Cascade device

Abstract

The invention provides a cascade device, and relates to the technical field of semiconductors. The cascade device comprises a first low-voltage element, a high-voltage element and a current limiting element. The first low-voltage element comprises a first grid electrode, a first source electrode and a first drain electrode. The high-voltage element comprises a second grid electrode, a second source electrode and a second drain electrode; the second grid electrode is connected with the first source electrode. At least one end of the current limiting element is connected with the first drain, and one end is connected with the high-voltage element. The first grid electrode serves as a grid electrode of the cascade device, the first source electrode serves as a source electrode of the cascade device, and the second drain electrode serves as a drain electrode of the cascade device. When the cascade device is short-circuited, the partial voltage of the current limiting element can be increased, the voltage of the second grid is reduced, and the short-circuit current is limited, so that the short-circuit current bearing time of the whole cascade device is prolonged, and the anti-short-circuit performance is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a cascade device. Background Art

[0002] Cascode cascaded GaN (gallium nitride) devices are composed of low-voltage Si MOSFET (silicon-based metal oxide semiconductor field effect transistor) and high-voltage depletion-mode GaN HEMT (gallium nitride high electron mobility transistor) in a cascode manner. The drain of the high-voltage depletion-mode GaN HEMT is the drain of the cascade structure, and the gate of the low-voltage Si MOSFET is the gate of the cascade structure, ultimately achieving enhanced functions. Cascode cascaded GaN devices require GaN HEMTs and MOSFETs and other components to be packaged together in a certain connection method. GaN high electron mobility transistors are the main voltage-resistant devices, with high saturation current density and low on-resistance. GaN devices have poor short-circuit capabilities.

[0003] In many application scenarios of power electronics, short circuit conditions are inevitable. This requires power devices to have a certain ability to resist short circuits, that is, to withstand short circuit currents without damage within a certain period of time. This time usually needs to be more than 10μs. In GaN switching circuits, even the fastest short-circuit protection circuit has a reaction time of more than 2μs, and ordinary cascaded GaN HEMTs cannot meet this requirement. Summary of the invention

[0004] The purpose of the present invention includes providing a cascade device, which is beneficial to improving the short-circuit resistance of the cascade device.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] The present invention provides a cascade device, comprising:

[0007] A first low voltage element; the first low voltage element comprises a first gate, a first source and a first drain;

[0008] A high voltage element; the high voltage element comprises a second gate, a second source and a second drain; the second gate is connected to the first source;

[0009] A current limiting element; at least one end of the current limiting element is connected to the first drain electrode, and one end is connected to the high-voltage element;

[0010] The first gate serves as the gate of the cascade device, the first source serves as the source of the cascade device, and the second drain serves as the drain of the cascade device.

[0011] In an optional implementation manner, the current limiting element is a current limiting resistor manufactured using two-dimensional electron gas, TiN, polysilicon or metal technology.

[0012] In an optional implementation, the current limiting element includes a current limiting resistor, one end of the current limiting resistor is connected to the first drain, and the other end of the current limiting resistor is connected to the second source.

[0013] In an optional implementation, the current limiting element further includes a diode, and the diode and the current limiting resistor are connected in parallel.

[0014] In an optional embodiment, the current limiting element is a second low-voltage element, and the second low-voltage element includes a third source, a third drain and a third gate;

[0015] The third source is connected to the first drain, and the third drain is connected to the second source; or, the third source is connected to the second drain, and the third drain serves as the drain of the cascade device;

[0016] The third gate is floating or connected to the second gate.

[0017] In an optional embodiment, the current limiting element is a second low-voltage element, and the second low-voltage element includes a third source, a third drain and a third gate;

[0018] The third source is connected to the first drain, the third drain is connected to the second source, the third gate is connected to the third source, and the third gate is a non-ohmic contact gate.

