Semiconductor structure and preparation method thereof

Abstract

The invention discloses a semiconductor structure and a preparation method thereof. The semiconductor structure comprises a substrate, a buffer layer, a channel layer and a barrier layer which are sequentially stacked, the buffer layer comprises doped carbon elements, the buffer layer comprises a first part and a second part which are distributed in a stacked mode, the first part is located on the side, close to the substrate, in the buffer layer, the first part points to the channel layer in the direction of the substrate, the carbon concentration in the first part is gradually increased according to the preset trend, and the carbon concentration in the second part is gradually increased according to the preset trend. The carbon concentration in the second part is gradually reduced; the buffer layer further comprises a first insertion layer, the first insertion layer is arranged between the first part and the second part, and the first insertion layer comprises an Al component. While the breakdown voltage of the device is improved, the dynamic characteristics of the device are not influenced, and the device can be prevented from electric leakage.

Description

Technical Field

[0001] The present invention relates to the technical field of power devices, and in particular, to a semiconductor structure and a preparation method thereof. Background Art

[0002] A high electron mobility transistor (HEMT) is a heterojunction field effect transistor. Taking the AlGaN / GaN HEMT structure as an example, the bandgap of AlGaN is larger than that of GaN. When they form a heterojunction, a two-dimensional electron gas (2DEG) is formed at the interface between AlGaN and GaN. Therefore, HEMT is also called a 2DEG field effect transistor.

[0003] For GaN-based HEMTs, doping carbon impurities into the region below the 2DEG can improve the pinch-off characteristics or increase the cut-off voltage. However, the electrons trapped by the charge traps formed by the impurities prevent the formation of the 2DEG, and current collapse is particularly likely to occur. Although reducing the impurity doping concentration is beneficial to suppressing current collapse, inaccurate control of the buffer layer thickness still cannot eliminate current collapse. Summary of the Invention

[0004] The present invention provides a semiconductor structure and a preparation method thereof, which can improve the breakdown voltage of the device while not affecting the dynamic characteristics of the device, avoid current collapse, and prevent device leakage.

[0005] According to one aspect of the present invention, a semiconductor structure is provided, including:

[0006] A substrate, a buffer layer, a channel layer, and a barrier layer stacked in sequence;

[0007] The buffer layer includes carbon element doping. The buffer layer includes a first part and a second part distributed in a stacked manner. The first part is located on the side of the buffer layer close to the substrate. Along the direction from the substrate to the channel layer, the carbon concentration in the first part gradually increases in a preset trend, and the carbon concentration in the second part gradually decreases;

[0008] Wherein, the buffer layer further includes a first insertion layer, and the first insertion layer is disposed between the first part and the second part. The first insertion layer includes an Al component.

[0009] Optionally, the bandgap of the first insertion layer is greater than the bandgaps of the first part and the second part.

[0010] Optionally, the first insertion layer is a group III nitride material, and the first insertion layer is a single-layer structure insertion layer or a superlattice insertion layer.

[0011] Optionally, the first insertion layer includes an Al component, and along the direction from the substrate towards the channel layer, the Al component in the first insertion layer gradually increases, gradually decreases, or first increases and then decreases; and / or, the gradual decrease of the carbon concentration in the second part includes that the carbon concentration in the second part linearly decreases or periodically decreases.

[0012] Optionally, the gradual increase of the carbon concentration in the first part according to a preset trend includes that the carbon concentration in the first part linearly increases or periodically increases.

[0013] Optionally, the buffer layer further includes at least one second insertion layer, and the second insertion layer includes an Al component; wherein,

[0014] the first part includes a plurality of first buffer sub-layers, and at least one second insertion layer is disposed between two adjacent first buffer sub-layers among the plurality of first buffer sub-layers;

[0015] and / or, the second part includes a plurality of second buffer sub-layers, and at least one second insertion layer is disposed between two adjacent second buffer sub-layers among the plurality of second buffer sub-layers.

[0016] Optionally, the carbon concentration in the plurality of first buffer sub-layers increases in a stepped manner, and the carbon concentrations in the first buffer sub-layers on both adjacent sides of the second insertion layer are different;

[0017] and / or, the carbon concentration in the plurality of second buffer sub-layers decreases in a stepped manner, and the carbon concentrations in the first buffer sub-layers on both adjacent sides of the second insertion layer are different.

[0018] Optionally, the carbon concentration in the plurality of first buffer sub-layers increases in a sawtooth manner, and the change trends of the carbon concentrations in the first buffer sub-layers on both adjacent sides of the second insertion layer are different;

[0019] and / or, the carbon concentration in the plurality of second buffer sub-layers decreases in a sawtooth manner, and the change trends of the carbon concentrations in the first buffer sub-layers on both adjacent sides of the second insertion layer are different.

