JP2001284387A - Semiconductor device and method of manufacture, and mounting structure of the semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection which causes no defective conduction, e.g. short circuit or open circuit, or unstable connection stably and inexpensively, even if the area is limited due to high density and fine pitch of transparent electrode pads on a glass substrate and bump electrodes on a semiconductor chip. SOLUTION: The semiconductor device comprises I/O terminals, i.e., electrode pads 16 provided on a semiconductor substrate 2, an insulation film 6 provided on the semiconductor substrate 2 to expose the electrode pads 16, lower electrodes having at least aluminum provided on the electrode pads 16, and bump electrodes 4 provided on the lower electrodes where acicular bumps 42 are provided on the surface of the lower electrodes and protrusions and recesses corresponding to the acicular bumps 42 on the surface of the lower electrodes are provided on the top of the bump electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a face-down bonding technique for a semiconductor chip in which a semiconductor element forming surface is mounted downward, and a structure of a protruding electrode on the semiconductor chip for electrical and mechanical connection. And a manufacturing method thereof and a semiconductor device mounting structure by face-down bonding.

[0002]

2. Description of the Related Art In recent years, the pitch between electrodes has become extremely small with the increase in the density of semiconductor chips, and the mounting connection area between a circuit board and a semiconductor chip, that is, the electrode area at the time of connection, has become narrow. is there.

As a representative example, a mounting structure of a COG (chip-on-glass) mounting method will be described with reference to FIG.

Hereinafter, a manufacturing method will be described with reference to FIGS.

[0005] A chip-on-glass (hereinafter referred to as COG) is a conventional technique in which a peripheral portion of a glass substrate constituting a liquid crystal display device is extended and a plurality of semiconductor chips for driving the liquid crystal display device are mounted in the extended region. ) There is paste mounting.

As shown in FIG. 10, two glass substrates 2
The liquid crystal 48 is sealed in the gap between the four, and the glass substrate 2 of the liquid crystal display device 38 is formed by a sealing material 54 formed by a printing method.
At the same time, a pixel pattern is formed by a transparent electrode 46 made of indium tin oxide (hereinafter referred to as ITO) or the like formed on the substrate 4 by using a vacuum deposition method or a sputtering method. A transparent electrode 46 of ITO or the like is routed in the region thus formed, and a plurality of semiconductor chips 8 for driving the liquid crystal display device 38 are mounted on the wiring.

FIG. 10 is a cross-sectional view showing a state where a semiconductor chip is mounted on a liquid crystal display device.

Semiconductor chip 8 having protruding electrodes 4 made of copper (Cu) or gold (Au) having a height of 5 μm to 50 μm.
And a transparent electrode 4 formed of ITO on a glass substrate 24.
The six pads are mechanically and electrically connected with a conductive adhesive 44.

Then, the semiconductor chip 8 and the glass substrate 24
Is filled with a sealing resin.

The input-side transparent electrode wiring on the liquid crystal display device 38 is further electrically and mechanically connected to the wiring of the flexible substrate 32 (hereinafter, referred to as FPC) via an anisotropic conductive film 36 for FPC. I have.

Next, a manufacturing method for forming the above-described structure in the prior art will be described with reference to the drawings.

As shown in FIG. 11, except for the aluminum wiring 12, the semiconductor substrate 2 is covered with an insulating film 6 such as a silicon nitride film (SiN) and is electrically insulated from the outside.

A common electrode film 14, which is also a barrier metal layer for preventing metal diffusion and serves as an electrode for electrolytic plating, is formed on the aluminum wiring 12 of the semiconductor substrate 2 by using a vacuum evaporation method or a sputtering method.

Next, as shown in FIG.
6 is formed, and a necessary portion above the aluminum wiring 12 is selectively opened in order to perform electrolytic plating on a portion where a protruding electrode is to be selectively formed.

