JP2016119463A5 - - Google Patents

Description

High electron mobility transistor

Cross-reference to related applications Under Article 119 of the U.S. Patent Act, this application claims the priority of U.S. Provisional Patent Application No. 61 / 921,140 filed on December 27, 2013. The entire contents are incorporated herein by reference.

Technical Fields The present specification relates to high electron mobility transistors, and more particularly to the design of field plates and other components of high electron mobility transistors.

A high electron mobility transistor (HEMT), also called a heterostructured field effect transistor (HFET), is a field effect transistor containing a heterojunction that functions as a transistor channel. In HEMT, the conduction of "two-dimensional electron gas" in the heterojunction channel is regulated by the gate.

Despite the invention in the late 1970s and the commercial success of HEMTs in applications such as millimeter-wave band switches, some HEMTs (eg, gallium nitride HEMTs for power electronics) are commercially available. Development is slower than expected.

Field plates are conductive elements commonly used to alter the appearance of electric fields in semiconductor devices. Generally, the field plate is designed to reduce the peak value of the electric field in the semiconductor device, and as a result, improve the breakdown voltage and the life of the device including the field plate.

In HEMTs (eg, gallium nitride HEMTs), field plates are also believed to reduce parasitic effects commonly referred to as "dc-rf dispersion" or "drain current collapse". During operation at relatively high frequencies (eg, radio frequencies), devices subject to this parasitic effect reach a drain current level that is less than the drain current level reached during direct current (dc) operation. The parasitic effect is thought to be due to the relatively slow response time of the interface state.

Experimental studies have been conducted on the length of field plates in HEMTs. For example, researchers explain that in some HEMT devices, the breakdown voltage approaches (ie, "saturates") the breakdown voltage after the gate connection field plate extends a certain distance towards the drain. doing. Moreover, the extension of the gate connection field plate beyond the saturation length towards the drain improves little or no breakdown voltage. It is recommended that the extension of the gate connection field plate towards the drain should be limited once the saturation length is reached, as the input capacitance of the gate increases as the gate connection field plate approaches the drain. Has been done.

High electron mobility transistors, including field plates, are described. In the first embodiment, the HEMT is a first semiconductor material, a second semiconductor material, a source electrode, and a drain electrode arranged so as to form a heterojunction at a position where a two-dimensional electron gas is generated. And a gate electrode, two-dimensional electron gas is generated in the heterojunction, the gate electrode is arranged so as to adjust the conduction in the heterojunction between the source electrode and the drain electrode, and the gate is on the drain side. The end portion, the gate connection field plate disposed above the drain side end portion of the gate electrode and extending laterally toward the drain, and the gate connection field plate disposed above the drain side end portion of the gate connection field plate. It has a second field plate that extends laterally towards the drain.

In the second embodiment, the HEMT is a first semiconductor material, a second semiconductor material, a source electrode, and a drain electrode arranged so as to form a heterojunction at a position where a two-dimensional electron gas is generated. The gate electrode is arranged so as to adjust the conduction in the heterojunction between the source electrode and the drain electrode, and the gate is arranged at the drain side end portion and the drain side end portion of the gate electrode. A gate connection field plate arranged above the drain and extending laterally toward the drain, and a second electrode connecting field plate arranged above the drain side end of the gate connection field plate and extending laterally toward the drain. It has 2 field plates and. In the off state, the first electric field in the heterojunction extends from the drain side end of the gate connection field plate toward the drain side, and the second electric field in the heterojunction is the drain side end of the second field plate. The source-drain potential difference that extends from the portion to the source side and exceeds the source-drain potential difference in which the charge carrier is depleted from a part of the heterojunction near the drain side end of the second field plate. Only in, the first electric field first overlaps the second electric field.

In the third embodiment, in the semiconductor device, the substrate, the first active layer disposed on the substrate, and the transverse conductive channel are generated between the first active layer and the second active layer. A second active layer disposed on the first active layer, source and drain electrodes, a first passivation layer disposed above the second active layer, and a first passivation layer disposed above the first active layer. A gate electrode, a second passivation layer disposed above the gate electrode, a gate field plate extending a first distance beyond the end of the gate electrode closest to the drain electrode, and above the first metal pattern. A third passivation layer provided and a second extending over a second distance beyond the end of the gate field plate, which is electrically connected to one of the source and gate electrodes and is closest to the drain electrode. Includes 2 field plates. The end of the second field plate is separated by a third distance from the first extending portion of the drain electrode adjacent to the second field plate. For a first drain bias greater than the absolute value of the available gate swing amplitude above the smaller threshold, the electric field at the gate end when part of the laterally conductive channel below the gate electrode is pinched off. The first distance is selected so that the gradual increase peaks.

Each of the first, second, and third embodiments may include one or more of the following features:

In the off state and at source-drain potential differences above the absolute value of the gateswing amplitude, the charge carriers are depleted from some of the heterojunctions near the drain side end of the gate connection field plate, depleting the charge carriers. The conversion is effective in saturating the lateral electric field in the heterojunction near the drain side end of the gate electrode. Charge carriers, at 2-5 times the source-drain potential difference of the absolute value of the gate swing amplitude can depleted. For example, charge carriers, at 3-4 times the source-drain potential difference of the absolute value of the gate swing amplitude, depleted.

The charge carrier is the second field plate in the off state and at a potential difference between the source and drain that exceeds the potential difference that depletes the charge carrier from that part of the heterojunction near the drain side end of the gate connection field plate. Can be depleted from some of the heterojunctions near the drain side end of the charge carrier, which is effective in saturating the lateral electric field in the heterojunction near the drain side end of the gate connection field plate. Is the target. For example, the potential difference at which the charge carrier is depleted from a part of the heterojunction near the drain side end of the second field plate is the charge carrier from part of the heterojunction near the drain side end of the gate connection field plate. Is 3 to 5 times the potential difference that depletes. For example, in the off state, the first electric field in the heterojunction extends from the drain side end of the gate connection field plate toward the drain side, and the second electric field in the heterojunction is the drain of the second field plate. The source, which extends from the side end towards the source side , and where the first electric field first depletes the charge carrier from a portion of the heterojunction near the drain side end of the second field plate. It overlaps with the second electric field only when the potential difference between the source and drain exceeds the potential difference between drains.

The HEMT or semiconductor device may include a third field plate disposed above the drain side end of the second field plate and extending laterally towards the drain. Hetero in the vicinity of the drain, with a potential difference between the source and drain that exceeds the potential difference between the source and drain in which the charge carrier is depleted from a part of the heterojunction in the off state and near the drain side end of the second field plate. Part of the junction is depleted due to the longitudinal voltage difference between the heterojunction and the third field plate. The third field plate can be a source connection field plate.

In a HEMT or semiconductor device in the off state, the first electric field in the heterojunction can spread from the drain side end of the gate connection field plate towards the drain side, and the second electric field in the heterojunction is the second. The first electric field extends from the drain side end of the field plate to the source side , and the charge carrier is first depleted from a part of the heterojunction near the drain side end of the second field plate. It overlaps with the second electric field only when the potential difference between the source and drain exceeds the potential difference between the source and drain. The first electric field is first generated only at a source-drain potential difference that exceeds the source-drain potential difference in which the charge carrier is depleted from a portion of the heterojunction near the drain side end of the second field plate. It can overlap with the electric field.

The HEMT or semiconductor device may include one or more insulating material layers above the first and second semiconductor materials, and certain sheet carrier densities may occur in heterojunctions. After reaching steady state after long-term operation with certain operating parameters, the number of charge defects per unit area in the insulating material layer is less than the sheet carrier density. For example, the number of charge defects per unit area in the insulating material layer can be less than 10% of the sheet carrier density.

