JPH0443418B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a film carrier used for mounting semiconductor devices, and particularly to bonding between a semiconductor device and a film carrier.

(Conventional structure and its problems) In general, among bonding methods for semiconductor devices, film carriers, which can bond multiple electrodes at once, are fast, mass-producible, and highly reliable. The method is widely known.

This film carrier consists of a flexible insulating film 1 in which device holes are formed as shown in FIG.
On top, a plurality of leads 2 formed to extend into the device hole are bonded with an adhesive 3, and gold bumps 6 formed on an aluminum pad 5 of a semiconductor element 4 and a film carrier are bonded together. The tips of the leads 2 are bonded to each other by thermocompression bonding or ultrasonic bonding.

However, in such a conventional film carrier, since the semiconductor element 4 requires a bump forming process, the yield of the semiconductor element itself is greatly reduced. This is because even if bumps are formed on a good semiconductor device, it may turn out to be a defective product when the bumps are formed, and the semiconductor device on which the bumps are formed becomes very expensive. Further, there were drawbacks such as having to newly request each semiconductor manufacturer for bump formation processing and not being able to freely use the products of each semiconductor manufacturer.

Conventionally, as shown in FIG. 3, gold bumps 7 are formed on the tips of leads 2 extending into device holes of flexible insulating film 1 by gold plating or thermocompression bonding of gold balls. forming a semiconductor element 4
A bumped film carrier has been proposed which allows bonding of aluminum pads 5 without treatment.

However, in conventional bumped film carriers, the bumps are made only of gold, so during thermocompression bonding and ultrasonic bonding, the gold bumps 7
The collapse of the gold bumps was large, and a short circuit occurred between the gold bumps 7, making it impossible to follow the increase in fine pitch. Therefore, it cannot be used in highly integrated semiconductor devices, and its applications are limited.
Because gold bump 7 is severely crushed, lead 2
There were drawbacks such as sinking into the gold bumps 7 and short-circuiting the edges of the semiconductor element 4 and the leads 2.

(Object of the Invention) The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and is capable of bonding a semiconductor element without being processed, has small bump collapse, and is suitable for fine patterning. The present invention provides a bumped film carrier that is easy to manufacture and has excellent mass productivity, and a method for manufacturing the same.

(Structure of the Invention) In order to achieve the above object, the present invention provides tips of a plurality of leads formed on a flexible insulating film or extending to an opening formed in the flexible insulating film. It is equipped with a bump made of a layer of metal harder than gold at the center and a gold layer on both sides or the entire surface.A window is provided on an inorganic plate with gold vapor-deposited on the main surface using photoresist. A bump is formed by successively laminating gold, a metal harder than gold, and gold on this window portion, and this bump is thermocompression bonded to the lead of the film carrier.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 is a diagram showing the structure of an embodiment of the bumped film carrier of the present invention, and the same reference numerals as in FIGS. 1 and 2 indicate the same parts. In FIG. 3, bumps 8 are formed at the tip portions of a plurality of leads 2 formed to extend to the device hole of the flexible insulating film 1. As shown in FIG. This bump 8 has a metal layer 8a having a thickness of 5 μm to 30 μm formed on both sides or the entire surface of a metal layer 8a made of copper, nickel, or palladium and having a thickness of 5 μm or more and which is harder than gold.

In the above structure, the present embodiment has a structure in which the bump 8 is not only made of gold but also has a layer 8a of a metal harder than gold sandwiched between two gold layers 8b. 4 by thermocompression bonding or ultrasonic bonding, the metal layer 8a, which is harder than gold, can minimize crushing of the bumps 8 and prevent short circuits between the bumps 8. It is possible to prevent the leads 2 from sinking into the edges of the semiconductor element 4, thereby preventing the leads 2 from coming into contact with the edge portions of the semiconductor element 4. At this time, the metal layer 8a, which is harder than gold, needs to have a thickness of 5 μm or more, and if it is less than that, the strength will be insufficient and it will not be possible to prevent the bumps 8 from collapsing. Furthermore, the semiconductor element 4 is bonded to the aluminum pad 5 by deforming the gold layer 8b on the tip side of the bump 8, thereby breaking the naturally occurring aluminum oxide film on the aluminum pad 5 and exposing the base aluminum surface. Sufficient bonding strength can be obtained because eutectic bonding occurs through heat and pressure.
At this time, the gold layer 8b on the tip side of the bump 8 has a thickness of 5 μm to
Requires a thickness of 30μm, below which gold layer 8b
Since the deformation is small, the semiconductor element 4 cannot be reliably bonded to the aluminum pad 5, and if the deformation is more than that, the gold layer 8b will be severely crushed, and there is a risk that a short circuit between the bumps 8 will occur. Furthermore, by providing the layer 8a of a metal harder than gold, the amount of gold used for the bumps 8 can be reduced to 1/2 to 1/3 of the conventional amount, thereby reducing costs.

