WO2022037709A1 - 一种基于超临界氮氧化合物改善4H-SiC/SiO2界面的低温处理方法及其应用 - Google Patents

一种基于超临界氮氧化合物改善4H-SiC/SiO2界面的低温处理方法及其应用 Download PDF

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WO2022037709A1
WO2022037709A1 PCT/CN2021/118871 CN2021118871W WO2022037709A1 WO 2022037709 A1 WO2022037709 A1 WO 2022037709A1 CN 2021118871 W CN2021118871 W CN 2021118871W WO 2022037709 A1 WO2022037709 A1 WO 2022037709A1
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刘卫华
王梦华
耿莉
杨明超
郝跃
杨松泉
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Xian Jiaotong University
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D12/00—Bipolar devices controlled by the field effect, e.g. insulated-gate bipolar transistors [IGBT]
    • H10D12/01—Manufacture or treatment
    • H10D12/031—Manufacture or treatment of IGBTs
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D64/00—Electrodes of devices having potential barriers
    • H10D64/01—Manufacture or treatment
    • H10D64/013—Manufacture or treatment of electrodes having a conductor capacitively coupled to a semiconductor by an insulator
    • H10D64/01366—Manufacture or treatment of electrodes having a conductor capacitively coupled to a semiconductor by an insulator the semiconductor being silicon carbide
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
    • H10D62/80—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials
    • H10D62/83—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials being Group IV materials, e.g. B-doped Si or undoped Ge
    • H10D62/832—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials being Group IV materials, e.g. B-doped Si or undoped Ge being Group IV materials comprising two or more elements, e.g. SiGe
    • H10D62/8325—Silicon carbide
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D8/00—Diodes
    • H10D8/01—Manufacture or treatment
    • H10D8/051—Manufacture or treatment of Schottky diodes

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  • the invention belongs to the technical field of the third-generation wide band gap semiconductor material, and in particular relates to a low-temperature treatment method based on supercritical oxynitride to improve 4H-SiC/SiO 2 interface and its application.
  • SiC Silicon carbide
  • SiC devices As a typical third-generation wide-bandgap semiconductor, has many excellent properties. Compared with ordinary Si, SiC devices have the characteristics of high voltage resistance, high frequency resistance, high temperature resistance, and long life, which make them suitable for frontier applications such as rail transit, new energy vehicles, photovoltaic inverters, renewable energy power generation, military industry and national defense. Widely used in the field of science and technology. At present, in the field of high-power devices, SiC MOSFETs with high operating frequency and low on-resistance have broad application prospects, but the widespread commercialization of SiC MOSFETs is still relatively slow, and the reliability of SiC devices is the key to limiting the further expansion of the application field. factor.
  • the channel mobility of SiC MOSFETs is only about 5% of the bulk material mobility, and the low channel mobility is mainly due to the high SiO 2 /SiC interface state density and oxide charge density, especially SiO 2
  • the interface state density of /4H-SiC is nearly two orders of magnitude higher than that of the SiO 2 /Si interface.
  • a higher interface state density will cause problems such as reduced reverse channel mobility, slower switching speed, increased leakage current, and increased threshold voltage.
  • the interface quality has become the main factor limiting the performance of SiC devices. Therefore, the method of reducing the interface state has become the focus of SiC device research.
  • the annealing process after oxidation is mainly used to reduce the 4H-SiC/ SiO2 interface state density and improve the characteristics of the MOS interface.
  • the conventional thermal annealing temperature is in the range of 1000-1500 °C, and the 4H-SiC/ SiO2 interface state density is often reduced in a nitrogen-oxygen or POCl3 gas atmosphere.
  • NO annealing at 1150 °C after high temperature oxidation can significantly reduce the interface state density near the Ec of the 4H-SiC/SiO 2 MOS device, and a passivation study on the bonding of N atoms to C atoms and C clusters was proposed. possible explanations for the effect.
  • NO is a harmful gas with a high hazard factor to health, so for safety reasons, N 2 O is preferable to NO because it has less operational requirements.
  • researches on the reduction of interface states by high temperature N 2 O annealing have emerged one after another.
  • N 2 O is unstable at high temperature and will be decomposed into NO, O 2 and N 2 , mainly relying on NO to reduce the interface state density, and the O 2 released by N 2 O under high temperature environment will oxidize the oxide layer again, and Prevent N from entering the oxide layer and the interface, and re-oxidation will also generate new defects at the interface, so the annealing effect of N 2 O is not as good as that of NO.
