TW201409539A - Manufacturing method of epitaxial substrate and product thereof - Google Patents

Abstract

The present invention provides a manufacturing method of epitaxial substrate growing an epitaxial film structure on the substrate to constitute a vertical conduction LED. The epitaxial film structure is mainly composed of gallium nitride material. The manufacturing method comprises steps of: (a) forming a first bonding layer on a first surface of a first single crystal board body; (b) forming a second bonding layer on a first surface of a second single crystal board body; (c) bonding the first bonding layer and the second bonding layer into together to form an adhesive layer; and (d) thinning the second crystal board body on the second surface of the second single board body opposite to the first surface after performing the step (c), wherein the second surface of the second single crystal board body is used for growing the epitaxial film structure. The present invention also provides an epitaxial substrate through the said method.

Description

Method for manufacturing epitaxial substrate and product thereof

The present invention relates to a substrate, and more particularly to a method for fabricating an epitaxial substrate and an article thereof.

The blue/green light emitting diode (LED) is based on the fact that the sapphire epitaxial substrate used for the sapphire is not easy to dissipate heat, and the like, as shown in FIG. Wafer bonding to bond a gallium nitride (GaN) film layer structure 11 on a sapphire epitaxial substrate 10 to a heat-dissipating conductive substrate 100 [see FIG. 1(B)], and Further, a laser lift-off (LLO) process is used to crack the buffer layer 12 between the GaN film layer structure 11 and the sapphire epitaxial substrate 10, so that the sapphire epitaxial substrate 10 is from the GaN film layer structure. 11 is removed [refer to FIG. 1 (C)], thereby solving the aforementioned problem of poor heat dissipation, and forming an upper electrode on the GaN film layer structure 11 after removing the sapphire epitaxial substrate 10 (Fig. Not shown) to produce a vertical feedthrough light emitting diode.

However, it should be additionally noted here that, as shown in FIG. 1(A), before the wafer bonding technique is performed, a surface of the GaN film layer 11 is formed with a metal reflective layer 13 and a metal in advance. Bonding layer 14; then, the metal bonding layer 14 and the other metal bonding layer 15 on the heat-dissipating conductive substrate 100 are bonded to each other by a hot pressing method (ie, wafer bonding technique) [eg, Figure 1 (B)].

Therefore, those skilled in the art should be aware of the implementation of crystal In the case of the round bonding technique, the metal reflective layer 13 will have an oxidation problem due to the high temperature environment in which the hot pressing method is applied, so that the reflectance of the metal reflective layer 13 is seriously adversely affected. Furthermore, in the LLO process implemented after the wafer bonding technique, the GaN film layer structure 11 is also damaged by the high-energy laser beam of the LLO process, thereby affecting the characteristics of its leakage current. For a description of the method for fabricating a vertical-conducting light-emitting diode and its structure, reference is made to the description of the earlier published patent publications such as TW200812105 and TW201123524.

A cost problem that needs to be broken here is that even the heat dissipation problem can be initially obtained through the above-described manufacturing method/structure; however, the GaN film layer structure 11 must always be grown on the expensive sapphire epitaxial substrate 10, The overall fabrication cost of the vertical-conducting light-emitting diode cannot be pulled down.

It can be seen from the above description that the method for manufacturing the epitaxial substrate and the structure of the product thereof can reduce the cost of the raw material of the vertical-conducting light-emitting diode, so that the method for manufacturing the vertical-conducting light-emitting diode can be obtained according to the structural improvement of the epitaxial substrate. Improvements and thus solving problems such as leakage current or even high temperature oxidation of the metal reflective layer are problems that need to be improved by those skilled in the art.

Accordingly, it is an object of the present invention to provide a method of fabricating an epitaxial substrate.

Another object of the present invention is to provide an epitaxial substrate.