Thereafter, as shown in FIG. 13, copper (Cu) is formed on the common electrode film 14 by an electrolytic plating method.
The mushroom-shaped protruding electrode 4 is formed by forming gold (Au) using an electrolytic plating method.

Thereafter, as shown in FIG.
6 is removed, and as shown in FIG. 15, the common electrode film other than the protruding electrodes is removed with an etchant.

Finally, the semiconductor substrate 2 is cut into single semiconductor chips 8 by cutting (hereinafter referred to as dicing) the boundary between adjacent semiconductor chips in the semiconductor substrate 2.

Next, as shown in FIG. 16, an epoxy-based material in which conductive particles such as silver (Ag) or an alloy film of silver (Ag) and palladium (Pd) are mixed into the bump electrodes 4 on the semiconductor chip 8. As shown in FIG. 17, the conductive adhesive 44 is applied to the semiconductor chip 8 and the projecting electrode 4 formed on the glass substrate 24 after applying the conductive adhesive 44 to the projecting electrode 4 as shown in FIG. After the alignment of the corresponding transparent electrodes 46, face-down bonding mounting is performed as shown in FIG. 18, heat curing is performed, and electrical and mechanical connections are made.

Since the conductive adhesive 44 is usually an epoxy-based adhesive, it is hardened at about 80 ° C. to 120 ° C., so that the transparent electrode 46 on the glass substrate 24 and the projections on the semiconductor chip 8 are hardened. The electrodes 4 are bonded and electrically and mechanically connected.

Finally, as shown in FIG. 19, the gap between the semiconductor chip 8 and the glass substrate 24 is filled with a sealing resin 22 and cured to further improve the reliability.

On the transparent electrode 46 on the glass substrate 24 formed on the right side in FIG. 10, an FPC anisotropic conductive film 36 containing conductive particles is interposed.
The PC board 32 is arranged, and pressure is applied to the FPC board 32 in a heated state to perform thermocompression bonding.

The FPC board 32 is a film in which copper (Cu) wiring electrodes are patterned on a polyimide sheet in order to supply power to the semiconductor chip 8 and to provide an input signal. The connection pitch is about 80 to 100 μm. is there.

[0023]

In the prior art, the pitch between the electrodes which can be stably connected is about 150 μm, and when the pitch between the electrodes becomes narrower than this, the conductive adhesive is applied to the protruding electrodes on the semiconductor chip. A transfer sagging phenomenon occurs during transfer, and a short circuit between adjacent electrodes occurs.

Further, due to the variation in the transfer of the conductive adhesive, a number of places where the conductive adhesive is not transferred to the protruding electrodes on the semiconductor chip occur, resulting in an open defect.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems and to reduce the pitch and pitch of the transparent electrode pads on the glass substrate and the bump electrodes on the semiconductor chip.
An object of the present invention is to provide a semiconductor device, a method of manufacturing the semiconductor device, and a mounting structure of the semiconductor device, which can supply a connection without a conduction failure such as a short circuit or an open circuit or a conduction instability even when the area is reduced, stably and inexpensively.

[0026]

Means for Solving the Problems In order to achieve the above object, the following means are adopted for a semiconductor device, a method of manufacturing the same and a mounting structure of the semiconductor device according to the present invention.

A semiconductor device according to the present invention comprises an electrode pad as an input / output terminal provided on a semiconductor substrate, an insulating film provided on the semiconductor substrate so that the electrode pad is exposed, and an aluminum film provided on the electrode pad. And a protruding electrode provided on the lower electrode, having a needle-like projection on the surface of the lower electrode, and having irregularities on the top of the projection electrode corresponding to the needle-like projections on the surface of the lower electrode. It is characterized by having.

In the method of manufacturing a semiconductor device according to the present invention, a step of forming an insulating film on a semiconductor substrate having a pad electrode formed thereon and selectively opening the insulating film to expose the pad electrode; A step of forming a common electrode film having aluminum, a step of performing a temperature cycle of high and low temperatures to form needle-like projections on the surface of the common electrode film, forming a plating resist on the entire surface, and forming a pad by photolithography. Forming an opening on the electrode region, forming a protruding electrode in the opening of the plating resist by plating, and etching the common electrode film so as to leave a protruding electrode film in a region matching the protruding electrode. And forming a semiconductor chip by dicing the semiconductor substrate.