[0020] Optionally, the semiconductor structure further includes:

[0021] a component inhibition layer, and the component inhibition layer is located between the buffer layer and the channel layer.

[0022] According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor structure, including:

[0023] providing a substrate, and sequentially manufacturing a buffer layer, a channel layer, and a barrier layer on one side of the substrate;

[0024] Among them, preparing the buffer layer includes doping the buffer layer with carbon. Preparing the buffer layer includes preparing a first part, a first insertion layer, and a second part that are stacked and distributed. The first part is located on the side of the buffer layer close to the substrate. Along the direction from the substrate to the channel layer, the carbon concentration in the first part gradually increases in a preset trend, and the carbon concentration in the second part gradually decreases. The first insertion layer includes an Al component.

[0025] Optionally, the carbon concentration in the first part gradually increasing in a preset trend includes the carbon concentration in the first part increasing linearly or periodically; and / or, the carbon concentration in the second part (23) gradually decreasing includes the carbon concentration in the second part (23) decreasing linearly or periodically.

[0026] Optionally, preparing the buffer layer on one side of the substrate includes:

[0027] Preparing the first part on one side of the substrate;

[0028] Preparing the first insertion layer on the side of the first part away from the substrate;

[0029] Preparing the second part on the side of the first insertion layer away from the first part.

[0030] Optionally, the first insertion layer includes an Al component. Along the direction from the substrate to the channel layer, the Al component in the first insertion layer gradually increases, gradually decreases, or first increases and then decreases.

[0031] Optionally, preparing the buffer layer further includes preparing at least one second insertion layer, and the second insertion layer includes an Al component; where

[0032] Preparing the first part includes preparing a number of first buffer sub-layers, and preparing a second insertion layer between two adjacent first buffer sub-layers among the number of first buffer sub-layers;

[0033] and / or, preparing the second part includes preparing a number of second buffer sub-layers, and preparing a second insertion layer between two adjacent second buffer sub-layers among the number of second buffer sub-layers.

[0034] Optionally, the carbon concentration in the number of first buffer sub-layers increases in a stepped manner, and the carbon concentrations in the first buffer sub-layers on both sides adjacent to the second insertion layer are different;

[0035] and / or, the carbon concentration in the number of second buffer sub-layers decreases in a stepped manner, and the carbon concentrations in the first buffer sub-layers on both sides adjacent to the second insertion layer are different.

[0036] Optionally, the carbon concentration in the number of first buffer sub-layers increases in a sawtooth manner, and the change trends of the carbon concentrations in the first buffer sub-layers on both sides adjacent to the second insertion layer are different;

[0037] And / or, the carbon concentration in several second buffer sub-layers (231) decreases in a sawtooth shape, and the change trends of the carbon concentration in the first buffer sub-layers (211) on the adjacent two sides of the second insertion layer (24) are different.

[0038] Optionally, after preparing a buffer layer on one side of the substrate, it further includes:

[0039] Preparing a component inhibition layer on the side of the buffer layer away from the substrate.

[0040] Optionally, preparing a buffer layer on one side of the substrate includes preparing a plurality of stacked structures formed by combining a first part, a first insertion layer, and a second part in sequence; the plurality of stacked structures are sequentially formed on the substrate.

[0041] The semiconductor structure provided by the technical solution of the embodiment of the present invention includes: a substrate, a buffer layer, a channel layer, and a barrier layer stacked in sequence; the buffer layer includes carbon element doping, the buffer layer includes a first part and a second part distributed in a stacked manner, the first part is located on the side of the buffer layer close to the substrate, and along the direction from the substrate to the channel layer, the carbon concentration in the first part gradually increases in a preset trend, and the carbon concentration in the second part gradually decreases. In the embodiment of the present invention, the carbon concentration in the first part of the buffer layer gradually increases in a preset trend, and the carbon concentration in the second part gradually decreases; wherein the buffer layer further includes a first insertion layer, and the first insertion layer is disposed between the first part and the second part, and the first insertion layer includes an Al component. The higher the carbon concentration, the higher the breakdown voltage of the device, which can better improve the performance of the device and prevent the device from leaking electricity; the second part close to the channel layer is set to have a gradually decreasing carbon concentration, which can improve the breakdown voltage of the device while avoiding the carbon component from doping into the channel layer, without affecting the dynamic characteristics of the device and avoiding current collapse; the setting of the first insertion layer causes a sudden change in the energy band, thereby generating a polarization effect, forming a quasi-triangular potential well at the interface, so that a large number of electrons are confined in the triangular well, which can further prevent the device from leaking electricity.

[0042] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0044] Figure 1 It is a schematic diagram of a semiconductor structure provided by Embodiment 1 of the present invention.

