KR20140022131A - Preparing method for light emitting device module and nitride based semiconductor device using the same - Google Patents

Abstract

The present invention relates to a preparing method for a light emitting device module and a nitride based semiconductor device using the same. According to the present invention, a growth substrate where a nitride based semiconductor layer is grown is removed by a laser lift off process. A sacrificial layer is removed by a wet etching process. Therefore, surface roughness and planarization can be improved. The property of the nitride based semiconductor device can be improved by reducing contact resistance and preventing leakage current or driving voltage error.

Description

A method of manufacturing a nitride-based semiconductor device and a nitride-based semiconductor device by the same {PREPARING METHOD FOR LIGHT EMITTING DEVICE MODULE AND NITRIDE BASED SEMICONDUCTOR DEVICE USING THE SAME}

The present invention relates to a method for producing a nitride-based semiconductor device and to a nitride-based semiconductor device produced by the method.

Recently, due to the rapid development of information and communication technology in the world, communication technology for high-speed, high-capacity signal transmission is rapidly developing. In particular, as the demand for personal mobile phones, satellite communications, military radars, broadcasting communications, and communication repeaters increases in wireless communication technology, the demand for high-speed and high-power electronic devices required for ultra-high speed information communication systems in the microwave and millimeter wave bands increases. have. In addition, a lot of research is being conducted to reduce the energy loss in the application to power devices used in high power.

In particular, GaN-based nitride semiconductors have a large energy gap, high thermal chemical stability, and excellent physical properties such as high electron saturation rate (~ 3 × 10 ⁷ cm / sec). It is easy to apply and is being actively researched around the world. In particular, electronic devices using GaN-based nitride semiconductors have various advantages such as high breakdown electric field (~ 3 × 10 ⁶ V / cm), maximum current density, stable high temperature operation, high thermal conductivity, and the like. Application to high power devices is possible.

In general, a GaN nitride semiconductor is grown on a sapphire substrate. At this time, a sapphire substrate and a GaN nitride semiconductor have a large difference in lattice constant and thermal expansion coefficient, making it difficult to grow single crystals and present many defects in thin film growth. In addition, since the sapphire substrate is an insulator substrate, it is difficult to discharge static electricity flowing from the outside, and there is a disadvantage in that the frequency of generating light emitting devices having poor performance due to the static electricity increases. This leads to several limitations such as lowering the reliability of the device and the need to add a zener diode in the packaging process. In addition, since the sapphire substrate has a low thermal conductivity, it is difficult to dissipate heat generated while the light emitting device is driven to the outside. Therefore, the sapphire substrate has a problem in that a high current for high output of the light emitting device is restricted. have.

The present invention is to solve the above problems, an object of the present invention, by removing the sacrificial layer by wet etching, it is possible to improve the surface roughness and smoothness of the nitride-based semiconductor device, thereby reducing the contact resistance, Disclosed is a method of manufacturing a nitride-based semiconductor device capable of suppressing an operating voltage failure or leakage current, and a nitride-based semiconductor device manufactured by the manufacturing method.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

A first aspect of the present invention can provide a method of manufacturing a nitride-based semiconductor device comprising:

Forming a buffer layer on the growth substrate; Forming a first Al-doped GaN layer on the buffer layer; Forming on the first Al-doped GaN layer; On the sacrificial layer, a first surface in contact with the sacrificial layer has one of Ga polarity and N polarity, and a second surface opposite to the first surface is the first of the Ga polarity and N polarity. Forming a second Al-doped GaN layer having a different polarity than the surface; Forming an AlGaN layer on the second Al-doped GaN layer; Forming a GaN layer on the AlGaN layer; Removing the growth substrate, the buffer layer and the first Al-doped GaN layer using a laser lift-off (LLO); And removing the sacrificial layer using wet etching.

According to one aspect of the invention, before the step of forming a buffer layer on the growth substrate, forming a group III element material layer consisting of group III element polarity so that the surface polarity of the buffer layer facing on the growth substrate is changed It may be to include more, but is not limited thereto.

According to one aspect of the present invention, the forming of the group 3 element material layer is to form a group 3 element including one selected from the group consisting of Ga, Al, In, and combinations thereof on the growth substrate. May be, but is not limited thereto.

