E-HEMT device preparation method and E-HEMT device

Abstract

The invention provides an E-HEMT device preparation method, which comprises the steps of S1, providing a substrate, and forming a buffer layer on the upper side of the substrate; s2, sequentially arranging a channel layer and a barrier layer on the upper side of the buffer layer; s3, arranging a P-type doped layer on the upper side of the barrier layer; s4, forming a stress layer and a first electrode on the upper side of the P-type doped layer; and S5, preparing a second electrode and a third electrode in the first region. The invention further discloses the E-HEMT device corresponding to the preparation method of the E-HEMT device. According to the E-HEMT device provided by the invention, the turn-on voltage is remarkably improved, the driving stability of the device is good, the preparation steps of the preparation method of the E-HEMT device are simple, and the popularization of the E-HEMT device is facilitated.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor devices, and in particular relates to an E-HEMT device preparation method and an E-HEMT device. Background Art

[0002] Semiconductor devices made of wide bandgap semiconductor material gallium nitride (GaN) have become one of the most important representatives of power electronic devices due to their excellent characteristics of high electron mobility, high saturated electron drift rate and high critical breakdown electric field. Among them, HEMT (High electron mobility transistor) devices have better conductivity when there is no external gate voltage due to the high electron concentration in their channels, and are usually called depletion-mode high electron mobility transistors (D-HEMT). In practical applications, such devices usually require the introduction of additional drive circuits to achieve the normally-off state of the device. E-HEMT (enhancement-mode high electron mobility transistor) achieves the depletion of electrons in the channel by introducing a P-type doping layer or electron blocking layer at the gate, thereby achieving the normally-off characteristic. It is non-conductive when there is no external gate voltage, which greatly simplifies the drive circuit structure.

[0003] However, the preparation of the P-type doped layer is mainly achieved by doping magnesium ions into the nitride semiconductor, but the actual activation of magnesium ion-doped gallium nitride generates a limited concentration of holes, resulting in the gate turn-on voltage of the E-HEMT device in the prior art not exceeding 2V, and the average gate turn-on voltage is only about 1.7V. Too low a gate turn-on voltage will seriously weaken the reliability of the E-HEMT device, and the device is prone to uncontrolled turn-on. In response to the above problems, the patent TWI692111B increases the turn-on voltage of the device by forming a Schottky barrier between the gate and the gallium nitride layer, but the preparation of the device is complex, the manufacturing cost is high, and it is difficult to promote. In addition, the prior art also uses magnesium ion doping and activation processes to address the problem of too low turn-on voltage of the E-HEMT device, but these process steps are complicated, difficult to implement, and the effects are not ideal.

[0004] Based on the above, this application provides a technical solution to solve the above technical problems. Summary of the invention

[0005] In view of the low turn-on voltage and poor device stability of the E-HEMT device in the prior art, the present invention provides a method for preparing an E-HEMT device, comprising:

[0006] Step S1, providing a substrate, and forming a buffer layer on the upper side of the substrate;

[0007] Step S2, sequentially disposing a channel layer and a barrier layer on the upper side of the buffer layer;

[0008] Step S3, providing a P-type doping layer on the upper side of the barrier layer;

[0009] Step S4, forming a stress layer and a first electrode on the upper side of the P-type doping layer;

[0010] Step S5, preparing a second electrode and a third electrode in the first region.

[0011] In a specific embodiment of the present invention, the E-HEMT device includes a first region and a second region, the second region is a region vertically projected by the first electrode above the barrier layer, and the first region is a portion of the barrier layer outside the second region.

[0012] In a specific embodiment of the present invention, before executing step S5, step A is also included: etching and removing the stress layer portion and the P-type doped layer portion in the first region, wherein the P-type doped layer is a P-GaN layer; the P-GaN layer is obtained by injecting P-type doped ions into the nitride semiconductor layer.

[0013] In a specific embodiment of the present invention, the first electrode is a gate G, the second electrode is a source S, and the third electrode is a drain D. The source S and the drain D are both disposed in a first region on the barrier layer.

[0014] In a specific embodiment of the present invention, step S1 specifically includes: forming a nucleation layer on the substrate, and forming a buffer layer on the upper side of the nucleation layer.

[0015] In a specific embodiment of the present invention, the stress layer is made of a material that can produce a piezoelectric polarization effect on III-V nitride.

