A semiconductor structure and a method of forming the same

Abstract

The application discloses a semiconductor structure and a forming method thereof. The forming method of the semiconductor comprises a reactor and a substrate. The reactor comprises a reaction area and first and second gas distribution cavities which are communicated with the reaction area. A first reaction gas is introduced into the reaction area through the first gas distribution cavity, and a second reaction gas is introduced into the reaction area through the second gas distribution cavity. The first reaction gas and the second reaction gas are used for P-type layer growth on the substrate. The first reaction gas at least comprises a group V precursor and a first carrier gas, and the second reaction gas at least comprises a P-type doping precursor, a group III precursor and a second carrier gas. The application adjusts the relative flow rate or the relative density of the second carrier gas relative to the first reaction gas, so that the transmission speed of the second reaction gas is faster, the transmission direction is not easy to change, the doping concentration of P-type doping ions in the P-type layer is improved, the doping is more uniform, and the performance of the semiconductor device is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a semiconductor structure and a forming method thereof. BACKGROUND

[0002] III-V compound semiconductors are widely used in the manufacture of optoelectronic devices, power electronics and radio frequency devices due to their semiconductor properties such as wide band gap, wide direct band gap (high photoelectric conversion efficiency), high electron mobility, high temperature resistance, etc. In order to realize the functions of these devices, one important process is P-type doped epitaxial growth. In the P-type doped epitaxial growth process, the P-type doped precursor and the III group precursor are mixed and then enter the reactor to react with the V group precursor to obtain the P-type doped III-V compound semiconductor.

[0003] At present, the commonly used P-type doped precursor is dimethyl magnesium. However, dimethyl magnesium and V group are prone to pre-reaction before reaching the substrate, thereby affecting the doping efficiency and doping uniformity, and ultimately affecting the performance of the device. SUMMARY

[0004] The purpose of the present application is to overcome the defects of low doping efficiency and uneven doping of the P-type doped precursor in the III-V compound semiconductor, to improve the semiconductor structure forming method, to realize the effective transportation of the P-type doped precursor and the doping uniformity, and to improve the performance of the device.

[0005] In order to achieve the above object, the application provides a method for forming a semiconductor structure, comprising: providing a reactor, wherein the reactor comprises a reaction area and a gas shower head located on the top of the reaction area, the gas shower head comprises a first gas distribution cavity and a second gas distribution cavity stacked one above another, and the first gas distribution cavity and the second gas distribution cavity are respectively connected with the reaction area; providing a substrate and placing the substrate in the reaction area; introducing a first reaction gas into the reaction area through the first gas distribution cavity and introducing a second reaction gas into the reaction area through the second gas distribution cavity, and the first reaction gas and the second reaction gas are used for P-type layer growth on the substrate; wherein the first reaction gas at least comprises a group V precursor and a first carrier gas, the first reaction gas output by the first gas distribution cavity has a first density and a first flow rate, the second reaction gas at least comprises a P-type doping precursor, a group III precursor and a second carrier gas, the P-type doping precursor is used for providing P-type doping ions, the second carrier gas output by the second gas distribution cavity has a second density and a second flow rate, the second density is greater than the first density, the second flow rate is greater than the first flow rate, the ratio of the second density to the first density is the relative density of the second carrier gas, and the ratio of the second flow rate to the first flow rate is the relative flow rate of the second carrier gas; and the doping concentration of the P-type doping ions in the P-type layer is increased by adjusting the relative flow rate or the relative density of the second carrier gas.

[0006] Optionally, the relative flow rate or the relative density of the second carrier gas is adjusted so that the doping concentration of the doping precursor in the P-type layer is increased by more than 10 times.

[0007] Optionally, when the relative density is 170%, the relationship between the resistance of the P-type layer and the relative flow rate of the second carrier gas is y=3.652x 2 -28.37x+56.27, and the relationship between the hole in the P-type layer and the relative flow rate of the second carrier gas is y=(8E+16)x+(6E+14).

[0008] Optionally, the relative flow rate of the second carrier gas is 1.5-5 times.

[0009] Optionally, the relative flow rate of the second carrier gas is 3-4.3 times.

