JPH08130326A - Coupling method for semiconductor crystal using light transmitting conductive thin film - Google Patents

Abstract

PURPOSE: To allow a light-emitting diode to have a high light emission efficiency by placing one light transmission conductive thin film between a semiconductor crystal and a crystal that contains another semiconductor element as an adhesive between them and utilizing it for connecting the crystals. CONSTITUTION: First, a substrate is subjected to corrosion elimination in advance selectively by a general corrosion technique. A new substrate is a GaP transparent substrate 51 that is magnetized positive similarly and the surface is plated by a one-layer thin ITO light transmission thin film 52. Further, after the double hetero of it and an elimination substrate are pinched firmly, it is heated at 500 deg.C or less for approximately one hour, thus completing a crystal junction and hence enclosing one positive conductive GaP transparent substrate 51, one ITO light transmission thin film 52, one positive conductive AlGaAs bottom layer 53, one active AlGaAs middle layer 54 without any impurity, and one negative conductive AlGaAs upper layer 55.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor crystal bonding method applied to a kind of light transmitting conductive thin film.

[0002]

2. Description of the Related Art In the area of light emitting diodes, a transparent substrate is generally used as a method of increasing the luminous intensity of the light emitting diode. Taking a 600 nm aluminum gallium arsenide (AlGaAs) red light emitting diode as an example,
The structure of this type of light emitting diode can be roughly divided into three types. The diode structure in FIG. 1 uses positive conductive gallium arsenide (GaAs) as the monohetero of the substrate 11. The monoheterostructure is a single layer of AlG with positive conductivity.
An aAs layer is grown, and a further negatively conductive AlGaAs layer 13 is grown. The luminous intensity of this type of light emitting diode is 500 to 800 mcd.

The light emitting diode shown in FIG. 2 has a double hetero structure. The double heterostructure has one positive conductive A
1 GaAs bottom layer 22, one impurity-free active Al
GaAs middle layer 23 and one negative conductive AlGaAs
s upper layer 24. The substrate is a GaAs layer 21 having a positive conductivity. The luminous intensity of a light emitting diode of this kind is about 1.5 cd.

The structure of the light emitting diode in FIG. 3 is similar to that of FIG.
1. Active AlGaAs middle layer 3 not containing one impurity
2 and one negative conductive AlGaAs upper layer 31. However, the substrate is AlGaAs having a positive conductivity.
Instead of the s substrate 31. The luminous intensity of light emission of this type of diode reaches about 3 cd, and the luminous intensity of the light emitting diode in the structure shown in FIG. 3 is about twice that of the structure in FIG. The main cause is the adoption of a transparent substrate,
This is because the light generated by the light emitting diode is not absorbed when traveling in the direction of the transparent substrate.

[0005] In the structure of the conventional light emitting diode shown in the above figures, each semiconductor layer is grown by a liquid crystal method, and the diode structure in FIG. 3 has the best luminous efficiency. However, it is very difficult to grow very thick AlGaAs substrates, which makes the production of this type of diode a major challenge for semiconductor manufacturers.

High efficiency other color range light emitting diodes, eg green to red range (560-630 nm)
High brightness aluminum gallium indium phosphide (AlG
In the production of an (aInP) light emitting diode, as shown in FIG. 4, this traditional double hetero is composed of one negatively conductive AlGaInP bottom layer 43, one impurity-free active AlGaInP layer 44, and a positive An AlGaInP upper layer 45 having conductivity is included. Electrode contact end 4
In order to increase the diffusion of the conduction current from 7 and 41, a further positive conductive thick window layer 46 is grown on the double hetero-AlGaInP upper layer 45.

[0007] In the current AlGaInP diode, gallium arsenide (GaAs) having a negative conductivity is generally used as a substrate. However, most of the light emitted to the substrate is absorbed by the opaque substrate in most places, and the luminous efficiency of the diode is limited. F. of the United States HP
A. In an improved diode, proposed by Kish et al., Which eroded GaAs and combined it with a transparent, similarly negatively conductive gallium phosphide (GaP) substrate, the crystal bonding technique used therein was previously described by the United States. Z. of Lincoln Laboratory, Mass. L. It is an extension of the research by Liau et al. Although this type of improved diode has a relatively good luminous intensity, it has two disadvantages. One drawback is that crystal bonding must proceed at fairly high temperatures, generally above 830 ° C. The other is that the crystal curvature or rupture is easily caused on the bonding surface of GaP and AlGaInP due to the mismatch of lattice constants.

[0008]

SUMMARY OF THE INVENTION The present invention aims at providing a kind of new crystal bonding technique, thereby overcoming the difficulties and disadvantages of the prior art, and the bonding technique in the present invention is transparent. An object of the present invention is to use a substrate in place of an opaque substrate so that a light-emitting diode to be produced has high luminous efficiency.

