CN117199167A - Gallium nitride device structure and preparation method thereof - Google Patents
Gallium nitride device structure and preparation method thereof Download PDFInfo
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- CN117199167A CN117199167A CN202311171509.8A CN202311171509A CN117199167A CN 117199167 A CN117199167 A CN 117199167A CN 202311171509 A CN202311171509 A CN 202311171509A CN 117199167 A CN117199167 A CN 117199167A
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- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 title claims abstract description 64
- 238000002360 preparation method Methods 0.000 title abstract description 8
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Abstract
The application provides a gallium nitride device structure device and a preparation method thereof. The gallium nitride device structure includes: a substrate; a channel layer located on the surface of the substrate; a barrier layer located on a surface of the channel layer remote from the substrate; the barrier layer is internally provided with a groove which exposes part of the surface of the channel layer; a first electrode which is positioned on the surface of the channel layer far away from the substrate and is positioned on one side of the barrier layer; the second electrode is positioned on the surface of the channel layer, which is far away from the substrate, and is positioned on one side of the barrier layer, which is far away from the first electrode; the dielectric layer is at least positioned in the groove; and the third electrode is positioned on the surface of the dielectric layer far away from the channel layer. According to the application, the grooves are formed in the barrier layer, and the grooves can exhaust two-dimensional electron gas in the channel, so that dark current is reduced, and power loss is reduced; meanwhile, when the gallium nitride device structure is irradiated by ultraviolet light, photo-generated carriers are generated in the depleted channel to form photocurrent, so that the detection efficiency is improved.
Description
Technical Field
The application relates to the technical field of semiconductors, in particular to a gallium nitride device structure and a preparation method thereof.
Background
Ultraviolet light detectors have been widely used in the fields of aerospace, sensors, flame detection, and the like. Among various materials for ultraviolet detection, high electron mobility devices (High electron mobility transistors, HEMTs) have remarkable advantages in high-precision ultraviolet photoelectric detection due to excellent ultraviolet responsivity and photocurrent density, and are increasingly used in the field of ultraviolet detection.
Because of the spontaneously formed two-dimensional electron gas in the high electron mobility device, the dark current of the high electron mobility device is high due to the existence of the two-dimensional electron gas, so that the power loss of the high electron mobility device is overlarge and the detection rate is low.
Disclosure of Invention
The application aims to provide a gallium nitride device structure and a preparation method thereof, which solve the problems of high dark current, overlarge power loss and lower detection rate of an ultraviolet light detector of a high electron mobility device in the prior art.
In order to achieve the purpose of the application, the application provides the following technical scheme:
in a first aspect, there is provided a gallium nitride device structure comprising:
a substrate;
a channel layer located on the surface of the substrate;
a barrier layer located on a surface of the channel layer remote from the substrate; a groove is formed in the barrier layer, and part of the surface of the channel layer is exposed by the groove;
a first electrode located on a surface of the channel layer away from the substrate and on one side of the barrier layer;
a second electrode located on a surface of the channel layer away from the substrate and on a side of the barrier layer away from the first electrode;
the dielectric layer is at least positioned in the groove;
and the third electrode is positioned on the surface of the dielectric layer, which is far away from the channel layer.
In one embodiment, the dielectric layer extends from within the recess to a surface of the barrier layer remote from the channel layer.
In one embodiment, the channel layer comprises a gallium nitride layer; the barrier layer comprises an aluminum gallium nitride layer; the third electrode includes an indium tin oxide transparent electrode.
In a second aspect, the present application further provides a method for preparing a gallium nitride device structure, where the method for preparing a gallium nitride device structure includes:
providing a high electron mobility device comprising: the semiconductor device comprises a substrate, a channel layer, a barrier layer, a first electrode and a second electrode; the channel layer is positioned on the surface of the substrate; the barrier layer is positioned on the surface of the channel layer away from the substrate; the first electrode is positioned on the surface of the channel layer away from the substrate and is positioned on one side of the barrier layer; the second electrode is positioned on the surface of the channel layer away from the substrate and is positioned on one side of the barrier layer away from the first electrode;
forming a groove in the barrier layer, wherein the groove exposes part of the surface of the channel layer;
forming a dielectric layer, wherein the dielectric layer is at least positioned in the groove;
and forming a third electrode on the surface of the dielectric layer far away from the barrier layer.