  • annealing in POCl 3 atmosphere can also effectively reduce the interface state density.
  • the channel mobility of lateral 4H-SiC MOSFETs is close to 90 cm 2 /(V s), and the mobility is improved.
  • POCl 3 annealing will cause the negative drift of the device threshold and reduce the reliability of the oxide layer.
  • the researchers used ultra-high temperature argon (Ar) annealing (about 1300-1500 °C) to reduce the interface state density. But after high temperature pure Ar annealing, higher leakage currents were observed even at very low electric fields ( ⁇ 0.2MV/cm).
  • high temperature annealing reduces device stability and may lead to additional leakage currents. Therefore, it is necessary to find a low-temperature processing method to obtain high-quality interfaces.
  • the technical problem to be solved by the present invention is to provide a low-temperature treatment method based on supercritical oxynitride to improve the 4H - SiC/SiO 2 interface and its application in view of the deficiencies in the above-mentioned prior art.
  • the high density of interface states and the low mobility of 4H-SiC MOSFETs provide a method to fabricate 4H-SiC MOS devices with high interface quality and carrier mobility without requiring high temperature.
  • the present invention adopts following technical scheme:
  • a low-temperature processing method based on supercritical oxynitride to improve 4H - SiC/SiO interface comprising the following steps:
  • step S4 maintaining the temperature and pressure of the step S3 heating and boosting treatment to fully react, and then reducing the pressure to atmospheric pressure and taking out the sample to complete the low-temperature treatment.
  • step S2 the content of nitrogen and oxygen gas is greater than or equal to 10% of the volume of the reaction kettle of the steady state supercritical equipment, and the initial pressure is 5-25 MPa.
  • the nitrogen-oxygen gas includes N 2 O and NO
  • the remaining gas in the reaction kettle of the steady state supercritical equipment includes O 2 and N 2 .
  • step S3 the temperature of the steady-state supercritical equipment is 50-500° C., and the pressure is 10-100 MPa.
  • step S4 the reaction time in the supercritical state is 1-5 hours.
  • the interface state density of 4H-SiC/SiO 2 after low temperature treatment is 1 ⁇ 10 11 ⁇ 1 ⁇ 10 12 eV -1 cm -2
  • the breakdown electric field is 10 ⁇ 13MV/cm
  • the gate oxygen leakage current density is 1 ⁇ 10 -10 to 1 ⁇ 10 -8 A ⁇ cm -2 .
  • the present invention is also characterized in that the capacitor device processed by the low temperature treatment method based on supercritical oxynitride to improve the 4H-SiC/SiO 2 interface is used in aerospace, detection and sensing and new energy vehicles.
  • the present invention at least has the following beneficial effects:
  • the invention is a low-temperature treatment method based on supercritical oxynitride to improve 4H-SiC/SiO 2 interface, without adding any reactants, only the device needs to be put into the reactor, the operation is simple, and the SiO 2 / SiO 2 / SiO 2 / SiO 2 / SiO 2 / SiO 2 / The improvement of the 4H-SiC interface, the processing temperature is only 50-500 ° C, the operation is simple, and the quality of the oxide layer and the interface is also improved while the process temperature is effectively reduced.
  • the initial pressure of 5-25 MPa is charged into the reaction kettle, and then the equipment is heated up on the basis of this pressure to carry out the corresponding boosting process, so as to ensure that the entire system can reach the supercritical state and also ensure that the reaction is carried out quickly and effectively.
  • nitrogen-oxygen gas including N 2 O and NO
  • other gases including O 2 and N 2 can passivate SiO 2 /4H-SiC interface defects more effectively and improve the interface quality.
  • the treatment in the supercritical state for 1-5 hours ensures that the passivation reaction can be carried out completely and completely under different supercritical treatment conditions.
  • the mobility of the prepared 4H-SiC MOS capacitor devices and 4H-SiC MOSFET devices is improved, and the quality of the oxide layer is improved, laying a foundation for the further preparation of high-performance SiC MOSFETs.
  • the present invention can not only effectively reduce the interface state density but also significantly reduce the process temperature.
  • the advantage lies in that the reaction temperature is low, and the nitroxide gas will not exceed the temperature. It is decomposed in a critical state, and there will be no secondary oxidation, which reduces the generation of additional defects.