The HEMT or semiconductor device may include GaN and AlGaN. The HEMT or semiconductor device may include an aluminum silicon nitride layer that insulates the gate electrode from the second semiconductor material.

In a HEMT or semiconductor device that is off, and at a source-drain potential difference that exceeds the source-drain potential difference that depletes the charge carrier from part of the heterojunction near the drain side end of the second field plate. , A portion of the heterojunction in the vicinity of the drain is depleted due to the longitudinal voltage difference between the heterojunction and the third field plate.

In a HEMT or semiconductor device that is in the off state, the source and drain electrodes may be disposed above the second active layer. The gate field plate may be defined by a first metal pattern disposed on the second passivation layer, the first metal pattern extending laterally above the entire gate electrode. The second field plate can be a source field plate defined by a second metal pattern disposed on the third passivation layer. The second metal pattern can be electrically connected to the source electrode and extends laterally above the entire first metal pattern and is the end of the first metal pattern closest to the drain electrode. It extends further beyond the second distance. The end of the second metal pattern may be separated by a third distance from the first extension of the drain electrode adjacent to the second metal pattern.

The HEMT or semiconductor device may include a fourth passivation layer disposed above the second metal pattern, which is a shield wrap defined by a third metal pattern disposed on the fourth passivation layer. The third metal pattern can be electrically connected to the source electrode, and the third metal pattern ends at a third distance from the second extension of the drain electrode adjacent to the third metal pattern. Can extend laterally above most of the laterally conductive channels so as to have. The end-to-end distance between the third metal pattern and the second extension of the drain electrode can be 2-6 micrometers. The thickness of the fourth passivation layer can be 0.5-2 micrometers. The first drain bias is obtained at about 2-5 times greater than the absolute value of the available gate swing amplitude above the threshold. The second distance is for a second drain bias that is greater than the peaking bias of the gate end electric field provided by the gate field plate when part of the laterally conductive channel below the gate electrode is in a pinch-off state. It may be sufficient to provide a plateau to the end electric field of the field plate. For example, the second drain bias can be about 2.5 to 10 times greater than the first drain bias. The second distance is at least the lateral depletion extension below the second metal pattern before the laterally conductive channel is vertically pinched off below the end of the second metal pattern closest to the drain end. It can be long enough so that the portion never reaches the end of the second metal pattern. The first distance can be 1.5-3.5 micrometers. The second distance can be 2.5 to 7.5 micrometers and the third distance can be 2 to 6 micrometers. The end-to-end distance between the gate electrode and the drain electrode can be 8 to 26 micrometers. The thickness of the third passivation layer can be 0.35-0.75 micrometers.

FIG. 1 is a schematic cross-sectional view of the transverse channel HEMT. FIG. 2 is a schematic cross-sectional view of the transverse channel HEMT. FIG. 3 is a schematic cross-sectional view of the transverse channel HEMT. 4A and 4B are graphs schematically showing the voltage and electric field at the heterojunction between the source and drain of the HEMTs of some embodiments that are off, respectively. 5A and 5B are graphs schematically representing the voltage and electric field at the heterojunction between the source and drain of the HEMTs of some embodiments that are on, respectively. 6A, 6B are heterogeneous between the source and drain of some embodiments in the off state for fixed source and gate potentials, respectively, for a variety of different and distinct drain potentials. It is a graph which shows roughly the voltage and electric potential at a junction. Same as above FIG. 7 shows the electric field at the heterojunction between the source and drain of some embodiments of HEMT in the off state for a fixed source and gate potential, with a variety of different and distinct drain potentials. It is a graph which shows roughly. FIG. 8 shows the electric field at the heterojunction between the source and drain of some embodiments of HEMT in the off state for a fixed source and gate potential, with a variety of different and distinct drain potentials. It is a graph which shows roughly. FIG. 9 schematically illustrates the electric field at the heterojunction of HEMTs in some embodiments that are off, in the case of fixed source and gate potentials, with a variety of different and distinct drain potentials. It is a graph.

FIG. 1 is a schematic cross-sectional view of the lateral channel HEMT100. The HEMT 100 includes a first semiconductor material 105 and a second semiconductor material 110 that are in contact with each other to form a heterojunction 115. Due to the material properties of the semiconductor materials 105 and 110, the two-dimensional electron gas 120 is generated at the heterojunction 115. The HEMT 100 further includes a source electrode 125, a drain electrode 130, and a gate electrode 135. The selective bias application of the gate electrode 135 adjusts the conductivity between the source electrode 125 and the drain electrode 130.

HEMT100 further includes a field plate structure 135 layered in the longitudinal direction. In the illustrated embodiment, the field plate structure 135 is a dual field plate structure that includes a gate connection field plate 140 and a source connection field plate 145. The gate connection field plate 140 is electrically connected to the gate electrode 135. The source connection field plate 145 is electrically connected to the source electrode 125.

In the illustrated embodiment, the gate electrode 135, the gate connection field plate 140, and the source connection field plate 145 each have a substantially rectangular cross section. The gate electrode 135 includes a bottom drain side end 150. The drain side end portion 150 has a lateral distance d0 from the side portion of the source electrode 125 toward the drain electrode 130, and is arranged at a longitudinal distance d5 above the second semiconductor material 110. The drain side end portion 150 is vertically separated from the second semiconductor material 110 by the first insulating material layer 155. The gate connection field plate 140 includes a bottom drain side end 160. The drain side end portion 160 has a lateral distance d0 + d1 from the side portion of the source electrode 125 toward the drain electrode 130, and is arranged at a vertical distance d5 + d6 above the second semiconductor material 110. The drain side end portion 160 is vertically separated from the second semiconductor material 110 by both the first insulating material layer 155 and the second insulating material layer 165. The source connection field plate 145 includes a bottom drain side end 170. The drain side end portion 170 has a lateral distance d0 + d1 + d3 from the side portion of the source electrode 125 toward the drain electrode 130, and is arranged at a longitudinal distance d5 + d6 + d7 above the second semiconductor material 110. The drain side end 170 is vertically separated from the second semiconductor material 110 by the first insulating material layer 155, the second insulating material layer 165, and the third insulating material layer 175. As will be further described later, the electric field between each of the gate electrode 135, the gate connection field plate 140 and the source connection field plate 145 and the heterojunction 115 is, under certain bias conditions, at the ends 150, 160, respectively. , 170 is the largest.

The gate electrode 135 can be electrically connected to the gate connection field plate 140 in a variety of different ways. In the illustrated embodiment, the connection between the gate electrode 135 and the gate connection field plate 140 is outside the cross section. In another embodiment, the gate electrode 135 and the gate connection field plate 140 may be formed of a single member having a substantially L-shaped cross section when viewed in the illustrated embodiment.

The source electrode 125 can be electrically connected to the source connection field plate 145 in a variety of different ways. In the illustrated embodiment, the source electrode 125 is electrically connected to the source connection field plate 145 by a source via member 180. In another embodiment, the source electrode 125 may be electrically connected to the source connection field plate 145 outside the cross section shown.

