阅读说明：本技术 一种超薄结构深紫外led及其制备方法 (Ultra-thin structure deep ultraviolet LED and preparation method thereof ) 是由 王永进 于 2019-08-28 设计创作，主要内容包括：本发明公开了一种超薄结构深紫外LED及其制备方法,超薄结构深紫外LED由从上往下依次设置的掺杂n型AlGaN层、量子阱层、p型电子阻挡层和p型GaN层制成的总厚度小于600nm的深紫外LED。超薄结构深紫外LED制备方法：首先光刻定义器件,并通过刻蚀暴露出掺杂n型AlGaN层,其次生长SiO<Sub>2</Sub>钝化层,沉积电极,形成LED结构,通过倒装键合将LED器件和新衬底键合在一起,接着通过激光剥离或研磨抛光工艺去除蓝宝石衬底,进一步减薄去除AlN缓冲层和非掺杂AlGaN层,并减薄掺杂n型AlGaN层,剩余减薄的掺杂n型AlGaN层、量子阱层、p型电子阻挡层和p型GaN层的总厚度小于600nm,形成超薄结构深紫外LED。该超薄结构深紫外LED能抑制器件内波导模式,提升器件的电光转换效率,提高器件的响应速度,根据应用需求不同,可作为发光器件、探测器件等用于率照明、显示和光通信领域。(The invention discloses an ultra-thin structure deep ultraviolet LED and a preparation method thereof, wherein the ultra-thin structure deep ultraviolet LED is a deep ultraviolet LED with the total thickness of less than 600nm, and is prepared by sequentially arranging an n-type AlGaN layer, a quantum well layer, a p-type electron barrier layer and a p-type GaN layer from top to bottom. The preparation method of the ultra-thin structure deep ultraviolet LED comprises the following steps: firstly, defining a device by photoetching, exposing a doped n-type AlGaN layer by etching, and secondly, growing SiO 2 The LED structure is formed by bonding an LED device and a new substrate together through flip-chip bonding, then the sapphire substrate is removed through a laser stripping or grinding polishing process, the AlN buffer layer and the undoped AlGaN layer are further thinned and removed, the doped n-type AlGaN layer is thinned, the total thickness of the residual thinned doped n-type AlGaN layer, the quantum well layer, the p-type electronic barrier layer and the p-type GaN layer is smaller than 600nm, and the ultra-thin structure deep ultraviolet LED is formed. The ultra-thin deep ultraviolet LED can inhibit the waveguide mode in the device and improve the electro-optic conversion of the deviceThe efficiency is improved, the response speed of the device is improved, and the device can be used as a light-emitting device, a detection device and the like in the fields of rate illumination, display and optical communication according to different application requirements.)

1. The utility model provides an ultra-thin structure deep ultraviolet LED which characterized in that: the deep ultraviolet LED with the total thickness less than 600nm is made of a doped n-type AlGaN layer (4), a quantum well layer (5), a p-type electron barrier layer (6), a p-type GaN layer (7) and a new substrate (8) which are arranged from top to bottom in sequence.

2. The ultra-thin structured deep ultraviolet LED of claim 1, wherein: the new substrate (8) is a silicon substrate or a silicon carbide substrate or a nickel-tin substrate.

3. The ultra-thin structured deep ultraviolet LED according to claim 1 or 2, characterized in that: the number of n doped with the n-type AlGaN layer (4) is 1-3.

4. A preparation method of an ultrathin structure deep ultraviolet LED is characterized by comprising the following steps: the method comprises the following steps of selecting a sapphire substrate (1), an AlN buffer layer (2), a non-doped u-type AlGaN layer (3), a doped n-type AlGaN layer (4), a quantum well layer (5), a p-type electronic barrier layer (6) and a p-type GaN layer (7) of which the original wafer structure is from bottom to top, and manufacturing the ultra-thin structure deep ultraviolet LED according to the following steps:

etching an original wafer by using a photoetching definition device, etching from a p-type GaN layer to a sapphire substrate direction, and finally etching the original wafer to expose a part of a doped n-type AlGaN layer;

