JP2001237266A - Semiconductor chip and its mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor chip and its mounting method in which a micro semiconductor chip can be mounted efficiently at a desired position on a substrate with high yield. SOLUTION: A semiconductor chip 1 where a part, including the bonding face to a substrate 8, is composed of a ferromagnetic material or a ferrimagnetic material (soft ferromagnetic material 4, hard ferromagnetic material 5) is bonded while being attracted by magnetic attraction to the electrode 9 of the substrate 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor chip and a method for mounting the same. More specifically, the present invention relates to a method for mounting a semiconductor chip for bonding a semiconductor chip to a substrate electrode.

[0002]

2. Description of the Related Art When a semiconductor chip such as a light emitting element for a display is mounted on a substrate, it is necessary to mount the semiconductor chip on a substrate having a predetermined area efficiently and with good yield, and it is necessary to consider cost. In addition, due to miniaturization of semiconductor chips, handling during mounting is becoming difficult. Therefore, there is a demand for a semiconductor chip structure and a mounting method thereof that can effectively deal with such points.

Conventional semiconductor chip mounting methods are disclosed in US Pat. Nos. 5,545,291, 5,824,186, and 59.
04545, Japanese Translation of PCT International Publication No. 9-506742, and JP-A-9-19-1
20943 and the like. In the mounting methods described in these, the upper and lower sides are determined by providing a taper to the semiconductor chip,
This is a method of embedding in the depression of the substrate. At this time, the semiconductor chip is mixed with a solution such as water or alcohol to form a slurry, and the slurry is flown over the substrate.

As another conventional method for mounting a semiconductor chip, a method of assembling an integrated circuit on a substrate by electrostatic force is described in US Patent Application No. 07/902986.
In this method, particles are vibrated by electrostatic force, and semiconductor chips are arranged in a state where potential energy is minimized.

[0005]

However, in the above-described method of providing a taper in a semiconductor chip, the yield is sufficiently large for a structure having a chip outer shape of about several hundred μm, but the yield is small for a structure having a size of several tens μm or less. And there is a problem in practical use.

Further, the above-mentioned conventional method using electrostatic force requires a device for vibrating particles with electrostatic force. Further, in this method, since the semiconductor chips are mechanically vibrated, the semiconductor chips may collide with each other and may be partially damaged, which is not suitable for practical use.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned prior art, and has as its object to provide a semiconductor chip capable of efficiently mounting a minute semiconductor chip at a desired position on a substrate with good yield and a method of mounting the semiconductor chip.

[0008]

According to the present invention, there is provided a semiconductor chip characterized in that a part including a bonding surface to a substrate is made of a ferromagnetic material or a ferrimagnetic material. I do.

According to this structure, the ferromagnetic material or ferrimagnetic material magnetically acts on the electrode made of a magnetic material provided on the substrate side, and the semiconductor chip is joined to the substrate by magnetic attraction.

In a preferred configuration example, the semiconductor chip has a supporting member mounted with a semiconductor element and joined to a substrate, and the ferromagnetic material or the ferrimagnetic material is exposed at a joining surface of the supporting material to the substrate. It is characterized by having a body.

According to this structure, the semiconductor element is mounted on the supporting material, and the ferromagnetic material or the ferrimagnetic material exposed on the bonding surface of the supporting material to the substrate opposite to the semiconductor device mounting surface is formed on the substrate electrode. And the support material is magnetically attracted to the substrate.

Further, according to the present invention, in a semiconductor chip mounting method for bonding a semiconductor chip to an electrode formed on a surface of a substrate, a predetermined part of the semiconductor chip is made of a ferromagnetic material or a ferrimagnetic material. A method for mounting a semiconductor chip, wherein the semiconductor chip is attracted to and joined to a substrate by magnetic attraction between a ferromagnetic or ferrimagnetic material and an electrode of the substrate.

According to this structure, the semiconductor chip is attracted to and bonded to the substrate by the magnetic action of the ferromagnetic or ferrimagnetic material provided on a part of the semiconductor chip. Thus, a very small semiconductor chip can be easily and reliably bonded onto a substrate.

In a preferred configuration example, a plurality of the semiconductor chips are dispersed in a circulation path of a fluid, and the substrate is disposed in the circulation path, so that the circulating semiconductor chips are adsorbed on the substrate electrode. Features.

According to this configuration, the substrate is arranged in the fluid circulation path and the semiconductor chips are dispersed and flowed in the fluid circulation path, so that the semiconductor chip is magnetically attracted to the substrate in the circulation path. Since the semiconductor chips are joined, the semiconductor chips can be joined to the substrate without using a holding mechanism or a transport mechanism for the semiconductor chips, and the handling at the time of joining is improved.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a semiconductor chip according to an embodiment of the present invention. Semiconductor chip 1
Is composed of an LED element 2 made of, for example, AlGaInP and a support member 3 made of, for example, n-GaAs, on which the LED element 2 is mounted. A ferromagnetic material 5 made of a magnetic hard material having a stronger coercive force than the soft material is embedded on the lower surface side of the support member 3 via a layer of a ferromagnetic material 4 made of a magnetic soft material having a relatively weak coercive force. You. The hard ferromagnetic material 5 and the surrounding soft ferromagnetic material 4 are exposed over the entire lower surface of the support member 3 to cover the lower surface of the support member 3.