In the illustrated embodiment, the drain 130 is electrically connected to a set of drain via members 185, 190. The drain via members 185, 190 extend through the third insulating material layer 175 to the same vertical level as the source connection field plate 145, and thus function as an extension of the drain 130. Since the via member 190 is at the same vertical level as the source connection field plate 145, it is the extension of the drain 130 closest to the source connection field plate 145. The sides of the source connection field plate 145, including the bottom drain side end 170, are arranged at the same longitudinal level at a lateral distance d4 from the drain via member 190. In some embodiments, the lateral distance d4 is less than or equal to the distance required to maintain the device-specific breakdown voltage during the device-specific device life. In the illustrated embodiment, the source connection field plate 145 and the drain via member 190 are covered with a fourth insulating material layer 195. The fourth insulating material layer 195 extends a distance d8 from the upper surface of the third insulating material layer 175.

In the illustrated embodiment, both the source electrode 125 and the drain electrode 130 are placed directly on the top surface of the second semiconductor material 110 and are in electrical contact with it. This is not always the case. For example, in some embodiments, the source electrode 125 and / or the drain electrode 130 penetrates into the second semiconductor material 110. In some embodiments, the penetration is deep enough that the source electrode 125 and / or the drain electrode 130 contacts or even penetrates the heterojunction 115. As another example, in some embodiments, one or more penetrating adhesive metals or other conductive materials are associated with the source electrode 125 and / or the drain electrode 130 and one or both of the semiconductor materials 105, 110. It is arranged between.

In the illustrated embodiment, the gate electrode 135 is electrically insulated from the second semiconductor material 110 by a single electrically insulating layer 155 having a uniform thickness d5. This is not always the case. For example, in other embodiments, multiple layers may be used to insulate the gate electrode 135 from the second semiconductor material 110. As another example, a single or multiple layers with non-uniform thickness may be used to insulate the gate electrode 135 from the second semiconductor material 110.

Various features of the transverse channel HEMT100 can be formed by a variety of different materials. For example, the first semiconductor material 105 can be GaN, InN, Aln, AlGaN, InGaN, AlIn-GaN. In some embodiments, the first semiconductor material 105 may further comprise an arsenic-containing compound semiconductor, such as, for example, one or more of GaAs, InAs, AlAs, InGaAs, AlGaAs, InAlGaAs. The second semiconductor material 110 can be, for example, AlGaN, GaN, InN, Aln, InGaN, AlIn-GaN. The second semiconductor material 110 may further include arsenic-containing compound semiconductors such as one or more of GaAs, InAs, AlAs, InGaAs, AlGaAs, and InAlGaAs. The composition of the first and second semiconductor materials 105, 110 (which may also be referred to as the "active layer") is adjusted so that the two-dimensional electron gas 120 is formed by a heterojunction 115. For example, in some embodiments, the composition of the first and second semiconductor materials 105 and 110, the heterojunction 115 ¹⁰ 11 ^~10 14 ^{cm -2,} for example, in the heterojunction ^{115 5x10} 12 ~5x10 13 cm It can be adjusted to a sheet carrier density of ^-2 or 8x10 ^{12 to} 1.2x10 ¹³ cm- ² . The semiconductor materials 105, 110 may be formed above the substrate, for example gallium nitride, gallium arsenide, silicon carbide, sapphire, silicon, or above other substrates. The semiconductor material 105 can either be in direct contact with such a substrate or have one or more intervening layers present.

The source electrode 125, drain electrode 130, and gate electrode 135 can be formed from various conductors including metals such as, for example, Al, Ni, Ti, TiW, TiN, TiAu, TiAlMoAu, TiAlNiAu, TiAlPtAu or the like. The first insulating material layer 155 is, for example, aluminum oxide (Al ₂ O ₃ ), zirconium dioxide (ZrO ₂ ), aluminum nitride (Aln), hafon oxide (HfO ₂ ), silicon dioxide (SiO ₂ ), silicon nitride (SiO ₂ ). It can be formed from a variety of dielectrics suitable for forming gate insulators, including Si ₃ N ₄ ), silicon nitride (AlSiN), or other suitable gate dielectric materials. The second, third, and fourth insulating material layers 165, 175, and 195 can be formed from various dielectrics, including, for example, silicon nitride, silicon oxide, silicon oxynitride, or the like. The first, second, third, and fourth insulating material layers 155, 165, 175, 195, further, each of the layers 155, 165, 175, 195 is a second semiconductor material underneath. It may also be referred to as a "passivation layer" in that it prevents or prevents the formation and / or charging of surface states at each of 110 or layers 155, 165, 175.

In some embodiments, the second, third, and fourth insulating material layers 165, 175, and 195 are insulating materials (so that they reach a steady state after long-term operation with specific operating parameters). It has a quality and composition adjusted so that the number of charge defects per area in layers 165, 175, 195 is less than the sheet carrier density in the heterojunction. In other words, the sum of the product of each of the three-dimensional defect densities of the insulating material layers 165, 175, and 195 and the thickness of each of the layers is less than the (two-dimensional) sheet carrier density in the heterojunction 115. For example, in some embodiments, the number of charge defects per area in the insulating material layers 165, 175, 195 is less than 20% or less than 10% of the sheet carrier density in the heterojunction 115. In some embodiments, the HEMTs 100 and other HEMTs described herein include an intermediate layer, such as an Aln intermediate layer.

The source electrode 125 is arranged at a lateral distance from the drain electrode 130 to d2. In some embodiments, the lateral distance d2 is 5 to 50 micrometers, for example 9 to 30 micrometers. In some embodiments, the lateral distance d1 is 1 to 5 micrometers, for example 1.5 to 3.5 micrometers. In some embodiments, the thickness of the third insulating material layer 175 is 0.2 to 1 micrometer, for example 0.35 to 0.75 micrometers. In some embodiments, the lateral distance d4 is 1 to 8 micrometers, for example 2 to 6 micrometers. In some embodiments, the thickness of the fourth insulating material layer 195 is 0.4 to 3 micrometers, for example 0.5 to 2 micrometers. In some embodiments, the lateral distance d3 is 1-10 micrometers, for example 2.5-7.5 micrometers.

FIG. 2 is a schematic cross-sectional view of the lateral channel HEMT200. In addition to the semiconductor materials 105, 110, electrodes 125, 130, 135, and via members 180, 185, 190, the HEMT 200 includes a vertically layered field plate structure 205. The field plate structure 205 is a triple field plate structure including not only the gate connection field plate 140 and the source connection field plate 145 but also the second source connection plate 210. The second source connection plate 210 is electrically connected to the source electrode 125. The second source connection plate 210 covers the gate electrode 135, the gate field plate 140, and the source connection field plate 145.

In some embodiments, the second source connection plate 210 functions as a so-called "shield wrap". As mentioned above, some HEMTs are affected by parasitic dc-rf dispersion, which is believed to be caused, at least in part, by the exchange of surface charges with the surrounding environment during high operation. In particular, the surface states charge and discharge with a relatively slow response time, affecting the high frequency operation of HEMTs. Metal shield wraps can mitigate or eliminate these effects by improving the surface state shield and preventing surface charge exchange. In some embodiments, the second source connection plate 210 is an electric field in the HEMT 200, eg, a heterojunction 115 and, eg, a bottom drain side end 170 of the source connection field plate 145 or a bottom drain of the gate connection field plate 310. It functions as a field plate that reduces the peak value of the electric field between the side end 320 and the electric field (FIG. 3). Further, as described below, in some embodiments, the second source connection plate 210 further functions to deplete the charge carriers of the heterojunction 115. In some embodiments, the second source connection plate 210 serves a plurality of functions, i.e. as two or more shield wraps, as a field plate, and to deplete the heterojunction 115. The particular function of the second source connection plate 210 in any device is a function of any number of various geometric parameters, material parameters, and operating parameters. In the present specification, the source connection plate 210 is simply referred to as a "source connection plate" because the source connection plate 210 may perform one or more roles.