growing SiO on two sides of the top of the exposed doped n-type AlGaN layer and two sides of the top of the un-etched original wafer far away from the sapphire substrate₂A passivation layer;

step b, preparing the semi-finished product SiO₂Depositing electrodes between the passivation layers and forming an LED structure wafer;

bonding the LED structure wafer obtained in the step c and a new substrate (8) together through flip-chip bonding to obtain a double-substrate LED wafer;

removing the sapphire substrate of the original wafer in the double-substrate LED wafer obtained in the step d through a laser stripping or grinding polishing process, and reserving a new bonded substrate;

and further removing the AlN buffer layer (2) and the undoped u-type AlGaN layer (3), thinning the doped n-type AlGaN layer, and forming the ultra-thin structure deep ultraviolet LED by using the LED structure with the total thickness of the residual doped n-type AlGaN layer (4), the p-type electron blocking layer (6) and the p-type GaN layer (7) being less than 600 nm.

5. The method for preparing the ultra-thin structure deep ultraviolet LED according to claim 4, wherein the method comprises the following steps: the number of n doped with the n-type AlGaN layer (4) is 1-3.

6. The method for preparing the ultra-thin structure deep ultraviolet LED according to claim 4, wherein the method comprises the following steps: and a, etching the doped n-type AlGaN layer to be exposed when the original wafer is etched in the step a.

7. The method for preparing the ultra-thin structure deep ultraviolet LED according to any one of claims 4 to 6, wherein the method comprises the following steps: and d, when the LED obtained in the step c is in flip-chip bonding with the new substrate, bonding the electro-deposition area of the LED crystal wafer obtained in the step c with the new substrate through the metal bonding layer.

8. The method for preparing the ultra-thin structure deep ultraviolet LED according to claim 7, wherein the method comprises the following steps: the new substrate (8) is a silicon substrate or a silicon carbide substrate or a nickel-tin substrate.

Technical Field

The invention relates to the technical field of ultrathin structure deep ultraviolet LEDs and preparation thereof, in particular to an ultrathin structure deep ultraviolet LED and a preparation method thereof.

Background

Ultraviolet LEDs based on AlGaN (aluminum gallium nitride) materials are the main trends of the current nitride technology development and the third generation material technology development, and have wide application prospects. Ultraviolet LEDs are used in a wide range of applications, such as air and water purification, disinfection, ultraviolet medicine, high density optical storage systems, full color displays, and solid state white light illumination. Semiconductor ultraviolet light sources have attracted extensive attention in the semiconductor photovoltaic industry as a further major industry behind semiconductor lighting.

However, unlike blue LEDs, currently, ultraviolet LEDs are in the development stage of technology, and some problems that are difficult to break through exist, such as that AlGaN-based ultraviolet LEDs have relatively low internal quantum efficiency and emission power, and complex structures.

Therefore, how to improve the internal quantum efficiency and the emission power of the AlGaN-based ultraviolet LED becomes a problem to be solved urgently.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the ultra-thin structure deep ultraviolet LED which can inhibit a waveguide mode in a device, improve the electro-optic conversion efficiency of the device, improve the response speed of the device, and can be used as a light-emitting device, a detection device and the like in the fields of rate illumination, display and optical communication according to different application requirements, and the preparation method thereof.

The technical scheme adopted by the invention is as follows: the deep ultraviolet LED with the ultrathin structure is a deep ultraviolet LED with the total thickness of less than 600nm, which is prepared by sequentially arranging an n-type AlGaN doped layer, a quantum well layer, a p-type electron barrier layer, a p-type GaN layer and a new substrate from top to bottom.

