JPH06252148A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a semiconductor device which has a low connection resistance and provides reliable connections in oxidation-prone wiring, such as aluminum wiring. CONSTITUTION:A semiconductor element 11 having bumps 14 of HA in height and A in hardness, is connected to a wiring substrate 12 to be mounted, with conductive microparticles 15 of PHIB (HA<=PHIB) in particle size and B (A<B) in hardness in-between. For the purpose, the semiconductor element chip is heated and compressed with the bumps, HA in height and A in hardness, covered with the conductive microparticles 15, PHIB (HA<=PHIB) in particle size and B (A<B) in hardness, abut on the connection regions on the wiring substrate 12.

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 a method of manufacturing the same, and more particularly to face-down bonding connection between a semiconductor element and a substrate.

[0002]

2. Description of the Related Art In recent years, as a method of mounting a semiconductor device thinner and with higher density, a semiconductor element is mounted and connected on a mounting substrate by using a resin, and an electrical connection is performed by using a wire. Instead of the so-called wire bonding mounting, face-down mounting technology has been developed in which bumps are formed on a semiconductor element and directly connected to a substrate for mounting. Face-down mounting is a flip-chip mounting technology applied to supercomputers and COG (Chip on chip) applied to liquid crystal displays.
It can be divided into

In this COG mounting, it has been a general method to electrically connect a semiconductor element and a substrate with a projection called a bump and mechanically connect with a resin. As one method of COG mounting, as shown in FIG. 10, the semiconductor element 1 is connected to the wiring 4 on the substrate 2 with solder bumps 3 formed on the semiconductor element and having a low melting point and a low hardness.
Although a technique has been proposed in which the initial connection is performed by pressing the resin without using a connecting resin, in this method, the solder bumps are melted and alloyed with the wiring on the substrate to make the connection. When a metal such as aluminum which is hard to be wetted by solder is used, the bump itself cannot make a sufficient mechanical connection, and a resin is always required for the connection.

Further, in this method, when the wiring on the substrate side is made of a metal such as aluminum that easily forms a strong oxide film, the surface of the wiring is covered with the oxide film at the time of connection, and the oxidation thereof occurs. There is a problem that the connection reliability is low because the film cannot be sufficiently destroyed.

As a method of destroying the oxide film, there is a method of connecting via fine conductive particles. In this method as well, although the fine conductive particles destroy the aluminum oxide film at the time of connection to make the connection, It was only for obtaining electrical connection, and mechanical connection had to be obtained by resin, and there were problems that the allowable current value was small and the connection resistance was high. Further, in this COB mounting, since electrical connection is achieved when the resin is cured, there is also a problem that even if a defect occurs, it is difficult to repair.

[0006]

As described above, in the conventional face-down connection, when the wiring is made of a material such as aluminum which is easily oxidized, the surface of the wiring is covered with an oxide film at the time of connection. There was a problem that the film could not be sufficiently broken and good connection could not be made.

The present invention has been made in view of the above circumstances, and a mounting structure and a mounting method of a semiconductor device capable of achieving a highly reliable connection with a small connection resistance even in an easily oxidized wiring such as aluminum. The purpose is to provide.

[0008]

Therefore, in the present invention, a semiconductor element having bumps of height H _A hardness A is formed on a wiring board for mounting with a grain size Φ _B (H _A ≦ Φ _B ), a hardness B ( A <B)
It is characterized in that they are connected via the minute conductive particles.

In the method of the present invention, the grain size Φ _B ( _HA ≦ Φ _B ), hardness B (A
The semiconductor element chip is heated and pressed so that the bumps of height H _A hardness A covered with the minute conductive particles of <B) come into contact with each other, and the semiconductor element is connected to the wiring board via the minute conductive particles. And a step of performing.

[0010]

According to the present invention, since the connection with the wiring is made through the pattern composed of the fine conductive particles formed on the bump, even when the oxide film is formed on the wiring surface, Since the fine conductive particles having a hardness higher than that of the bumps are used, the fine conductive particles can destroy the oxide film without being crushed, and good connection can be achieved in a state where the fine conductive particles are surrounded by the bumps.

Further, there is no insulating resin residue at the connection interface,
Connection with high allowable current and low connection resistance is possible.

Furthermore, since the fine conductive particles are selectively formed in the connection region, highly reliable connection can be performed even for fine pitch wiring.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is an explanatory view showing a semiconductor device according to an embodiment of the present invention.