In one embodiment, the forming a recess in the barrier layer includes:
forming a patterned mask layer on the surface of the barrier layer far away from the channel layer, the surface of the first electrode far away from the channel layer and the surface of the second electrode far away from the channel layer, wherein an opening is formed in the patterned mask layer, and the shape and the position of the groove are defined by the opening;
and etching the barrier layer based on the patterned mask layer to form the groove in the barrier layer.
In one embodiment, the etching the barrier layer based on the patterned mask layer to form the recess in the barrier layer includes:
placing the obtained structure in an oxygen atmosphere for thermal oxidation;
and carrying out wet etching on the thermally oxidized barrier layer by using a wet etching solution so as to form the groove in the barrier layer.
In one embodiment, the channel layer comprises a gallium nitride layer, the barrier layer comprises an aluminum gallium nitride layer, the third electrode comprises an indium tin oxide transparent electrode, and the wet etching solution comprises a potassium hydroxide solution.
In one embodiment, the high electron mobility device further comprises a cap layer located on a surface of the barrier layer remote from the channel layer; the opening exposes the cap layer; the etching the barrier layer based on the patterned mask layer to form the groove in the barrier layer further comprises:
and removing the cap layer.
In one embodiment, the channel layer comprises a gallium nitride layer, the barrier layer comprises an aluminum gallium nitride layer, the third electrode comprises an indium tin oxide transparent electrode, and the cap layer comprises a gallium nitride cap layer; and etching to remove the cap layer by adopting a dry etching process, wherein etching gas used by the dry etching process comprises fluorine-based gas.
In one embodiment, the dielectric layer further extends from within the channel to a surface of the barrier layer remote from the channel layer.
The gallium nitride device structure and the preparation method thereof provided by the application have the following beneficial effects:
in the gallium nitride device structure, the grooves are formed in the barrier layer, and the grooves can exhaust two-dimensional electron gas in the channel, so that dark current is reduced, and power loss is reduced; meanwhile, when the gallium nitride device structure is irradiated by ultraviolet light, photo-generated carriers are generated in the depleted channel to form photocurrent, so that the detection efficiency is improved.
In the preparation method of the gallium nitride device structure, the grooves are formed in the barrier layer, and the grooves can exhaust two-dimensional electron gas in the channel, so that dark current is reduced, and power loss is reduced; meanwhile, when the gallium nitride device structure is irradiated by ultraviolet light, photo-generated carriers are generated in the depleted channel to form photocurrent, so that the detection efficiency is improved.
Drawings
Fig. 1 is a schematic cross-sectional view of a gallium nitride device structure according to an embodiment;
fig. 2 is a flow chart of a method of fabricating a gallium nitride device structure in another embodiment;
fig. 3 is a schematic cross-sectional structure of a structure obtained in step S11 in a method for manufacturing a gallium nitride device structure according to another embodiment;
fig. 4 is a schematic cross-sectional structure of a structure obtained in step S12 in a method for manufacturing a gallium nitride device structure according to another embodiment;
fig. 5 is a schematic cross-sectional structure of a structure obtained in step S13 in a method for manufacturing a gallium nitride device structure according to another embodiment;
fig. 6 is a schematic cross-sectional structure of a structure obtained in step S14 in a method for manufacturing a gallium nitride device structure according to another embodiment.
Description of the reference numerals
10. A substrate; 20. a channel layer; 30. a barrier layer; 301. a groove; 40. a first electrode; 50. a second electrode; 60. a dielectric layer; 70. and a third electrode.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.