The soft ferromagnetic material 4 is made of a ferromagnetic material such as iron (Fe) or permalloy or a ferrimagnetic material, and has an ohmic contact at the interface with the support material (n-GaAs) 3 to improve adhesion. Therefore, from the GaAs side,
Pd layer 10 nm, AuGe alloy layer 150 nm, Ti layer 5
0 nm is formed in order, and further, an Fe layer is formed in a thickness of 1 μm and an antioxidant film is formed in a thickness of 100 nm.

As shown in FIG. 2, the hard magnetic material 5 has a long axis 300 nm and a short axis 10
It has a structure in which iron (Fe) particles 6 having an elliptical shape of 0 nm are dispersed in a photocurable resin 7. The iron particles 6 have a single magnetic domain structure and are magnetized in the long axis direction. Since the major axis of the iron particles 6 is oriented perpendicular to the surface of the support 3, the direction (vertical direction) perpendicular to the surface of the support is the easy axis of magnetization of the hard ferromagnetic material 5 as a whole. It may be made of other ferromagnetic material or ferrimagnetic material other than iron.

The size of the semiconductor chip 1 is, for example, that the support material 3 is 20 μm × 20 μm × 10 μm,
The dimensions of the five parts are 14 μm × 14 μm × 7 μm.

FIG. 3 shows the magnetic flux distribution of the semiconductor chip. The magnetic flux does not interact with the other magnetic material in the direction of the upper surface and the side surface because the upper surface and the side surface of the chip are closed by the soft ferromagnetic material 4 and only the lower surface is open. On the other hand, since the magnetic flux is open on the lower surface side of the chip, magnetostatic interaction with other magnetic materials is exerted only on the lower surface side.

FIG. 4 is a plan view of a substrate on which the semiconductor chip is mounted. For example, on a substrate 8 made of glass,
The stripe electrode 9 composed of Ti and Fe has a width of 1
It is formed by patterning with a pattern of 00 μm and a cycle of 1 nm.

FIG. 5 is an explanatory view showing a manufacturing process of the semiconductor chip. First, as shown in (A), a plurality of LED elements 2 are separately formed on the surface of an n-type GaAs support member 3 and a transparent electrode is formed on the surface.
A positive photoresist 10 is applied to both sides. The photoresist 10 on the back side is exposed and developed using a photomask to form a groove for embedding a magnetic material, and is patterned. Next, wet etching is performed in a mixed solution of sulfuric acid, hydrogen peroxide, and water to form a groove 11 as shown in FIG.

Next, on the back surface of the support member 3, 10
nm, AuGe alloy 150 nm, Ti 50 nm,
Fe is deposited to a thickness of 1000 nm to form a soft ferromagnetic material 4 as shown in FIG. At this time, these metals are also formed on the side surfaces in the grooves 11 by revolving the support member 3 while rotating. Next, heat treatment is performed at 180 ° C. for 5 minutes in a reducing gas atmosphere to form an alloy.

Subsequently, the above-mentioned iron powder is dispersed in a photo-curing resin, adjusted to an appropriate viscosity by n-hexane, applied to the groove 11 on the back surface of the support material, and then photo-cured in a magnetic field of 10 kOe. Then, as shown in FIG.
To form Thereafter, each LED element is divided by opening the wall.

Next, a method for mounting the semiconductor chip will be described. First, a plurality of the semiconductor chips are dispersed in a polar solvent such as water and circulated by a pump or the like. The substrate is placed in this circulation path. In this case, a polar solvent or a non-polar solvent is appropriately selected in consideration of the hydrophilicity and hydrophobicity of the semiconductor chip. Ga constituting the support of the present embodiment
Since As has high hydrophilicity, water is used as a polar solvent to prevent aggregation of chips and improve dispersibility.

An electrode 9 made of a ferromagnetic material such as Fe on a substrate arranged in the circulation path with a certain probability of a part of the semiconductor chips dispersed in the circulation path (see FIG. 4).
Flows close to As described above, the semiconductor chip approaching the magnetic electrode of the substrate and having the back surface facing the direction of the substrate electrode,
By the magnetostatic interaction of the ferromagnetic materials 4 and 5 embedded on the back surface of the support member, the back surface of the chip is magnetically attracted to the substrate electrode, and the semiconductor chip is joined to the substrate.