[0019] In an optional embodiment, it further includes a capacitor and a resistor; one end of the capacitor is connected to the first source electrode, and the other end is connected to the first drain electrode;

[0020] One end of the resistor is connected to the first source, and the other end of the resistor is connected to the first drain.

[0021] In an optional embodiment, the current limiting element includes a substrate and a channel layer located on the substrate; the channel layer includes an active area and a passive area; the active area is provided with a two-dimensional electron gas;

[0022] A potential barrier layer and a first dielectric layer are provided on the side of the channel layer facing away from the substrate; a positive electrode and a negative electrode are provided in the passive region; both the positive electrode and the negative electrode penetrate the potential barrier layer and the first dielectric layer;

[0023] The positive electrode is connected to the second source electrode, and the negative electrode is connected to the first drain electrode.

[0024] In an optional embodiment, the positive electrode includes a plurality of first fingers connected in parallel, and the negative electrode includes a plurality of second fingers connected in parallel; the first fingers and the second fingers are staggered.

[0025] In an optional embodiment, the current limiting element further includes a base electrode, and the base electrode is arranged on a side of the first dielectric layer away from the barrier layer; the base electrode is a non-ohmic contact electrode.

[0026] In an optional embodiment, the base electrode includes a plurality of third fingers, each of the third fingers being disposed between adjacent first fingers and second fingers.

[0027] In an optional embodiment, the resistance value of the current limiting element is Among them, R S is the sheet resistance of the active region where the two-dimensional electron gas is located, L1 is the distance between the positive electrode and the negative electrode; W is the total width of the base electrode.

[0028] In an optional embodiment, the saturation current I of the current limiting element sat The calculation formula is:

[0029]

[0030] Among them I sat is the saturation current, μ 2DEG is the mobility of the two-dimensional electron gas, d is the thickness of the barrier layer, ε AlGaN is the dielectric constant of the barrier layer, V b is the voltage of the base electrode, V t is the cut-off voltage of the current limiting element; L2 is the length of the base electrode; W is the width of the base electrode of the current limiting element.

[0031] In an optional embodiment, the passive region is provided with a second source and a second drain; the second source and the second drain both penetrate the barrier layer and the first dielectric layer;

[0032] A second gate is provided on a side of the first dielectric layer away from the barrier layer, and the second gate is a non-ohmic contact electrode;

[0033] The positive electrode is connected to the second source electrode.

[0034] In an optional embodiment, the positive electrode and the second source electrode are the same electrode.

[0035] In an optional embodiment, a second dielectric layer is further provided on a side of the first dielectric layer away from the substrate.

[0036] In an optional embodiment, the substrate includes any one or more of sapphire, silicon, silicon carbide, diamond and gallium nitride.

[0037] The beneficial effects of the cascade device provided by the embodiment of the present invention include:

[0038] The cascade device provided in an embodiment of the present invention connects the first low-voltage element and the current limiting element. When a short circuit occurs, it is beneficial to increase the voltage division of the current limiting element and reduce the voltage of the second gate of the high-voltage element, thereby limiting the short-circuit current of the cascade device when a short circuit occurs, thereby extending the short-circuit current tolerance time of the entire cascade device and improving the short-circuit resistance performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A schematic diagram of the circuit structure of the cascade device provided in this embodiment;

[0041] Figure 2 A schematic diagram of the first structure of the current limiting resistor provided in this embodiment;

[0042] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure of AA;

[0043] Figure 4 A second structural schematic diagram of the current limiting resistor provided in this embodiment;

[0044] Figure 5 for Figure 4 Schematic diagram of the cross-sectional structure of the middle BB;

[0045] Figure 6 A schematic diagram of a structure in which a current limiting resistor provided in this embodiment is integrated into a high-voltage component GaN HEMT;

[0046] Figures 7 to 14 A schematic diagram of the circuit structure of various current limiting elements of the cascade device provided in this embodiment.

