KR102330026B1 - Semiconductor device - Google Patents

Abstract

An embodiment includes a substrate; a semiconductor structure disposed on the substrate and including a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer; a first electrode disposed on the first conductivity-type semiconductor layer; and a second electrode disposed on the second conductivity type semiconductor layer, wherein at least one of the first electrode and the second electrode is disposed on the first conductivity type semiconductor layer or the second conductivity type semiconductor layer bonding layer to be; a reflective layer disposed on the bonding layer; a capping layer disposed on the reflective layer; and a bonding layer disposed on the capping layer, wherein the capping layer is alternately stacked with a first layer and a second layer at least once, the first layer comprising Ti, and the first layer and a ratio of the thickness of the second layer is from 4:7 to 20:3.

Description

Semiconductor device {SEMICONDUCTOR DEVICE}

The embodiment relates to a semiconductor device.

A semiconductor device including a compound such as GaN or AlGaN has many advantages, such as having a wide and easily adjustable band gap energy, and thus can be used in various ways as a light emitting device, a light receiving device, and various diodes.

In particular, light emitting devices such as light emitting diodes or laser diodes using group 3-5 or group 2-6 compound semiconductor materials of semiconductors have developed red, green, and Various colors such as blue and ultraviolet light can be realized, and efficient white light can be realized by using fluorescent materials or combining colors. , safety and environmental friendliness.

In addition, when a light receiving device such as a photodetector or a solar cell is manufactured using a semiconductor group 3-5 or group 2-6 compound semiconductor material, a photocurrent is generated by absorbing light in various wavelength ranges through the development of the device material. This makes it possible to use light of various wavelength ranges from gamma rays to radio wavelengths. In addition, it has advantages of fast response speed, safety, environmental friendliness, and easy adjustment of device materials, so it can be easily used for power control or ultra-high frequency circuits or communication modules.

Therefore, the semiconductor device can replace a light emitting diode backlight, a fluorescent lamp or an incandescent light bulb that replaces a cold cathode fluorescence lamp (CCFL) constituting a transmission module of an optical communication means and a backlight of a liquid crystal display (LCD) display device. The application is expanding to white light emitting diode lighting devices, automobile headlights and traffic lights, and sensors that detect gas or fire. In addition, the application of the semiconductor device may be extended to high-frequency application circuits, other power control devices, and communication modules.

In a semiconductor device, a rate of change of an operating voltage with time may increase under conditions of high current and high temperature. Accordingly, the cause and a method for solving the cause are being discussed.

The embodiment provides a semiconductor device with improved reliability.

The problem to be solved in the embodiment is not limited thereto, and it will be said that the purpose or effect that can be grasped from the solving means or embodiment of the problem described below is also included.

A semiconductor device according to an embodiment of the present invention includes: a substrate; a semiconductor structure disposed on the substrate and including a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer; a first electrode disposed on the first conductivity-type semiconductor layer; and a second electrode disposed on the second conductivity type semiconductor layer, wherein at least one of the first electrode and the second electrode is disposed on the first conductivity type semiconductor layer or the second conductivity type semiconductor layer bonding layer to be; a reflective layer disposed on the bonding layer; a capping layer disposed on the reflective layer; and a bonding layer disposed on the capping layer, wherein the capping layer is alternately stacked with a first layer and a second layer at least once, the first layer comprising Ti, and the first layer and a ratio of the thickness of the second layer is in a range of 4:7 to 20:3, so that a peeling phenomenon between the semiconductor structure and the bonding layer may be improved.

According to an embodiment, by changing the structure of the electrode of the semiconductor device, reliability under severe conditions of high current and high temperature may be improved.

Various and advantageous advantages and effects of the present invention are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention.

1 is a perspective view of a semiconductor device according to an embodiment of the present invention.
2 is a plan view of a semiconductor device according to an embodiment of the present invention.
3 is a cross-sectional view taken along line I-I' of FIG. 1 .
4 is a conceptual diagram of a first electrode of a semiconductor device according to an embodiment of the present invention.
5 is a graph illustrating internal stress according to thicknesses of a first layer and a second layer among the capping layers of the first electrode.
6 is a graph showing the ohmic characteristics of the electrode according to various modifications.
7 is a graph showing reflectance of an electrode according to various modifications.
8A to 8E are graphs illustrating a change rate of a VF1 value of a semiconductor device according to various deformations of an electrode.
9A to 9E are graphs illustrating a change rate of a VF3 value of a semiconductor device according to various deformations of an electrode.
10A to 10E show emission distributions of semiconductor devices according to various deformations of electrodes.
11A to 11E are photographs of appearances of semiconductor devices according to various deformations of electrodes.
12A to 12E are photographs taken in detail of the exterior features of FIGS. 11A to 11E .
13A to 13E are photographs of cross-sections of electrodes according to various modifications.
14A to 14E are observations of whether the electrode peeling phenomenon occurs according to various deformations.
15A to 15E are observations of whether an electrode peeling phenomenon occurs according to various deformations.

The present embodiments may be modified in other forms or various embodiments may be combined with each other, and the scope of the present invention is not limited to each of the embodiments described below.

Even if a matter described in a specific embodiment is not described in another embodiment, it may be understood as a description related to another embodiment unless a description contradicts or contradicts the matter in another embodiment.

For example, if a specific embodiment describes a feature for configuration A and another embodiment describes a feature for configuration B, the opposite or contradictory description is not explicitly described in an embodiment in which configuration A and configuration B are combined. Unless otherwise indicated, it should be understood as belonging to the scope of the present invention.

In the description of the embodiment, in the case where one element is described as being formed on "on or under" of another element, on (above) or below (on) or under) includes both elements in which two elements are in direct contact with each other or one or more other elements are disposed between the two elements indirectly. In addition, when expressed as "up (up) or down (on or under)", it may include the meaning of not only an upward direction but also a downward direction based on one element.