[0010] Optionally, when the relative flow rate is 354%, the relationship between the resistance of the P-type layer and the relative density of the second carrier gas is y=4.092x 2 -16.38x+17.17, and the relationship between the hole in the P-type layer and the relative density of the second carrier gas is y=(2E+17)x-(5E+16).

[0011] Optionally, the relative density of the second carrier gas is 1.0-5.0 times.

[0012] Optionally, the relative density of the second carrier gas is 1.5-2.3 times.

[0013] Optionally, the first carrier gas comprises hydrogen.

[0014] Optionally, the first carrier gas further comprises nitrogen.

[0015] Optionally, the second carrier gas comprises nitrogen.

[0016] Optionally, the second carrier gas further comprises hydrogen.

[0017] Optionally, the second gas distribution cavity is isolated into an inner cavity and an outer cavity, so as to independently adjust the relative flow rate or relative density of the second carrier gas passing through the inner cavity and the outer cavity.

[0018] Optionally, the group III precursor comprises at least any one or a combination of group of gallium source precursor, boron source precursor, aluminum source precursor, indium source precursor.

[0019] Optionally, the group V precursor comprises at least a nitrogen source precursor; the nitrogen source precursor is hydrogen nitride.

[0020] Optionally, the P-type doping precursor is dimethyl magnesium.

[0021] The present application further provides a semiconductor structure comprising at least:

[0022] a substrate;

[0023] a P-type layer formed on the substrate, wherein the P-type layer is prepared by the forming method of the semiconductor structure according to any one of the above.

[0024] Optionally, the P-type layer is composed of In x Ga y Al 1-x-y N, wherein 0≤x≤1, 0≤y≤1, 0≤x+y≤1.

[0025] Optionally, the P-type layer is any one of GaN, AlGaN or InAlGaN.

[0026] Compared with the prior art, the technical scheme of the present application has at least the following beneficial effects:

[0027] (1) The present application adjusts the relative flow rate or relative density of the second carrier gas, reduces the pre-reaction of the P-type doping precursor and the group V precursor, prevents the generation of intermediate by-products, and thus the doping concentration of the doping ions in the P-type layer is increased by 10 times, the effective transportation and uniform distribution of the doping ions in the P-type layer are realized, and the performance of the device is improved.

[0028] (2) Further, the gas shower head of the present application comprises a first gas distribution cavity and a second gas distribution cavity stacked one above the other, the second gas distribution cavity is located above the first gas distribution cavity, so that the V-group precursor in the first gas distribution cavity below can receive more heat radiation from the heating assembly inside the cavity, which is beneficial to the decomposition of the V-group precursor and improves the utilization efficiency; wherein the second gas distribution cavity is divided into an inner cavity and an outer cavity, the present application also differentially adjusts the relative flow rate or relative density of the second carrier gas entering the inner cavity and the outer cavity, so that the inner cavity and the outer cavity have different flow rates and densities, which can compensate for the defects of uneven doping caused by the pre-reaction of P-type doped precursor with V-group precursor, so as to realize the radial uniformity adjustment of doped ions. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A flow chart of a semiconductor structure forming method of the present application.

[0030] Figure 2 A schematic diagram of a semiconductor structure forming device of the present application.

[0031] Figure 3 In the method for forming a semiconductor of the present application, when the relative density of the second carrier gas is kept unchanged, the relative flow rate of the second carrier gas and the relationship between the doping efficiency of magnesium in the P-type layer are shown in the schematic diagram.

[0032] Figure 4 In the method for forming a semiconductor of the present application, when the relative flow rate of the second carrier gas is kept unchanged, the relative density of the second carrier gas and the relationship between the doping efficiency of magnesium in the P-type layer are shown in the schematic diagram.

[0033] Wherein, 1-first gas distribution cavity, 2-second gas distribution cavity, 3-reaction area, 4-substrate, 5-isolation wall, 6-gas shower head. DETAILED DESCRIPTION

[0034] The technical solutions of the present application are further described below in combination with the drawings and examples.

[0035] The terms "on", "above" and "over" should be interpreted in the broadest context to mean not only "directly on" but also to include the meaning of being on with other intervening features or layers therebetween, and not only "above" or "over" but also to include the meaning of being "above" or "over" without other intervening features or layers therebetween (i.e., directly on).