According to one aspect of the invention, the sacrificial layer is ZnO, AlN, SnO ₂ , InN, In ₂ O ₃ , ITO, Si ₃ N ₄ , SiO ₂ , SiC, ZrO ₂ , BeMgO, MgZnO, ITO and combinations thereof It may be to include one selected from the group consisting of, but is not limited thereto.

According to one side of the present invention, the step of removing the sacrificial layer using wet etching, hydrochloric acid (HCl), nitric acid (HNO ₃ ), potassium hydroxide (KOH), sodium hydroxide (NaOH), sulfuric acid (H ₂ SO ₄ ), May be a wet etching using a solution selected from the group consisting of phosphoric acid (H ₃ PO ₄ ), chromium oxide (CrO ₃ ), AZ400K (developer) and combinations thereof, but is not limited thereto. .

According to one aspect of the invention, after the step of removing the sacrificial layer using the wet etching, the GaN layer of the GaN layer, AlGaN layer and the second Al-doped GaN layer on a support substrate on which a bonding layer is formed And bonding the bonding layer to face each other, but is not limited thereto.

According to one aspect of the invention, after the step of bonding the GaN layer and the bonding layer to face, further comprising the step of forming a source electrode, a gate electrode and a drain electrode on the second Al-doped GaN layer May be, but is not limited thereto.

According to one aspect of the invention, prior to the formation of the gate electrode, further comprising the step of removing a portion of the second Al-doped GaN layer in which the gate electrode is to be formed, the removal is a two-dimensional electron gas layer (2 -DEG) may be performed until removed.

A second aspect of the present invention can provide a nitride based semiconductor device formed by the method according to the above.

According to one aspect of the invention, after the step of removing the sacrificial layer using the wet etching, on the support substrate on which the ohmic bonding layer is formed, the GaN of the GaN layer, AlGaN layer and the second Al-doped GaN layer The method may further include bonding the layer and the ohmic bonding layer to face each other, but is not limited thereto.

According to one aspect of the invention, after the step of bonding the GaN layer and the ohmic bonding layer to face, forming a lower ohmic electrode and an upper ohmic electrode on the support substrate and the second Al-doped GaN layer, respectively It may be to include more, but is not limited thereto.

A third aspect of the present invention can provide a nitride based semiconductor device formed by the method according to the above.

According to one side of the present invention, the nitride-based semiconductor device may be of a normally off type.

In the method of manufacturing the nitride semiconductor device according to the embodiment of the present invention and the nitride semiconductor device manufactured by the manufacturing method, the growth substrate on which the nitride semiconductor layer is grown is removed by laser lift-off, and the sacrificial layer is removed. By using the wet etching, the surface roughness and smoothness can be improved, the contact resistance can be reduced, and the operating voltage defect or the leakage current can be suppressed, so that the characteristics of the nitride semiconductor device can be improved. have.

1 is a cross-sectional view illustrating a structure of a nitride based semiconductor device according to an embodiment of the present invention.
2A to 2J are process charts for describing a method of manufacturing a nitride based semiconductor device according to an embodiment of the present invention.
3 is a cross-sectional view illustrating a structure of a nitride based semiconductor device according to another embodiment of the present invention.
4 is a cross-sectional view illustrating a structure of a nitride based semiconductor device according to still another embodiment of the present invention.
5 is a cross-sectional view illustrating a structure of a nitride based semiconductor device according to still another embodiment of the present invention.
6A through 6J are flowcharts illustrating a method of manufacturing a nitride based semiconductor device according to still another embodiment of the present invention.
FIG. 7 is a graph showing PL characteristics of Al-doped GaN grown by increasing Al content to 0, 0.18%, 0.34%, 0.45%, and 0.60% during GaN layer growth according to an embodiment of the present invention.
FIG. 8 is a graph of a Hall measurement when the Al content is doped from 0 to 1% during GaN layer growth to grow an Al doped GaN layer according to an embodiment of the present invention.
9 is a SEM photograph of the N-face GaN surface after laser lift-off in accordance with an embodiment of the present invention.
10 is an optical photo of the GaN layer surface after dry etching according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Also, terminologies used herein are terms used to properly represent preferred embodiments of the present invention, which may vary depending on the user, intent of the operator, or custom in the field to which the present invention belongs. Therefore, the definitions of the terms should be made based on the contents throughout the specification. Like reference symbols in the drawings denote like elements.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between .

