KR101209487B1 - Semiconductor Light Emitting Device and Method for Manufacturing Thereof - Google Patents

Abstract

The semiconductor light emitting device according to an aspect of the present invention for manufacturing a semiconductor light emitting device having excellent characteristics by preventing the occurrence of warpage or cracking of the substrate due to the difference in thermal expansion coefficient when growing the GaN-based semiconductor layer on the sapphire substrate The manufacturing method of the sapphire substrate; A thin film formed on a lower surface of the sapphire substrate; A first GaN-based semiconductor layer formed on an upper surface of the sapphire substrate; An active layer formed on the first GaN-based semiconductor layer; A second GaN-based semiconductor layer formed on the active layer; A first electrode formed on the first GaN-based semiconductor layer on which the active layer and the second GaN-based semiconductor layer are not formed; And a second electrode formed on the second GaN-based semiconductor layer.

Description

Semiconductor Light Emitting Device and Method for Manufacturing Thereof}

The present invention relates to a semiconductor device, and more particularly to a nitride semiconductor light emitting device.

The nitride semiconductor light emitting device has a light emitting area covering ultraviolet, blue, and green areas. In particular, GaN-based semiconductor light emitting device is a high-speed switching or high-output device, such as an optical element of a blue / green light emitting diode (LED), a metal semiconductor field effect transistor (MESFET) or a high electron mobility transistor (HEMT) in the application field It is applied to electronic devices.

Since GaN-based semiconductor light emitting devices do not have a substrate to be lattice matched and have a large difference in lattice constant and thermal expansion coefficient, it is difficult to grow a high quality nitride semiconductor thin film. Therefore, sapphire (Al2O3) is generally used to grow a GaN semiconductor thin film. The substrate is mainly used. In addition, a silicon carbide (SiC) substrate or a GaN single crystal substrate is used.

However, when GaN is grown on a sapphire substrate, a stress is concentrated at the interface between sapphire and GaN due to a difference in thermal expansion coefficients of sapphire and GaN, thereby deforming the sapphire substrate.

In addition, the sapphire substrate is mainly used 2 inches substrate, but 3 inches, 4 inches, 6 inches, or 8 inches substrates are in mass production or development to improve the yield, and as the diameter of the sapphire substrate increases, the thermal expansion Deformation of the sapphire substrate caused by the thermal stress due to the coefficient difference is more serious, there is a problem that the quality of the semiconductor light emitting device can be significantly reduced.

The present invention is to solve the above-described problems, a semiconductor light emitting device having excellent characteristics by preventing the deformation of the substrate due to the difference in thermal expansion coefficient between sapphire and GaN when growing the GaN-based semiconductor layer on the sapphire substrate and It is the technical problem to provide the manufacturing method.

A semiconductor light emitting device according to an aspect of the present invention for achieving the above object, a sapphire substrate; A thin film formed on a lower surface of the sapphire substrate; A first GaN-based semiconductor layer formed on an upper surface of the sapphire substrate; An active layer formed on the first GaN-based semiconductor layer; A second GaN-based semiconductor layer formed on the active layer; A first electrode formed on the first GaN-based semiconductor layer on which the active layer and the second GaN-based semiconductor layer are not formed; And a second electrode formed on the second GaN-based semiconductor layer.

In this case, the thin film is formed of a material having a coefficient of thermal expansion determined by the thickness of the thin film, the process temperature at which the thin film is formed, and the deformation tolerance value of the sapphire substrate.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor light emitting device, including: forming a thin film on a bottom surface of a sapphire substrate; Forming a first GaN-based semiconductor layer on an upper surface of the sapphire substrate; Forming an active layer on the first GaN-based semiconductor layer; And forming a second GaN-based semiconductor layer on the active layer.

를 만족하는 열팽창 계수를 가지는 물질로 형성하고, 여기서, CT는 열팽창 계수를 나타내고, +FD는 상기 사파이어 기판의 +방향 최대 변형 허용 값을 나타내며, -FD는 상기 사파이어 기판의 -방향 최대 변형 허용 값을 나타내고, TH는 상기 박막의 두께를 나타내며,

는 상기 박막이 형성되는 공정온도와 상온과의 차이값을 나타내고, a 내지 h는 미리 정해진 상수 값을 나타내는 것을 특징으로 한다.The thin film is

Is formed of a material having a thermal expansion coefficient that satisfies, wherein CT represents a thermal expansion coefficient, + FD represents a maximum deformation allowable value in the + direction of the sapphire substrate, and -FD represents a maximum deformation allowable value in the -direction of the sapphire substrate. TH represents the thickness of the thin film,

Represents a difference value between a process temperature at which the thin film is formed and a room temperature, and a to h represent a predetermined constant value.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor light emitting device, including: forming a first GaN-based semiconductor layer on an upper surface of a sapphire substrate; Determining whether the sapphire substrate is deformed; If it is determined that the sapphire substrate is deformed, forming a thin film on a lower surface of the sapphire substrate using a predetermined material; Forming an active layer on the first GaN-based semiconductor layer; Forming a second GaN semiconductor layer on the active layer; Etching a portion of the active layer and the second GaN semiconductor layer until the first GaN semiconductor layer is exposed; And forming a first electrode on the first GaN-based semiconductor layer on which the active layer and the second GaN-based semiconductor layer are not formed, and forming a second electrode on the second GaN-based semiconductor layer. .

