阅读说明：本技术 紫外光电探测器的制备方法及紫外光电探测器 (Preparation method of ultraviolet photoelectric detector and ultraviolet photoelectric detector ) 是由 侯钧杰 尹顺政 于 2019-10-08 设计创作，主要内容包括：本发明适用于光探测器技术领域,提供了一种紫外光电探测器的制备方法及紫外光电探测器,该制备方法包括：在预设衬底上依次生长缓冲层、P型欧姆接触层、倍增层、电荷层、吸收层以及N型欧姆接触层；光刻刻蚀倍增层、电荷层、吸收层以及N型欧姆接触层,分别在P型欧姆接触层上、电荷层上以及吸收层上形成台面结构；在P型欧姆接触层以及N型欧姆接触层上分别淀积形成接触电极；在P型欧姆接触层上、电荷层上以及吸收层上形成的台面结构的表面进行钝化膜淀积钝化,并光刻刻蚀接触电极上的钝化膜以露出电极,获得紫外光电探测器。本发明中P型欧姆接触层的接触面积大大增加,可有效减小接触电阻。(The invention is suitable for the technical field of photodetectors, and provides a preparation method of an ultraviolet photodetector and the ultraviolet photodetector, wherein the preparation method comprises the following steps: sequentially growing a buffer layer, a P-type ohmic contact layer, a multiplication layer, a charge layer, an absorption layer and an N-type ohmic contact layer on a preset substrate; photoetching and etching the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer to form a mesa structure on the P-type ohmic contact layer, the charge layer and the absorption layer respectively; respectively depositing and forming contact electrodes on the P-type ohmic contact layer and the N-type ohmic contact layer; and carrying out passivation film deposition and passivation on the surfaces of the mesa structures formed on the P-type ohmic contact layer, the charge layer and the absorption layer, and photoetching the passivation film on the contact electrode to expose the electrode to obtain the ultraviolet photoelectric detector. The contact area of the P-type ohmic contact layer is greatly increased, and the contact resistance can be effectively reduced.)

1. A method for manufacturing an ultraviolet photodetector is characterized by comprising the following steps:

sequentially growing a buffer layer, a P-type ohmic contact layer, a multiplication layer, a charge layer, an absorption layer and an N-type ohmic contact layer on a preset substrate;

photoetching and etching the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer to form a mesa structure on the P-type ohmic contact layer, the charge layer and the absorption layer respectively;

depositing contact electrodes on the P-type ohmic contact layer and the N-type ohmic contact layer respectively;

and carrying out passivation film deposition and passivation on the surfaces of the mesa structures formed on the P-type ohmic contact layer, the charge layer and the absorption layer, and photoetching the passivation film on the contact electrode to expose the electrode to obtain the ultraviolet photoelectric detector.

2. The method for manufacturing the ultraviolet photodetector of claim 1, wherein the sequentially growing the buffer layer, the P-type ohmic contact layer, the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer on the predetermined substrate comprises:

an aluminum nitride (AlN) buffer layer, a P-gallium nitride (GaN)/aluminum gallium nitride (AlGaN) ohmic contact layer, a multiplication layer with a superlattice structure, an N-AlGaN charge layer, an i-GaN/AlGaN absorption layer and an N-GaN/AlGaN ohmic contact layer are sequentially grown on a sapphire substrate or an aluminum nitride substrate.

3. The method of manufacturing an ultraviolet photodetector according to claim 2, wherein the superlattice structure is a superlattice structure in which wide and narrow gaps of GaN/AlGaN system are alternated.

4. The ultraviolet photodetector of claim 3The superlattice structure is i-AI which grows in the P-type ohmic contact layer in turn by adopting a metal organic chemical vapor deposition system_x2GaN、i-AI_x1GaN、i-AI_x2GaN and i-AI_x1And GaN, forming a superlattice structure with alternating wide and narrow gaps.