Throughout the specification, when a member is located on another member, it includes not only when a member is in contact with another member but also when another member exists between the two members.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

1 is a cross-sectional view illustrating a structure of a nitride based semiconductor device according to an exemplary embodiment of the present invention, and FIGS. 2A to 2J are flowcharts illustrating a method of manufacturing a nitride based semiconductor device according to an exemplary embodiment of the present invention. 1 and 2, a method of manufacturing a nitride based semiconductor device and a nitride based semiconductor device according to an embodiment of the present invention will be described.

The nitride based semiconductor device 100 according to the embodiment of the present invention may include a support substrate 110, a bonding layer 120, a GaN layer 130, an AlGaN layer 140, and a second Al-doped nitride based semiconductor. The layer 150 may include a source electrode 170, a drain electrode 180, and a gate electrode 190.

First, as shown in FIG. 2A, the buffer layer 220 may be formed on the growth substrate 210.

The growth substrate 210 is not limited as long as it can grow a semiconductor layer, for example, an insulating substrate such as sapphire or spinel structure MgAl ₂ O ₄ , GaN, GaAs, SiC, Si, ZnO, ZrB ₂ , GaP, diamond, and combinations thereof may be included, but is not limited thereto. The size, thickness and the like of the substrate are not particularly limited. The surface direction of the substrate is not particularly limited, and a just substrate or a substrate provided with an off angle can be used.

The buffer layer 220 may be formed to mitigate lattice mismatch between the GaN layer 130 to be formed later, for example, a group consisting of a GaN layer, an AlN layer, AlGaN, and combinations thereof grown at low temperature. It may be selected from, but is not limited thereto. The buffer layer 120 is not limited as long as it has a lattice constant for relieving stress due to mismatch between the growth substrate 210 and the GaN layer 130 in addition to GaN, AlN, AlGaN, and combinations thereof.

Subsequently, as illustrated in FIG. 2B, a first Al-doped GaN layer 230 may be formed on the buffer layer 220.

The Al content of the first Al-doped GaN layer 230 may be about 0.1 wt% to about 0.6 wt%, but is not limited thereto.

The growth method of the first Al-doped GaN layer 230 is not particularly limited, and may be a physical vapor deposition method or a chemical vapor deposition method, and may include metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy. Molecular beam epitaxy (MBE), vapor phase epitaxy (VPE), hydride vapor phase epitaxy (HVPE), metal organic vapor phase epitaxy (MOVPE), low pressure It can be grown using low pressure chemical vapor deposition (LPCVD), or atomic layer deposition (ALD) methods.

Subsequently, as shown in FIG. 2C, a sacrificial layer 240 may be formed on the first Al-doped GaN layer 230.

The sacrificial layer 240 may be formed of a material capable of wet etching. For example, ZnO, AlN, SnO ₂ , InN, In ₂ O ₃ , ITO, Si ₃ N ₄ , SiO ₂ , SiC, ZrO ₂ , BeMgO , MgZnO, ITO and combinations thereof may be included, but is not limited thereto.

The sacrificial layer 240 is, for example, sputtering, molecular beam epitaxy (MBE), e-beam evaporation, thermal evaporation, atomic layer epitaxy epitaxy (ALE), pulsed laser deposition (PLD), chemical vapor deposition (CVD), sol-gel, and atomic layer deposition (ALD) methods May be, but is not limited thereto.

Subsequently, as illustrated in FIG. 2D, a second Al-doped GaN layer 150 may be formed on the sacrificial layer 240.

The second Al-doped GaN layer 150 may be formed by the same method as the first Al-doped GaN layer 230.

Specifically, in the second Al-doped GaN layer 150, on the sacrificial layer 240, the first surface 150a in contact with the sacrificial layer 240 has the polarity of either Ga polarity or N polarity. A second Al-doped GaN layer 150 having a polarity different from the first surface 150a of the Ga polarity and the N polarity, opposite the first surface 150a. Referring to the enlarged view of FIG. 2D, the crystal structure of the first surface 150a and the second surface 150b of the second Al-doped GaN layer 150 is a Ga element which is a Group 3 element. And N have a structure in which the elements are periodically arranged. In this case, the first surface 150a of the second Al-doped GaN layer 150 may have N polarity in which N elements are arranged, and the second surface 150b contacting the AlGaN layer 140 may be Ga element. May have an arranged Ga polarity. In addition, although not shown in the drawings, in contrast to the above, the first surface 150a of the second Al-doped GaN layer 150 may have a Ga polarity in which Ga elements are arranged, and contact the AlGaN layer 140. The second surface 150b may have an N polarity in which N elements are arranged.