In the illustrated embodiment, the second source connection plate 210 has a substantially rectangular cross section. The second source connection plate 210 includes a bottom drain side end 220. The drain side end 220 has a lateral distance d0 + d1 + d3 + d11 from the side of the source electrode 125 toward the drain electrode 130, and is arranged at a longitudinal distance d5 + d6 + d7 + d8 above the second semiconductor material 110. In some embodiments, the lateral distance d0 + d1 + d3 + d11 is more than twice the longitudinal distance d5 + d6 + d7 + d8. For example, the lateral distance d0 + d1 + d3 + d11 can be three times or more of d5 + d6 + d7 + d8. The drain side end 220 is formed in the vertical direction from the second semiconductor material 110 by the first insulating material layer 155, the second insulating material layer 165, the third insulating material layer 175, and the fourth insulating material layer 195. Is separated from each other. As will be further described later, the electric field between the second source connection plate 210 and the heterojunction 115 is greatest at the bottom drain side end 220 under certain bias conditions.

The second source connection plate 210 can be electrically connected to the source electrode 125 in a variety of different ways. In the illustrated embodiment, the source electrode 125 is electrically connected to the second source connection plate 210 by a source via member 225. In another embodiment, the source electrode 125 may be electrically connected to the second source connection plate 210 outside the cross section shown.

In the illustrated embodiment, the drain 130 is electrically connected to another drain via member 230 via via members 185, 190. The drain via member 230 extends through the fourth insulating material layer 195 to the same vertical level as the second source connection plate 210, and thus functions as an extension of the drain 130. Since the via member 230 is at the same vertical level as the second source connection plate 210, it is the extension of the drain 130 closest to the second source connection plate 210. The sides of the second source connection plate 210, including the bottom drain side end 220, are disposed at the same vertical level at a lateral distance of d9 from the drain via member 230. In the illustrated embodiment, the second source connection plate 210 and the drain via member 230 are covered with a fifth insulating material layer 245. The fifth insulating material layer 245 extends a distance d10 from the upper surface of the fourth insulating material layer 195.

In some embodiments, d1 + d3 + d4 is 5 to 35 micrometers, for example 8 to 26 micrometers. In some embodiments, the lateral distance d9 is 1-10 micrometers, eg 2-6 micrometers. In some embodiments, the second, third, fourth, and fifth insulating material layers 165, 175, 195, and 245 are brought into steady state (after long-term operation with specific operating parameters). It has a quality and composition adjusted so that the number of charge defects per area in the insulating material layer 165, 175, 195, 245 is less than the sheet carrier density in the heterojunction. In other words, the sum of the products of the respective three-dimensional defect densities of the insulating material layers 165, 175, 195, and 245 and the respective thicknesses of the layers is less than the sheet carrier density in the (two-dimensional) heterojunction 115. For example, in some embodiments, the number of charge defects per area in the insulating material layers 165, 175, 195, 245 is less than 20%, eg, less than 10%, of the sheet carrier density in the heterojunction 115.

FIG. 3 is a schematic cross-sectional view of the lateral channel HEMT300. In addition to the semiconductor materials 105, 110, electrodes 125, 130, 135, and via members 180, 185, 190, 225, 230, the HEMT 300 includes a vertically layered field plate structure 305. The field plate structure 205 is a triple field plate structure including not only the gate connection field plate 140 and the second source connection plate 210 but also the second gate connection field plate 310. The second gate connection field plate 310 is electrically connected to the gate electrode 135.

In the illustrated embodiment, the second gate connection field plate 310 has a substantially rectangular cross section. The second gate connection field plate 310 includes a bottom drain side end 320. The drain side end portion 320 has a lateral distance d0 + d1 + d3 from the side portion of the source electrode 125 toward the drain electrode 130, and is arranged at a longitudinal distance d5 + d6 + d7 above the second semiconductor material 110. The drain side end portion 320 is vertically separated from the second semiconductor material 110 by the first insulating material layer 155, the second insulating material layer 165, and the third insulating material layer 175. As will be further described later, the electric field between the second connection field plate 310 and the heterojunction 115 is greatest at the bottom drain side end 320 under certain bias conditions.

The second gate connection field plate 310 can be electrically connected to the gate electrode 135 in a variety of different ways. In the illustrated embodiment, the second gate connection field plate 310 is electrically connected to the gate connection field plate 140 by a gate via member 325. Further, the gate connection field plate 140 is connected to the gate 125 outside the cross section shown. In another embodiment, the second gate connection field plate 310 may be electrically connected to the gate connection field plate 140 outside the cross section shown and / or with the gate electrode 135 and the gate connection field plate 140. Can be connected within the illustrated cross section.

During operation, HEMTs such as HEMTs 100, 200, and 300 are switched between an on state and an off state by applying a bias to their respective gate electrodes 135. In general, HEMTs 100, 200, and 300 are depletion type devices that conduct when the potential difference between gate and source is zero. The gate is negatively biased with respect to the source to switch the depletion type device off. In many applications, it is practically desirable that the on-resistance of the HEMT is low, for example, to the extent that the power loss of the HEMT does not increase undesirably and / or to the extent that the HEMT does not become excessively hot. In general, the gate is positively biased relative to the source to reduce the on-resistance of the HEMT.

In practice, even if, in theory, an overly large gate-source potential difference has some beneficial effects, such as further reducing the on-resistance of the HEMT, such an overly large gate-source It is not possible to apply an interpotential difference. In particular, the gate-source potential difference is constrained by the interaction of HEMT geometric, material, and operating parameters. For example, excessive gate-source potential differences can result in degradation and / or dielectric breakdown of intervening materials of a particular thickness and density, electron leakage to the second semiconductor layer 110 and capture in the second semiconductor layer 110. It can also result in the capture of hot electrons in the first dielectric layer 155. For this reason, the operating range of the gate-source potential difference is limited to a range of values for a given device with a range of temperatures and other operating parameters. The operating range of this gate-source potential difference is called the available gate swing amplitude. In many GaN HEMT devices, potential differences as large as single digit to 10 volts are applied between the gate and source. Therefore, the available gate swing amplitude is generally in the approximately 10 volt range. For example, in some GaN HEMT devices, the available gateswing amplitude is 30 volts or less, for example 20 volts or less. In depletion-type HEMT, the gate swing amplitude available, in the range of from the smallest threshold of negative off-state, to a positive upper limit. In an enhancement device that is off when the gate-source potential difference is zero, the available gateswing amplitudes range from the smaller threshold of zero potential difference to the upper limit of the maximum positive value. Can be taken.

In contrast, in many power switching applications, the source-drain potential difference ΔV _SD of the HEMT can be in the approximately 100 volt range, for example above 500 V _DC , for example about 650 V _DC . In such applications, when the applied gate swing amplitude is in the 10 volt range, both the source-drain potential difference magnitude ΔV _SD and the source-gate potential difference magnitude ΔV _SG are gate-source potential differences. Significantly larger than the size of. With this in mind, the schematic representation of the graph below is interchangeable ends 170, 320, despite the fact that there will be differences (in real-world equipment).

