WO2019127423A1

WO2019127423A1 - Led chip having composite diamond substrate and preparation method therefor

Info

Publication number: WO2019127423A1
Application number: PCT/CN2017/119984
Authority: WO
Inventors: 何宗江; 贾志强
Original assignee: 深圳前海小有技术有限公司; 深圳佑荟半导体有限公司
Priority date: 2017-12-29
Filing date: 2017-12-29
Publication date: 2019-07-04

Abstract

Disclosed are an LED chip having a composite diamond substrate and a preparation method therefor. The LED chip comprises a composite diamond substrate and an LED epitaxy grown thereon, wherein the composite diamond substrate comprises a diamond base, and a diamond buffer layer generated on the diamond base and comprising a diamond transition layer located on the diamond base and a boron-doped diamond thin film layer grown on the diamond transition layer. By forming, on a diamond base, a composite diamond substrate comprising a diamond transition layer and a boron-doped diamond thin film layer, the epitaxy of an LED chip can be grown with high quality on the composite diamond substrate. The shortcoming of poor heat dissipation performance of a common sapphire substrate can be overcome, and the defects such as crystal lattice dislocation during an epitaxy growth process can also be overcome. Furthermore, by forming a patterned graphene layer on the composite diamond substrate, the performance of the prepared LED chip can further be improved.

Description

LED chip with composite diamond substrate and preparation method thereof

Technical field

The present invention relates to the field of semiconductor technology, and more particularly to an LED chip having a composite diamond substrate and a method of fabricating the same.

Background technique

At present, a commonly used LED package structure has a structure as shown in FIG. 1, including a bottom plate and an upper cover plate, in which a chip is placed, and then a sealant is used to form a closed space between the bottom plate and the upper cover plate. Among them, sapphire is generally used as a substrate material, but the sapphire substrate has poor heat dissipation performance, and there is a problem that lattice mismatch causes dislocations or the like when the LED epitaxial growth is performed on the sapphire substrate.

Diamond materials have excellent thermal and mechanical properties and are expected to replace sapphire as a substrate material for LED chips. There are some problems in the direct growth of LED epitaxy on diamond materials. At present, there is not much research on diamond as a substrate. This application studies this and develops an LED chip with a composite diamond substrate and a method for preparing the same.

Summary of the invention

In view of the problem that the sapphire substrate is generally used in the existing LED chip, and the sapphire substrate has poor heat dissipation performance, the present invention provides an LED chip having a composite diamond substrate and a preparation method thereof.

One aspect of the present invention provides an LED chip having a composite diamond substrate, which may include: a composite diamond substrate and an LED epitaxial growth on the composite diamond substrate,

Wherein the composite diamond substrate comprises: a diamond substrate, and a diamond buffer layer formed on the diamond substrate, the diamond buffer layer comprising a diamond transition layer on the diamond substrate and growing on the diamond transition layer Boron doped diamond film layer.

Preferably, the composite diamond substrate further comprises a patterned graphene layer on the boron doped diamond film layer.

Further, the patterned graphene layer has a plurality of concave structures arranged on the graphene layer, and an upper plane between the two adjacent concave structures, the concave structure including a transition from top to bottom a face, a side wall and a lower plane, the side wall extending upward along the lower planar edge and forming a recess together with the lower plane, the transition surface extending obliquely upward along the end of the side wall, one end of the transition surface connecting the The sidewall and the other end are connected to the upper plane, and the lower plane is an upper surface of the boron doped diamond thin film layer.

Another aspect of the present invention provides a method of fabricating an LED chip having a composite diamond substrate, the method comprising the steps of:

Growing a diamond transition layer on the diamond substrate;

Growing a boron doped diamond thin film layer on the diamond transition layer, thereby forming a composite diamond substrate;

LED epitaxy is grown on the composite diamond substrate.

The method may further include growing a patterned graphene layer on the boron doped diamond thin film layer, thereby forming a composite diamond substrate.