The semiconductor device may include various electronic devices such as a light emitting device and a light receiving device, and both the light emitting device and the light receiving device may include a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer.

The semiconductor device according to the present embodiment may be a light emitting device.

The light emitting device emits light by recombination of electrons and holes, and the wavelength of this light is determined by the material's inherent energy bandgap. Accordingly, the emitted light may vary depending on the composition of the material.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art to which the present invention pertains can easily implement them.

1 is a perspective view of a semiconductor device according to an embodiment of the present invention. 2 is a plan view of a semiconductor device according to an embodiment of the present invention. 3 is a cross-sectional view taken along line I-I' of FIG. 1 .

1 to 3 , a semiconductor device 100 according to an embodiment of the present invention includes a substrate 110 , a semiconductor structure 120 , a current blocking layer 130 , an ohmic layer 140 , and a first electrode ( 150 ) and a second electrode 160 .

The substrate 110 may include a light-transmitting, conductive, or insulating substrate. The substrate 110 may be a material suitable for semiconductor material growth or a carrier wafer. The substrate 110 may be formed of a material selected from among sapphire (Al2O3), SiC, Si, GaAs, GaN, ZnO, Si, GaP, InP, Ge, and Ga2O3, but the present invention is not limited thereto. The upper surface of the substrate 110 may include a concave-convex structure to improve light extraction efficiency.

Meanwhile, a buffer layer (not shown) for reducing a difference in lattice constants may be further disposed between the substrate 110 and the semiconductor structure 120 .

The semiconductor structure 120 may be disposed on the substrate 110 . In the semiconductor structure 120 , a first conductivity type semiconductor layer 121 , an active layer 123 , and a second conductivity type semiconductor layer 122 may be sequentially disposed.

The first conductivity type semiconductor layer 121 may be implemented with a compound semiconductor such as -V group or -VI group, and may be doped with a first dopant. The first conductivity type semiconductor layer 121 is _{a semiconductor material having a composition formula of In x1} Al _y1 Ga _{1 -x1-y1} N (0≤x1≤1, 0≤y1≤1, 0≤x1+y1≤1), e.g. For example, it may be selected from GaN, AlGaN, InGaN, InAlGaN, and the like. In addition, the first dopant may be an n-type dopant such as Si, Ge, Sn, Se, or Te. When the first dopant is an n-type dopant, the first conductivity-type semiconductor layer 121 doped with the first dopant may be a semiconductor layer including an n-type dopant.

The active layer 123 may be disposed between the first conductivity type semiconductor layer 121 and the second conductivity type semiconductor layer 122 . The active layer 123 is a layer in which electrons (or holes) injected through the first conductivity type semiconductor layer 121 and holes (or electrons) injected through the second conductivity type semiconductor layer 122 meet. The active layer 123 may transition to a low energy level as electrons and holes recombine, and may generate light having a wavelength of visible light or ultraviolet light.

The active layer 123 includes a well layer and a barrier layer, and has any one of a single well structure, a multi well structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum dot structure, or a quantum wire structure. may have, and the structure of the active layer 123 is not limited thereto.

The second conductivity type semiconductor layer 122 may be disposed on the active layer 123 . The second conductivity type semiconductor layer 122 may be implemented with a compound semiconductor such as group III-V or group II-VI, and may be doped with a second dopant. The second conductivity type semiconductor layer 122 is _{a semiconductor material having a composition formula of In x5} Al _y2 Ga _{1 -x5- y2} N (0≤x5≤1, 0≤y2≤1, 0≤x5+y2≤1) or AlInN , AlGaAs, GaP, GaAs, GaAsP, may be formed of a material selected from AlGaInP. The second dopant may be a p-type dopant such as Mg, Zn, Ca, Sr, Ba, or the like. When the second dopant is a p-type dopant, the second conductivity-type semiconductor layer 122 doped with the second dopant may be a semiconductor layer including a p-type dopant.

However, the present invention is not limited thereto, and the first conductivity-type semiconductor layer may be a semiconductor layer including an n-type dopant, and the second conductivity-type semiconductor layer may be a semiconductor layer including a p-type dopant.

A current blocking layer (CBL) 130 may be disposed on the second conductivity type semiconductor layer 122 . Specifically, the current blocking layer 130 may be disposed in a region of the second conductivity type semiconductor layer 122 in which a second electrode 160 to be described later will be disposed. That is, the current blocking layer 130 may be disposed between the second electrode 160 and the second conductivity-type semiconductor layer 122 . Also, the current blocking layer 130 may overlap the second electrode 160 in a vertical direction (Z-axis direction). The current blocking layer 130 may improve the luminous efficiency of the light emitting device by alleviating the current concentration phenomenon.

The current blocking layer 130 may include a material having electrical insulation or forming a Schottky contact. The current blocking layer 130 may be formed of oxide, nitride, or metal. Exemplarily, the current blocking layer 130 may _{include at least one of SiO 2} , SiOx, SiOxNy, Si ₃ N ₄ , Al ₂ O ₃ , TiOx, Ti, Al, and Cr. The current blocking layer 130 may be omitted in some cases.

The ohmic layer 140 may be disposed on the second conductivity type semiconductor layer 122 and the current blocking layer 130 . The ohmic layer 140 may be formed of a material having high light transmittance to increase light extraction efficiency. The ohmic layer 140 may be omitted in some cases.

The ohmic layer 140 includes indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), and indium gallium tin oxide (IGTO). ), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), ZnO, IrOx, RuOx , NiO, RuOx/ITO, Ni/IrOx/Au, or Ni/IrOx/Au/ITO, Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Sn, In, Ru, Mg, Zn, Pt, It may be formed including at least one of Au and Hf, but is not limited to these materials.

Meanwhile, the semiconductor structure 120 may include a recess M formed by mesa etching. That is, a recess M may be formed in a region of the semiconductor structure 120 in which the first electrode 150 to be described later will be disposed. The recess may extend through the second conductivity type semiconductor layer and the active layer to a partial region of the first conductivity type semiconductor layer 121 . The recess M may be formed by mesa etching after the formation of the semiconductor structure 120 , the current blocking layer 130 , and the ohmic layer 140 .