[0009]

SUMMARY OF THE INVENTION A method for bonding a semiconductor crystal to a light-transmitting conductive thin film according to the present invention includes the following steps: a. Providing a first crystal including one semiconductor device; b. Providing a second semiconductor substrate; c. Forming a light-transmitting conductive thin film for forming one light-transmitting conductive thin film on the second semiconductor substrate; d. Sandwiching the second semiconductor substrate and the first crystal tightly so that the light-transmitting conductive thin film intervenes between the second semiconductor substrate and the first crystal; e. The two pieces of crystal sandwiched tightly are heated at high temperature for one step, and the crystals are bonded together.

Further, the transparent conductive thin film is made of a material such as iodine tin oxide (ITO) or cadmium tin oxide (CTO).

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a semiconductor crystal bonding technique, in which one translucent conductive thin film is placed between a semiconductor crystal and another crystal including a semiconductor element, and an adhesive is used therebetween to bond the crystals. Use for This conjugation technique involves first eroding the substrate of the structure containing the semiconductor element, taking another one of the same conductive substrate, plating one light-transmitting conductive thin film, and forming a crystal of the structure containing the semiconductor element. The substrate is tightly sandwiched and heated in a high-temperature furnace for a certain time to bond the substrates. The transparent conductive thin film substrate having the above-described transparent conductive thin film plated thereon is, for example, a transparent substrate, which enhances the luminous efficiency of the diode and adds the transparent conductive thin film so that the transparent substrate can be bonded at a relatively low temperature. To The thin film layer is also provided as a buffer layer with different crystal lattice constants between the bonded crystals, improving the structure of the crystal bonding interface.

[0012]

The present invention provides a kind of crystal bonding technique to improve the luminous efficiency of the conventional light emitting diode shown in FIG. 2, the main purpose of which is to change an opaque semiconductor substrate into a transparent substrate. It is in. In order to bond the substrates easily as well as to buffer the interface of different crystal lattices between the substrate and the double hetero, a layer of transparent conductive thin film is plated on the substrates to be bonded, which serves as a buffer layer.

[0013] The technique of the present invention provides a kind of simple and efficient production method, thereby producing a light emitting diode having high luminous efficiency.

One piece of a negative-conductivity-type GaP transparent substrate plated with an ITO translucent thin film and another piece of a negative-conductivity-type GaP substrate are heated at 500 ° C. for a certain period of time to be bonded to each other. As shown in FIG. 6, the substrate of this bond has a very good current-voltage linear response. FIG. 7 is a current-voltage linear reaction characteristic diagram of another combined substrate,
This bonded substrate is manufactured by heat bonding at a temperature of 700 ° C. for a certain period of time. Its current and voltage also have a very good linear response. It should be noted that the light-transmitting conductive thin film at the bonding interface must have good light-transmitting and conductive properties, and other materials having similar properties include cadmium tin oxide (CTO: Cadmium-Tin-
Oxide) thin film can provide the same effect. The luminous intensity of the light emitting diode can be increased by using this one substrate bonding technique.

The emission intensity of the light emitting diode manufactured according to the present invention is approximately the same as that of the conventional light emitting diode shown in FIG. However, there is no difficulty in growing a very thick AlGaAs substrate.

As shown in FIG. 2, the double hetero in the conventional light emitting diode has one positive conductive substrate, on which a layer of positive conductive AlGaAs is first grown,
Open, active AlGaAs without further impurities on it
s layer is grown and finally one negative conductive AlGaAs
To grow.

According to the present invention, as shown in FIG. 5, as in the case of the conventional diode, the substrate is first selectively corroded and removed by using a general corrosive technique. The new substrate is also a GaP transparent substrate 51 having a positive conductivity, and the surface thereof is plated with a thinner ITO light transmitting thin film 52. After tightly sandwiching the double hetero with the substrate to be removed, it is placed in a high temperature furnace of nitrogen gas or hydrogen gas at a temperature of 500 ° C. for about 1 hour.
Heat for an hour to complete crystal bonding. Thus, the structure of the present invention is a single GaP transparent substrate 5 having a positive conductivity.
1. One ITO translucent thin film 52, one positive conductive AlGaAs bottom layer 53, one active impurity-free A
lGaAs middle layer 54, and one negatively conductive A
Includes 1 GaAs overlayer 55.