Subsequently, as shown in FIG. 2E, an AlGaN layer 140 may be formed on the second Al-doped GaN layer 150.

The AlGaN layer 140 may also be formed by the same method as the first Al-doped GaN layer 230 and the second Al-doped GaN layer 150.

When the AlGaN layer 140 is formed on the second Al-doped GaN layer 150, the second Al-doped GaN layer 150 and the AlGaN layer 140 may be formed due to the difference in the bandgap energy of the AlGaN layer 140. A 2-dimensional electron gas (2-DEG) (not shown) is formed on an upper portion (upper portion) of the doped GaN layer 150 to serve as a channel layer through which current can flow.

Subsequently, as shown in FIG. 2F, the GaN layer 130 may be formed on the AlGaN layer 140. The GaN layer 130 may also be formed by the same method as the first Al-doped GaN layer 230, the second Al-doped GaN layer 150, and the AlGaN layer 140.

Next, as shown in FIG. 2G, the growth substrate 210, the buffer layer 220 and the first Al-doped GaN layer 230 may be removed using a laser lift-off (LLO). Can be.

When the laser beam is irradiated to the lower portion of the growth substrate 210, the laser beam passes through the growth substrate 210 to separate and remove the growth substrate 210, the buffer layer 220, and the first Al-doped GaN layer 230. It may be, but is not limited thereto.

Subsequently, as shown in FIG. 2H, the sacrificial layer 240 may be removed using wet etching.

Removal of the sacrificial layer 240 is, for example, hydrochloric acid (HCl), nitric acid (HNO ₃ ), potassium hydroxide (KOH), sodium hydroxide (NaOH), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), Chromium oxide (CrO ₃ ), AZ400K (developer) and a wet etching may be performed using a wet etching solution selected from the group consisting of a combination thereof.

For example, the AlN layer may perform wet etching using AZ400K (developer).

By the lift-off, in a state in which the growth substrate 210, the buffer layer 220 and the first Al-doped GaN layer 230 are removed, the buffer layer 220 is removed by wet etching, and the remaining GaN layer ( 130, the growth structure 160 of the AlGaN layer 140 and the second Al-doped GaN layer 150 may be separated. Removal of the buffer layer 220 by wet etching may improve surface roughness and smoothness of the second Al-doped GaN layer 150.

Subsequently, as shown in FIG. 2I, the GaN layer 130 and the bonding layer 110 may be bonded to each other on the supporting substrate 110 on which the bonding layer 120 is formed.

The bonding layer is not limited as long as it is a material capable of contacting the support substrate 110 and the growth structure 160. For example, eutectic solder, high melting solder, lead-free solder, gold, gold alloy, copper, copper Alloy, titanium, titanium alloys, chromium, chromium alloys, nickel, nickel alloys, aluminum, aluminum alloys, vanadium, vanadium alloys and combinations thereof may be selected from, but is not limited thereto.

Subsequently, as illustrated in FIG. 2J, source electrodes 170 and drain electrodes 180 may be formed on both sides of the second Al-doped GaN layer 150, respectively, and the source electrode 170 and the drain may be formed. The gate electrode 190 may be formed between the electrodes 180. An oxide layer may be further formed before forming the gate electrode.

The source electrode 170, the drain electrode 180, and the gate electrode 190 are each independently eg Ag, Au, Al, Cu, Cr, Ni, Pa, Pt, Rh, Sn, Ta, Ti, W , Mo, and combinations thereof may be selected from, but is not limited thereto. The source electrode 170, the drain electrode 180 and the gate electrode 190 are each independently, for example, sputtering, molecular beam epitaxy, e-beam evaporation, heat Thermal evaporation, atomic layer epitaxy (ALE), pulsed laser deposition (PLD), chemical vapor deposition (CVD), sol-gel, or atomic layer It may be formed by an atomic layer deposition (ALD) method.

According to the structure of the nitride-based semiconductor device according to an embodiment of the present application, the portion removed by the laser lift-off may have a very rough surface, the surface roughness of the other layers (all layers formed on the growth substrate) It may affect, but may be alleviated by the sacrificial layer 240, and the surface roughness and smoothness may be improved by wet etching the sacrificial layer 240, the crystallinity of the second Al-doped GaN layer 150 Can improve. Accordingly, the contact resistance with the source electrode 170, the drain electrode 180, and the gate electrode 190 formed on the second Al-doped GaN layer 150 is reduced, thereby resulting from surface roughness. Insufficient operating voltage or leakage current may be prevented, and electrical characteristics of the nitride-based semiconductor device may be improved.

