CN111952361A - Semiconductor device and method for manufacturing the same - Google Patents
Semiconductor device and method for manufacturing the same Download PDFInfo
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- CN111952361A CN111952361A CN202010630548.XA CN202010630548A CN111952361A CN 111952361 A CN111952361 A CN 111952361A CN 202010630548 A CN202010630548 A CN 202010630548A CN 111952361 A CN111952361 A CN 111952361A
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 12
- 238000000034 method Methods 0.000 title claims description 10
- 210000003127 knee Anatomy 0.000 claims abstract description 20
- 230000004888 barrier function Effects 0.000 claims description 62
- 239000000758 substrate Substances 0.000 claims description 24
- 230000005533 two-dimensional electron gas Effects 0.000 claims description 23
- 239000000463 material Substances 0.000 claims description 18
- 230000002457 bidirectional effect Effects 0.000 claims description 17
- 238000002161 passivation Methods 0.000 claims description 13
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- 229910002704 AlGaN Inorganic materials 0.000 claims description 5
- 229920006395 saturated elastomer Polymers 0.000 abstract description 11
- 238000004377 microelectronic Methods 0.000 abstract description 2
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 14
- 229910002601 GaN Inorganic materials 0.000 description 13
- 229910052581 Si3N4 Inorganic materials 0.000 description 6
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 6
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- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
- H01L29/861—Diodes
- H01L29/872—Schottky diodes
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- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/401—Multistep manufacturing processes
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- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
- H01L29/417—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions carrying the current to be rectified, amplified or switched
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- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/45—Ohmic electrodes
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- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
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- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
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- H01L29/66083—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
- H01L29/66196—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices with an active layer made of a group 13/15 material
- H01L29/66204—Diodes
- H01L29/66212—Schottky diodes
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Abstract
The invention relates to the technical field of microelectronics, and discloses a semiconductor device and a manufacturing method thereof. The two ends of the semiconductor device are provided with a first electrode and a second electrode, and the first electrode and the second electrode are both mixed electrodes formed by short connection of an ohmic contact electrode and a Schottky contact electrode. The depletion region under the first schottky contact electrode at the first electrode gradually expands as the voltage applied to the second electrode increases, limiting the continued increase in current due to the higher resistance of the expanded depletion region. When the voltage applied to the second electrode reaches the knee voltage, the output current of the semiconductor device tends to be saturated and reaches a certain fixed value. Similarly, when the voltage applied to the first electrode reaches the knee voltage, the output current of the semiconductor device also tends to be saturated. Therefore, by applying a forward bias voltage or a reverse bias voltage to the semiconductor device, the semiconductor device can output a constant current.
Description
Technical Field
The invention relates to the technical field of microelectronics, in particular to a semiconductor device and a manufacturing method thereof.
Background
The constant current diode has the characteristic similar to a constant current source, and has wide application in practical power systems, such as light emitting diode lighting systems, battery charging and discharging systems, telecommunication line systems and the like. Most systems requiring a constant current source can use a constant current diode. Compared with a constant current source based on an integrated circuit, the constant current diode belongs to a single transistor device and has the characteristics of simple structure, high reliability, strong anti-interference capability and the like. At present, the existing gallium nitride unidirectional constant current diode can only realize the unidirectional constant current function, but in some application fields, the device is expected to provide the bidirectional constant current function, such as driving an alternating current LED and the like. In the prior art, two constant current diodes and two common diodes are usually adopted to provide a bidirectional constant current function, so as to drive an alternating current LED to work. When the circuit voltage is positive, negative, the constant current diode and the common diode on one path are conducted to provide clockwise constant current for the circuit; when the circuit voltage is up and down and positive, the constant current diode and the common diode in the other path are conducted, and counterclockwise constant current is provided for the circuit. However, when the bidirectional constant current circuit is used for providing the bidirectional constant current function, at least four devices are needed, so that the cost is high; meanwhile, as the common diode is adopted in the circuit, a part of power consumption is additionally increased. Therefore, it is necessary to develop a two-terminal device having a bidirectional constant current function.
Disclosure of Invention
In view of the above, it is necessary to provide a semiconductor device and a method for manufacturing the same, aiming at the problem that there is no current regulator diode with bidirectional constant current function.