[0047] Icon: 100-cascade device; 110-first low-voltage element; 111-first gate; 112-first source; 113-first drain; 120-capacitor; 130-resistor; 140-high-voltage element; 141-second gate; 142-second source; 143-second drain; 150-current-limiting resistor; 151-positive electrode; 152-first interdigital finger; 153-negative electrode; 154-second interdigital finger; 155-base electrode; 156-third interdigital finger; 210-substrate; 220-buffer layer; 230-channel layer; 240-barrier layer; 250-first dielectric layer; 255-common electrode; 260-two-dimensional electron gas; 270-second dielectric layer; 160-second low-voltage element; 161-third source; 162-third drain; 163-third gate; 170-diode. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0051] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0052] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0053] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0054] Since the short-circuit current capability of GaN HEMT is directly related to its own saturation current density (saturation current / gate width), it is difficult for existing HEMT devices to have a low saturation current density while ensuring low on-resistance. Therefore, special technology is needed to reduce the saturation current density of HEMT devices. Some existing technologies, such as SCCL and SchottkySource, choose to directly add current limiting processes between the HEMT gate or gate source. These current limiting processes usually involve the gate dielectric and gate electrode of the HEMT. While reducing the saturation current density, they also increase the conduction loss of the device, affecting the device performance. Moreover, adding these current limiting processes on the basis of the conventional process of HEMT devices increases the complexity of the process, places high demands on process capabilities, and limits technical means.

[0055] In order to overcome at least one defect in the prior art, the present application proposes a cascade device with a simple process preparation method, which does not require adding additional complex processes to the basic process, does not affect the conduction performance of the device, and can also improve the short-circuit resistance of the cascade device.

[0056] Please combine Figure 1 The cascade device 100 provided in the embodiment of the present invention includes a first low-voltage element 110, a capacitor 120, a resistor 130, a high-voltage element 140 and a current limiting element. The first low-voltage element 110 includes a first gate 111, a first source 112 and a first drain 113. One end of the capacitor 120 is connected to the first source 112, and the other end is connected to the first drain 113. One end of the resistor 130 is connected to the first source 112, and the other end is connected to the first drain 113. The high-voltage element 140 includes a second gate 141, a second source 142 and a second drain 143; the second gate 141 is connected to the first source 112. The current limiting element has at least two connection ends, at least one end is connected to the first drain 113, and one end is connected to the high-voltage element 140. The first gate 111 serves as the gate of the cascade device 100, the first source 112 serves as the source of the cascade device 100, and the second drain 143 serves as the drain of the cascade device 100. In the cascade device 100, the first low-voltage element 110 and the current-limiting element are connected, which is beneficial to increase the voltage division of the current-limiting element and reduce the voltage of the second gate 141 of the high-voltage element 140 when a short circuit occurs, thereby limiting the short-circuit current of the cascade device 100 when a short circuit occurs, thereby extending the short-circuit current tolerance time of the entire cascade device 100 and improving the short-circuit resistance performance.

[0057] In the figure, Gate represents the gate of the entire cascade device 100 , Source represents the source of the entire cascade device 100 , and Drain represents the drain of the entire cascade device 100 .

[0058] The first low-voltage element 110 may be a low-voltage Si MOSFET, i.e., a low-voltage silicon-based metal oxide semiconductor field effect transistor. The high-voltage element 140 may be a high-voltage depletion-mode gallium nitride high electron mobility transistor, i.e., a GaN HEMT. The current-limiting element includes, but is not limited to, a current-limiting resistor 150 made of two-dimensional electron gas 260 (2DEG), TiN (titanium nitride), polysilicon or metal technology.

