KR100631416B1 - Method for forming vertically structured gan type light emitting diode device - Google Patents

Abstract

A method for manufacturing a vertically structured GaN LED is provided to prevent crack of a semiconductor layer by using an adhesive layer made of photoresist instead of a conventional metal and by using a wet-etching process instead of a dicing or scriber process. A light emitting structure(120) including an n-type GaN semiconductor layer(121), an active layer(122) and a p-type GaN semiconductor layer(123) is formed on a transparent substrate. A plurality of p-type electrodes(150) spaced apart from each other are formed on the light emitting structure. A unit LED is formed by dicing the light emitting structure. A plated seed layer is formed on the p-type electrode. A silicon substrate(190) having a hole to expose the plated seed layer is formed on the resultant structure. An electroplating layer(210) is then formed without covering the surface of the silicon substrate. The n-type GaN semiconductor layer is exposed by removing the transparent substrate. N-type electrodes(180) are formed on the exposed n-type GaN semiconductor layer, respectively. The silicon substrate is then removed by a wet-etching process.

Description

Method for manufacturing vertically structured gallium nitride-based light emitting diode device {Method for forming vertically structured GaN type Light Emitting Diode device}

1A to 1F are cross-sectional views sequentially illustrating a method of manufacturing a vertical gallium nitride based LED device according to the prior art.

2A through 2H are cross-sectional views sequentially illustrating a method of manufacturing a vertical gallium nitride based LED device according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

110: sapphire substrate 120: light emitting structure

121 n-type nitride semiconductor layer 122 active layer

123: p-type nitride semiconductor layer 150: p-type electrode

160: adhesive layer 180: n-type electrode

190 silicon substrate 200 seed layer

210: electroplating layer

The present invention relates to a method for manufacturing a vertical structure (vertical electrode type) gallium nitride-based (GaN) light emitting diode (hereinafter referred to as "LED") device, and more specifically, a structure support layer forming process and a unit LED The present invention relates to a method of manufacturing a vertical gallium nitride-based LED device that can prevent the damage of the light emitting structure consisting of gallium nitride-based layer and the active layer in the light emitting structure separation process by the size of the device.

In general, gallium nitride-based LED devices grow on sapphire substrates, but these sapphire substrates are hard, electrically nonconducting, and have poor thermal conductivity, which reduces the size of gallium nitride-based LED devices, thereby reducing manufacturing costs, or reducing light output and chip characteristics There was a limit to the improvement. In particular, in order to increase the output power of the LED device is required to apply a large current, it is very important to solve the heat emission problem of the LED device.

As a means to solve this problem, a vertical gallium nitride-based LED device in which a sapphire substrate is removed by a laser lift-off (LLO) technique has been proposed.

Next, a method of manufacturing a conventional vertical gallium nitride based LED device will be described in detail with reference to FIGS. 1A to 1F.

1A to 1F are cross-sectional views sequentially illustrating a method of manufacturing a vertical gallium nitride based LED device according to the prior art.

First, as shown in FIG. 1A, a light emitting structure 120 made of a gallium nitride based semiconductor layer is formed on a sapphire substrate 110. In this case, the light emitting structure 120 has a structure in which the n-type gallium nitride-based semiconductor layer 121, the multi-well GaN / InGaN active layer 122 and the p-type gallium nitride-based semiconductor layer 123 are sequentially stacked Have

Subsequently, as illustrated in FIG. 1B, a plurality of p-type electrodes 150 are formed on the p-type gallium nitride based semiconductor layer 123. In this case, the p-type electrode 150 serves as an electrode and a reflective film.

Next, as illustrated in FIG. 1C, the light emitting structure 120 is separated into unit LED elements by a reactive ion etching (RIE) process.

Subsequently, as shown in FIG. 1D, an adhesive layer 160 is formed on the p-type electrode 150 to attach the structural support layer by eutectic bonding. Then, the adhesive layer 160 has a predetermined temperature. A pressure bonding process is performed to bond the structural support layer 170 onto the adhesive layer 160. In this case, the structural support layer 170 serves as a support layer and an electrode of the final LED device.

However, in the bonding process of bonding the structural support layer according to the prior art as described above, since the bonding layer 160 is bonded at a high pressure at a temperature of 200 ℃ to 300 ℃ using a metal such as Au as the adhesive layer 160, the bonded result is room temperature As a result, when cooling, there is a problem of causing a defect such as a crack on the surface of the gallium nitride-based semiconductor layer constituting the light emitting structure due to the difference in thermal expansion coefficient of the light emitting structure.

Thereafter, as shown in FIG. 1E, the sapphire substrate 110 is removed through an LLO process.

