JP2001244294A - Method of mounting fine chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of mounting a fine chip such as a semiconductor chip by which a fine semiconductor chip or the like can be mounted at a desired place on a substrate efficiently with high yield. SOLUTION: The mount substrate 6 is dipped in a solution 2 scattered with fine chips (LED chips 3) to assemble the fine chips on the substrate in a self-hold manner. In this method of mounting a fine chip, bubbles 5 are generated on the mounting face of the substrate to control the assembling positions of the fine chips.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for mounting a fine chip. More specifically, the present invention relates to a method for mounting a fine chip in which a number of microscopic semiconductor chips of a micron size are mounted on a substrate.

[0002]

2. Description of the Related Art In the case of forming various devices by incorporating a functional element consisting of a semiconductor chip such as an LED or IC having a fine structure on a substrate, the semiconductor chip is formed into, for example, a trapezoidal shape by etching, and the substrate is supported. A fine semiconductor chip is mounted on a substrate by providing a concave portion to be formed and mounting a semiconductor chip in the concave portion.

However, according to this method, it is difficult to mount a material or a semiconductor chip having a small size in which a trapezoid cannot be easily formed by etching or the like, or the accuracy of the shape or assembly is reduced, and the yield is deteriorated. I do.

When a semiconductor chip such as a light emitting element for a display is mounted on a substrate, it is necessary to efficiently mount the semiconductor chip on a substrate surface having a predetermined area with high yield, and it is also 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.

A conventional method for mounting a fine chip such as a semiconductor chip is disclosed in US Pat. Nos. 5,545,291 and 58241.
No. 86, No. 5904545, Tokuhyo Hei 9-50674
2, JP-A-9-120943, and the like. The mounting methods described in these methods are methods in which a chip is tapered to determine the upper and lower sides, and the chip is embedded in a depression of the substrate. On this occasion,
The chips are mixed into 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 fine chip,
A method of assembling an integrated circuit on a substrate by electrostatic force is described in US patent application Ser. No. 07 / 902,986. In this method, the chips are vibrated by electrostatic force, and the chips are arranged in a state where the potential energy is minimized.

[0007]

However, in the above method of providing a taper on a semiconductor chip or the like, the yield is sufficiently large in a structure having a chip outer shape of about several hundred μm.
If the size is several tens μm or smaller, the yield decreases, and there is a problem in practical use.

Further, the above-mentioned conventional method using electrostatic force requires an apparatus for vibrating particles with electrostatic force. Further, in this method, since the fine chips are mechanically vibrated, the 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 method of mounting a fine chip such as a semiconductor chip which can efficiently mount a fine semiconductor chip at a desired position on a substrate with a high yield.

[0010]

In order to achieve the above object, according to the present invention, a mounting substrate is immersed in a solution in which fine chips are scattered, and the mounting of the fine chips on the substrate in a self-holding manner. In the mounting method, there is provided a method for mounting a fine chip, characterized in that bubbles are generated on a mounting surface side of the mounting substrate to control a mounting position of the fine chip.

According to this structure, the bubbles are generated in a place where the fine chips are not to be incorporated, so that the fine chips are hindered by the bubbles and are not adsorbed at the place, thereby controlling the electric field gradient to another place. The mounting position of the microchip can be reliably controlled in combination with the suction force of the microchip.
In this case, the microchip to be incorporated is mounted on the mounting substrate in a self-aligned and self-holding manner by being attracted by an electric field or a magnetic field or coupling by shape matching while floating in a solvent.

In a preferred configuration example, the counter electrode facing the mounting substrate is immersed in the solvent, a voltage is applied between the mounting substrate and the counter electrode, and the mounting position of the fine chip is controlled by controlling the electric field gradient by the voltage. In addition to the control, the air bubbles are generated by an electrolysis reaction of the mounting substrate.

According to this structure, the fine chip is incorporated into the mounting substrate by the electric field gradient without using the physical force based on the chip shape, so that the fine particles such as the semiconductor chip can be surely mounted. In addition, by applying the voltage, an electrolysis reaction can be caused at a desired position on the mounting substrate to generate bubbles, and it is possible to prevent the fine chip from being attracted to a place other than necessary.

In a preferred embodiment, the solvent is circulated.