The first electrode 150 may be disposed on the first conductivity type semiconductor layer 121 . Specifically, the first electrode 150 may be disposed on a partial region of the first conductivity-type semiconductor layer 121 exposed by the recess M. The first electrode 150 may include a first pad electrode 150a and a plurality of first branch electrodes 150b.

The first pad electrode 150a may be a region to which a wire is bonded. The first pad electrode 150a may have a larger area than the first branch electrode 150b for wire bonding. Specifically, the first pad electrode 150a may have a wider width in the X-axis direction than the first branch electrode 150b. However, the shape of the first pad electrode 150a is not particularly limited.

The first branch electrode 150b may extend from the first pad electrode 150a. The first branch electrode 150b may extend from the first pad electrode 150a toward the second pad electrode 160a. In this case, the first branch electrode 150b may have a longer length in the Y-axis direction than the first pad electrode 150a. Accordingly, current injection efficiency and current dispersion efficiency of the semiconductor device 100 may be improved by the first branch electrode 150b, thereby improving luminous efficiency.

In particular, the first branch electrodes 150b may be disposed on both sides of the semiconductor structure 120 with respect to a center line parallel to the Y-axis direction. Also, each of the first branch electrodes 150b may be disposed between the second branch electrodes 160b spaced apart from each other. Accordingly, the current may be uniformly distributed by the first branch electrode 150b. Meanwhile, although two first branch electrodes 150b are illustrated in FIGS. 1 and 2 , the present invention is not limited thereto.

The second electrode 160 may be disposed on the second conductivity-type semiconductor layer 122 . Specifically, the second electrode 160 may be disposed in a region of the ohmic layer 140 that vertically overlaps with the current blocking layer 130 . The second electrode 160 may include a second pad electrode 160a and a plurality of second branch electrodes 160b.

The second pad electrode 160a may be a region to which a wire is bonded. The second pad electrode 160a may have a larger area than the second branch electrode 160b for wire bonding. Specifically, the second pad electrode 160a may have a wider width in the X-axis direction than the second branch electrode 160b. However, the shape of the second pad electrode 160a is not particularly limited.

The second branch electrode 160b may extend from the second pad electrode 160a. The second branch electrode 160b may extend from the second pad electrode 160a toward the first pad electrode 150a. In this case, the second branch electrode 160b may have a longer length in the Y-axis direction than the second pad electrode 160a. Accordingly, current injection efficiency and current dissipation efficiency of the semiconductor device 100 may be improved by the second branch electrode 160b, so that luminous efficiency may be improved.

In particular, the second branch electrode 160b may be disposed on a center line parallel to the Y-axis direction of the semiconductor structure 120 . In addition, the second branch electrodes 160b may be disposed one at each side with respect to a center line parallel to the Y-axis direction. Specifically, the second branch electrode 160b and the first branch electrode 150b may be alternately disposed one by one. In this case, the number of the second branch electrodes 160b may be greater than the number of the first branch electrodes 150b. By increasing the number of the second branch electrodes 160b, hole injection efficiency may be further improved. Although three second branch electrodes 160b are illustrated in FIGS. 1 and 2 , the present invention is not limited thereto.

Meanwhile, in FIG. 3 , the first electrode 150 is disposed to have a relatively short length compared to FIGS. 1 and 2 . However, substantially the first electrode 150 illustrated in FIG. 3 may be the first pad electrode 150a. That is, only the first pad electrode 150a among the first electrodes 150 may be shown in the cross-sectional view.

Also, the second electrode 160 illustrated in FIG. 3 may substantially include a second pad electrode 160a and a second branch electrode 160b. That is, since the second pad electrode 160a and the second branch electrode 160b are disposed to have a predetermined thickness, they may be viewed as one configuration in a cross-sectional view.

In addition, the current blocking layer 130 may be disposed in a region corresponding to the second electrode 160 . Accordingly, as shown in FIG. 3 , the current blocking layer 130 may vertically (Z-axis direction) overlap both the second pad electrode 160a and the second branch electrode 160b of the second electrode 160 . can In addition, although not shown, the current blocking layer 130 may be disposed under the second branch electrodes (refer to FIGS. 1 and 2 ) disposed above and below the second branch electrode disposed in the central portion of the semiconductor device 100 . have.

The first electrode 150 and the second electrode 160 may include a plurality of layers. Specifically, the first and second electrodes 150 and 160 may include a bonding layer, a reflective layer, a diffusion barrier layer, and a bonding layer. can This structure may be equally applied to the pad electrodes 150a and 160a and the branch electrodes 150b and 160b of the first and second electrodes 150 and 160 . This will be described later.

4 is a conceptual diagram of a first electrode of a semiconductor device according to an embodiment of the present invention. 5 is a graph illustrating internal stress according to thicknesses of a first layer and a second layer among the capping layers of the first electrode.

Referring to FIG. 4 , the first electrode 150 may include a bonding layer 151 , a reflective layer 152 , a capping layer 153 , and a bonding layer 154 . Meanwhile, although only the first electrode 150 is illustrated in the drawing, the same may be applied to the second electrode 160 . Also, the same may be applied to the pad electrodes 150a and 160a and the branch electrodes 150b and 160b of each of the first and second electrodes 150 and 160 .

The bonding layer 151 may be disposed on a partial region of the first conductivity-type semiconductor layer 121 exposed by the recess M. The bonding layer 151 may easily bond the first conductivity-type semiconductor layer 121 and the electrode 150 . That is, the bonding layer 151 may improve bonding strength between the first conductivity type semiconductor layer 121 and the reflective layer 152 . In addition, the bonding layer 151 may improve the ohmic characteristics of the first conductivity type semiconductor layer 121 . The bonding layer 151 may include Cr.