The mounting structure of the semiconductor device according to the present invention comprises an electrode pad which is an input / output terminal provided on a semiconductor substrate, an insulating film provided on the semiconductor substrate so as to expose the electrode pad, and an electrode film provided on the electrode pad. A lower electrode having at least aluminum, and a protruding electrode provided on the lower electrode, having a needle-like projection on the surface of the lower electrode, and corresponding to the needle-like projection on the surface of the lower electrode, on the top of the protruding electrode. Is characterized by having a sealing resin provided between the semiconductor chip and the circuit board, connecting the semiconductor chip having the unevenness, the circuit board having the wiring pattern, and the projection electrode having the unevenness on the top and the wiring pattern. .

[Operation] When forming a projection electrode on a semiconductor substrate, when forming a common electrode film, needle-like projections are formed on an aluminum (Al) film which is a first projection electrode film of the common electrode film. By doing so, a large number of minute projections are formed on the common electrode film.

Thereafter, a protruding electrode is formed in a plating step. At this time, plating isotropically grows on needle-like protrusions formed on the surface of the common electrode film on the bump surfaces, and the bumps are formed on the protruding electrodes. Small protrusions are formed.

The surface of the protruding electrode formed on the semiconductor substrate is not flat, but is made uneven in the semiconductor device of the present invention, and the connection between the electrode pad on the circuit board and the protruding electrode formed on the semiconductor chip is made in surface contact. Change from mounting to point contact mounting.

The mechanical bonding between the circuit board and the semiconductor chip is performed by thermocompression bonding via a thermosetting resin such as an epoxy resin.

According to the structure and the manufacturing method of a semiconductor device of the present invention, a large number of fine projections are selectively formed on a projection electrode formed on a semiconductor substrate, and the surface of the projection electrode is in a state where a large number of fine irregularities are formed. .

In this way, a large number of connection points for promoting the point connection between the electrode pads formed on the circuit board and the protruding electrodes are intentionally produced, so that the semiconductor device of the present invention has a small pitch and a small area. Connection of the integrated semiconductor device can be stabilized.

Further, by forming a large number of fine projections on the projection electrodes, the surface area at the time of thermocompression bonding can be increased, and the mechanical adhesive strength at the place connected by a thermosetting resin such as epoxy increases.

Since an anisotropic conductive film in which conductive particles are mixed in a thermosetting resin is not used, a simple and inexpensive industrially excellent semiconductor structure and a method for manufacturing the same can be provided.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[Structural Description of Semiconductor Device: FIG. 1] As shown in FIG. 1, the structure of a bump electrode formed on a semiconductor substrate according to the present invention will be described.

A common electrode film 14 made of a laminated film of aluminum (Al), chromium (Cr), and copper (Cu) is provided on the aluminum electrode 12 of the semiconductor substrate 2, and copper (Cu) is provided on the common electrode film 14. ) And gold (Au).

The bump electrode made of copper (Cu) and gold (Au) has a large number of bumps 18 formed on the top of the bump electrode, and the surface of the bump electrode 4 has a large number of irregularities. It is a feature of.

The mounting structure of the semiconductor device according to the present invention is as follows.
A semiconductor chip having a projecting electrode 4 made of gold (Au) having a height of 15 μm and an electrode pad 16 formed on a circuit board 10 are mechanically and electrically connected with a thermosetting resin 30 such as an epoxy resin.

The thermosetting resin 30 such as the epoxy resin
Has a structure that also serves to seal the gap between the semiconductor chip 8 and the circuit board 10.

[Description of Method for Manufacturing Semiconductor Device: FIGS. 1 to 6] Next, a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described. In the description of this embodiment,
A method for manufacturing a semiconductor device will be described using COG mounting as an example.