[0016] In a specific embodiment of the present invention, the stress layer is prepared from at least one of titanium nitride TiN, gallium nitride GaN, aluminum nitride AlN, and aluminum gallium nitride AlGaN.

[0017] In a specific embodiment of the present invention, the first electrode is a Schottky electrode, and the second electrode and the third electrode are ohmic electrodes.

[0018] In a specific embodiment of the present invention, the barrier layer is prepared from at least one of aluminum nitride AlN and aluminum gallium nitride AlGaN.

[0019] The present invention further provides an E-HEMT device, which is prepared by using any of the above-mentioned methods for preparing an E-HEMT device, wherein the E-HEMT device comprises, from bottom to top:

[0020] Substrate, buffer layer, channel layer, barrier layer, P-type doping layer, stress layer, first electrode;

[0021] The upper side of the barrier layer also includes a second electrode and a third electrode.

[0022] The present invention can bring at least one of the following beneficial effects: The present invention provides a method for preparing an E-HEMT device, comprising: first forming an E-HEMT device structure on a substrate, which sequentially comprises a nucleation layer, a buffer layer, a channel layer, a barrier layer, and a P-type doping layer, then forming a stress layer and a first electrode on the upper side of the P-type doping layer, etching and removing the stress layer and the P-type doping layer in the first region, and then preparing a second electrode and a third electrode in the first region above the barrier layer. In the preparation method, a stress layer is deposited on the upper side of the P-type doping layer, and the stress layer generates a negative piezoelectric potential on the surface of the P-type doping layer through a piezoelectric polarization effect, thereby improving the E-HEMT device structure. At the same time, the setting of the stress layer also effectively reduces the activation energy and defect formation energy generated by the addition of P-type doping ions into the nitride semiconductor during the preparation of the P-type doping layer, thereby increasing the hole concentration without affecting the channel layer. This effect, combined with the piezoelectric polarization effect, can greatly increase the turn-on voltage of the E-HEMT device and significantly optimize the driving stability of the E-HEMT device. At the same time, the E-HEMT device and the preparation method provided by the present invention minimize the impact of increasing the turn-on voltage of the E-HEMT device on the on-resistance, and achieve an excellent balance between the turn-on voltage and the on-resistance. In addition, the preparation method has simple preparation steps and low cost, which is also conducive to the subsequent promotion and application of E-HEMT devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The preferred implementation scheme will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and their implementation methods.

[0024] Figure 1 A schematic diagram of the steps of a method for preparing an E-HEMT device in Embodiment 1 of the present invention;

[0025] Figure 2 The device morphology is obtained according to steps S1 to S4 of the preparation method in Example 1 of the present invention;

[0026] Figure 3 The device morphology is obtained according to step A of the preparation method in Example 1 of the present invention;

[0027] Figure 4 Schematic diagram of the structure of the stress layer and the effective stress layer prepared by the preparation method in Example 1 of the present invention;

[0028] Figure 5This is the E-HEMT device structure obtained according to the preparation method in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] Various aspects of the present invention are described in further detail below.

[0030] Unless otherwise defined or indicated, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the present invention.

[0031] The following is an explanation of the terms.

[0032] Unless otherwise clearly specified and limited, the "or" mentioned in the present invention includes the relationship of "and". The "and" is equivalent to the Boolean logic operator "AND", the "or" is equivalent to the Boolean logic operator "OR", and "AND" is a subset of "OR".

[0033] It is to be understood that although the terms "first", "second", etc. may be used herein to describe different elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Therefore, the first element may be referred to as the second element without departing from the teachings of the present invention.

[0034] In the present invention, the terms "comprising", "including" or "comprising" indicate that various components can be applied together in the mixture or composition of the present invention. Therefore, the term "consisting mainly of..." is included in the terms "comprising", "including" or "comprising".

[0035] Unless otherwise clearly specified and limited, the terms "connected", "connected" and "connection" in the present invention should be understood in a broad sense, for example, it can be a fixed connection, or it can be connected through an intermediary medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] For example, if an element (or component) is referred to as being on, coupled to, or connected to another element, the element may be directly formed on, coupled to, or connected to the other element, or there may be one or more intervening elements between them. In contrast, if the expressions "directly on," "directly coupled to," and "directly connected to" are used herein, then no intervening elements are indicated. Other words used to describe the relationship between elements should be similarly interpreted, such as "between" and "directly between," "attached" and "directly attached," "adjacent" and "directly adjacent," and the like.