The reflective layer 152 may be disposed on the bonding layer 151 . The reflective layer 152 may be made of a material having excellent reflectivity. For example, the reflective layer 152 may include at least one selected from Al, Ag, Rh, Cu, Re, Bi, Al, Zn, W, Sn, In, and Ni, or an alloy thereof. The reflective layer 152 may improve light output by reflecting light emitted from the active layer 123 .

The capping layer 153 may be disposed on the reflective layer 152 . The capping layer 153 may be a barrier layer that prevents diffusion of materials included in the reflective layer 152 and the bonding layer 154 . The capping layer 153 may include a plurality of layers. That is, the capping layer 153 may have a structure in which the first layers 153a-n, n≧1 and the second layers 153b-n, n≧1 are alternately stacked at least once. Hereinafter, for convenience, the plurality of first and second layers may be referred to as 153a and 153b, respectively. Since the capping layer 153 has a structure in which a plurality of layers are stacked, internal stress in the capping layer 153 may be relieved.

The first layers 153a - n may be disposed on the reflective layer 152 . Also, the second layer 153b-n may be disposed on the first layer 153a-n. In this case, the first first layer on the reflective layer 152 may be defined as a 1-1 layer 153a-1. And the closer to the bonding layer 154, the first 1-2 layers (not shown), 1-3 layers (not shown), . . . It may be defined as the 1-nth layer (153a-n, n≥1). Also, the first second layer on the 1-1 layer 153a-1 may be defined as the 2-1 layer 153b-1. And as it approaches the bonding layer 154, the 2nd-2nd layer (not shown), the 2-3th layer (not shown), ... It may be defined as the 2-nth layer (153b-n, n≥1).

The first layer 153a may include Ti. The second layer 153b may include any one selected from Ni and Pt, and more preferably include Ni. By stacking a plurality of the first layer 153a and the second layer 153b including different materials, the internal stress of the capping layer 153 may be relieved. Accordingly, it is possible to prevent the electrode from peeling off due to the internal stress of the capping layer.

For example, the first layer 153a and the second layer 153b may have opposite internal stresses. That is, if the internal stress of the first layer 153a is a compressive stress, the internal stress of the second layer 153b may be a tensile stress. The reverse is also possible, without limiting the type of internal stress here. Since the first and second layers 153a and 153b have opposite internal stresses, the internal stress of the capping layer 153 may be offset. Meanwhile, the fact that the first layer 153a and the second layer 153b have opposite internal stresses is only an example for carrying out the present invention, and the present invention is not limited thereto.

A ratio of the thicknesses of the first layer 153a and the second layer 153b may be 4:7 to 20:3. Preferably, the ratio of the thicknesses of the first layer 153a and the second layer 153b may be 9:7 to 20:3. Also, the first layer 153a may be formed to be thicker than the second layer 153b. When the ratio of the thicknesses of the first and second layers 153a and 153b is out of the above range, the internal stress of any one layer may be relatively high. Accordingly, the effect of relieving the internal stress, which is opposite to each other, is insignificant, and thus the electrode may be peeled off.

Meanwhile, the thickness of the first layer 153a may be 20 to 100 nm. Also, when the second layer 153b includes Ni, the thickness of the second layer 153b may be 35 nm or less. Here, among the capping layers 153 , the second layer 153b may play a stronger role as a barrier layer than the first layer 153a. In this case, the minimum thickness of the second layer 153b may be 15 nm. Accordingly, more preferably, the thickness of the second layer 153b may be 15 to 35 nm. However, even if the second layer 153b is smaller than 15 nm, the capping layer 153 may act as a barrier layer if the thickness of the first layer 153a is sufficiently thick.

In particular, referring to FIG. 5 , in the case of Ti, the internal stress may have 0 or a negative value in the range of 20 to 100 nm. In addition, in the case of Ni, the internal stress has a positive value, and as the thickness increases, the internal stress may increase. Accordingly, as shown in FIG. 5 , in a section in which Ti and Ni have opposite stresses, the internal stress between the first layer 153a and the second layer 153b may be offset. And as shown in FIG. 4 , the stress acting on the reflective layer 152 bonded to the capping layer 153 is directed to the side, thereby preventing the peeling phenomenon between the electrode and the semiconductor structure 120 or between the electrode and the ohmic layer 140 . can be prevented

That is, when the first layer 153a and the second layer 153b have the same type of internal stress, deformation may occur in the capping layer 153 under high current and high temperature conditions. In addition, this deformation may also occur in the reflective layer 152 bonded to the capping layer 153 . That is, the reflective layer 152 may receive a lifting force upward due to the deformation of the capping layer 153 . As a result, the electrode 150 is lifted from the first conductivity-type semiconductor layer 121 , and thus the operating voltage is increased, thereby reducing the reliability of the semiconductor device 100 . In addition, this peeling phenomenon may also occur between the electrode 160 and the second conductivity type semiconductor layer 122 .

However, when the first layer 153a has an internal stress opposite to that of the second layer 153b, the internal stress in the capping layer 153 is canceled and deformation may be minimized. In addition, a force toward the side may act on the reflective layer 152 bonded to the capping layer 153 . As a result, deformation of the reflective layer 152 bonded to the capping layer 153 is also minimized, thereby preventing the electrode from peeling off and improving the reliability of the semiconductor device.

On the other hand, when Ti is 20 nm or 100 nm, the internal stress 0 may be the minimum internal stress. In addition, when Ti is 45 nm, the internal stress of -1.4×10 ^-14 d/cm may be the maximum internal stress. Here, the reason that the maximum internal stress has a negative value is because it is a stress acting in a direction opposite to that of Ni.

On the other hand, in the case of Ni of FIG. 5, it may have a stress value as in Equation 1. Here, S may mean internal stress (dynes/cm), and T may mean thickness (cm).