[0059] Optionally, the current limiting element includes a current limiting resistor 150. One end of the current limiting resistor 150 is connected to the first drain 113, and the other end is connected to the second source 142. In this embodiment, the current limiting element uses a resistor made of temperature-sensitive 2DEG, which has a simpler process and has less impact on the performance of the cascade device 100. It can be understood that the current limiting resistor 150 is sensitive to temperature, and the resistance value increases sharply with increasing temperature. After the current limiting resistor 150 is connected in series with the GaN HEMT, when the cascade device 100 is short-circuited, the second drain 143 of the high-voltage element 140 is a high voltage, and the voltage drop is mainly on the high-voltage element 140. The first low-voltage element 110 operates in the linear region, the high-voltage element 140 operates in the saturation region, and the voltage across the current limiting resistor 150 is proportional to the current passing through it. Under short-circuit conditions, the current passing through the current limiting resistor 150 is greatly increased, the voltage at both ends is significantly increased, the voltage difference between the second gate 141 and the second source 142 of the high-voltage element 140 becomes larger, the saturation current density decreases, and the short-circuit capability of the entire cascade device 100 is improved.

[0060] Optionally, if the current limiting resistor 150 is distributed at the center of the heat source or where the heat is obviously concentrated during the overall layout, under the short-circuit condition, the temperature of the current limiting resistor 150 rises sharply, the resistance value increases rapidly, the voltage division is greater, and the current limiting effect is more obvious.

[0061] Optionally, the saturation current density of the current limiting resistor 150 is much lower than that of the high voltage component 140 and the first low voltage component 110. When the cascade device 100 is short-circuited, the current limiting resistor 150 operates in the saturation region, and the current of the high voltage component 140 is limited by the current limiting resistor 150, and does not reach saturation, and is not easily damaged, and the short-circuit capability of the entire cascade device 100 is improved.

[0062] Please combine Figure 2 and Figure 3Optionally, the current limiting element includes a substrate 210, a buffer layer 220, a channel layer 230, a barrier layer 240 and a first dielectric layer 250 stacked in sequence from bottom to top. The channel layer 230 includes an active region and an inactive region; the active region is provided with a two-dimensional electron gas 260. The inactive region is provided with a positive electrode 151 and a negative electrode 153; the positive electrode 151 and the negative electrode 153 both penetrate the barrier layer 240 and the first dielectric layer 250. The positive electrode 151 is connected to the second source 142, and the negative electrode 153 is connected to the first drain 113. The positive electrode 151 and the negative electrode 153 are ohmic contact electrodes, respectively.

[0063] Optionally, the positive electrode 151 includes a plurality of first interdigits 152 connected in parallel, and the negative electrode 153 includes a plurality of second interdigits 154 connected in parallel; the first interdigits 152 and the second interdigits 154 are arranged in a staggered manner. It should be understood that the first interdigit 152 is inserted between two adjacent second interdigits 154, and the second interdigit 154 is inserted between two adjacent first interdigits 152, and the two are inserted into each other but not in contact.

[0064] Optionally, the current limiting element further includes a base electrode 155 , which is disposed on a side of the first dielectric layer 250 away from the barrier layer 240 ; the base electrode 155 is a non-ohmic contact electrode.

[0065] Optionally, the base electrode 155 includes a plurality of third fingers 156 , each of which is disposed between adjacent first fingers 152 and second fingers 154 .

[0066] Optional, current limiting element resistor value Among them, R S is the sheet resistance of the active region where the two-dimensional electron gas 260 is located, L1 is the distance between the positive electrode 151 and the negative electrode 153; W is the total width of the base electrode 155, that is, Figure 3 The total length of the base electrode 155 along the serpentine is shown in FIG.

[0067] Optional, current limiting element saturation current I sat The calculation formula is:

[0068]

[0069] Among them I sat is the saturation current, μ 2DEG is the mobility of the two-dimensional electron gas 260, d is the thickness of the barrier layer 240, ε AlGaN is the dielectric constant of the barrier layer 240, V b is the voltage of the base electrode 155, V t is the cut-off voltage of the current limiting element; L2 is the length of the base electrode 155; and W is the width of the base electrode 155 of the current limiting element.