4A and 4B are graphs 405 and 410 schematically representing the voltage and electric field at the heterojunction between the source and drain of the HEMTs of some embodiments that are off, respectively. Embodiments of HEMTs include at least a double field plate structure (eg, FIG. 1) or a triple or more field plate structure (eg, FIGS. 2, 3). In graphs 405 and 410, the voltage and electric field are not limited, but geometric parameters (including, for example, the number, dimensions, and configurations of HEMT features), material parameters (eg, material dielectric constant, material density, etc.). Functions of various parameters including work function, dopant concentration, defect concentration, surface state composition, and surface state concentration, as well as operating parameters (including, for example, temperature, gate voltage, and source-drain voltage). It is understood that it is a very schematic diagram in that it is. Moreover, even in the case of a single device, such parameters change over time, for example, as the device ages or as its operating state changes. obtain. Therefore, the slope of the line, the size of the peaks, the number of peaks, and other characteristics will vary depending on, for example, a specific device and operating conditions. Therefore, graphs 405 and 410 should be construed as schematics for normative and exemplary purposes.

Graph 405 includes axis 410 and abscissa 415. The vertical position along the axis 410 represents the voltage. The lateral position along the abscissa 415 represents the lateral position along the HEMT heterojunction between the source and drain. Graph 420 includes axis 425 and abscissa 430. The vertical position along the axis 425 represents the magnitude of the electric field. The lateral position along the abscissa 430 represents the lateral position along the HEMT heterojunction between the source and drain. The lateral positions along the abscissas 415 and 430 correspond to the ends 150, 160, 170, 320 of HEMTs 100, 200, 300 (FIGS. 1, 2, and 3) for illustrative purposes.

Under the parameters shown, it is observed that the heterojunction is substantially conductive in the vicinity of the source 420 and is a voltage approximately equal to the source voltage VS. Therefore, the electric field of 420 near the source is about zero. Under the indicated bias conditions (the gate is biased to locally deplete the charge carriers from the heterojunction), the electrical impedance per unit length of the heterojunction increases near the gate, and The local high value is reached almost immediately below the bottom drain side end 150 of the gate. Local depletion of the charge carrier in the vicinity of the bottom drain side end 150 of the gate causes a voltage change of 425 and a localized value of 430 of the electric field.

Depletion of charge carriers from heterojunctions by the gate decreases towards the drain. Therefore, both the change in potential per unit length and the heterojunction electric field are reduced. However, under exemplary parameters (gate connection field plates are further disposed and biased to locally deplete charge carriers from the heterojunction), electricity per unit length of the heterojunction. Impedance increases as well and reaches a local high value approximately just below the bottom drain side end 160 of the gate connection field plate. An increase in electrical impedance in the vicinity of the gate connection field plate results in a relatively large change in voltage per unit length of 435 and a local maximum of 440 in the electric field.

Depletion of charge carriers from heterojunctions with gate-connected field plates is also reduced towards the drain. Therefore, both the change in potential per unit length and the heterojunction electric field are reduced. However, under exemplary parameters (the source connection field plate is further disposed and biased to locally deplete the charge carriers from the heterojunction), the electrical impedance per unit length of the heterojunction. Also increases and reaches a local high value approximately directly below the bottom drain side end 170 of the source connection field plate 145 or the bottom drain side end 320 of the gate connection field plate 310. An increase in electrical impedance in the vicinity of the source connection field plate results in a relatively large change in voltage per unit length of 445 and a local maximum of 450 in the electric field.

Under exemplary parameters, charge carrier depletion from heterojunctions with source connection field plates is also reduced towards the drain. Heterojunction is substantially becomes conductive in the vicinity 455 of the drain, and it is observed a voltage substantially equal to the drain voltage V _D. Therefore, the electric field in the vicinity of the drain 455 is about zero. The potential difference between all sources and drains ΔV _SD is supported over the lateral length of the heterojunction and the HEMT is in the off (non-conductive) state. As mentioned above, FIGS. 4A and 4B are schematics for normative and exemplary purposes. Between source and drain in other ways, including other HEMTs under other operating conditions, with additional or less peaks, peaks of different slopes, and peaks of various peaks, as well as other characteristics. It can support the potential difference ΔV _SD .

5A and 5B are graphs 505 and 510, which schematically represent the voltage and electric field at the heterojunction between the source and drain of the HEMTs of some embodiments that are on, respectively. Embodiments of HEMTs may include a double field plate structure (eg, FIG. 1) or a triple or more field plate structure (eg, FIGS. 2, 3). Graphs 505 and 510 are also schematics, voltage and electric field are functions of various parameters, and such parameters may change over time.

Graph 505 includes axis 510 and abscissa 515. The vertical position along the axis 510 represents the voltage. The lateral position along the abscissa 515 represents the lateral position along the HEMT heterojunction between the source and drain. Graph 520 includes axis 525 and abscissa 530. The vertical position along the axis 525 represents the magnitude of the electric field. The lateral position along the abscissa 530 represents the lateral position along the HEMT heterojunction between the source and drain. The lateral positions along the abscissa 515, 530 correspond to the ends 150, 160, 170, 320 of HEMTs 100, 200, 300 (FIGS. 1, 2, and 3) for illustrative purposes.

In the on-state under the indicated geometric, material and operating parameters, the heterojunction is conductive and the source and drain are at substantially the same voltage. However, even under the parameters shown, the heterojunction has a finite non-zero resistance and the source and drain voltages are not the same. For illustration purposes, the voltage 535 has a slight but uniformly rising slope and a minimal but uniform non-zero, as is reasonable if the heterojunction has an ideally uniform resistivity over the entire length of the channel. It is displayed with a zero value electric field 540. This is not always the case. For example, the finite resistivity of a heterojunction, even if conductive, varies depending on the lateral position due to local differences in contact potential difference, carrier density, defect density, and / or other parameters. There may be.

As another example, for example, if the number of carriers in a heterojunction is relatively small compared to the current that would be conducted by an ideal conductor, the current in the heterojunction would be a particular geometric parameter, material parameter, And can be a limited space charge under operating parameters. A relatively large source-drain potential difference ΔV _SD and electric field can occur. For example, under certain parameters, for a given drain current level, above the knee voltage (ΔV _SD ≥ V _knee ), a relatively large electric field is applied below the gate electrode towards the drain, even from the non-depleted region. Also extends laterally.

In some embodiments, the distance d3, which characterizes the lateral extension of the field plates 145, 310 towards the drain from the bottom drain side end 160 of the gate connection field plate 140, is this relatively large towards the drain. It is less than the lateral spread of the electric field. Such a limitation on the lateral extension of the field plates 145, 310 may reduce the electric field generated between the field plates 145, 310 and the heterojunction 115. In particular, for the source connection field plate 145, the potential difference ΔV _SD between all sources and drains is the first insulating material layer 155, the second insulating material layer 165, and the third insulating material layer 175 along the length d3. It will not be supported by the whole part of. For the gate connection field plate 310, the potential difference between all gates and drains is the entire portion of the first insulating material layer 155, the second insulating material layer 165, and the third insulating material layer 175 along the length d3. Will not be supported by. By reducing the electric field in this region, the breakdown voltage and lifetime of the HEMT can be improved.

Therefore, as mentioned above, FIGS. 5A and 5B are also schematics for normative and exemplary purposes. The vertical position of the voltage 535 along the shaft 510 will be determined depending on the placement of the HEMTs, for example, whether the HEMTs are placed on the higher side or the lower side of the load.

6A and 6B show HEMTs of some embodiments that are off for fixed source and gate potentials, respectively, for a variety of different and distinct drain potentials VD1, VD2, VD3, VD4. 605, 620 are graphs schematically showing the voltage and electric potential at the heterojunction between the source and drain of. Graphs 605 and 620 are very schematic diagrams shown for normative and exemplary purposes. Embodiments of HEMTs may include a double field plate structure (eg, FIG. 1) or a triple or more field plate structure (eg, FIGS. 2, 3).