And according to the experimental results to be described later, when the first layers 153a and Ti are 100 nm and the second layers 153b and Ni are 15 nm, the delamination of the electrode 150 can be prevented. In this case, the internal stress of the first layer 153a may be approximately 0 (see FIG. 5 ). Also, according to Equation 1, the internal stress of the second layer 153b ^{may be 1.6×10 −14} d/cm.

That is, when the internal stress of the second layer 153b is 1.6×10 ⁻¹⁴ d/cm, the peeling phenomenon of the electrode may be prevented even if the first layer 153a does not have the opposite internal stress. In other words, the internal stress of the first and second layers 153a and 153b is not canceled, and even if the second layer 153b ^{has an internal stress of 1.6×10 -14} d/cm, the electrode peeling phenomenon will not occur. can ^{Accordingly, the sum of 0, which is the internal stress of the first layer 153a, and 1.6×10 -14} d/cm, which is the internal stress of the second layer 153b, is equal to the value of the first layer 153a and the second layer 153b. It may be the maximum allowable internal stress value (A). That is, the maximum internal stress value A of the capping layer 153 ^{may be 1.6×10 −14} d/cm.

Meanwhile, the maximum internal stress of the first layer 153a ^{may be -1.4×10 −14} d/cm ( FIG. 5 ). When the first layer 153a has a maximum internal stress, the second layer 153b having a stress opposite to that of the first layer 153a may also have a maximum internal stress. Also, at this time, the sum of the maximum internal stresses of the first layer 153a and the second layer 153b may be 1.6×10 ⁻¹⁴ d/cm (maximum allowable internal stress value A). Accordingly, when the first layer 153a has a maximum internal stress of -1.4×10 ⁻¹⁴ d/cm, the maximum internal stress of the second layer 153b ^{may be 3.0×10 −14} d/cm. And when the second layer 153b has the maximum internal stress, the thickness of the second layer 153b may be approximately 3.5×10 ⁻⁶ cm (35 nm).

As described above, the thickness of the first layer 153a may be 20 to 100 nm. When the thickness of the first layer 153a is less than 20 nm, the first and second layers 153a and 153b have the same internal stress, so that the electrode may be peeled off. In addition, when the thickness of the first layer 153a is greater than 100 nm, the first and second layers 153a and 153b have the same internal stress, so that the electrode may be peeled off.

The thickness of the second layer 153b may be 15 to 35 nm. When the thickness of the second layer 153b is less than 15 nm, the thickness is too thin, and the role of the barrier layer between the reflective layer 152 and the bonding layer 154 may be insignificant. When the thickness of the second layer 153b is greater than 35 m, the internal stress becomes too large, so that the offsetting effect with the internal stress of the first layer 153a is insignificant, and the electrode may be peeled off.

On the other hand, the internal stress value according to Equation 1 and the thickness according to FIG. 5 is only an example for the practice of the present invention, and the present invention is not limited thereto.

The bonding layer 154 may be disposed on the capping layer 153 . The bonding layer 154 may be a layer for wire bonding. For example, the bonding layer 154 may be any one selected from Au, Ag, or an alloy thereof, but the present invention is not limited thereto.

[Experimental example]

Hereinafter, an experimental example of a semiconductor device to which electrodes having various structures is applied will be described with reference to FIGS. 6 to 15E . Specifically, Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1 and Example 2 were constructed to compare ohmic characteristics, reflectance, operating voltage, emission distribution, appearance characteristics, and peeling phenomenon.

Table 1 shows the structures of the electrodes of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1 and Example 2. Meanwhile, the structure of the electrode is the same for both the first electrode and the second electrode, and the same may be applied to the pad electrode and the branch electrode of each electrode.

bonding layer reflective layer capping layer bonding layer etc Comparative Example 1 Cr Al Ni Au - Comparative Example 2 Cr Al Ni Au SiO2 passivation Comparative Example 3 Cr Al Ti/Ru/Cr/Pt Au Step difference between Ti/Ru and Cr/Pt Example 1 Cr Al Ti/Ni/Ti/Ni/Ti Au - Example 2 Cr Al Ti/Pt/Ti/Pt/Ti/Pt Au -

Referring to Table 1, in Comparative Examples 1-3 and Examples 1 and 2, the bonding layer 151, the reflective layer 152, and the bonding layer 154 may be made of the same material. That is, the respective layers of the electrode 150 may be formed similarly in addition to the structure of the capping layer 153 .

Here, the thickness of the bonding layer 151 and the bonding layer 154 of Comparative Examples 1-3 and Examples 1 and 2 may be the same. In addition, the thickness of the reflective layer 152 of Comparative Examples 1-3 and Examples 1 and 2 may be 300 or 360 nm. In the case of the reflective layer 152 including Al, it may have a reflectance of a similar level in general at a thickness of 300 to 360 nm.

Meanwhile, in Comparative Example 2, a passivation layer of SiO 2 may be formed on the same electrode as in Comparative Example 1. In addition, in Comparative Example 3, a step (see FIG. 13C ) may be formed in the middle (between Ti/Ru and Cr/Pt) of the capping layer 153 . That is, the width (length in the direction perpendicular to the height direction) of Cr/Al/Ti/Ru may be greater than the width of Cr/Pt/Au.

Examples 1 and 2 may be electrodes according to the above-described embodiments of the present invention. Specifically, Example 1 had a structure of a first layer/second layer/first layer/second layer/first layer, wherein the first layer contained Ti and the second layer contained Ni. can do. Also, the first layer 153a may have a thickness of 100 nm, and the second layer 153b may have a thickness of 15 nm. Example 2 had a structure of 1st layer / 2nd layer / 1st layer / 2nd layer / 1st layer / 2nd layer, In this case, the 1st layer contains Ti, and the 2nd layer contains Pt. may include Also, the first layer may have a thickness of 100 nm, and the second layer may have a thickness of 50 nm.