As shown in FIG. 2, on the semiconductor substrate 2, an insulating film 6 having an opening of the aluminum wiring 12 of the semiconductor substrate 2 is formed.
Covered with.

On the aluminum wiring 12 of the semiconductor substrate 2, a common electrode film 14 for forming a common electrode at the time of electrolytic plating is formed. The common electrode film 14 is formed on the entire surface of the semiconductor substrate 2 by a vacuum evaporation method or a sputtering method.

The common electrode film 14 is formed by sequentially forming aluminum (Al) with a thickness of 0.8 μm, chromium (Cr) with a thickness of 0.01 μm, and copper (Cu) with a thickness of 0.8 μm from the semiconductor substrate 2 side.

As shown in FIG. 2, after forming the common electrode film of aluminum (Al) which is the first film of the common electrode, that is, before forming chromium (Cr) and copper (Cu), about 4 μm. Are formed on the surface of the aluminum (Al) film.

The needle-like projection is a projection similar to a stab protruding from the surface of the aluminum (Al) thin film. The needle-like projections are generally formed at the time of forming an aluminum (Al) thin film or aluminum (Al) such as aluminum (Al) sinter.
It occurs during a temperature cycle applied to the semiconductor substrate 2 after the formation of the thin film.

Due to the difference in the thermal expansion coefficient between the semiconductor substrate 2 and the aluminum (Al), the aluminum (Al) is subjected to a temperature cycle from room temperature to about 400 ° C. and further to about two cycles of cooling to form needle-like projections. Needle-like projections are formed on the entire surface of the semiconductor substrate 2.

The needle-like projections on the aluminum (Al) thin film grow according to the magnitude of the compression pressure. The main cause of the compression pressure is that the semiconductor substrate 2 and the aluminum (Al)
This is the difference between the thermal expansion coefficients of the thin films.

The coefficient of thermal expansion of aluminum (Al) is 2
3.5 × 10 ⁻⁶ ° C. ⁻¹ , but the semiconductor substrate 2
× 10 ^-6 ° C ^-1 .

Therefore, when a temperature cycle such as heating and cooling is applied to the semiconductor substrate 2 on which the aluminum (Al) thin film is formed, the aluminum (Al) thin film thereon becomes 1
Try to expand and contract 0 times.

As a result, a compressive pressure is generated, causing the growth of needle-like projections. That is, as shown in FIG. 2, a large number of needle-like minute projections can be formed on the semiconductor substrate 2.

Next, a chromium (Cr) film and a copper (Cu) film are sequentially formed on the aluminum (Al) on which the acicular projections are formed.

Thereafter, as shown in FIG.
A photosensitive resin (photoresist) 6 having a thickness of 17 μm is formed on the entire surface of the common electrode film 14 by a spin coating method.

Further, the photosensitive resin is exposed using a predetermined photomask by an exposure device, and thereafter, the photosensitive resin is patterned by a photolithography process of performing a developing process.

By this patterning, the photosensitive resin forms an opening in a region where the bump electrode 4 is to be formed later, exposing the common electrode film 14.

At this time, the needle-like protrusions 42 other than the openings for forming the protrusion electrodes 4 are covered with the thick resist film, so that plating may be performed on the portions other than the openings for forming the protrusion electrodes. There is no.

Next, as shown in FIG.
4 is used as a plating electrode, and a protruding electrode 4 having a thickness of 10 μm to 15 μm in a straight wall shape is formed on the common electrode film 14 in the opening of the photosensitive resin by gold plating.

At this time, the plating grows isotropically with the needle-like projections 42 formed on the common electrode film 14 as nuclei, so that the uppermost surface of the projection electrodes is not flat but the needle-like projections are nuclei. Many bump-like minute projections 18 are formed.