[0036] The terms "forming" or "depositing" are used hereinafter to describe the act of applying a layer of material to a substrate. These terms are intended to describe any workable layer forming technique, including but not limited to thermal growth, sputtering, evaporation, chemical vapor deposition, epitaxial growth, electroplating, etc.

[0037] III-V semiconductor materials include compounds containing one element from the "III" column of the periodic table and another element from the "V" column of the periodic table. For example, the III column elements can include boron, aluminum, gallium, indium, etc., and the V column elements can include nitrogen, phosphorus, arsenic, antimony, etc. III-V semiconductor materials, such as gallium nitride (GaN), indium nitride (InN), aluminum nitride (AIN), etc., are typically epitaxially grown on a base substrate using a vapor phase growth method, such as an organometallic vapor phase growth method, a molecular beam vapor phase growth method, a hydride vapor phase growth method, etc. Using the organometallic vapor phase growth method as an example, a III-V compound semiconductor MOCVD (metal organic chemical vapor deposition) reactor has a III column gas distribution chamber and a V column gas distribution chamber, a P-type dopant precursor is typically mixed with a III column precursor and then enters the III column gas distribution chamber through a III column precursor pipe, a V column precursor enters the V column gas distribution chamber through a V column precursor pipe, and the P-type dopant precursor, the III column precursor, and the V column precursor enter a reaction region to epitaxially grow a P-type layer on the base substrate.

[0038] Since the P-type dopant precursor has strong activity, once the P-type dopant precursor, the III column precursor, and the V column precursor are sprayed into the reaction region from the gas showerhead, before reaching the substrate, the P-type dopant precursor is prone to pre-reaction with the V column precursor to generate intermediate byproducts. The pre-reaction will consume the P-type dopant precursor, thereby reducing the amount of P-type dopant precursor reaching the substrate, and further reducing the doping efficiency of the P-type dopant precursor on the substrate.

[0039] To solve the technical problem, the present application at least adopts one of the following technical solutions:

[0040] 1) By adjusting the relative flow rate of the second carrier gas into the second gas distribution chamber, the flow rate of the second reaction gas is greater than that of the first reaction gas, the transmission speed of the second reaction gas in the second gas distribution chamber is faster, the diffusion of the doping ions in the reaction region is reduced, and the collision and contact of the doping ions with the V column precursor are avoided, thereby reducing the pre-reaction.

[0041] 2) by adjusting the relative density size of the second carrier gas into the second gas distribution cavity, so that the density of the second reaction gas is greater than the density of the first reaction gas, when the second reaction gas enters the reaction area, it is not easy to collide with other molecules or collide with other molecules and is not easy to change direction, thereby the transmission direction of the second reaction gas in the second gas distribution cavity is not easy to change, so that more P-type doped ions can reach the surface of the substrate.

[0042] The present application reduces the pre-reaction of the P-type doped precursor and the group V precursor by adjusting the relative flow rate or the relative density size of the second carrier gas as described above, reduces the generation of intermediate by-products, thereby improving the doping efficiency of the P-type doped precursor, and the P-type layer of the semiconductor structure formed is more uniform.

[0043] In order to make the above-mentioned purposes, characteristics and beneficial effects of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0044] Figure 1 is a flow chart of a semiconductor structure forming method of the present application.

[0045] As shown in Figure 1 , the present application provides a semiconductor structure forming method, which comprises:

[0046] Step S1: providing a reactor, the reactor comprising a reaction area and a gas shower head located at the top of the reaction area, the gas shower head comprising a first gas distribution cavity and a second gas distribution cavity stacked one above the other, the first gas distribution cavity and the second gas distribution cavity being respectively communicated with the reaction area.

[0047] The purpose of the first gas distribution cavity and the second gas distribution cavity being respectively communicated with the reaction area is to respectively pass the first reaction gas and the second reaction gas into the reaction area through the first gas distribution cavity and the second gas distribution cavity, so as to avoid the pre-reaction of the first reaction gas and the second reaction gas in the gas shower head, thereby generating intermediate by-products.

[0048] In some embodiments, in order to further realize the effective transport of the P-type doped precursor, the transmission distance between the gas shower head at the top of the reaction area and the upper surface of the substrate is 30mm-90mm, so as to prevent the transmission distance from being too far, causing the first reaction gas and the second reaction gas to pre-react before reaching the substrate, thereby increasing the generation of intermediate by-products and affecting the doping of the P-type doped precursor.