Table 2 compares the sheet resistance and reflectance of Comparative Examples 1 and 3 and Examples 1 and 2;

Cr/Al/Ni/Au
(Comparative Example 1) Cr/Al/Ti/Ru
(Comparative Example 3-1) Cr/Pt/Au
(Comparative Example 3-2) Cr/Al/
Ti/Ni/Ti/Ni/Ti/Au
(Example 1) Cr/Al/
(Ti/Pt)×3/Au
(Example 2) Sheet resistance (mΩ/sq.) 11.4 106.5 13.0 7.0 - 11.0 12.0 reflectivity(%) 71.7 - 39.8 - -

Here, in the case of Comparative Example 3, the lower layer (Cr/Al/Ti/Ru) (Comparative Example 3-1) and the upper layer (Cr/Pt/Au) (Comparative Example 3-2) having a step difference were separately separated, respectively, and the sheet resistance and reflectance were measured. In addition, in the case of reflectance, the reflectance was measured only in Comparative Example 1 because the reflective layer 152 was formed of the same material having a similar level of thickness.

It can be seen that the sheet resistance is almost at the same level except for the lower layer of Comparative Example 3. In addition, the reflectance may have almost the same level except for the upper layer of Comparative Example 3.

6 is a graph illustrating ohmic characteristics of a semiconductor device according to various deformations of electrodes. 7 is a graph showing reflectance of a semiconductor device according to various deformations of an electrode. Meanwhile, Comparative Examples 3-3 and 3-4 disclosed in FIGS. 6 and 7 may be obtained by separating the aforementioned Comparative Example 3 into another structure. That is, Comparative Example 3-3 may have a structure of Cr/Al/Ti, and Comparative Example 3-4 may have a structure of Ti/Ru/Cr/Pt/Au.

Referring to FIG. 6 , it can be seen that Comparative Examples 1 and 3 and Examples 1 and 2 as well as other structures have similar resistance values. Also, referring to FIG. 7 , when the Al reflective layer has a thickness of 300 or 360 nm, it can be seen that the electrode has a similar level of reflectance (70 to 80%). In addition, it can be seen that when the Al reflective layer is not present, the reflectance is significantly lower than that in the case where the Al reflective layer is present.

That is, when Table 2 and FIGS. 6 and 7 are taken together, it can be seen that the electrode according to the embodiment of the present invention is at the same level as the conventional electrode in its characteristics.

8A to 8E are graphs illustrating a change rate of a VF1 value of a semiconductor device according to various deformations of an electrode. 9A to 9E are graphs illustrating a change rate of a VF3 value of a semiconductor device according to various deformations of an electrode. 8A to 8E show the characteristics of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1 and Example 2 in that order, and FIGS. 9A to 9E are sequentially Comparative Example 1, Comparative Example 2, and Comparative The characteristics of Example 3, Example 1 and Example 2 are shown.

VF1 and VF3 may mean forward operating voltages when forward current is supplied. In addition, ΔVF1 and ΔVF3 may mean a change rate of an operating voltage with time. ΔVF1 was measured at 90A/cm ² , 1 μA, and ΔVF3 was measured at 90 A/cm ² , 95 mA. In addition, ΔVF1 and ΔVF3 were measured at 0, 24, 96, and 168 hours, respectively. In addition, each of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1, and Example 2 was measured by inputting a total of 10 samples.

As the change rates of VF1 and VF3 increase, it may mean that the change of the operating voltage is large. Therefore, it may be desirable in terms of reliability to maintain a constant level of ΔVF1 and ΔVF3. In particular, in the case of ΔVF1, it is preferable to be within ±3% in terms of reliability, and in the case of ΔVF3, it may be preferable to be within ±0.06V in terms of reliability. In particular, in the case of ΔVF3, since the semiconductor device operates at a high current, heat generation of the semiconductor device may occur. Therefore, it is possible to judge the reliability of the semiconductor device under severe conditions of high temperature and high current based on the measurement result of ΔVF3.

In the case of Comparative Example 1, it can be seen that ΔVF1 ( FIG. 8A ) maintains a constant level, but ΔVF3 ( FIG. 9A ) rapidly increases (maximum 0.18V). In the case of Comparative Example 2, it can be seen that ΔVF1 (Fig. 8b) tends to slightly decrease (maximum -3.5%), and ΔVF3 (Fig. 9b) slightly increases (maximum +0.07V). In Comparative Example 3, it can be seen that ΔVF1 (FIG. 8c) tends to decrease sharply (up to -6.5%), but ΔVF3 (FIG. 9c) maintains a constant level. In the case of Example 1, it can be seen that both ΔVF1 ( FIG. 8D ) and ΔVF3 ( FIG. 9D ) maintain a constant level. In the case of Example 2, it can be seen that ΔVF1 (Fig. 8e) tends to decrease slightly (up to -2.5%), but ΔVF3 (Fig. 9e) maintains a constant level.

That is, in the case of Comparative Example 1 and Comparative Example 3, it can be seen that the reliability is significantly lower than the other cases. In addition, in the case of Example 1, both ΔVF1 and ΔVF3 maintained a constant level, and all ten samples showed similar characteristics, indicating that reliability was the best. In addition, in the case of Example 2, it can be seen that ΔVF1 is slightly decreased, but is within an acceptable range, and ΔVF3 is suitable in terms of reliability because it shows constant characteristics.

10A to 10E show emission distributions of semiconductor devices according to various deformations of electrodes. Specifically, FIGS. 10A to 10E show emission distributions of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1, and Example 2 in order. Here, the red region may mean a light emitting region.

In the case of Comparative Example 1, light emission is easily achieved, but it can be seen that the light emitting area is generally distributed in a region adjacent to the first electrode 150 (refer to FIGS. 1 to 3 ). In the case of Comparative Examples 2 and 3, it can be seen that the light emitting area is evenly distributed compared to Comparative Example 1, but the light emission is slightly insignificant. In the case of Example 1, it can be seen that the light emitting area is evenly distributed, and light emission is easily performed. In the case of Example 2, it can be seen that the light emission is slightly insignificant.