3 is a cross-sectional view illustrating a structure of a nitride based semiconductor device according to another embodiment of the present invention. Before forming the gate electrode, the gate electrode 190 of the second Al-doped GaN layer 150 is formed. The method may further include removing a portion to be formed, and the removing may be performed until the two-dimensional electron gas layer (2-DEG) is removed. The removal may break the two-dimensional electron gas layer (2-DEG) to exhibit a normally off type characteristic.

4 is a cross-sectional view illustrating a structure of a nitride based semiconductor device according to still another embodiment of the present invention, and before the buffer layer 220 is formed on the growth substrate 210, the surface facing the growth substrate may be formed. In order to change the surface polarity of the buffer layer 220, the group III element material layer 215 having the group III element polarity may be additionally formed. The Group 3 element material layer 215 may be, for example, one selected from the group consisting of Ga, Al, In, and combinations thereof, but is not limited thereto. By further forming the group III element material layer 215, the surface roughness and the surface roughness when performing the laser lift-off for the removal of the growth substrate 210, the buffer layer 220 and the first Al-doped GaN layer 230. Smoothness can be improved. In this case, a 2-dimensional electron gas (2-DEG) (not shown) is formed on the lower portion (lower portion) of the GaN layer 130 to serve as a channel layer through which current can flow.

5 is a cross-sectional view illustrating a structure of a nitride based semiconductor device according to still another embodiment of the present invention, and FIGS. 6A to 6J are flowcharts illustrating a method of manufacturing a nitride based semiconductor device according to another embodiment of the present invention. to be. 5 and 6, a method of manufacturing a nitride based semiconductor device and a nitride based semiconductor device according to still another embodiment of the present invention will be described.

In the nitride-based semiconductor device 300 according to another embodiment of the present invention, the support substrate 310, the bonding layer 320, the GaN layer 330, the AlGaN layer 340, the second Al-doped nitride-based The semiconductor layer 350, the upper ohmic electrode 370, and the lower ohmic electrode 380 may be included.

First, as shown in FIG. 6A, a buffer layer 420 may be formed on the growth substrate 410.

The growth substrate 210 is not limited as long as it can grow a semiconductor layer, for example, an insulating substrate such as sapphire or spinel structure MgAl ₂ O ₄ , GaN, GaAs, SiC, Si, ZnO, ZrB ₂ , GaP, diamond, and combinations thereof may be included, but is not limited thereto. The size, thickness and the like of the substrate are not particularly limited. The surface direction of the substrate is not particularly limited, and a just substrate or a substrate provided with an off angle can be used.

The buffer layer 420 may be formed to mitigate lattice mismatch between the GaN layer 130 to be formed later, for example, a group consisting of a GaN layer, an AlN layer, AlGaN, and combinations thereof grown at low temperature. It may be selected from, but is not limited thereto. The buffer layer 420 is not limited as long as it has a lattice constant for relieving stress due to mismatch between the growth substrate 410 and the GaN layer 470, in addition to GaN, AlN, AlGaN, and combinations thereof.

Subsequently, as illustrated in FIG. 6B, a first Al-doped GaN layer 430 may be formed on the buffer layer 420.

The Al content of the first Al-doped GaN layer 430 may be about 0.1 wt% to about 0.6 wt%, but is not limited thereto.

The growth method of the first Al-doped GaN layer 430 is not particularly limited, and may be a physical vapor deposition method or a chemical vapor deposition method, and may include metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy. Molecular beam epitaxy (MBE), vapor phase epitaxy (VPE), hydride vapor phase epitaxy (HVPE), metal organic vapor phase epitaxy (MOVPE), low pressure It can be grown using low pressure chemical vapor deposition (LPCVD), or atomic layer deposition (ALD) methods.

Subsequently, as illustrated in FIG. 6C, a sacrificial layer 440 may be formed on the first Al-doped GaN layer 430.

The sacrificial layer 440 may be formed of a material capable of wet etching. For example, ZnO, AlN, SnO ₂ , InN, In ₂ O ₃ , ITO, Si ₃ N ₄ , SiO ₂ , SiC, ZrO ₂ , BeMgO , MgZnO, ITO and combinations thereof may be included, but is not limited thereto.