[0070] Figure 2 L2 shown in FIG. 1 is the length of the base electrode 155 . L2 can be used to adjust the saturation current of the current limiting resistor 150 . The longer L2 is, the lower the saturation current is.

[0071] In this embodiment, the substrate 210 includes any one or any combination of sapphire, silicon, silicon carbide, diamond and gallium nitride, and sapphire can be selected. A buffer layer 220 is also provided between the substrate 210 and the channel layer 230. The buffer layer 220 is a combination of any one or more of an aluminum nitride layer, a gallium nitride layer, an aluminum gallium nitride layer, etc., and can be selected as a gallium nitride layer. The material of the channel layer 230 is, for example, at least one of gallium nitride, AlN, and InN, and can be selected as gallium nitride. The material of the barrier layer 240 is, for example, at least one of aluminum gallium nitride, InGaN and AlInGaN, and can be selected as aluminum gallium nitride. The material of the first dielectric layer 250 includes, but is not limited to, at least one of silicon nitride, aluminum oxide and silicon oxide.

[0072] It is easy to understand that the interface between the channel layer 230 and the barrier layer 240 forms a heterojunction, in which a two-dimensional carrier gas, such as a two-dimensional electron gas 260, is provided. In this embodiment, the current limiting resistor 150 adopts 2DEG, which has a shorter response time and is more suitable for application in the GaN cascade device 100. And the appropriate resistance value can be adjusted by adjusting the 2DEG concentration, mobility, the length L1 between the two electrodes of the current limiting resistor 150, and the length L2 of the base electrode 155 of the current limiting resistor 150.

[0073] Combination Figure 4 and Figure 5 In some embodiments, the base electrode 155 may be omitted. That is, the current limiting resistor 150 includes a positive electrode 151 and a negative electrode 153. The positive electrode 151 and the negative electrode 153 are interdigitated and inserted into each other.

[0074] Optionally, the current limiting resistor 150 can be an independent device or integrated with the GaN HEMT. If the two are integrated together, the two can share the same substrate 210, buffer layer 220, channel layer 230, barrier layer 240 and first dielectric layer 250, etc. The preparation processes of the two do not conflict and can be completed on the same production line.

[0075] Combination Figure 6Optionally, a second source 142 and a second drain 143 of the GaN HEMT are also provided in the passive area of ​​the channel layer 230; the second source 142 and the second drain 143 both penetrate the barrier layer 240 and the first dielectric layer 250. The second source 142 and the second drain 143 are both ohmic contact electrodes. A second gate 141 is provided on the side of the first dielectric layer 250 away from the barrier layer 240, and the second gate 141 is a non-ohmic contact electrode. Among them, the positive electrode 151 and the second source 142 are electrically connected. It can be understood that in order to improve the integration, the positive electrode 151 and the second source 142 are the same electrode, that is, the common electrode 255. In this way, the preparation of one electrode can be reduced, the number of electrodes can be reduced, the preparation efficiency can be improved, and the electrical connection is more reliable. Of course, in some other embodiments, the positive electrode 151 of the current limiting resistor 150 and the second source 142 of the high voltage element 140 (GaN HEMT) can be prepared separately, and then the two can be electrically connected by wire bonding or other methods, which is not specifically limited here.

[0076] Optionally, a second dielectric layer 270 is further provided on the side of the first dielectric layer 250 away from the substrate 210, and the second source 142, the second drain 143 and the second gate 141 are exposed from the surface of the second dielectric layer 270. The material of the second dielectric layer 270 is the same or similar to that of the first dielectric layer 250. Optionally, a top-layer interconnection structure may be selectively designed on the surface of the second dielectric layer 270. Of course, the top-layer interconnection structure may also be omitted.