As a result, it can be seen that, in the case of Example 1, light emission is effectively achieved, and in particular, the light emitting area is evenly distributed to increase the current dispersion efficiency.

11A to 11E are photographs of appearances of semiconductor devices according to various deformations of electrodes. 12A to 12E are photographs taken in detail of the exterior features of FIGS. 11A to 11E . 13A to 13E are photographs of cross-sections of electrodes according to various modifications. Specifically, FIGS. 11A to 11E, FIGS. 12A to 12E and FIGS. 13A to 13E show appearances of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1 and Example 2 in that order. Also, FIGS. 11A to 13E may be observations of changes in electrodes after the reliability evaluation according to FIGS. 9A to 9E is performed.

Meanwhile, although not shown, the electrode disposed on the left side of FIGS. 11A to 11E may be the second electrode 160 , and the electrode disposed on the right side may be the first electrode 150 . Also, as described above, each of the first and second electrodes may include pad electrodes 150a and 160a and branch electrodes 150b and 160b. In addition, both the first electrode 150 and the second electrode 160 may have the same structure.

Also, FIGS. 12A and 12B may be observations of the end of the first branch electrode 150b. 12C may be an observation of the second pad electrode 150a. 12D and 12E may be observations of a portion of the first branch electrode 150b. 13A to 13E may be observations of a portion of the second branch electrode.

11A and 11B , in the case of Comparative Examples 1 and 2, it can be seen that, when observed from the top, there is no apparent singularity. However, referring to FIGS. 12A and 12B , when viewed from the side, it can be seen that a fine peeling phenomenon occurred in the first electrodes of Comparative Examples 1 and 2 . That is, in the case of Comparative Examples 1 and 2, it can be seen that the non-contact phenomenon with the semiconductor device is made by the separation of the electrode. As a result, it can be seen that in Comparative Examples 1 and 2, the operating voltage ΔVF3 was increased due to the electrode peeling off.

11C to 11E , in Comparative Example 3 and Examples 1 and 2, a singularity in the appearance of the electrode can be observed. In particular, referring to FIGS. 12C to 12E , it can be seen that the material in the electrode has escaped to the outside of the electrode. However, it can be seen that the operating voltage ΔVF3 of Comparative Examples 3 and 1 and 2 is maintained at a constant level even when such a phenomenon (a phenomenon in which the material in the electrode escapes to the outside) occurs.

On the other hand, referring to FIGS. 13A and 13B , in Comparative Examples 1 and 2, a phenomenon in which the material in the electrode escapes to the outside of the electrode was not observed. However, referring to FIGS. 13C to 13E , it can be seen that in Comparative Examples 3 and 1 and 2, pores are observed in the reflective layer (Al). Accordingly, it can be seen that the material that escapes to the outside of the electrode is Al in the reflective layer.

That is, in the case of the embodiment of the present invention, the first layer 153a and the second layer 153b included in the capping layer 153 may have opposite internal stresses. Accordingly, the internal stresses of the first layer 153a and the second layer 153b cancel each other out, so that deformation of the capping layer 153 and the reflective layer 152 bonded thereto can be minimized. That is, the electrode peeling phenomenon can be prevented.

In this way, in Comparative Examples 1 and 2, it can be seen that the capping layer contains only Ni having a positive internal stress, so that the electrode peeling phenomenon occurs ( FIGS. 12A and 12B ). In addition, in the case of Examples 1 and 2, since the internal stress of the capping layer is canceled and the reflective layer receives a force toward the side, it can be seen that the material of the reflective layer has escaped to the outside of the electrode ( FIGS. 12D and 12E ) .

14A to 14E are observations of whether the electrode peeling phenomenon occurs according to various deformations. 15A to 15E are observations of whether an electrode peeling phenomenon occurs according to various deformations. Specifically, FIGS. 14A to 14E and FIGS. 15A to 15E show appearances of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1, and Example 2 in that order. Also, FIGS. 14A to 15E may be observations of changes in electrodes after the reliability evaluation according to FIGS. 9A to 9E is performed. In addition, FIGS. 14A to 14E may be observations of a peeling phenomenon at the end of the second branch electrode, and FIGS. 15A to 15E may be observations of a peeling phenomenon at the end of the first branch electrode.

14A to 14E , it can be seen that the second electrode has a relatively neat appearance. In addition, it can be seen that the electrode peeling phenomenon does not occur in general. That is, it can be seen that the second electrode has generally excellent reliability even when the semiconductor device is driven under severe conditions.

On the other hand, referring to FIGS. 15A to 15E , in the case of the first electrode, it can be seen that the electrode peeling phenomenon and the material inside the electrode come out occur. Through this, it can be seen that, when the semiconductor device is driven under severe conditions, reliability problems occur more in the first electrode than in the second electrode.

Specifically, in the case of Comparative Example 1, the electrode peeling phenomenon was observed. Therefore, it can be seen that Comparative Example 1 has a result in which the operating voltage is increased as shown in FIG. 9A .

In the case of Comparative Example 2, a peeling phenomenon was not observed in the electrode observed in FIG. 15B. However, a peeling phenomenon occurred in the electrode observed in FIG. 12B . Accordingly, it can be seen that Comparative Example 2 has a result in which the operating voltage is slightly increased as shown in FIG. 9B .

In the case of Comparative Example 3 and Examples 1 and 2, the electrode peeling phenomenon was not observed. Therefore, it can be confirmed that Comparative Example 3 and Examples 1 and 2 have a constant operating voltage as shown in FIGS. 9C to 9E .

As a result, it can be confirmed that Example 1 has the best reliability in terms of operating voltage, light emission distribution, and appearance characteristics.

As such, in the semiconductor device according to the embodiment of the present invention, the capping layer of the first electrode and the second electrode may include a plurality of layers. Specifically, the capping layer may have a structure in which the first layer and the second layer are alternately disposed at least once or more. By alternately stacking the first and second layers, internal stress in the capping layer may be relieved. In this case, the first layer and the second layer may have opposite internal stresses. Alternatively, the internal stress of the first layer may be 0, and the second layer may have a thin thickness such that the internal stress of the capping layer is not made to be deformed.

