JPH08330352A - Semiconductor device - Google Patents

Abstract

PURPOSE: To provide a highly reliable package having low thermal resistance and temperature cycle resisting property at low cost. CONSTITUTION: A flip chip is connected to a glass epoxy substrate 1 by soldering, and the inside of a chip pad and the substrate are adhered by heat conductive and thermoplastic resin. Also, the cap 7 of a metal or glass epoxy substrate is adhered using heat conductive and thermoplastic resin, and the circumference of the cap 7 is adhesively sealed by heat conductive and thermoplastic resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a flip chip type semiconductor device using a resin circuit board.

[0002]

2. Description of the Related Art As a first example of a conventional semiconductor device having a flip-chip structure, FIGS. 4A and 4B described in "Direct attachment method of semiconductor chip to substrate" of Japanese Patent Laid-Open No. 4-234139. ), (C), (D), and (E) are cross-sectional views to describe the manufacturing method. First, in FIG. 6A, solder bumps or polyimide-siloxane gold composite material bumps 24 are formed on each electrode on the main surface of the semiconductor chip 28, and an insert material 19 is prepared separately. Here, the method for manufacturing the polymer insertion material 19 includes a thermoplastic dielectric elastomer such as silicon having a thickness of 200 to 250 μm, a thermoplastic dielectric polymer, a copolymer such as polyimide and siloxane, or various other polymers and copolymers. A polymer sheet is prepared, a weak adhesive 16 is applied to one side of the sheet, further covered with a protective sheet 14, and a strong adhesive 15 is applied to the opposite side. Next, holes 13 are formed in this sheet by punching or laser irradiation in accordance with the arrangement pitch of the pumps 24 of the semiconductor chip 28 and the bump diameter. The protective sheet 14 having the holes 13 and the polymer insertion material 19 are cut to the same size as the semiconductor chip 28, and the surface of the sheet having the strong adhesive 15 applied is aligned with the chip surface as shown in FIG. To glue. At this time, the holes 13 formed in the sheet are positioned so as to fit the solder bumps 4 of the semiconductor chip 28.

In each hole 13 of this sheet, a composite paste 30 formed by mixing a conductive fine metal with a thermoplastic polymer such as copolymerized polyimide-siloxane is formed by screen printing. Next, as shown in (C), the protective sheet 14 is peeled off to expose the weak adhesive layer 16. In (D), the paste applied on the chip pads is positioned with respect to the paste bumps of the circuit board 23. In the next step (E), pressure is applied to the substrate 23 and the chip 28 to join them.

Next, as a second example of a conventional semiconductor device having a flip-chip structure, FIGS. 5A and 5B described in "Sealing Method of Semiconductor Device and Semiconductor Chip" in Japanese Patent Laid-Open No. 3-12942. ), (C). First, in FIG. 5A, a resist is applied, exposed, and developed on the semiconductor chip 28 in the state of a semiconductor wafer to open the portion of the chip electrode 26. Next, solder plating is applied to form solder bumps 24 on the electrodes 26. After that, the thermoplastic resin 29 is applied by spin coating and is temporarily cured by heating. In this state, the semiconductor wafer is diced and the semiconductor chip 28 is prepared. 5B for explaining a method of connecting the semiconductor chip 28 to the circuit board 23, the circuit board 23 placed on the hot plate 21 is
The semiconductor chip 2 adsorbed by the bonding tool 20
8 facing each other, and solder bumps 24 with a flip chip bonder.
And the substrate electrode 22 are aligned. Next, FIG. 5 (C)
As shown in, the bonding tool 20 is lowered to bring the chip electrode 26 into contact with the substrate electrode 22 and pressurize it. The temperature of the hot plate 21 is raised to a temperature at which the solder 4 is melted, so that the solder 4 is melted and connected.

[0005]

However, in the first conventional example described above, the holes 13 of the thermoplastic polymer sheet having a thickness of 200 to 250 μm are filled with the thermoplastic polyimide-siloxane / gold composite material. And the electrical connection with the electrodes of the circuit board 23 is made by the semiconductor chip 28.
Adhesive 16 adhered to the polymer insert 19 of
Since the pressure resistance is only connected by pressure welding, there is a concern that the contact resistance may change over time due to a temperature cycle or the like, and the reliability of the connection may deteriorate.