According to this structure, a large number of fine chips scattered in the solvent are successively approached to the mounting substrate at a certain probability while being circulated, and are sucked to the mounting position by the electric field gradient, and are not required. Since the suction is prevented by air bubbles, a large number of fine chips can be efficiently and reliably mounted in one process.

The present invention shows a method for assembling an element having a fine structure on a substrate and a structure obtained by the method. In particular, in the method of the present invention, a microstructure is conveyed through a fluid onto the upper surface of a substrate having a joint or a receiving portion (not necessarily a depression), and a portion of the substrate where the microstructure is not desired to be adsorbed. By generating air bubbles, the fine structure is mounted at a desired position while preventing adsorption to portions other than the necessary portions. At the time of this transfer, the microstructures are self-aligned and united in an assembly portion such as a depression by the action of a force such as an electric field. The combined structure thus obtained is a display device or a signal processing device in which light emitting diodes (LEDs) are combined on a substrate on which wiring is formed. Examples of elements or structures (fine chips) having a fine structure include lasers, transistors, gun oscillators, integrated circuits, solar connectors, and fine phosphor particles. As another example of the combined structure, there is a structure in which a semiconductor device is combined with a substrate such as another semiconductor element or another plastic.

The method of the present invention is a method of assembling a chip having a microstructure on the order of microns on a substrate. The substrate has a portion for accommodating a structure and a region other than that on the upper surface (not necessarily a concave portion). No) A silicon substrate, a gallium arsenide substrate, a glass substrate, a ceramic substrate, a plastic substrate, or the like, or one having at least one region having a receiving portion by wiring on the above-described substrate. It may be a plastic sheet.

The assembling step includes a step of preparing a microstructured chip, a step of transporting the microstructured (chip) into a fluid to form a mixture or generally a slurry,
There is a step of optimizing the control of the speed and the control of the external force and the like such that the slurry is arranged in the region having at least one microstructure in the receiving portion, and self-aligning the slurry. Bubbles are generated in this self-alignment step to reliably control the mounting position.

The present invention further provides an apparatus for assembling a microstructure on a substrate having at least one region where the microstructure is to be assembled and at least one other region. The apparatus includes a (voltage) power supply for controlling an electric field for accommodating a substrate, a fluid, and, if necessary, a device having a microstructure, and a pump for circulating the device having the microstructure. Further, an ultrasonic oscillator for generating bubbles may be provided.

The method of the present invention and the structure obtained thereby are, for example, a method of mounting a GaAlP-based LED chip on a glass substrate and the obtained structure. The shape of the chip is cylindrical, pyramid, rectangular parallelepiped, cubic, T
Shapes, grain shapes, other shapes and combinations thereof may be used, regardless of symmetrical or asymmetrical shapes. Generally, the shape of the device allows it to be tightly inserted into the desired area of the substrate. Microstructured chips include GaAlAs, gallium nitride, silicon, diamond, germanium, and other III-
It may be a compound of a group V element and a group II-VI element and a multilayer structure thereof. The multilayer structure can include metals, insulators such as silicon oxide and silicon nitride, and combinations thereof.

The chips having the fine structure are mixed in a solvent to form a slurry-like mixed solution. The mixture is circulated by a circulation device so as not to sink, and an assembly substrate (mounting substrate) and an auxiliary electrode (opposite electrode) for assembling and mounting a chip in the circulating liquid are arranged and connected to a voltage power supply. . However, since the chip can be prevented from sinking due to the difference in specific gravity from the chip depending on the type of the solvent, it is not necessary to circulate the solvent in that case.

By assembling the slurried fine chips or particles at a desired position by utilizing the force of the electric field gradient and the effect of electrolytic etching (electrolysis), the fine chips can be precisely positioned at a predetermined position. Can be implemented with a filling rate. Bubbles are generated by this electrolysis. in this case,
Electrodes are formed on the mounting board so that, for example, a matrix or other position can be selected, the electric field is controlled by each electrode position, the fine chip is selectively sucked by the applied voltage, and air bubbles are generated at positions other than the suction part. Can be.