The sacrificial layer 440 may be formed of, for example, sputtering, molecular beam epitaxy (MBE), e-beam evaporation, thermal evaporation, atomic layer epitaxy epitaxy (ALE), pulsed laser deposition (PLD), chemical vapor deposition (CVD), sol-gel, and atomic layer deposition (ALD) methods May be, but is not limited thereto.

Subsequently, as illustrated in FIG. 6D, a second Al-doped GaN layer 450 may be formed on the sacrificial layer 440.

The second Al-doped GaN layer 450 may be formed by the same method as the first Al-doped GaN layer 430.

Specifically, in the second Al-doped GaN layer 450, on the sacrificial layer 440, the first surface 450a in contact with the sacrificial layer 440 has a polarity of either Ga polarity or N polarity. A second Al-doped GaN layer 450 having a polarity different from the first surface 450a of the Ga polarity and the N polarity opposite to the first surface 450a. 6D, the crystal structure of the first surface 450a and the second surface 450b of the second Al-doped GaN layer 450 is a Ga element which is a Group 3 element. And N have a structure in which the elements are periodically arranged. In this case, the first surface 450a of the second Al-doped GaN layer 450 may have N polarity in which N elements are arranged, and the second surface 450b in contact with the AlGaN layer 440 may be Ga element. May have an arranged Ga polarity. In addition, although not shown in the drawing, in contrast to the above, the first surface 450a of the second Al-doped GaN layer 450 may have a Ga polarity in which Ga elements are arranged and contact the AlGaN layer 440. The second surface 450b may have an N polarity in which N elements are arranged.

Subsequently, as shown in FIG. 6E, an AlGaN layer 440 may be formed on the second Al-doped GaN layer 450.

The AlGaN layer 440 may also be formed by the same method as the first Al-doped GaN layer 430 and the second Al-doped GaN layer 450.

Subsequently, as shown in FIG. 6F, a GaN layer 430 may be formed on the AlGaN layer 440.

The GaN layer 430 may also be formed by the same method as the first Al-doped GaN layer 430, the second Al-doped GaN layer 450, and the AlGaN layer 440.

Subsequently, as shown in FIG. 6G, the growth substrate 410, the buffer layer 420, and the first Al-doped GaN layer 430 may be removed using a laser lift-off (LLO). Can be.

When the laser beam is irradiated below the growth substrate 410, the laser beam passes through the growth substrate 410 to separate the growth substrate 410, the buffer layer 420, and the first Al-doped GaN layer 430. The growth substrate 410 may be removed.

Subsequently, as shown in FIG. 6H, the sacrificial layer 440 may be removed using wet etching.

Removal of the sacrificial layer 440 is, for example, hydrochloric acid (HCl), nitric acid (HNO ₃ ), potassium hydroxide (KOH), sodium hydroxide (NaOH), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), Chromium oxide (CrO ₃ ), AZ400K (developer) and a wet etching may be performed using a wet etching solution selected from the group consisting of a combination thereof.

For example, the AlN layer may perform wet etching using AZ400K (developer).

The sacrificial layer 440 is wetted by the wet etching of the sacrificial layer 440 while the growth substrate 410, the buffer layer 420, and the first Al-doped GaN layer 430 are removed by laser lift-off. The remaining growth structure 160 of the GaN layer 330, the AlGaN layer 340, and the second Al-doped GaN layer 350 may be separated. Removal of the buffer layer 420 by wet etching may improve surface roughness and smoothness of the second Al-doped GaN layer 350.

Subsequently, as shown in FIG. 6I, the GaN layer 330 and the ohmic bonding layer 320 may be bonded to each other on the support substrate 310 on which the ohmic bonding layer 320 is formed.

The ohmic bonding layer 320 may include, for example, one selected from the group consisting of Ni / Au, CuInO ₂ / Au, ITO / Au, Ni / Pt / Au, Pt / Au, and combinations thereof. However, the present invention is not limited thereto.

Subsequently, as shown in FIG. 6J, the lower ohmic electrode 370 and the upper ohmic electrode 380 may be formed on the support substrate 310 and the second Al-doped GaN layer 350, respectively.