[0045] Figure 2 It is a graph showing the changing trend of the carbon concentration of a buffer layer provided in the first embodiment of the present invention.

[0046] Figure 3 It is another graph showing the changing trend of the carbon concentration of a buffer layer provided in the first embodiment of the present invention.

[0047] Figure 4 It is another graph showing the changing trend of the carbon concentration of a buffer layer provided in the first embodiment of the present invention.

[0048] Figure 5 It is another graph showing the changing trend of the carbon concentration of a buffer layer provided in the first embodiment of the present invention.

[0049] Figure 6 It is a schematic diagram of a semiconductor structure provided in the second embodiment of the present invention.

[0050] Figure 7 It is a schematic diagram of a semiconductor structure provided in the third embodiment of the present invention.

[0051] Figure 8 It is another schematic diagram of a semiconductor structure provided in the fourth embodiment of the present invention.

[0052] Figure 9 It is a schematic diagram of a semiconductor structure provided in the fifth embodiment of the present invention.

[0053] Figure 10 It is a flowchart for preparing a buffer layer provided in the sixth embodiment of the present invention. Detailed implementation manners

[0054] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0055] It should be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0056] Embodiment 1

[0057] An embodiment of the present invention provides a semiconductor structure. Figure 1 It is a schematic diagram of a semiconductor structure provided by Embodiment 1 of the present invention. Figure 2 It is a graph showing the change trend of the carbon concentration of a buffer layer provided by Embodiment 1 of the present invention. Refer to Figure 1 and Figure 2 , the semiconductor structure includes: a substrate 10, a buffer layer 20, a channel layer 30, and a barrier layer 40 that are sequentially stacked; the buffer layer 20 includes carbon element doping, and the buffer layer 20 includes a first portion 21 and a second portion 23 that are distributed in a stacked manner. The first portion 21 is located on the side of the buffer layer 20 close to the substrate 10. Along the direction from the substrate 10 to the channel layer 30, the carbon concentration in the first portion 21 gradually increases in a preset trend, and the carbon concentration in the second portion 23 gradually decreases.

[0058] Among them, the semiconductor structure may be a gallium nitride-based power device. Exemplarily, the semiconductor structure may be a high electron mobility transistor (HEMT). The device structure further includes a gate on the side of the barrier layer 40 away from the substrate 10, and a drain and a source on both sides of the gate respectively.

[0059] The buffer layer 20 includes carbon element doping, which can increase the resistance value of the buffer layer 20, thereby reducing the leakage of the buffer layer 20 and increasing the breakdown voltage of the device. The carbon concentration in the first part 21 of the buffer layer 20 gradually increases in a preset trend. The higher the carbon concentration, the higher the resistance of the buffer layer 20 and the higher the breakdown voltage of the device, which can better improve the performance of the device. The carbon concentration in the second part 23 gradually decreases because if the carbon concentration in the second part 23 is too high, it will reduce the two-dimensional electron gas concentration in the channel layer 30, thereby affecting the dynamic characteristics of the device. Therefore, the first part 21 of the buffer layer 20 close to the substrate 10 needs to be set so that the carbon concentration gradually increases in a preset trend, and the second part 23 close to the channel layer 30 is set so that the carbon concentration gradually decreases, which can increase the breakdown voltage of the device while not affecting the dynamic characteristics of the device, avoid current collapse, and prevent device leakage.

[0060] The semiconductor structure provided by the technical solution of the embodiment of the present invention includes: a substrate 10, a buffer layer 20, a channel layer 30, and a barrier layer 40 that are sequentially stacked. The buffer layer 20 includes carbon element doping. The buffer layer 20 includes a first part 21 and a second part 23 that are stacked and distributed. The first part 21 is located on the side of the buffer layer 20 close to the substrate 10. Along the direction from the substrate 10 to the channel layer 30, the carbon concentration in the first part 21 gradually increases in a preset trend, and the carbon concentration in the second part 23 gradually decreases. In the embodiment of the present invention, the carbon concentration in the first part 21 of the buffer layer 20 gradually increases in a preset trend, and the carbon concentration in the second part 23 gradually decreases. The higher the carbon concentration, the higher the breakdown voltage of the device, which can better improve the performance of the device and prevent device leakage. The second part 23 close to the channel layer 30 is set so that the carbon concentration gradually decreases, which can increase the breakdown voltage of the device while avoiding carbon components from doping into the channel layer and not affecting the dynamic characteristics of the device.

[0061] Optionally, referring to Figure 1 , the fact that the carbon concentration in the first part 21 gradually increases in a preset trend includes that the carbon concentration in the first part 21 increases linearly or periodically. In other embodiments, optionally, the fact that the carbon concentration in the second part 23 gradually decreases includes that the carbon concentration in the second part 23 decreases linearly or periodically.

