. Another method is to temporarily fix the chip to the substrate by heating the CCB bumps at a temperature below their melting point while applying a load from the back side of the chip when positioning the chip on the substrate. There is a problem that the electrical characteristics of the chip deteriorates due to the additional damage, and a problem that the bonding strength of the CCB bump decreases because the surface of the CCB bump is oxidized when the CCB bump is heated.

The present invention has been made focusing on the above-mentioned problems,
The purpose is to provide a technique that can improve the connection reliability of solder bumps.

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

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

One invention of the present application is to construct a part of the CCB bump in advance from a material with a lower melting point than the remaining CCB bumps, and heat only the low melting point CCB/imp when positioning the chip on the substrate using a chip mount device. After temporarily fixing the chip to the substrate by melting, the remaining CCB bumps are heated and melted in a reflow device to mount the chip on the substrate.

[Operation: According to the above means, when positioning the chip on the substrate using the chip mount device, the low melting point CCB bumps are heated and melted to temporarily fix the chip to the substrate, so that the substrate can be removed from the chip mount device. Since it is possible to prevent the chip from being misaligned due to mechanical vibration during transport to the flow device, it is possible to reliably prevent poor connection of the CCB bumps. In addition, the temperature when heating and melting the low-melting point CCB bumps to temporarily fix the chip to the substrate is much lower than the melting point of the remaining CCB bumps, so the surface is hardly oxidized, which improves the bonding strength of the CCB bumps. does not decrease.

Hereinafter, the present invention will be explained in detail using Examples.

〔Example〕

The semiconductor integrated circuit device of this embodiment is a microchip carrier (Micro Chip Carrier;
CC).

As shown in FIG. 1, this microchip carrier 1 has a semiconductor chip 5 face-down bonded onto lands 4 of a mullite substrate 3 via CCB bumps 2, and a cap made of, for example, aluminum nitride (AJN). It has a hermetically sealed structure. The cap 6 is bonded onto the mullite substrate 3 by sealing solder 7 provided on the shoulder edge of the mullite substrate 3. The back surface (top surface) of the chip 5 is connected to a cap 6 via heat transfer solder 8.
The structure is such that the heat generated from the chip 1 is dissipated to the outside through the cap 6. Although not shown, a heat sink may be bonded onto the cap 6 to improve heat dissipation efficiency.

The CCB bump 2 is made of a Pb/Sn alloy containing about 2% by weight of Sn, and its melting point is 320~320%.
The temperature is about 330°C. On the other hand, the sealing solder 7 and the heat transfer solder 8 both contain P containing about 5% by weight of Ag.
b/Sn/Ag alloy, and in this embodiment, some of the CCB bumps 2a of the CCB bumps 2 are made of a low melting point material. C like this
The number of CB bumps 2a is, for example, about 1 to 4. The low melting point CCB bump 2a is made of, for example, about 25% by weight of In.
(indium) and about 17% by weight of Sn
(Bismuth) alloy, and its melting point is about 80 or higher.

The lands 4 provided on the lower surface of the mullite substrate 3 include
A CCB bump 9, which is larger in rotation than the CCB bump 2.2a, is bonded, and a microchip carrier 1 is mounted on the land 11 of the module board IO via this CCB bump 9. The CCB bump 9 is made of a Pb/Sn alloy containing about 30% by weight of Sn, and its melting point is about 250 to 260°C.

The CCB bump 9 is connected to the CCB bump 9 through an internal wiring 12 made of W (tungsten) or the like provided in the mullite substrate 3.
Bump 2, furthermore chip 1 and electric CCB bump 2a,
It is not electrically connected to the chip 1, nor is it electrically connected to the internal wiring 12 of the mullite substrate 3. That is, the CCB bump 2a is a dummy bump that does not function as an electrode. Furthermore, in this embodiment, some of the CCB bumps 9a of the CCB bumps 9 for mounting the microchip carrier 1 on the module substrate 10 are made of a low melting point material. CC like this
The number of B bumps 9a is, for example, about 1 to 4. The low melting point CCB bump 9a contains about 25% by weight of In (indium) and 17% by weight, the same as the low melting point CCB bump 2a.
It is made of a Bi (bismuth) alloy containing a certain amount of Sn,
Its melting point is about 80 or higher. The CCB bumps 9a are not electrically connected to the wiring (not shown) on the module board 10, nor are they electrically connected to the internal wiring 12 of the mullite board 3. That is, the CCB bumps 9a
Like the CCB bumps 2a, they are dummy pans that do not function as electrodes.Next, a method for assembling the microchip carrier 1 will be described.