According to the present invention, in forming a GaN-based semiconductor layer on the upper surface of the sapphire substrate, a GaN-based semiconductor layer and at least one groove are formed on the lower surface of the sapphire substrate by using a material having a smaller coefficient of thermal expansion than the sapphire. The occurrence of deformation of the sapphire substrate due to the difference in thermal expansion coefficient between the sapphire substrates can be prevented, thereby producing a semiconductor light emitting device having excellent characteristics.

1 is a view showing the structure of a semiconductor light emitting device according to a first embodiment of the present invention.
2 is a view showing the temperature curve used in the numerical analysis of the displacement of the substrate according to the change in the coefficient of thermal expansion of the thin film according to the present invention.
3 to 11 is a view showing the numerical results of the displacement of the substrate according to the thermal expansion coefficient change of the thin film according to the present invention.
12 is a view showing the structure of a semiconductor light emitting device according to the second embodiment of the present invention.
13 is a view showing a method of manufacturing a semiconductor light emitting device according to the first embodiment of the present invention.
14 is a view showing a method of manufacturing a semiconductor light emitting device according to the second embodiment of the present invention.
15 is a view showing a method for determining whether the sapphire substrate is deformed according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing the structure of a semiconductor light emitting device according to a first embodiment of the present invention. As shown, the semiconductor light emitting device 100 according to the embodiment of the present invention is a substrate 110, a thin film 112 formed on the lower surface of the substrate 110, N-type GaN semiconductor layer 120, active layer 130 ), A P-type GaN semiconductor layer 140, a transparent electrode layer 150, a P-type electrode 160, and an N-type electrode 170.

Since the substrate 110 has the same crystal structure as that of the GaN-based semiconductor material grown thereon and there is no commercial substrate that forms a lattice match, a sapphire substrate is used in consideration of lattice matching.

The sapphire substrate is a Hexa-Rhombo R3c symmetric crystal with a lattice constant of 13.001Å in the c-axis direction and 4.765Å in the a-axis direction. A (1120) plane, an R (1102) plane, and the like are used.

In the C plane of the sapphire substrate, since the GaN-based semiconductor material is relatively easy to grow and stable at high temperature, the sapphire substrate is mainly used as a substrate for a blue or green light emitting device.

Meanwhile, in the semiconductor light emitting device 100 according to the present invention, thermal expansion coefficients of sapphire (Al ₂ O ₃ ) constituting the substrate 110 and GaN-based semiconductor layers 120 and 140 formed on the substrate 110 are provided. In order to prevent deformation of the substrate 110 due to the difference, a thin film 112 is formed on the lower surface of the substrate 110.

In one embodiment, the thin film 112 is a material having a coefficient of thermal expansion determined in consideration of the process temperature at which the thin film 112 is formed, the deformation allowable displacement of the substrate 110, and the thickness of the thin film 112. Is formed.

Hereinafter, the thermal expansion coefficient of the material used to form the thin film 112 will be described with reference to FIGS. 2 to 11 in which various numerical examples are shown.

Prior to explaining the numerical example, the physical properties and numerical methods of the materials used in the numerical analysis will be briefly described.

First, the properties of the materials used in the numerical analysis are shown in Table 1 below.

In the numerical analysis of the present invention, the finite element model is defined in the axisymmetric manner using the axis symmetry and the analysis is performed. The displacement caused by the temperature difference was calculated through thermal stress analysis, and the displacement in the thickness direction from the center to the edge of the substrate 110 was defined as a result value.

The temperature curve of this numerical analysis is shown in FIG. Here, the initial temperature of Step 1 is defined according to the process temperature of the thin film deposited on the lower surface of the substrate (110). The GaN-based semiconductor layer grows at 1080 ° C. and assumes that the GaN semiconductor layer does not cause deformation of the substrate 110. In this numerical analysis, the final displacement of the substrate 110 was calculated by adding the displacement in Step 1 and the displacement in Step 2.

3 shows that when the diameter of the substrate 110 is 2 inches, when the thin film 112 is formed at a process temperature of 20 ° C., the displacement of the substrate according to the change of the thermal expansion coefficient is determined by the thickness of the thin film 112 (2 μm, 3 μm and 4 μm), and FIG. 4 is a view showing displacement of a substrate according to a change in thermal expansion coefficient for each thickness of the thin film 112 when the thin film 112 is formed at a process temperature of 260 ° C. FIG. 5 is a view showing the displacement of the substrate according to the change of the thermal expansion coefficient for each thickness of the thin film 112 when the thin film 112 is formed at a process temperature of 500 ° C.