In this semiconductor device, a semiconductor chip 11 is connected to an aluminum wiring 13 formed on a wiring substrate 12, and indium (bonding pad between the semiconductor chip 11 and the wiring 13 is formed as a bonding pad). In order to connect via bumps 14 made of (In) / lead (Pb) and resin balls patterned in the connection area of wiring 13 with minute conductive particles 15 of 13 μm in diameter coated with nickel (Ni) plating layer It is characterized by having done.

Next, the manufacturing process of this semiconductor device will be described.

As shown in the flow chart of FIG. 2, this method includes a wiring substrate forming process 100, a semiconductor chip forming process 200, a transfer substrate forming process 300 for forming a fine conductive particle pattern, It is composed of four processes including a mounting process 400 for mounting using these.

As shown in FIG. 3 (a), the wiring board is formed by forming an aluminum oxide thin film on the glass substrate 20 by a vacuum deposition method, patterning it by photolithography, and then using aluminum as shown in FIG. 3 (b). A wiring pattern 21 made of is formed.

Further, as shown in FIG. 4A, the semiconductor chip forming process 200 is performed by vacuum deposition on a bonding pad 32 formed of an aluminum pattern formed on a surface of a silicon substrate 31 on which a desired element region is formed. A titanium / copper layer is formed as the metal layer 33 (FIG. 4 (b)).

Then, as shown in FIG. 4 (c), a resist R is coated on this upper layer, patterned, and then immersed in a plating solution and electroplated using the barrier metal layer as an electrode to expose the barrier metal layer from the resist. Bumps 14 of indium (In) / lead (Pb) layer are selectively formed on the surface 33 (FIG. 4 (d)).

Finally, as shown in FIG. 4 (e), the resist R
Is removed, the barrier metal layer is removed by etching using the bumps 14 as a mask, and the semiconductor chip provided with the bumps is completed.

Further, a transfer substrate forming process 300.
As shown in FIG. 5 (a), fine conductive particles 15 having a particle diameter of 13 μm in which resin balls are coated with a nickel (Ni) plating layer are dispersed on a transfer substrate 40 through a screen 41,
The squeegee 42 is used to uniformly arrange the fine conductive particles 15 on the transfer substrate (FIG. 5 (b)). Although only the fine conductive particles 15 are formed by printing here, a mixture of the fine conductive particles 15 with a resin paste may be used.

In mounting, first, the semiconductor chip 11 on which bumps are formed so that the bumps come into contact with the pattern of the fine conductive particles 15 on the transfer substrate 40 thus formed (FIG. 6A). After making contact, and applying pressure while heating below the melting point of indium / lead to bury the fine conductive particles on the bumps, pull them up as shown in FIG. 6 (b), and as shown in FIG. 6 (c). The fine conductive particles 15 are selectively attached only on the bumps. Here, it is assumed that the fine conductive particles 15 of about several layers are formed. In this method, since the fine conductive particles 15 are selectively formed only on the bumps by utilizing the height of the bumps, a fine pattern can be easily formed.

In this way, the semiconductor chip in which the fine conductive particles 15 are buried in the bumps 14 is brought into face-down contact with the connection area of the aluminum wiring pattern 13 of the wiring board as shown in FIG. 7 (a). By applying heat and pressure, they are joined by pressure welding as shown in FIG. 7 (b). The pressure at this time is set higher than the pressure at the time of transfer.

Finally, as shown in FIG. 7C, resin sealing is performed to complete the semiconductor device. Since the semiconductor device formed in this way is connected in such a structure that the oxide film formed on the aluminum wiring is destroyed by pressure contact with the fine conductive particles, and the bumps surround the fine conductive particles, the allowable current value is increased. It is possible to reduce the connection resistance and improve the heat dissipation.

Although the bumps are formed of indium / lead and the fine conductive particles are formed of nickel in the above embodiment, the combination is not limited to these, and the hardness, the grain size, and the bump height are H. _A ≤ Φ _B A <B H _A : bump height, A: bump hardness, Φ _B : grain size, B:
Any combination that satisfies the relationship of the hardness of the fine conductive particles may be used. For example, bumps such as copper, nickel, gold, tin / lead, indium / lead,
Indium / tin, bismuth / tin / lead, etc. may be used. The fine conductive particles may be copper, nickel, tin / lead metal particles, or resin balls on which a plating layer of nickel or gold is formed.