[0062] Among them, referring to Figure 2 , the horizontal axis direction is the thickness direction of the buffer layer 20, the abscissa d represents the thickness distance between the buffer layer 20 and the substrate 10, the ordinate is the carbon concentration of the buffer layer, the starting point is the carbon concentration at the position where the buffer layer 20 is adjacent to the substrate 10, the carbon concentration in the first part 21 increases linearly, the carbon concentration in the first part 21 gradually increases, the carbon concentration in the second part 23 decreases linearly, and the carbon concentration in the second part 23 gradually decreases.

[0063] Figure 3This is another graph showing the change trend of the carbon concentration of the buffer layer provided in the first embodiment of the present invention. Refer to Figure 3 , the horizontal axis direction is the thickness direction of the buffer layer 20, the abscissa d represents the thickness distance between the buffer layer 20 and the substrate 10, and the ordinate is the carbon concentration of the buffer layer. That is, along the direction from the substrate 10 to the channel layer 30, the carbon concentration in the first part 21 increases periodically. The periodic increase can be a step-like increase. The carbon concentration in the first part 21 adjacent to the substrate 10 is less than that in the first part 21 far from the substrate 10. In other embodiments, optionally, along the direction from the substrate 10 to the channel layer 30, the carbon concentration in the second part 23 decreases periodically. The periodic decrease can be a step-like decrease. The carbon concentration in the second part 23 adjacent to the substrate 10 is greater than that in the second part 23 far from the substrate 10.

[0064] Figure 4 This is another graph showing the change trend of the carbon concentration of the buffer layer provided in the first embodiment of the present invention. Refer to Figure 4 , the horizontal axis direction is the thickness direction of the buffer layer 20, the abscissa d represents the thickness distance between the buffer layer 20 and the substrate 10, and the ordinate is the carbon concentration of the buffer layer. The carbon concentration in the first part 21 increases periodically, and the carbon concentration in the first part 21 shows a step-like increase in each period. In each period, the carbon concentration in the first part 21 adjacent to the substrate 10 is less than that in the first part 21 far from the substrate 10; in adjacent periods, the maximum value of the carbon concentration in the first part 21 of the next period is greater than the maximum value of the carbon concentration in the first part 21 of the previous period, and the minimum value of the carbon concentration in the first part 21 of the next period is less than the maximum value of the carbon concentration in the first part 21 of the previous period; that is, the carbon concentration in the first part 21 increases in an oscillating manner. In other embodiments, optionally, along the direction from the substrate 10 to the channel layer 30, the carbon concentration in the second part 23 decreases periodically, and the carbon concentration in the second part 23 shows a step-like decrease in each period. In each period, the carbon concentration in the second part 23 adjacent to the substrate 10 is greater than that in the second part 23 far from the substrate 10; in adjacent periods, the minimum value of the carbon concentration in the second part 23 of the next period is less than the minimum value of the carbon concentration in the second part 23 of the previous period, and the maximum value of the carbon concentration in the second part 23 of the next period is greater than the minimum value of the carbon concentration in the second part 23 of the previous period; that is, the carbon concentration in the second part 23 decreases in an oscillating manner.

[0065] Figure 5 This is another graph showing the change trend of the carbon concentration of the buffer layer provided in the first embodiment of the present invention. Refer to Figure 5, the horizontal axis direction is the thickness direction of the buffer layer 20, the abscissa d represents the thickness distance between the buffer layer 20 and the substrate 10, the ordinate is the carbon concentration of the buffer layer, and the carbon concentration in the first part 21 increases periodically. The periodic increase can be a sawtooth increase. In each sawtooth cycle, the carbon concentration of the first part 21 gradually increases and then gradually decreases, which is used to increase the breakdown voltage of the device and further prevent leakage. In other embodiments, optionally, the carbon concentration in the second part 23 decreases periodically. The periodic decrease can be a sawtooth decrease. In each sawtooth cycle, the carbon concentration of the second part 23 gradually decreases and then gradually increases, which is used to increase the breakdown voltage of the device and further prevent leakage.

[0066] Embodiment 2

[0067] Based on the above embodiments, the present invention provides a semiconductor structure, and the difference is only that, referring to Figure 6 , Figure 6 is a schematic diagram of a semiconductor structure provided by Embodiment 2 of the present invention. The buffer layer 20 further includes a first insertion layer 22, and the first insertion layer 22 is disposed between the first part 21 and the second part 23.

[0068] Among them, the first insertion layer 22 can be used to prevent device leakage. The material of the first insertion layer 22 is a group III nitride material, and exemplary ones can be any one of AlGaN, AlN / GaN, and AlGaN / GaN.