In FIG. 3, (a) shows a displacement generated when the substrate 110 having the thin film 112 formed at a process temperature of 20 ° C. is heated to 1080 ° C., which is a growth temperature of a GaN-based semiconductor layer. The GaN-based semiconductor layer is formed on the substrate 110 on which the thin film 112 is not formed and then represents a displacement occurring when cooled to room temperature, and (c) and (d) are displacements of (a) and (b). The graph shows the final displacement of the substrate obtained by adding.

As shown in FIG. 3A, as the coefficient of thermal expansion of the thin film 112 increases from 2.45e-6 / ° C to 9.87e-6 / ° C, the displacement of the substrate 110 approaches zero, and the thermal expansion It can be seen that as the coefficient becomes 9.87e-6 / ° C or more, the displacement of the substrate 110 also increases. In particular, it can be seen that this tendency increases as the thickness of the thin film 112 increases.

On the contrary, it can be seen that the displacement of the substrate 110 according to the coefficient of thermal expansion shown in FIG. 3 (b) tends to be opposite to that shown in FIG. It can be seen that the tendency for is the same as that shown in FIG.

Meanwhile, in FIGS. 3C and 3D, it can be seen that the final displacement of the substrate 110 does not show a significant difference in the thickness of the thin film 112 and the change in the coefficient of thermal expansion. This is because the temperature difference and the cooling temperature difference are the same.

On the other hand, in the case of FIG. 4, when comparing each drawing with each drawing of FIG. 3, it can be seen that the amount of change in displacement of the substrate 110 is greater than the result shown in each drawing of FIG. 3.

In the case of FIG. 5, when compared with the drawings of FIGS. 3 and 4, not only the displacement of the substrate 110 according to the change of the thermal expansion coefficient but also the variation of the displacement of the substrate 110 according to the thickness of the thin film 112 is greatest. It can be seen that.

Based on the above experimental results, the displacement generated when the substrate 110 formed with the thin film 112 at a given process temperature is raised to 1080 ° C, the growth temperature of the GaN-based semiconductor layer (hereinafter referred to as 'first displacement'). It can be defined as shown in Equation 1 below, the displacement generated when the GaN-based semiconductor layer is formed on the substrate 110 in which the thin film 112 is not formed and then cooled to room temperature (hereinafter, 2 displacement 'can be defined as Equation 2.

In Equation 1, TH represents the thickness of the thin film 112, CT represents the coefficient of thermal expansion, the process temperature represents the temperature in the process of forming the thin film 112, the reference temperature is the reference of a predetermined temperature Value (eg, room temperature).

Therefore, since the final displacement (hereinafter, referred to as 'third displacement') of the substrate 110 is the sum of the first displacement and the second displacement, it may be defined as Equation 3 below. It may be defined as in Equation 4.

Next, when the diameter of the substrate 110 is 4 inches, when the thin film 112 is formed at a process temperature of 20 ° C., the displacement of the substrate according to the change in the coefficient of thermal expansion is determined by the thickness of the thin film 112 ( 2 μm, 3 μm, and 4 μm), and FIG. 7 shows the displacement of the substrate by the thickness of the thin film 112 when the thin film 112 is formed at a process temperature of 260 ° C. 8 is a view showing the displacement of the substrate by the thickness of the thin film 112 according to the change in the coefficient of thermal expansion when the thin film 112 is formed at a process temperature of 500 ℃.

6 to FIG. 6, the first displacement may be defined as Equation 5 below, the second displacement may be defined as Equation 6, and the third displacement may be defined as Equation 7 below. And Equation 8 can be defined.

In addition, FIG. 9 illustrates that when the thin film 112 is formed at a process temperature of 20 ° C. when the diameter of the substrate 110 is 6 inches, the displacement of the substrate according to the change in the coefficient of thermal expansion may be measured. Μm, 3 μm, and 4 μm), and FIG. 10 shows the displacement of the substrate according to the change in the coefficient of thermal expansion by the thickness of the thin film 112 when the thin film 112 is formed at a process temperature of 260 ° C. FIG. 11 is a view showing the displacement of the substrate according to the change of the thermal expansion coefficient for each thickness of the thin film 112 when the thin film 112 is formed at a process temperature of 500 ° C.

9 to 11, the first displacement may be defined as Equation 9 below, the second displacement may be defined as Equation 10, and the third displacement may be defined as Equation 10 below. 11 and (12).