In order that those skilled in the art will better understand the present application, a technical solution in an embodiment of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiment of the present application, and it is apparent that the described embodiment is only a part of the embodiment of the present application, but not all the embodiments. All other embodiments, based on the embodiments of the application, which a person skilled in the art would obtain without making any inventive effort, are within the scope of the application.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the application herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus. The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
Ultraviolet light detectors have been widely used in the fields of aerospace, sensors, flame detection, and the like. Among the various materials used for uv detection, gallium nitride (GaN) device structures are one of the most advantageous competitors for their wide band gap, large uv absorption coefficient, excellent chemical stability and high carrier mobility. Gallium nitride high electron mobility devices have significant advantages in high-precision ultraviolet photoelectric detection due to excellent ultraviolet light responsiveness and photocurrent density, and are increasingly used in the field of ultraviolet light detection.
The spontaneous formation of two-dimensional electron gas exists in the gallium nitride high-electron mobility device, so that the dark current of the device is high, excessive power loss is caused, and the detection rate is reduced. There are two ways to solve dark current in gallium nitride high electron mobility devices: the principle of the P-type gallium nitride device structure is that the dark current is reduced by preparing the P-type gallium nitride device on a high electron mobility device and exhausting two-dimensional electron gas in a channel; when the device is under ultraviolet irradiation, photo-generated carriers are generated in the depleted channel to form photocurrent, so that photoelectric detection is performed; however, the gallium nitride layer of the P-type gallium nitride device structure absorbs ultraviolet light, reducing the efficiency of photoelectric detection. The other is a groove type gallium nitride high electron mobility device structure, the principle is that chlorine-based gas such as carbon tetrachloride is used as etching gas for dry etching, an AlGaN layer is removed, two-dimensional electron gas in a channel of an etching area is exhausted, and the effect of reducing dark current is achieved; when the device is under ultraviolet irradiation, photo-generated carriers are generated in the depleted channel to form photocurrent, so that photoelectric detection is performed. However, since the etching rate of chlorine-based gases such as carbon tetrachloride is greatly changed, the difference of etching depths of different areas is obvious, the etching depth of a groove is difficult to accurately control, the etching uniformity is poor, and the AlGaN layer is difficult to accurately control and just remove, so that over etching or under etching can be caused, channel damage can be caused by over etching, the performance of a device is influenced, and under etching cannot achieve the effect of reducing dark current.
Referring to fig. 1, the present application provides a gallium nitride device structure, which may include: a substrate 10; a channel layer 20, the channel layer 20 being located on the surface of the substrate 10; a barrier layer 30, the barrier layer 30 being located on a surface of the channel layer 20 remote from the substrate 10; the barrier layer 30 has a groove 301 therein, and the groove 301 exposes a part of the surface of the channel layer 20; a first electrode 40, the first electrode 40 being located on a surface of the channel layer 20 remote from the substrate 10 and on one side of the barrier layer 30; a second electrode 50, the second electrode 50 being located on a surface of the channel layer 20 remote from the substrate 10, and on a side of the barrier layer 30 remote from the first electrode 40; a dielectric layer 60, the dielectric layer 60 being at least within the recess 301; and a third electrode 70, the third electrode 70 being located on a surface of the dielectric layer 60 remote from the channel layer 20.
In the gallium nitride device structure, the groove 301 is formed in the barrier layer 30, so that the groove 301 can exhaust two-dimensional electron gas in the channel layer 20, thereby reducing dark current and power loss; meanwhile, when the gallium nitride device structure is irradiated by ultraviolet light, photo-generated carriers are generated in the depleted channel layer 20 to form photocurrent, so that the detection efficiency is improved.
As an example, the substrate 10 may include, but is not limited to, at least one of a silicon substrate, a gallium nitride (GaN) substrate, a silicon carbide (SiC) substrate, a sapphire substrate, a silicon-on-insulator (SOI, silicon On Insulator) substrate, a silicon-on-diamond (SOD, silicon on diamond) substrate, and a strained layer silicon substrate deposited on a silicon-germanium wafer.
