CN101159301A - A semiconductor light emitting device and its manufacturing method - Google Patents

Abstract

The invention discloses a semiconductor light-emitting device, which comprises a substrate and a semiconductor epitaxial stack laminated on the substrate. The semiconductor epitaxial stack includes an N-type layer, a light-emitting layer and a P-type layer in sequence from bottom to top. An electrode is provided on the lower surface of the substrate. A P-type electrode is provided on the upper surface of the P-type layer, wherein a part of the P-type layer is etched to the N-type layer, and an N-type electrode is provided. The N-type electrode is connected, and the other end is in electrical contact with the substrate; the conductor is composed of a columnar through hole and a conductive substance filled in the through hole; the conductor can also extend to the bottom of the substrate and connect with the bottom surface of the substrate The electrodes are connected. The invention can effectively reduce the operating voltage of the semiconductor light emitting device and increase the output power of the semiconductor light emitting device. In addition, the invention also discloses a manufacturing method of the semiconductor light emitting device.

Description

A semiconductor light emitting device and its manufacturing method

technical field

The invention relates to a semiconductor light emitting device and a manufacturing method thereof.

Background technique

III-V nitride semiconductor materials are widely used in violet, blue, green and white light-emitting diodes, violet lasers for high-density optical storage, ultraviolet light detectors, and high-power high-frequency electronic devices. However, due to the lack of suitable substrates, current high-quality GaN-based material films are usually grown on sapphire or SiC substrates, but both substrates are relatively expensive, especially SiC, and are relatively small in size. In addition, sapphire has the disadvantages of extremely high hardness, non-conductivity, and poor thermal conductivity.

In order to overcome the above shortcomings, people have been continuously exploring the growth of GaN using Si as a substrate. It is expected that the heteroepitaxial growth of III-nitride light-emitting devices on Si substrates has obvious technical advantages in terms of cost reduction. The advantage of using Si as a GaN-based light-emitting diode (LED) substrate is that the manufacturing cost of the LED will be greatly reduced, not only because the price of the Si substrate itself is much cheaper than the currently used sapphire and SiC substrates, but also can be used Sapphire and SiC substrates have larger Si substrates to increase the utilization of metal-organic chemical vapor deposition (MOCVD) equipment, thereby increasing the yield of chips. Si and SiC substrates are also conductive substrates. The electrodes can be drawn out from the top and bottom of the chip to form a vertical conductive structure, which is different from the lateral structure of the insulating sapphire substrate where the electrodes must be drawn out from the same side. This can not only effectively utilize The chip area can also simplify the packaging process. At the same time, LED chips can be manufactured using the mature technology in Si integrated circuit processing, which saves the cost of chip production.

However, compared to sapphire and SiC, it is more difficult to grow GaN on Si substrates because of the larger thermal and lattice mismatch between Si and GaN materials. The difference in thermal expansion coefficient between Si and GaN will cause cracks in the GaN film, and the large lattice mismatch will cause high dislocation density in the GaN epitaxial layer. Although the manufacturing technology of GaN-based LEDs on Si substrates has achieved many exciting results, there are still defects of high operating voltage and low output power. On the one hand, there is a large gap between the thermal expansion coefficients of Si and GaN. The GaN film is cracked due to the combination, and the difference in lattice constant will cause high dislocation density in the GaN epitaxial layer. The Si substrate also has serious light absorption problems. In order to solve the problems of cracking, lattice mismatch and light absorption, people usually Introduce various buffer layers (such as AlN/GaN) and insertion layers (such as the DBR reflective layer introduced to solve the light absorption problem), but the introduction of these foreign layers will increase the operating voltage of the device; on the other hand, in the GaN-based LED structure There is a large energy band discontinuity between Si and GaN, which increases the turn-on voltage, and poor crystal integrity results in low doping efficiency of P-type GaN, resulting in increased series resistance. Solving the problem of high operating voltage of GaN-based LED chips on Si substrates is the key to the practical application of GaN-based LEDs on Si substrates.

Contents of the invention

The object of the present invention is to provide a semiconductor light-emitting device capable of effectively reducing the operating voltage and a manufacturing method thereof.

In order to achieve the above object, the present invention adopts the following technical solutions:

A semiconductor light-emitting device, which includes a substrate and a semiconductor epitaxial stack stacked on the substrate. The semiconductor epitaxial stack includes an N-type layer, a light-emitting layer and a P-type layer in sequence from bottom to top. An electrode is provided on the lower surface of the substrate. A P-type electrode is provided on the upper surface of the P-type layer, wherein a part of the P-type layer is etched to the N-type layer, and an N-type electrode is provided. The N-type electrodes are connected, and the other end is in electrical contact with the substrate.