On the other hand, after rearranging the function expression of the third displacement defined in the above equation (4) by the equation for the coefficient of thermal expansion (CT), the third displacement is expressed as FD, and the constant value in each equation is represented by the letters a to h), the coefficient of thermal expansion of the material used to form the thin film 112, as shown in Equation 13 below, as a function of the process temperature, thickness, and deformation allowable displacement of the substrate 110. Can be defined as

는 상기 박막(112)이 형성되는 공정온도와 기준온도와의 차이값을 나타내고, a는 -7.69696e3, b는 -0.0307537, c는 7.59885e-2, d는 2.97162e-6, e는 8.4e4, f는 7.33333, g는 -0.75, h는 -0.03522를 나타낸다.In Equation 13, -FD is the maximum displacement value in the-direction of the third displacement and + FD is the maximum displacement value in the + direction of the third displacement, TH represents the thickness of the thin film 112,

Represents a difference between the process temperature and the reference temperature at which the thin film 112 is formed, a is -7.69696e3, b is -0.0307537, c is 7.59885e-2, d is 2.97162e-6, and e is 8.4e4 , f is 7.33333, g is -0.75, and h is -0.03522.

On the other hand, it can be seen that by adjusting only the constant values a to h in Equation 13, the third displacement described in Equations 8 and 12 can also be expressed in the same form as in Equation 13.

As described above, the thermal expansion coefficient of the material used to form the thin film 112 according to the present invention is expressed by the equation (13) using the diameter of the substrate 110, the process temperature of the thin film 112, and the thin film 112. The values calculated by varying the thickness are shown in Table 2 below. In Table 2 below, the maximum displacement value in the -direction of the third displacement is -0.020 mm and the maximum displacement value in the + direction of the third displacement is +0.020 mm.

Referring back to FIG. 1, the semiconductor light emitting device according to the present invention may further include at least one of a buffer layer (not shown) and an undoped semiconductor layer (not shown).

The buffer layer is formed between the substrate 110 and the N-type GaN-based semiconductor layer 120 in order to reduce the lattice constant difference between the substrate 110 and the N-type GaN-based semiconductor layer 120, and the buffer layer is formed of low temperature GaN or AlN. It can be formed using.

The undoped semiconductor layer is formed on the buffer layer and may be formed of GaN. Such an undoped semiconductor layer may be formed, for example, by supplying NH ₃ and trimetalgallium (TMGa) on the buffer layer at a growth temperature of 1100 ° C.

The N-type GaN-based semiconductor layer 120 is formed on the substrate 110. Representative GaN-based semiconductor materials include GaN, AlGaN, InGaN, AlInGaN, and the like. Si may be used as an impurity used for the doping of the N-type GaN-based semiconductor layer 120.

The N-type GaN-based semiconductor layer 120, the organic material described above (Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), or hydride vapor deposition method) It is formed by growing on the substrate 110 using a deposition process such as (Hydride Vapor Phase Epitaxy: HVPE).

The active layer 130 is a layer for emitting light, and is usually formed by growing an InGaN layer as a well and growing an (Al) GaN layer as a barrier layer to form a multi-quantum well structure (MQW). In the blue light emitting diode, multiple quantum well structures such as InGaN / GaN are used, and in the ultraviolet light emitting diode, multiple quantum well structures such as GaN / AlGaN, InAlGaN / InAlGaN, and InGaN / AlGaN are used.

Regarding the improvement of the efficiency of the active layer 130, the semiconductor may be controlled by changing the wavelength of light by changing the composition ratio of In or Al, or by changing the depth of the quantum wells in the active layer 130, the number, thickness, etc. of the active layer 130. Internal quantum efficiency of the light emitting device 100 may be improved.

The active layer 130, like the aforementioned N-type GaN-based semiconductor layer 120, uses an N-type GaN-based semiconductor layer 130 using a deposition process such as organometallic chemical vapor deposition, molecular beam epitaxial growth, or hydride vapor deposition. It can be formed on).

The P-type GaN-based semiconductor layer 140 is formed on the active layer 130. Representative GaN-based semiconductor materials include GaN, AlGaN, InGaN, AlInGaN, and the like as described above. Mg may be used as an impurity used for the doping of the P-type GaN-based semiconductor layer 140.

The P-type GaN-based semiconductor layer 140 is formed by growing the semiconductor material on the active layer 130 using a deposition process such as organometallic chemical vapor deposition, molecular beam epitaxial growth, or hydride vapor deposition. do.

The transparent electrode layer 150 is formed on the P-type GaN-based semiconductor layer 140. The transparent electrode layer 150 is suitable for lowering the contact resistance with the P-type GaN-based semiconductor layer 140 having a relatively high energy band gap, and at the same time has a good light transmittance to emit light generated in the active layer 130 to the top. It is preferably formed of a material.

In general, the transparent electrode layer 150 may mainly use a thin layer of Ni / Au, or may use indium tin oxide (ITO) as a material to secure good light transmittance. The transparent electrode layer 150 may be formed by a deposition method such as chemical vapor deposition (CVD) and an e-beam evaporator, or a process such as sputtering, and ohmic bonding. It may be heat-treated at a temperature of about 400 to 900 ℃ to improve the properties of.