A preparation method of an ultra-thin structure deep ultraviolet LED comprises the steps of selecting a sapphire substrate 1, an AlN buffer layer 2, a non-doped u-type AlGaN layer 3, a doped n-type AlGaN layer 4, a quantum well layer 5, a p-type electronic barrier layer 6 and a p-type GaN layer 7 from bottom to top of an original wafer, and manufacturing the ultra-thin structure deep ultraviolet LED according to the following steps:

a. etching an original wafer by using a photoetching definition device, etching from a p-type GaN layer to a sapphire substrate direction, and finally etching the original wafer to expose a part of a doped n-type AlGaN layer;

b. growing SiO2 passivation layers on two sides of the top of the exposed doped n-type AlGaN layer and two sides of the top of the un-etched original wafer far away from the sapphire substrate;

c. depositing electrodes among the SiO2 passivation layers of the semi-finished product prepared in the step b, and forming an LED structure wafer;

d. bonding the LED structure wafer obtained in the step c and the new substrate together through flip-chip bonding to obtain a double-substrate LED wafer;

e. removing the sapphire substrate of the original wafer in the double-substrate LED wafer obtained in the step d through a laser stripping or grinding polishing process, and reserving a new bonded substrate;

f. and further removing the AlN buffer layer 2 and the undoped u-type AlGaN layer 3, thinning the doped n-type AlGaN layer, and forming the ultrathin deep ultraviolet LED by using the LED structure with the total thickness of the residual doped n-type AlGaN layer 4, the p-type electron blocking layer 6 and the p-type GaN layer 7 being less than 600 nm.

Further, the number of n doped n-type AlGaN layer 4 is 1 to 3 layers.

Further, when the original wafer is etched in the step a, the length of the doped n-type AlGaN layer to be exposed is one third to one half of the diameter of the original wafer, so as to deposit an n electrode.

Further, when the LED crystal wafer obtained in step c is flip-chip bonded to a new substrate in step d, the electrodeposition region of the LED crystal wafer obtained in step c is bonded to the new substrate through a metal bonding layer, where the new substrate is a silicon substrate or a silicon carbide substrate, and is usually a silicon substrate.

Compared with the prior art, the invention has the beneficial effects that: the ultra-thin structure deep ultraviolet LED is a deep ultraviolet LED with the total thickness of less than 600nm, and is formed by a doped n-type AlGaN layer, a p-type electron blocking layer, a p-type GaN layer and a sapphire substrate which are sequentially arranged from top to bottom. Therefore, more exciting light of the ultra-thin structure deep ultraviolet LED escapes from the device, and the electro-optic conversion efficiency of the ultra-thin structure deep ultraviolet LED is improved. Meanwhile, after the thickness of the ultra-thin structure deep ultraviolet LED is reduced, the resistance of the ultra-thin structure deep ultraviolet LED is correspondingly reduced, and the resistance-capacitance (RC) constant is reduced, so that the response speed of the device is improved. Moreover, after the thickness of the ultra-thin structure deep ultraviolet LED is reduced, the resistance of the ultra-thin structure deep ultraviolet LED is correspondingly reduced, the generated heat effect is also reduced, and the performance of the ultra-thin structure deep ultraviolet LED is further improved.

The invention discloses a preparation method of an ultrathin structure deep ultraviolet LED, which comprises the following steps: firstly, defining a device by photoetching, exposing a doped n-type AlGaN layer by etching, and secondly, growing SiO₂And a passivation layer and a deposited electrode form an LED structure, the LED device and the new substrate are bonded together through flip-chip bonding, then the sapphire substrate is removed through a laser stripping or grinding and polishing process, the AlN buffer layer and the undoped u-type AlGaN layer are further thinned and removed, the doped n-type AlGaN layer is thinned, the total thickness of the residual doped n-type AlGaN layer, the p-type electron blocking layer and the p-type GaN layer is less than 600nm, and the ultra-thin structure deep ultraviolet LED is formed.

In conclusion, the ultra-thin deep ultraviolet LED can inhibit a waveguide mode in a device, the resistance is correspondingly reduced, the generated heat effect is also reduced, the electro-optic conversion efficiency of the device is improved, the response speed of the device is improved, and the ultra-thin deep ultraviolet LED can be used as a light emitting device, a detection device and the like in the fields of rate illumination, display and optical communication according to different application requirements.