Subsequently, as shown in FIG. 1F, after forming n-type electrodes 180 on the n-type gallium nitride based semiconductor layer 121 separated from the sapphire substrate (not shown), respectively, The structural support layer 170 is separated into unit LED elements by dicing or scribing processes to form a plurality of gallium nitride based LED elements.

However, when the structural support layer 170 is separated by a dicing or scribing process, the structural support layer 170 and the light emitting structure 120 disposed thereunder are broken or chipped. There is a problem that the unit LED elements separated by the chipping phenomenon are shorted to each other.

As described above, when manufacturing the vertical gallium nitride-based LED device according to the prior art, there is a problem that the characteristics and reliability of the vertical gallium nitride-based LED device is lowered due to the above problems.

Accordingly, an object of the present invention, in order to solve the above problems, in the process of forming the structure support layer and the light emitting structure separation process to the size of the unit LED device, without damaging the light emitting structure consisting of gallium nitride layer and the active layer It is to provide a method of manufacturing a vertical gallium nitride-based LED device capable of separating the light emitting structure in size.

In order to achieve the above object, the present invention is to form a light emitting structure having a structure in which an n-type gallium nitride-based semiconductor layer, an active layer and a p-type gallium nitride-based semiconductor layer are sequentially stacked on a transparent substrate, the light emitting structure Forming a plurality of p-type electrodes spaced apart at predetermined intervals on the substrate, etching the light emitting structure to separate unit LEDs having one p-type electrode, and depositing a plating seed layer on the p-type electrode Forming a silicon substrate, the silicon substrate having a hole exposing a portion of the upper surface of the plating seed layer on a resultant on which the plating seed layer is formed; and using the plating seed layer, an upper surface of the silicon substrate. Forming an electroplating layer to a height, exposing the n-type gallium nitride based semiconductor layer by removing the transparent substrate, and exposing the exposed n-type quality Forming an n-type electrode, respectively on the gallium-based semiconductor layer, and provides a method for producing the vertical structure GaN-based LED element, comprising the step of removing by wet etching the silicon substrate.

In addition, in the method of manufacturing a vertical gallium nitride-based LED device of the present invention, before the step of forming a silicon substrate having a hole for exposing a portion of the upper surface of the plating seed layer on the resultant plating layer is formed. It is preferable to further include forming an adhesive layer on the plating seed layer.

In addition, in the method of manufacturing a vertical gallium nitride-based LED device of the present invention, the step of forming a silicon substrate having a hole for exposing a portion of the upper surface of the plating seed layer on the resultant the plating seed layer is formed, Forming an adhesive layer on a resultant on which the plating seed layer is formed, bonding a silicon substrate on the adhesive layer, and forming a photoresist pattern defining an upper portion of the plating seed layer on the silicon substrate; And etching the silicon substrate using the photoresist pattern as an etch mask to form a hole exposing a portion of the upper surface of the plating seed layer.

In addition, in the manufacturing method of the vertically structured gallium nitride-based LED device of the present invention, the adhesive layer is formed by using a photosensitive material or a double-sided dry film, it is preferably removed together during the wet etching process for removing the silicon substrate. Do.

In addition, in the method of manufacturing a vertical gallium nitride-based LED device of the present invention, the plating seed layer is formed of a two-layer structure in which an adhesive layer and a conductive layer are sequentially stacked, the adhesive layer is formed using chromium or titanium The conductive layer is preferably formed using any one selected from the group consisting of copper, gold and nickel.

In addition, in the method of manufacturing a vertical gallium nitride-based LED device of the present invention, the step of wet etching to remove the silicon substrate, it is preferable to use a KOH solution or TMAH solution as an etchant.

In addition, in the manufacturing method of the vertical structure gallium nitride-based LED device of the present invention, after the step of forming the light emitting structure by etching the light emitting structure to separate the unit LED size, and the separated p-type gallium nitride system And forming p-type electrodes on the semiconductor layer, respectively. That is, the light emitting structure is separated into unit LED sizes, and then p-type electrodes are formed, or a plurality of p-type electrodes are formed on the light-emitting structure by changing the order of processing, and then the light-emitting structure is formed to have one p-type electrode. It can also be separated by LED size.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like parts throughout the specification.

Now, a method of manufacturing a vertical gallium nitride based LED device according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 2A to 2H.

2A through 2H are cross-sectional views sequentially illustrating a method of manufacturing a vertical gallium nitride based LED device according to an exemplary embodiment of the present invention.