Preferably, a diamond transition layer is grown on the <111> face of the diamond substrate.

Preferably, the growth condition of the diamond transition layer on the diamond substrate may be: in the vapor phase growth furnace, methane and hydrogen are introduced in a volume ratio of 0.2-2.3:100, and the temperature of the diamond substrate is adjusted to be in the range of 1100-1180 ° C by adjustment. The reaction gas pressure was 8.5 kPa and the growth time was 0.25-0.45 hours.

Preferably, in the method, the thickness of the diamond transition layer grown may be 0.35-0.4 μm.

Preferably, the growth condition of the boron-doped diamond thin film layer grown on the diamond transition layer may be: introducing methane, hydrogen, and a boron source in a volume ratio of 1:20-30:0.8-1.2 into the vapor phase growth furnace. The hydrogen gas is adjusted to a pressure of 8 kPa to 9 kPa, and the temperature of the diamond transition layer is controlled at 700-900 ° C for 1-3 hours.

Preferably, the source of boron may be trimethyl borate.

Preferably, growing the patterned graphene layer on the boron doped diamond thin film layer may further comprise the following steps:

Depositing a patterned silicon dioxide mesh film on the boron doped diamond thin film layer;

Forming a thin layer of copper within the silica grid;

Passing hydrogen gas and methane as a carbon source to form a graphene layer on the boron-doped diamond thin film layer and the patterned silicon dioxide mesh film at a high temperature;

The patterned silicon dioxide mesh film and the graphene layer thereon are removed, thereby producing a patterned graphene layer.

Further, the patterned graphene layer has a plurality of concave structures arranged on the graphene layer, and the upper adjacent planes are upper planes, and the concave structures include transitions from top to bottom. a face, a side wall and a lower plane, the side wall extending upward along the lower planar edge and forming a recess together with the lower plane, the transition surface extending obliquely upward along the end of the side wall, one end of the transition surface connecting the The sidewall and the other end are connected to the upper plane, and the lower plane is an upper surface of the boron doped diamond thin film layer.

Beneficial effect

The method for preparing an LED chip with a composite diamond substrate disclosed in the present application can form a composite diamond substrate with high quality by forming a composite diamond substrate comprising a diamond transition layer and a boron-doped diamond film layer on a diamond substrate. The epitaxial growth of the LED chip can not only solve the shortcomings of the poor heat dissipation performance of the commonly used sapphire substrate, but also solve the defects such as lattice dislocation during the epitaxial growth process. Further, it can further form a pattern on the composite diamond substrate. The graphene layer can further improve the performance of the prepared LED chip.

DRAWINGS

The above and other objects, features and other advantages of the present invention will become more <RTIgt;

1 is a schematic view of a prior art package structure;

2 is a schematic view of a diamond substrate used in the preparation of an LED chip having a composite diamond substrate according to an embodiment of the present invention;

3 is a schematic view showing the formation of a diamond buffer layer on a diamond substrate in the preparation of an LED chip having a composite diamond substrate according to an embodiment of the present invention;

4 is a schematic view showing the formation of a patterned silicon dioxide mesh film on a diamond buffer layer in the preparation of an LED chip having a composite diamond substrate according to an embodiment of the present invention;

5 is a schematic view showing the formation of a thin layer of copper in a silica grid in the preparation of an LED chip having a composite diamond substrate according to an embodiment of the present invention;

6 is a schematic view showing the formation of a graphene layer on the diamond buffer layer and the patterned silicon dioxide grid film in the preparation of an LED chip having a composite diamond substrate according to an embodiment of the present invention;

7 is a schematic view showing the removal of the patterned silicon dioxide mesh film and the graphene layer thereon in the preparation of an LED chip having a composite diamond substrate according to an embodiment of the present invention;