It is considered that the chip 28 can be removed from the surface of the polymer sheet which is adhered to the substrate 23 by heating, but the broken state of the thermosetting polyimide-siloxane / gold composite material filled in the hole 13 is removed. If the surface is not evenly peeled from the substrate electrode surface, it will be difficult to regenerate the module.

Regarding the above-mentioned second conventional example,
Although the solder 24 is attached to the chip electrode 26, the thermoplastic resin 29 is applied to the entire surface of the chip including the solder surface. In this structure, when the heating connection is performed, the resin 29 is sandwiched between the substrate electrode 22 and the chip electrode (solder) 26, and a perfect connection cannot be made. Even if the resin 29 is connected, the connection resistance may vary.

Further, in the above-mentioned first and second conventional examples, an appropriate material for the circuit board is not described. Depending on what is selected for this material, the electrode connection portion is destroyed in a thermal stress test such as a temperature cycle. There is a risk of The reason for this is that when glass epoxy is used as the substrate material, the coefficient of thermal expansion is 2
00 × 10 ^-7 , the semiconductor chip is 24 × 10 ^-7 , and if the resin or polymer sheet described above is sandwiched in the gap between the substrate and the chip, the electrode connection part may be destroyed due to stress such as temperature cycle. , Reliability cannot be maintained.

Further, as protection of the semiconductor chip, it is desired to supply a semiconductor device having a low thermal resistance, which is only to the extent of being coated with a resin, and which secures moisture resistance and improves heat dissipation.

In view of the above problems, the present invention has the following problems.

(1) To improve the electrical and mechanical connection between the electrode on the main surface of the semiconductor chip and the counter electrode on the circuit board.

(2) To prevent the contact resistance of the connecting portion from increasing and the joining force from decreasing due to temperature cycle or the like.

(3) To facilitate removal and reconnection of the semiconductor chip.

(4) The connection resistance should not vary and the connection should be uniform.

(5) In a thermal stress test such as a temperature cycle, prevent the connecting portion from being destroyed.

(6) To secure moisture resistance and improve heat dissipation.

(7) The structure should have a low thermal resistance.

(8) Even if a material having a large difference in thermal expansion is used,
Make sure the bump connection is not destroyed.

(9) To improve the reliability of the connection portion, and thus to improve the reliability of the semiconductor device.

[0020]

According to the first semiconductor device of the present invention, a concave cavity is formed on the back surface of an insulating substrate, and external bumps or external lead pins are formed on the back surface around the cavity. An inner bump formed on the bottom surface of the cavity and an electrode of the semiconductor chip, the bottom surface of the cavity being fixed to the main surface of the semiconductor chip with a first resin, being electrically connected to the external bump or the external lead pin Are solder-connected, the back surface of the semiconductor chip and the cap are fixed with a second resin, and the cap and the cavity are fixed with a third resin.

In particular, the bottom surface of the cavity is made of a heat radiation metal, and the heat radiation metal and the cap are made of the same material.

In particular, a large number of heat radiation vias are formed on the bottom surface of the cavity.

According to the second semiconductor device of the present invention, internal bumps are formed on the main surface of the insulating substrate, and external bumps or external lead pins electrically connected to the internal bumps are formed on the back surface of the substrate. Forming a concave cavity on the back surface of the cap, the bottom surface of the cavity and the back surface of the semiconductor chip are fixed with a first resin, and the electrodes on the main surface of the semiconductor chip and the internal bumps are solder-connected. The main surface of the semiconductor chip and the substrate are fixed with a second resin, and the peripheral edge of the cavity of the cap and the substrate are fixed with a third resin.

In the semiconductor device having the first or second structure, particularly, the first, second, and third resins are common thermoplastic resins, and the cap material is copper or aluminum. Alternatively, it is also characterized in that glass epoxy resin is used.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the sectional view of FIG. 1 showing a first embodiment of the present invention, the structure of a glass epoxy substrate 1 of this embodiment has a concave shape which is to be a chip mounting portion 2 substantially at the center of the back surface of the substrate. A cavity is provided, and a large number of solder bumps 4 for connecting to another circuit board 1 are provided around the cavity. Instead of the solder bumps 4, lead pins 5 of FIG. 3 described later may be provided. On the bottom surface of the cavity of the mounting portion 2 of the semiconductor chip 8 of the LSI, internal solder bumps 3 facing the electrodes of the chip 8 are provided. The internal bumps 3 of the cavity have a wiring pattern inside the substrate 1 so as to be electrically connected to the solder bumps 4 on the back surface of the substrate 1, and are led out to the external bumps 4 through the holes. .

