KR20170113796A - Method for manufacturing gallium-nitride-based photodetector and gallium-nitride-based photodetector manufactured thereby - Google Patents

Abstract

Preparing an epitaxial growth substrate having a buffer layer of a GaN series, an AlGaN layer of a pin or nip structure, a p-type or n-type GaN layer, and a first electrode on a first substrate; Preparing a bonded substrate having a second electrode formed on a second substrate; Bonding the first electrode and the second electrode to each other; Removing the buffer layer after removing the first substrate; And forming an upper electrode on the AlGaN layer of the open or pin or nip structure. A method of manufacturing a gallium nitride-based photodetecting device and a gallium nitride-based photodetecting device manufactured thereby are provided.
According to the present invention, it is possible to manufacture a photodetector with a high efficiency by a simple process introduction and an expensive substrate recycling by a low-cost process, and it can be used for a flexible device and can be stably installed in an extreme environment requiring high heat dissipation characteristics. It is possible to manufacture.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gallium nitride-based photodetector and a gallium nitride-based photodetector,

The present invention relates to a method for producing a gallium nitride-based photodetecting device and a gallium nitride-based photodetecting device produced thereby. More particularly, the present invention relates to a method for producing a gallium nitride-based ultraviolet light detecting element and a gallium nitride-based ultraviolet light detecting element produced thereby.

Generally, a method of manufacturing a gallium nitride (GaN) -based ultraviolet light detecting device (or a photodetector) includes: (i) growing a GaN or AlN template on a substrate and then growing an AlGaN pin structure to form a top- (Ii) a method in which an AlN layer is grown on a double-side polished sapphire substrate, then an AlGaN pin structure is grown thereon and back-illuminated with a sapphire substrate, (iii) a method in which an AlN layer is grown on a silicon wafer There is a method of growing an AlGaN pin structure thereon and then removing the silicon wafer and back-illuminating it.

According to the above-described conventional photodetecting device manufacturing method, it is necessary to use an expensive substrate, to grow at a high temperature, to reduce the light detection efficiency according to the thick buffer layer and the substrate arranged in the incident light direction, to increase defects due to large lattice mismatch, Therefore, it is difficult to fabricate a flexible photodetecting device.

Therefore, there is a need to develop a photodetecting device manufacturing method capable of solving the above-mentioned problems.

One aspect of the present invention is to grow a GaN-based light-detecting multilayer through a substrate having a smaller energy mismatch than a silicon wafer and having a well-established energy band gap, It is possible to reduce the economic burden due to the use of the substrate, minimize the complicated AlN growth process at a high temperature, reduce the process cost by introducing a GaN buffer layer, and use a flexible substrate or an inexpensive heat sink plate as a bonding substrate, A manufacturing method is proposed.

Another aspect of the present invention is to provide a gallium nitride-based photodetector element having a high fill factor due to the adoption of a vertical structure, excellent in light detection efficiency, and applicable to an extreme environment requiring high heat dissipation characteristics or a flexible element I want to present it.

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.

According to an aspect of the present invention, there is provided a GaN buffer layer, comprising: a first substrate; a GaN buffer layer formed on the first substrate; a AlGaN layer having a pin or nip structure formed on the GaN buffer layer; preparing an epitaxially grown substrate having a p-type or n-type GaN layer formed on an n-type AlGaN layer and a first electrode formed on the p-type or n-type GaN layer; Preparing a bonded substrate having a second substrate and a second electrode formed on the second substrate; Bonding the first electrode and the second electrode to each other; Removing the buffer layer after removing the first substrate; And forming an upper electrode on the AlGaN layer of the pin or nip structure opened after the buffer layer is removed.

According to another aspect of the present invention, there is provided a light emitting device comprising a first electrode, a p-type or n-type GaN layer formed on the first electrode, and an AlGaN layer having a pin or nip structure formed on the p- Wherein the bonding substrate has a substrate and a second electrode formed on the substrate, wherein the first electrode and the second electrode are bonded to each other to be connected to each other, and the open pin or nip structure And an upper electrode on the AlGaN layer of the gallium nitride-based light detecting element.