The conductor is composed of a columnar through hole and a conductive material filled in the through hole.

The through hole is a columnar through hole with a circular or square cross section.

The conductor can also extend to the bottom of the substrate and be connected to the electrodes on the lower surface of the substrate.

The size and depth of the semiconductor epitaxial stack or the through hole can be specifically set according to actual operating conditions.

In order to solve the problem of cracks in the semiconductor epitaxial stack or lattice mismatch with the substrate, a buffer layer is also provided between the semiconductor epitaxial stack and the substrate.

In order to solve the light absorption problem of the substrate, a DBR reflective layer is also arranged between the buffer layer and the semiconductor epitaxial stack.

The above substrate is formed of Si-based material, and the semiconductor epitaxial stack and the DBR reflective layer are all made of aluminum gallium indium nitrogen (In _x Ga _y Al _1-xy N, 0<=x<=1, 0<=y<=1) material formed.

In order to make the filled conductive substance fully contact with the N-type layer sidewall and Si substrate, the filling substance of the columnar through hole can be any conductive material such as various metals or alloys or conductive resins, and can also be any combination of the above materials .

In addition, the present invention also provides a method for manufacturing a semiconductor light-emitting device, the steps of which include: depositing a semiconductor epitaxial stack on a Si substrate, and the semiconductor epitaxial stack includes an N-type layer, a light-emitting layer, and a P layer from bottom to top. Type layer; Part of the P-type layer is etched to the N-type layer by dry etching, and a region is etched in the exposed N-type layer, and a conductor is formed in the region, and one end of the conductor is exposed on the surface of the N-type layer. The other end is in electrical contact with the Si substrate; using a photolithography process, define an N-type electrode region on the top of the conductor, and evaporate an N-type electrode on this region; define a P-type electrode region on the upper surface of the P-type layer, and A P-type electrode is formed in this region, and a metal layer is vapor-deposited on the lower surface of the Si substrate to form an electrode.

The conductor can be formed by etching a through hole in the N-type layer and filling the conductive substance in the through hole.

The through hole can also be etched to the inside of the Si substrate or to the bottom of the Si substrate, and be in contact with the electrode formed on the lower surface of the substrate.

The columnar through hole provided by the semiconductor light-emitting device and its manufacturing method of the present invention runs through the entire semiconductor epitaxial stack, and is partially or completely etched through the substrate. After the columnar through hole is filled with a conductive substance, the N-type layer passes through the conductive substance and The Si substrate or the electrode contact at the lower end of the Si substrate. When working, most of the current flowing through the P-type electrode will flow to the Si substrate through the low-resistance conductive material after passing through the N-type layer, and a small part will flow directly to the Si substrate through the N-type layer. On the one hand, the electrical interconnection between the N-type layer and the Si substrate reduces the excessive operating voltage introduced by the traditional Si substrate semiconductor light-emitting device chip due to the additional layer and the Si and semiconductor epitaxial stack barrier; on the other hand, compared to For semiconductor light-emitting device chips with sapphire substrates, since part of the current flows directly to the Si substrate through the N-type layer, the current blocking effect in the insulating sapphire substrate chips is partially eliminated.

Therefore, the invention can significantly reduce the operating voltage of the semiconductor light-emitting device and improve the current spreading effect, while the good thermal conductivity of the Si substrate can improve the thermal performance of the device. At the same time, the process is simple and easy, and will not increase excessive chip manufacturing costs.

Description of drawings

FIG. 1 is a schematic structural view of a semiconductor light emitting device according to Embodiment 1 of the present invention.

Fig. 2 is a schematic structural view of a semiconductor light emitting device according to Embodiment 2 of the present invention.

Fig. 3 is a schematic structural view of a semiconductor light emitting device according to Embodiment 3 of the present invention.

In the above figure, 1 is the substrate, 3 is the conductive material, 4 is the P-type layer, 5 is the light-emitting layer, 6 is the N-type layer, 7 is the buffer layer, 8 is the transparent conductive film, 9 is the P-type electrode, 10 is the The electrode on the lower surface of the substrate, 11 is the N-type electrode on the top of the through hole, 12 is the DBR reflective layer, and 13 is the columnar through hole.