Therefore, the method for fabricating the epitaxial substrate of the present invention is to grow an epitaxial film layer structure thereon to form a vertical conductive light emitting diode. The crystal film layer structure is composed of a GaN-based material. The manufacturing method comprises the steps of: (a) forming a first bonding layer on a first surface of a first single crystal plate body; and (b) forming a first surface on a first surface of a second single crystal plate body. a second bonding layer; (c) bonding the first bonding layer and the second bonding layer by heat pressing, and thereby forming a bonding layer; and (d) after the step (c), The second single crystal plate body is thinned from a second surface of the second single crystal plate body opposite to the first surface thereof, and the second surface of the second single crystal plate body is used to grow the epitaxial film layer structure.

In addition, the epitaxial substrate of the present invention is used to grow an epitaxial film layer structure thereon to form a vertical-conducting light-emitting diode structure, which is composed of a gallium nitride-based material. Composition. The epitaxial substrate of the present invention comprises: a first single crystal plate body, a second single crystal plate body, and a bonding layer. The second single crystal plate body has a first surface and a second surface disposed oppositely, and the second surface of the second single crystal plate body is configured to grow the epitaxial film layer, and the second single crystal plate The thickness of the body is less than 10 μm. The adhesive layer is bonded between the first single crystal plate body and the first surface of the second single crystal plate body.

The invention has the advantages that the improved epitaxial substrate structure can reduce the raw material cost of the vertical-conducting light-emitting diode, and the method for manufacturing the vertical-conducting light-emitting diode can be improved according to the structural improvement of the epitaxial substrate. In order to solve the problem of leakage current or even high temperature oxidation of the metal reflective layer.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to FIG. 2, a preferred embodiment of the method for fabricating the epitaxial substrate 2 of the present invention is used to grow an epitaxial film layer structure 3 thereon to form a vertical-conducting light-emitting diode (see FIG. 6). The epitaxial film layer structure 3 is composed of a GaN-based material. The manufacturing method of the preferred embodiment of the present invention comprises the steps of: (a) forming a first bonding layer 231 on a first surface 211 of a first single crystal panel body 21; (b) forming a second single crystal A first surface shape 221 of the board body 22 is formed into a second bonding layer 232; (c) the first bonding layer 231 and the second bonding layer 232 are bonded together by heat pressing, and thereby forming a After the step (c), the second single crystal plate body 22 is thinned from a second surface 222 of the second single crystal plate body 22 opposite to the first surface 221 thereof, The second surface 222 of the second single crystal plate body 22 is used to grow the epitaxial film layer structure 3.

Preferably, the thickness of the second single crystal plate body 22 of the step (d) after thinning is less than 10 μm. In the preferred embodiment of the invention, step (d) is to thin the second single crystal plate body 22 using chemical mechanical polishing (CMP).

A preliminary description of the above manufacturing method of the preferred embodiment of the present invention may be It is understood that the epitaxial substrate 2 obtained by the manufacturing method of the preferred embodiment of the present invention is shown in step (d) of FIG. 2, which is used to grow the epitaxial film layer structure 3 thereon to constitute the vertical A general-purpose light-emitting diode (see FIG. 6), the epitaxial film layer structure 3 is composed of a material mainly composed of gallium nitride. The epitaxial substrate 2 includes the first single crystal plate body 21, the second single crystal plate body 22, and the adhesive layer 23. The second single crystal plate body 22 has a first surface 221 and a second surface 222 disposed oppositely, and the second surface 222 of the second single crystal plate body 22 is used to grow the epitaxial film layer 3, and the first The thickness of the two single crystal plate bodies 22 is less than 10 μm. The adhesive layer 23 is bonded between the first single crystal plate body 21 and the first surface 221 of the second single crystal plate body 22.

Preferably, after the step (a) and the step (b) and before the step (c), the first bonding layer 231 formed by the step (a) and the step (b) is further included. The second bonding layer 232 is subjected to an RCA cleaning process (not shown) to remove the organic materials and metal particles on the surface of the first bonding layer 231 and the second bonding layer 232 and form a dipole on the surface thereof (dipole) And the average surface roughness of the first bonding layer 231 and the second bonding layer 232 is less than 0.4 nm, so that in the state in which the step (c) is performed, the first bonding layer 231 is When the second bonding layer 232 is in face-to-face contact, it can be initially adsorbed by van der Waals' forces on both surfaces thereof.