The lower ohmic electrode 370 and the upper ohmic electrode 380 are each independently Ni, Ti, TiN, Pt, Au, RuO ₂ , V, W, WN, Hf, HfN, Mo, NiSi, CoSi _{2, for example.} , WSi, PtSi, Ir, Zr, Ta, TaN, Cu, Ru, Co, and combinations thereof may be included, but is not limited thereto. And combinations thereof, but is not limited thereto. The lower ohmic electrode 370 and the upper ohmic electrode 380 are each independently, for example, sputtering, molecular beam epitaxy, e-beam evaporation, and thermal evaporation. ), Atomic layer epitaxy (ALE), pulsed laser deposition (PLD), chemical vapor deposition (CVD), sol-gel, or atomic layer deposition It may be formed by a deposition (ALD) method.

In the structure of the nitride-based semiconductor device according to another embodiment of the present application, the portion removed by the laser lift-off may have a very rough surface, the surface roughness of the layer (all layers formed on the growth substrate) It may affect, but may be relaxed by the sacrificial layer 440, and the surface roughness and smoothness may be improved by wet etching the sacrificial layer 240, thereby determining the crystal of the second Al-doped GaN layer 350. Can improve the sex. Accordingly, the contact resistance with the upper ohmic electrode 380 formed on the second Al-doped GaN layer 350 is reduced, thereby preventing an operating voltage defect or leakage current caused by surface roughness. The electrical properties of the nitride-based semiconductor device can be improved.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[ Example ]

After the low-temperature GaN buffer layer, the first Al-doped GaN layer, the ZnO sacrificial layer, the second Al-doped GaN layer, the AlGaN layer, and the GaN layer are sequentially formed on the sapphire substrate, the sapphire substrate is laser lifted off. The GaN layer, the AlGaN layer, and the second Al-doped GaN layer were separated by removing using a technique and removing a ZnO sacrificial layer using KOH. Then, using the bonding layer on the substrate, the GaN layer, the AlGaN layer and the second Al-doped GaN layer are bonded so that the bonding material and the GaN layer face each other, and the source electrode on the second Al-doped GaN layer, A drain electrode and a gate electrode were formed to fabricate a nitride semiconductor device having an N-face GaN power heterojunction field effect transistor (HFET) structure.

In this embodiment, the heat dissipation characteristic of sapphire can be applied to a high power device by improving heat dissipation characteristics by using a laser lift-off technique and a wafer bonding technique. In addition, ZnO can be wet-etched during GaN layer growth to control the operating voltage failure or surface leakage current caused by the Ga drop on the N-face GaN surface and the rough surface caused by the buffer layer after laser lift-off. By inserting the layer as a sacrificial layer, the surface can be protected after laser lift off. In order to form an Al-doped GaN layer as a channel layer in an improved crystallinity, Al may be doped into the GaN layer to reduce defects such as Ga attackers. FIG. 7 is a graph showing PL characteristics of Al-doped GaN grown by increasing the Al content to 0, 0.18%, 0.34%, 0.45%, and 0.60% during GaN layer growth. The Al-doped GaN layer having an Al content of 0.45% has about 10 times improved intensity as compared to the undoped GaN layer. This is because a small amount of Al isoelectronically doped during GaN growth, thereby reducing recombination levels such as nonradiative recombination centers, thereby improving optical properties.

FIG. 8 illustrates Hall measured values when the Al content is doped from 0 to 1% during the GaN layer growth in order to grow the Al doped GaN layer. As doping with Si increased the doping concentration as the Al content increased to 1%. When the Al content is about 0.45%, it can be seen that the mobility of about 600 cm ² / Vs is increased and shows a doping concentration of 3 × 10 ¹⁷ / cm ³ . As such, doping of a small amount of Al in GaN layer reduces defects such as Ga vacancy that traps electrons, thereby improving crystallinity and increasing the number of carriers to increase electrical properties and optical properties. Properties could be improved. However, when the Al content is more than 0.60%, it can be seen that the optical and electrical properties are lowered again.