  • the supercritical fluid has a large reaction density, and in the supercritical state, it can not only reduce the interface state quickly and efficiently, but also improve the quality of the oxide layer.
  • Fig. 1 is the schematic diagram of supercritical experimental equipment
  • FIG. 2 is a graph showing the results of interface state density treatment before and after supercritical oxynitride treatment.
  • FIG. 3 is a graph showing the results of the breakdown electric field treatment before and after the supercritical oxynitride treatment.
  • a supercritical fluid refers to a fluid in which the substance is in the region of temperature and pressure above the critical point.
  • Supercritical fluid has very unique physical and chemical properties, its density is close to that of liquid, its viscosity is close to that of gas, its diffusion coefficient is large, its viscosity is small, and its dielectric constant is large.
  • the present invention provides a low-temperature treatment method based on supercritical oxynitride to improve 4H-SiC/SiO 2 interface and its application.
  • the traps in the SiO 2 /4H-SiC interface are passivated at a treatment temperature of 50-500° C. Avoid the problems caused by the above-mentioned high temperature process.
  • the supercritical fluid (SCF) state is a special phase of matter with the coexistence of liquid and gaseous phases, the supercritical nitrogen-oxygen environment has the advantages of gas-like high solubility and liquid-like permeability. Therefore, the supercritical oxynitride fluid is allowed to enter the oxide and the interface to passivate the oxide layer traps and interface states at low temperature, thereby improving the interface quality and enhancing the mobility of SiC MOSFETs.
  • a low-temperature treatment method based on supercritical oxynitride to improve the 4H - SiC/SiO interface of the present invention comprises the following steps:
  • the steady state supercritical equipment includes a reaction kettle 1, the side and bottom surfaces of the reaction kettle 1 are respectively provided with a first Omega K-type thermocouple 2 and a second Omega K-type thermocouple 3, and the outside of the reaction kettle 1 is provided with a thermal insulation Layer 6, a heating system is arranged in the thermal insulation layer 6; the first Omega K-type thermocouple 2 and the second Omega K-type thermocouple 3 are respectively connected with the SCR temperature controller 5 through the Eurotherm temperature controller 4, and through the Eurotherm temperature controller 4 Perform temperature display; the SCR temperature controller 5 is connected to the heating system for controlling the heating adiabatic resistor to heat the kettle body of the reactor 1.
  • the flange of the reactor 1 is provided with a high-pressure pipeline to connect the blasting valve 7, the pressure gauge 8 and the high-pressure valve. 9.
  • N 2 O nitrogen-oxygen gas
  • NO gas nitrogen-oxygen gas
  • gases include but are not limited to O 2 , N 2 gas, and the initial pressure is 5 ⁇ 25MPa;
  • a 4H-SiC MOS capacitor device the interface state density is 1 ⁇ 10 11 ⁇ 1 ⁇ 10 12 eV -1 cm -2 , the breakdown electric field is 10 ⁇ 13MV/cm, and the gate oxide leakage current density is 1 ⁇ 10 -10 ⁇ 1 ⁇ 10 ⁇ 8 A ⁇ cm ⁇ 2 . It has broad application prospects in aerospace, detection sensing, new energy vehicles, etc.
  • the temperature of the supercritical equipment is raised to 50°C, and the pressure is raised to 10MPa;
  • the temperature of the supercritical equipment is raised to 100°C, and the pressure is raised to 40MPa;
  • the temperature of the supercritical equipment is raised to 250°C, and the pressure is raised to 60MPa;
  • the temperature of the supercritical equipment is raised to 350°C, and the pressure is raised to 80MPa;
  • the temperature of the supercritical equipment is raised to 500°C, and the pressure is raised to 100MPa;
  • the present invention fully considers the effect of different oxynitride compounds on the interface improvement, and finally obtains an optimal supercritical formula according to different supercritical treatment effects, so as to improve the mobility of the 4H-SiC MOSFET.
  • the n-type 4H-SiC semiconductor material is subjected to high temperature oxidation after standard cleaning, and then put into a reaction kettle and filled with nitrogen-oxygen gas; the temperature is raised so that the nitrogen-oxygen gas is in a supercritical state, and the pressure rises with the temperature; and a fixed processing temperature is reached. After reducing the pressure, the supercritical state was continued until the end of the reaction time; the temperature was lowered, the pressure was reduced to atmospheric pressure, and the processed samples were taken out. The whole process is easy to operate and the temperature is low.