A semiconductor device includes a substrate; a buffer layer disposed on the substrate; a barrier layer disposed on the buffer layer on a side remote from the substrate; wherein, two-dimensional electron gas is formed at the junction of the buffer layer and the barrier layer; the first electrode and the second electrode are arranged at two ends of the barrier layer far away from one side of the buffer layer; the first electrode comprises a first ohmic contact electrode formed on the barrier layer and a first Schottky contact electrode shorted with the first ohmic contact electrode; the second electrode comprises a second ohmic contact electrode formed on the barrier layer and a second Schottky contact electrode shorted with the second ohmic contact electrode; the passivation layer is arranged on one side, far away from the buffer layer, of the barrier layer and is positioned between the first electrode and the second electrode.
The two ends of the semiconductor device are respectively provided with the first electrode and the second electrode which are formed by short circuit of the ohmic contact electrode and the Schottky contact electrode, the depletion region below the Schottky junction of the first electrode can be gradually expanded along with the increase of the voltage applied on the second electrode, and the two-dimensional electron gas channel can even be pinched off. The increased resistance of the expanded depletion region limits the current to continue to increase, thereby creating negative feedback. When the voltage applied to the second electrode reaches the knee voltage, the output current of the semiconductor device tends to be saturated and reaches a certain fixed value. Similarly, the depletion region under the Schottky junction of the second electrode gradually expands with the increase of the voltage applied on the first electrode; when the voltage applied to the first electrode reaches the knee voltage, the output current of the semiconductor device tends to saturate to a certain fixed value. Therefore, when voltages in different directions are applied to the first electrode or the second electrode of the semiconductor device, constant output currents in different directions can be obtained. The semiconductor device provided by the invention can provide bidirectional constant output current, no additional device or circuit is needed, the manufacturing cost is low, and meanwhile, the conduction power consumption of the device is also low.
In one embodiment, the barrier layer comprises a first groove and a second groove which are formed by etching on the side far away from the buffer layer; part of the first ohmic contact electrode is positioned in the first groove and is in contact with the bottom of the first groove to form a first ohmic contact structure, and part of the first Schottky contact electrode is positioned in the first groove and is in contact with the bottom of the first groove to form a first Schottky contact structure; and part of the second ohmic contact electrode is positioned in the second groove and is in contact with the bottom of the second groove to form a second ohmic contact structure, and part of the second Schottky contact electrode is positioned in the second groove and is in contact with the bottom of the second groove to form a second Schottky contact structure.
In one embodiment, the knee voltage of the semiconductor device is related to the depth of the first and second recesses.
In one embodiment, the first Schottky contact electrode and the second Schottky contact electrode are symmetrically distributed by taking a vertical middle line of the semiconductor device as an axis; the first ohmic contact electrode and the second ohmic contact electrode are also symmetrically distributed by taking a vertical middle line of the semiconductor device as an axis; the first and second Schottky contact electrodes are located between the first and second ohmic contact electrodes.
In one embodiment, the buffer layer and the barrier layer form a heterojunction.
In one embodiment, the material of the buffer layer includes GaN.
In one embodiment, the material of the barrier layer comprises AlGaN.
In one embodiment, the material of the passivation layer comprises SiN.
In one embodiment, the semiconductor device is a bidirectional constant current diode.
A semiconductor device manufacturing method comprises providing a substrate; forming a buffer layer on the substrate; forming a barrier layer on one side of the buffer layer far away from the substrate; wherein a two-dimensional electron gas is formed between the buffer layer and the barrier layer; partially etching two ends of one side of the barrier layer, which is far away from the buffer layer, to form a first groove and a second groove; forming a first electrode on the first groove and a second electrode on the second groove; the first electrode comprises a first ohmic contact electrode formed on the barrier layer and a first Schottky contact electrode shorted with the first ohmic contact electrode; the second electrode comprises a second ohmic contact electrode formed on the barrier layer and a second Schottky contact electrode shorted with the second ohmic contact electrode; and forming a passivation layer between the first electrode and the second electrode on one side of the barrier layer far away from the buffer layer.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a semiconductor device according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the operation of a semiconductor device in accordance with one embodiment of the present invention;
FIG. 3 is a graph of current-voltage characteristics of a semiconductor device in accordance with one embodiment of the present invention;
fig. 4 is a flowchart illustrating a method for fabricating a semiconductor device according to an embodiment of the present invention.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present application. The first resistance and the second resistance are both resistances, but they are not the same resistance.