Further, this example is manufactured according to the steps shown in FIG. In FIG. 4, the same reference numerals as in FIG. 3 indicate the same components. First, gold is deposited on the main surface of an inorganic plate 9 with a smooth surface to form a gold deposited film 1.
0 to form a common electrode for electroplating, a window 12 is formed using photoresist 11 at the same position as the pad position of the semiconductor element. Then, in the window 12, a gold layer 8b with a thickness of 5 μm to 30 μm, a layer 8a of a metal harder than gold made of copper, nickel, or palladium with a thickness of 5 μm or more, and a
Gold layers 8b each having a thickness of 5 μm to 30 μm are sequentially laminated by electroplating to form a bump 8 consisting of three layers: a gold layer 8b, a layer 8a of a metal harder than gold, and a gold layer 8b. Next, after aligning the tip portions of the leads 2 of the film carrier with the bumps 8, the leads 2 and the gold layer 8b located on the upper surface of the bumps 8 are bonded by thermocompression using the heating tool 13. Thereafter, the bumps 8 are separated from the inorganic plate 9 to complete the bumped film carrier.

In the above manufacturing method, the bump 8 of this example
can be formed simply by sequentially laminating layers using the electroplating method, and furthermore, since the bumps 8 are peeled off at the interface between the gold vapor deposited film 10 and the electroplated gold layer 8b, it is very easy to form a film carrier with bumps. In addition, the inorganic plate 9 can be used semi-permanently as a bump substrate because the gold vapor deposited film 10 and photoresist 11 remain, and if the same inorganic plate 9 is reused, it can be used for a second time. After that, the bumps 8 can be formed by performing only three plating steps: the gold layer 8b, the layer 8a of a metal harder than gold, and the gold layer 8b. Furthermore, when thermocompression bonding the leads 2 and bumps 8, only bump substrates on which good bumps are formed are selected and thermocompression bonded, thereby producing a film carrier with bumps of excellent quality. Can be done. Note that the gold layer 8b located on the top surface of the bump 8 formed on the inorganic plate 9 needs to have a thickness of 5 μm to 30 μm in order to securely bond with the lead 2, and if it is less than that, the bond with the lead 2 will not be possible. If the amount is more than that, the gold layer 8b will be greatly deformed when bonded to the lead 2, and there is a possibility that a short circuit between the bumps 8 may occur.

FIG. 5 is a diagram showing the structure of another embodiment of the bumped film carrier of the present invention, and the same reference numerals as in FIG. 3 indicate the same parts. This embodiment has a conical bump 8', and by making the bump 8' conical in this way,
When bonding to the semiconductor element 4, since the gold layer 8b at the tip of the bump 8' is sharp, the deformation can be further increased, so the oxide film on the surface of the aluminum pad 5 can be easily broken and the aluminum pad can be bonded to the underlying aluminum. It is also possible to lower the pressure conditions at that time.

Next, the manufacturing method of this example will be specifically explained. First, a polyimide film with a width of 35 mm and a thickness of 125 μm is used as the long flexible insulating film 1, and as shown in FIG. 6, sprocket holes 14 and device holes 15 are punched using a mold prepared in advance. It was formed by The sprocket holes 14 are 2 mm x 3 mm holes provided at 4.75 mm pitch on both ends of the flexible insulating film 1 in the width direction, and the device holes 15
A hole of 5 mm x 5 mm was provided in the center of the flexible insulating film 1 at a pitch of 3 frames of the sprocket hole 14, and an electrolytic copper film with a thickness of 35 μm, a width of 22.5 mm, and an adhesive 3 of 20 μm thick was provided. Place the foil into sprocket hole 14.
After laminating it on the flexible insulating film 1 while avoiding the problem, the leads 2 were formed in a pattern matching the pad positions of the semiconductor element 4 by photo-etching. In forming the lead 2, the device hole 1
In order to prevent etching of the back side of the copper foil from 5 onwards, an alkali-soluble resist was applied to the electrolytic copper foil from the back side of the device hole 15 and removed after pattern formation. Further, a ferric chloride solution was used as an etching solution. After that, the flexible insulating film 1 with the leads 2 formed thereon is immersed in a tin plating solution, and a tin film with a thickness of 0.4 μm to 0.6 μm is formed on the surface of the copper foil by an electroless plating method. I made a film carrier with lead 2 extending above it.