A plurality of layers of electrodes are formed on the substrate used for mounting. The electrode on the outermost surface or the electrode material not to be mounted may be a metal which is easily electrolyzed, for example, Al.
And Zn are suitable, but other metals may be used as long as they are easily electrolyzed. The electrodes are produced by vapor deposition, plating or any other suitable method.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of an apparatus for implementing a mounting method according to the present invention. A large number of fine LED chips 3 are mixed in a solvent 2 contained in a container 1 to form a slurry-like solution. This LED chip 3
Is circulated by the pump 4. The mounting substrate 6 into which the LED chip 3 is to be mounted and the counter electrode 7 disposed opposite to the mounting substrate 6 are immersed in the solvent 2. Mounting board 6
Are formed with a large number of electrodes (not shown) corresponding to chip mounting positions. A voltage can be selectively applied to these electrodes by the power supply 8. An electrode may be formed so that the voltage on the counter electrode side can be controlled according to the position.

In this embodiment, an electrolysis reaction is caused by applying a voltage between the mounting substrate 6 and the counter electrode 7 in the solvent 2 to generate bubbles 5 (for example, H 2) from the surface of the mounting substrate 6. By selecting an electrode on the mounting substrate 6 side and applying a voltage, the position where the bubble 5 is generated can be controlled. As a result, bubbles 5 are generated at electrode positions where the LED chip 3 is not desired to be incorporated, and self-adsorption of the LED chip 3 by self-alignment based on the electric field gradient can be prevented.

In this embodiment, the mounting substrate 6 is formed by applying two layers of wiring metal (an upper layer electrode and a lower layer electrode shown in FIG. 4 described later) on a glass substrate. (Chip receiving part) GaAlP LED
Mount the chip. This mounting step includes a step of preparing an LED chip, a step of mixing the chip in a solvent to form a slurry, and a step of sinking the chip into a recessed portion of the substrate by using the force of an electric field gradient or the like. . Through these steps, the chip is mounted at a predetermined position at a predetermined filling rate. When assembling the LED chip on the glass substrate in this way,
The chip is sucked into the recessed portion (chip receiving portion) at a predetermined position on the upper surface of the glass substrate, and is assembled and self-aligned at that position. At this time, the suction of the chip to an unnecessary portion is prevented by the generation of the bubble whose position is selected.

FIG. 2 shows the structure of the LED chip 3.
As shown, this LED chip 3 is made of n-GaAs.
On the chip substrate 3a made of, for example, n-Ga0.
30 nm thick buffer layer 3 made of 5In0.5P
b and n- (Al0.7Ga0.3) 0.5In0.5
A first conductive layer 3c also serving as an etching stop layer having a thickness of 400 nm and made of (Al0.5Ga0.5) 0.
A 30 nm thick first carrier confinement layer 3d made of 5In0.5P, a light emitting layer 3e made of 15QWGaInP-AlGaInP, and (Al0.5Ga0.5) 0.5
A 30 nm-thick second carrier confinement layer 3f made of In0.5P and p- (Al0.7Ga0.3) 0.5In
A second conductive layer 3g having a thickness of 400 nm and a thickness of 400 nm,
It is formed by laminating a 30 nm-thick contact layer 3h made of p-Ga0.5In0.5P.

The shape of the LED chip 3 is, for example, about 5
It is a cube of 0 μm square. Such an LED chip 3
Is manufactured by laminating each layer on a substrate according to a normal LED chip manufacturing process and separating the layers. Separation of the chip from the substrate is performed by wet etching, dry etching, or the like, and the substrate is thinned by about 10 μm by back surface polishing, wet etching, or the like. However, after the chip is separated from the substrate, the process of forming an electrode on the back surface is completed, and the process is performed in a state where the chip is attached to an auxiliary substrate such as glass until the slurry is formed.

After the p-electrode and the n-electrode are manufactured by the above-mentioned method, and after checking the non-defective products and the like, the glass auxiliary substrate is immersed in a solvent, and the chips are completely separated and dispersed in the solvent. After washing several times, it is slurried with a solvent used for mounting and assembling.

FIG. 3 is a plan view of the mounting surface of the mounting board 6. The mounting substrate 6 is a substrate constituting an LED display screen, and three types of LED chips 3 of R, G, and B are arranged in a matrix in a certain order. In this case, each of the R, G, and B LED chips 3 forms a slurry of R, G, and B alone in which only the chips are scattered, and is mounted in a separate process using each of the slurries. For example, first, the mounting substrate 6 is immersed in the slurry of R, an electric field gradient is formed by voltage control of the electric field in the R chip mounting portion of the substrate, and the R LED chip is sucked and mounted. Next, the substrate on which the R chip is mounted is immersed in the slurry of G, and the G LED chip is mounted by voltage control using an electric field gradient. Finally, the B LED chip is mounted in the slurry of B. .