It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.
The existing gallium nitride unidirectional constant current diode can only realize the function of unidirectional constant current. When forward bias voltage is applied to two ends of the gallium nitride unidirectional constant current diode, when the voltage on the anode reaches knee voltage, the anode output current tends to be saturated and reaches a certain fixed value. The anode output current does not change any more due to the action of negative feedback, and the area of the anode output current, which does not change along with the change of the bias voltage, is called the constant current area of the constant current diode. The normal working interval of the gallium nitride unidirectional constant current diode is the constant current area, and the constant current diode is similar to a constant current source at the moment. When the gan unidirectional constant current diode is in a reverse bias state, current can flow in from the cathode when the voltage is greater than the turn-on voltage of the schottky diode. With the increase of the reverse bias voltage, the current flowing from the cathode to the anode also increases all the time, that is, when the reverse bias voltage is applied to the two ends of the gan unidirectional constant current diode, the function of constant current cannot be realized.
However, in some application fields, for example, when driving an ac LED, it is desirable that the device can provide a bidirectional constant current function, and currently, a bidirectional constant current circuit is generally used to provide the bidirectional constant current function, so as to drive the ac LED (light emitting diode). When the voltage applied in the circuit is positive, negative, the upper constant current diode and the common diode are conducted to provide clockwise constant current for the circuit; when the voltage applied in the circuit goes up, down and positive, the lower constant current diode and the common diode are conducted to provide a constant current in a counterclockwise direction for the circuit. However, the bidirectional constant current circuit needs at least four devices, and the cost is high. Meanwhile, as the common diode is adopted in the circuit, a part of power consumption is additionally increased. The semiconductor device provided by the invention can provide bidirectional constant output current, does not need additional devices or circuits, is low in manufacturing cost, and is low in conduction power consumption.
Fig. 1 is a schematic structural view of a semiconductor device according to an embodiment of the present invention, which includes a substrate 100, a buffer layer 200, a barrier layer 300, a two-dimensional electron gas 400, a first electrode 510, a second electrode 520, and a passivation layer 600. The semiconductor device comprises a substrate 100, the buffer layer 200 is arranged on the substrate 100, and the barrier layer 300 is arranged on the buffer layer 200 at the side far away from the substrate 100. A two-dimensional electron gas 400 is formed at the boundary between the buffer layer 200 and the barrier layer 300. The first electrode 510 and the second electrode 520 are disposed on a side of the barrier layer 300 away from the buffer layer 200. Wherein the first electrode 510 includes a first ohmic contact electrode 511 formed on the barrier layer 300, and a first schottky contact electrode 512 shorted to the first ohmic contact electrode 511; the second electrode includes a second ohmic contact electrode 521 formed on the barrier layer 300, and a second schottky contact electrode 522 shorted to the second ohmic contact electrode 521. The passivation layer 600 is disposed on a side of the barrier layer 300 away from the buffer layer 200 and between the first electrode 510 and the second electrode 520.
The two ends of the semiconductor device provided by the invention are provided with the first electrode 510 and the second electrode 520, and the first electrode 510 and the second electrode 520 are both mixed electrodes formed by short-circuiting an ohmic contact electrode and a Schottky contact electrode. The depletion region under the first schottky contact electrode at the first electrode 510 is gradually expanded as the voltage applied to the second electrode 520 is increased, and the two-dimensional electron gas channel of the depletion region under the first schottky contact electrode is even pinched off. Since the resistance of the expanded depletion region is large, the current is restricted from increasing further, and thus negative feedback is formed. When the voltage applied to the second electrode 520 reaches the knee voltage, the output current of the semiconductor device tends to be saturated and reaches a certain fixed value. Similarly, the depletion region under the second schottky contact electrode at the second electrode 520 gradually expands with increasing voltage applied to the first electrode 510 until the two-dimensional electron gas channel of the depletion region under the second schottky contact electrode is pinched off. When the voltage applied to the first electrode 510 reaches the knee voltage, the output current of the semiconductor device tends to be saturated and reaches a certain fixed value. The semiconductor device can output a constant current by applying a forward voltage to the first electrode 510 or applying a forward voltage to the second electrode 520 of the semiconductor device. Therefore, when the semiconductor device is applied to a circuit requiring bidirectional constant current, constant output currents in different directions can be obtained.
