JPH11177128A - Semiconductor light emitting element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED chip capable of making even a small-sized LED chip wireless without the danger of short-circuiting and obtaining an extremely thin semiconductor light emitting element and a manufacturing method. SOLUTION: The LED chip 10 is composed of a substrate 1, a light emitting layer formation part 12 formed by providing a semiconductor layer 2 on the substrate 1, a coating layer 3 composed of insulating transparent resin provided on the outer periphery of the light emitting layer formation part 12 and a pair of electrodes 4 and 5 respectively provided on the back surface of the substrate 1 and the surface side of the light emitting layer formation part 12. Thus, since the boundary part of the p-type layer and n-type layer of a semiconductor layer part is coated with a translucent insulator, even when the LED chip 10 is laid fallen and mounted on the substrate and the electrodes 4 and 5 on both sides are electrically connected by a conductive adhesive material directly on the substrate, the danger of short-circuiting between both electrodes does not exist.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin chip type light emitting element having a light emitting element chip bonded to a substrate and having a very low height from the substrate, and a dot matrix display device in which light emitting element chips are arranged in a matrix. The present invention relates to such a semiconductor light emitting device and a method for manufacturing the same. More specifically, the present invention relates to a wireless semiconductor light emitting device that does not require wire bonding and a method of manufacturing the same.

[0002]

2. Description of the Related Art Along with the miniaturization of portable devices such as portable telephones and PHSs, light-emitting devices and the like used for them are required to be light and thin, and in particular, thin chip-type light-emitting devices having a low height are required. .

As shown in FIG. 5A, a small and thin chip type light emitting device of this kind has terminal electrodes 22 and 23 formed at both ends of a substrate 21 and is connected to one of the terminal electrodes 22 to be connected to a terminal. A light emitting diode (hereinafter, referred to as an LED) chip 40 is bonded on an electrode which is a part of the electrode, and its lower electrode is directly connected to the terminal electrode 22, and its upper electrode is connected to the other terminal electrode 23 by a gold wire 27 and a wire. They are bonded and electrically connected to each other. LE
As shown in FIG. 5B, for example, the D chip 40 has a pn junction surface (light emitting layer) formed by joining an n-type semiconductor layer 41 made of GaAs or GaP and a p-type semiconductor layer 42.
43 are formed, and electrodes 44 and 45 are provided on both surfaces thereof. On the front side of the substrate 1, a package 25 for covering and protecting the LED chip 40 and the gold wire 27 with a resin made of a transparent or milky epoxy resin or the like is formed.

The length A and the length B of the LED chip 40 are both about 0.24 to 0.35 mm, and the thickness T is almost the same, and is formed in a substantially cubic shape. The lengths of the vertical A and the horizontal B are generally equal to each other from the viewpoint of wire bonding of a gold wire and from the viewpoint of luminance uniformity. Further, when each length is smaller than the above-described length, the area of the pn junction surface 43 decreases,
If the input power is increased in order to increase the light emission amount in a small area, the semiconductor layer is damaged and the deterioration is accelerated. Therefore, the area of the pn junction surface 43 cannot be reduced too much in order to obtain the required light emission amount of illumination. If the thickness T is reduced, the wafer before dicing into chips may be warped or cracked, making it difficult to stably manufacture the LED elements.
Therefore, even in response to a demand for miniaturization, the cubic shape of the LED chip described above is the limit of miniaturization.

[0005]

As described above, in the conventional chip type light emitting device, the size of the LED chip is at the lower limit in view of the required area of the light emitting layer. In addition, a space for wire bonding above the LED chip is indispensable from the viewpoint of preventing contact by a gold wire or the like. However, with the development and miniaturization of mobile devices such as mobile phones and PHSs, the demand for miniaturization of electronic components has increased further, and chip-type light-emitting elements have been particularly required to be thin. In addition, when a wire such as the above-described gold wire is used, there is also a problem that when a thermal stress is applied, the wire breaks due to fatigue due to expansion and contraction of an epoxy resin covering the periphery thereof.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a semiconductor light emitting device which does not require wire bonding without risk of short circuit even in a small LED chip.

Another object of the present invention is to provide a light emitting device chip having a light emitting layer having an area capable of obtaining a required light emission amount and having a thickness which does not cause any inconvenience in a wafer processing step. An object of the present invention is to provide a semiconductor light emitting device.

It is still another object of the present invention to provide a method of manufacturing a semiconductor light emitting device for obtaining an LED chip which is wireless and has no risk of short circuit.