According to the present invention, it is possible to manufacture a photodetector with high efficiency by a simple process introduction and a high cost substrate recycling by a low-cost process, to manufacture a photodetector which is stable in an extreme environment which can be used for a flexible device, Is possible.

FIGS. 1 to 8 illustrate a method of fabricating a nitride-based photodetecting device according to an embodiment of the present invention.
1 is a cross-sectional view of an epitaxial growth substrate after epitaxial layer growth and a first electrode are formed on a first substrate, FIG. 2 is a cross-sectional view of the epitaxial growth substrate after forming a device protective layer 210 and a second electrode on a second substrate, FIG. 3 is a cross-sectional view after the bonding substrate and the epitaxial growth substrate are bonded, FIG. 4 is a view of removing the first substrate by a laser lift-off process, FIG. 5 is a sectional view after the first substrate is removed, 6 is a cross-sectional view after removing the buffer layer. FIG. 7 is a cross-sectional view after forming an upper electrode and after forming an antireflection film without a recess process, and FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a member is "positioned" on another member, it includes not only when a member is in contact with another member but also when another member is present between the two members.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The word " step (or step) "or" step "used to the extent that it is used throughout the specification does not mean" step for.

The use of terms such as " comprising "or" comprising "in this specification should not be construed as necessarily including the various elements or steps described in the specification, including some or all of the steps Or may further include additional components or steps.

Furthermore, terms including ordinals such as first, second, etc. used in this specification can be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The present invention relates to a method of manufacturing a gallium nitride-based photodetecting device.

The GaN-based photodetecting device of the present invention comprises a first substrate, a GaN buffer layer formed on the first substrate, an AlGaN layer formed on the buffer layer of the GaN series, a pin or nip structure, an AlGaN layer of the pin or nip structure A p-type or n-type GaN layer formed on the p-type or n-type GaN layer, and a first electrode formed on the p-type or n-type GaN layer; Preparing a bonded substrate having a first substrate, a second substrate, and a second electrode formed on the second substrate; Bonding the first electrode and the second electrode to each other; Removing the buffer layer after removing the first substrate; And forming an upper electrode on the AlGaN layer of the p-i-n or n-i-p structure opened after the buffer layer is removed.

That is, a method of fabricating a gallium nitride-based photodetector having a high light-receiving efficiency and a high fill factor by manufacturing an ultraviolet photodetector on various substrates including a flexible substrate or a high radiator plate using a substrate removal method do.

1, a GaN-based buffer layer 110 formed on the first substrate 100, a pin or nip formed on the GaN-based buffer layer 110, Type or n-type GaN layer 40 formed on the AlGaN layer 10, 20, 30 of the pin or nip structure, and the p-type or n-type GaN layer 10, And a first electrode (M1) formed on the substrate (40). The AlGaN layers 10, 20 and 30 of the pin or nip structure and the p-type or n-type GaN layer 40 may constitute a photodetector PDL1.

The first substrate 100 may be somewhat expensive, and the lattice mismatching may be smaller than that of the silicon wafer. Since the first substrate 100 is to be separated / removed by a laser lift-off process in a later-described step, the energy band gap of the first substrate is lower than the energy band gap of laser light generated in the laser lift- . The substrate that satisfies such an energy bandgap may be any one selected from the group consisting of sapphire, AlN, diamond, BN, SiC, and GaN, but is not limited thereto.

A GaN-based buffer layer 110 is grown on the first substrate 100.

Conventionally, a GaN-based multilayer is grown by growing an AlN layer. However, in this process, the growth temperature is as high as 1300 DEG C and the internal stress is high, which makes growth difficult. However, the growth thickness of the AlN layer is minimized And a GaN-based buffer layer 110 in which growth conditions are well established even at a low temperature are grown and used. A sacrificial layer may be included between the GaN buffer layer 110 and the first substrate 100 to facilitate separation of the first substrate 100 during the laser lift-off process. Particularly, since GaN-based sacrificial layer (In _x Ga ₁ -xN) containing indium (In) is used when GaN and SiC substrate are used as the first substrate 100, it has a band gap smaller than that of the first substrate 100 A sacrificial layer can be formed.