  • the supercritical nitrogen-oxygen gas treatment can quickly and efficiently reduce the SiO 2 /4H-SiC interface state density in a low temperature environment, improve the quality of the oxide layer, and improve the mobility of 4H-SiC MOSFETs.
  • Drawing from the experimental data it can be seen from Figure 2 that the interface state density is reduced by more than one order of magnitude.
  • the breakdown electric field of the device after treatment increased from 9.7MV/cm to 10.8MV/cm.
  • a low-temperature treatment method based on supercritical oxynitride to improve the 4H-SiC/SiO 2 interface of the present invention can quickly and efficiently reduce the SiO 2 /4H-SiC interface state density in a low-temperature environment, improve oxidation layer quality and improve the mobility of 4H-SiC MOSFETs.

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Abstract

本发明公开了一种基于超临界氮氧化合物改善4H-SiC/SiO2界面的低温处理方法及其应用，将待处理的碳化硅样品进行标准清洗；将清洗后的碳化硅样品干氧氧化生长氧化层；将带有氧化层的碳化硅样品放置到超临界设备内支架上，保证样品垂直；控制压强向超临界设备内充入氮氧气体；将超临界设备温度从23℃升到500℃；保持以上超临界状态处理，直到处理时间结束；反应结束后将反应釜温度降至室温，降压至大气压后取出。本发明不仅可以有效快速的降低界面态密度还可以显著降低工艺温度。

Description

一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法及其应用 技术领域
本发明属于第三代宽禁带半导体材料技术领域，具体涉及一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法及其应用。
背景技术
碳化硅(SiC)作为典型的第三代宽禁带半导体，拥有很多优异的特性。与普通的Si相比，SiC器件具有耐高压、耐高频、耐高温、高寿命等特点，使其可以在轨道交通、新能源汽车、光伏逆变器、可再生能源发电、军工国防等前沿科技领域广泛应用。目前在大功率器件领域，工作频率高，导通电阻低的SiC MOSFET具有广阔的应用前景，但是SiC MOSFET广泛的商业化进程仍然比较缓慢，其中SiC器件可靠性问题是限制应用领域进一步扩展的关键因素。一般情况下，SiC MOSFET的沟道迁移率仅为体材料迁移率的5％左右，沟道迁移率低的原因主要在于SiO 2/SiC界面态密度和氧化物电荷密度较高，尤其是SiO 2/4H-SiC的界面态密度要比SiO 2/Si界面高出近两个数量级。较高的界面态密度会引起反向沟道迁移率降低，开关速度减慢，漏电流增大，阈值电压增大等问题，界面质量成为了限制SiC器件性能的主要因素。因此界面态的降低方法成为了SiC器件研究的重点。
为了降低4H-SiC/SiO 2界面态密度，提高SiC MOSFET的迁移率，研究者进行了多种不同的尝试。目前，氧化后的退火工艺主要用于降低4H-SiC/SiO 2界面态密度并改善MOS界面的特性。常规热退火温度在1000-1500℃范围内，常在氮氧或POCl 3气体氛围下降低4H-SiC/SiO 2界面态密度。例如，高温氧化后在1150℃条件下进行NO退火，会使4H-SiC/SiO 2MOS器件Ec附近的界面态密度显著降低，并且提出了关于N原子与C原子和C团簇键合的钝化效果的可能解释。但是NO是有害气体，对健康的危害系数较高，因此出于安全原因，N 2O比NO更 为可取，因为它对操作的要求不高。近年来，研究者对于高温N 2O退火降低界面态的研究层出不穷，已经证明在1100℃的N 2O气氛下高温退火，可以使距离导带0.2eV处的界面态密度显著降低，并且提出降低界面态密度是由于N原子不仅可以钝化Si悬键，形成Si-N键还可以与C团簇形成C-N键从而降低干氧氧化带来的缺陷。然而N 2O在高温下不稳定，会分解为NO，O 2和N 2，主要依靠NO来降低界面态密度，而且在高温环境下N 2O释放的O 2会使氧化层再次氧化，并且阻止N进入氧化层和界面，再次氧化也会在界面产生新的缺陷，因此N 2O的退火效果不如NO的好。