Next, bumps were made using the inorganic plate 9' shown in FIG. 7 in the same process as shown in FIG. First, a 4-inch wafer silicon plate is used as the inorganic plate 9', and a conical groove 16 with a depth of 25 μm is formed on the main surface at the same position as the pad position of the semiconductor element 4, as shown in FIG. Formed. Next, a gold vapor deposited film 10 with a thickness of 2000 to 2500 Å is formed on the main surface of the inorganic plate 9' by a vapor deposition method, and a photoresist 11 is further applied to the surface of the gold vapor deposited film 10 using a spinner, and heated at 90°C.
Bake for 10 minutes. After that, the mask is aligned with the conical grooves 16 of the inorganic plate 9' using a mask aligner, and the conical grooves 16 are exposed to ultraviolet rays and developed.
The upper photoresist 11 was removed to form a window 12, and further baked at 110° C. for 10 minutes. next,
A gold plating bath and a nickel plating bath are prepared. First, an inorganic plate 9' is immersed in the gold plating bath, and a gold layer 8b with a thickness of 10 μm is formed on the window 12 where there is no photoresist 11 by electroplating, and then washed with water. After that, it is immersed in a nickel bath and the thickness is electroplated.
A layer 8a of a metal harder than gold made of nickel with a thickness of 10 μm is formed on the gold layer 8b, and after further washing with water, the inorganic plate 9' is immersed in a gold plating bath again, and the gold layer 8b with a thickness of 10 μm is formed by electroplating. was formed on the nickel layer and washed with water to obtain bumps 8'.

After aligning the tip of the lead 2 of the film carrier and the bump 8' using a microscope,
Using a heating tool 13 made of molybdenum heated to about 300°C, the bumps are bonded by thermocompression bonding between the leads 2 and the bumps 8' by setting the pressure so that 30 to 50 g of pressure is applied to each lead. The attached film carrier has been completed.

Using this example manufactured as described above, a molybdenum tool with a tool tip temperature of 480°C to 500°C was applied directly to the aluminum pad 5 of the semiconductor element 4 with a pressure of 60 to 80 g per lead. Even when bonding was performed, there was no bump crushing in this example, and a reliable bonding state could be obtained.

(Effects of the Invention) As explained above, in the present invention, a bump formed by sequentially laminating gold, a metal harder than gold, and gold is bonded by thermocompression to the tip of a lead of a film carrier. The semiconductor device can be bonded to the semiconductor device pad without any processing,
At this time, reliable bonding can be obtained, the crushing of the bumps is small, and there is no contact between the edges of the semiconductor element and the leads, so it is suitable for fine patterning, and high quality products can be easily manufactured. It has advantages such as high productivity and high mass productivity.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional film carrier and a semiconductor device, FIG. 2 is a sectional view of a conventional bumped film carrier and a semiconductor device, and FIG. 3 is a sectional view of a conventional bumped film carrier and a semiconductor device. FIG. 4 is a process diagram of an embodiment of the method for manufacturing a film carrier with bumps according to the present invention;
FIG. 5 is a sectional view of another embodiment of the bumped film carrier of the present invention and a semiconductor element, and FIG. 6 is a plan view of the film carrier of another embodiment of the bumped film carrier of the present invention. , FIG. 7 is a sectional view of an inorganic plate used in manufacturing another embodiment of the bumped film carrier of the present invention. 1...Flexible insulating film, 2...Lead,
4...Semiconductor element, 5...Aluminum pad,
8... bump, 8a... layer of metal harder than gold,
8b...Gold layer, 9,9'...Inorganic plate, 10...
Gold vapor deposited film, 11... Photoresist, 12...
window, 13... heating tool, 15... device hole,
16...Conical groove.

Claims (1)

[Claims] 1. A plurality of leads formed on a flexible insulating film or extending to an opening formed in the flexible insulating film, and a plurality of leads formed at the tip portions of the leads. 1. A film carrier with bumps, characterized in that said bumps are formed by forming a gold layer on both sides or the entire surface of a layer of a metal harder than gold. 2. The bumped film carrier according to claim 1, wherein copper, nickel, or palladium is used as the metal harder than gold. 3. Claim 1, wherein the layer of metal harder than gold has a thickness of 5 μm or more.
Film carrier with bumps as described in section. 4. The bumped film carrier according to claim 1, wherein the gold layer has a thickness of 5 μm to 30 μm. 5. The film carrier with bumps according to claim 1, wherein the bumps are conical. 6 After depositing gold on the main surface of an inorganic plate with a smooth surface, a window is formed using photoresist at the same position as the pad of the semiconductor element, and gold, a metal harder than gold, and gold are sequentially laminated in this window area. a step of forming bumps by forming bumps on the flexible insulating film or on the tip portions of the plurality of leads extending to the openings formed in the flexible insulating film and on the inorganic plate; A method for producing a film carrier with bumps, which comprises the steps of aligning the formed bumps and then thermocompression bonding the bumps to the tips of the leads using a heating tool. 7. The method of manufacturing a bumped film carrier according to claim 6, wherein copper, nickel, or palladium is used as the metal harder than gold. 8. Claim 6, wherein the layer of metal harder than gold has a thickness of 5 μm or more.
A method for manufacturing a film carrier with bumps as described in . 9. Claim 6, wherein the gold layer of the bump has a thickness of 5 μm to 30 μm.
A method for manufacturing a film carrier with bumps as described in . 10. The method of manufacturing a bumped film carrier according to claim 6, wherein the inorganic plate has a conical groove at the same position as a pad of a semiconductor element.