In one embodiment, the barrier layer 300 includes a first recess and a second recess formed by etching on a side thereof away from the buffer layer 200. By performing etching processing on the side of the barrier layer 300 away from the buffer layer 200, a first groove and a second groove are formed. The first and second grooves each include an ohmic contact region and a schottky contact region. A portion of the first ohmic contact electrode 511 is located in the first groove and contacts the ohmic contact region at the bottom of the first groove to form a first ohmic contact structure. The first schottky contact electrode 512 covers the first ohmic contact electrode 511, and a portion of the first schottky contact electrode 512 is located in the first groove, and contacts with the schottky contact region at the bottom of the first groove to form a first schottky contact structure. Similarly, a portion of the second ohmic contact electrode 521 is located in the second groove and contacts the ohmic contact region at the bottom of the second groove to form a second ohmic contact structure. The second schottky contact electrode 522 covers the second ohmic contact electrode 521, and a portion of the second schottky contact electrode 522 is located in the first groove and contacts the schottky contact region at the bottom of the second groove to form a second schottky contact structure.
Ohmic contact means that when a metal is in contact with a semiconductor material, the resistance of the contact surface is much lower than the resistance of the semiconductor itself, so that most of the voltage drops in the active region but not at the contact surface when the device is in operation. In order for the device to operate at high frequencies, the on-resistance must be as low as possible. In a high frequency device, the magnitude of the on-resistance is mainly determined by the contact resistance, and therefore, in order to obtain a low on-resistance, it is necessary to ensure that the semiconductor device can operate under high frequency conditions by ohmic contact. Schottky contact refers to the bending of the semiconductor energy band at the interface when metal is in contact with the semiconductor material, forming a schottky barrier, resulting in large interface resistance. The schottky barrier refers to a metal-semiconductor contact having a rectifying characteristic as if a diode had a rectifying characteristic. Is a region with rectification action formed on the metal-semiconductor boundary, and the semiconductor device has rectification action by forming Schottky contact.
In one embodiment, the knee voltage of the semiconductor device is related to the depth of the first and second recesses. When the voltage applied to the semiconductor device reaches the knee voltage, the output current of the semiconductor device tends to saturate, reaching a certain fixed value. The knee point voltage of the semiconductor device is related to the depth of the groove, the work function of the Schottky electrode metal, the length of the groove and the etching process of the groove. Wherein the largest impact on knee voltage of the semiconductor device is the groove depth. The voltage at which the current of the semiconductor device reaches saturation is related to the depth of the groove of the schottky contact structure. The concentration of the two-dimensional electron gas can be adjusted by changing the depth of the groove, and the deeper the groove of the Schottky contact structure is, the lower the concentration of the two-dimensional electron gas below the groove is, and the current of the semiconductor device can reach a saturation state at lower voltage.
In one embodiment, the first schottky contact electrode 512 and the second schottky contact electrode 522 are symmetrically distributed around a vertical centerline of the semiconductor device. The first ohmic contact electrode 511 and the second ohmic contact electrode 521 are also symmetrically distributed with respect to a vertical center line of the semiconductor device as an axis. When the voltage applied to the two ends of the semiconductor device is 0V, no current flows through the two ends of the semiconductor device, the two-dimensional electron gas in the drift region is uniformly distributed, and the two-dimensional electron gas below the first groove is approximately uniformly distributed. Since the barrier layer 300 is partially etched to form the first groove, the two-dimensional electron gas concentration below the first groove is lower than that of the drift region. It is to be noted that the two-dimensional electron gas below the first groove and the second groove is always present, and the concentration of the two-dimensional electron gas can be adjusted by changing the groove depth. The deeper the groove, the lower the concentration of the two-dimensional electron gas below the groove.