[0069] Optionally, referring to Figure 6 , the bandgap of the first insertion layer 22 is greater than the bandgaps of the first part 21 and the second part 23.

[0070] Among them, the bandgap of the first insertion layer 22 is greater than the bandgaps of the first part 21 and the second part 23. Due to the difference in the bandgaps of the first insertion layer 22 and the first part 21 and the second part 23, the energy band will undergo a sudden change, and the resulting polarization effect forms a quasi-triangular potential well at the interface. A large number of electrons are confined in this triangular well, and these electrons are quantized in the direction perpendicular to the heterojunction interface. The movement of electrons can be suppressed in the direction perpendicular to the heterojunction interface to further prevent downward leakage of the buffer layer 20, thereby increasing the resistivity and ensuring the two-dimensional electron gas concentration in the channel layer 30.

[0071] Optionally, referring to Figure 6 , the first insertion layer 22 is a group III nitride material, and the first insertion layer 22 is a single-layer structure insertion layer or a superlattice insertion layer.

[0072] Among them, the single-layer structure insertion layer can be an AlGaN insertion layer, and the superlattice insertion layer can be any one of an AlN / GaN superlattice insertion layer and an AlGaN / GaN superlattice insertion layer.

[0073] Optionally, referring to Figure 6 , the first insertion layer 22 includes an Al component, and along the direction from the substrate 10 to the channel layer 30, the Al component in the first insertion layer 22 gradually increases, gradually decreases, or first increases and then decreases.

[0074] Among them, when the Al component in the first insertion layer 22 gradually increases, gradually decreases, or first increases and then decreases, the energy band of the first insertion layer 22 will change, which can further inhibit the movement of electrons. Electrons move along the bottom of the conduction band. Compared with a flat energy band, a changing energy band is more likely to block electrons and further prevent leakage.

[0075] Embodiment III

[0076] The semiconductor structure provided in Embodiment III of the present invention is substantially the same as that in Embodiment I and Embodiment II, and the difference is only that, referring to Figure 7 , Figure 7 is a schematic diagram of another semiconductor structure provided in Embodiment III of the present invention. The buffer layer 20 further includes at least one second insertion layer 24, and the second insertion layer 24 includes an Al component; the first part 21 includes a plurality of first buffer sub-layers 211, and at least one second insertion layer 24 is disposed between two adjacent first buffer sub-layers 211 among the plurality of first buffer sub-layers 211; and / or, the second part 23 includes a plurality of second buffer sub-layers 231, and at least one second insertion layer 24 is disposed between two adjacent second buffer sub-layers 231 among the plurality of second buffer sub-layers 231.

[0077] Among them, the second insertion layer 24 has the same beneficial effect as the first insertion layer 22, and the second insertion layer 24 can also be used to further prevent device leakage. The material of the second insertion layer 24 is a group III nitride material, and exemplary ones can be any one of AlGaN, AlN / GaN, and AlGaN / GaN. At least one second insertion layer 24 is disposed between two adjacent first buffer sub-layers 211 among the plurality of first buffer sub-layers 211. One second insertion layer 24 can be disposed between two adjacent first buffer sub-layers 211, or multiple second insertion layers 24 can be disposed between two adjacent first buffer sub-layers 211. It can be that second insertion layers 24 are disposed between any two adjacent first buffer sub-layers 211, or only between some adjacent first buffer sub-layers 211. The second insertion layer 24 includes an Al component, and along the direction from the substrate 10 to the channel layer 30, the Al component in the first insertion layer 22 gradually increases, gradually decreases, or first increases and then decreases.

[0078] Optionally, referring to Figure 7, the carbon concentration in several first buffer sub-layers 211 increases in a stepped manner, and the carbon concentrations in the first buffer sub-layers 211 on the adjacent two sides of the second insertion layer 24 are different; and / or, the carbon concentration in several second buffer sub-layers 231 decreases in a stepped manner, and the carbon concentrations in the second buffer sub-layers 231 on the adjacent two sides of the second insertion layer 24 are different.

[0079] Among them, the stepped increase in carbon concentration can be further referred to Figure 3 and Figure 4 , the carbon concentration in each first buffer sub-layer 211 increases in a stepped manner, or after combining multiple adjacent first buffer sub-layers 211 in each first buffer sub-layer 211 into a periodic structure, the carbon concentration in the first part 21 increases periodically; and / or, the carbon concentration in each second buffer sub-layer 231 decreases in a stepped manner, or after combining multiple adjacent second buffer sub-layers 231 in each second buffer sub-layer 231 into a periodic structure, the carbon concentration in the second part 23 decreases periodically.