[0037] It should also be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings. The words "inner" and "outer" used refer to directions toward or away from the geometric center of a particular component, respectively. It can be understood that these terms are used here to describe the relationship of one element, layer or region relative to another element, layer or region as shown in the drawings. In addition to the orientations described in the drawings, these terms should also include other orientations of the device.

[0038] Other aspects of the present invention will be apparent to those skilled in the art in view of the disclosure herein.

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0040] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show the components related to the present application and are not drawn according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the component layout may also be more complicated. For example, the thickness of the components in the drawings may be exaggerated for the sake of clarity.

[0041] Embodiment 1

[0042] For the scenario where the E-HEMT device has a low turn-on voltage and poor device stability in the prior art, see Figure 1 The present invention provides a method for preparing an E-HEMT device, comprising:

[0043] Step S1, providing a substrate 1, and forming a buffer layer 3 on the upper side of the substrate;

[0044] Step S2, sequentially disposing a channel layer 4 and a barrier layer 5 on the upper side of the buffer layer;

[0045] Step S3, providing a P-type doping layer 6 on the upper side of the barrier layer 5;

[0046] Step S4, forming a stress layer 7 and a first electrode on the upper side of the P-type doping layer;

[0047] Step S5, preparing a second electrode and a third electrode in the first region.

[0048] In a preferred embodiment of the present invention, before executing step S5, step A is further included, and the E-HEMT device that has not been processed by step A is as follows: Figure 2 As shown, the morphology of the E-HEMT device after step A is as follows Figure 3 As shown: a portion of the stress layer 7 and a portion of the P-type doped layer 6 in the first region are etched away, the P-type doped layer 6 is a P-GaN layer; the P-GaN layer is obtained by injecting P-type doped ions into the nitride semiconductor layer, and preferably, the thickness of the P-GaN layer is 100 nm.

[0049] It should be understood that Figure 2 , Figure 3 It is only a schematic diagram of the E-HEMT device structure. The thicknesses of the substrate 1, the nucleation layer 2, the buffer layer 3, the channel layer 4, the barrier layer 5, the P-type doping layer 6, and the stress layer 7 do not represent the actual thicknesses of the various structures in the E-HEMT device.

[0050] More preferably, the nitride semiconductor is gallium nitride GaN, the P-type doping ions are magnesium ions Mg, and the doping concentration of the P-type doping ions is preferably 1×10 18 cm -3 ~3×10 18 cm -3 , where the magnesium ion Mg doping concentration is 2×10 18 cm -3 The preparation effect is best.

[0051] Preferably, Figure 2 , Figure 3 As shown in the red dotted area X and the blue dotted area Y, the E-HEMT device includes a first area X and a second area Y, the second area Y is an area where the first electrode is vertically projected above the barrier layer, and the first area X is a portion of the barrier layer other than the second area Y.

[0052] Specifically, the substrate 1 is preferably made of at least one material selected from GaN, Si, SiC, and sapphire, and has a thickness of preferably 200 to 500 μm. More preferably, the substrate 1 is a gallium nitride wafer substrate with a thickness of 300 μm.

[0053] In a preferred embodiment of the present invention, the first electrode is a gate G, the second electrode is a source S, and the third electrode is a drain D. The source S and the drain D are both disposed in a first region on the barrier layer.

[0054] In a preferred embodiment of the present invention, step S1 specifically includes: forming a nucleation layer 2 on the substrate 1, and forming a buffer layer 3 on the upper side of the nucleation layer 2. Preferably, the nucleation layer 2 is composed of AlN or AlGaN, and the thickness is preferably 1-5 μm, and the buffer layer 3 is composed of at least one of AlN, AlGaN, and GaN, and the thickness is preferably 1-5 μm. Based on the comprehensive consideration of the volume and performance of the semiconductor device, the thickness of the nucleation layer 2 is preferably 1-3 μm, and the thickness of the buffer layer 3 is preferably 2-4 μm.

[0055] In a preferred embodiment, the channel layer 4 is composed of gallium nitride, and includes a two-dimensional electron gas (2DEG). The channel layer 4 has a thickness of 1 to 4 μm. Preferably, the channel layer 4 has a thickness of 2 μm.