Fig. 2 is a schematic diagram of the operation of a semiconductor device according to an embodiment of the present invention, and (a) in fig. 2 shows a carrier distribution when a negative voltage is applied to the first electrode 510 and a positive voltage is applied to the second electrode 520. When a negative voltage is applied to the first electrode 510 and a positive voltage is applied to the second electrode 520, a current flows in the device. Since the first schottky contact structure in the first electrode 510 is in a reverse bias state at this time, a current flows between the second ohmic contact structure of the second electrode 520 and the first ohmic contact structure of the first electrode 510. The current magnitude increases with increasing forward bias voltage. At the same time, the reverse bias voltage applied to the first schottky contact structure at the first electrode 510 is also increased, which causes the two-dimensional electron gas under the first schottky contact structure to be gradually depleted in the process of gradually increasing the voltage on the second electrode 520. That is, the depletion region under the first schottky contact structure gradually expands with the increase of the voltage on the second electrode 520, and the two-dimensional electron gas channel is even pinched off. Negative feedback is created because the resistance of the expanded depletion region is large, which limits the continued increase in current. When the voltage on the second electrode 520 reaches the knee voltage, the output current of the second electrode 520 tends to be saturated and reaches a certain fixed value. At this time, if the bias voltage on the second electrode 520 is continuously increased, the output current of the second electrode 520 is not changed due to the negative feedback, thereby ensuring that the semiconductor device can realize constant current output.
Since the first electrode 510 and the second electrode 520 have the same structure and are symmetrically distributed with the vertical centerline of the semiconductor device as an axis, the working principle and the working state of the first electrode 510 and the second electrode 520 are the same, and are not described herein again. The graph (b) in fig. 2 shows the carrier distribution when a negative voltage is applied to the second electrode 520 and a positive voltage is applied to the first electrode 510. Similarly to the above process, when the forward bias voltage applied to the first electrode 510 reaches the knee voltage, the output current of the first electrode 510 tends to saturate to a certain fixed value. At this time, if the forward bias voltage on the first electrode 510 is continuously increased, the output current of the first electrode 510 is not changed due to the negative feedback, so that the constant current output is realized. Meanwhile, the semiconductor device can realize the function of bidirectionally outputting constant current in a certain voltage interval.
In one embodiment, the buffer layer 200 and the barrier layer 300 form a heterojunction. The heterojunction of a semiconductor is a special PN junction and is formed by sequentially depositing two or more different semiconductor material films on the same substrate, wherein the materials respectively have different energy band gaps. The response parameters of the current and the voltage of the diode can be changed by adjusting the thickness and the energy band gap of each material layer of the semiconductor in production. Semiconductor heterostructures have a significant impact on semiconductor technology and are a key component of high frequency transistors and optoelectronic devices. In the present embodiment, the buffer layer 200 and the barrier layer 300 form a heterojunction, and the response parameters of the current and voltage of the semiconductor device can be changed by adjusting the thicknesses and the energy band gaps of the buffer layer 200 and the barrier layer 300 when designing the performance of the semiconductor device.
In one embodiment, the material of the buffer layer includes GaN. Gallium nitride (GaN) is a wide bandgap semiconductor, has the advantages of high breakdown field strength, high electron mobility, high saturated electron drift velocity, large thermal conductivity, small dielectric constant, strong radiation resistance, good chemical stability and the like, and is an ideal semiconductor material in the application occasions of high voltage, high frequency, high temperature, high power density and the like. The GaN power electronic device has the outstanding advantages of wide band gap, high electronic saturation drift velocity, high thermal conductivity, high critical breakdown electric field and the like, greatly improves the voltage withstanding capacity, the working frequency and the current density of the GaN power electronic device, greatly reduces the conduction loss of the device, and enables the device to work under severe conditions of high power, high temperature and the like. The wide-bandgap semiconductor power electronic device has very wide military and civil values, such as the field of power electronic systems of military equipment such as tanks, naval vessels, airplanes and cannons, and the like, and civil power electronic equipment, household appliances, train traction equipment and high-voltage direct-current transmission equipment, and is also applied to systems such as PCs, hybrid vehicles, electric automobiles, solar power generation and the like. Among these new power electronic systems, GaN power electronic devices are one of the most core key technologies, which can greatly reduce the consumption of electrical energy, and thus are also known as "green energy" devices that drive "new energy revolution".
In one embodiment, the buffer layer may also be composed of a combination of an AlGaN layer, an AlN layer, and a GaN layer, wherein the uppermost layer is a GaN layer.
In one embodiment, the substrate is made of Si, SiC, sapphire or GaN.
In one embodiment, the material of the barrier layer 300 includes gallium aluminum nitride (AlGaN). Of course, the material of the barrier layer 300 is not limited to AlGaN, and may be other group III nitrides other than GaN.