And the buffer layer 110, the Al composition to have an energy band gap corresponding to the ultraviolet wavelength region to be detected, after growing crystal Al _x Ga _{1 - x} N layer are sequentially laminated. As a result, the AlGaN layers 10, 20, and 30 having a pin or nip structure are grown. X may be 0 < x < = 1, and preferably 0 &lt; x &lt; = 0.7. A p-type or n-type GaN layer 40 is formed on the AlGaN layer 10, 20, 30 having the pin or nip structure.

That is, a structure in which a p-AlGaN layer, an i-AlGaN layer, and an n-AlGaN layer are sequentially stacked on the buffer layer 110 and an n-GaN layer is formed thereon is possible. Also, a structure in which an n-AlGaN layer, an i-AlGaN layer, and a p-AlGaN layer are sequentially stacked on the buffer layer 110 and a p-GaN layer is formed is also possible.

At this time, the x value of the Al _x Ga _{1 - x} N layer is sequentially lowered from the buffer layer 110 toward the GaN layer. The higher the Al composition, the greater the energy bandgap. Therefore, even if light is not absorbed in the Al _x Ga _1-x N layer 10 having a high Al composition, for example, light can be absorbed in the Al _x Ga _{1 - x} N layer 20 having a lower Al composition .

An epitaxial growth substrate is prepared by forming a first electrode (M1) on the p-type or n-type GaN layer (40) to allow ohmic contact. The electrode forming the ohmic contact is preferably a material including any one of titanium, aluminum, vanadium, tantalum, molybdenum, palladium, silicon, nickel, gold, tungsten or at least one of them. Doped silicon or the like may be used.

Thereafter, a mesa etching process may be optionally included for individual device isolation as needed.

On the other hand, a bonded substrate to be bonded to the epitaxial growth substrate is prepared.

As shown in FIG. 2, the bonded substrate stack may include a second substrate 200 and a second electrode M2 formed on the second substrate 200.

The second substrate 200 may be a flexible polymer substrate. Conventionally, when a rigid substrate is used, it is difficult to fabricate a flexible device. However, by using a polymer substrate, a flexible photodetector can be fabricated.

Specifically, the polymer substrate may be formed of at least one selected from the group consisting of polycarbonate (PC), polyethylene naphthalate (PEN), polynorbornene, polyacrylate, polyvinyl alcohol, polyimide polyimide, polyimide, polyethylene terephthalate (PET), polyethersulfone (PES), polystyrene (PS), polypropylene (PP), polyethylene (PE), polyvinylchloride , Polyvinylidene fluoride (PVP), polyamide (PA), polybutylene tererephthalate (PBT), polymethyl methacrylate (PMMA), and polydimethylsiloxane But is not limited thereto.

Also, the second substrate 200 may be a radiator plate. For example, Si, Ge, Al, W, Cr, Ni, Cu or an alloy thereof; Amorphous AlN; Amorphous SiC; graphite; And may be made of nano-carbon. The thermal conductivity of the radiator plate may be greater than the thermal conductivity of the sapphire substrate.

The second substrate 200 may have an adhesive layer for bonding.

In addition, the second substrate 200 may include a device protection layer 210 for protecting the device, and the device protection layer 210 may be selected from the group consisting of SiO ₂ , SiN _x, and Si ₃ N ₄ But it is not limited thereto.

A second electrode M2 for device operation is formed on the second substrate 200 to prepare a bonded substrate.

After the epitaxially grown substrate and the bonded substrate are prepared as described above, the first electrode (M1) of the epitaxial growth substrate and the second electrode (M2) of the bonded substrate are bonded (bonded) to each other as shown in FIG. 3 .