Accordingly, the stress between the first layer and the second layer is canceled and the electrode peeling phenomenon can be prevented. In particular, the electrode may be prevented from floating even under high current and high temperature conditions, thereby improving the reliability of the semiconductor device.

The semiconductor device may be used as a light source of a lighting system, or may be used as a light source of an image display device or a light source of a lighting device. That is, the semiconductor element may be applied to various electronic devices that are disposed in a case and provide light. For example, when a semiconductor device and RGB phosphor are mixed and used, white light having excellent color rendering properties (CRI) may be realized.

The above-described semiconductor device may be configured as a light emitting device package and may be used as a light source of a lighting system, for example, may be used as a light source of an image display device or a light source of a lighting device.

When used as a backlight unit of an image display device, it can be used as an edge-type backlight unit or as a direct-type backlight unit. may be

The light emitting device includes a laser diode in addition to the above light emitting diode.

The laser diode may include a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer having the above-described structure in the same manner as the light emitting device. And, it uses the electro-lminescence phenomenon in which light is emitted when a current flows after bonding a p-type first conductivity type semiconductor and an n-type second conductivity type semiconductor. There is a difference in the direction and phase of light. That is, the laser diode uses a phenomenon called stimulated emission and constructive interference, so that light having one specific wavelength (monochromatic beam) can be emitted with the same phase and in the same direction. Therefore, it can be used for optical communication, medical equipment, and semiconductor processing equipment.

As the light receiving element, a photodetector, which is a kind of transducer that detects light and converts its intensity into an electrical signal, may be exemplified. As such a photodetector, a photovoltaic cell (silicon, selenium), an optical output device (cadmium sulfide, cadmium selenide), a photodiode (for example, a PD having a peak wavelength in a visible blind spectral region or a true blind spectral region), a photo A transistor, a photomultiplier tube, a phototube (vacuum, gas-filled), an IR (Infra-Red) detector, etc., but the embodiment is not limited thereto.

In addition, a semiconductor device such as a photodetector may be generally manufactured using a direct bandgap semiconductor having excellent light conversion efficiency. Alternatively, the photodetector has various structures, and the most common structures include a pin-type photodetector using a pn junction, a Schottky-type photodetector using a Schottky junction, and a Metal Semiconductor Metal (MSM) photodetector. have.

A photodiode may include a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer having the above-described structure in the same way as the light emitting device, and has a pn junction or pin structure. The photodiode operates by applying a reverse bias or zero bias, and when light is incident on the photodiode, electrons and holes are generated and a current flows. In this case, the magnitude of the current may be substantially proportional to the intensity of light incident on the photodiode.

A photovoltaic cell or solar cell is a type of photodiode, and may convert light into electric current. The solar cell may include a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer having the above-described structure, similarly to the light emitting device.

In addition, it may be used as a rectifier of an electronic circuit through the rectification characteristic of a general diode using a p-n junction, and may be applied to an oscillation circuit by being applied to a very high frequency circuit.

In addition, the above-described semiconductor device is not necessarily implemented only as a semiconductor, and may further include a metal material in some cases. For example, a semiconductor device such as a light receiving device may be implemented using at least one of Ag, Al, Au, In, Ga, N, Zn, Se, P, or As, and may be formed by using a p-type or n-type dopant. It may be implemented using a doped semiconductor material or an intrinsic semiconductor material.

Although the embodiment has been described above, it is only an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are not exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

100; semiconductor element 110; Board
120; semiconductor structure 121; first conductivity type semiconductor layer
122; a second conductivity type semiconductor layer 123; active layer
130; current blocking layer 140; ohmic layer
150; first electrode 150a; first pad electrode
150b; first branch electrode 160; second electrode
160a; a first pad electrode 160b; second branch electrode
151; bonding layer 152; reflective layer
153; capping layers 153a, 153b; 1st floor, 2nd floor
154; bonding layer

Claims (13)

Board;
a semiconductor structure disposed on the substrate and including a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer;
a first electrode disposed on the first conductivity-type semiconductor layer; and
a second electrode disposed on the second conductivity-type semiconductor layer;
At least one of the first electrode and the second electrode may include a bonding layer disposed on the first conductivity type semiconductor layer or the second conductivity type semiconductor layer; a reflective layer disposed on the bonding layer; a capping layer disposed on the reflective layer; and a bonding layer disposed on the capping layer,
In the capping layer, the first layer and the second layer are alternately stacked at least once or more,
The first layer comprises Ti,
The ratio of the thickness of the first layer and the second layer is 20:3 to 4:7,
The first layer and the second layer are in contact with each other,
the first layer and the second layer have internal stresses opposite to each other,
The sum of the internal stresses of the first layer and the second layer is 1.6×10-14 d/cm or less. According to claim 1,
The thickness of the first layer is greater than the thickness of the second layer,
A thickness ratio of the first layer and the second layer is 20:3 to 9:7. According to claim 1,
when the internal stress of the first layer is a compressive stress, the internal stress of the second layer is a tensile stress;
When the internal stress of the first layer is a tensile stress, the internal stress of the second layer is a compressive stress. According to claim 1,
The second layer includes any one selected from Ni and Pt,
When the second layer includes Ni, the thickness of the second layer is 35 nm or less,
An internal stress of the second layer is 3.0×10 ^-14 d/cm or less. According to claim 1,
the first electrode includes a first pad electrode and at least one first branch electrode extending from the first pad electrode;
the second electrode includes a second pad electrode and at least one second branch electrode extending from the second pad electrode;
The first pad electrode and the second pad electrode are respectively disposed on one side and the other side of the semiconductor device,
The first branch electrode extends toward the second pad electrode, and the second branch electrode extends toward the first pad electrode. delete delete delete delete delete delete delete delete

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