Detailed ways

Example 1

With reference to Fig. 1, a kind of semiconductor light-emitting device, it comprises substrate 1 and the semiconductor epitaxial laminated layer stacked on substrate 1, and this semiconductor epitaxial laminated layer comprises N-type layer 6, light-emitting layer 5 and P-type layer successively from bottom to top. Layer 4, a layer of transparent conductive film 8 is formed on the upper surface of the P-type layer 4, a P-type electrode 9 is arranged on the transparent conductive film 8, and an electrode 10 is arranged on the lower surface of the substrate 1, wherein the N-type layer 6 A conductor is provided inside, one end of which exposes the N-type layer 6 , and an N-type electrode 11 is provided, the other end of which is in electrical contact with the substrate 1 .

The conductor is composed of a columnar through hole 13 and a conductive substance 3 filled in the through hole 13 . The through hole 13 is a columnar through hole with a circular or square cross section.

In order to make the filled conductive substance 3 fully contact with the side wall of the N-type layer 6 and the substrate 1, the conductive substance 3 filled in the columnar through hole 13 can be various metals or alloys, such as Au, Ag, Al, Ti, Ni, Cu, ITO, Pt, AuSb, etc. can also be any conductive material such as conductive resin, and can also be any combination of the above materials. In order to prevent the short circuit of the device, a certain space must be left between the conductive substance 3 and the P-type layer 4 .

The substrate 1 is formed of Si-based material, and the semiconductor epitaxial stack is formed of aluminum gallium indium nitride (In _x Ga _y Al _1-xy N, 0<=x<=1, 0<=y<=1) material.

In order to solve the problem of cracks in the semiconductor epitaxial stack or lattice mismatch with the substrate 1 , a buffer layer 7 is also provided between the semiconductor epitaxial stack and the substrate 1 .

The manufacturing method of the semiconductor light emitting device comprises the following steps:

Clean the Si substrate 1 first, put it into metal-organic chemical vapor deposition equipment, and deposit a buffer layer 7 and a semiconductor epitaxial stack structure on the Si substrate 1 in sequence. The semiconductor epitaxial stack includes an N-type layer 6, multi-quantum Well light-emitting layer 5 and P-type layer 4.

After the deposition of the semiconductor epitaxial stack is completed, the region shown in FIG. 1 is etched by dry etching to form a region, and a conductor is formed in the region, and one end of the conductor exposes the surface of the N-type layer 6. The other end is in electrical contact with Si substrate 1 .

The conductor is formed by the columnar through hole 13 formed by etching in the N-type layer 6 and the conductive substance 3 filled in the through hole 13 . The columnar through-hole 13 passes through the semiconductor epitaxial stack until it contacts the Si substrate 1, and then the peripheral area of the through-hole 13 is etched to the N-type layer 6 to expose the surface of the N-type layer 6, and magnetron sputtering or electroplating is used to The process deposits a conductive substance 3 in the via hole 13 to fill the via hole 13 .

Using a photolithography process, define an N-type electrode area on the N-type layer mesa where the top of the through hole 13 is located, evaporate the N-type electrode 11, and anneal to form an ohmic contact, so that the N-type layer 6 and the Si substrate 1 are interconnected through the conductive substance 3 .

Using a photolithography process, define a P-type region on the upper surface of the P-type layer 4, and form a transparent conductive film 8 on the surface of the P-type region; define a P-type electrode region on the transparent conductive film 8, and vapor-deposit on the P-type electrode region A P-type electrode 9 is formed; a metal layer is evaporated on the lower surface of the Si substrate to form an electrode 10 .

The semiconductor epitaxial stack is cut to form independent semiconductor light emitting device chips.

In the present embodiment, the transparent conductive film 8 can adopt nickel-gold alloy oxide (Oxidzed-Ni/Au), indium tin oxide (ITO), zinc aluminum oxide (AZO), zinc oxide, and their compositions (such as Ni/ AZO, NiO/AZO, Ni/ZnO, NiO/ZnO, etc.).

Among them, Ni/Au is evaporated by electron beam evaporation (E-gun Evaporator), and the thickness of the evaporation is 50/100 Ȧ; Heat treatment at 550° C. for 5 minutes to form Ni/Au oxides.

ITO is deposited using an electron beam evaporation machine (E-gun Evaporator), and the thickness of the deposition is 2000-10000 Ȧ; after ITO is deposited, it is then heat-treated at 600 ° C for 5 minutes in an RTA system in a nitrogen environment to form ohmic contact.

AZO is deposited using an ion sputtering machine (Sputter), and the deposition thickness is 2500 Ȧ. In order to improve the ohmic contact characteristics between AZO and the P-type layer 4, 50 Ȧ of 50 Ȧ were vapor-deposited on the P-type layer 4 before depositing AZO. Ni, NiOx, and then AZO deposition. After deposition, heat treatment is performed at 800° C. for 1 minute with an RTA system under a nitrogen atmosphere.