Graph 605 includes axes 610 and abscissa 615. The vertical position along the axis 610 represents the voltage. The lateral position along the abscissa 615 represents the lateral position along the HEMT heterojunction between the source and drain. Graph 620 includes axis 625 and abscissa 630. The vertical position along the axis 625 represents the magnitude of the electric field. The lateral position along the abscissa 630 represents the lateral position along the HEMT heterojunction between the source and drain. The lateral positions along the abscissa 615, 630 correspond to the ends 150, 160, 170, 320 of HEMT 100, 200, 300 (FIGS. 1, 2, 3) for illustration purposes.

In the off state, a source-drain potential difference ΔV _SD is supported over the entire transverse length of the heterojunction. However, the degree of local depletion of the charge carrier may vary depending on the geometric, material and operating parameters of the HEMT. Correspondingly, the potential difference ΔV _SD between the source and drain changes, so that the voltage change 425 and the local maximum value 430 in the vicinity of the bottom drain side end 150 and the voltage change 435 in the vicinity of the bottom drain side end 160 And the local highs 440, and the voltage changes 445 and local highs 450 in the vicinity of the bottom drain side ends 170, 320 can also be different.

Graphs 605 and 620 are very schematic, but the local maximum value 430 of the electric field near the bottom drain side end 150 of the gate 135 is the larger source-drain potential difference ΔV displayed in graph 620. Note that _SD begins to saturate. In other words, with a relatively small source-drain potential difference ΔV _SD (eg, with less than VD1 and drain voltage between VD1 and VD2), an increase in source-drain potential difference ΔV _SD also increases the bottom drain of the gate 135. It results in an increase in the local magnitude 430 of the electric field near the side end 150. Symmetrically, at a relatively large source-drain potential difference ΔV _SD (eg, drain voltage between VD3 and VD4), the increase in source-drain potential difference ΔV _SD is at the bottom drain side end 150 of the gate 135. At a local maximum of 430 electric fields in the vicinity, it results in a smaller increase or even no increase. This saturation or "peaking out" of the gradual change in the local peak 430 of the electric field with increasing drain potential leads to complete depletion of charge carriers near the bottom drain side end 160 of the gate connection field plate 140. Correspond.

In some embodiments, the geometry of the HEMT and such that the tapering of the gate end electric field peaks under common operating conditions, for example, at room temperature of 150 degrees Celsius or at room temperature of 125 degrees Celsius. The properties of the material can be adjusted. For example, the geometric and material properties of the HEMT can be adjusted so that the gradual increase in the gate end electric field peaks at a drain potential with respect to the source that is greater than the absolute value of the gate swing amplitude. Therefore, at least some of the geometric and material properties that define the gate swing amplitude are associated with the gradual increase of the gate end electric field, and by themselves at least some of its same geometric and material properties. Partially defined by some interaction. By adjusting the geometric and material properties in this way, the maximum electric field in the channel near the drain side end 150 of the gate 135 can be limited, thus deep in the center of the semiconductor material 105 and / or 110. Reduces or prevents ionization of. This even reduces or even prevents the associated dispersion or disintegration effect, and reduces or eliminates the potential for avalanche breakdown in the semiconductor materials 105 and / or 110.

As another example, in some embodiments, the nature of the geometric properties and the material of the HEMT is greater than twice the absolute value of the gate swing amplitude, the drain potential with respect to the source, for example, the gate swing amplitude of the absolute value At 2-5 times or 3-4 times the absolute value of the gate swing amplitude, the gradual increase in the gate end electric field under the same operating conditions can be adjusted to peak. By adjusting such geometrical properties and material properties in this way, the above benefits are more likely to be achieved.

FIG. 7 shows the source and drain of some embodiments of HEMT in the off state for a fixed source and gate potential with a variety of different and distinct drain potentials VD4, VD5, VD6, VD7. FIG. 720 is a graph 720 schematically showing the electric field at the heterojunction between the two. Graph 720 is a very schematic diagram shown for normative and exemplary purposes. Embodiments of HEMTs may include a double field plate structure (eg, FIG. 1) or a triple or more field plate structure (eg, FIGS. 2, 3).

Graph 720 includes axis 725 and abscissa 730. The vertical position along the axis 725 represents the magnitude of the electric field. The lateral position along the abscissa 730 represents the lateral position along the HEMT heterojunction between the source and drain. The lateral positions along the abscissa 730 correspond to the ends 150, 160, 170, 320 of HEMTs 100, 200, 300 (FIGS. 1, 2, 3) for illustration purposes.

In the off state, a source-drain potential difference ΔV _SD is supported over the entire transverse length of the heterojunction. However, the degree of local depletion of the charge carrier may vary depending on the geometric, material and operating parameters of the HEMT.

Graph 720 is a very schematic diagram, but note the following:
-The locality 430 of the electric field near the bottom drain side end 150 of the gate 135 saturates at all of the source-drain potential differences ΔV _SD shown. And-The local value 440 of the electric field near the bottom drain side end 160 of the gate connection field plate 140 begins to saturate with the larger source-drain potential difference ΔV _SD shown in graph 720.

In other words, with a relatively small source-drain potential difference ΔV _SD (eg, with less than VD4 and with a drain voltage between VD4 and VD5), an increase in the source-drain potential difference ΔV _SD also increases the gate connection field plate 140. It results in an increase in the local magnitude of 440 of the electric field near the bottom drain side end 160 of the. Symmetrically, with a relatively large source-drain potential difference ΔV _SD (eg, at the drain voltage between VD6 and VD7), an increase in the source-drain potential difference ΔV _SD is on the bottom drain side of the gate connection field plate 140. It results in a smaller increase or no increase in the locality 440 of the electric field near the end 160. This saturation or "peaking out" of the gradual change in the local peak 440 of the electric field with increasing drain potential corresponds to the complete depletion of charge carriers in the vicinity of the bottom drain side ends 170, 320, respectively. ..

In some embodiments, the geometric properties of the HEMT so that the gradual increase in the gate end electric field peaks under common operating conditions, such as at room temperature of 150 degrees Celsius or at room temperature of 125 degrees Celsius. And the properties of the material (including distance d3) can be adjusted. For example, the geometric properties of the HEMT and the properties of the material (including the distance d3) are adjusted so that the gradual increase of the gate connection field plate peaks at a drain potential larger than the drain potential where the gradual increase of the gate end electric field peaks. Can be done. For example, this potential difference can be a potential difference greater than twice the drain potential at which the gradual increase in the gate end electric field peaks, for example, a potential difference of 3 to 5 times the drain potential at which the gradual increase in the gate end electric field peaks. Thus, at least some of the geometric and material properties that define the gradual peaking of the gate end electric field are associated with the gradual peaking of the gate connection field plate, which itself has the same geometrical properties and Partially defined by at least some interaction of the properties of the material. By adjusting the geometric and material properties in this way, the maximum electric field in the channel near the drain side end 160 of the gate connection field plate 140 can be limited, thus limiting the semiconductor material 105 and / or 110. Reduces or prevents deep central ionization in. This even reduces or even prevents the associated dispersion or disintegration effect and reduces or eliminates the potential for avalanche breakdown in the semiconductor materials 105 and / or 110.

As another example, in some embodiments, the gradual increase in the gate end electric field is greater than 2.5 times the drain potential that peaks, for example, 5 times the drain potential where the gradual increase in the gate end electric field peaks. Alternatively, the geometric and material properties of the HEMT so that the gradual increase in the gate end field plate peaks at the drain potential relative to the source, where the gradual increase in the gate end electric field is 10 times the drain potential that peaks. (Including distance d3) can be adjusted. By adjusting the geometrical properties and the properties of the material in this way, the above benefits are more likely to be achieved.