FIG. 4 is a sectional view of the mounting board 6 of this embodiment. A lower electrode 6b made of, for example, Ti / Au is formed on a glass substrate 6a by vapor deposition or plating.
An insulating film 6c made of SiO2 is formed thereon, and an upper electrode 6d made of Au / Al is formed thereon by patterning by vapor deposition or plating. These electrodes and insulating films can be formed by a thin film forming process by photolithography. The chip receiving portion 6e is formed by the step of the two-layer electrode wiring structure. The two-layer electrode wiring is patterned in, for example, a matrix.

The counter electrode 7 is formed by depositing or depositing a metal such as Au on the entire upper surface of a metal plate or a glass plate having substantially the same size as the mounting substrate 6.

The mounting substrate 6 and the counter electrode 7 as described above
Is immersed in the solvent 2 in the form of a slurry as shown in FIG. 1, and the pump 2 circulates the solvent 2 together with the LED chips 3 so that the chips do not sink. In this state, power supply 8
By appropriately controlling the voltages of the two positions of the mounting substrate 6 and the counter electrode 7, the LED chip 3 is sucked and held in the chip receiving portion 6e at a desired position.

As an example of the process conditions of the embodiment, the distance between the mounting substrate 6 and the counter electrode 7 was 1 cm, and the applied voltage was 100 V. A voltage of 5 V is applied between the upper electrode 6d and the lower electrode 6b of the mounting substrate 6,
The selection of a chip in the mounting substrate 6 was performed by controlling the distribution of electric fields and the distribution of bubbles generated by electrolysis.

In the above embodiment, bubbles are generated by electrolysis. However, bubbles can be forcibly generated using an ultrasonic oscillator or the like.

In the above embodiment, the LED chip 3 is self-aligned and self-holdingly adsorbed to the substrate by using a radio wave gradient. Alternatively, a magnetic field may be used to utilize magnetic attraction. Further, the present invention can be applied to a case in which the shapes of the chip-side and substrate-side receiving portions are made to correspond to each other to perform self-alignment based on shape consistency.

[0037]

As described above, according to the present invention, bubbles are generated in places where fine chips are not to be incorporated, so that the fine chips are obstructed by the bubbles and are not adsorbed at those places, and are not transferred to other places. The mounting position of the fine chip can be reliably controlled in combination with the suction force by the electric field gradient control or the like. As a result, the yield when mounting microchips on the order of microns is greatly improved to about 100%. In addition, since the chip is reliably removed from the chip suction unnecessary portion on the substrate surface, post-processing of the substrate can be efficiently and easily performed.

Further, if fine chips are scattered in a solvent and bubbles are generated by electrolysis using an electric field gradient and adsorption is performed by self-alignment, a large number of fine chips of the same type are simultaneously mounted in one process. It is possible,
The efficiency of the process is increased, the productivity is improved, the manufacturing process of the substrate is simplified, and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for performing a microchip mounting method according to the present invention.

FIG. 2 is a configuration diagram of an LED chip to which the present invention is applied.

FIG. 3 is a plan view of a mounting substrate to which the present invention is applied.

FIG. 4 is a configuration diagram of a mounting board according to the embodiment of the present invention.

[Explanation of symbols]

1: container, 2: solvent, 3: LED chip, 4: pump
5: air bubble, 6: mounting board, 7: counter electrode, 8: power supply.

Claims (3)

[Claims] 1. A method of mounting a microchip in a solution in which microchips are scattered, and mounting the microchip on the substrate in a self-holding manner, wherein bubbles are generated on the mounting surface side of the mounting substrate. A method for mounting a fine chip, wherein the mounting position of the fine chip is controlled. 2. A method for immersing a counter electrode facing a mounting substrate in the solvent, applying a voltage between the mounting substrate and the counter electrode, and controlling an electric field gradient by the voltage to control a mounting position of the fine chip. 2. The method according to claim 1, wherein the bubbles are generated by an electrolysis reaction of the mounting substrate. 3. The method according to claim 1, wherein the solvent is circulated.