[0056] In a preferred embodiment of the present invention, the stress layer 7 is made of a material that can produce a piezoelectric polarization effect on III-V nitrides. For example, the stress layer 7 is made of at least one of titanium nitride TiN, gallium nitride GaN, aluminum nitride AlN, and aluminum gallium nitride AlGaN.

[0057] In a preferred embodiment of the present invention, the first electrode is a Schottky electrode, and the second electrode and the third electrode are ohmic electrodes. It should be understood that the Schottky electrode is composed of metal and semiconductor materials, and the semiconductor material in the Schottky electrode makes it unidirectionally conductive, and the ohmic electrode is a metal electrode.

[0058] More preferably, the first electrode is made of TiN / Al or Ni / Au material; the second electrode and the third electrode are made of Ti / Al / Ti / TiN or Ti / Al / Ni / Au material.

[0059] In a preferred embodiment of the present invention, the barrier layer 5 is made of at least one of aluminum nitride AlN and aluminum gallium nitride AlGaN, and the thickness of the barrier layer 5 is 10 to 30 nm. Preferably, the thickness of the barrier layer 5 is 20 nm.

[0060] It should be understood that if Figure 4As shown, the thickness of the upper portion of the P-type doped layer is the effective stress thickness 6A (see Figure 4 The green rectangle in the middle indicates the thickness range in which the stress layer 7 can exert stress modulation effect on the P-type doped layer 6. As shown in Table 1, the thickness range has a significant effect on the size of the piezoelectric potential, wherein the thickness of the effective stress action thickness 6A does not exceed the total thickness of the P-type doped layer 6.

[0061] It should be understood that Figure 4 The dimensions of the gate G, the stress layer 7, the effective stress thickness 6A, and the P-type doping layer 6 are shown for illustration only. Their thicknesses do not represent the actual thicknesses of the various structures in the E-HEMT device and should not be construed as limiting the scope of protection of the present invention.

[0062] In an application example, actual application parameters of an E-HEMT device prepared according to the E-HEMT device preparation method provided in Example 1 are shown in Table 1.

[0063]

[0064]

[0065] Table 1 Actual application parameters of E-HEMT devices

[0066] Wherein, the width and length represent the size of a typical P-GaN layer, wherein the length refers to the direction of 2DEG flow in the channel layer 4. The effective stress thickness 6A represents the thickness range of the stress effect of the stress layer 7 on the P-GaN layer, and the tensile stress represents the form of stress effect of the stress layer 7 on the P-GaN layer. The polarization charge represents the polarization charge density generated by the stress effect on the surface of the P-GaN layer, and the piezoelectric potential represents the voltage formed on the surface of the P-GaN layer by the stress effect applied by the stress layer 7. It should be understood that in order to achieve the actual required effective stress thickness 6A, the stress layer 7 can adjust the corresponding material and thickness accordingly. Increasing the thickness of the stress layer 7 or changing the corresponding material properties will increase the effective stress thickness 6A, thereby more significantly increasing the piezoelectric potential.

[0067] It can be seen that the piezoelectric potential on the surface of the P-GaN layer is negative under the action of stress, which indicates that the external turn-on voltage must first offset this part of the negative piezoelectric potential before the E-HEMT device can be turned on, that is, the turn-on voltage of the device is improved compared with the case without negative piezoelectric potential; in addition, the stress layer 7 also increases the hole activation concentration generated by the magnesium ions doped when preparing the P-GaN layer, which can also increase the turn-on voltage of the E-HEMT device.

[0068] Embodiment 2

[0069] The present invention also provides an E-HEMT device, which is prepared by the E-HEMT device preparation method described in Example 1, and the E-HEMT device has a structure as shown in Figure 5 As shown, the E-HEMT device includes from bottom to top:

[0070] Substrate 1, buffer layer 3, channel layer 4, barrier layer 5, P-type doping layer 6, stress layer 7, first electrode;

[0071] The barrier layer 5 further includes a second electrode and a third electrode on its upper side.

[0072] It should be understood that Figure 5 It is only a schematic diagram of the E-HEMT device structure. The thicknesses of the substrate 1, the nucleation layer 2, the buffer layer 3, the channel layer 4, the barrier layer 5, the P-type doping layer 6, and the stress layer 7 do not represent the actual thicknesses of the various structures in the E-HEMT device.