5. The method for manufacturing the ultraviolet photodetector according to any one of claims 1 to 4, wherein the photolithography etches the multiplication layer, the charge layer, the absorption layer, and the N-type ohmic contact layer to form a mesa structure on the P-type ohmic contact layer, the charge layer, and the absorption layer, respectively, and comprises:

photoresist is adopted to be used as a mask on the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer, plasma etching is carried out on the P-type ohmic contact layer, two ends of the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer are vertical to the surface of the P-type ohmic contact layer, and a first mesa structure is formed on the P-type ohmic contact layer;

adopting photoresist as a mask on the absorption layer and the N-type ohmic contact layer, etching the absorption layer and the N-type ohmic contact layer onto the charge layer by plasma, enabling two ends of the absorption layer and the N-type ohmic contact layer to be vertical to the surface of the charge layer, and forming a second mesa structure on the charge layer;

adopting photoresist to mask the multiplication layer and the charge layer, and carrying out plasma etching on the multiplication layer and the charge layer to form a slope at two ends;

and masking the N-type ohmic contact layer by adopting photoresist, etching the N-type ohmic contact layer onto the absorption layer by plasma, enabling two ends of the N-type ohmic contact layer to be vertical to the surface of the absorption layer, and forming a third mesa structure on the absorption layer.

6. The method of claim 5, wherein the slope-shaped sidewalls respectively etched at the two ends of the multiplication layer and the charge layer form an inclination angle of 50 ° to 80 ° with the surface of the P-type ohmic contact layer.

7. The method for manufacturing the ultraviolet photodetector as claimed in claim 1 or 6, wherein the depositing and forming contact electrodes on the P-type ohmic contact layer and the N-type ohmic contact layer respectively comprises:

respectively manufacturing electrode contact patterns at the positions, which are not covered by the multiplication layer, of two ends of the P-type ohmic contact layer by adopting a semiconductor photoetching process, and depositing by using an electron beam evaporation system to form P-type ohmic contact electrodes;

and manufacturing an electrode contact pattern on the surface of the N-type ohmic contact layer by adopting a semiconductor photoetching process, and depositing by using an electron beam evaporation system to form an N-type ohmic contact electrode.

8. The method for manufacturing an ultraviolet photodetector as claimed in claim 1 or 6, wherein the material of the passivation film is silicon dioxide or silicon nitride, and the thickness of the passivation film is 100nm to 1000 nm.

9. The method of manufacturing the ultraviolet photodetector according to claim 2, wherein the AI component content in the AlN buffer layer, the P-GaN/AlGaN ohmic contact layer, the multiplication layer of the superlattice structure, the N-AlGaN charge layer, the i-GaN/AlGaN absorption layer, and the N-GaN/AlGaN ohmic contact layer is more than 45%.

10. An ultraviolet photodetector, comprising: the ultraviolet photodetector manufactured by the method for manufacturing an ultraviolet photodetector according to any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of photodetectors, and particularly relates to a preparation method of an ultraviolet photoelectric detector and the ultraviolet photoelectric detector.

Background

The ultraviolet detection technology is a novel photoelectric detection technology and can be applied to the fields of accurate guidance, ultraviolet high-confidentiality communication, environmental pollution monitoring, biological analysis, astronomy, flame detection and the like. Gallium nitride (GaN) and series materials thereof are used as third-generation semiconductors, have the advantages of large forbidden bandwidth and wide spectral range, and have great application value in the field of photoelectronics. The GaN-based ternary alloy AlGaN has the characteristics of large forbidden band width, good heat conduction performance, high electron saturation drift velocity, excellent chemical stability and the like, can be used for high-temperature-resistant and high-efficiency high-frequency high-power devices, and can work in an ultraviolet band. In addition, AlGaN belongs to a direct band gap semiconductor, the band gap can continuously change between 3.4eV and 6.2eV along with the change of Al components, and the light absorption wavelength corresponding to the band gap changes from 200nm to 365 nm. The AlGaN avalanche photodiode with high Al content has natural solar blind performance and can detect weak ultraviolet signals under the background of strong solar radiation, so that AlGaN is one of ideal materials for manufacturing an ultraviolet detector.

However, the AlGaN avalanche photodiode has a problem of large ohmic contact resistance.

Disclosure of Invention

In view of this, embodiments of the present invention provide a method for manufacturing an ultraviolet photodetector and an ultraviolet photodetector, so as to solve the problem that an AlGaN avalanche photodiode in the prior art has a large ohmic contact resistance.

A first aspect of an embodiment of the present invention provides a method for manufacturing an ultraviolet photodetector, including:

sequentially growing a buffer layer, a P-type ohmic contact layer, a multiplication layer, a charge layer, an absorption layer and an N-type ohmic contact layer on a preset substrate;

photoetching and etching the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer to form a mesa structure on the P-type ohmic contact layer, the charge layer and the absorption layer respectively;

depositing contact electrodes on the P-type ohmic contact layer and the N-type ohmic contact layer respectively;

and carrying out passivation film deposition and passivation on the surfaces of the mesa structures formed on the P-type ohmic contact layer, the charge layer and the absorption layer, and photoetching the passivation film on the contact electrode to expose the electrode to obtain the ultraviolet photoelectric detector.