[0077] The preparation method of the current limiting resistor 150 is as follows:

[0078] Step S100: providing a wafer with a two-dimensional electron gas 260. Optionally, the wafer includes a substrate 210 and an epitaxial structure on the substrate 210. Specifically, a buffer layer 220 is formed on the substrate 210, a channel layer 230 is formed on the buffer layer 220, and a barrier layer 240 is formed on the channel layer 230. A two-dimensional electron gas 260 is formed between the interface of the channel layer 230 and the barrier layer 240.

[0079] Step S200: isolating active regions and passive regions on a wafer. Optionally, according to the designed positions of the ohmic contact electrodes, photolithography technology is used to etch and isolate active regions and passive regions on the wafer.

[0080] Step S300: removing the two-dimensional electron gas 260 in the inactive region. The two-dimensional electron gas 260 in the inactive region may be removed by ion implantation or etching.

[0081] Step S400: using photolithography technology to form an ohmic contact region in the passive region, and using photolithography technology to form a non-ohmic contact region in the active region.

[0082] Step S500: metallizing the ohmic contact region to form ohmic contact electrodes, namely, the positive electrode 151 and the negative electrode 153. Optionally, the ohmic contact electrodes may be formed by electroplating metal, evaporating metal, or sputtering metal after photolithography. Optionally, after forming the ohmic contact electrodes, the ohmic contact electrodes are annealed by thermal annealing technology to reduce contact resistance and improve structural reliability.

[0083] Step S600: metallizing the non-ohmic contact region to form a non-ohmic contact electrode, that is, forming a base electrode 155. Optionally, a first dielectric layer 250 is formed on the side of the barrier layer 240 away from the substrate 210, and a non-ohmic contact electrode is formed on the first dielectric layer 250. The base electrode 155 can be formed by electroplating metal, evaporating metal, or sputtering metal after photolithography.

[0084] It can be understood that the above process is the main process steps for separately preparing the current limiting resistor 150. That is, a separate current limiting resistor 150 can be formed through the above process, and the current limiting resistor 150 is an independent component.

[0085] Of course, the current limiting resistor 150 can also be integrated with the high voltage component 140. For example, when preparing the high voltage component 140 HEMT, the current limiting resistor 150 is integrated into the high voltage component 140. In this way, the high voltage component 140 and the current limiting resistor 150 are an integral device. The main process steps are as follows:

[0086] Steps S100 to S400 are as above, and since the current limiting resistor 150 and the high voltage element 140 are integrated together, the distribution positions of the active area and the passive area are adjusted accordingly, and the formed ohmic contact area and the non-ohmic contact area are also adjusted accordingly.

[0087] The ohmic contact region is metallized to form an ohmic contact electrode, namely, a positive electrode 151, a negative electrode 153, a second drain electrode 143, and a second source electrode 142. The non-ohmic contact region is metallized to form a non-ohmic contact electrode, namely, a base electrode 155 and a second gate electrode 141. A second dielectric layer 270 is formed on the side of the first dielectric layer 250 away from the substrate 210.

[0088] Optionally, the positive electrode 151 and the second source electrode 142 are designed to be the same electrode. That is, a common electrode 255 is formed by metallization in the ohmic contact area, and the common electrode 255 serves as both the positive electrode 151 of the current limiting resistor 150 and the second source electrode 142 of the high-voltage element 140. In this way, the number of electrodes produced is reduced, and the reliability of the electrical connection between the second source electrode 142 and the positive electrode 151 can be ensured.

[0089] It can be seen that when the preparation process of the current limiting resistor 150 is adopted to prepare an independent device of the current limiting resistor 150, the process flow is simple, there are no too many complicated processes, and the performance of the overall cascade device 100 will not be reduced. In addition, the preparation process of the current limiting resistor 150 does not conflict with the preparation process of the high-voltage component 140 HEMT, and can be integrated together when preparing the high-voltage component 140 (GaN HEMT), without the need for additional complicated processes, with high preparation efficiency and good operability. Compared with the existing current limiting process of reducing the saturation current density or adding an additional Schottky source electrode by injection, etching isolation and other technologies inside the HEMT, the solution of this embodiment will not damage the second gate 141, nor will it increase the on-resistance of the GaN HEMT. And the process is simpler, and the requirements for the process level are relatively low.