Drawings

FIG. 1 is a diagram of a ultra-thin deep ultraviolet LED structure;

FIG. 2 is a flow chart of ultra-thin deep ultraviolet LED fabrication;

FIG. 3 is a diagram of a raw wafer;

FIG. 4 is a schematic structural diagram of a sub-wavelength ideal vertical structure LED device;

wherein: the solar cell comprises a 1-sapphire substrate, a 2-AlN buffer layer, a 3-undoped u-type AlGaN layer, a 4-doped n-type AlGaN layer, a 5-quantum well layer, a 6-p-type electron barrier layer, a 7-p-type GaN layer and an 8-new substrate.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As shown in figure 1, the ultra-thin structure deep ultraviolet LED is a deep ultraviolet LED with the total thickness of less than 600nm, and is formed by sequentially arranging an n-type AlGaN layer 4, a quantum well layer 5, a p-type electron barrier layer 6, a p-type GaN layer 7 and a new substrate 8 from top to bottom. The new substrate 8 is a silicon substrate, a silicon carbide substrate, or a Ni/Sn substrate (nickel-tin substrate), and is referred to as a common new substrate, but not specifically as a new substrate 8. The preferred embodiment is that the number of n doped n-type AlGaN layer 4 is 1-3, which can ensure its better performance.

As shown in detail in fig. 2, in the method for manufacturing the ultra-thin structure deep ultraviolet LED, a sapphire substrate 1, an AlN buffer layer 2, a non-doped u-type AlGaN layer 3, a doped n-type AlGaN layer 4, a quantum well layer 5, a p-type electron blocking layer 6 and a p-type GaN layer 7 are selected from an original wafer from bottom to top, the structure of the original wafer is shown in fig. 3, and the ultra-thin structure deep ultraviolet LED is manufactured according to the following steps:

a. etching an original wafer by using a photoetching definition device, etching from a p-type GaN layer to a sapphire substrate direction, and finally etching the original wafer to expose a part of a doped n-type AlGaN layer;

b. growing SiO2 passivation layers on two sides of the top of the exposed doped n-type AlGaN layer and two sides of the top of the un-etched original wafer far away from the sapphire substrate;

c. depositing electrodes such as electrodes in fig. 2 between the SiO2 passivation layers of the semi-finished product prepared in the step b, and forming an LED structure wafer;

d. bonding the LED structure wafer obtained in the step c and the new substrate together through flip-chip bonding to obtain a double-substrate LED wafer;

e. removing the sapphire substrate of the original wafer in the double-substrate LED wafer obtained in the step d through a laser stripping or grinding polishing process, and reserving a new bonded substrate;

f. and further removing the AlN buffer layer 2 and the undoped u-type AlGaN layer 3, thinning the doped n-type AlGaN layer, and forming the ultrathin deep ultraviolet LED by using the LED structure with the total thickness of the residual doped n-type AlGaN layer 4, the p-type electron blocking layer 6 and the p-type GaN layer 7 being less than 600 nm.

Comprehensively, the ultra-thin structure deep ultraviolet LED selects an original wafer to comprise a sapphire substrate, an AlN buffer layer, a non-doped u-type AlGaN layer, a doped n-type AlGaN layer, a quantum well layer, a p-type electronic barrier layer and a p-type GaN layer from bottom to top. Firstly, defining a device by photoetching, exposing a doped n-type AlGaN layer by etching, and secondly, growing SiO₂The LED structure is formed by depositing electrodes on a passivation layer, bonding an LED device and a new substrate together through flip-chip bonding, then removing the sapphire substrate through a laser stripping or grinding and polishing process, further thinning and removing an AlN buffer layer and a non-doped u-type AlGaN layer, thinning and doping an n-type AlGaN layer, and forming the ultra-thin structure deep ultraviolet LED, wherein the total thickness of the residual doped n-type AlGaN layer, a quantum well layer, a p-type electronic barrier layer and a p-type GaN layer is less than 600 nm. The ultra-thin deep ultraviolet LED can inhibit a waveguide mode in a device, improves the electro-optic conversion efficiency of the device, improves the response speed of the device, and can be used in the fields of rate illumination, display and optical communication as a light emitting device, a detection device and the like according to different application requirements.

In the above embodiment, the number of n doped with the n-type AlGaN layer 4 is 1 to 3, which has better usability.