[0049] Step S2: providing a substrate and placing it in the reaction area.

[0050] The substrate can be selected from any one of a silicon substrate, a silicon carbide substrate and a gallium nitride substrate.

[0051] Step S3: introducing a first reaction gas into the reaction region through the first gas distribution cavity and introducing a second reaction gas into the reaction region through the second gas distribution cavity, the first reaction gas and the second reaction gas reacting on the substrate to form a P-type layer.

[0052] The first reaction gas at least contains a group V precursor and a first carrier gas, the first reaction gas output by the first gas distribution cavity has a first density and a first flow rate, the second reaction gas at least contains a P-type doping precursor, a group III precursor and a second carrier gas, the P-type doping precursor is used to provide P-type doping ions, the second carrier gas output by the second gas distribution cavity has a second density and a second flow rate, the second density is greater than the first density, the second flow rate is greater than the first flow rate, the ratio of the second density to the first density is the relative density of the second carrier gas, the ratio of the second flow rate to the first flow rate is the relative flow rate of the second carrier gas; by adjusting the relative flow rate or the relative density of the second carrier gas, the doping concentration of the P-type doping ions in the P-type layer is improved.

[0053] The purpose of this step is to make the first reaction gas and the second reaction gas react on the substrate to grow a P-type layer. In order to avoid the pre-reaction of the group V precursor with the P-type doping precursor and the group III precursor in the gas distribution cavity, the first reaction gas and the second reaction gas are introduced through the first gas distribution cavity and the second gas distribution cavity respectively.

[0054] In order to improve the doping concentration, in some embodiments, by adjusting the relative flow rate of the second carrier gas in the second reaction gas, the flow rate of the second reaction gas is greater than that of the first reaction gas, the transmission speed of the second reaction gas is faster, and thus the pre-reaction of the P-type doping precursor with the group V precursor before reaching the substrate is reduced. In other embodiments, the relative density of the second carrier gas in the second reaction gas can also be adjusted, so that the density of the second reaction gas is greater than that of the first reaction gas, and thus the transmission direction of the second reaction gas is not easy to change, and the pre-reaction of the P-type doping precursor with the group V precursor before reaching the substrate is reduced. The first reaction gas and the second reaction gas perform P-type layer growth on the substrate, reduce the pre-reaction, and thus more P-type doping precursors reach the surface of the substrate, and thus the doping concentration of the P-type doping ions in the P-type layer is improved.

[0055] When the size of the substrate is large, the gas distribution in the edge portion of the substrate is different from that in the center portion of the substrate when the reaction gas is introduced into the substrate in the reaction region through the gas shower head. In particular, the reaction gas can be extracted by the gas pump, which can cause the gas distribution in the edge portion of the substrate to be different from that in the center portion of the substrate. The different gas distributions in different portions of the substrate surface can cause uneven doping of the dopant precursor on the substrate surface. When the gas flow rate or density is greatly different between the center region and the edge region of the gas distribution chamber, a sudden change in the gas flow rate or density can occur at the gas shower head, which can cause a sudden change in the processing effect of the substrate below, and thus cause the gas for the reaction on the substrate to be uneven, which can seriously affect the uniformity of the doping and the quality and efficiency of the substrate processing. To solve this technical problem, in some embodiments of the present application, the second gas distribution chamber is divided into an inner chamber and an outer chamber, the inner chamber corresponds to the center region of the second gas distribution chamber, and the outer chamber corresponds to the edge region surrounding the periphery of the center region. The inner chamber is arranged opposite to the center portion of the substrate in the reaction region, and the outer chamber is arranged opposite to the edge portion of the substrate in the reaction region.

[0056] To achieve the adjustment of the radial doping uniformity of the doping ions, the gas flow rates and densities through the inner chamber and the outer chamber of the second gas distribution chamber can be differentially adjusted. When the gas flow rates through the inner chamber and the outer chamber are greatly different, the flow rate difference between the two can be reduced by adjusting the flow rates of the second carrier gas introduced into the inner chamber and the outer chamber, respectively. Or, when the gas densities through the inner chamber and the outer chamber are greatly different, the density difference between the two can be reduced by adjusting the flow rates of nitrogen and hydrogen in the second carrier gas introduced into the inner chamber and the outer chamber, respectively. Therefore, by differentially adjusting the gas flow rates and densities, the gas can be prevented from being unevenly sprayed onto the substrate when the gas is sprayed out of the shower head through the inner chamber and the outer chamber.

