Stacked III-V semiconductor diode

Abstract

To provide a layered III-V group semiconductor diode containing, or consisting of, GaAs with a highly n-doped cathode layer, a highly p-doped anode layer, and a drift region positioned between the cathode layer and the anode layer.SOLUTION: A layered III-V group semiconductor diode includes: a highly n-doped cathode layer 16; highly p-doped anode layer 12; and a drift region 14 located between the cathode layer and the anode layer and having a dopant concentration of at most to 8×1015 cm-3 and a layer thickness of at least 10 μm. The cathode layer has a delta layer division 16.1 with a layer thickness Dk ranging from 0.1 μm to 2 μm and a dopant concentration of at least 1×1019 cm-3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminated III-V semiconductor diode including or consisting of GaAs, having a cathode layer highly doped with n, an anode layer highly doped with p, and a drift region disposed between the cathode layer and the anode layer.

Background Art

[0002] A p + -n-n + Structured high-voltage-resistant semiconductor diode is known from pages 8 and 9 of "GaAs Power Devices" by German Ashkinazi, ISBN 965-7094-19-4.

[0003] Other laminated III-V semiconductor diodes are known from European Patent No. 3321971 and European Patent No. 3321970, and the semiconductor diode has an additional intermediate layer between the drift region and the cathode or anode.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Based on such a background, the problem to be solved by the present invention is to provide a device that develops the prior art.

Means for Solving the Problems

[0005] This problem is solved by a laminated III-V semiconductor diode having the characteristic configuration of claim 1 of the claims. Advantageous embodiments of the present invention are the subject of the dependent claims.

[0006] According to the subject of the present invention, a laminated III-V semiconductor diode includes or consists of GaAs, having a cathode layer highly doped with n and an anode layer highly doped with p.

[0007] A drift region having a dopant concentration of up to 8×10 15 cm -3 and a layer thickness of at least 10 μm is disposed between the cathode layer and the anode layer. Preferably, the overall layer thickness of the drift region is up to 50 μm or up to 100 μm.

[0008] The cathode layer has a first section and a second section.

[0009] The first section is configured as a delta layer section having a layer thickness of from 0.1 μm to 1 μm or from 0.1 μm to 2 μm.

[0010] The delta layer section has a dopant concentration of at least 1×10 19 cm -3 or at least 2×10 19 cm -3 .

[0011] It is obvious that all semiconductor layers of a semiconductor diode made of GaAs or containing GaAs, namely, in particular the cathode layer, the anode layer and the drift region, are each made of GaAs or at least contain GaAs. In other words, each semiconductor layer of a III-V semiconductor diode has at least the elements Ga and As.

[0012] Furthermore, it is obvious that a pn junction is formed in the drift region.

[0013] Note that the semiconductor layers of the semiconductor diode are configured in a stacked manner so as to overlap. Preferably, the semiconductor layers have the same area. Preferably, one of the plurality of semiconductor layers is configured as a substrate layer or includes a substrate layer. In one development form, the substrate layer has an area larger than that of the stack of semiconductor layers disposed on the substrate layer.

[0014] The substrate layer preferably has a thickness of from 50 μm to 120 μm or from 50 μm to 250 μm. In one development form, in the case of p-doping, the substrate layer has a concentration in the range of from 1×10 17 cm -3 to 2×10 18 cm -3 or up to 8×10 18 cm -3 at most.

[0015] The semiconductor layers are preferably produced by epitaxial growth overlapping one another. Particularly preferably, the cathode layer or the anode layer is constituted by a substrate layer on which all the other semiconductor layers are sequentially epitaxially grown. Alternatively, the layers are joined using wafer bonding.

[0016] Furthermore, it is self-evident that the semiconductor diode preferably has another layer made of another material, in particular a connection contact layer made of metal.

[0017] Furthermore, it should be noted that the term anode is used synonymously with the term anode layer, and the term cathode is used synonymously with the term cathode layer, respectively.

[0018] The connection contact layer consists, for example, entirely or partly of metal, for example gold, or from a metal alloy, and is produced, for example, using electron beam evaporation or using sputtering.

[0019] In order to constitute an electrical contact connection with as low a resistance as possible and to keep the series resistance or the loss output of the semiconductor diode as small as possible, the regions of the cathode layer and the anode layer in contact with the connection contact layer preferably have a higher dopant concentration than the other parts of the cathode layer and the anode layer, respectively.