First, the chip 5 shown in FIG. 2 and the mullite substrate 3 shown in FIG. 3 are prepared. As shown in FIG. 2, a large number of CCB bumps 2 are provided on the integrated circuit forming surface of this chip 5. Each of the CCB bumps 2 is electrically connected to internal wiring of the chip 5 via a base electrode (not shown). Further, on the integrated circuit forming surface of this chip 5, for example, three base electrodes 13 to which the CCB bumps 2 are not connected are provided. These base electrodes 13 are all dummy base electrodes that are not electrically connected to the internal wiring of the chip 5.

On the other hand, as shown in FIG. 3, lands 4 are provided on the chip mounting surface of the mullite substrate 3 at positions corresponding to each of the CCB bumps 2. Among these lands 4, the base electrode 13 to which the CCB bump 2 is not connected
The low melting point material is placed on the lands 4 provided at positions corresponding to each of the lands 4. The lands 4 to which the CCB bumps 2a are bonded are all dummy lands that are not electrically connected to the internal wiring 12 of the mullite substrate 3.

Next, as shown in FIG.
Accurately position it on land 4. Then, at this time, the chip 5 is temporarily fixed on the mullite substrate 3 by heating the mullite substrate 3 to about 90 to 100° C. to melt the low melting point CCB bumps 2a. Subsequently, the mullite substrate 3 is transferred from the chip mounting device 14 to the reflow device 15 shown in FIG. Then, the mullite substrate 3 is heated to 350°C while the inside of the reflow apparatus 15 is kept in an inert atmosphere.
The chip 5 is mounted on the mullite substrate 3 by heating to a certain degree to melt the CCB bumps 2. Thereafter, the cap 6 is bonded to the mullite substrate 3 via the sealing solder 7, and the back surface of the chip 5 is bonded to the back surface of the cap 6 via the heat transfer solder 8, as shown in FIG. The microchip carrier 1 is completed.

Next, in order to mount the microchip carrier 1 on the module substrate 10, first, as shown in FIG. 6, the microchip carrier 1 is accurately positioned on the module substrate 10 using the chip mounting device 14. CCB bumps 9 are bonded in advance to the lands 4 provided on the lower surface of the mullite substrate 3 of the microchip carrier 1, and on the other hand, among the lands 11 on the module substrate 10,
A low melting point CCB bump 9a is bonded in advance to the dummy land lla which is not electrically connected to the internal wiring. Then, the microchip carrier 1 is temporarily fixed on the module substrate 10 by heating the module substrate 10 to about 90 to 100° C. in the chip mounting device 14 to melt the low melting point CCB bumps 9a, and then the module substrate 10 is temporarily fixed on the module substrate 10. The substrate 10 is mounted on the chip mount device 14
The module substrate 10 is transferred from
By heating the CCB bumps 9 to about 280° C. to melt the CCB bumps 9, the mounting structure shown in FIG. 1 is completed.

According to this embodiment having the above configuration, the following effects can be obtained.

(1) When positioning the chip 5 on the mullite substrate 3 using the chip mounting device 14, the low melting point CCB bump 2a is heated and melted to temporarily fix the chip 5 on the mullite substrate 3, and then reflow mounting! Since the CCB bumps 2 are heated and melted in the reflow device 15, it is possible to reliably prevent the chip 5 from shifting due to mechanical vibrations when the mullite substrate 3 is transported from the chip mount device i4 to the reflow device 15.

(2) The temperature at which the low melting point CCB bump 2a is heated and melted in the chip mount device 14 (90 to 100°C) is much lower than the melting point of the CCB bump 2 (320 to 330°C), so the CCB/ The surface of the ink 2 is hardly oxidized, so the bonding strength thereof does not decrease.