First, as shown in FIG. 2A, a light emitting structure 120 made of a gallium nitride based semiconductor layer is formed on the transparent substrate 110. In this case, the light emitting structure 120 has a structure in which the n-type gallium nitride-based semiconductor layer 121, the multi-well GaN / InGaN active layer 122 and the p-type gallium nitride-based semiconductor layer 123 are sequentially stacked Have

Here, the transparent substrate 110 is preferably formed using a transparent material including sapphire, in addition to sapphire, the substrate 110 is zinc oxide (ZnO), gallium nitride (GaN) , Silicon carbide (SiC) and aluminum nitride (AlN).

In addition, the p-type and n-type gallium nitride-based semiconductor layer 121, 123 and the active layer 122 is Al x In y Ga (1-xy) N composition formula (where 0≤x≤1, 0≤y≤1, 0≤x gallium nitride-based semiconductor material having + y ≦ 1) and may be formed through known nitride deposition processes such as MOCVD and MBE processes.

Meanwhile, the active layer 130 may be formed of one quantum well layer or a double hetero structure. In addition, the active layer 130 determines whether the diode is a green light emitting device or a blue light emitting device by the amount of indium (In) constituting it. More specifically, about 22% of indium is used for light emitting devices having blue light, and about 40% of indium is used for light emitting devices having green light. That is, the amount of indium used to form the active layer 130 varies depending on the required blue or green wavelength.

Therefore, the active layer 122 has a great influence on the characteristics and reliability of the gallium nitride-based LED device as described above, and thus, cracks or conductive materials penetrate the overall gallium nitride-based LED device manufacturing process. It should be safe from the same defect.

Subsequently, as illustrated in FIG. 2B, a plurality of p-type electrodes 150 are formed on the p-type gallium nitride based semiconductor layer 123. In this case, the p-type electrode 150 is preferably formed to simultaneously serve as an electrode and a reflective film. Accordingly, in the present embodiment, the p-type electrode 150 has a structure in which Ni / Ag is sequentially stacked.

Then, as shown in Figure 2c, the light emitting structure 120 is separated into the size of the unit LED device by a reactive ion etching (RIE) process.

On the other hand, in the present embodiment, after forming a plurality of p-type electrode 150 on the light emitting structure 120, it was separated into a unit LED size having one p-type electrode, but this is not limited thereto. In another embodiment, the light emitting structure 120 may be separated into unit LED sizes by changing the process order, and then p-type electrodes may be formed on the separated light emitting structures.

Subsequently, as illustrated in FIG. 2D, a plating seed layer 200 which serves as a crystal nucleus is formed on the p-type electrode 150 to be described later. In this case, the plating seed layer 200 is preferably formed in a two-layer structure in which the adhesive layer and the conductive layer are sequentially stacked to improve the adhesion between the conductive layer and the p-type electrode 150. In this embodiment, the adhesive layer is formed using chromium or titanium, and the conductive layer is formed using any one metal selected from the group consisting of copper (Cu), gold (Au), and nickel (Ni). .

Next, a silicon substrate 190 having a hole 195 exposing a portion of the upper surface of the plating seed layer 200 is formed on the plating seed layer 200. Here, the plating seed layer 200 and the silicon substrate 190 are bonded using the adhesive layer 160. In particular, the adhesive layer 160 according to the present invention is preferably formed using a photosensitive material or a double-sided dry film that can be bonded at room temperature at atmospheric pressure.

Accordingly, the present invention is a problem according to the eutectic bonding method using a conventional metal adhesive layer, that is, using a metal adhesive layer such as gold (Au) using a high pressure at a temperature of 200 ℃ ~ 300 ℃, and then bonded the resultant When cooling to room temperature, it is possible to prevent defects such as cracks occurring on the surface of the gallium nitride-based semiconductor layer constituting the light emitting structure due to the difference in thermal expansion coefficient of the light emitting structure, thereby improving the characteristics and reliability of the device.

2E, the electroplating layer 210 is formed by electroplating using the plating seed layer 200 exposed through the hole 195 of the silicon substrate 190 as a crystal nucleus. In this case, the electroplating layer 210 is preferably formed so as not to cover the entire upper surface of the silicon substrate 190 to facilitate the subsequent process of removing the silicon substrate 190.

Here, the electroplating layer 210 serves as a supporting layer and an electrode of the final LED device. In addition, since the electroplating layer 210 is made of a metal having excellent thermal conductivity, for example, copper, gold, nickel, and the like, heat generated from the LED device can be easily released to the outside. Therefore, even when a high current is applied to the LED element, heat can be efficiently discharged, thereby preventing the phenomenon of deterioration of the characteristics of the LED element even at a high current.