[0020] At least, it is made possible via a relatively small thickness, that is to say preferably less than 1 μm, to achieve a very high concentration of doping, in particular at least 1×10 19 cm-3 It is to fabricate the doping with good layer quality. Regarding this, suitable dopants for the cathode layer in particular are, for example, tellurium or selenium.

[0021] Correspondingly, the layer thickness of the second section of the cathode layer substantially follows that of the minority charge carriers, i.e., the hole lifetime or penetration depth. Typically, a layer thickness of the second layer from several hundred nanometers up to a maximum of 2 μm is sufficient.

[0022] In other words, the thickness of the second section of the cathode layer is preferably the same as the free path length of the minority charge carriers, i.e., holes, in the cathode.

[0023] Furthermore, the delta layer section forms so-called a barrier for the minority charge carriers and reduces the contact resistance. In particular, the switch-off operation is improved by the delta layer section, and thereby the switching operation of the diode is improved.

[0024] What is shown by tests is that the emitter efficiency, i.e., the efficiency of the cathode, can be improved from the combination of a thin but highly doped delta layer section and the second section of the cathode layer doped at a lower concentration.

[0025] In combination with a drift region doped at a low concentration, the diode can be fabricated with a particularly high blocking voltage exceeding 1100 V, or even exceeding 1200 V, a small on-resistance, and a particularly small capacitance per unit area.

[0026] In one embodiment, the cathode layer has a second layer section having a dopant concentration lower than that of the delta layer section, whereby the delta layer section supplements the typical cathode layer by a so-called delta-doping peak.

[0027] The delta layer section preferably has a bond by material bonding with a second connection contact made of metal. In other words, the metal connection contact is disposed on the upper surface of the cathode layer.

[0028] A first connection contact made of metal is provided on the lower surface of the anode layer. Preferably, the two metal connection contacts cover the anode layer and / or the cathode layer in the central region, or almost completely, or completely, in order to achieve a low connection resistance. Even in the case of complete coverage, it is obvious that the peripheral edge portion surrounding it is not metallized in order to enhance the certainty of the process.

[0029] In one development form, the second layer section of the cathode layer has a lower dopant concentration than the delta layer section. Preferably, the second layer section of the cathode layer has a layer thickness D K2 greater than that of the delta layer section.

[0030] Preferably, the second layer section of the cathode layer has a thickness ranging from at least 0.5 μm to a maximum of 1.5 μm, or from at least 0.5 μm to a maximum of 2.5 μm, or from at least 0.5 μm to a maximum of 5 μm.

[0031] Note that the terms "doping" and "dopant concentration" are used synonymously. Furthermore, note that the change in doping between the delta layer section and the second section of the cathode layer is preferably made abruptly. In other words, the doping preferably changes within a thickness range less than 0.1 μm or less than 0.05 μm.

[0032] The dopant concentration of the second layer section of the cathode layer is less than 1×10 19 cm -3 . Preferably, the dopant concentration of the second layer section of the cathode layer is 1×10 18 cm -3 or 2×10 18 cm -3 or 5×10 18 cm-3 exceeds.

[0033] In one development form, the cathode layer has a transition layer section, the transition layer section is arranged between the second section of the cathode layer and the drift region, and has a layer thickness of at least 3 μm, a doping less than that of the second section, a doping higher than that of the drift region, and a concentration profile of the doping that is convex or concave or linear or stepped descending in the direction of the drift region.

[0034] In another embodiment, the delta layer section has Te and / or Se as dopants.

[0035] Hereinafter, the present invention will be described in detail with reference to the drawings. Here, the same reference numerals are assigned to the same parts. The illustrated embodiments are greatly simplified, that is, the intervals and the lengths in the horizontal and vertical directions are not to scale, and unless otherwise specified, the derivable geometric relationships do not have each other either.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0037] The figure of FIG. 1 shows a first embodiment of a laminated III-V semiconductor diode 10 having or consisting of GaAs. The overall thickness D A The highly doped p-doped substrate layer having D forms the anode layer 12, and the drift region 14 having the overall thickness D is disposed in the anode layer 12 D Following the drift region 14, a cathode layer 16 having a layer thickness D doped highly with n is disposed K .

[0038] It is obvious that a pn junction is formed in the drift region 14.

[0039] The cathode layer 16 has a first section 16.1 and a second section 16.2.

[0040] The first section 16.1 of the cathode layer 16 is configured as a delta layer section having a very high dopant concentration of at least 1×10 19 cm -3 or at least 2×10 19 cm -3 , and a small layer thickness D ranging from 0.1 μm to 1 μm, or from 0.1 μm to a maximum of 2 μm. K1 .