[0009]

A chip type semiconductor light emitting device according to the present invention comprises a substrate, a light emitting layer forming portion formed by providing a semiconductor layer on the substrate, and an outer periphery of the light emitting layer forming portion. A chip is composed of a coating layer made of a light-transmitting insulator provided on the substrate and a pair of electrodes provided on the back surface of the substrate and the front surface side of the light emitting layer forming portion, respectively.

Here, the light emitting layer forming portion means a semiconductor substrate in which a pn junction is formed by providing a semiconductor layer of a semiconductor substrate on which a semiconductor layer of a different conductivity type is provided, An n-type layer and a p-type layer are laminated or diffused on a substrate or another substrate by pn.
To form a light emitting layer, such as a semiconductor layer portion where a junction is formed, and a semiconductor laminated portion where an n-type cladding layer, an active layer, and a p-type cladding layer are respectively laminated on a substrate to form a double hetero junction. Means the semiconductor layer portion.

With this structure, since the boundary between the p-type layer and the n-type layer of the semiconductor layer is covered with a light-transmitting insulator, the LED chip is placed sideways on the substrate. However, even if the electrodes on both sides are electrically connected directly to the substrate by a conductive adhesive, there is no danger of a short circuit between the two electrodes.

If the substrate and the chip formed of the semiconductor layer provided thereon have a rectangular parallelepiped shape, the thinner light emitting element can be obtained by mounting the substrate such that the narrower one is up and down.

A pair of electrodes of the chip having a rectangular parallelepiped shape are laid sideways so as to oppose each other in a horizontal direction, and the chip is disposed on the mount substrate such that a wide surface of the rectangular parallelepiped shape is in contact with the mount substrate; By bonding the pair of electrodes directly to the connection portion of the substrate with a conductive material,
A thin chip-type light emitting element or an LED dot matrix can be formed.

The method for manufacturing the semiconductor light emitting device of the present invention comprises the steps of (a)
Providing a semiconductor layer to form a light-emitting layer on a wafer-like substrate; (b) attaching the wafer-like substrate to a resin film; and (c) cutting the wafer-like substrate into chips. A step of separating each chip by extending a resin film, and (d) a step of filling an insulator that transmits light emitted by the chip between the separated chips,
(E) providing a metal film for an electrode on the back surface of the substrate and the surface of the laminated semiconductor layer, and (f) separating the chips by cutting the filled insulator portion. I have. The electrode metal film can be provided after the step (a) or can be provided after the step (d) of filling an insulator.

[0015]

Next, a semiconductor light emitting device of the present invention and a method of manufacturing the same will be described with reference to the drawings.

FIG. 1 is a perspective view of an LED chip according to an embodiment of the present invention, and FIG.
The structure is as shown in (a) and (b). That is, for example, a semiconductor substrate 1 made of n-type GaAs
A semiconductor layer 2 made of, for example, p-type GaAs, for forming a light emitting layer made of a pn junction, is laminated thereon, and a light emitting layer forming portion 12 is formed. This light emitting layer forming part 12
A coating layer 3 made of a light-transmissive insulator is provided on the outer periphery of the LED, and electrodes 4 and 5 are provided on the back surface of the semiconductor substrate 1 and the front surface side of the light emitting layer forming portion 12, respectively.
A chip 10 is configured.

The light emitting layer forming section 12 forms a pn junction by providing a semiconductor layer 2 having a conductivity type different from the conductivity type of the semiconductor substrate 1 on the semiconductor substrate 1 by epitaxial growth or diffusion, as in this example. A pn junction is formed by further providing an n-type layer and a p-type layer on a semiconductor substrate by epitaxial growth or the like, or a semiconductor laminated portion in which an active layer is sandwiched between both n-type and p-type cladding layers on the substrate. It can be formed, for example, by forming a double hetero junction structure.

The substrate 1 is preferably used because a semiconductor substrate can be used to directly electrically connect an electrode on the back side thereof. However, an insulating substrate may be provided by providing a contact hole in the substrate. If an electrode is provided on the back surface side, it can be used. For example, a gallium nitride-based compound semiconductor layer is laminated on a sapphire substrate to form an LE.
Even in the case of a blue LED chip forming a D chip, one electrode may be provided via a contact hole on the back surface side of the substrate.

The coating layer 3 is made of, for example, an insulating transparent resin such as an epoxy resin which does not absorb light emitted from the light emitting layer forming portion 12 or a low melting point glass. Coated. That is, FIG.
When the LED chip shown in (1) is bonded sideways on the mounting substrate, the p-type layer of the light emitting layer forming portion and the n-type
This is to protect the shape layer from being short-circuited. The covering layer 3 is made of a material that transmits light in order to prevent short-circuiting of the light emitting layer forming portion 12 and to use light emitted from the side surface of the LED chip as light to be extracted outside. As a material having such an electrical insulation property and transmitting the emitted light, in addition to the transparent epoxy resin described above, a resin material such as a diffusion epoxy resin and a fluorine-based resin, and a glass material such as a low-melting glass. For example, a light-transmitting insulator which can be solidified after filling can be used.