As an example, the channel layer 20 is located on the surface of the substrate 10; the channel layer 20 may include, but is not limited to, a layer of gallium nitride, which is a third generation wide bandgap semiconductor material having characteristics of large bandgap, high electron saturation velocity, high breakdown field, high thermal conductivity, corrosion resistance, and radiation resistance.
As an example, the barrier layer 30 is located on a surface of the channel layer 20 remote from the substrate 10; barrier layer 30 may include, but is not limited to, an aluminum gallium nitride layer; the channel layer 20 and the barrier layer 30 are in contact to form a heterostructure, the barrier layer 30 having a recess 301 therein, the recess 301 exposing a portion of the surface of the channel layer 20.
Specifically, the shape of the groove 301 may be set according to actual needs, the groove 301 may be a strip-shaped structure, a circular structure, a square structure, an oval structure, or other shaped structures, and the width of the groove 301 may be 1 μm to 10 μm, for example, the width of the groove 301 may be 1 μm, 5 μm, or 10 μm, or the like.
As an example, the first electrode 40 is located at a surface of the channel layer 20 remote from the substrate 10, and is located at one side of the barrier layer 30; the material of the first electrode 40 may be, but is not limited to, metal, and the metal may include, but is not limited to, at least one of copper, titanium, aluminum, gold, etc.; ohmic contact can be formed at the interface of the first electrode 40 and the channel layer 20, no significant additional resistance is created, and no significant change in the equilibrium carrier concentration within the gallium nitride device occurs.
As an example, the second electrode 50 is located on a surface of the channel layer 20 remote from the substrate 10, and on a side of the barrier layer 30 remote from the first electrode 40; the material of the second electrode 50 may be, but is not limited to, metal, and the metal may include, but is not limited to, at least one of copper, titanium, aluminum, gold, etc.; ohmic contact can be formed at the interface of the second electrode 50 and the channel layer 20, without creating significant additional resistance and without significantly changing the equilibrium carrier concentration within the gallium nitride device.
As an example, dielectric layer 60 is located at least within recess 301; the material of the dielectric layer 60 may include, but is not limited to, an insulator, for example, the material of the dielectric layer 60 may include, but is not limited to, aluminum oxide (Al 2 O 3 ) Silicon oxide (SiO) x ) Silicon nitride (SiN) x ) Or silicon oxynitride (SiON) and the like; specifically, in the present embodiment, the dielectric layer 60 is a silicon nitride layer, and the silicon nitride has a low dielectric constant, and at the same time, the resistivity can reach as high as 10++14Ω·cm, which can perform a good insulating function, and can block the diffusion of impurities.
As an example, dielectric layer 60 may extend from within recess 301 to a surface of barrier layer 30 remote from channel layer 20.
As an example, the thickness of the dielectric layer 60 may be less than the depth of the recess 301 and less than half the width of the recess 301.
As an example, the third electrode 70 may include, but is not limited to, an Indium Tin Oxide (ITO) transparent electrode; the indium tin oxide transparent electrode is indium oxide (In 2 O 3 ) Contains a small amount of tin dioxide (SnO) 2 ) The mass ratio of indium oxide to tin dioxide may be, but is not limited to, 90% and 10%; the transparent electrode of indium tin oxide has excellent conductivity, and from microscopic analysis, it can be described that after tin is doped into indium oxide, tin element can replace indium element in indium oxide crystal lattice to exist in the form of tin dioxide, because the indium element in indium oxide is trivalent, when tin dioxide is formed, one electron is contributed to conduction band, and oxygen hole is generated under certain oxygen deficiency state to form 1020-1021 cm -3 Carrier concentration of 10-30 cm 2 Mobility of/(V.s).
The third electrode 70 of the application adopts an indium tin oxide transparent electrode, does not absorb ultraviolet light, and can improve the light detection responsivity and detection rate of the gallium nitride device structure.