8 is a schematic view showing growth of an LED epitaxial growth on a composite diamond substrate having a patterned graphene layer in the preparation of an LED chip having a composite diamond substrate according to an embodiment of the present invention;

9 is a schematic structural view of a patterned graphene layer according to an embodiment of the present invention;

Figure 10 is an enlarged view of a concave structure of Figure 9;

Figure 11 is a schematic view showing the structure of particulate silica according to an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the drawings and specific embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a method for preparing an LED chip with a composite diamond substrate and a prepared LED chip with a composite diamond substrate. The LED chip having a composite diamond substrate may include a composite diamond substrate and an LED epitaxial growth on the composite diamond substrate. Wherein the composite diamond substrate comprises: a diamond substrate, and a diamond buffer layer formed on the diamond substrate, the diamond buffer layer comprising a diamond transition layer on the diamond substrate and boron grown on the diamond transition layer Doped diamond film layer. The diamond substrate used in the present invention may be natural diamond or synthetic diamond. Before use, the diamond substrate may be cleaned in advance. A common method is ultrasonic cleaning of the diamond substrate, for example, using a solvent such as acetone or ethanol. Further, it is preferred to grow a diamond transition layer on the <111> face of the diamond substrate. At present, the commonly used sapphire substrate has poor heat dissipation performance, and when it is epitaxially grown on a sapphire substrate, lattice dislocations are easily generated, which affects the quality of the finally formed LED chip, and the composite diamond substrate of the present application can be greatly improved. The heat dissipation performance, and the boron doped diamond film layer is also favorable for the epitaxial growth thereon. In addition, when the boron-doped diamond thin film layer is deposited on the graphene material, the formed graphene layer is more likely to generate an energy gap, thereby facilitating utilization of the excellent characteristics of the graphene material and improving device performance. Preferably, the composite diamond substrate may further comprise a patterned graphene layer on the boron doped diamond thin film layer. The formation of the patterned substrate can further improve the light extraction efficiency of the LED chip, and is also expected to reduce the dislocation density and the like. Preferably, as shown in FIG. 9, the patterned graphene layer 51 has a plurality of concave structures arranged on the graphene layer, and the upper adjacent planes are upper planes, and the concave structures are from above. And the lower portion includes a transition surface, a sidewall and a lower plane, the sidewall extending upward along the lower planar edge and forming a recess together with the lower plane, the transition surface extending obliquely upward along the sidewall end, the transition surface One end is connected to the sidewall, and the other end is connected to the upper plane, and the lower plane is an upper surface of the boron doped diamond thin film layer. Figure 10 shows an enlarged view of a concave structure with an upper plane 124 between each adjacent concave structure, each concave structure comprising a transition surface 122, a side wall 121 and a lower plane 123, said side wall 121 An edge of the lower plane 123 extends upwardly and forms a recess together with the lower plane 123; the transition surface 122 extends obliquely upward along an upper end portion of the sidewall 121, and the transition surface 122 is coupled to the sidewall 121 and the upper plane Between 124. The side wall 121 is in an oblique direction and the angle between the side wall 121 and the lower plane 123 is α, α is between 100° and 120°, and the optimum value is 110°. The angle between the transition surface 122 and the upper plane 124 is β, β is between 120° and 150°, and the optimum value is 140°. By arranging the concave structure as the inclined side wall 121 and providing the transition surface 122 between the inclined side wall 121 and the upper plane 124, when the LED epitaxial growth is grown on the patterned graphene layer, more passes can be made. When the light of the concave structure is emitted to the outside, the incident angle is smaller than the critical angle of total reflection and is emitted to the outside, thereby greatly improving the light extraction efficiency of the LED and improving the light extraction efficiency of the LED chip. Further, the lower plane 123 may have a circular shape, and when the concave structure is viewed from top to bottom, the concave structure is arranged in a hexagonal hole shape or in a circular hole shape.