As the cap 7, a glass epoxy substrate which is the same material as the substrate 1 is used. As the thermoplastic resin adhesive 9, a product name "Stix" is adhered to the upper surface of the cap 7. The same sheet-shaped adhesive 9 is adhered to the inner surface of the main surface of the chip 8 excluding the peripheral electrodes.
Also, the same adhesive is applied around the cap 7. In the next step, after the solder bumps 3 of the glass epoxy substrate 1 and the electrodes of the semiconductor chip 8 are aligned by the flip chip bonder, the solder is heated and melted in a nitrogen atmosphere, and the adhesive 9 is all softened. Let it adhere. By this operation, the electrodes of the chip 8 and the bumps 3 of the substrate 1 are connected, the surface of the substrate 1 and the chip 8 are bonded with a heat conductive adhesive, and the periphery of the cap 7 is sealed with the inner surface of the cavity of the substrate 1. Has been done. The chip connection portion of the glass epoxy substrate 1 is provided with a large number of heat radiation vias 11. The heat radiation via 11 is a drill hole of 0.2 to 0.3 mmφ plated with Cu.

First, 75 to 12 are formed on the entire surface of the heat dissipation via.
A sheet-shaped heat conductive thermoplastic resin adhesive 9 having a thickness of 5 μm, which is made of a plastic resin having a good thermal conductivity, is temporarily adhered, and then the chip 8 is adhered. Temporarily adhere. The periphery of the circuit board 3 and the periphery of the cap 7 are heat-bonded while positioning as described above so that the cap 7 is covered from the back surface of the semiconductor chip 8. The resin 9 in the gap between the chip 8 and the substrate 1 reduces the stress generated during the temperature cycle by half. Thus, the semiconductor device of the first embodiment is completed. The cap 7 is adhered to the back surface of the chip 8 and the periphery of the cap 7 with the same adhesive material to keep airtightness and contributes to alleviation of thermal stress in the bump connecting portion. The electrode layout of the semiconductor chip is a single row arranged in four sides or a plurality of staggered rows.

Referring to the cross-sectional view of FIG. 2 showing a second embodiment of the present invention, this embodiment will only describe the differences from the first embodiment described above. In the cavity of the glass epoxy substrate 1 of this embodiment, a heat radiating metal 12 is used instead of the heat radiating via 11, and is attached through the substrate 1. Further, the cap 7 is also preferably made of a material having a thermal expansion coefficient the same as or very close to that of the heat dissipation metal 12. For example, this material may be copper (coefficient of thermal expansion 160 to 170 × 1).
0 ^-7 , thermal conductivity 403 W / M / K, or aluminum (coefficient of thermal expansion 203 × 10 ^-7 , thermal conductivity 236 W / M)
/ K) is preferred. Also in this material combination, the manufacturing method is the same as that of the first embodiment.

Since the heat dissipation of this structure is distributed to the heat dissipation metal 12 side and the rear surface side of the semiconductor chip 8, extremely low heat resistance is possible and a high output power transistor can be used. For example, assuming that an external heat sink (not shown) of a sufficient size is attached, 1-2 ° C./W
It is also possible to realize a package with low thermal resistance. Further, since there is no breakage due to the thermal stress at the connection portion of the solder bump 3 and the thermal expansion coefficient of the heat radiating metal 12 and the cap 7 are close to each other, expansion due to heating / contraction causes similar expansion / contraction on both sides. As a result, the shearing stress of the solder bump 3 can be minimized.

The third embodiment of the present invention has the same structure and manufacturing method as FIG. 2 shown in the above-mentioned second embodiment, but is different from the second embodiment in that the cap is different. It means that a glass epoxy substrate is used as the material of 7. The destruction of the solder bumps 3 due to the thermal stress has an effect of minimizing the stress according to the same principle as in the first and second embodiments.

Although the fourth embodiment of the present invention is common to the structure and manufacturing method of the first embodiment, the material of the cap 7 of this embodiment is copper or aluminum instead of glass epoxy. . The glass epoxy substrate 1 etc. is the first
It is common with the embodiment of.

Referring to FIG. 3 showing a fifth embodiment of the present invention, in this embodiment, the semiconductor chip has a face-down structure, and the face-up structure of the first to fourth embodiments described above is used. It's different.