[0057] The III group precursor is an organic metal salt, and in some embodiments, the III group precursor at least includes any one or a combination of multiple of a gallium source precursor, a boron source precursor, an aluminum source precursor, and an indium source precursor. The gallium source precursor at least includes any one or a combination of multiple of trimethyl gallium, triethyl gallium, diethyl gallium chloride, and isotopic hydride gallium compounds; the boron source precursor at least includes any one or a combination of multiple of trimethyl boron and triethyl boron; the aluminum source precursor at least includes any one or a combination of multiple of trimethyl aluminum and triethyl aluminum; and the indium source precursor at least includes any one or a combination of multiple of trimethyl indium and triethyl indium.

[0058] To facilitate the adjustment of the relative flow rate and the relative density, the present application further comprises a carrier gas. The carrier gas does not react with the reaction gas, and the carrier gas of the present application is used to disperse the reaction gas. In the present application, the carrier gas comprises at least two gases with a large difference in density, for example, the carrier gas can be nitrogen or hydrogen, when a larger relative density is required, the flow rate of nitrogen in the second carrier gas can be adjusted, and when a smaller relative density is required, the flow rate of hydrogen in the second carrier gas can be adjusted. In some embodiments, the first carrier gas is used to introduce the group V precursor into the first gas distribution chamber, and the first carrier gas can be any one of hydrogen, nitrogen, or a mixture of hydrogen and nitrogen. In some embodiments, the second carrier gas is used to introduce the group III precursor and the P-type doping precursor into the second gas distribution chamber, and the second carrier gas can be any one of nitrogen, hydrogen, or a mixture of nitrogen and hydrogen.

[0059] The second reaction gas of the present application comprises at least a P-type doping precursor, a group III precursor, and a second carrier gas. Since the amount of the group III precursor is small, generally not more than 1000 sccm, when growing the P-type layer, the P-type doping precursor and the group III precursor are mainly introduced into the second gas distribution chamber by the second carrier gas. Therefore, by adjusting the relative flow rate or the relative density of the second carrier gas, the present application changes the relative flow rate or the relative density of the second reaction gas, so that the second reaction gas has a faster transmission speed and is less likely to change the transmission direction, thereby making the doping of the ions in the P-type layer more uniform.

[0060] To prevent the high-energy ions of the reaction gas from damaging the film on the substrate surface, in some embodiments, the first reaction gas and the second reaction gas are both saturated vapor, the gas molecules are thermally cracked to form clusters at high temperature, and the saturated vapor is introduced into the first gas distribution chamber and the second gas distribution chamber, respectively, and diffuses to the substrate surface for growth by the first carrier gas and the second carrier gas, respectively.

[0061] In some embodiments, the P-type layer can include a P-type doped aluminum nitride layer, a P-type doped gallium nitride layer, or other suitable P-type doped III-V compound materials. Among them, the P-type doping precursor in the P-type doped III-V compound material can include dimethyl magnesium (Cp2Mg), magnesium, or other suitable P-type doping precursors. In the following embodiments of the present application, the P-type doping precursor is dimethyl magnesium.

[0062] Figure 2 is a schematic diagram of a device for forming a semiconductor structure of the present application.

[0063] As Figure 2As shown, the device for forming a semiconductor structure of the present application comprises at least a reactor. The reactor comprises a reaction area 3 and a gas shower head 6 located at the top of the reaction area 3. The gas shower head 6 comprises a first gas distribution cavity 1 and a second gas distribution cavity 2 stacked one above the other. The second gas distribution cavity 2 is located above the first gas distribution cavity 1. The first gas distribution cavity 1 and the second gas distribution cavity 2 are respectively connected to the reaction area 3. The second gas distribution cavity 2 is divided into an inner cavity and an outer cavity by two partition walls 5. A substrate 4 is placed at the bottom of the reaction area 3. The transmission distance between the gas shower head 6 at the top of the reaction area 3 and the substrate 4 at the bottom of the reaction area 3 is 30mm-90mm.