[0080] Optionally, referring to Figure 7 , the carbon concentration in several first buffer sub-layers 211 increases in a sawtooth manner, and the change trends of the carbon concentrations in the first buffer sub-layers 211 on the adjacent two sides of the second insertion layer 24 are different; and / or, the carbon concentration in several second buffer sub-layers 231 decreases in a sawtooth manner, and the change trends of the carbon concentrations in the second buffer sub-layers 231 on the adjacent two sides of the second insertion layer 24 are different.

[0081] Among them, the sawtooth increase in carbon concentration can be further referred to Figure 5 , the change trends of the carbon concentrations in the first buffer sub-layers 211 on the adjacent two sides of each second insertion layer 24 are different, the carbon concentration in the first buffer sub-layer 211 adjacent to the substrate 10 gradually increases, and the carbon concentration in the first buffer sub-layer 211 far from the substrate 10 gradually decreases; or, the carbon concentration in the first buffer sub-layer 211 adjacent to the substrate 10 gradually decreases, and the carbon concentration in the first buffer sub-layer 211 far from the substrate 10 gradually increases; and / or, the change trends of the carbon concentrations in the second buffer sub-layers 231 on the adjacent two sides of each second insertion layer 24 are different, the carbon concentration in the second buffer sub-layer 231 adjacent to the substrate 10 gradually decreases, and the carbon concentration in the second buffer sub-layer 231 far from the substrate 10 gradually increases; or, the carbon concentration in the second buffer sub-layer 231 adjacent to the substrate 10 gradually increases, and the carbon concentration in the second buffer sub-layer 231 far from the substrate 10 gradually decreases.

[0082] Example 4

[0083] The semiconductor structure provided in the fourth embodiment of the present invention is substantially the same as the content of the first to third embodiments, and the difference is only that Figure 8 is a schematic diagram of another semiconductor structure provided in the fourth embodiment of the present invention. Refer toFigure 8 The semiconductor structure further includes: a component inhibition layer 50, which is located between the buffer layer 20 and the channel layer 30.

[0084] Among them, the bandgap width of the component inhibition layer 50 is greater than that of the buffer layer 20. The material of the component inhibition layer 50 can be AlN material, which can inhibit the diffusion of carbon impurities into the channel layer 30 and further avoid carbon impurity contamination in the channel.

[0085] Embodiment Five

[0086] The content of Embodiment Five is substantially the same as that of any one of Embodiments One to Four, and the difference is only that, as Figure 9 shown, Figure 9 is a schematic diagram of the semiconductor structure provided in Embodiment Five. Among them, the buffer layer 20 includes a plurality of stacked structures sequentially formed by a first part 21, a first insertion layer 22, and a second part 23, and a plurality of such stacked structures are sequentially formed on the substrate 10.

[0087] Embodiment Six

[0088] On the basis of the above embodiments, a method for manufacturing a semiconductor structure according to an embodiment of the present invention is provided. Referring to Figure 1 , the manufacturing method includes: providing a substrate 10, and sequentially manufacturing a buffer layer 20, a channel layer 30, and a barrier layer 40 on one side of the substrate 10;

[0089] Among them, manufacturing the buffer layer 20 includes doping the buffer layer 20 with carbon elements. Manufacturing the buffer layer 20 includes manufacturing a first part 21 and a second part 23 that are sequentially stacked on the substrate 10. The first part 21 is located on the side of the buffer layer 20 close to the substrate 10. Along the direction from the substrate 10 to the channel layer 30, the carbon concentration in the first part 21 gradually increases in a preset trend, and the carbon concentration in the second part 23 gradually decreases.

[0090] Optionally, referring to Figure 1 , the carbon concentration in the first part 21 gradually increasing in a preset trend includes the carbon concentration in the first part 21 increasing linearly or periodically.

[0091] Optionally, Figure 10 is a flowchart of a method for manufacturing a buffer layer provided in Embodiment Six of the present invention. Referring to Figure 6 and Figure 10 , manufacturing the buffer layer 20 on one side of the substrate 10 includes:

[0092] S110: Manufacturing the first part 21 on one side of the substrate 10;

[0093] S120: Manufacturing the first insertion layer 22 on the side of the first part 21 away from the substrate 10;

[0094] S130. Prepare a second part 23 on a side of the first insertion layer 22 away from the first part 21.

[0095] Optionally, refer to Figure 6 , the first insertion layer 22 includes an Al component, and along the direction from the substrate 10 to the channel layer 30, the Al component in the first insertion layer 22 gradually increases, gradually decreases, or first increases and then decreases.