Thereafter, as shown in FIG. 5, the photosensitive resin, which is a resist film, is removed, and the common electrode film is etched by wet etching using the bump electrodes 4 as an etching mask, as shown in FIG. Then, a lower electrode is formed in a region corresponding to the protruding electrode.

Lastly, the semiconductor substrate 2 is cut into single semiconductor chips 8 by cutting the boundary between adjacent semiconductor chips 8 in the semiconductor substrate 2 (hereinafter referred to as dicing).

The reason why wet etching is performed when forming the lower electrode by etching the common electrode film described with reference to FIG. 6 is as follows.

The common electrode film 14 has a three-layer structure of 0.8 μm of aluminum, 0.01 μm of chromium, and 0.8 μm of copper from the semiconductor substrate 2 side, and is formed as described above. This is because in the dry etching method, an etching gas used to obtain an etching selectivity between a layer to be etched and another layer must be used, so that the selection of the composite etching gas becomes complicated.

In addition, the dry etching method takes a very long time to perform the etching process, which is disadvantageous in industrial production, and the equipment used for the etching process is expensive. This is because there is also a problem that it is lost.

However, according to the wet etching method, by selecting an etching solution having an etching selectivity, an etching process can be easily performed without requiring a large-scale facility.

[Description of Mounting Structure of Semiconductor Device: FIGS. 7 to 9] Next, an embodiment of a mounting structure of a semiconductor device according to the present invention will be described with reference to the drawings.

The semiconductor chip 8 formed by the above-described manufacturing method is connected to a glass substrate 24 which is a circuit substrate of a liquid crystal display panel. A liquid crystal display panel will be described as an example of the mounting structure with reference to FIGS.

As shown in FIG. 7, in order to mount the semiconductor chip 8 on the glass substrate 24, the semiconductor chip 8 is face-down with the surface on which the semiconductor element is formed facing downward, and the projecting electrode 4 formed on the semiconductor chip 8 is turned down. And the transparent electrode 46 formed on the glass substrate 24 are aligned.

As shown in FIG. 8, an epoxy or the like is provided between the semiconductor chip 8 and the protruding electrode 4 formed on the semiconductor chip 8 and the glass substrate 24 and the transparent electrode 46 formed on the glass substrate 24. The thermosetting resin 30 is interposed.

Further, as shown in FIG. 9, in a state where the semiconductor chip 8 is set on the glass substrate 24, the semiconductor chip 8 is subjected to a heat treatment while being pressed against the glass substrate 24, so that the protruding electrodes on the semiconductor chip are formed. 4 and glass substrate 2
4 and the transparent electrode 46 are mechanically and electrically connected.

According to the mounting structure of the semiconductor device of the present invention, ultra-fine connection with a connection pitch of 40 μm or less and a connection area of 2000 μm ² or less with respect to the connection area above the protruding electrodes is also possible.

[0074]

As described above, according to the semiconductor device mounting structure and the method of manufacturing the same of the present invention, when the transparent electrode pad on the glass substrate and the protruding electrode on the semiconductor chip are face-down connected, A minute projection formed on a projection electrode formed on a semiconductor chip makes a large number of point connections, so that a finer connection pitch can be achieved and a lower connection resistance can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state where a semiconductor chip and a circuit board according to an embodiment of the present invention are connected.

FIG. 2 is a cross-sectional view showing a state in which a common electrode film and needle-like protrusions are formed on a semiconductor substrate according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a state in which a thick resist film is formed on a semiconductor substrate according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a state in which gold (Au) plating is performed on a semiconductor substrate to form a protruding electrode in the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a completed state of a straight protruding electrode on which fine protrusions of gold (Au) have been formed after removing a resist on a semiconductor substrate according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a completed state of a straight protruding electrode on which fine protrusions of gold (Au) are formed after removing a common electrode film on a semiconductor substrate according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a state in which the semiconductor chip and the glass substrate are aligned in the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a state in which a thermosetting resin such as an epoxy resin is applied on the glass substrate after the alignment of the semiconductor chip and the glass substrate in the embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a state in which the semiconductor chip and the glass substrate are thermocompression-bonded in the embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a state where a semiconductor chip is mounted by COG paste mounting of a liquid crystal display device according to a conventional technique.