Fig. 3 is a current-voltage characteristic diagram of a semiconductor device according to an embodiment of the present invention, and it can be seen from fig. 3 that the knee voltage of the semiconductor device is related to the thickness of the barrier layer 300, and the first and second grooves are formed on the barrier layer 300, and the thickness of the barrier layer 300 is related to the depths of the first and second grooves, so that the knee voltage of the semiconductor device is related to the depths of the first and second grooves. Meanwhile, when the forward bias voltage or the reverse bias voltage applied to the semiconductor device reaches the knee point voltage of the semiconductor device, the output current of the semiconductor device tends to be saturated, and no large amplitude change exists after the output current reaches a certain fixed value, so that constant current output is realized.
In one embodiment, the material of the passivation layer 600 includes SiN. Silicon nitride (SiN) is an important structural ceramic material. It is a superhard substance, has lubricity and abrasion resistance, is an atomic crystal, and resists oxidation at high temperature. It can resist cold and hot impact, and can be heated to above 1000 deg.C in air, and can be rapidly cooled and then rapidly heated, and can not be broken. Just because silicon nitride ceramics have such excellent characteristics, in the present embodiment, silicon nitride is used as the material of the passivation layer 600 of the semiconductor device to improve the quality of the semiconductor device and improve the heat resistance.
In one embodiment, the semiconductor device is a diode. In this embodiment, the semiconductor device is a two-terminal electronic device capable of bidirectionally outputting a constant current in a certain voltage interval, and the semiconductor device is a bidirectional constant current diode.
Fig. 4 is a flowchart of a method for manufacturing a semiconductor device according to an embodiment of the present invention, wherein the method for manufacturing a semiconductor device includes the following steps S100 to S600.
S100: a substrate is provided.
S200: a buffer layer is formed on the substrate.
S300: forming a barrier layer on one side of the buffer layer far away from the substrate; wherein a two-dimensional electron gas is formed between the buffer layer and the barrier layer.
S400: and partially etching two ends of one side of the barrier layer, which is far away from the buffer layer, so as to form a first contact area and a second contact area.
S500: forming a first electrode on the first contact region and a second electrode on the second contact region; the first electrode comprises a first ohmic contact electrode formed on the barrier layer and a first Schottky contact electrode shorted with the first ohmic contact electrode; the second electrode includes a second ohmic contact electrode formed on the barrier layer, and a second schottky contact electrode shorted to the second ohmic contact electrode.
S600: and forming a passivation layer between the first electrode and the second electrode on one side of the barrier layer far away from the buffer layer.
In fabricating the semiconductor device, a substrate 100 is first provided. The buffer layer 200 is formed on the substrate 100. The barrier layer 300 is formed on a side of the buffer layer 200 away from the substrate 100. Wherein a two-dimensional electron gas 400 is formed between the buffer layer 200 and the barrier layer 300. Both ends of the barrier layer 300 on the side away from the buffer layer 200 are partially etched to form a first groove and a second groove. Then, a first electrode 510 is formed on the first groove, and a second electrode 520 is formed on the second groove. Wherein the first electrode 510 includes a first ohmic contact electrode 511 formed on the barrier layer 300, and a first schottky contact electrode 512 shorted to the first ohmic contact electrode 511; the second electrode includes a second ohmic contact electrode 521 formed on the barrier layer 300, and a second schottky contact electrode 522 shorted to the second ohmic contact electrode 521. The first ohmic contact electrode 511 and the second ohmic contact electrode 521 may be formed at the same time, and the first schottky contact electrode 512 and the second schottky contact electrode 522 may be formed at the same time, but they are formed after the first ohmic contact electrode 511 and the second ohmic contact electrode 521. Finally, the passivation layer 600 is formed on the side of the barrier layer 300 away from the buffer layer 200, the passivation layer 600 being located between the first electrode 510 and the second electrode 520.