Then, as illustrated in FIG. 2F, the transparent substrate 110 is removed through an LLO process.

Subsequently, as shown in FIG. 2G, the n-type electrode 180 is formed on the n-type gallium nitride based semiconductor layer 121 where the transparent substrate 110 is removed and exposed.

Next, as shown in FIG. 2H, the silicon substrate 190 and the adhesive layer 160 are removed to form a gallium nitride-based LED device having a unit LED device size.

As described above, the present invention proceeds with the wet etching process of removing the silicon substrate rather than the conventional dicing or scriber process in order to separate the structural support layer supporting the gallium nitride-based LED device of the unit LED device size. In this case, it is possible to prevent a problem that the light emitting structure is broken or damaged.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

As described above, the present invention uses a photosensitive material or a double-sided dry film that can be bonded at atmospheric pressure at room temperature when bonding a structural support layer on a p-type electrode, to a eutectic bonding method using a conventional metal adhesive layer. According to the problem, that is, a metal adhesive layer such as gold (Au) is bonded at a high pressure at a temperature of 200 ℃ ~ 300 ℃, and when the bonded result is cooled to room temperature, forming a light emitting structure by the thermal expansion coefficient difference of the light emitting structure The problem that a defect such as a crack occurring in the surface of the gallium nitride based semiconductor layer occurs can be prevented.

In addition, the present invention, by using an electroplating layer made of a metal having a high thermal conductivity as the structure support layer, it is possible to easily discharge the heat generated in the LED element when the large current is applied to the outside.

In addition, the present invention is a separation process because a wet etching process for removing the silicon substrate rather than the conventional dicing or scriber process to separate the structural support layer for supporting the gallium nitride-based LED device of the unit LED element size, In this case, it is possible to prevent a problem that the light emitting structure is broken or damaged.

Accordingly, the present invention can improve the characteristics and reliability of the vertical gallium nitride-based LED device.

Claims (9)

Forming a light emitting structure having a structure in which an n-type gallium nitride-based semiconductor layer, an active layer, and a p-type gallium nitride-based semiconductor layer are sequentially stacked on the transparent substrate; Forming a plurality of p-type electrodes spaced apart at predetermined intervals on the light emitting structure; Etching the light emitting structure to separate a unit LED having one p-type electrode; Forming a plating seed layer on the p-type electrode; Forming a silicon substrate having a hole exposing a portion of an upper surface of the plating seed layer on a resultant on which the plating seed layer is formed; Forming an electroplating layer using the plating seed layer so as not to cover the entire upper surface of the silicon substrate; Removing the transparent substrate to expose the n-type gallium nitride based semiconductor layer; Forming n-type electrodes on the exposed n-type gallium nitride based semiconductor layers, respectively; And Removing the silicon substrate by wet etching; and manufacturing a vertical gallium nitride based LED device. The method of claim 1, And forming an adhesive layer on the plating seed layer prior to forming a silicon substrate having a hole exposing a portion of the upper surface of the plating seed layer on the resultant on which the plating seed layer is formed. Vertical structure gallium nitride-based LED manufacturing method. The method of claim 1, Forming a silicon substrate having a hole on the resultant formed with the plating seed layer to expose a portion of the upper surface of the plating seed layer, Forming an adhesive layer on a resultant on which the plating seed layer is formed; Bonding a silicon substrate on the adhesive layer; Forming a photoresist pattern on the silicon substrate to define an upper portion of the plating seed layer; And And etching the silicon substrate using the photoresist pattern as an etch mask to form a hole for exposing a portion of the upper surface of the plating seed layer. The method according to claim 2 or 3, The adhesive layer is a method of manufacturing a vertical gallium nitride-based LED device, characterized in that formed using a photosensitive material or a double-sided dry film. The method of claim 1, The plating seed layer is a method of manufacturing a vertical gallium nitride-based LED device, characterized in that formed in a two-layer structure in which the adhesive layer and the conductive layer are sequentially stacked. The method of claim 5, The adhesive layer is a method of manufacturing a vertical gallium nitride-based LED device, characterized in that formed using chromium or titanium. The method of claim 5, The conductive layer is a method of manufacturing a vertical gallium nitride-based LED device, characterized in that formed using any one metal selected from the group consisting of copper, gold and nickel. The method of claim 1, The wet etching of the silicon substrate may be performed by using a KOH solution or a TMAH solution as an etchant. The method of claim 1, After forming the light emitting structure, etching and separating the light emitting structure into unit LED sizes, and forming p-type electrodes on the separated p-type gallium nitride based semiconductor layer, respectively. The manufacturing method of the vertical structure gallium nitride system LED element which consists of.

Images