In an embodiment, the sequentially growing a buffer layer, a P-type ohmic contact layer, a multiplication layer, a charge layer, an absorption layer, and an N-type ohmic contact layer on a predetermined substrate includes:

an aluminum nitride (AlN) buffer layer, a P-gallium nitride (GaN)/aluminum gallium nitride (AlGaN) ohmic contact layer, a multiplication layer with a superlattice structure, an N-AlGaN charge layer, an i-GaN/AlGaN absorption layer and an N-GaN/AlGaN ohmic contact layer are sequentially grown on a sapphire substrate or an aluminum nitride substrate.

In one embodiment, the superlattice structure is a superlattice structure with alternating wide and narrow gaps of GaN/AlGaN series.

In one embodiment, the superlattice structure is i-AI formed by sequentially growing on the P-type ohmic contact layer by using a metal organic chemical vapor deposition system_x2GaN、i-AI_x1GaN、i-AI_x2GaN and i-AI_x1And GaN, forming a superlattice structure with alternating wide and narrow gaps.

In an embodiment, the lithographically etching the multiplication layer, the charge layer, the absorption layer, and the N-type ohmic contact layer to form a mesa structure on the P-type ohmic contact layer, the charge layer, and the absorption layer, respectively, includes:

photoresist is adopted to be used as a mask on the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer, plasma etching is carried out on the P-type ohmic contact layer, two ends of the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer are vertical to the surface of the P-type ohmic contact layer, and a first mesa structure is formed on the P-type ohmic contact layer;

adopting photoresist as a mask on the absorption layer and the N-type ohmic contact layer, etching the absorption layer and the N-type ohmic contact layer onto the charge layer by plasma, enabling two ends of the absorption layer and the N-type ohmic contact layer to be vertical to the surface of the charge layer, and forming a second mesa structure on the charge layer;

adopting photoresist to mask the multiplication layer and the charge layer, and carrying out plasma etching on the multiplication layer and the charge layer to form a slope at two ends;

and masking the N-type ohmic contact layer by adopting photoresist, etching the N-type ohmic contact layer onto the absorption layer by plasma, enabling two ends of the N-type ohmic contact layer to be vertical to the surface of the absorption layer, and forming a third mesa structure on the absorption layer.

In an embodiment, the slope-shaped sidewalls respectively etched at the two ends of the multiplication layer and the charge layer form an inclination angle of 50 ° to 80 ° with the surface of the P-type ohmic contact layer.

In one embodiment, the depositing contact electrodes on the P-type ohmic contact layer and the N-type ohmic contact layer respectively includes:

respectively manufacturing electrode contact patterns at the positions, which are not covered by the multiplication layer, of two ends of the P-type ohmic contact layer by adopting a semiconductor photoetching process, and depositing by using an electron beam evaporation system to form P-type ohmic contact electrodes;

and manufacturing an electrode contact pattern on the surface of the N-type ohmic contact layer by adopting a semiconductor photoetching process, and depositing by using an electron beam evaporation system to form an N-type ohmic contact electrode.

In one embodiment, the material of the passivation film is silicon dioxide or silicon nitride, and the thickness of the passivation film is 100nm to 1000 nm.

In one embodiment, the AI component content in the AlN buffer layer, the P-GaN/AlGaN ohmic contact layer, the multiplication layer of the superlattice structure, the N-AlGaN charge layer, the i-GaN/AlGaN absorption layer, and the N-GaN/AlGaN ohmic contact layer is greater than 45%.

A second aspect of an embodiment of the present invention provides an ultraviolet photodetector, including: the ultraviolet photoelectric detector is prepared by adopting the preparation method of the ultraviolet photoelectric detector in any embodiment.

Compared with the prior art, the embodiment of the invention has the following beneficial effects: by sequentially growing the buffer layer, the P-type ohmic contact layer, the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer on the preset substrate, the contact area of the P-type ohmic contact layer is greatly increased, and the contact resistance can be effectively reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a schematic flow chart of an implementation of a method for manufacturing an ultraviolet photodetector according to an embodiment of the present invention;

fig. 2 is a schematic cross-sectional view of each layer structure of the ultraviolet photodetector provided in the embodiment of the present invention;

fig. 3(1) is a schematic diagram illustrating formation of a first mesa structure according to an embodiment of the present invention;

fig. 3(2) is a diagram illustrating a second mesa structure according to an embodiment of the present invention;

fig. 3(3) is a schematic diagram illustrating ramp formation according to an embodiment of the present invention;

fig. 3(4) is a schematic diagram illustrating formation of a third mesa structure according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a contact electrode formation provided by an embodiment of the present invention;

fig. 5 is a schematic diagram of passivation layer formation according to an embodiment of the invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

In order to explain the technical means of the present invention, the following description will be given by way of specific examples.