The electrodes 4 and 5 are made of a material which can easily obtain an ohmic contact with the semiconductor layer used, for example, Au or Al on GaAs by vacuum deposition or the like.
The electrodes 4 and 5 may be provided so as to cover an end portion of the coating layer 3 as shown in FIG. 1, or may be provided so that the coating layer 3 covers a lateral side of the electrode. . That is,
After laminating the semiconductor layer on the substrate, electrodes may be provided on the front surface and the rear surface of the substrate, and then cut and separated into chips to form the coating layer 3, or the semiconductor layers may be laminated and cut and separated into chips. Then, the electrodes 4 and 5 may be provided after forming the coating layer 3.

The LED chip 10 shown in FIGS. 1A and 1B is formed in a rectangular parallelepiped shape in which a light emitting layer (pn junction surface or active layer) has a rectangular outer shape. In order to form the LED chip 10 having a rectangular parallelepiped shape, in the state of a wafer on which semiconductor layers forming a light emitting layer are stacked, FIG.
As shown in (c), the cut line formed by dicing is formed by changing the distance between the vertical and horizontal lines. The rectangular parallelepiped LED chip 10 has, for example, a narrow width dimension H of about 0.17 to 0.2 mm and a wide width dimension of about 0.4 to 0.55 mm. Similarly, it is formed to have a thickness of about 0.2 to 0.3 mm.
That is, even if one side of the rectangular shape of the light emitting layer outer shape is made smaller, the other side is made larger, whereby the area of the pn junction surface can be made constant. As a result, p serving as a light emitting layer
The area of the n-junction surface can be made approximately equal to that of the conventional cubic shape, and the same amount of light can be emitted for the same current (input).

The chip type light emitting element formed by using the LED chip 10 has a structure as shown in FIG. 2, for example, which shows a sectional view and a plan view with the package removed. That is, the terminal electrodes 22 and 23 are provided on both end surfaces of the substrate 21 over the back surface side of the substrate 21, and the pair of electrodes 4 and 5 of the LED chip 10 are turned sideways so as to oppose in the horizontal direction, and The electrodes 4 and 5 are directly bonded to the terminal electrodes 22 and 23 by a conductive adhesive 26 made of solder paste, silver paste, or the like, respectively. Then, the periphery is covered with a package 25 made of epoxy resin or the like. The substrate 21 is made of, for example, an insulating substrate such as a BT resin in which a heat-resistant BT resin is impregnated in a glass cloth. .8mm x 1.6
mm, and the thickness is about 0.15 to 0.2 mm. This substrate is formed by forming a large number of elements in a matrix on a large substrate of about 10 cm × 5 cm at the manufacturing stage, and finally cutting the chips into chip elements. By using the above-mentioned LED chip 10,
An ultra-thin light-emitting element with a total chip-type light-emitting element thickness of 0.5 mm or less can be obtained.

Next, a method of manufacturing the semiconductor light emitting device shown in FIG. 1 will be described with reference to FIG. First, as shown in FIG. 3A, a semiconductor layer is laminated on a wafer-like substrate to form a light emitting layer forming portion, and the back surface of the wafer 13 is adhered to an expand tape 31 to attach each chip. Dicing to cut. S1 is a dicing line. At this time, as described above, vertical and horizontal dicing is performed so that the planar shape becomes rectangular by changing the vertical and horizontal widths.

Next, as shown in FIG. 3 (b), each of the cut chips 10a is separated by extending the expand tape 31, and a gap is provided between the chips 10a. Then, the insulating transparent resin 3
And cure. Thereafter, an electrode material is formed on the front surface and the back surface of the substrate (by peeling the expanded tape) by vacuum evaporation or the like to form an electrode film 5a, and the solidified chip 10a solidified by the insulating transparent resin 3 is re-used. Affix to another expanding tape 35. And FIG.
As shown by a dicing line S2 in FIG. 3C, the above-mentioned injected and cured insulating transparent resin portion 3 is diced,
Each chip 10 is cut and separated. As a result, an LED chip 10 having a structure as shown in FIG. 1 is obtained.