The P-type electrode 160 is formed on the transparent electrode layer 150. In general, the P-type electrode 160 may be formed by a deposition method such as electron beam evaporation or a sputtering process using Au or an alloy containing Au.

The N-type electrode 170 may be formed on the mesa-etched N-type GaN-based semiconductor layer 120 as a single layer or a plurality of layers made of a material selected from the group consisting of Ti, Cr, Al, and Au. have. The N-type electrode 170 may be formed on the N-type GaN-based semiconductor layer 120 by a deposition method such as an electron beam evaporation method or a process such as sputtering.

12 is a view showing the structure of a semiconductor light emitting device according to the second embodiment of the present invention. As shown, the semiconductor light emitting device 200 according to the second embodiment of the present invention has the semiconductor light emitting device according to the first embodiment except that at least one groove 214 is formed in the substrate 210. Since it is the same as the device 100, only the differences will be described below.

As shown in FIG. 12, the semiconductor light emitting device 200 according to the second exemplary embodiment of the present invention includes sapphire constituting the substrate 210 and GaN-based semiconductor layers 220 and 240 formed on the substrate 210. At least one groove 214 is formed on the bottom surface of the substrate 110 to prevent deformation of the substrate 210 due to a difference in thermal expansion of the substrate 110, and the substrate 210 including the at least one groove 214. Is formed on the thin film 212 as a whole.

Through this, it is possible to minimize the occurrence of deformation of the substrate 210.

In the semiconductor light emitting device 200 according to the second embodiment described above, although the thin film 212 is described as being formed on the entire lower surface of the substrate 210 including at least one groove 214, the modified embodiment In the example, the thin film 212 is formed only in a region in which the groove 214 is not formed in the lower surface of the substrate 210, or at least one groove 214 is formed in the lower surface of the substrate 210 and the thin film 212 is formed. May not be formed.

Hereinafter, a method of manufacturing a semiconductor light emitting device according to the present invention will be described with reference to FIGS. 13 and 14.

13A to 13E are views illustrating a method of manufacturing a semiconductor light emitting device according to the first embodiment of the present invention.

First, referring to FIG. 13A, a thin film 112 is formed on the bottom surface of the substrate 110. In this case, the thin film 112 may be formed using a material having a thermal expansion coefficient determined by Equation 13. Since the thermal expansion coefficient has already been described in the part related to the thin film 112 shown in FIG. 1, a detailed description thereof will be omitted.

The thin film 112 may be formed using various methods including a powder metallurgy process, a spray method, or a deposition method.

At this time, the powder metallurgy method is a liquid sintering method (Sol-Gel method), a sintering method using a powder in the solid state (atmospheric sintering method: Perssureless Sinterting), pressure sintering method (Hot Pressing), hydrostatic sintering method (Hot Isostatic Pressing), discharge plasma sintering method (Spark Plasma Sintering) and Microwave Sintering.

In addition, the spray method includes a plasma spray method, a thermal spray method, a laser cladding, an electroforming process, a nano particle deposition system (NPDS), an aerosol deposition, and the like.

In addition, vapor deposition methods include physical vapor deposition (Physical Vapor Deposition), chemical vapor deposition (Chemical Vapor Deposition), laser chemical vapor deposition (LCVD).

As described above, according to the present invention, the thin film 112 is formed on the lower surface of the substrate 110 to prevent deformation of the substrate caused by the formation of the N-type GaN-based semiconductor layer 120 on the substrate 110. .

Meanwhile, in the above-described embodiment, only the thin film 112 is formed on the bottom surface of the substrate 110 in order to prevent the deformation of the substrate 110. However, in the modified embodiment, the deformation of the substrate 110 is performed. To more completely prevent the formation of at least one groove 314 on the lower surface of the substrate 110, as shown in Figure 13b and then the entire surface of the substrate 110 including at least one groove 314 The thin film 112 may be formed.

In this case, the at least one groove 314 is formed by using a mechanical processing such as drilling or milling, by using a chemical processing such as etching or chemical polishing, or by using a photochemical processing such as photo etching. It may be formed using electrochemical processing such as electropolishing, or by electrical processing such as electric discharge machining, electron beam processing, ion processing, plasma arc processing, or optical processing such as laser processing.

In another embodiment, at least one groove 314 may be formed on the bottom surface of the substrate 110 instead of forming the thin film 112 to prevent deformation of the substrate 110.

In the following description, it is assumed that only the thin film 112 is formed on the bottom surface of the substrate 110 in order to prevent deformation of the substrate 110.

Next, as shown in FIG. 13C, an N-type GaN-based semiconductor layer 120 is formed on the substrate 110 having the thin film 112 formed on the lower surface thereof. Although FIG. 13C describes that the N-type GaN-based semiconductor layer 120 is directly formed on the substrate 110, in the modified embodiment, the buffer layer (B) may be formed between the substrate 110 and the N-type GaN-based semiconductor layer 120. At least one layer of not shown) and undoped semiconductors (not shown) may be further formed.