[0096] Optionally, refer to Figure 7 , preparing the first part 21 includes preparing a plurality of first buffer sub-layers 211, and / or preparing the second part 21 includes preparing a plurality of second buffer sub-layers 231. Preparing a buffer layer 20 on one side of the substrate 10 further includes:

[0097] Preparing a second insertion layer 24 between two adjacent first buffer sub-layers 211 among the plurality of first buffer sub-layers 211, and / or preparing a second insertion layer 24 between two adjacent second buffer sub-layers 231 among the plurality of second buffer sub-layers 231. The second insertion layer 24 includes an Al component, and along the direction from the substrate 10 to the channel layer 30, the Al component in the second insertion layer 24 gradually increases, gradually decreases, or first increases and then decreases.

[0098] Optionally, refer to Figure 7 , the carbon concentration in the plurality of first buffer sub-layers 211 increases stepwise, and the carbon concentrations in the first buffer sub-layers 211 on two adjacent sides of the second insertion layer 24 are different; and / or the carbon concentration in the plurality of second buffer sub-layers 231 decreases stepwise, and the carbon concentrations in the second buffer sub-layers 231 on two adjacent sides of the second insertion layer 24 are different.

[0099] Optionally, refer to Figure 7 , the carbon concentration in the plurality of first buffer sub-layers 211 increases serratedly, and the changing trends of the carbon concentrations in the first buffer sub-layers 211 on two adjacent sides of the second insertion layer 24 are different; and / or the carbon concentration in the plurality of second buffer sub-layers 231 decreases serratedly, and the changing trends of the carbon concentrations in the second buffer sub-layers 231 on two adjacent sides of the second insertion layer 24 are different.

[0100] Optionally, refer to Figure 9 , preparing the buffer layer 20 on one side of the substrate 10 includes preparing a plurality of stacked structures formed by combining the first part 21, the first insertion layer 22, and the second part 23 in sequence, and a plurality of such stacked structures are formed on the substrate 10 in sequence.

[0101] Optionally, refer to Figure 8 , after preparing the buffer layer 20 on one side of the substrate 10, it further includes:

[0102] Preparing a component inhibiting layer 50 on a side of the buffer layer 20 away from the substrate 10.

[0103] The method for preparing the semiconductor structure provided by the embodiments of the present invention has the same beneficial effects as the semiconductor structure described in any embodiment of the present invention.

[0104] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and no limitations are imposed herein.

[0105] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A semiconductor structure, characterized in that, it includes: a substrate (10), a buffer layer (20), a channel layer (30), and a barrier layer (40) that are sequentially stacked; the buffer layer (20) includes carbon element doping, the buffer layer (20) includes a first part (21) and a second part (23) that are stacked and distributed, the first part (21) is located on the side of the buffer layer (20) close to the substrate (10), along the direction from the substrate (10) to the channel layer (30), the carbon concentration in the first part (21) gradually increases in a preset trend, and the carbon concentration in the second part (23) gradually decreases; wherein, the buffer layer (20) further includes a first insertion layer (22), the first insertion layer (22) is disposed between the first part (21) and the second part (23), and the first insertion layer (22) includes an Al component.

2. The semiconductor structure according to claim 1, characterized in that, the bandgap width of the first insertion layer (22) is greater than the bandgap widths of the first part (21) and the second part (23).

3. The semiconductor structure according to claim 1, characterized in that: the first insertion layer (22) is a group III nitride material, and the first insertion layer (22) is a single-layer structure insertion layer or a superlattice insertion layer.

4. The semiconductor structure according to claim 1, characterized in that: the first insertion layer (22) includes an Al component, and along the direction from the substrate (10) to the channel layer (30), the Al component in the first insertion layer (22) gradually increases, gradually decreases, or first increases and then decreases.

5. The semiconductor structure according to claim 1, characterized in that: the fact that the carbon concentration in the first part (21) gradually increases in a preset trend includes that the carbon concentration in the first part (21) increases linearly or periodically; and / or, the fact that the carbon concentration in the second part (23) gradually decreases includes that the carbon concentration in the second part (23) decreases linearly or periodically.

6. The semiconductor structure according to claim 1, characterized in that: the buffer layer (20) further includes at least one second insertion layer (24), and the second insertion layer (24) includes an Al component; wherein, the first part (21) includes a plurality of first buffer sub-layers (211), and the at least one second insertion layer (24) is disposed between two adjacent first buffer sub-layers (211) among the plurality of first buffer sub-layers (211); and / or, the second part (23) includes a plurality of second buffer sub-layers (231), and the at least one second insertion layer (24) is disposed between two adjacent second buffer sub-layers (231) among the plurality of second buffer sub-layers (231).

7. The semiconductor structure according to claim 6, characterized in that: the carbon concentration in the plurality of first buffer sub-layers (211) increases in a stepped manner, and the carbon concentrations in the first buffer sub-layers (211) on both sides adjacent to the second insertion layer (24) are different; And / or, the carbon concentration in the plurality of second buffer sub-layers (231) decreases stepwise, and the carbon concentrations in the first buffer sub-layers (211) on the adjacent two sides of the second insertion layer (24) are different.