According to the present invention, since the periphery of the semiconductor laminated portion to be laminated is covered with the covering layer made of a light-transmitting insulating material and electrodes are provided at both ends thereof, the LED chip is turned sideways. It can be mounted on a substrate or the like, and a pair of electrodes can be directly bonded to a connection portion of the substrate with a conductive material. In addition, since the coating layer is provided around the light emitting layer forming portion, there is no danger that the semiconductor layer forming the light emitting layer will be short-circuited even if it is laid down on the substrate. For this reason, by dicing the wafer into chips so that the shape of the LED chip becomes a rectangular parallelepiped, the wide surface can be mounted so as to be parallel to the substrate, and light can be extracted from the wide surface. As a result, a thin, high-output semiconductor light-emitting element that can extract light from a wide area that is low in height and does not block light by electrodes or the like is obtained.

Further, according to the LED chip of the present invention,
Since there is no need for wire bonding and it can be directly connected by conductive paste or solder, for example, when arranging LED chips in a matrix to form a dot matrix display device, as shown in FIG.
The LED chip 10 is mounted on the mount substrate 36 provided with the wiring.
Are directly connected by the conductive adhesive 37, so that the interval t between the chips can be made 1 mm or less, and the conventional 2 m
The limit of about m can be reduced to half or less. As a result, a highly accurate display device can be obtained.

The structure of the LED chip 10 is not limited to the pn junction structure described above, but may be a structure in which an active layer is sandwiched between a p-type layer and an n-type layer. Also, the semiconductor material may be made of Al according to the intended emission wavelength.
A GaInP-based compound semiconductor, an AlGaAs-based compound semiconductor, GaP, a gallium nitride-based compound semiconductor, or the like is used, and is not limited to these materials.

In the above-described example, the electrodes are formed on both sides after the semiconductor wafer is cut and separated, and the gap is filled with a transparent resin, and then the electrodes are formed on both sides after the semiconductor layers are laminated. In this state, it may be attached to an expand tape in this state, a gap may be provided between the chips, and the transparent resin may be injected into the gap. In addition, including the above example,
When a translucent insulator such as a transparent resin is injected into the gap between the chips, a tape such as an expand tape is also adhered to the upper surface of the wafer. This is preferable because it does not easily adhere to the upper surface of the substrate.

[0029]

According to the present invention, since the coating layer made of a transparent insulating material is provided around the light emitting layer forming portion of the LED chip, the light emitting layer forming portion can be formed by a simple assembling method. Without causing problems such as short circuit
The electrodes can be directly connected by a conductive adhesive or the like by mounting the ED chip horizontally. As a result, a very thin and small light-emitting element can be obtained, and a thin and high-definition image can be obtained even with a dot matrix display device using an LED chip.

[Brief description of the drawings]

FIG. 1 shows an LED according to an embodiment of the semiconductor light emitting device of the present invention.
It is explanatory drawing of the perspective and cross section of a chip.

FIG. 2 is an explanatory view of a cross section and a plane of a chip type light emitting device using the LED chip of FIG. 1;

FIG. 3 is a diagram illustrating a manufacturing process of the LED chip of FIG. 1;

FIG. 4 is an explanatory diagram when the LED chip of FIG. 1 is used for a dot matrix.

FIG. 5 is an explanatory diagram of a conventional chip-type light emitting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Semiconductor layer 3 Coating layer 4, 5 electrode 10 LED chip 12 Light emitting layer formation part

Claims (4)

[Claims] 1. A substrate, a light-emitting layer forming portion formed by providing a semiconductor layer on the substrate, and a coating layer made of a light-transmitting insulator provided on an outer periphery of the light-emitting layer forming portion. A semiconductor light emitting device comprising a chip including a pair of electrodes provided on a back surface of the substrate and a front surface side of the light emitting layer forming portion, respectively. 2. The semiconductor light emitting device according to claim 1, wherein said substrate and a chip comprising a semiconductor layer provided thereon have a rectangular parallelepiped shape. 3. The chip according to claim 2, wherein the chip is laid on its side so that a pair of electrodes thereof are opposed to each other in a lateral direction, and the chip is mounted on a mount substrate such that the wide surface of the rectangular parallelepiped shape is in contact with the substrate. A semiconductor light emitting device which is disposed and wherein the pair of electrodes are directly bonded to a connection portion of the mount substrate with a conductive material. 4. A step of: (a) providing a semiconductor layer to form a light emitting layer on a wafer-like substrate; (b) attaching the wafer-like substrate to a resin film; (C) a step of separating the chips by cutting the substrate into chips and extending the resin film; (d) a step of filling an insulator that transmits light emitted by the chips between the separated chips; A) providing a metal film for an electrode on the back surface of the substrate and the surface of the laminated semiconductor layer; and (f) separating the filled insulator portion into chips by cutting the filled insulator portion. Manufacturing method.