The two ends of the semiconductor device provided by the invention are provided with the first electrode 510 and the second electrode 520, and the first electrode 510 and the second electrode 520 are both mixed electrodes formed by short-circuiting an ohmic contact electrode and a Schottky contact electrode. The depletion region under the first schottky contact electrode at the first electrode 510 is gradually expanded as the voltage applied to the second electrode 520 is increased, and the two-dimensional electron gas channel of the depletion region under the first schottky contact electrode is even pinched off. Since the resistance of the expanded depletion region is large, the current is restricted from increasing further, and thus negative feedback is formed. When the voltage applied to the second electrode 520 reaches the knee voltage, the output current of the semiconductor device tends to be saturated and reaches a certain fixed value. Similarly, the depletion region under the second schottky contact electrode at the second electrode 520 gradually expands with increasing voltage applied to the first electrode 510 until the two-dimensional electron gas channel of the depletion region under the second schottky contact electrode is pinched off. When the voltage applied to the first electrode 510 reaches the knee voltage, the output current of the semiconductor device tends to be saturated and reaches a certain fixed value. The semiconductor device can output a constant current by applying a forward voltage to the first electrode 510 or applying a forward voltage to the second electrode 520 of the semiconductor device. Therefore, when the semiconductor device is applied to a circuit requiring bidirectional constant current, constant output currents in different directions can be obtained.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A semiconductor device, comprising:
a substrate;
a buffer layer disposed on the substrate;
a barrier layer disposed on the buffer layer on a side remote from the substrate; wherein, two-dimensional electron gas is formed at the junction of the buffer layer and the barrier layer;
the first electrode and the second electrode are arranged at two ends of the barrier layer far away from one side of the buffer layer; the first electrode comprises a first ohmic contact electrode formed on the barrier layer and a first Schottky contact electrode shorted with the first ohmic contact electrode; the second electrode comprises a second ohmic contact electrode formed on the barrier layer and a second Schottky contact electrode shorted with the second ohmic contact electrode;
the passivation layer is arranged on one side, far away from the buffer layer, of the barrier layer and is positioned between the first electrode and the second electrode.
2. The semiconductor device according to claim 1, wherein the barrier layer comprises a first groove and a second groove formed by etching on a side thereof away from the buffer layer; part of the first ohmic contact electrode is positioned in the first groove and is in contact with the bottom of the first groove to form a first ohmic contact structure, and part of the first Schottky contact electrode is positioned in the first groove and is in contact with the bottom of the first groove to form a first Schottky contact structure; and part of the second ohmic contact electrode is positioned in the second groove and is in contact with the bottom of the second groove to form a second ohmic contact structure, and part of the second Schottky contact electrode is positioned in the second groove and is in contact with the bottom of the second groove to form a second Schottky contact structure.
3. The semiconductor device of claim 2, wherein a knee voltage of the semiconductor device is related to a depth of the first and second recesses.
4. The semiconductor device according to claim 2, wherein the first schottky contact electrode and the second schottky contact electrode are symmetrically arranged with a vertical center line of the semiconductor device as an axis; the first ohmic contact electrode and the second ohmic contact electrode are also symmetrically distributed by taking a vertical middle line of the semiconductor device as an axis; the first and second Schottky contact electrodes are located between the first and second ohmic contact electrodes.
5. The semiconductor device according to claim 1, wherein the buffer layer and the barrier layer form a heterojunction.
6. The semiconductor device according to claim 1, wherein a material of the buffer layer comprises GaN.
7. The semiconductor device of claim 1, wherein the barrier layer comprises a material comprising AlGaN.
8. The semiconductor device according to claim 1, wherein a material of the passivation layer comprises SiN.
9. The semiconductor device according to any one of claims 1 to 8, wherein the semiconductor device is a bidirectional constant current diode.
10. A method for manufacturing a semiconductor device, comprising:
providing a substrate;
forming a buffer layer on the substrate;
forming a barrier layer on one side of the buffer layer far away from the substrate; wherein a two-dimensional electron gas is formed between the buffer layer and the barrier layer;
partially etching two ends of one side of the barrier layer, which is far away from the buffer layer, to form a first groove and a second groove;
forming a first electrode on the first groove and a second electrode on the second groove; the first electrode comprises a first ohmic contact electrode formed on the barrier layer and a first Schottky contact electrode shorted with the first ohmic contact electrode; the second electrode comprises a second ohmic contact electrode formed on the barrier layer and a second Schottky contact electrode shorted with the second ohmic contact electrode;
and forming a passivation layer between the first electrode and the second electrode on one side of the barrier layer far away from the buffer layer.
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| CN1918712A (en) * | 2004-02-12 | 2007-02-21 | 国际整流器公司 | Integrated iii-nitride power devices |
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| CN1918712A (en) * | 2004-02-12 | 2007-02-21 | 国际整流器公司 | Integrated iii-nitride power devices |
| CN104900643A (en) * | 2015-06-08 | 2015-09-09 | 西南交通大学 | Bidirectional triggering heterojunction type ESD protective device |
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Application publication date: 20201117 |