[0041] The second layer section 16.2 has a dopant concentration lower than that of the delta layer section 16.1 and a larger layer thickness D K2 .

[0042] The second layer section 16.2 of the cathode layer 16 has a thickness in the range of 0.5 μm to 1.5 μm, or in the range of 0.5 μm to 2.5 μm, or in the range of 0.5 μm to 5 μm.

[0043] The dopant concentration of the second layer section 16.2 is below 1×10 19 cm -3 . The dopant concentration of the second layer section 16.2 is preferably 1×10 18 cm -3 or 2×10 18 cm-3 or 5×10 18 cm -3 and exceeds it.

[0044] On the lower surface of the anode layer 12, a metal connection contact M1 is disposed, or on the upper surface of the cathode layer 16, a metal connection contact M2 is disposed.

[0045] The two metal connection contacts M1, M2 preferably substantially completely cover the anode layer 12 and / or the cathode layer 16 in order to achieve a low connection resistance. The delta layer section 16.1 preferably also has a bond by material bonding with the metal connection contact M2.

[0046] In the diagram of FIG. 2, the dopant concentration profile along the thickness of the stacked III-V semiconductor diode 10 is shown and drawn in relation to FIG. 1.

[0047] Plotted is the dopant concentration D for the position x along the stack of the III-V semiconductor diode 10.

[0048] The dopant concentration profile is respectively configured to be constant over the respective layer thicknesses D K2 and D K1 of the two sections 16.2 and 16.1 of the cathode layer 16, whereby a dopant concentration jump is formed between the second layer section 16.2 and the delta layer section.

[0049] Subsequently, the dopant concentration jumps down to a very low level in the range of at most 8×10 15 cm -3 in the drift region 14. At the transition from the drift region 14 to the anode layer, the dopant concentration jumps up to a certain high level of the p-dopant concentration.

[0050] The dopant concentration along the anode 12 is constant, and the height of the dopant concentration is lower than the dopant concentration of the second region 16.2 of the cathode 16.

[0051] In the illustrated embodiment, the drift region has a low and substantially constant dopant concentration. The doping along the overall layer thickness varies between an n-dopant and a p-dopant, whereby a p-n junction is formed in the drift region 14.

[0052] In the embodiment shown in FIG. 3, the metallic connection contacts M1 and M2 are configured as a plane.

[0053] The cathode layer 16 has a transition layer section 16.3 in addition to a first section 16.1 and a second section 16.2. The transition layer section 16.3 has a layer thickness D of at least 3 μm and, for example, at most 10 μm or at most 5 μm. K3 has.

[0054] The transition layer section 16.3 of the cathode layer 16 has less doping than the second section 16.2 of the cathode layer 16 and higher doping than the doping of the drift region 14.

[0055] The concentration profile of the doping descending in the direction of the drift region 14 within the transition layer section 16.3 is configured convex or concave or linear or stepped.

[0056] In the embodiment of FIG. 4, the two metallic connection layers M1, M2 each cover only the central part of the anode or cathode. The transition layer section 16.3 is not configured, whereby the second section 16.2 of the cathode directly follows the drift region 14.

[0057] In the embodiment shown in FIG. 5, the cathode layer 16 has a transition layer section 16.3 in addition to the second layer section 16.2.

[0058] Between the drift region 14 and the second section 12.2 of the anode layer 12, a p-doped transition layer section 12.3 is formed as part of the anode layer 12.

[0059] The dopant concentration in the transition layer section 12.3 of the anode increases in the direction of the second section 12.2 of the anode layer 12 along the layer thickness of the transition layer section 12.3. The increase in doping is configured to be concave or convex or linear or stepped.

[0060] In the diagram of FIG. 6, the dopant concentration profile for the embodiment described in relation to FIG. 5 is depicted. Hereinafter, only the differences from the embodiment of FIG. 2 will be described.

[0061] The delta layer section 16.1 of the cathode layer 16 is disposed on the side of the second layer section 16.2 facing away from the drift region 14, whereby the dopant concentration along the cathode layer jumps downwards in the direction of the drift region 14.

[0062] Here too, a transition layer section 16.3 is formed as part of the cathode layer 16 between the second section 16.2 of the cathode layer 16 and the drift region 14.

[0063] The dopant concentration in the transition layer section 16.3 of the cathode layer 16 decreases in the direction of the drift region 14 in the subsequent course.