In the above embodiment, when the original wafer etching is performed in step a, the length of the doped n-type AlGaN layer to be exposed is etched to be one third to one half of the diameter of the original wafer, so as to better deposit the n electrode between the SiO2 passivation layer of the semi-finished product obtained in step b, and provide sufficient electron deposition space for the n electrode.

In the above embodiment, when the LED crystal wafer obtained in step c is flip-chip bonded to a new substrate in step d, the electrodeposited region of the LED crystal wafer obtained in step c is bonded to the new substrate through a metal bonding layer (metal in fig. 2), where the new substrate is a silicon substrate or a silicon carbide substrate, and is usually a silicon substrate. The electrode (electrode deposition) adopted by us at present is Ni/Au, and the substrate metal is Ni/Sn, and is used for realizing metal bonding between wafers.

That is to say, in the ultra-thin structure deep ultraviolet LED manufactured by the above method, the total thickness of the selected AlN buffer layer, the undoped u-type AlGaN layer, the doped n-type AlGaN layer, the quantum well layer, the p-type electron blocking layer, and the p-type GaN layer in the original wafer is about 5 micrometers, which is far greater than the light emission wavelength of the ultra-thin deep ultraviolet LED, after the technical route, the thickness of the ultra-thin deep ultraviolet LED only includes the thinned doped n-type AlGaN layer, the quantum well layer, the p-type electron blocking layer, and the p-type GaN layer, and the thickness of the ultra-thin deep ultraviolet LED is less than 600 nm.

The ultra-thin structure deep ultraviolet LED prepared by the method is similar to the sub-wavelength ideal vertical structure LED, and the sub-wavelength ideal vertical structure LED is shown in figure 4, whereind ₀ For the original thickness of the epitaxial layers of the LED device,d ₁ the thickness of the LED with a vertical structure is shown, lambda is the light-emitting central wavelength of the LED device,V _turn-onthe voltage at which the device is turned on,Vthe device is pre-charged.

As seen from FIG. 4, the sub-wavelength ideal vertical structure LED has a silver layer Ag, a metal Bonding layer Bonding metal, a Silicon layer Silicon, and a Cr/Pt/Au layer as an electron deposition layer sequentially bonded to the bottom of p-GaN of a bonded wafer including p-GaN, MQW, n-GaN, u-GaN, and buffer layer, and the overall thickness of the bonded wafer isd ₀ At this timed ₀ Is far greater thanλ，After the thinning treatment in the step (a), removing the buffer layer and the u-GaN, thinning the n-GaN layer, and keeping the thickness of the p-GaN layer, the MQW layer and the n-GaN layer to be the samed _1， It is composed ofλIs greater thand ₁ (ii) a Then, performing electron deposition on the electrode to obtain a film with a thickness ofd ₁ When V is the sub-wavelength ideal vertical structure LED>V _turn-on The LED device with the ideal sub-wavelength vertical structure has the phenomenon of coexistence of luminescence detection when the device is in a starting luminescence working mode, namely the device can detect external Incident light (Incident) while emitting light, and has the characteristic of duplex transceiving. And the reflected light emittedlight can be reflected from one side of the electrodeposited layer Electrode. The number of the optical waveguide modes is greatly reduced due to the reduction of the thickness of the device, so that the waveguide modes in the ultra-thin deep ultraviolet LED are inhibited, and the ultra-thin structure is improvedThe photoelectric conversion efficiency of the deep ultraviolet LED is improved, and the response speed of the ultrathin deep ultraviolet LED device is improved.

Noun interpretation, in this description and in fig. 4: the p-GaN is the same as the p-type GaN and refers to p-type gallium nitrogen; MQW is quantum well; the n-GaN is the same as the n-type GaN and refers to n-type gallium nitrogen; u-GaN is the same as u-GaN in indication, and refers to u-GaN; buffer layer is also referred to as buffer layer; emittedlight, reflected light; incident light.

The embodiments of the present invention are disclosed as the preferred embodiments, but not limited thereto, and those skilled in the art can easily understand the spirit of the present invention and make various extensions and changes without departing from the spirit of the present invention.