Referring to fig. 2, the present application provides a method for preparing a gallium nitride device structure, which may include the following steps:
step S11: providing a high electron mobility device, the high electron mobility device may include: the semiconductor device comprises a substrate, a channel layer, a barrier layer, a first electrode and a second electrode; the channel layer is positioned on the surface of the substrate; the barrier layer is positioned on the surface of the channel layer far away from the substrate; the first electrode is positioned on the surface of the channel layer far away from the substrate and is positioned on one side of the barrier layer; the second electrode is positioned on the surface of the channel layer, which is far away from the substrate, and is positioned on one side of the barrier layer, which is far away from the first electrode;
step S12: forming a groove in the barrier layer, wherein the groove exposes part of the surface of the channel layer;
step S13: forming a dielectric layer, wherein the dielectric layer is at least positioned in the groove;
step S14: and forming a third electrode on the surface of the dielectric layer away from the barrier layer.
In the preparation method of the gallium nitride device structure, the grooves are formed in the barrier layer, and the grooves can exhaust two-dimensional electron gas in the channel, so that dark current is reduced, and power loss is reduced; meanwhile, when the gallium nitride device structure is irradiated by ultraviolet light, photo-generated carriers are generated in the depleted channel to form photocurrent, so that the detection efficiency is improved.
In step S11, referring to step S11 in fig. 2 and fig. 3, a high electron mobility device is provided, and the high electron mobility device may include: a substrate 10, a channel layer 20, a barrier layer 30, a first electrode 40, and a second electrode 50; the channel layer 20 is located on the surface of the substrate 10; the barrier layer 30 is located on the surface of the channel layer 20 remote from the substrate 10; the first electrode 40 is located on the surface of the channel layer 20 away from the substrate 10 and on one side of the barrier layer 30; the second electrode 50 is located on a surface of the channel layer 20 remote from the substrate 10, and on a side of the barrier layer 30 remote from the first electrode 40.
As an example, the substrate 10 may include, but is not limited to, at least one of a silicon substrate, a gallium nitride substrate, a silicon carbide substrate, a sapphire substrate, a silicon-on-insulator substrate, a silicon-on-diamond substrate, and a strained layer silicon substrate deposited on a silicon-germanium wafer.
As an example, the channel layer 20 may include, but is not limited to, a gallium nitride layer, which is a third generation wide bandgap semiconductor material having characteristics of a large bandgap, a high electron saturation rate, a high breakdown field, a high thermal conductivity, corrosion resistance, and radiation resistance.
As an example, barrier layer 30 may include, but is not limited to, an aluminum gallium nitride layer; the channel layer 20 and the barrier layer 30 are in contact to form a heterostructure.
As an example, the material of the first electrode 40 may be, but is not limited to, metal, and the metal may include, but is not limited to, at least one of copper, titanium, aluminum, gold, etc.; ohmic contact can be formed at the interface of the first electrode 40 and the channel layer 20, no significant additional resistance is created, and no significant change in the equilibrium carrier concentration within the gallium nitride device occurs.
As an example, the material of the second electrode 50 may be, but is not limited to, metal, and the metal may include, but is not limited to, at least one of copper, titanium, aluminum, gold, etc.; ohmic contact can be formed at the interface of the second electrode 50 and the channel layer 20, without creating significant additional resistance and without significantly changing the equilibrium carrier concentration within the gallium nitride device.
As an example, the epitaxial growth method of the channel layer 20 may include, but is not limited to, a hydride vapor phase epitaxy process, a metal organic chemical vapor deposition process, a molecular beam epitaxy process, or other growth methods.
By way of example, the epitaxial growth method of the barrier layer 30 may include, but is not limited to, a metal organic chemical vapor deposition process, a molecular beam epitaxy process, or other growth methods.
As an example, the forming method of the first electrode 40 and the second electrode 50 may include the steps of:
etching the barrier layer 30 and the channel layer 20 so that the channel layer 20 forms a boss (not shown), the barrier layer 30 being located on a surface of the boss remote from the substrate 10; specifically, the barrier layer 30 and the channel layer 20 may be etched by a dry etching process, so that the channel layer 20 forms a boss;
forming electrode material layers (not shown) on the surfaces of the channel layer 20 and the barrier layer 30, which are exposed on the opposite sides of the boss, and away from the surface of the channel layer 20; specifically, the electrode material layer may be formed by, but not limited to, a process such as electroplating;
removing the electrode material layer on the surface of the barrier layer 30 far from the channel layer 20 to form a first electrode 40 and a second electrode 50; specifically, but not limited to, a chemical mechanical polishing process may be used to remove the electrode material layer on the surface of the barrier layer 30 remote from the channel layer 20.