除了在含氮氧气体氛围中高温退火，在POCl 3气氛下退火也能有效降低界面态密度，退火后横向4H-SiC MOSFETs沟道迁移率接近90cm 2/(V·s)，迁移率提高效果明显好于NO处理，但POCl 3退火会造成器件阈值的负漂现象，且氧化层可靠性下降。
为了提高界面质量，研究人员采用超高温氩气(Ar)退火(约1300～1500℃)来降低界面态密度。但是在高温纯Ar退火后，即使在非常低的电场(<0.2MV/cm)下也能观察到较高的泄漏电流。
此外，高温退火会降低器件的稳定性，并可能导致额外的漏电流。因此，寻找一种低温处理方法以获得高质量的界面是十分必要的。
发明内容
本发明所要解决的技术问题在于针对上述现有技术中的不足，提供一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法及其应用，针对目前SiO 2/4H-SiC界面态密度高且4H-SiC MOSFET迁移率低等难题，提供操作简便无需高温，制备具有高界面质量和载流子迁移率的4H-SiC MOS器件的方法。
本发明采用以下技术方案：
一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，包括以下步骤：
S1、将带有氧化层的碳化硅样品放置到稳态超临界设备内，并保证碳化硅样品垂直；
S2、将稳态超临界设备密封，充入氮氧气体，并控制初始压强；
S3、对稳态超临界设备进行升温升压处理；
S4、保持步骤S3升温升压处理的温度和压强充分反应，然后降压至大气压后将样品取出，完成低温处理。
具体的，步骤S2中，氮氧气体的含量大于等于稳态超临界设备反应釜体积的10％，初始压强为5～25MPa。
进一步的，氮氧气体包括N 2O和NO，稳态超临界设备反应釜内的剩余气体包括O 2和N 2。
具体的，步骤S3中，稳态超临界设备的温度为50～500℃，压强为10～100MPa。
具体的，步骤S4中，在超临界状态下的反应时间为1～5h。
具体的，低温处理后4H-SiC/SiO 2的界面态密度为1×10 11～1×10 12eV -1cm -2，击穿电场为10～13MV/cm，栅氧漏电流密度为1×10 -10～1×10 -8A·cm -2。
更进一步的，本发明的特点还在于：基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法处理的电容器件在航空航天、探测传感和新能源汽车方面的应用。
与现有技术相比，本发明至少具有以下有益效果：
本发明一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，无需添加任何反应物，只需将器件放入反应釜内，操作简便，在高压下完成对SiO 2/4H-SiC界面的改善，处理温度只有50-500℃，操作简便，有效降低工艺温度的同时，还改善了氧化层和界面的质量。
进一步的，向反应釜内冲入起始压强5～25MPa，然后使得设备在此压强基础上升温进行相应的升压过程，保证整个体系能够达到超临界状态的同时，也能保证反应快速有效进行。
进一步的，使用氮氧气体包括N 2O和NO，其他气体包括O 2和N 2能更有效的钝化SiO 2/4H-SiC界面缺陷，提升界面质量。
进一步的，在50～500℃，10～100MPa超临界状态下进行处理，氮氧气体不会在超临界状态下分解，也不会二次氧化，降低额外缺陷的产生。
进一步的，在超临界状态下处理1～5h，保证在不同超临界处理条件下钝化反应都能进行的完全和彻底。
进一步的，由于SiO 2/4H-SiC界面态密度的降低，使制备的4H-SiC MOS电容器件和4H-SiC MOSFET器件迁移率提高，氧化层质量提升，为进一步制备高性能SiC MOSFET打下基础。
综上所述，本发明不仅可以有效降低界面态密度还可以显著降低工艺温度，与传统高温(1000℃以上)氮氧化合物退火工艺相比，优势在于反应温度低，氮氧气体不会在超临界状态下分解，也不会二次氧化，降低额外缺陷的产生。且超临界流体反应密度大，在超临界状态下不仅能快速高效的降低界面态，还能提升氧化层质量。
下面通过附图和实施例，对本发明的技术方案做进一步的详细描述。
附图说明
图1为超临界实验设备的原理图；
图2为超临界氮氧化合物处理前后的界面态密度处理结果图。
图3为超临界氮氧化合物处理前后的击穿电场处理结果图。
其中，1.反应釜；2.第一Omega K型热电偶；3.第二Omega K型热电偶；4.欧陆温控仪；5.SCR温度控制器；6.保温层；7.爆破阀；8.压力表；9.高压阀；