FIG. 6 shows a magnetic flux distribution state of a semiconductor chip magnetically bonded on a substrate. As shown, the electrode 9
Is composed of a Ti layer 9a, an Au electrode layer 9b, and an Fe electrode layer 9c formed on a glass substrate 8. In this joined state, the magnetic flux generated by the hard ferromagnetic material 5 formed on the semiconductor chip 1 is reduced by the soft ferromagnetic material 4 surrounding the hard ferromagnetic material 4.
And is enclosed by the iron electrode 9c of the mounting substrate 8 and is closed and does not leak outside.

When another semiconductor chip 1 'approaches the electrode of the substrate 8 to which one semiconductor chip 1 has already been joined so as to further overlap as shown in FIG. 1 'has a weak magnetic interaction, but the magnetic interaction is farther apart than the interaction between the semiconductor chip 1 and the substrate electrode already joined directly to the substrate electrode. Because it is very weak. For this reason, the semiconductor chip 1 'approached later is not washed away by the fluid and a plurality of semiconductor chips do not overlap on one electrode.

FIG. 8 shows another embodiment of the present invention.
In this embodiment, in addition to the above-described magnetic action between the semiconductor chip and the substrate electrode, a spatial distribution of magnetic flux toward a position to be joined is formed by locally applying an external magnetic field to the substrate 8. By adding an external magnetic field in this way,
The semiconductor chip 1 can be securely joined to the electrode at the required position. In this case, the semiconductor chip 1
Since the soft material ferromagnetic material 4 is magnetized, some magnetic flux leaks to the outside, and the semiconductor chip overlaps and couples around the electrode. With the magnetic flux distribution shown in FIG. 6, only the semiconductor chip directly connected to the electrode remains on the electrode.

When the semiconductor chip is mounted on the substrate by the magnetic method as described above, the soft ferromagnetic material of the semiconductor chip and the magnetic electrode of the mounting substrate are in direct contact, and these are used as electrodes. be able to.

[0031]

As described above, according to the present invention, the semiconductor chip is attracted to and joined to the magnetic electrodes of the substrate by the magnetic action of the ferromagnetic or ferrimagnetic material provided on a part of the semiconductor chip. Therefore, a minute semiconductor chip can be easily and reliably joined to the substrate simply by bringing the semiconductor chip close to the substrate surface, and a large number of semiconductor chips can be efficiently mounted at desired positions with high yield.

In this case, by providing the magnetic material at a predetermined position on the semiconductor chip so as to be exposed, it is possible to control the position and orientation of the semiconductor chip on the substrate as well as the direction and orientation thereof. In addition, a plurality of semiconductor chips are not overlapped and joined at the same time at the mounting location, and the joining reliability is high. Further, the magnetic material of the semiconductor chip used for bonding can be used as an electrode as it is.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor chip according to the present invention.

FIG. 2 is a configuration explanatory view of a hard material ferromagnetic material of the semiconductor chip of FIG. 1;

FIG. 3 is an explanatory diagram of a magnetic flux distribution around the semiconductor chip of FIG. 1;

FIG. 4 is a plan view of a substrate on which the semiconductor chip of the present invention is mounted.

FIG. 5 is an explanatory diagram of a semiconductor chip manufacturing process of the present invention.

FIG. 6 is an explanatory view of a magnetic flux distribution in a mounted state of the semiconductor chip of the present invention.

FIG. 7 is an explanatory diagram of a bonding operation of the semiconductor chip of the present invention.

FIG. 8 is an explanatory diagram of a magnetic flux distribution according to another embodiment of the present invention.

[Explanation of symbols]

1, 1 ': semiconductor chip, 2: LED element, 3: support material, 4: soft material ferromagnetic material, 5: hard material ferromagnetic material,
6: iron particles, 7: photocurable resin, 8: substrate, 9: electrode, 1
0: photoresist, 11: groove.

Claims (4)

[Claims] 1. A semiconductor chip wherein a part including a bonding surface to a substrate is made of a ferromagnetic material or a ferrimagnetic material. 2. The semiconductor chip according to claim 1, further comprising: a support member mounted with a semiconductor element and bonded to a substrate, and provided with said ferromagnetic material or ferrimagnetic material exposed at a bonding surface of said support material to said substrate. The semiconductor chip according to claim 1, wherein: 3. A method of mounting a semiconductor chip in which a semiconductor chip is joined to an electrode formed on a surface of a substrate, wherein a predetermined part of the semiconductor chip is made of a ferromagnetic material or a ferrimagnetic material. Alternatively, a method of mounting a semiconductor chip, wherein the semiconductor chip is attracted to and bonded to a substrate by magnetic attraction between a ferrimagnetic material and an electrode of the substrate. 4. A circulating semiconductor chip is adsorbed on a substrate electrode by dispersing a plurality of semiconductor chips in a circulation path of a fluid and disposing the substrate in the circulation path. A method for mounting the semiconductor chip according to claim 3.