(3) According to (1) and (2) above, the connection reliability of the CCB bump 2 when mounting the chip 5 on the mullite substrate 3 via the CCB bump 2 is improved, so that the microchip carrier 1 Reliability and manufacturing yield are improved.

(4) Chip mount! 14 to position the microchip carrier 1 on the module substrate 10 , the low melting point CCB bumps 9 a are heated and melted to temporarily fix the microchip carrier 1 on the module substrate 10 , and then the CCB bumps 10 are temporarily fixed on the module substrate 10 in the reflow device 15 . Since the bumps 9 are heated and melted, the module substrate 10 is mounted on the chip mounting device 14.
It is possible to reliably prevent the microchip carrier 1 from being misaligned due to mechanical vibrations during transportation from the microchip carrier 1 to the reflow apparatus 15.

(5) The temperature (90 to 100°C) when heating and melting the low melting point CCB bump 9a in the chip mount device 14 is as follows:
Since it is much lower than the melting point (250 to 260° C.) of the CCB bump 9, the surface of the CCB bump 9 is hardly oxidized, and therefore its bonding strength does not decrease.

(6), By (4) and (5) above, the microchip carrier 1 is connected to the module substrate 10 via the CCB bump 9.
Since the connection reliability of the CCB bumps 9 when mounted thereon is improved, the reliability of the semiconductor integrated circuit device having a module structure and its manufacturing yield are improved.

As above, the invention made by the present inventor has been specifically explained based on Examples, but the present invention is not limited to the above-mentioned Examples, and it is understood that various changes can be made without departing from the gist thereof. Needless to say.

Although the low melting point CCB bumps in the above embodiments were dummy bumps that did not function as electrodes, a portion of the CCB bumps that functioned as electrodes may be replaced by low melting point CCB bumps. Further, in the above embodiments, the low melting point CCB bumps were provided on the upper surface of the mullite substrate and the upper surface of the module substrate, but they may be provided on the integrated circuit forming surface of the chip or the lower surface of the mullite substrate.

The embodiments described above can be applied to all flip-chip type semiconductor integrated circuit devices in which chips are mounted on various substrates via suitable bumps on microchip carriers.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

That is, a part of the CCB bump is made of a material with a lower melting point than the remaining CCB bump, and when the chip is positioned on the substrate using a chip mounting device, the low melting point CCB
According to the present invention, the chip is temporarily fixed to the substrate by heating and melting only the bumps, and then the remaining CCB bumps are heated and melted in a reflow apparatus to mount the chip on the substrate. CCB
Improves bump connection reliability.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts of a semiconductor integrated circuit device which is an embodiment of the present invention, FIG. 2 is a plan view of a semiconductor chip, FIG. 3 is a plan view of a mullite substrate, and FIGS. FIG. 6 is a sectional view of a main part showing a method of manufacturing this semiconductor integrated circuit device. 1... Microchip carrier, 2.2a. 9.9a...CCB bump, 3...Mullite substrate,
4.11. lla...Land, 5...Semiconductor chip, 6...Cap, 7...Solder for sealing, 8...Solder for heat transfer, 10...Module board, 12...Internal wiring , 13... Base electrode, 14... Chip mount device, 15... Reflow device. Figure 2 Figure 3 Figure

Claims (1)

[Claims] 1. A semiconductor integrated circuit device in which a semiconductor chip is mounted on a substrate via CCB bumps, wherein a part of the CCB bumps is made of a material having a lower melting point than the remaining CCB bumps. Features of semiconductor integrated circuit devices. 2. The semiconductor integrated circuit device according to claim 1, wherein the low melting point CCB bump is a dummy bump having no function as an electrode. 3. When positioning the semiconductor chip on the substrate using a chip mounting device, the low melting point C of the CCB bumps is used.
3. The semiconductor chip is temporarily fixed to the substrate by heating and melting only the CB bumps, and then the remaining CCB bumps are heated and melted in a reflow apparatus to mount the semiconductor chip on the substrate. A method of manufacturing the semiconductor integrated circuit device described above. 4. The method of manufacturing a semiconductor integrated circuit device according to claim 3, wherein the low melting point CCB bump is provided on the substrate side.