In step S12, referring to step S12 in fig. 2 and fig. 4, a groove 301 is formed in the barrier layer 30, and the groove 301 exposes a portion of the surface of the channel layer 20.
As an example, in step S12, forming the recess 301 in the barrier layer 30 may include the following steps:
s121: forming a patterned mask layer (not shown) on the surface of the barrier layer 30 away from the channel layer 20, the surface of the first electrode 40 away from the channel layer 20, and the surface of the second electrode 50 away from the channel layer 20, wherein the patterned mask layer has openings therein, and the openings define the shape and position of the grooves 301;
s122: the barrier layer 30 is etched based on the patterned mask layer to form a recess 301 in the barrier layer 30.
As an example, the patterned mask layer may be obtained by a photolithography, a photolithography and wet etching process, or a photolithography and dry etching process; the patterned mask layer can be a single-layer structure or a multi-layer structure, and the patterned mask layer can be made of a photoresist layer, a metal mask layer, a metal alloy mask layer, a silicon-based oxide mask layer (for example, a silicon dioxide layer), a silicon-based nitride mask layer, a metal oxide mask layer or a metal nitride mask layer. The thickness of the patterned mask layer may be, but is not limited to, 10nm to 1000nm; specifically, in this embodiment, the patterned mask layer has a single-layer structure, and the patterned mask layer may include a photoresist layer, and a photolithography process is used to form the patterned mask layer; the thickness of the patterned mask layer is set according to actual needs, and in this embodiment, the thickness of the patterned mask layer may be, but is not limited to, 70-300 nm, for example, the thickness of the patterned mask layer may be 70nm, 100nm, 200nm or 300 nm.
As an example, the shape of the opening may be set according to actual needs, the opening may be in a bar-shaped structure, a circular structure, a square structure, an oval structure, or other shaped structures, and the width of the opening may be 1 μm to 10 μm, for example, may be 1 μm, 5 μm, or 10 μm.
As an example, the barrier layer 30 is etched using a wet etching process based on the patterned mask layer to form a recess 301 in the barrier layer 30;
in step S122, the barrier layer 30 is etched based on the patterned mask layer to form the recess 301 in the barrier layer 30, which may include the following steps:
s1221: placing the obtained structure in an oxygen atmosphere for thermal oxidation; thermal oxidation may include, but is not limited to, dry oxygen oxidation, water vapor oxidation, or wet oxygen oxidation; the thermal oxidation temperature and the thermal oxidation time in the thermal oxidation process of the obtained structure can be set according to actual needs, and the thermal oxidation temperature and the thermal oxidation time are not limited herein;
s1222: wet etching is performed on the thermally oxidized barrier layer 30 by using a wet etching solution to form a groove 301 in the barrier layer 30; in this embodiment, the wet etching solution may include a potassium hydroxide (KOH) solution.
Specifically, in step S122, the obtained structure may be subjected to thermal oxidation in a high-temperature oxidation environment, and the structure after thermal oxidation may be subjected to wet etching in a potassium hydroxide solution, so as to obtain the groove 301.
The application does not use a dry etching process in the process of forming the groove 301, can better control the etching precision, does not have the phenomenon of damaging the channel layer 20 and the phenomenon of underetching caused by over etching, and is suitable for large-scale commercial production and application.
As an example, the high electron mobility device may further include a cap layer (not shown) located on a surface of the barrier layer 30 remote from the channel layer 20; the opening exposes the cap layer; before etching the barrier layer 30 based on the patterned mask layer to form the recess 301 in the barrier layer 30, the method further includes the following steps: and removing the cap layer.