[0064] A p-doped transition layer section 12.3 is formed as part of the anode layer 12 between the drift region 14 and the second section 12.2 of the anode layer 12. The dopant concentration in the transition layer section 12.3 of the anode layer 12 increases in the direction of the second section 12.2 of the anode layer 12 in the subsequent course.

Claims

1. A laminated III-V semiconductor diode (10) comprising or consisting of GaAs, wherein the laminated III-V semiconductor diode (10) comprises: - A cathode layer (16) highly doped with n-type dopants; - An anode layer (12) highly doped with p-type dopants; ・Disposed between the cathode layer (16) and the anode layer (12), having a dopant concentration of up to 8×10 １５ cm －３ , and a layer thickness (D Ｄ ) of at least 10 μm and up to 80 μm, a drift region (14); In the laminated III-V semiconductor diode (10) having: - The cathode layer (16) has a first section (16.1) and a second section (16.2); - The first section (16.1) is configured as a delta layer section having a layer thickness (D Ｋ１ ) ranging from 0.1 μm to 2 μm, and has a dopant concentration of at least 1 × 10 １９ cm-3, - The second section (16.2) has a lower dopant concentration than the first section (16.1), and the dopant concentration of the second section (16.2) is higher than 1×10 １８ cm －３ and the second section (16.2) is disposed between the first section (16.1) and the drift region (14). - In the drift region (14), the doping varies between an n-dopant and a p-dopant, thereby forming a p-n junction; A laminated III-V semiconductor diode (10).

2. The delta layer section (16.1) is in material contact with a metallic cathode contact connection layer (M2). The laminated III-V semiconductor diode (10) according to Claim 1.

3. The change in doping between the delta layer section (16.1) and the second section (16.2) of the cathode layer occurs abruptly. The laminated III-V semiconductor diode (10) according to Claim 1 or 2.

4. The second section (16.2) of the cathode layer (16) has a dopant concentration lower than 1×10 １９ cm －３ and higher than 2×10 １８ cm －３ . The laminated III-V semiconductor diode (10) according to any one of Claims 1 to 3.

5. The second section (16.2) of the cathode layer (16) has a layer thickness (D Ｋ２ ) ranging from 0.5 µm to 1.5 µm The laminated III-V semiconductor diode (10) according to any one of Claims 1 to 4.

6. The cathode layer (16) has a transition layer section (16.3), and the transition layer section (16.3) is disposed between the second section (16.2) and the drift region (14), and has a layer thickness (D Ｋ３ ) of at least 3 μm. The transition layer section (16.3) has a dopant concentration lower than that of the second section (16.2) and higher than that of the drift region (14), and the dopant concentration profile has a dopant concentration profile that descends convexly or concavely or linearly or stepwise in the direction of the drift region (14). The laminated III-V semiconductor diode (10) according to any one of Claims 1 to 5.

7. The anode layer (12) has a first section (12.1) and a second section (12.2) disposed between the first section (12.1) and the drift region (14), and the dopant concentration of the second section (12.2) is lower than the dopant concentration of the first section (12.1), or the dopant concentration of the second section (12.2) is equal to the dopant concentration of the first section (12.1). The laminated III-V semiconductor diode (10) according to any one of Claims 1 to 6.

8. The dopant concentration of the first section (12.1) of the anode layer (12) is at least 8×10 １７ cm －３ and at most 8×10 １８ cm －３ whereas the dopant concentration of the second section of the anode layer (12) is at least 1×10 １７ cm －３ and at most 8×10 １７ cm －３ is. The laminated III-V semiconductor diode (10) according to Claim 7.

9. The anode layer (12) has a transition section (12.3) in contact with the drift region (14), and the transition section (12.3) has a dopant concentration profile that is convex or concave or linear or stepwise decreasing in the direction of the drift region (14). The dopant concentration is higher than the dopant concentration of the p-doped drift region and lower than the dopant concentration of the second section (12.2) of the anode layer (12). The stacked III-V semiconductor diode (10) according to claim 7 or 8.

10. The second section (12.2) of the anode layer (12) has a lower doping than the second section (16.2) of the cathode layer (16). The stacked III-V semiconductor diode (10) according to any one of claims 7 to 9.

11. The delta layer section (16.1) has Te or Se as a dopant. The stacked III-V semiconductor diode (10) according to any one of claims 1 to 10.

12. The change in doping between the delta layer section (16.1) and the second section (16.2) of the cathode layer is carried out within a thickness range less than 0.1 μm. The stacked III-V semiconductor diode (10) according to claim 3.

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