Then, as shown in Fig. 4, the first substrate 100 is removed by a laser lift-off process. The removed first substrate 100 may be recovered and recycled to reduce the manufacturing cost of the photodetector.

Next, as shown in Figs. 5 and 6, the uppermost buffer layer 110 is removed.

The buffer layer 110 is _{BCl 3, SiCl 4, Cl 2} , HBr, SF 6, CF 4, C 4 F 8, CH 4, CHF 3, NF 3, CFCs (chlorofluorocarbons), the group consisting of H ₂ and O ₂ But the present invention is not limited thereto. The dry etching may further include at least one inert gas selected from the group consisting of N2, Ar, and He.

Alternatively, the buffer layer 110 may include at least one of HF, HCl, HNO ₃ , H ₂ SO ₄ , H ₃ PO ₄ , oxalic acid, (BOE), sodium hydroxide (NaOH), potassium hydroxide (KOH), hydrogen peroxide (H ₂ O ₂ ), acetone, TMAH (Tetramethyl armmonium hydroxide), N, N-dimethylacetamide, Or a mixture thereof, by wet etching at a temperature ranging from room temperature to 350 ° C, but is not limited thereto.

After the buffer layer 110 is removed, an upper electrode M3 is formed on the AlGaN layer having the pin or nip structure opened (FIGS. 7 and 8). At this time, the upper electrode M3 may be ohmic contacted. The electrode forming the ohmic contact is preferably a material including any one of titanium, aluminum, vanadium, tantalum, molybdenum, palladium, silicon, nickel, gold, tungsten or at least one of them. Doped silicon or the like may be used.

As shown in FIG. 8, after the step of forming the upper electrode M3, a step of selectively etching a part of the AlGaN layer of the open pin or nip structure to form a recessed region may be added have. By forming the recessed region, the transmission thickness of the incident light can be minimized.

After forming the upper electrode M3, a step of selectively forming a single-layered or multi-layered anti-reflection film 300 on the AlGaN layer 10 having the open pin or nip structure may be added. The anti-reflection film 300 may be formed of a metal oxide, a fluoride, a nitride, or a sulfide, but is not limited thereto. When the antireflection film has a multilayer structure, the refractive index of the lower antireflection film material may be greater than or equal to the refractive index of the antireflection film material of the upper layer.

Another aspect of the present invention is to provide a p-type or n-type GaN layer 40 formed on the p-type or n-type GaN layer 40, a p-type or n-type GaN layer 40 formed on the first electrode M1, (PDL1) having an AlGaN layer (10, 20, 30) of nip structure and a bonding substrate are bonded to each other. The bonding substrate has a substrate and a second electrode (M2) formed on the substrate And an upper electrode M3 on the AlGaN layer 10 having the pin or nip structure opened so that the first electrode M1 and the second electrode M2 are connected to each other. A light detection element is provided.

The gallium nitride-based photodetecting device is manufactured by the above-described method of manufacturing a gallium nitride-based photodetecting device, and details of materials, compositions, and the like of each layer constituting the device are as described above, .

The photodetecting device manufactured through the substrate removing process of the present invention adopts a vertical structure and has a high fill factor. The incident light to be detected is directly incident on the detection layer, and the detection efficiency is high. Accordingly, it is possible to utilize the bonded substrate having high heat dissipation characteristics in an environment requiring high heat dissipation characteristics, and it is possible to increase the light detection efficiency by removing the thick buffer layer and the substrate in the incident light direction.