9 shows an SEM image of the surface of an N-face GaN layer after laser lift-off. As shown in FIG. 9, the roughness of the surface can be seen due to the Ga drop and the remaining LT-buffer GaN layer. When dry etching is performed such as ICP-RIE, there is a problem that the surface roughness is projected to the etched GaN layer surface as shown in the optical photo of FIG. 10. When wet etching with KOH, the GaN layer with N-face has a more rough surface. Such roughness of the surface has a disadvantage of increasing the contact resistance with the metal electrode and causing leakage current to the surface. When the ZnO layer is grown at the position to be etched to improve such a problem, a flat surface may be obtained by etching the ZnO layer through wet etching by using a difference in etching rates of the GaN layer and the ZnO layer.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

100 and 300: nitride semiconductor element
110, 310: support substrate
120: bonding layer
150, 350: second Al-doped nitride based semiconductor layer
160, 360: growth structure
170: source electrode
180: drain electrode
190: gate electrode
210, 410: growth substrate
220, 420: buffer layer
230, 430: first Al-doped GaN layer
240, 440: sacrificial layer
320: ohmic bonding layer
370: lower ohmic electrode
380: upper ohmic electrode

Claims (12)

Forming a buffer layer on the growth substrate;
Forming a first Al-doped GaN layer on the buffer layer;
Forming a sacrificial layer on the first Al-doped GaN layer;
On the sacrificial layer, a first surface in contact with the sacrificial layer has one of Ga polarity and N polarity, and a second surface opposite to the first surface is the first of the Ga polarity and N polarity. Forming a second Al-doped GaN layer having a different polarity than the surface;
Forming an AlGaN layer on the second Al-doped GaN layer;
Forming a GaN layer on the AlGaN layer;
Removing the growth substrate, the buffer layer and the first Al-doped GaN layer using a laser lift-off (LLO); And
Removing the sacrificial layer using wet etching
A method of manufacturing a nitride-based semiconductor device comprising a.
The method of claim 1,
Before forming the buffer layer on the growth substrate, forming a group III element material layer having a group III element polarity such that the surface polarity of the buffer layer facing the growth substrate is changed.
Further comprising, the nitride-based semiconductor device manufacturing method.
3. The method of claim 2,
Forming the Group 3 element material layer,
Forming a group III element including the one selected from the group consisting of Ga, Al, In and combinations thereof on the growth substrate, a method for manufacturing a nitride-based semiconductor device.
The method of claim 1,
The sacrificial layer is selected from the group consisting of ZnO, AlN, SnO ₂ , InN, In ₂ O ₃ , ITO, Si ₃ N ₄ , SiO ₂ , SiC, ZrO ₂ , BeMgO, MgZnO, ITO and combinations thereof A method of manufacturing a nitride-based semiconductor device that comprises.
The method of claim 1,
Removing the sacrificial layer by using wet etching,
Hydrochloric acid (HCl), nitric acid (HNO ₃ ), potassium hydroxide (KOH), sodium hydroxide (NaOH), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), chromium oxide (CrO ₃ ), AZ400K and their Wet etching is performed using a solution selected from the group consisting of combinations, a method for manufacturing a nitride-based semiconductor device.
The method of claim 1,
After removing the sacrificial layer using the wet etching,
Bonding the GaN layer and the bonding layer of the GaN layer, the AlGaN layer, and the second Al-doped GaN layer to face each other on the support substrate on which the bonding layer is formed;
Further comprising, the nitride-based semiconductor device manufacturing method.
The method according to claim 6,
After the step of bonding the GaN layer and the bonding layer facing,
Forming a source electrode, a gate electrode and a drain electrode on the second Al-doped GaN layer
Further comprising, the nitride-based semiconductor device manufacturing method.
The method of claim 7, wherein
Before the formation of the gate electrode,
Removing a portion of the second Al-doped GaN layer in which the gate electrode is to be formed;
Further comprising:
The removal is performed until the two-dimensional electron gas layer (2-DEG) is removed,
A method for producing a nitride semiconductor device.
The method of claim 1,
After removing the sacrificial layer using the wet etching,
Bonding the GaN layer and the ohmic bonding layer of the GaN layer, the AlGaN layer, and the second Al-doped GaN layer to face each other on the support substrate on which the ohmic bonding layer is formed;
Further comprising, the nitride-based semiconductor device manufacturing method.
10. The method of claim 9,
After the step of bonding the GaN layer and the ohmic bonding layer facing,
Forming a lower ohmic electrode and an upper ohmic electrode on the support substrate and the second Al-doped GaN layer, respectively
Further comprising, the nitride-based semiconductor device manufacturing method.
A nitride based semiconductor device formed by the method according to any one of claims 1 to 10.
12. The method of claim 11,
The nitride-based semiconductor device is a normally off type, nitride-based semiconductor device.

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