Example 2

As shown in Figure 2, this embodiment is similar to Embodiment 1, the difference is that in this embodiment, in order to reduce the internal resistance of the substrate 1, the through hole 13 can be etched through the entire substrate 1 to form a full through hole. , and the conductive substance 3 is filled in the through hole 13, and the N-type layer 6 is directly in electrical contact with the electrode 10 at the lower end of the substrate 1 through the conductive substance 3.

Of course, according to different requirements on the internal resistance of the semiconductor light emitting device in practical applications, the through hole 13 may also partially penetrate the substrate 1 .

Example 3

As shown in Figure 3, this embodiment is similar to Embodiment 1, and the difference is that in this embodiment, in order to improve the light extraction efficiency of the semiconductor light emitting device, aluminum gallium indium nitrogen (InxGayAl1-x -yN, 0<=x<=1, 0<=y<=1) DBR reflective layer 12 of material (typical structure is AlGaN/AlN etc.), at this moment through hole 13 structures need to be etched during dry process Etching passes through the DBR reflective layer 12 and the buffer layer 7 to reach the substrate 1 .

Of course, according to different requirements on the internal resistance of the semiconductor light emitting device in practical applications, the through hole 13 may partially or completely penetrate the substrate 1 by using a method similar to that of Embodiment 2.

Claims (10)

1. A semiconductor light-emitting device, comprising a substrate (1) and a semiconductor epitaxial stack stacked on the substrate (1), the semiconductor epitaxial stack comprising an N-type layer (6), a light-emitting layer from bottom to top (5) and a P-type layer (4), the lower surface of the substrate (1) is provided with an electrode (10), and the upper surface of the P-type layer (4) is provided with a P-type electrode (9), wherein part of the P The N-type layer (4) is etched to the N-type layer (6), and an N-type electrode (11) is provided, which is characterized in that: a conductor is provided in the exposed area of the N-type layer (6), and one end thereof is connected to the N-type layer (6). The type electrode (11) is connected, and the other end is in electrical contact with the substrate (1). 2. The semiconductor light emitting device according to claim 1, characterized in that: the conductor is composed of a columnar through hole (13) and a conductive substance (3) filled in the through hole (13). 3. The semiconductor light emitting device according to claim 2, characterized in that: the through hole (13) is a columnar through hole with a cross section such as a circle or a square. 4. The semiconductor light emitting device according to claim 2, characterized in that: the conductive substance (3) is metal or alloy or conductive resin or any combination thereof. 5. The semiconductor light emitting device according to claim 1, characterized in that the conductor extends to the bottom of the substrate (1) and is connected to the electrode (10) on the lower surface of the substrate (1). 6. The semiconductor light-emitting device according to any one of claims 1 to 5, characterized in that: the substrate (1) is made of Si-based material, and the semiconductor epitaxial stack is made of aluminum gallium indium nitrogen (In _x Ga _y Al _{1 -xy} N, 0<=x<=1, 0<=y<=1) Material formation. 7. The semiconductor light emitting device according to any one of claims 1 to 5, characterized in that: a DBR reflective layer (12) is further arranged between the substrate (1) and the semiconductor epitaxial stack. 8. The semiconductor light emitting device according to claim 7, characterized in that: the DBR reflective layer (12) is made of aluminum gallium indium nitrogen (In _x Ga _y Al _1-xy N, 0<=x<=1, 0<=y<=1) Material formation. 9. A method for manufacturing a semiconductor light emitting device, the steps comprising: a. Depositing a semiconductor epitaxial stack on the Si substrate (1), the semiconductor epitaxial stack includes an N-type layer (6), a light-emitting layer (5) and a P-type layer (4) from bottom to top; b. By dry etching, part of the P-type layer is etched to the N-type layer (6), and a region is etched in the exposed region of the N-type layer (6), and a conductor is formed in this region. One end of the body exposes the surface of the N-type layer (6), and the other end is in electrical contact with the Si substrate (1); c. Using a photolithography process, define an N-type electrode area on the top of the conductor, and evaporate an N-type electrode (11) on this area; d. Define a P-type electrode region on the upper surface of the P-type layer (4), and form a P-type electrode (9) in this region, and evaporate a metal layer on the lower surface of the Si substrate (1) to form an electrode (10) . 10. The manufacturing method of a semiconductor light emitting device according to claim 9, characterized in that: in step b, the conductor is formed by etching the through hole (13) in the exposed area of the N-type layer (6) and A conductive substance (3) filled in a through hole (13) passing through the semiconductor epitaxial stack and in contact with the Si substrate (1) is formed.

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