Claims (24)

A GaN-based buffer layer formed on the first substrate; a AlGaN layer having a pin or nip structure formed on the GaN-based buffer layer; a p-type or n-type GaN layer formed on the AlGaN layer having the pin or nip structure; And a first electrode formed on the p-type or n-type GaN layer;
Preparing a bonded substrate having a first substrate, a second substrate, and a second electrode formed on the second substrate;
Bonding the first electrode and the second electrode to each other;
Removing the buffer layer after removing the first substrate; And
And forming an upper electrode on the AlGaN layer having the pin or nip structure opened after the buffer layer is removed. The method according to claim 1,
Wherein the energy band gap of the first substrate is larger than the energy band gap of laser light generated in the laser lift-off equipment. The method according to claim 1,
Wherein an energy band gap of the buffer layer is smaller than an energy band gap of the first substrate. The method according to claim 1,
Wherein the first substrate is made of any one selected from the group consisting of sapphire, AlN, diamond, BN, SiC and GaN. The method according to claim 1,
Wherein the second substrate is a polymer substrate or a radiator plate whose thermal conductivity is higher than that of the sapphire substrate. 6. The method of claim 5,
The radiator plate may be made of Si, Ge, Al, W, Cr, Ni, Cu or an alloy thereof; Amorphous AlN; Amorphous SiC; graphite; Or a nano-carbon. The method according to claim 1,
Wherein the second substrate comprises an adhesive bonding layer or a device protective layer for bonding. The method according to claim 1,
Wherein the first substrate is removed by a laser lift-off process. The method according to claim 1,
Wherein the buffer layer is removed by dry etching or wet etching. The method according to claim 1,
Further comprising the step of forming a recessed region by etching a part of the AlGaN layer of the open pin or nip structure after the step of forming the upper electrode. The method according to claim 1,
Further comprising the step of forming a single-layered or multi-layered antireflection film on the AlGaN layer having the pin or nip structure. A p-type or n-type GaN layer formed on the first electrode, and an AlGaN layer having a pin or nip structure formed on the p-type or n-type GaN layer,
A bonding substrate comprising a substrate and a second electrode formed on the substrate,
The first electrode and the second electrode are connected to each other to be connected to each other,
And an upper electrode on the AlGaN layer of the pin or nip structure opened. 13. The method of claim 12,
Wherein the AlGaN layer having the pin or nip structure has a structure in which an Al _x Ga _{1 - x} N layer is sequentially laminated, and x is 0 < x &lt; / = 1. 13. The method of claim 12,
Wherein the x value of the Al _x Ga _{1 - x} N layer is sequentially lowered from the upper electrode toward the p-type or n-type GaN layer. 14. The method of claim 13,
Wherein the AlGaN layer having the pin or nip structure has an energy bandgap corresponding to an ultraviolet region. 13. The method of claim 12,
Wherein the substrate is a polymer substrate or a radiator plate whose thermal conductivity is higher than that of a sapphire substrate. 17. The method of claim 16,
The polymer substrate may be formed of a polymer such as polycarbonate (PC), polyethylene naphthalate (PEN), polynorbornene, polyacrylate, polyvinyl alcohol, polyimide, (PET), polyethersulfone (PES), polystyrene (PS), polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC) , Polyamide (PA), polybutylene tererephthalate (PBT), polymethyl methacrylate (PMMA), and polydimethylsiloxane (PDMS). Is a substrate on which a gallium nitride layer is formed. 17. The method of claim 16,
The radiator plate may be made of Si, Ge, Al, W, Cr, Ni, Cu or an alloy thereof; Amorphous AlN; Amorphous SiC; graphite; Wherein the light emitting layer is made of nano-carbon. 17. The method of claim 16,
And a device protection layer is further provided in a part of a region between the photodetector and the bonded substrate. 20. The method of claim 19,
Wherein the device protection layer is made of any one selected from the group consisting of SiO ₂ , SiN _x, and Si ₃ N ₄ . 13. The method of claim 12,
And a part of the AlGaN layer of the pin or nip structure is etched to form a recessed region. 13. The method of claim 12,
Further comprising a single-layered or multi-layered antireflection film on the AlGaN layer having the pin or nip structure. 23. The method of claim 22,
Wherein the antireflection film is made of a metal oxide, a fluoride, a nitride, or a sulfide. 23. The method of claim 22,
Wherein the refractive index of the lower anti-reflective coating material is greater than or equal to the refractive index of the upper anti-reflective coating material when the anti-reflective coating has multiple layers.

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