具体实施方式
在不同的温度和压力下，物质的状态会发生变化，出现液体、气体、固体等不同的状态。在特定的温度、压力下，会出现液体与气体界面消失的现象，该点被称为临界点。超临界流体指的是物质处于临界点以上温度和压力区域下的流体。超临界流体具有十分独特的物理化学性质，它的密度接近于液体，粘度接近于气体，扩散系数大、粘度小、介电常数大。
本发明提供了一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法及其应用，在50～500℃处理温度下钝化SiO 2/4H-SiC界面中的陷阱，以避免上述高温过程带来的问题。由于超临界流体(SCF)状态是一种特殊的物质相，具有液相和气相的共存特征，所以超临界氮氧环境具有气体般的高溶解能力和液体般的渗透性的优点。因此，允许超临界氮氧流体进入到氧化物和界面中，以在低温下钝化氧化层陷阱和界面态，从而改善界面质量，提升SiC MOSFET的迁移率。
本发明一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，包括以下步骤：
S1、将带有氧化层的碳化硅样品放置到稳态超临界设备内，并保证样品垂直；
请参阅图1，稳态超临界设备包括反应釜1，反应釜1的侧面和底面分别设置有第一Omega K型热电偶2和第二Omega K型热电偶3，反应釜1外部设置有保温层6，保温层6内设置有加热系统；第一Omega K型热电偶2和第二Omega K型热电偶3分别经欧陆温控仪4与SCR温度控制器5连接，通过欧陆温控仪4进行温度显示；SCR温度控制器5连接加热系统用于控制加热绝热电阻器对反应釜1的釜体进行加热，反应釜1的法兰上有高压管道连接爆破阀7、压力表8及高压阀9。
S2、将稳态超临界设备密封，反应釜内充入不低于10％的氮氧气体，如N 2O，NO气体等，其他气体包括但不限于O 2，N 2气体，初始压强为5～25MPa；
S3、将超临界反应釜升温至50～500℃，压强升至10～100MPa；
S4、在50～500℃，10～100MPa超临界状态下，保持以上超临界状态处理1～5h，然后降压至大气压后将样品取出。
一种4H-SiC MOS电容器件，界面态密度为1×10 11～1×10 12eV -1cm -2，击穿电场为10～13MV/cm，栅氧漏电流密度为1×10 -10～1×10 -8A·cm -2。在航空航天、探测传感、新能源汽车等方面具有广泛的应用前景。
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。通常在此处附图中的描述和所示的本发明实施例的组件可以通过各种不同的配置来布置和设计。因此，以下对在附图中提供的本发明的实施例的详细描述并非旨在限制要求保护的本发明的范围，而是仅仅表示本发明的选定实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
实施例1
一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，
S1、将带有氧化层的碳化硅样品放置到超临界设备内支架上，保证样品垂直；
S2、将超临界设备密封，向超临界设备内充入70％N 2O和30％的O 2，使设备充入5MPa的初始压强；
S3、将超临界设备升温至50℃，压强升至10MPa；
S4、在50℃，10MPa超临界处理条件下，保持以上超临界状态处理1h，然后降压至大气压将样品取出；
实施例2
一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，
S1、将带有氧化层的碳化硅样品放置到超临界设备内支架上，保证样品垂直；
S2、将超临界设备密封，向超临界设备内充入70％N 2O和30％的N 2，使设备充入10MPa的初始压强；
S3、将超临界设备升温至100℃，压强升至40MPa；
S4、在100℃，40MPa超临界处理条件下，保持以上超临界状态处理2h，然后降压至大 气压将样品取出；
实施例3
一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，
S1、将带有氧化层的碳化硅样品放置到超临界设备内支架上，保证样品垂直；
S2、将超临界设备密封，向超临界设备内充入70％NO和30％的N 2，使设备充入15MPa的初始压强；
S3、将超临界设备升温至250℃，压强升至60MPa；
S4、在250℃，60MPa超临界处理条件下，保持以上超临界状态处理3h，然后降压至大气压将样品取出；
实施例4
一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，
S1、将带有氧化层的碳化硅样品放置到超临界设备内支架上，保证样品垂直；
S2、将超临界设备密封，向超临界设备内充入100％N 2O，使设备充入20MPa的初始压强；