8. The semiconductor structure according to claim 6, wherein: the carbon concentration in the plurality of first buffer sub-layers (211) increases in a sawtooth shape, and the change trends of the carbon concentrations in the first buffer sub-layers (211) on the adjacent two sides of the second insertion layer (24) are different; and / or, the carbon concentration in the plurality of second buffer sub-layers (231) decreases in a sawtooth shape, and the change trends of the carbon concentrations in the first buffer sub-layers (211) on the adjacent two sides of the second insertion layer (24) are different.

9. The semiconductor structure according to claim 1, wherein, further comprising: a component inhibiting layer (50), and the component inhibiting layer (50) is located between the buffer layer (20) and the channel layer (30).

10. The semiconductor structure according to any one of claims 1-9, wherein, the buffer layer (20) includes a plurality of stacked structures formed by sequentially combining the first part (21), the first insertion layer (22), and the second part (23); and the plurality of stacked structures are sequentially formed on the substrate (10).

11. A method for manufacturing a semiconductor structure, wherein, comprising: providing a substrate (10), and sequentially fabricating a buffer layer (20), a channel layer (30), and a barrier layer (40) on one side of the substrate (10); wherein, fabricating the buffer layer (20) includes doping the buffer layer (20) with carbon elements, fabricating the buffer layer (20) includes fabricating a first part (21), a first insertion layer (22), and a second part (23) distributed in a stacked manner, the first part (21) is located on the side of the buffer layer (20) close to the substrate (10), along the direction from the substrate (10) to the channel layer (30), the carbon concentration in the first part (21) gradually increases in a preset trend, the carbon concentration in the second part (23) gradually decreases, and the first insertion layer (22) includes an Al component.

12. The method for manufacturing a semiconductor structure according to claim 11, wherein, the carbon concentration in the first part (21) gradually increases in a preset trend includes that the carbon concentration in the first part (21) increases linearly or periodically; and / or, the carbon concentration in the second part (23) gradually decreases includes that the carbon concentration in the second part (23) decreases linearly or periodically.

13. The method for manufacturing a semiconductor structure according to claim 11, wherein, the first insertion layer (22) includes an Al component, and along the direction from the substrate (10) to the channel layer (30), the Al component in the first insertion layer (22) gradually increases, gradually decreases, or increases first and then decreases.

14. The method for manufacturing a semiconductor structure according to claim 11, wherein, The preparation of the buffer layer (20) further includes preparing at least one second insertion layer (24), and the second insertion layer (24) includes an Al component; wherein, The preparation of the first portion (21) includes preparing a plurality of first buffer sub-layers (211), and preparing a second insertion layer (24) between two adjacent first buffer sub-layers (211) among the plurality of first buffer sub-layers (211); And / or, the preparation of the second portion (23) includes preparing a plurality of second buffer sub-layers (231), and preparing a second insertion layer (24) between two adjacent second buffer sub-layers (231) among the plurality of second buffer sub-layers (231).

15. The method for preparing a semiconductor structure according to claim 14, wherein, The carbon concentration in the plurality of first buffer sub-layers (211) increases stepwise, and the carbon concentrations in the first buffer sub-layers (211) on the two adjacent sides of the second insertion layer (24) are different; And / or, the carbon concentration in the plurality of second buffer sub-layers (231) decreases stepwise, and the carbon concentrations in the first buffer sub-layers (211) on the two adjacent sides of the second insertion layer (24) are different.

16. The method for preparing a semiconductor structure according to claim 14, wherein, The carbon concentration in the plurality of first buffer sub-layers (211) increases serratedly, and the change trends of the carbon concentrations in the first buffer sub-layers (211) on the two adjacent sides of the second insertion layer (24) are different; And / or, the carbon concentration in the plurality of second buffer sub-layers (231) decreases serratedly, and the change trends of the carbon concentrations in the first buffer sub-layers (211) on the two adjacent sides of the second insertion layer (24) are different.

17. The method for preparing a semiconductor structure according to claim 11, wherein, After preparing the buffer layer (20) on one side of the substrate (10), it further includes: Preparing a component inhibition layer (50) on the side of the buffer layer (20) away from the substrate (10).

18. The method for preparing a semiconductor structure according to any one of claims 11-17, wherein, Preparing the buffer layer (20) on one side of the substrate (10) includes preparing a plurality of stacked structures formed by combining the first portion (21), the first insertion layer (22), and the second portion (23) in sequence; the plurality of stacked structures are formed on the substrate (10) in sequence.

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