In order to prepare the LED chip with the composite diamond substrate of the present invention, the following preparation method may be employed, and the method may include the following steps:

Growing a diamond transition layer on the diamond substrate;

LED epitaxy is grown on the composite diamond substrate.

In a preferred embodiment, the diamond transition layer may preferably be grown on the <111> face of the diamond substrate. Further, the diamond substrate may be cleaned in advance. For example, the diamond substrate may be ultrasonically cleaned using a solvent such as acetone or ethanol, and then the transition layer may be grown.

Specifically, the growth condition of the diamond transition layer on the diamond substrate may be: in the vapor phase growth furnace, methane and hydrogen are introduced in a volume ratio of 0.2-2.3:100, and the temperature of the diamond substrate is adjusted in the range of 1100-1180 ° C by adjustment. The reaction gas pressure was 8.5 kPa and the growth time was 0.25-0.45 hours. Preferably, in the method, the thickness of the diamond transition layer grown may be 0.35-0.4 μm. The formation of the diamond transition layer can facilitate the formation of the boron doped diamond film layer, and also facilitate the combination of the boron doped diamond film layer and the diamond substrate.

Preferably, the growth condition of the boron-doped diamond thin film layer grown on the diamond transition layer may be: introducing methane, hydrogen, and a boron source in a volume ratio of 1:20-30:0.8-1.2 into the vapor phase growth furnace. The hydrogen gas is adjusted to a pressure of 8 kPa to 9 kPa, and the temperature of the diamond transition layer is controlled at 700-900 ° C for 1-3 hours. Preferably, the source of boron may be trimethyl borate. With the preferred growth conditions described above, a boron doped diamond film layer having a suitable amount of boron doping can be formed. The boron-doped diamond thin film layer can facilitate the formation of a graphene layer thereon, and is also advantageous for directly performing LED epitaxial growth thereon.

Growth of LED epitaxy on a composite composite diamond substrate can be carried out by conventional LED epitaxy using methods commonly used in the art.

In a preferred embodiment, the method of the present invention may further comprise: growing a patterned graphene layer on the boron doped diamond thin film layer, thereby forming a composite diamond substrate. In order to form a patterned graphene layer, a patterned silicon dioxide mesh layer is first formed on the boron doped diamond thin film layer, followed by depositing copper as a catalyst in the mesh layer, and then forming graphite by chemical vapor deposition. The silicon dioxide layer is removed after the olefin layer, thereby forming a patterned graphene layer. Preferably, growing the patterned graphene layer on the boron doped diamond thin film layer can be performed as follows:

Forming a thin layer of copper within the silica grid;

More specifically, a silica mesh film may be formed on the boron-doped diamond thin film layer at a temperature of 700 to 900 ° C in a vapor phase growth furnace; then, in a vapor phase growth furnace, in a silica mesh Prepare a thin layer of copper mesh, so that the copper layer adheres to the silicon dioxide, and the temperature is lowered to 100-200 ° C in the atmosphere of methane and hydrogen. After vacuuming, argon gas is used as a shielding gas to enter the reaction chamber. High temperature to 1000-1200 ° C, hydrogen and carbon source precursor CH4, to maintain the low pressure state of the reaction chamber, continuous reaction for about 35 minutes, the copper layer as a catalyst will become copper vapor at high temperature, accelerate the decomposition of the carbon source, while conducive to The surface of the buffer layer is deposited, then the carbon source precursor and hydrogen are cut off, the argon flow rate is kept constant, and the temperature is lowered to room temperature, thereby forming a graphene layer on the silica and boron doped diamond thin film layers.

The silicon dioxide layer and the graphene deposited thereon are then removed to obtain a diamond substrate having patterned graphene.