FIG. 8 shows the source and drain of some embodiments in the off state for fixed source and gate potentials with a variety of different and distinct drain potentials VD4, VD5, VD6, VD7. FIG. 820 is a graph 820 schematically showing the electric field at the heterojunction between the two. Graph 720 is a very schematic diagram shown for normative and exemplary purposes. Embodiments of HEMTs may include a double field plate structure (eg, FIG. 1) or a triple or more field plate structure (eg, FIGS. 2, 3).

Graph 820 includes axis 825 and abscissa 830. The vertical position along the axis 825 represents the magnitude of the electric field. The lateral position along the abscissa 830 represents the lateral position along the HEMT heterojunction between the source and drain. The lateral positions along the abscissa 830 correspond to the ends 150, 160, 170, 320 of HEMTs 100, 200, 300 (FIGS. 1, 2, and 3) for illustrative purposes.

In the off state, a source-drain potential difference ΔV _SD is supported over the entire transverse length of the heterojunction. However, graph 820, which is a very schematic diagram, saturates the local maximum value 440 of the electric field near the bottom drain side end 160 of the gate connection field plate 140 at a larger source-drain potential difference ΔV _SD . The electric field extending laterally from the bottom drain side end 160 of the gate connection field plate 140 toward the drain is the electric field extending laterally from the bottom drain side ends 170 and 320 toward the source. Note that it does not reach. In other words, with a relatively small source-drain potential difference ΔV _SD (eg, at less than VD4 and at a drain voltage between VD4 and VD5), some 805 of the heterojunction remains substantially conductive, and , The electric field in some 805 is about zero. Symmetrically, with a relatively large source-drain potential difference ΔV _SD (eg, between VD6 and VD7 and at a drain voltage greater than VD7), the drain side ends 160 and the drain side ends 170, 320 overlap. The local depletion (and associated electric field) that arises from it, as well as the conductivity of some 805, is reduced.

Part of the heterojunction 805 is between source and drain until the locality 440 of the electric field near the bottom drain side end 160 of the gate connection field plate 140 (under general operating conditions) begins to saturate. With increasing potential difference ΔV _SD , the geometric properties of the HEMT and the properties of the material (including the distance d3) can be adjusted so that they remain substantially conductive. An example of such operating conditions is, for example, at room temperature of 150 degrees Celsius or at room temperature of 125 degrees Celsius. By adjusting the geometrical and material properties, the maximum electric field in the channel near the drain side end 160 of the gate connection field plate 140 can be limited and therefore in the semiconductor material 105 and / or 110. Reduces or prevents ionization deep in the center.

FIG. 9 shows a heterojunction between the source and drain of some embodiments of HEMT in the off state for a fixed source and gate potential, with a variety of different and distinct drain potentials. FIG. 920 is a graph 920 schematically showing an electric potential. Graph 920 is a very schematic diagram shown for normative and exemplary purposes. Embodiments of HEMT include triple or more field plate structures (eg, FIGS. 2, 3).

Graph 920 includes axis 925 and abscissa 930. The vertical position along the axis 925 represents the magnitude of the electric field. The lateral position along the abscissa 930 represents the lateral position along the HEMT heterojunction between the source and drain. The lateral position along the abscissa 930 corresponds to the ends 150, 160, 170, 320, 220 of HEMT200, 300 (FIGS. 2 and 3) for illustrative purposes.

In the off state, a source-drain potential difference ΔV _SD is supported over the entire transverse length of the heterojunction. Under exemplary parameters, the bottom drain side end 220 of the second source connection plate 210 further depletes the charge carriers from the heterojunction and creates an electric field near the drain 455. Therefore, due to the longitudinal voltage difference between the heterojunction and the second source connection plate 210 (under general operating conditions), some of the heterojunctions near the drain 455 are depleted. As such, the geometrical properties of HEMTs and the properties of materials can be adjusted. An example of such operating conditions is, for example, at room temperature of 150 degrees Celsius or at room temperature of 125 degrees Celsius.

By adjusting the geometric and material properties in this way, the potential difference between the heterojunction and the second source connection plate 210, and as a result the electric field, while the device is off. , Can be reduced. In particular, part of the source-drain potential difference [Delta] V _SD is in the vicinity 455 of the drain so decreases along the heterojunction 115, all source-drain potential difference [Delta] V _SD is the second source connection plate 210 second It is not applied between the heterojunction 115 below the source connection plate 210. Instead, for example, there is a smaller potential difference that reduces the possibility of charge injection into the intervening insulating material (s) and / or dielectric breakdown.

In some embodiments, the HEMT is tuned to operate with at least the largest specified source-drain potential difference ΔV _SD between the heterojunction and the second source connection plate 210 for at least a short period of time. Has geometrical properties and material properties. In particular, HEMTs can consume a relatively large percentage of their operating life in the off state, but during switching, potentials close to the maximum operational source-drain potential difference ΔV _SD are transient. Appears between the heterojunction and the second source connection plate 210. Although not intended to be bound by any theory, the depletion and (re) accumulation process in heterojunctions may not occur uniformly along the entire lateral length of the heterojunction. Conceivable. For example, in the context of switching between the off and on states, part of the heterojunction 115 near the drain may (re) accumulate charge faster than the rest of the heterojunction 115. In this case, the heterojunction in the vicinity of the drain 455 can be conductive before the rest of the heterojunction 115. During this transient, the drain voltage V _D can spread within the neighborhood 455 and the total source-drain potential difference ΔV _SD is with the lower portion of the second source connection plate 210 and the heterojunction 115. Will be supported between.

Several embodiments have been described. However, it is understood that various changes apply. For example, all the illustrated embodiments are transverse channel HEMTs, but the same technique can be applied to longitudinal channel HEMTs if longitudinal heterojunctions can be formed. Therefore, other embodiments are within the scope of the appended claims.

Claims (23)