FIG. 11 is a cross-sectional view showing a state in which a common electrode film is formed on a semiconductor substrate in a conventional technique.

FIG. 12 is a cross-sectional view showing a state in which a resist film is formed on a semiconductor substrate in a conventional technique.

FIG. 13 is a cross-sectional view showing a state where bumps are formed by performing electroplating on a semiconductor substrate according to a conventional technique.

FIG. 14 is a cross-sectional view showing a state in which a resist film on a semiconductor substrate is removed in a conventional technique.

FIG. 15 is a cross-sectional view showing a state in which a common electrode film on a semiconductor substrate is removed in a conventional technique.

FIG. 16 is a cross-sectional view showing a state in which a conductive adhesive is transferred onto a protruding electrode on a semiconductor chip in a conventional technique.

FIG. 17 is a cross-sectional view showing a state in which a semiconductor chip and a glass substrate are aligned in a conventional technique.

FIG. 18 is a cross-sectional view showing a state in which a semiconductor chip and a glass substrate are bonded in a conventional technique.

FIG. 19 is a cross-sectional view showing a state in which a semiconductor chip and a glass substrate are sealed in a conventional technique.

[Explanation of symbols]

2: Semiconductor substrate 4: Protruding electrode
6: Insulating film 8: Semiconductor chip 10: Circuit board 12: Aluminum wiring 14: Common electrode film 16: Electrode pad 18: Hump-shaped minute protrusion 22: Sealing resin 24: Glass substrate 26: Resist film 28: Liquid crystal display device 30: thermosetting resin such as epoxy 32:
FPC board 36: Anisotropic conductive film for FPC 38: Liquid crystal display device 42: Needle-like projection 44: Conductive adhesive 46: Transparent electrode 48: Liquid crystal 54: Seal material

Claims (5)

[Claims] 1. An electrode pad which is an input / output terminal provided on a semiconductor substrate, an insulating film provided on the semiconductor substrate so as to expose the electrode pad, and a lower electrode provided on the electrode pad and containing at least aluminum. A projection electrode provided on the lower electrode, having a needle-like projection on the surface of the lower electrode, and having irregularities on the top of the projection electrode corresponding to the needle-like projection on the surface of the lower electrode. Semiconductor device. 2. The semiconductor device according to claim 1, wherein the lower electrode is a laminated film of aluminum, chromium, and copper from the semiconductor substrate side. 3. The semiconductor device according to claim 1, wherein the cross-sectional shape of the protruding electrode is mushroom or straight wall. 4. A step of forming an insulating film on a semiconductor substrate on which a pad electrode is formed, selectively opening the insulating film to expose the pad electrode, and forming a common electrode film having at least aluminum on the entire surface. Forming a needle-like protrusion on the surface of the common electrode film by performing a temperature cycle of high and low temperatures; forming a plating resist on the entire surface; and forming an opening on the pad electrode region by photolithography. Forming a protruding electrode in the opening of the plating resist by plating; and etching the common electrode film so as to leave a protruding electrode film in a region matching the protruding electrode, thereby forming a lower electrode. Dicing the semiconductor substrate to form a semiconductor chip. 5. An electrode pad which is an input / output terminal provided on a semiconductor substrate, an insulating film provided on the semiconductor substrate so as to expose the electrode pad, and a lower electrode provided on the electrode pad and containing at least aluminum. A protruding electrode provided on the lower electrode, a semiconductor chip having an acicular projection on the lower electrode surface, and having an irregularity on the top of the protruding electrode corresponding to the acicular projection on the lower electrode surface; A mounting structure for a semiconductor device, comprising: a circuit board having a wiring pattern; and a sealing resin provided between the semiconductor chip and the circuit board, for connecting a protruding electrode having irregularities on the top and the wiring pattern.