S3、将超临界设备升温至350℃，压强升至80MPa；
S4、在350℃，80MPa超临界处理条件下，保持以上超临界状态处理4h，然后降压至大气压将样品取出；
实施例5
一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，
S1、将带有氧化层的碳化硅样品放置到超临界设备内支架上，保证样品垂直；
S2、将超临界设备密封，向超临界设备内充入100％NO，使设备充入25MPa的初始压强；
S3、将超临界设备升温至500℃，压强升至100MPa；
S4、在500℃，100MPa超临界处理条件下，保持以上超临界状态处理5h，然后降压至大 气压将样品取出；
本发明充分考虑了不同氮氧化合物对界面的改善影响，根据不同的超临界处理效果最终得出最优的超临界配方，提升4H-SiC MOSFET的迁移率。
本发明将n型4H-SiC半导体材料标准清洗后进行高温氧化，然后放入反应釜中并充入氮氧气体；升温使氮氧气体处于超临界状态，且压强随温度上升；达到固定处理温度和压强后，将超临界状态持续直到反应时间结束；降温，将压力降至大气压后取出处理完的样品。整个过程操作简单，且温度较低。
请参阅图2和图3，采用超临界氮氧气体处理，能够快速、高效的在低温环境下降低SiO 2/4H-SiC界面态密度，改善氧化层质量，提升4H-SiC MOSFET的迁移率。根据实验数据作图，从图2可以看出界面态密度降低了不止1个数量级。从图3可以看出处理后器件的击穿电场从9.7MV/cm提升到10.8MV/cm。
综上所述，本发明一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，能够快速、高效的在低温环境下降低SiO 2/4H-SiC界面态密度，改善氧化层质量，提升4H-SiC MOSFET的迁移率。
以上内容仅为说明本发明的技术思想，不能以此限定本发明的保护范围，凡是按照本发明提出的技术思想，在技术方案基础上所做的任何改动，均落入本发明权利要求书的保护范围之内。

Claims (10)

  1. 一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，其特征在于，包括以下步骤：
    S1、将带有氧化层的碳化硅样品放置到稳态超临界设备内，并保证碳化硅样品垂直；
    S2、将稳态超临界设备密封，充入氮氧气体，并控制初始压强；
    S3、对稳态超临界设备进行升温升压处理；
    S4、保持步骤S3升温升压处理的温度和压强充分反应，然后降压至大气压后将样品取出，完成低温处理。
  2. 根据权利要求1所述的方法，其特征在于，步骤S2中，氮氧气体的含量大于等于稳态超临界设备反应釜体积的10％，初始压强为5～25MPa。
  3. 根据权利要求2所述的方法，其特征在于，氮氧气体包括N 2O和NO，稳态超临界设备反应釜内的剩余气体包括O 2和N 2。
  4. 根据权利要求1所述的方法，其特征在于，步骤S3中，稳态超临界设备的温度为50～500℃，压强为10～100MPa。
  5. 根据权利要求1所述的方法，其特征在于，步骤S4中，在超临界状态下的反应时间为1～5h。
  6. 根据权利要求1至5中任一项所述的方法，其特征在于，低温处理后4H-SiC/SiO 2的界面态密度为1×10 11～1×10 12eV -1cm -2，击穿电场为10～13MV/cm，栅氧漏电流密度为1×10 -10～1×10 -8A·cm -2。
  7. 根据权利要求1所述基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法处理的电容器件在航空航天、探测传感和新能源汽车方面的应用。
  8. 一种基于超临界氮氧化合物改善4H-SiC/SiO 2界面的低温处理方法，其特征在于，将n型4H-SiC半导体材料标准清洗后进行高温氧化，然后放入反应釜中并充入氮氧气体；升温使 氮氧气体处于超临界状态，且压强随温度上升；达到50-500℃的固定处理温度和10～100MPa的压强后，将超临界状态持续直到反应时间结束；降温，将压力降至大气压后取出处理完的样品。
  9. 一种4H-SiC MOS电容器件，其特征在于，由权利要求1-7任意一项方法制备得到，其界面态密度为1×10 11～1×10 12eV -1cm -2，击穿电场为10～13MV/cm，栅氧漏电流密度为1×10 -10～1×10 -8A·cm -2。
  10. 一种由权利要求1-7任意一项方法制备的4H-SiC MOSFET器件。
PCT/CN2021/118871 2020-08-17 2021-09-16 一种基于超临界氮氧化合物改善4H-SiC/SiO2界面的低温处理方法及其应用 Ceased WO2022037709A1 (zh)

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