[0064] The working principle of the device for forming a semiconductor structure of the present application is as follows:

[0065] A substrate 4 to be processed is placed at the bottom of the reaction area 3. Purge gas is introduced to purge the substrate 4. First reaction gas is introduced into the first gas distribution cavity 1. Second reaction gas is introduced into the second gas distribution cavity 2. The relative density of the second carrier gas in the second reaction gas is kept unchanged. The relative flow rate of the second carrier gas is adjusted so that the relative flow rate of the second carrier gas is greater than the relative flow rate of the first reaction gas. Alternatively, the relative flow rate of the second carrier gas in the second reaction gas is kept unchanged. The flow rate of nitrogen or hydrogen in the second carrier gas is adjusted so that the relative density of the second carrier gas is greater than the relative density of the first reaction gas.

[0066] Further, the relative flow rate of the second carrier gas introduced into the inner cavity and the outer cavity is respectively adjusted so that the gas introduced into the inner cavity and the outer cavity has different flow rates. Alternatively, the flow rate of nitrogen or hydrogen in the second carrier gas introduced into the inner cavity and the outer cavity is respectively adjusted so that the gas introduced into the inner cavity and the outer cavity has different densities. The first reaction gas and the second reaction gas are respectively sprayed out by the gas shower head 6 and transmitted to the substrate 4 to grow a P-type layer.

[0067] The present application also provides a semiconductor structure comprising a substrate, a compound semiconductor crystal layer represented by the general formula In x Ga y Al 1-x-y N (wherein 0≤x≤1, 0≤y≤1, 0≤x+y≤1) formed on the substrate, and a III-V compound semiconductor having a laminated structure of the compound semiconductor crystal layer.

[0068] In some embodiments, the III-V compound semiconductor layer (P-type layer) can comprise GaN, AlGaN, InAlGaN, or other suitable III-V compound semiconductor materials.

[0069] Embodiment 1

[0070] The embodiment provides a method for forming a semiconductor structure, comprising the following steps:

[0071] Step S1: providing a reactor for forming a semiconductor structure, wherein the reactor comprises a reaction area and a plurality of gas shower heads arranged on the top of the reaction area, the gas shower heads comprise first and second gas distribution cavities arranged in a stack, and the first and second gas distribution cavities are connected with the reaction area respectively;

[0072] Step S2: providing a silicon substrate, placing the silicon substrate at the bottom of the reaction area, and introducing a purge gas to perform a purge treatment on the silicon substrate at the bottom of the reaction area;

[0073] Step S3: taking hydrogen and nitrogen as first carrier gases, under the action of the first carrier gases, keeping ammonia gas of a V-group precursor continuously introduced into the first gas distribution cavity through a V-group precursor pipeline, the first carrier gases and the ammonia gas form a first reaction gas; introducing dimethyl magnesium through a dimethyl magnesium pipeline and introducing trimethyl gallium through a III-group precursor pipeline, after the dimethyl magnesium and the trimethyl gallium are mixed, taking nitrogen and hydrogen as second carrier gases, under the action of the second carrier gases, keeping the dimethyl magnesium and the trimethyl gallium continuously introduced into the second gas distribution cavity, the second carrier gases, the dimethyl magnesium and the trimethyl gallium form a second reaction gas. The flow rates of the component gases are shown in Table 1, wherein the hydride represents the first carrier gas introduced into the first gas distribution cavity, the inner cavity carrier gas represents the second carrier gas introduced into the inner cavity of the second gas distribution cavity, and the outer cavity carrier gas represents the second carrier gas introduced into the outer cavity of the second gas distribution cavity.

[0074] The P-type layer is grown on the silicon substrate by using a metal organic chemical vapor deposition epitaxial growth method, the flow rates of the nitrogen and hydrogen are set through mass flow meters, so as to adjust the relative flow rate and the relative density. When the relative density of the second carrier gas is fixed as 1.7 times, the flow rate of the first reaction gas introduced into the first gas distribution cavity is kept unchanged, the flow rate of the second carrier gas introduced into the second gas distribution cavity is adjusted, so that the flow rate of the second carrier gas is increased from 3 times to 3.5 times and 4.3 times relative to the flow rate of the first reaction gas. Until the required growth thickness is reached, the gases introduced into the first gas distribution cavity and the second gas distribution cavity are stopped.