In particular, the cap layer may include, but is not limited to, a gallium nitride cap layer. The cap layer may be removed using a dry etching process, and in particular, the cap layer may be removed using a fluorine-based gas, which may include, but is not limited to: carbon tetrafluoride (CF) 4 ) Sulfur hexafluoride (SF) 6 ) Di-carbon hexafluoride (C) 2 F 6 ) Or nitrogen trifluoride (NF) 3 ) Etc.; the fluorine-based gas can stop on the barrier layer 30 of AlGaN during etching, and over etching can be avoided.
In step S13, referring to step S13 in fig. 2 and fig. 5, a dielectric layer 60 is formed, and the dielectric layer 60 is at least located in the recess 301.
As an example, the dielectric layer 60 may also extend from within the channel to a surface of the barrier layer 30 remote from the channel layer 20.
As an example, the thickness of the dielectric layer 60 may be less than the depth of the recess 301 and less than half the width of the recess 301.
As an example, in step S13, the dielectric layer 60 is formed, and the dielectric layer 60 is at least located in the recess 301, which may include the following steps:
s131: a dielectric material layer (not shown) is formed to cover the sidewalls of the recess 301, the bottom of the recess 301, the surface of the barrier layer 30 away from the channel layer 20, the surface of the first electrode 40 away from the channel layer 20, and the surface of the second electrode 50 away from the channel layer 20;
s132: a portion of the dielectric material layer is removed based on a photolithographic etching process to obtain dielectric layer 60.
Specifically, in step S131, the dielectric material layer may be formed by, but not limited to, a physical vapor deposition process, a chemical vapor deposition process, an atomic layer deposition process, or the like; in step S132, a portion of the dielectric material layer may be etched away by, but not limited to, a dry etching process, so as to obtain the dielectric layer 60.
By way of example, the material of dielectric layer 60 may include, but is not limited to, an insulator, e.g., the material of dielectric layer 60 may include aluminum oxide (Al 2 O 3 ) Silicon oxide (SiO) x ) Silicon nitride (SiN) x ) Or silicon oxynitride(SiON) and the like; specifically, in the present embodiment, the dielectric layer 60 is a silicon nitride layer, and the silicon nitride has a low dielectric constant, and at the same time, the resistivity can reach as high as 10++14Ω·cm, which can perform a good insulating function, and can block the diffusion of impurities.
In step S14, referring to step S14 in fig. 2 and fig. 6, a third electrode 70 is formed on the surface of the dielectric layer 60 away from the barrier layer 30.
As an example, in step S14, forming the third electrode 70 on the surface of the dielectric layer 60 away from the barrier layer 30 may include the following steps:
s141: forming an electrode material layer, wherein the electrode material layer covers the exposed surface of the barrier layer 30 far away from the channel layer 20, the surface of the first electrode 40 far away from the channel layer 20, the surface of the second electrode 50 far away from the channel layer 20 and the dielectric layer 60; specifically, the electrode material layer may be formed using, but not limited to, an electroplating process or the like;
s142: etching the electrode material layer in step S141 by using a photolithography etching process to obtain a third electrode 70; specifically, the electrode material layer in step S141 may be etched using, but not limited to, a dry etching process to obtain the third electrode 70.
As an example, the third electrode 70 may include, but is not limited to, an Indium Tin Oxide (ITO) transparent electrode; the indium tin oxide transparent electrode is indium oxide (In 2 O 3 ) Contains a small amount of tin dioxide (SnO) 2 ) The mass ratio of indium oxide to tin dioxide may be, but is not limited to, 90% and 10%; the transparent electrode of indium tin oxide has excellent conductivity, and from microscopic analysis, it can be described that after tin is doped into indium oxide, tin element can replace indium element in indium oxide crystal lattice to exist in the form of tin dioxide, because the indium element in indium oxide is trivalent, when tin dioxide is formed, one electron is contributed to conduction band, and oxygen hole is generated under certain oxygen deficiency state to form 1020-1021 cm -3 Carrier concentration of 10-30 cm 2 Mobility of/(V.s).