Fig. 1 is a schematic diagram of a method for manufacturing an ultraviolet photodetector according to an embodiment of the present invention, which is described in detail below.

Step 101, growing a buffer layer, a P-type ohmic contact layer, a multiplication layer, a charge layer, an absorption layer and an N-type ohmic contact layer on a preset substrate in sequence.

Alternatively, as shown in fig. 2, the predetermined substrate may be a sapphire substrate or an aluminum nitride substrate. The method comprises the step of growing an aluminum nitride (AlN) buffer layer, a P-gallium nitride (GaN)/aluminum gallium nitride (AlGaN) ohmic contact layer, a multiplication layer with a superlattice structure, an N-AlGaN charge layer, an i-GaN/AlGaN absorption layer and an N-GaN/AlGaN ohmic contact layer on a sapphire substrate or an aluminum nitride substrate in sequence. Optionally, the AlN buffer layer, the P-GaN/AlGaN ohmic contact layer, the multiplication layer of the superlattice structure, the N-AlGaN charge layer, the i-GaN/AlGaN absorption layer, the N-GaN/AlGaN ohmic contact layer and other layers are made of GaN/AlGaN films, so that the growth process and the processing technology of the device structure can be simplified, the radiation resistance of the device is improved, the size of the device is reduced, and the cost is reduced. In addition, aiming at the characteristics of difficult P-type GaN/AlGaN ohmic contact and large contact resistance in the prior art, the contact area is greatly increased with the P-type ohmic contact layer below in the embodiment, the contact resistivity is a certain value, and when the contact area is increased, the contact resistance is reduced, so the embodiment can effectively reduce the contact resistance.

Optionally, the AI component content in the AlN buffer layer, the P-GaN/AlGaN ohmic contact layer, the multiplication layer of the superlattice structure, the N-AlGaN charge layer, the i-GaN/AlGaN absorption layer, and the N-GaN/AlGaN ohmic contact layer is greater than 45%, and when the AI component content is greater than 45%, ultraviolet detection can be achieved under normal incidence or back incidence conditions, so that solar blind detection can be achieved. The parameters such as the specific layer thickness and the Al content of the AlN buffer layer, the P-GaN/AlGaN ohmic contact layer, the multiplication layer of the superlattice structure, the N-AlGaN charge layer, and the i-GaN/AlGaN absorption layer are related to specific application requirements, and the parameters such as the layer thickness and the Al content are not limited in the present application.

Optionally, the superlattice structure is a superlattice structure with alternating wide and narrow gaps of GaN/AlGaN. Optionally, the superlattice structure is formed by applying metal organic compound on the P-type ohmic contact layeri-AI grown in sequence by chemical vapor deposition system_x2GaN、i-AI_x1GaN、i-AI_x2GaN and i-AI_x1GaN, forming a superlattice structure with alternating wide and narrow bandgaps, wherein x1>x2 or, x1<x 2. The design of the multiplication layer with the wide-band-gap superlattice structure formed by the materials with the high Al component and the low Al component in an alternating mode can effectively improve the gain of the chip.

And 102, photoetching the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer to form a mesa structure on the P-type ohmic contact layer, the charge layer and the absorption layer respectively.

Optionally, after each layer is grown on the substrate, an etching operation is performed, as shown in fig. 3(1), photoresist is used as a mask on the multiplication layer, the charge layer, the absorption layer, and the N-type ohmic contact layer, plasma etching is performed on the P-type ohmic contact layer, two ends of the multiplication layer, the charge layer, the absorption layer, and the N-type ohmic contact layer are perpendicular to the surface of the P-type ohmic contact layer, and a first mesa structure is formed on the P-type ohmic contact layer. That is, the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer have two ends within the range of two ends of the P-type ohmic contact layer, and contact electrodes may be provided at the places where the two ends of the P-type ohmic contact layer are not covered.