According to a preferred embodiment, as shown in FIG. 9, the patterned graphene layer 51 has a plurality of concave structures arranged on the graphene layer, and an upper plane between the two adjacent concave structures, the concave The top-down structure includes, in order from top to bottom, a transition surface, a side wall and a lower plane, the side wall extending upward along the lower plane edge and forming a recess together with the lower plane, the transition surface extending obliquely upward along the end of the side wall One end of the transition surface is connected to the sidewall, and the other end is connected to the upper plane, and the lower plane is an upper surface of the boron doped diamond thin film layer. The patterned graphene layer may be formed by constructing a silica mesh of a corresponding structure, and the silica mesh may be a silica mesh formed by a granular silica arrangement, such as As shown in FIG. 11, the top surface, the transition surface, the side wall and the lower surface are sequentially arranged from top to bottom, and the side wall extends upward along the lower surface edge, and the transition surface extends obliquely upward along the end of the side wall, the transition One end of the face is connected to the side wall, and the other end is connected to the upper surface, and the lower surface is located on the boron doped diamond film layer. The silica particle structure here corresponds to the concave structure shown in FIG.

Example 1

Referring to Figures 2-11, there is shown a schematic diagram of preparing an LED chip having a composite diamond substrate in accordance with a preferred embodiment of the present invention, and an LED chip having a composite diamond substrate prepared thereby.

Specific steps are as follows:

1. Providing a diamond substrate 1, as shown in FIG. 2, using the <111> plane as the upper surface of the substrate;

2. Processing on the upper surface of the substrate to form a diamond buffer layer 2 comprising a diamond transition layer and a boron doped diamond film layer, as shown in FIG. The growth condition of the diamond transition layer is: in the vapor phase growth furnace, methane and hydrogen are introduced in a volume ratio of 0.35:135, and the temperature of the diamond substrate is adjusted to be in the range of 1100-1180 ° C, the reaction gas pressure is 8.5 kPa, and the growth time is 0.25. A diamond transition layer having a thickness of 0.35 μm was obtained at -0.45 hours. A boron doped diamond film layer is then grown on the transition layer. The growth condition of the boron-doped diamond film layer is as follows: methane, hydrogen, and hydrogen carrying trimethyl borate are introduced into the cavity, and the flow rates are 8 sccm, 200 sccm, and 8 sccm, respectively, that is, the volume ratio of the three is 8:200:8. After the gas pressure reaches 8 kPa and stabilizes, the substrate temperature is adjusted at about 800 ° C, and boron-doped diamond growth is performed, and the growth time is 2 hours;

3. In the vapor phase growth furnace, a silica mesh film 3 is prepared at a temperature of 800 degrees, as shown in Fig. 4 (a silica network formed by the arrangement of granular silica as shown in Fig. 11 can also be formed). Grid, the subsequent steps are the same);

4. In the vapor phase growth furnace, a thin layer of copper mesh is deposited in the silica grid to form a composite copper thin layer of silica mesh 4 (Fig. 5), and the temperature is lowered to 100 degrees in the atmosphere of methane and hydrogen. And then proceed to the next step;

5. In the vapor phase growth furnace, after vacuuming, argon gas is used as a shielding gas to enter the reaction chamber, the temperature is raised to 1000 degrees, hydrogen gas and carbon source precursor CH4 are introduced, and the reaction chamber is kept at a low pressure state for 35 minutes. Then, the carbon source precursor and hydrogen were cut off, the argon flow rate was kept constant, and the temperature was lowered to room temperature to form a graphene layer 5 (Fig. 6).

6. The silica and the graphene layer thereon are removed to obtain a diamond substrate having patterned graphene (Fig. 7 or Fig. 9).