Preferably, the first single crystal plate body 21 is composed of a first single crystal material suitable for being removed by a wet etchant; the second single crystal plate body 22 is made of a second single crystal material. The second single crystal material is ruthenium (111), and the first single crystal material and the second single crystal material of the preferred embodiment of the present invention exhibit selective etching on the wet etchant. The characteristics are such that the wet etchant etch rate of the first single crystal material is much greater than the etch rate of the second single crystal material. In the preferred embodiment of the present invention, the first single crystal material is tantalum (100); the first bonding layer 231 and the second bonding layer 232 are made of yttrium oxide (SiO ₂ ); The adhesive layer 23 is composed of ruthenium oxide; further, the wet etchant suitable for use in the preferred embodiment of the present invention is potassium hydroxide (KOH).

Preferably, the thickness of the first bonding layer 231 is between 0.4 μm and 2 μm; the thickness of the second bonding layer 232 is between 0.4 μm and 2 μm (ie, the bonding layer 23 The thickness of the step (c) is between 500 ° C and 1100 ° C, and the implementation pressure of the step (c) is between 5 MPa and 15 MPa. between.

It should be noted that the related description and application of the epitaxial substrate 2 of the preferred embodiment of the present invention to further form a vertical-conducting light-emitting diode are briefly described below.

First, referring to FIG. 3, a person skilled in the art can form a mask having a high density and having an opening 50 on a second surface 212 of the first single crystal board body 21 away from the adhesive layer 23. Layer 5, and according to the selective etching difference of KOH between the first single crystal plate body [i.e., ruthenium (100)] 21 and the second single crystal plate body [i.e., ruthenium (111)] 21, KOH is used. To quickly remove the first single crystal plate body 21 exposed outside the opening 50, thereby forming a space through the first and second surfaces 211, 212 and defining a space 210 in the first single crystal board body 21. surrounding surface 213; wherein, KOH wet etching action is to terminate on the adhesive layer (SiO ₂₎ 23.

Further, referring to Figure 4, dry etching using ion coupled plasma (ICP) The bonding layer 23, the second single crystal plate body 22 and the partial epitaxial film layer structure 3 exposed outside the space 210 are sequentially removed from the bonding layer 23 toward the epitaxial film layer structure 3, thereby The bonding layer 23, the second single crystal board body 22 and the epitaxial film layer structure 3 are respectively formed with an inner annular surface 233, 223, 36, and the inner surrounding surface 213 of the first single crystal board body 21 and the like The inner annular faces 233, 223, 36 collectively define a cavity 20 and expose an n-type GaN layer 31 in the epitaxial film layer structure 3 outside the cavity 20. Thereafter, the mask layer 5 is removed (as shown in FIG. 5). As can be seen from the description of this paragraph, in order to avoid the ICP dry etching method is too long; therefore, as described in the preceding paragraphs, the thickness of the second single crystal board body 22 and the bonding layer 23 of the preferred embodiment of the present invention is better. It is controlled between 10 μm and 0.8 μm to 4 μm, respectively.

As shown in FIG. 6 , a person skilled in the art can form a plurality of first electrodes 4 spaced apart from each other on the surface of the epitaxial film layer structure 3 before the processes of FIG. 3 to FIG. 5 , or even A transparent conductive layer (not shown) is formed between the epitaxial film layer structure 3 and the first electrodes 4 to serve as a current spreading layer. Finally, a metal reflective layer 6, a second electrode layer 7, and a heat dissipation layer 8 are sequentially formed from a side on which the cavity 20 is formed; the metal reflective layer 6 covers the n-type GaN layer 31, the inner rings a surface 36, 223, 233, an inner surrounding surface 213 of the first single crystal panel body 21 and a second surface 212 thereof, the second electrode layer 7 covers the metal reflective layer 6, and the heat dissipation layer 8 covers the second electrode Layer 7, and thereby completing the bottom ohmic contact of the vertical-conducting light-emitting diode.