HEMT, the HEMT
A first semiconductor material and a second semiconductor material arranged so as to form a heterojunction at a position where a two-dimensional electron gas is generated;
A source electrode, a drain electrode, and a gate electrode, the gate electrode is arranged so as to adjust the conduction in the heterojunction between the source electrode and the drain electrode, and the gate electrode is on the drain side. The source electrode, the drain electrode, and the gate electrode having an end;
A gate connection field plate disposed above the drain side end of the gate electrode and extending laterally toward the drain electrode; and above the drain side end of the gate connection field plate. A second field plate extending laterally toward the drain electrode;
With
The HEMT is configured as follows, i.e.
a) In the off state of the HEMT and
b) The potential difference between the source electrode and the drain electrode that exceeds the absolute value of the gate swing amplitude .
As the depletion charge carriers from a portion of the heterojunction in the vicinity of the drain-side end portion of the front Symbol gate connected field plate, the HEMT is constituted, and, said depletion of charge carriers, the At the potential difference between the source electrode and the drain electrode that exceeds the absolute value of the gate swing amplitude , the lateral electric field in the heterojunction near the drain side end of the gate electrode is saturated . The HEMT is configured and
In the off state of the HEMT ,
The first electric field in the heterojunction extends from the drain side end of the gate connection field plate toward the drain side .
The second electric field in the heterojunction extends from the drain side end of the second field plate toward the source side .
The first electric field first determines the potential difference between the source electrode and the drain electrode in which the charge carrier is depleted from a part of the heterojunction in the vicinity of the drain side end of the second field plate. It overlaps with the second electric field only by the potential difference between the source electrode and the drain electrode that exceeds.
The HEMT is configured so that
HEMT. The charge carrier has a potential difference between the source electrode and the drain electrode that is 2 to 5 times the absolute value of the gate swing amplitude , and the hetero in the vicinity of the drain side end of the gate connection field plate. Depleting from said part of the junction,
HEMT of claim 1. The charge carrier is depleted by a potential difference between the source electrode and the drain electrode that is 3-4 times the absolute value of the gate swing amplitude .
HEMT of claim 1. a) In the off state of the HEMT and
b) The potential difference between the source electrode and the drain electrode that exceeds the potential difference at which the charge carrier is depleted from the part of the heterojunction in the vicinity of the drain side end of the gate connection field plate.
The charge carrier is depleted from a portion of the heterojunction in the vicinity of the drain side end of the second field plate, and the depletion of the charge carrier is in the vicinity of the drain side end of the gate connection field plate. wherein Ru saturates the lateral electric field at the heterojunction in,
HEMT of claim 1. The potential difference wherein the portion from which the charge carriers of the heterojunction in the vicinity of the drain end of the second field plate is depleted is, the in the vicinity of the drain end of the gate connection field plate The charge carrier is depleted from the part of the heterojunction, which is 3 to 5 times the potential difference.
HEMT of claim 4. A third field plate, which is disposed above the drain side end of the second field plate and extends laterally toward the drain electrode.
Further prepare
HEMT of claim 1. a) In the off state of the HEMT and
b) The source electrode and the drain exceed the potential difference between the source electrode and the drain electrode in which the charge carrier is depleted from a part of the heterojunction in the vicinity of the drain side end portion of the second field plate. The potential difference between the electrodes
A portion of the heterojunction in the vicinity of the drain electrode is depleted due to a longitudinal voltage difference between the heterojunction and the third field plate.
HEMT of claim 6. The third field plate is a source connection field plate.
HEMT of claim 6. The first electric field first determines the potential difference between the source electrode and the drain electrode in which the charge carrier is depleted from a part of the heterojunction in the vicinity of the drain side end of the second field plate. Only the greater potential difference between the source electrode and the drain electrode overlaps with the second electric field.
HEMT of claim 1. The HEMT comprises one or more insulating material layers above the first and second semiconductor materials;
Sheet carrier density occurs in the heterojunction; and
After long-term operation with specific operating parameters and after reaching steady state, the number of charge defects per unit area in the insulating material layer is less than the sheet carrier density.
HEMT of claim 1. The number of charge defects per unit area in the insulating material layer is less than 10% of the sheet carrier density.
HEMT of claim 10. The first and second semiconductor materials are GaN and AlGaN, respectively.
HEMT of claim 1. The gate electrode is separated from the second semiconductor material by an aluminum silicon nitride layer.
The HEMT of claim 12. HEMT, the HEMT
A first semiconductor material and a second semiconductor material arranged so as to form a heterojunction at a position where a two-dimensional electron gas is generated;
A source electrode, a drain electrode, and a gate electrode, the gate electrode is arranged so as to adjust the conduction in the heterojunction between the source electrode and the drain electrode, and the gate electrode is a drain side end. The source electrode, the drain electrode, and the gate electrode having a portion;
A gate connection field plate disposed above the drain side end of the gate electrode and extending laterally toward the drain electrode; and above the drain side end of the gate connection field plate. A second field plate extending laterally toward the drain electrode,
With
In the off state of the HEMT , a), b) and c) are made, that is,
a) The first electric field in the heterojunction extends from the drain side end of the gate connection field plate toward the drain side.
b) The second electric field in the heterojunction extends from the drain side end of the second field plate toward the source side.
c) The first electric field is first generated between the source electrode and the drain electrode, where the charge carrier is depleted from a part of the heterojunction in the vicinity of the drain side end of the second field plate. and that only overlap the second field at a potential difference between the source electrode above the potential difference between the drain electrode,
The HEMT is configured so that
HEMT. A third field plate disposed above the drain-side end of the second field plate and extending laterally toward the drain electrode is further provided.
HEMT of claim 14. a) In the off state of the HEMT and
b) The source electrode and the drain exceed the potential difference between the source electrode and the drain electrode in which the charge carrier is depleted from a part of the heterojunction in the vicinity of the drain side end portion of the second field plate. The potential difference between the electrodes
A portion of the heterojunction in the vicinity of the drain electrode is depleted due to a longitudinal voltage difference between the heterojunction and the third field plate.
HEMT of claim 15. substrate;
A first active layer disposed above the substrate;
The second active layer, which is arranged on the first active layer so that a transverse conductive channel is generated between the first active layer and the second active layer. 2 active layers;
A source electrode disposed above the second active layer and a drain electrode disposed above the second active layer;
A first passivation layer disposed above the second active layer;
A gate electrode disposed above the first passivation layer;
A second passivation layer disposed above the gate electrode;
A gate field plate extending for a first distance beyond the end of the gate electrode closest to the drain electrode, wherein the gate field plate is disposed on the second passivation layer. The gate field plate, defined by the metal pattern of the gate, wherein the first metal pattern extends laterally above the entire gate electrode;
A third passivation layer disposed above the gate field plate; and a second field plate, which is a source field plate defined by a second metal pattern disposed on the third passivation layer.
With
The second field plate is electrically connected to the source electrode and
Said second field plate extend laterally above the entire first metal pattern, and, beyond the end closest said first metal pattern and the gate field plate to said drain electrode It extends laterally for the second distance,
The second metal pattern and the end of the second field plate are separated by a third distance from the first extending portion of the drain electrode adjacent to the second field plate.
When a portion of the transverse conducting channel of the gate electrode lower than the absolute value of the available gate swing amplitude above a threshold value for a large first drain bias is pinched off, increasing the gate edge field The first distance is selected so that
The first drain bias is about 2-5 times greater than the absolute value of the available gate swing amplitude above the threshold.
Semiconductor device. A fourth passivation layer disposed above the second metal pattern; and
Further comprising a shield wrap, defined by a third metal pattern, disposed on the fourth passivation layer.
The third metal pattern is electrically connected to the source electrode and at a fourth distance from the second extending portion of the drain electrode adjacent to the third metal pattern. It extends laterally above most of the laterally conductive channels so that the metal pattern has ends.
The semiconductor device of claim 17. The end-to-end distance between the third metal pattern and the second extending portion of the drain electrode is 2 to 6 micrometers; and the thickness of the fourth passivation layer. Is 0.5 to 2 micrometers,
The semiconductor device of claim 18. The second distance is a second drain bias that is greater than the peaking bias of the gate end electric field provided by the gate field plate when part of the laterally conductive channel below the gate electrode is in a pinch-off state. However, it is sufficient to bring about a plateau to the end electric field of the gate field plate.
The semiconductor device of請Motomeko 17. The second drain bias is about 2.5 to 10 times greater than the first drain bias.
The semiconductor device of claim 20. Lateral depletion spread below the second metal pattern, at least before the laterally conductive channel is vertically pinched off below the end of the second metal pattern closest to the end of the drain electrode. The second distance is long enough so that the existing portion never reaches the end of the second metal pattern.
The semiconductor device of claim 17. The first distance is 1.5 to 3.5 micrometers;
The second distance is 2.5 to 7.5 micrometers;
The third distance is 2 to 6 micrometers;
The end-to-end distance between the gate electrode and the drain electrode is 8 to 26 micrometers; and the thickness of the third passivation layer is 0.35 to 0.75 micrometers. Is,
The semiconductor device of claim 17.