Compared to the existing crystal bonding technology, the technology of the present invention can bond at a relatively low temperature in a relatively short time. Z. L. The technique studied by Liau generally proceeds at a temperature of 830 ° C. and takes about 2 hours. In the present invention, after one layer of the light-transmitting conductive thin film is added, the product can be bonded at about 500 ° C. and completed in only one hour, the diffusion of impurities or the supercrystal lattice and the quantum well structure layer are completed. Inter-diffusion of element and interlayer element can be avoided, and deterioration of the element is prevented. The technique of the present invention can be easily manufactured and can respond to a difference in crystal structure between different materials using a light-transmitting conductive thin film as a buffer layer. Because the light-transmitting conductive thin film itself is an amorphous layer, the different crystal lattice constants and thermal expansion coefficients of different materials are buffered, and the crystal after bonding is also less likely to bend. can do.

The technique of the present invention similarly applies to AlGa in FIG.
It can be applied to the conventional light emitting diode containing InP. First, the negative conductive GaAs substrate is corroded and removed, and then the negative conductive GaP substrate having the ITO light-transmitting thin film plated is bonded instead. Then, the light emitting diode shown in FIG. 8 is completed. Similar bonding techniques can be used for different double hetero materials. The structure of FIG. 8 is, from bottom to top, electrode contact end 81, one negatively conductive Ga.
P substrate 82, one ITO transparent conductive thin film 83, one negative conductive AlGaInP bottom layer 84, one impurity-free active AlGaInP layer 85, one positive conductive AlGaInP upper layer 86, and one positive conductive AlGaInP upper layer 86. Conductive window layer 87, and another electrode contact end 88.

[0020]

According to the technique of the present invention, the substrate to be grown to double hetero is first removed by the traditional corrosion technique, and then,
Plating a layer of translucent conductive thin film on a new transparent substrate,
Furthermore, after heating the new double hetero substrate tightly and integrally in a high-temperature furnace for one step, the crystals are bonded to each other to complete a highly efficient light emitting diode. In the present invention, the light-transmitting conductive thin film has very good conductivity and light-transmitting properties, and transmits most of blue to red light. Further, since this thin film is an amorphous layer, it has a buffering effect due to the difference in lattice, and therefore serves as a buffering layer for bonding different crystalline structures between two different materials to each other. The crystal bonding technique in the present invention proceeds at relatively low temperatures, which makes production and manufacture relatively easy. By adding one buffer layer thin film, the structure of the diode is further strengthened, and at the same time, effective luminous efficiency is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conventional light emitting diode having an AlGaAs monohetero.

FIG. 2 is a cross-sectional view of a conventional light emitting diode having an AlGaAs double heterostructure.

FIG. 3 shows a conventional AlGaAs double heterostructure and AlGa
It is sectional drawing of the light emitting diode which has an As substrate.

FIG. 4 is a cross-sectional view of a conventional light emitting diode having an AlGaInP double heterostructure and a coupled GaP substrate.

FIG. 5 shows a light emitting diode of the present invention, wherein one AlG
FIG. 4 is a cross-sectional view of a coupling substrate GaP having an aAs double heterostructure and a single ITO thin film.

FIG. 6 shows that two GaP substrate pieces are I
FIG. 4 is a current-voltage characteristic diagram after bonding at 50 ° C. with a TO thin film and processing for a predetermined time.

FIG. 7 shows that two GaP substrate pieces are I
FIG. 4 is a current-voltage characteristic diagram after bonding at 70 ° C. with a TO thin film and processing for a predetermined time.

FIG. 8 shows a light emitting diode according to the present invention, wherein one AlGaI
It is sectional drawing of the coupling substrate GaP which has a nP double hetero and one layer of ITO thin film.

[Explanation of symbols]

 51: Positive conductive GaP transparent substrate 52: ITO translucent thin film 53: Positive conductive AlGaAs bottom layer 54: Active AlGaAs middle layer 55: Negative conductivity AlGaAs upper layer 81 with electrode contact end 82 Negative conductive GaP substrate 83 ITO light transmitting conductive thin film 84 Negative conductive AlGaInP bottom layer 85 Active AlGaInP layer 86 ... positive conductive AlGaInP upper layer 87 ... positive conductive window layer 88 ... electrode contact end

Claims (2)

[Claims] 1. A method comprising: a. Providing a first crystal including one semiconductor device; b. Providing a second semiconductor substrate; c. Forming a light-transmitting conductive thin film for forming one light-transmitting conductive thin film on the second semiconductor substrate; d. Sandwiching the second semiconductor substrate and the first crystal tightly so that the light-transmitting conductive thin film intervenes between the second semiconductor substrate and the first crystal; e. The two pieces of tightly sandwiched crystals are heated at a high temperature for one step, thereby bonding the crystals. A method of bonding a semiconductor crystal using a light transmitting conductive thin film, including the above steps. 2. The light-transmitting conductive thin film comprises an iodine tin oxide (I)
2. The method according to claim 1, wherein the material is a material such as TO) or cadmium tin oxide (CTO).