[0090] In some other embodiments, the current limiting element may also be other structures, combined with Figure 7 The current limiting element further includes a current limiting resistor 150 and a diode 170 , and the diode 170 and the current limiting resistor 150 are connected in parallel.

[0091] Combination Figure 8 , the current limiting element adopts the second low voltage element 160, and the second low voltage element 160 includes but is not limited to the use of Lv-High electron mobility transistor, low voltage high electron mobility transistor, referred to as low voltage HEMT. The second low voltage element 160 replaces the current limiting resistor 150. The second low voltage element 160 includes a third source 161, a third drain 162 and a third gate 163. The third source 161 is connected to the first drain 113, the third drain 162 is connected to the second source 142; the third gate 163 is floating.

[0092] Combination Fig. 9 The current limiting element adopts the second low voltage element 160. The third source 161 of the second low voltage element 160 is connected to the second drain 143, and the third drain 162 serves as the drain of the cascade device 100; the third gate 163 is connected to the second gate 141. The second source 142 is connected to the first drain 113.

[0093] Combination Fig.10 The current limiting element adopts the second low voltage element 160. The third source 161 of the second low voltage element 160 is connected to the second drain 143, and the third drain 162 serves as the drain of the cascade device 100; the third gate 163 is floating.

[0094] Combination Fig.11The current limiting element is a second low voltage element 160. The third source 161 of the second low voltage element 160 is connected to the first drain 113, the third drain 162 is connected to the second source 142, the third gate 163 is connected to the third source 161, and the third gate 163 is a non-ohmic contact gate.

[0095] Combination Fig.12 The current limiting element is a second low voltage element 160 . The third source 161 of the second low voltage element 160 is connected to the first drain 113 , the third drain 162 is connected to the second source 142 , and the third gate 163 is connected to the second gate 141 .

[0096] Combination Fig.13 The current limiting element is a current limiting resistor 150. One end of the current limiting resistor 150 is connected to the first drain 113, and the other end is connected to one end of the capacitor 120 connected to the first drain 113.

[0097] Combination Fig.14 The current limiting element is a current limiting resistor 150. One end of the current limiting resistor 150 is connected to one end of the capacitor 120 connected to the first drain 113, and the other end is connected to one end of the resistor 130 connected to the first drain 113.

[0098] In summary, the cascade device 100 provided in the embodiment of the present invention has the following beneficial effects, including:

[0099] The cascade device 100 provided in the embodiment of the present invention connects the first low-voltage element 110 and the current limiting element. When short-circuited, the current passing through the current limiting element increases, which is conducive to increasing the voltage division at both ends of the current limiting element, reducing the voltage of the second gate 141 of the high-voltage element 140, so that the voltage difference between the second gate 141 and the second source 142 increases, and the saturation current density during short circuit is reduced. At the same time, the current limiting element also has the function of limiting the saturation current, thereby limiting the short-circuit current of the cascade device 100 when short-circuited, thereby extending the short-circuit current bearing time of the entire cascade device 100 and improving the short-circuit resistance. The current limiting element adopts the current limiting resistor 150 prepared by 2DEG, which has a shorter response time and is more suitable for application in the GaN cascade device 100. And the appropriate resistance value can be adjusted by adjusting the concentration, mobility, length L1 between the two electrodes (positive electrode 151 and negative electrode 153) and length L2 of the base electrode 155 of 2DEG.

[0100] Furthermore, the manufacturing process of the current limiting element does not conflict with the manufacturing process of the existing high-voltage element 140 HEMT, and does not require additional complex processes. It can be manufactured separately or integrated into one when the high-voltage element 140 is manufactured. The process is simple, efficient, and has relatively low requirements on the process level. It will not increase the on-resistance of the GaN HEMT, nor will it damage the second gate 141. The manufactured cascade device 100 has good reliability and high short-circuit resistance.