Although the lead pin 5 is used in this embodiment, it may be a spherical or hemispherical bump as shown in FIG. A concave cavity is formed substantially in the center of the cap 6, and the resin common to the resin 9 of the first embodiment is used between the back surface of the semiconductor chip 8 and the cavity and between the main surface of the semiconductor chip 8 and the substrate 1. Used between.

The cap 6 has the same dimensions as the rectangular plane of the substrate 1, and a metal such as copper or aluminum is used as this material to improve heat dissipation. This cap 6
May be a glass epoxy resin. The material of the substrate 1 and the like is the same as that of the first embodiment described above.

As described above, according to each embodiment of the present invention,
The semiconductor chip 8 is sandwiched by the same material from both sides, and the chip 8 follows the substrate 1 with respect to thermal expansion / contraction of the temperature cycle, which contributes to alleviation of stress at the bump connection portion. Further, since the heat is directly transmitted from the heat generating portion to the substrate and the cap, the heat resistance is low and the heat radiation effect is high. Further, since the thermoplastic resin 9 used has a lower moisture permeability than the epoxy resin, the moisture resistance is improved. Further, the repairability is remarkably improved because it can be easily peeled off by peeling the repairability slightly higher than the bonding work temperature.

[0036]

As described above, according to the present invention,
When bump-bonding a material whose coefficient of expansion is significantly different from that of the semiconductor chip, the effect of preventing damage to the bump connection part due to the difference in thermal expansion, and efficient heat dissipation from the semiconductor chip with a large heat generation, low thermal resistance and high reliability The effect of supplying the semiconductor device described above is obtained, bumps are not broken when mounted on a substrate as a bare chip, temperature cycle resistance is improved, heat dissipation from the chip surface is also improved, and moisture resistance of 10 ° C / W or less is achieved. The properties are also improved, and the effects such as having moisture resistance close to that of a ceramic package are obtained, and the above-mentioned respective problems are all achieved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a semiconductor device according to first and fourth embodiments of the present invention.

FIG. 2 is a sectional view showing a semiconductor device of second and third embodiments of the present invention.

FIG. 3 is a sectional view showing a fifth embodiment of the present invention.

4A to 4E are cross-sectional views showing, in the order of steps, a method for manufacturing a conventional semiconductor device according to a first example.

5A to 5C are cross-sectional views showing, in the order of steps, a method for manufacturing a conventional semiconductor device according to a second example.

[Explanation of symbols]

 1 Wiring board 2 Chip mounting part 3,4,24 Solder bump 5 Lead pin 6,7 Cap 8,28 Semiconductor chip 9,29 Thermoplastic resin 11 Heat dissipation via 12 Heat dissipation metal 13 Hole 14 Protection sheet 15,16 Adhesive 19 Polymer insertion Agent 20 Bonding tool 22 Substrate electrode 21 Hot plate 23 Circuit board 26 Chip electrode 30 Composite paste

Claims (7)

[Claims] 1. A concave cavity is formed on the back surface of an insulating substrate, an external bump or an external lead pin is formed on the back surface around the cavity, and the bottom surface of the cavity and the main surface of the semiconductor chip are first. An internal bump, which is fixed by a resin, is electrically connected to the external bump or the external lead pin and is formed on the bottom surface of the cavity and the electrode of the semiconductor chip is soldered, and the back surface of the semiconductor chip and the cap are 2. A semiconductor device characterized in that it is fixed with a second resin, and the cap and the cavity are fixed with a third resin. 2. The semiconductor device according to claim 1, wherein a bottom surface of the cavity is a heat dissipation metal. 3. The semiconductor device according to claim 1, wherein the heat dissipation metal and the cap are made of the same material. 4. The semiconductor device according to claim 1, wherein a large number of heat dissipation vias are formed on the bottom surface of the cavity. 5. An internal bump is formed on the main surface of an insulating substrate, an external bump or an external lead pin electrically connected to the internal bump is formed on the back surface of the substrate, and a concave cavity is formed on the back surface of the cap. The bottom surface of the cavity and the back surface of the semiconductor chip are fixed by a first resin, the electrodes on the main surface of the semiconductor chip and the internal bumps are solder-connected, and the main surface of the semiconductor chip and the substrate are formed. Are fixed by a second resin, and the peripheral edge of the cavity of the cap and the substrate are fixed by a third resin. 6. The semiconductor device according to claim 1, wherein the first, second and third resins are common thermoplastic resins. 7. The semiconductor device according to claim 1, wherein copper, aluminum, or glass epoxy resin is used as a material of the cap.