Next, as shown in FIG. 13D, the active layer 130 and the P-type GaN-based semiconductor layer 140 are sequentially formed on the N-type GaN-based semiconductor layer 120, and then the P-type GaN-based semiconductor layer ( The transparent electrode layer 150 is coated on the entire surface of the 140.

Next, as shown in FIG. 13E, Mesa etching is performed to the N-type GaN-based semiconductor layer 120 to form the N-type electrode, and the P-type electrode 160 is disposed on the transparent electrode layer 150. The N-type electrode 170 is formed on the mesa-etched N-type GaN-based semiconductor layer 120.

The substrate 110, a buffer layer (not shown), an undoped semiconductor layer (not shown), an N-type GaN-based semiconductor layer 120, an active layer 130, and a P-type GaN-based semiconductor layer 140, a transparent electrode layer 150, the P-type electrode 160, and the N-type electrode 170 have been described in detail in the above-described description of FIG. 1, and thus detailed descriptions thereof will be omitted.

Finally, although not shown, the substrate is thinned through lapping and polishing, and then separated into individual chips by cutting the semiconductor light emitting device using a laser or diamond.

In the above-described embodiments, the present invention has been described as being applied to a semiconductor light emitting device having a horizontal structure in which the P-type electrode and the N-type electrode are formed on the same plane. The present invention can also be applied to a semiconductor light emitting device having a vertical structure which is formed as follows. Hereinafter, an embodiment in which the present invention is applied to a vertical semiconductor light emitting device will be described with reference to FIG. 14.

14A to 14G are views illustrating a method of manufacturing a semiconductor light emitting device according to the second embodiment of the present invention.

As shown in FIG. 14A, a thin film 512 is formed on a bottom surface of the substrate 510 using a material having a thermal expansion coefficient defined in Equation 11 above. Since the method of forming the thin film 512 on the lower surface of the substrate 510 is the same as the method described with reference to FIG. 13A, a detailed description thereof will be omitted.

Meanwhile, as shown in FIG. 14B, the method of manufacturing the semiconductor light emitting device according to the second exemplary embodiment of the substrate 510 may be performed in order to completely prevent deformation of the substrate 510 as in FIG. 13B. After the at least one groove 514 is formed on the lower surface, the thin film 512 is formed on the entire lower surface of the substrate 510 including the at least one groove 514 or the substrate 510 is not formed. At least one groove 514 may be formed on the bottom surface of

Next, as shown in FIG. 14C, an N-type GaN-based semiconductor layer 520 is formed on the upper surface of the substrate 510.

In this case, a buffer layer (not shown) may be further formed between the substrate 510 and the N-type GaN-based semiconductor layer 520.

Next, as shown in FIG. 14D, the active layer 530 and the P-type GaN-based semiconductor layer 540 are formed on the N-type GaN-based semiconductor layer 520, and the P-type GaN-based semiconductor layer 540 is formed. P-type electrode 550 is formed on the substrate.

Next, as shown in FIG. 14E, the structural support layer 560 is formed on the P-type electrode 550. In this case, the structural support layer 560 may be formed of a material such as metal.

Next, as shown in FIG. 14F, the substrate 500 is removed from the N-type GaN-based semiconductor layer 520 by using a laser lift off (LLO) process, thereby removing the N-type GaN-based semiconductor layer 520. Expose the surface.

Thereafter, as illustrated in FIG. 14G, an N-type electrode 570 is formed on the exposed N-type GaN-based semiconductor layer 520.

In the above-described embodiment, the thin film is formed on the lower surface of the substrate regardless of whether the substrate is deformed. In the modified embodiment, the deformation of the substrate occurs due to the formation of the GaN-based semiconductor layer on the substrate. The thin film may be formed only when it is determined that the substrate is deformed.

In this case, first, the semiconductor layer is formed on the substrate, and then it is determined whether the substrate is deformed. At this time, whether the substrate is deformed may be determined using the method illustrated in FIG. 15.

15 is a view illustrating a method of determining whether a substrate is deformed according to the present invention.

As shown in FIG. 15A, the substrate 110 on which the N-type GaN-based semiconductor layer 120 is formed is placed on the stage 400 capable of determining whether the substrate is deformed, and then, on the surface of the stage 400. Height H1 to first point 410 on the surface of N-type GaN-based semiconductor layer 120 and second point 420 on the surface of N-type GaN-based semiconductor layer 120 at the surface of stage 400. Determine the height H2 to.

At this time, the heights H1 and H2 are determined in the following manner. First, when the substrate 110 on which the N-type GaN-based semiconductor layer 120 is formed on the stage 400 is not seated by using a probe (not shown), the height to the surface of the stage 400 is measured to set a reference value.