Referring to FIG. 3, FIG. 4 and FIG. 6, the epitaxial substrate 2 obtained by the preferred embodiment of the present invention utilizes the second single crystal plate body on the one hand [ie, Si(111)]22, to reduce the lattice mismatch caused by the epitaxial film layer structure 3 during epitaxial growth, thereby replacing the more expensive sapphire epitaxial substrate and reducing the fabrication Raw material cost when vertically conducting a light-emitting diode.

In another aspect, the preferred embodiment of the present invention also utilizes the first single crystal plate body 21 [ie, Si (100)] and the second single crystal plate body 22 [ie, Si (111)]. Selective etching characteristics of the wet etchant (ie, KOH) to rapidly form the space 210 in the first single crystal plate body 21; and further removing the bare by the ICP dry etching method a bonding layer 23 outside the space 210, a second single crystal plate body [ie, Si(111)] 22 and a portion of the epitaxial film layer structure 3, such that the n-type GaN layer 31 is exposed outside the cavity 20, so that The metal reflective layer 6, the second electrode layer 7 and the heat dissipation layer 8 can be implemented in the last step of the method of manufacturing the vertical conductive light-emitting diode, and the fabrication process of the bottom ohmic contact is completed, thereby avoiding the The metal reflective layer 6 has an oxidation problem derived from a hot pressing method of a high temperature process, and enhances the reflectance of the metal reflective layer 6.

Furthermore, since the cavity 20 is formed by the inner annular surface 36 of the epitaxial film layer structure 3 and the inner surrounding surface 213 and the inner annular surfaces 233, 223 of the epitaxial substrate 2 of the preferred embodiment of the present invention. It is defined; therefore, the coating area of the metal reflective layer 6 is relatively improved, and the overall heat dissipation area of the subsequently completed vertical-conducting light-emitting diode is also increased.

Moreover, the structural design of the epitaxial substrate 2 of the preferred embodiment of the present invention can omit the laser lift-off (LLO) process used in the prior art when the vertical-conducting light-emitting diode is subsequently fabricated. Crystal film layer structure 3 is free of Damage to the laser beam subjected to high energy can reduce the leakage current problem described in the prior art.

In summary, the method for fabricating the epitaxial substrate of the present invention and the article thereof, the improved epitaxial substrate structure can reduce the raw material cost of the vertical-conducting light-emitting diode, and the method for manufacturing the vertical-conducting light-emitting diode It is possible to obtain an improvement according to the structural improvement of the epitaxial substrate, thereby solving the problems of leakage current or even high-temperature oxidation of the metal reflective layer, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

2‧‧‧ epitaxial substrate

20‧‧‧ cavity

21‧‧‧The first single crystal plate body

210‧‧‧ Space

211‧‧‧ first surface

212‧‧‧ second surface

Surrounded by 213‧‧

22‧‧‧Second single crystal plate body

221‧‧‧ first surface

222‧‧‧ second surface

223‧‧‧ Inner torus

23‧‧‧Bonded layer

231‧‧‧First bonding layer

232‧‧‧Second bonding layer

233‧‧‧ Inner torus

3‧‧‧ epitaxial film structure

31‧‧‧n-type GaN layer

36‧‧‧ Inner torus

4‧‧‧First electrode

5‧‧‧mask layer

50‧‧‧ openings

6‧‧‧Metal reflector

7‧‧‧Second electrode layer

8‧‧‧heat layer

1 is a schematic diagram of a component fabrication process, illustrating a basic manufacturing process of a conventional vertical-conducting light-emitting diode; FIG. 2 is a schematic diagram of a component fabrication process, illustrating a preferred embodiment of a method for fabricating an epitaxial substrate of the present invention; A front view showing an epitaxial substrate obtained by the preferred embodiment of the present invention, which is applied to a step of a process for fabricating a vertical-conducting light-emitting diode; FIG. 4 is a front view showing the continuity a step after 3; FIG. 5 is a front view showing a step continuing after FIG. 4; and FIG. 6 is a front view showing a step continuing after FIG. A finished vertical light emitting diode is completed.