If the yield of semiconductor elements and mounting is high,
Resin is potted in advance before mounting,
You may make it harden | cure simultaneously with the connection of a wiring and a bump. When the fine conductive particles are applied to the transfer substrate, the adhesive resin and the fine conductive particles may be applied in a mixed state, transferred to the semiconductor substrate, and pressed against the substrate. Further, the fine conductive particles may be directly applied onto the substrate or the semiconductor element without transferring. When applying, it is possible to utilize the adhesiveness of the resin or to selectively arrange the fine conductive particles by printing. Further, as shown in FIG. 8 (a), by applying the fine conductive particles 15 mixed with resin further, it is firmly fixed as shown in FIG. 8 (b), so that the resin sealing step after mounting is performed. It can be omitted, and the resin sealing step after mounting can be omitted. In this structure, the hardness B of the fine conductive particles is A <
Since it is hard so as to satisfy B, the oxide film can be easily destroyed and good connection can be achieved.

Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

In this example, first bumps are formed as shown in FIG.
The bumps 14a and the second bumps 14b have a two-layer structure. Here, the first bump 14a is made of gold and the second bump 14b is made of indium / tin. By adopting a two-step bump structure of gold bump / indium / tin bump, the bump height can be increased and the structure is resistant to thermal shock.
Due to the presence of the bumps 14a, the spread of the second bumps can be suppressed at the time of connection and the occurrence of a short circuit can be suppressed, so that fine pitch connection can be achieved. Other parts are the same as those in the first embodiment.

That is, in this semiconductor device, the aluminum wiring 1 in which the semiconductor chip 11 is formed on the wiring substrate 12 is used.
The first bump 14a made of gold and formed on the bonding pad between the bonding pad of the semiconductor chip 11 and the wiring 13 and indium /
Nickel fine conductive particles 15S patterned in the connection region between the second bump 14b made of tin and the wiring 13
And the semiconductor chip and the wiring board are sealed with resin 16.

Here, between the hardness A of the first bump, the hardness C of the second bump and the hardness B of the fine conductive particles, C <A,
It is desirable that the relationship of C <B or the relationship of C <A <B be satisfied. Further, it is desirable to select the first bump that does not melt at the bonding temperature.

In the above embodiment, the first bump is gold,
Although the second bump is made of indium / tin, a stable connection can be obtained even when the gold bump is made of a harder copper bump and the second bump is made of tin / lead. The bumps may be continuously formed by electroplating.

Furthermore, it is desirable that the fine conductive particles have a crushed shape rather than a spherical shape for the purpose of destroying the oxide film. Furthermore, by changing the particle size of the fine conductive particles, it can be divided into those that destroy the oxide film and those that control the electrical connection.To further destroy the oxide film, mix harder diamond powder as the fine conductive particles. Further, it is possible to exert the effect more by using the particles obtained by metal-plating the diamond powder. It is also effective to select a material system that stabilizes the connection by removing an oxide film on the surface of the wiring and causing an oxidation-reduction reaction due to a chemical property such as a contact potential between the wiring material and the fine conductive particles.

[0034]

As described above, according to the present invention, the connection with the wiring board on which the wiring pattern made of a material that is easily oxidized is formed is reliable and highly reliable. A semiconductor device having the semiconductor device can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing manufacturing steps of the semiconductor device.

FIG. 3 is a view showing a manufacturing process of the same semiconductor device.

FIG. 4 is a view showing a manufacturing process of the same semiconductor device.

FIG. 5 is a view showing a manufacturing process of the same semiconductor device.

FIG. 6 is a view showing a manufacturing process of the semiconductor device.

FIG. 7 is a view showing a manufacturing process of the same semiconductor device.

FIG. 8 is a diagram showing another embodiment of the present invention.

FIG. 9 is a diagram showing a semiconductor device according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a conventional semiconductor device.

[Explanation of symbols]

 1 Semiconductor Element 2 Substrate 3 Bump 4 Wiring 11 Semiconductor Chip 12 Wiring Board 13 Aluminum Wiring 14 Bump 15 Minute Conductive Particle

Claims (2)

[Claims] 1. _A height H _A hardness A on a mounting wiring board.
A semiconductor element having bumps of grain size Φ _B (H _A ≦
Φ _B ), hardness B (A <B), and a semiconductor device characterized by being connected via fine conductive particles. 2. A step of forming a bump having a height H _A hardness A on a semiconductor element in which an element region is formed, and a grain size Φ _B (H _A ≦ Φ _B ) and a hardness B on the bump surface.
The step (A <B) of forming the fine conductive particle layer is performed, and the semiconductor element is heated while the bumps covered with the fine conductive particle layer are brought into contact with the connection area on the wiring board for mounting. And a step of connecting the semiconductor element to the wiring board via the fine conductive particles by applying pressure.