Subsequently, the substrate 110 having the N-type GaN-based semiconductor layer 120 formed thereon is seated on the stage 400, and then a height (hereinafter referred to as 'first value') to a first point is measured by using a probe. The difference between the reference value and the first value is determined as H1. In addition, the height up to the second point (hereinafter, referred to as a “second value”) is measured using the probe to determine a difference value between the reference value and the second value as H2.

Based on the determined H1 and H2, if the difference between the height H1 from the surface of the stage 400 to the first point and the height H2 from the second point is greater than or equal to the threshold value, the substrate 110 is deformed.

In this case, as illustrated in FIG. 14B, the first point 410 may be the center on the N-type GaN-based semiconductor layer 120, and the second point 420 may border the N-type GaN-based semiconductor layer 120. It can be one of the points on the area.

According to such an embodiment, the thin film 112 may be formed using a material having a thermal expansion coefficient defined in Equation 11, but in another embodiment, the thin film 112 may be formed by using the thermal expansion coefficient of the sapphire constituting the substrate 110. It may be formed using a material having a small coefficient of thermal expansion and not separating and vaporizing from the substrate 110 at a growth temperature of GaN (eg, approximately 1080 degrees). For example, such materials include GaN, AlN, Si, SiC, Si ₃ N _4, and the like.

In this case, the thickness of the thin film 112 may be calculated using the finite element method, or may be formed to the same thickness as at least one of the GaN-based semiconductor layers 120 and 140 formed on the substrate 110.

Those skilled in the art to which the present invention pertains will understand that the above-described present invention can be implemented in other specific forms without changing the technical spirit or essential features.

Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100, 200: semiconductor light emitting element 110, 210: substrate
112, 212, thin film 120, 220: N-type GaN semiconductor layer
130, 230: active layers 140, 240: P-type GaN semiconductor layer
150, 250: transparent electrode layers 160, 260: P-type electrode
170 and 270: N-type electrode

Claims (19)

A sapphire substrate having at least one groove formed on a bottom surface thereof;
A thin film formed on a lower surface of the sapphire substrate;
A first GaN-based semiconductor layer formed on an upper surface of the sapphire substrate;
An active layer formed on the first GaN-based semiconductor layer;
A second GaN-based semiconductor layer formed on the active layer;
A first electrode formed on the first GaN-based semiconductor layer on which the active layer and the second GaN-based semiconductor layer are not formed; And
A second electrode formed on the second GaN-based semiconductor layer,
The thin film is

Is formed of a material having a thermal expansion coefficient that satisfies, wherein CT represents a thermal expansion coefficient, + FD represents a maximum deformation allowable value in the + direction of the sapphire substrate, and -FD represents a maximum deformation allowable value in the -direction of the sapphire substrate. TH represents the thickness of the thin film,

Is a difference value between a process temperature at which the thin film is formed and a reference temperature, and a to h represent a predetermined constant value. delete delete The method of claim 1, wherein the diameter of the sapphire substrate is 2 inches
If the thickness of the thin film is 2㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying -5.54E-06≤CT≤5.80E-06 or 2.44E-06≤CT≤7.98E-06,
If the thickness of the thin film is 3㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying -3.874E-07≤CT≤7.18E-06 or 4.92E-06≤CT≤8.62E-06,
When the thickness of the thin film is 4㎛, the thin film is formed using a material having a thermal expansion coefficient satisfying 2.19E-06≤CT≤7.86E-06 or 6.17E-06≤CT≤8.93E-06 A semiconductor light emitting device. The method of claim 1, wherein when the diameter of the sapphire substrate is 4 inches,
If the thickness of the thin film is 2㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying -2.88E-06≤CT≤3.35E-06 or 3.59E-06≤CT≤6.66E-06,
If the thickness of the thin film is 3㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying 1.35E-06≤CT≤5.53E-06 or 5.68E-06≤CT≤7.73E-06,
When the thickness of the thin film is 4㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying 3.48E-06≤CT≤6.62E-06 or 6.72E-06≤CT≤8.27E-06 A semiconductor light emitting device. The method of claim 1, wherein when the diameter of the sapphire substrate is 6 inches,
If the thickness of the thin film is 2㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying -2.91E-06≤CT≤3.56E-06 or 3.54E-06≤CT≤6.75E-06,
If the thickness of the thin film is 3㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying 1.33E-06≤CT≤5.66E-06 or 5.64E-06≤CT≤7.78E-06,
When the thickness of the thin film is 4㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying 3.46E-06≤CT≤6.71E-06 or 6.70E-06≤CT≤8.31E-06 A semiconductor light emitting device. delete Forming at least one groove in a bottom surface of the sapphire substrate;
Forming a thin film on a lower surface of the sapphire substrate;
Forming a first GaN-based semiconductor layer on an upper surface of the sapphire substrate;
Forming an active layer on the first GaN-based semiconductor layer; And
Forming a second GaN-based semiconductor layer on the active layer;
In the step of forming the thin film,
The thin film is