7. Place the above substrate in MOCVD to grow the LED epitaxy 6 (Fig. 8).

Thus, an LED chip having a composite diamond substrate was obtained. The obtained LED chip has excellent thermal conductivity and good crystal quality.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

An LED chip having a composite diamond substrate, comprising: a composite diamond substrate and an LED epitaxial growth on the composite diamond substrate,

Wherein the composite diamond substrate comprises: a diamond substrate, and a diamond buffer layer formed on the diamond substrate, the diamond buffer layer comprising a diamond transition layer on the diamond substrate and growing on the diamond transition layer Boron doped diamond film layer.
The LED chip with a composite diamond substrate of claim 1 wherein said composite diamond substrate further comprises a patterned graphene layer on said boron doped diamond film layer.
The LED chip with a composite diamond substrate according to claim 2, wherein the patterned graphene layer has a plurality of concave structures arranged on the graphene layer, and between the adjacent concave structures In the upper plane, the concave structure includes, in order from top to bottom, a transition surface, a sidewall and a lower plane, the sidewall extending upward along the lower planar edge and forming a recess together with the lower plane, the transition surface along the sidewall The end portion extends obliquely upward, one end of the transition surface is connected to the sidewall, and the other end is connected to the upper plane, and the lower plane is an upper surface of the boron doped diamond thin film layer.
A method for preparing an LED chip having a composite diamond substrate, the method comprising the following steps:

Growing a diamond transition layer on the diamond substrate;

Growing a boron doped diamond thin film layer on the diamond transition layer, thereby forming a composite diamond substrate;

LED epitaxy is grown on the composite diamond substrate.
The method for fabricating an LED chip with a composite diamond substrate according to claim 4, wherein the method further comprises: growing a patterned graphene layer on the boron doped diamond thin film layer, thereby forming a composite diamond Substrate.
A method of fabricating an LED chip having a composite diamond substrate according to claim 4, wherein a diamond transition layer is grown on the <111> face of the diamond substrate.
The method for preparing an LED chip with a composite diamond substrate according to claim 4 or 5, wherein the growth condition of the diamond transition layer on the diamond substrate is: in the vapor phase growth furnace, the volume ratio of the inlet is 0.2-2.3 The methane and hydrogen of 100 are adjusted so that the temperature of the diamond substrate is in the range of 1100-1180 ° C, the reaction gas pressure is 8.5 kPa, and the growth time is 0.25-0.45 hours.
A method of producing an LED chip having a composite diamond substrate according to claim 7, wherein the grown diamond transition layer has a thickness of 0.35 to 0.4 μm.
The method for fabricating an LED chip with a composite diamond substrate according to claim 4 or 5, wherein the growth condition of the boron-doped diamond film layer on the diamond transition layer is: a volume introduced into the vapor phase growth furnace The ratio of 1:20-30:0.8-1.2 methane, hydrogen, hydrogen carrying a boron source, adjusting the gas pressure to 8 kPa-9 kPa, controlling the temperature of the diamond transition layer at 700-900 ° C, and growing for 1-3 hours.
The method of preparing an LED chip having a composite diamond substrate according to claim 9, wherein the boron source is trimethyl borate.
The method for fabricating an LED chip with a composite diamond substrate according to claim 5, wherein the growing the patterned graphene layer on the boron doped diamond thin film layer further comprises the following steps:

Depositing a patterned silicon dioxide mesh film on the boron doped diamond thin film layer;

Forming a thin layer of copper within the silica grid;

Passing hydrogen gas and methane as a carbon source to form a graphene layer on the boron-doped diamond thin film layer and the patterned silicon dioxide mesh film at a high temperature;

The patterned silicon dioxide mesh film and the graphene layer thereon are removed, thereby producing a patterned graphene layer.
The method for fabricating an LED chip with a composite diamond substrate according to claim 11, wherein the patterned graphene layer has a plurality of concave structures arranged on the graphene layer, and two adjacent concave structures Between the upper planes, the concave structure includes, in order from top to bottom, a transition surface, a side wall and a lower plane, the side wall extending upward along the lower plane edge and forming a depression together with the lower plane, the transition surface Extending obliquely upward along the end of the sidewall, one end of the transition surface is connected to the sidewall, and the other end is connected to the upper plane, and the lower plane is the upper surface of the boron doped diamond thin film layer.