2‧‧‧ epitaxial substrate

21‧‧‧The first single crystal plate body

211‧‧‧ first surface

22‧‧‧Second single crystal plate body

221‧‧‧ first surface

222‧‧‧ second surface

23‧‧‧Bonded layer

231‧‧‧First bonding layer

232‧‧‧Second bonding layer

3‧‧‧ epitaxial film structure

Claims (12)

An epitaxial substrate is formed by growing an epitaxial film layer structure to form a vertical-conducting light-emitting diode structure, and the epitaxial film layer structure is made of a material mainly composed of gallium nitride. The method includes the steps of: (a) forming a first bonding layer on a first surface of a first single crystal plate body; and (b) forming a first surface of a second single crystal plate body. a second bonding layer; (c) bonding the first bonding layer and the second bonding layer by heat pressing, and thereby forming a bonding layer; and (d) in the step (c) Thereafter, the second single crystal plate body is thinned from a second surface of the second single crystal plate body opposite to the first surface thereof, and the second surface of the second single crystal plate body is used to grow the epitaxial crystal Membrane structure. The method for fabricating an epitaxial substrate according to claim 1, wherein the first single crystal plate body is composed of a first single crystal material suitable for being removed by a wet etchant; The second single crystal plate body is composed of a second single crystal material, the second single crystal material is germanium (111), and the etching rate of the wet single etchant to the first single crystal material is much larger than the first The etching rate of the two single crystal materials. The method for fabricating an epitaxial substrate according to claim 2, wherein the first single crystal material is ruthenium (100). The method for fabricating an epitaxial substrate according to claim 3, wherein the first bonding layer and the second bonding layer are made of yttrium oxide to make. The method for fabricating an epitaxial substrate according to the fourth aspect of the invention, wherein the implementation temperature of the step (c) is between 500 ° C and 1100 ° C, and the implementation pressure of the step (c) is between 5 Between MPa and 15 MPa. The method for fabricating an epitaxial substrate according to claim 1, wherein the thickness of the first bonding layer is between 0.4 μm and 2 μm; and the thickness of the second bonding layer is 0.4 Between μm and 2 μm. According to the method for fabricating an epitaxial substrate according to the first aspect of the patent application, after the step (a) and the step (b) and before the step (c), the step (a) and the step are further included. (b) forming the first bonding layer and the second bonding layer to apply an RCA cleaning process to remove the first bonding layer and the organic material and metal particles on the surface of the second bonding layer and form on the surface thereof a dipole, and an average surface roughness of the first bonding layer and the second bonding layer is less than 0.4 nm, so that the first bonding layer and the first layer are performed in a state in which the step (c) is performed When the two bonding layers are in face-to-face contact, they can be initially adsorbed by the van der Waals force of both surfaces. The method for fabricating an epitaxial substrate according to the first aspect of the invention, wherein the thickness of the second single crystal plate body of the step (d) after being thinned is less than 10 μm. An epitaxial substrate is configured to grow an epitaxial film layer structure thereon to form a vertical conductive light emitting diode layer, wherein the epitaxial film layer structure is composed of a material mainly composed of gallium nitride, The epitaxial substrate comprises: a first single crystal plate body; a second single crystal plate body having a first surface and a second surface disposed oppositely, the second surface of the second single crystal plate body is configured to grow the epitaxial film layer, and the second single crystal The thickness of the board body is less than 10 μm; and a bonding layer is bonded between the first single crystal board body and the first surface of the second single crystal board body. The epitaxial substrate according to claim 9, wherein the first single crystal plate body is composed of a first single crystal material suitable for being removed by a wet etchant; the second single crystal The plate body is composed of a second single crystal material, the second single crystal material is ruthenium (111), and the wet etchant etch rate of the first single crystal material is much larger than the second single crystal The etch rate of the material. The epitaxial substrate according to claim 10, wherein the first single crystal material is ruthenium (100). The epitaxial substrate according to claim 11, wherein the adhesive layer is composed of yttrium oxide, and the thickness of the adhesive layer is between 0.8 μm and 4 μm.