Is formed of a material having a thermal expansion coefficient that satisfies, wherein CT represents a thermal expansion coefficient, + FD represents a maximum deformation allowable value in the + direction of the sapphire substrate, and -FD represents a maximum deformation allowable value in the -direction of the sapphire substrate. TH represents the thickness of the thin film,

Represents a difference value between a process temperature at which the thin film is formed and a room temperature, and a to h represent a predetermined constant value. delete The method of claim 8, wherein the diameter of the sapphire substrate is 2 inches
If the target thickness of the thin film is 2㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying -5.54E-06≤CT≤5.80E-06 or 2.44E-06≤CT≤7.98E-06 ,
If the target thickness of the thin film is 3㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying -3.874E-07≤CT≤7.18E-06 or 4.92E-06≤CT≤8.62E-06 ,
When the target thickness of the thin film is 4 μm, the thin film may be formed using a material having a thermal expansion coefficient that satisfies 2.19E-06 ≦ CT ≦ 7.86E-06 or 6.17E-06 ≦ CT ≦ 8.93E-06. The manufacturing method of the semiconductor light emitting element characterized by the above-mentioned. The method of claim 8, wherein when the diameter of the sapphire substrate is 4 inches,
If the target thickness of the thin film is 2㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying -2.88E-06≤CT≤3.35E-06 or 3.59E-06≤CT≤6.66E-06 ,
If the target thickness of the thin film is 3㎛, the thin film is formed using a material having a thermal expansion coefficient satisfying 1.35E-06≤CT≤5.53E-06 or 5.68E-06≤CT≤7.73E-06,
When the target thickness of the thin film is 4 μm, the thin film may be formed using a material having a thermal expansion coefficient that satisfies 3.48E-06 ≦ CT ≦ 6.62E-06 or 6.72E-06 ≦ CT ≦ 8.27E-06. The manufacturing method of the semiconductor light emitting element characterized by the above-mentioned. The method of claim 8, wherein when the diameter of the sapphire substrate is 6 inches,
If the target thickness of the thin film is 2㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying -2.91E-06≤CT≤3.56E-06 or 3.54E-06≤CT≤6.75E-06 ,
If the target thickness of the thin film is 3㎛, the thin film is formed using a material having a coefficient of thermal expansion satisfying 1.33E-06≤CT≤5.66E-06 or 5.64E-06≤CT≤7.78E-06,
When the target thickness of the thin film is 4 μm, the thin film may be formed using a material having a thermal expansion coefficient that satisfies 3.46E-06 ≦ CT ≦ 6.71E-06 or 6.70E-06 ≦ CT ≦ 8.31E-06. The manufacturing method of the semiconductor light emitting element characterized by the above-mentioned. The method of claim 8, after the forming of the second GaN semiconductor layer,
Etching a portion of the active layer and the second GaN semiconductor layer until the first GaN semiconductor layer is exposed; And
And forming a first electrode on the first GaN-based semiconductor layer on which the active layer and the second GaN-based semiconductor layer are not formed, and forming a second electrode on the second GaN-based semiconductor layer. A method of manufacturing a semiconductor light emitting device, characterized in that. The method of claim 8, after the forming of the second GaN semiconductor layer,
Forming a first electrode on the second GaN-based semiconductor layer;
Forming a structural support layer of a metal material on the first electrode;
Separating the sapphire substrate from the first GaN-based semiconductor layer to expose a surface of the first GaN-based semiconductor layer; And
And forming a second electrode on a surface of the exposed first GaN-based semiconductor layer. delete Forming a first GaN-based semiconductor layer on an upper surface of the sapphire substrate;
Determining whether the sapphire substrate is deformed;
If it is determined that the sapphire substrate is deformed, forming a thin film on a lower surface of the sapphire substrate using a predetermined material;
Forming an active layer on the first GaN-based semiconductor layer;
Forming a second GaN semiconductor layer on the active layer;
Etching a portion of the active layer and the second GaN semiconductor layer until the first GaN semiconductor layer is exposed; And
Forming a first electrode on the first GaN-based semiconductor layer on which the active layer and the second GaN-based semiconductor layer are not formed, and forming a second electrode on the second GaN-based semiconductor layer,
The determination of whether the sapphire substrate is deformed may include determining a height from a surface of the stage on which the sapphire substrate on which the first GaN-based semiconductor layer is formed to the first point of the surface of the first GaN-based semiconductor layer and the first surface on the stage surface. 1. The method of manufacturing a semiconductor light emitting device according to claim 1, wherein the sapphire substrate is determined to be deformed when a difference in height to a second point on the surface of the GaN-based semiconductor layer is greater than or equal to a threshold. 17. The method of claim 16,
The thin film is a method of manufacturing a semiconductor light emitting device, characterized in that the thermal expansion coefficient is formed of a material smaller than the thermal expansion coefficient of sapphire. delete The method of claim 16, wherein after determining whether the sapphire substrate is deformed,
And forming at least one groove in the lower surface of the sapphire substrate.

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