[0073] In summary, the present invention has achieved the following effects:

[0074] Embodiment 1 of the present invention provides a method for preparing an E-HEMT device, comprising: first forming an E-HEMT device structure on a substrate, the structure comprising a nucleation layer, a buffer layer, a channel layer, a barrier layer, and a P-type doping layer in sequence, then forming a stress layer and a first electrode on the upper side of the P-type doping layer, etching and removing the stress layer and the P-type doping layer in the first region, and then preparing a second electrode and a third electrode in the first region above the barrier layer. In the preparation method, by depositing a stress layer on the upper side of the P-type doping layer, the stress layer generates a negative piezoelectric potential on the surface of the P-type doping layer through a piezoelectric polarization effect, thereby increasing the turn-on voltage of the E-HEMT device; and The setting of the stress layer also effectively reduces the activation energy and defect formation energy generated by doping P-type doping ions into the nitrogen-based semiconductor during the preparation of the P-type doping layer, thereby increasing the hole concentration without affecting the channel layer. This effect, combined with the piezoelectric polarization effect, can greatly increase the turn-on voltage of the E-HEMT device and significantly optimize the driving stability of the E-HEMT device. At the same time, the E-HEMT device and the preparation method thereof provided in the first and second embodiments of the present invention minimize the influence of increasing the turn-on voltage of the E-HEMT device on the on-resistance, and achieve an excellent balance between the turn-on voltage and the on-resistance.

[0075] In addition, the preparation method has simple preparation steps and low cost, which is also conducive to the subsequent promotion and application of E-HEMT devices.

[0076] Based on this application, it should be understood by those skilled in the art that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0077] It should be noted that the above embodiments can be freely combined as needed. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention.

[0078] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference separately. In addition, it should be understood that after reading the above content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing an E-HEMT device, characterized in that: include: Step S1, providing a substrate, and forming a buffer layer on the upper side of the substrate; Step S2, sequentially disposing a channel layer and a barrier layer on the upper side of the buffer layer; Step S3, providing a P-type doping layer on the upper side of the barrier layer; Step S4, forming a stress layer and a first electrode on the upper side of the P-type doping layer; Step S5, preparing a second electrode and a third electrode in the first region.

2. The method for preparing an E-HEMT device according to claim 1, characterized in that: The E-HEMT device includes a first region and a second region, wherein the second region is a region on the barrier layer where the first electrode is vertically projected, and the first region is a portion of the barrier layer outside the second region.

3. The method for preparing an E-HEMT device according to claim 2, characterized in that: Before executing step S5, the method further includes: etching away a stress layer portion and a P-type doped layer portion in the first region, wherein the P-type doped layer is a P-GaN layer; and the P-GaN layer is obtained by injecting P-type doped ions into the nitride semiconductor layer.

4. A method for preparing an E-HEMT device according to any one of claims 1 to 3, characterized in that: The first electrode is a gate G, the second electrode is a source S, and the third electrode is a drain D. The source S and the drain D are both disposed in a first region on the barrier layer.

5. The method for preparing an E-HEMT device according to claim 3, characterized in that: Step S1 specifically includes: forming a nucleation layer on the substrate, and forming a buffer layer on the upper side of the nucleation layer.

6. A method for preparing an E-HEMT device according to any one of claims 1 to 3, characterized in that: The stress layer is made of a material that can produce a piezoelectric polarization effect on III-V nitride.

7. The method for preparing an E-HEMT device according to claim 6, characterized in that: The stress layer is prepared from at least one of titanium nitride TiN, gallium nitride GaN, aluminum nitride AlN, and aluminum gallium nitride AlGaN.

8. A method for preparing an E-HEMT device according to any one of claims 1 to 3, characterized in that: The first electrode is a Schottky electrode, and the second electrode and the third electrode are ohmic electrodes.

9. A method for preparing an E-HEMT device according to any one of claims 1 to 3, characterized in that: The barrier layer is prepared from at least one of aluminum nitride AlN and aluminum gallium nitride AlGaN.

10. An E-HEMT device, characterized in that: The E-HEMT device is prepared by the method for preparing the E-HEMT device according to any one of claims 1 to 9, wherein the E-HEMT device comprises, from bottom to top: Substrate, buffer layer, channel layer, barrier layer, P-type doping layer, stress layer, first electrode; The upper side of the barrier layer also includes a second electrode and a third electrode.

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