[0075] Table 1: Flow rates of component gases and relative flow rate and relative density

[0076]

[0077] (wherein, slm and sccm are units of gas flow rate, 1 slm represents that a gas with a weight of 1 liter volume under standard state flows per 1 minute, and 1000 sccm is equivalent to 1 slm.)

[0078] AsFigure 3 As shown, when the relative density is 1.7 times, as the flow rate of the second carrier gas relative to the flow rate of the first reactant gas increases from 3 times to 3.5 times and then to 4.3 times, the hole concentration of P-type gallium nitride continuously increases, and the resistance continuously decreases, indicating that the magnesium doping efficiency is improved. At this time, the relationship between the resistance of the P-type layer and the relative flow rate of the second carrier gas is y = 3.652x. 2 -28.37x+56.27: (where the x-coordinate represents the relative flow rate of the second carrier gas, and the left y-coordinate represents the resistance of the P-type layer). The relationship between the holes in the P-type layer and the relative flow rate of the second carrier gas is y = (8E+16)x + (6E+14) (where the x-coordinate represents the relative flow rate of the second carrier gas, and the right y-coordinate represents the hole concentration in the P-type layer). Therefore, it can be seen that when the relative density of the second carrier gas remains constant, the magnesium doping concentration and doping efficiency in the P-type layer can be increased by adjusting the relative flow rate of the second carrier gas.

[0079] Example 2

[0080] This embodiment provides a method for forming a semiconductor structure, comprising the following steps:

[0081] The difference between this embodiment and Embodiment 1 lies in step S3, where the flow rates of nitrogen and hydrogen are set using mass flow meters to adjust their relative velocity and density. When the relative velocity of the second carrier gas is fixed at 3.54 times, the density of the first reactant gas introduced into the first gas distribution chamber remains constant. The flow rates of nitrogen and hydrogen in the second carrier gas introduced into the second gas distribution chamber are adjusted so that the density of the second carrier gas relative to the density of the first reactant gas increases from 1.5 times to 2.3 times.

[0082] like Figure 4 As shown, when the relative flow rate is 3.54 times that of the first reactant gas, as the density of the second carrier gas increases from 1.5 times to 2.3 times that of the first reactant gas, the hole concentration of P-type gallium nitride continuously increases and the resistance continuously decreases, indicating that the magnesium doping efficiency is improved. At this time, the relationship between the resistance of the P-type layer and the relative density of the second carrier gas is: y = 4.092x 2 -16.38x+17.17 (where the x-coordinate represents the relative density of the second carrier gas, and the y-coordinate on the left represents the resistance of the P-type layer), the relationship between the holes in the P-type layer and the relative density of the second carrier gas is: y=(2E+17)x-(5E+16) (where the x-coordinate represents the relative density of the second carrier gas, and the y-coordinate on the right represents the hole concentration in the P-type layer). Therefore, it can be seen that when the relative flow rate of the second carrier gas remains constant, the doping concentration and doping efficiency of magnesium in the P-type layer can be increased by adjusting the relative density of the second carrier gas.

[0083] In summary, the method for forming a semiconductor structure of the present application keeps the relative density of the second carrier gas unchanged, adjusts the relative flow rate of the second carrier gas to the first reaction gas, or keeps the relative flow rate of the second carrier gas unchanged, adjusts the relative density of the second carrier gas to the first reaction gas, further separates the gas distribution cavity into different chambers, adjusts the radial doping uniformity by differentially adjusting the relative flow rate or the relative density of the gas, significantly improves the doping concentration of magnesium in the P-type layer, improves the doping efficiency of magnesium, makes the doping more uniform, and improves the performance of the semiconductor device.

[0084] Although the present application has been described in detail by the preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present application. Various modifications and substitutions will be apparent to those skilled in the art after reading the above description. Therefore, the scope of the present application should be defined by the appended claims.