[0101] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A cascade device, characterized in that: include: A first low-voltage element (110); the first low-voltage element (110) comprises a first gate (111), a first source (112) and a first drain (113); A high-voltage element (140); the high-voltage element (140) comprises a second gate (141), a second source (142) and a second drain (143); the second gate (141) is connected to the first source (112); A current limiting element; the current limiting element comprises at least two connection ends, at least one end is connected to the first drain (113), and one end is connected to the high-voltage element (140); The first gate (111) serves as the gate of the cascade device, the first source (112) serves as the source of the cascade device, and the second drain (143) serves as the drain of the cascade device.

2. The cascade device according to claim 1, characterized in that: The current limiting element is a current limiting resistor (150) manufactured using two-dimensional electron gas (260), TiN, polysilicon or metal technology; one end of the current limiting resistor (150) is connected to the first drain (113), and the other end is connected to the second source (142).

3. The cascade device according to claim 2, characterized in that: The current limiting element further comprises a diode (170), and the diode (170) and the current limiting resistor (150) are connected in parallel.

4. The cascade device according to claim 1, characterized in that: The current limiting element adopts a second low-voltage element (160), and the second low-voltage element (160) comprises a third source (161), a third drain (162) and a third gate (163); The third source (161) is connected to the first drain (113), and the third drain (162) is connected to the second source (142); or, the third source (161) is connected to the second drain (143), and the third drain (162) serves as the drain of the cascade device; The third gate (163) is floating or connected to the second gate (141).

5. The cascade device according to claim 1, characterized in that: The current limiting element adopts a second low-voltage element (160), and the second low-voltage element (160) comprises a third source (161), a third drain (162) and a third gate (163); The third source (161) is connected to the first drain (113), the third drain (162) is connected to the second source (142), the third gate (163) is connected to the third source (161), and the third gate (163) is a non-ohmic contact gate.

6. The cascade device according to claim 1, characterized in that: It also includes a capacitor (120) and a resistor (130); one end of the capacitor (120) is connected to the first source (112), and the other end is connected to the first drain (113); One end of the resistor (130) is connected to the first source (112), and the other end is connected to the first drain (113).

7. The cascade device according to any one of claims 1 to 6, characterized in that: The current limiting element comprises a substrate (210) and a channel layer (230) located on the substrate (210); the channel layer (230) comprises an active region and an inactive region; the active region is provided with a two-dimensional electron gas (260); A barrier layer (240) and a first dielectric layer (250) are provided on the side of the channel layer (230) facing away from the substrate (210); a positive electrode (151) and a negative electrode (153) are provided in the passive region; the positive electrode (151) and the negative electrode (153) both penetrate the barrier layer (240) and the first dielectric layer (250); The positive electrode (151) is connected to the second source electrode (142), and the negative electrode (153) is connected to the first drain electrode (113).

8. The cascade device according to claim 7, characterized in that: The current limiting element further comprises a base electrode (155), wherein the base electrode (155) is arranged on a side of the first dielectric layer (250) away from the barrier layer (240); the base electrode (155) is a non-ohmic contact electrode.

9. The cascade device according to claim 7, characterized in that: The passive region is provided with a second source electrode (142) and a second drain electrode (143); the second source electrode (142) and the second drain electrode (143) both penetrate the barrier layer (240) and the first dielectric layer (250); A second gate (141) is provided on a side of the first dielectric layer (250) away from the barrier layer (240), and the second gate (141) is a non-ohmic contact electrode; The positive electrode (151) and the second source electrode (142) are connected.

10. The cascade device according to claim 9, characterized in that: The positive electrode (151) and the second source electrode (142) are the same electrode.

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