The third electrode 70 of the application adopts an indium tin oxide transparent electrode, does not absorb ultraviolet light, and can improve the light detection responsivity and detection rate of the gallium nitride device structure.
The technical features of the above embodiments may be arbitrarily combined, and for brevity, all of the possible combinations of the technical features of the above embodiments are not described, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (10)
1. A gallium nitride device structure, comprising:
a substrate;
a channel layer located on the surface of the substrate;
a barrier layer located on a surface of the channel layer remote from the substrate; a groove is formed in the barrier layer, and part of the surface of the channel layer is exposed by the groove;
a first electrode located on a surface of the channel layer away from the substrate and on one side of the barrier layer;
a second electrode located on a surface of the channel layer away from the substrate and on a side of the barrier layer away from the first electrode;
the dielectric layer is at least positioned in the groove;
and the third electrode is positioned on the surface of the dielectric layer, which is far away from the channel layer.
2. The gallium nitride device structure of claim 1, wherein the dielectric layer extends from within the recess to a surface of the barrier layer remote from the channel layer.
3. The gallium nitride device structure of claim 1, wherein the channel layer comprises a gallium nitride layer; the barrier layer comprises an aluminum gallium nitride layer; the third electrode includes an indium tin oxide transparent electrode.
4. A method for fabricating a gallium nitride device structure, comprising:
providing a high electron mobility device comprising: the semiconductor device comprises a substrate, a channel layer, a barrier layer, a first electrode and a second electrode; the channel layer is positioned on the surface of the substrate; the barrier layer is positioned on the surface of the channel layer away from the substrate; the first electrode is positioned on the surface of the channel layer away from the substrate and is positioned on one side of the barrier layer; the second electrode is positioned on the surface of the channel layer away from the substrate and is positioned on one side of the barrier layer away from the first electrode;
forming a groove in the barrier layer, wherein the groove exposes part of the surface of the channel layer;
forming a dielectric layer, wherein the dielectric layer is at least positioned in the groove;
and forming a third electrode on the surface of the dielectric layer far away from the barrier layer.
5. The method of fabricating a gallium nitride device structure according to claim 4, wherein forming a recess in the barrier layer comprises:
forming a patterned mask layer on the surface of the barrier layer far away from the channel layer, the surface of the first electrode far away from the channel layer and the surface of the second electrode far away from the channel layer, wherein an opening is formed in the patterned mask layer, and the shape and the position of the groove are defined by the opening;
and etching the barrier layer based on the patterned mask layer to form the groove in the barrier layer.
6. The method of fabricating a gallium nitride device structure according to claim 5, wherein the etching the barrier layer based on the patterned mask layer to form the recess in the barrier layer comprises:
placing the obtained structure in an oxygen atmosphere for thermal oxidation;
and carrying out wet etching on the thermally oxidized barrier layer by using a wet etching solution so as to form the groove in the barrier layer.
7. The method of fabricating a gallium nitride device structure according to claim 6, wherein the channel layer comprises a gallium nitride layer, the barrier layer comprises an aluminum gallium nitride layer, the third electrode comprises an indium tin oxide transparent electrode, and the wet etching solution comprises a potassium hydroxide solution.
8. The method of fabricating a gallium nitride device structure according to claim 5, wherein the high electron mobility device further comprises a cap layer on a surface of the barrier layer remote from the channel layer; the opening exposes the cap layer; the etching the barrier layer based on the patterned mask layer to form the groove in the barrier layer further comprises:
and removing the cap layer.
9. The method of fabricating a gallium nitride device structure according to claim 8, wherein the channel layer comprises a gallium nitride layer, the barrier layer comprises an aluminum gallium nitride layer, the third electrode comprises an indium tin oxide transparent electrode, and the cap layer comprises a gallium nitride cap layer; and etching to remove the cap layer by adopting a dry etching process, wherein etching gas used by the dry etching process comprises fluorine-based gas.
10. The method of claim 4, wherein the dielectric layer further extends from within the channel to a surface of the barrier layer remote from the channel layer.
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