Claims

1. A method of forming a semiconductor structure, comprising: The application relates to a semiconductor structure and a forming method thereof. The application provides a reactor, which comprises a reaction area and a gas spray head arranged on the top of the reaction area, wherein the gas spray head comprises a first gas distribution cavity and a second gas distribution cavity arranged in a stack, and the first gas distribution cavity and the second gas distribution cavity are connected with the reaction area respectively. A substrate is arranged in the reaction area. A first reaction gas is introduced into the reaction area through the first gas distribution cavity, and a second reaction gas is introduced into the reaction area through the second gas distribution cavity, so that a P-type layer is formed on the substrate. The first reaction gas comprises at least a V-group precursor and a first carrier gas, the first reaction gas output by the first gas distribution cavity has a first density and a first flow rate, the second reaction gas comprises at least a P-type doping precursor, a III-group precursor and a second carrier gas, the P-type doping precursor is used for providing P-type doping ions, the second carrier gas output by the second gas distribution cavity has a second density and a second flow rate, the second density is greater than the first density, the second flow rate is greater than the first flow rate, the ratio of the second density to the first density is the relative density of the second carrier gas, and the ratio of the second flow rate to the first flow rate is the relative flow rate of the second carrier gas. The relative flow rate or the relative density of the second carrier gas is adjusted, so that the doping concentration of the P-type doping ions in the P-type layer is increased by more than 10 times.

2. The method of forming a semiconductor structure of claim 1, wherein, The relative flow rate of the second carrier gas is 1.5-5 times.

3. The method of forming a semiconductor structure of claim 1, wherein When the relative density is 170%, the resistance of the P-type layer is related to the relative flow rate of the second carrier gas by the equation: y = 3.652x 2 -28.37x + 56.27, where x represents the relative flow rate of the second carrier gas and y represents the resistance of the P-type layer; and the holes in the P-type layer are related to the relative flow rate of the second carrier gas by the equation: y = (8E+16)x + (6E+14), where x represents the relative flow rate of the second carrier gas and y represents the hole concentration in the P-type layer.

4. The method of forming a semiconductor structure of claim 3, wherein, The relative flow rate of the second carrier gas is 3-4.3 times.

5. The method of forming a semiconductor structure of claim 4, wherein, The relative density of the second carrier gas is 1.0-5.0 times.

6. The method of forming a semiconductor structure of claim 1, wherein, When the relative flow rate is 354%, the resistance of the P-type layer is related to the relative density of the second carrier by the equation: y = 4.092x 2 -16.38x + 17.17, where x represents the relative density of the second carrier and y represents the resistance of the P-type layer; and the holes in the P-type layer are related to the relative density of the second carrier by the equation: y = (2E+17)x - (5E+16), where x represents the relative density of the second carrier and y represents the hole concentration in the P-type layer.

7. The method of forming a semiconductor structure of claim 6, wherein, The relative density of the second carrier gas is 1.5-2.3 times.

8. The method of forming a semiconductor structure of claim 7, wherein, The first carrier gas comprises hydrogen.

9. The method of forming a semiconductor structure of claim 1, wherein, The first carrier gas further comprises nitrogen.

10. The method of forming a semiconductor structure of claim 9, wherein, The second carrier gas comprises nitrogen.

11. The method of forming a semiconductor structure of claim 1, wherein, The second carrier gas further comprises hydrogen.

12. The method of forming a semiconductor structure of claim 11, wherein, The second gas distribution cavity is separated into an inner cavity and an outer cavity, so that the relative flow rate or the relative density of the second carrier gas passing through the inner cavity and the outer cavity can be independently adjusted.

13. The method of forming a semiconductor structure of claim 1, wherein, The III-group precursor comprises at least any one or any combination of a gallium source precursor, a boron source precursor, an aluminum source precursor and an indium source precursor.

14. The method of forming a semiconductor structure of claim 1, wherein, The V-group precursor comprises at least a nitrogen source precursor, and the nitrogen source precursor is hydrogen nitride.

15. The method of forming a semiconductor structure of claim 1, wherein, The P-type doping precursor is dimethyl magnesium.

16. The method of forming a semiconductor structure of claim 1, wherein, The application further provides a semiconductor structure formed by the forming method.

17. A semiconductor structure, characterized by The semiconductor structure comprises at least a substrate and a P-type layer formed on the substrate. The P-type layer is formed by the forming method of the semiconductor structure. The P-type layer is any one of GaN, AlGaN or InAlGaN.

18. The semiconductor structure of claim 17, wherein, ​ In x Ga y Al 1-x-y N indicates, wherein 0≤x≤1, 0≤y≤1, 0≤x+y≤1.

19. The semiconductor structure of claim 18, wherein, ​

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