Optionally, as shown in fig. 3(2), photoresist is used as a mask on the absorption layer and the N-type ohmic contact layer, plasma etching is performed on the charge layer, two ends of the absorption layer and the N-type ohmic contact layer are perpendicular to the surface of the charge layer, and a second mesa structure is formed on the charge layer. Namely, the two ends of the absorption layer and the N-type ohmic contact layer are within the range of the two ends of the charge layer.

As shown in fig. 3(3), photoresist is used as a mask on the multiplication layer and the charge layer, both ends of the multiplication layer and the charge layer are plasma-etched to be in a slope shape, and optionally, the slope-shaped sidewalls respectively etched at both ends of the multiplication layer and the charge layer form an inclination angle of 50 ° to 80 ° with the surface of the P-type ohmic contact layer. Optionally, the etched inclined mesa structure in this embodiment can effectively reduce the influence of the fringe electric field on the device, improve the gain of the chip, and simplify the process.

As shown in fig. 3(4), a photoresist is used as a mask on the N-type ohmic contact layer, plasma etching is performed on the absorption layer, two ends of the N-type ohmic contact layer are perpendicular to the surface of the absorption layer, and a third mesa structure is formed on the absorption layer. Namely, two ends of the absorption layer are within the range of two ends of the N-type ohmic contact layer.

And 103, respectively depositing and forming contact electrodes on the P-type ohmic contact layer and the N-type ohmic contact layer.

Optionally, in this step, a passivation film may be etched on the P-type ohmic contact layer and the N-type ohmic contact layer to form an ohmic contact pattern, and ohmic contact metal may be evaporated and an ohmic contact electrode may be formed by lift-off or etching.

Optionally, the step may include respectively fabricating electrode contact patterns at positions where both ends of the P-type ohmic contact layer are not covered by the multiplication layer by using a semiconductor photolithography process, and depositing by using an electron beam evaporation system to form P-type ohmic contact electrodes; and manufacturing an electrode contact pattern on the surface of the N-type ohmic contact layer by adopting a semiconductor photoetching process, and depositing by using an electron beam evaporation system to form an N-type ohmic contact electrode. As shown in fig. 4, the P-type ohmic contact electrode is deposited on the P-type ohmic contact layer at the positions of both ends which are not covered; the N-type ohmic contact electrode is deposited at the middle position of the surface of the N-type ohmic contact layer.

And 104, performing passivation film deposition and passivation on the surfaces of the mesa structures formed on the P-type ohmic contact layer, the charge layer and the absorption layer, and photoetching the passivation film on the contact electrode to expose the electrode to obtain the ultraviolet photoelectric detector.

Optionally, as shown in fig. 5, the passivation film is made of silicon dioxide or silicon nitride, the thickness of the passivation film is 100nm to 1000nm, and passivation is a method for delaying the corrosion rate of metal by converting the metal surface into a state that is not easily oxidized.

According to the preparation method of the ultraviolet photoelectric detector, the buffer layer, the P-type ohmic contact layer, the multiplication layer, the charge layer, the absorption layer and the N-type ohmic contact layer are sequentially grown on the preset substrate, so that the P-type ohmic contact layer is arranged below, the contact area of the P-type ohmic contact layer is greatly increased, and the contact resistance can be effectively reduced. The multiplication layer adopts the design of a wide-band gap superlattice structure multiplication layer with alternating materials of high Al components and low Al components, so that the gain of the chip can be effectively improved. According to the structure, the GaN/AlGaN film is adopted by each layer of the P-type ohmic contact layer, the multiplication layer, the charge layer, the absorption layer, the N-type ohmic contact layer and the like, so that the growth process and the processing technology of the device structure are simplified, the radiation resistance of the device is improved, the volume of the device is reduced, and the cost is reduced. In addition, the two ends of the etching multiplication layer and the charge layer are in a slope shape, and the inclined mesa structure can effectively reduce the influence of the fringe electric field on the device, improve the gain of the chip and simplify the process.

The ultraviolet photoelectric detector provided by the embodiment can meet the requirement of an ultraviolet band photoelectric detection system by changing the content of the Al component, and has important application prospects in multiple aspects such as national defense, environmental monitoring, flame detection and the like.

It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

Corresponding to the method for manufacturing the ultraviolet photodetector described in the above embodiment, the ultraviolet photodetector provided in the embodiment of the present invention includes the ultraviolet photodetector manufactured by the method for manufacturing the ultraviolet photodetector described in any one of the above embodiments, and has the beneficial effects produced when the ultraviolet photodetector is manufactured.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.