Co-doped N-type diamond and preparation method thereof, semiconductor material and semiconductor device

Abstract

The invention discloses a co-doped N-type diamond and a preparation method thereof, a semiconductor material and a semiconductor device. The beryllium atoms and the phosphorus atoms are co-doped in the diamond to form the co-doped N-type diamond, so that the carrier concentration, the mobility and the low resistivity are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor materials, and in particular to a co-doped N-type diamond and a preparation method thereof, a semiconductor material and a semiconductor device. Background Art

[0002] Silicon semiconductors have a small bandgap, low thermal conductivity, high dielectric constant, and intrinsic electron and hole mobilities of only 1350 and 480 cm 2 / V·s), making it difficult to use in high temperature, high frequency, high power, high voltage and very harsh environments. Single crystal diamond has high breakdown voltage, high hardness (~100GPa), high thermal conductivity (~2000W / m·k), ultra-wide bandgap (~5.5eV), low dielectric constant (~5.5), intrinsic electron and hole mobility up to 4500 and 3800cm 2 / V·s, making it the best known wide bandgap high-temperature semiconductor material, the most ideal semiconductor material, known as the "ultimate semiconductor". Effective n-type and p-type doping is the basis of semiconductor devices, but the controllable doping technology of single-crystal diamond has not yet made a breakthrough, which is also a huge obstacle for diamond devices to become practical. Diamond n-type doping is very difficult, and doping with elements such as nitrogen, oxygen, and sulfur cannot achieve ideal n-type conductivity. The doped atoms in the nitrogen-doped diamond layer have a deeper energy level in the bandgap (activation energy 1.7eV), making it a good insulator at room temperature and unable to achieve diamond n-type conductivity. Sulfur-doped diamond has a large formation energy, making it difficult to dope sulfur into diamond. In addition, the radius of sulfur atoms is much larger than that of carbon atoms. After being doped into diamond, it will cause a large amount of lattice distortion, thereby generating a large number of lattice defects, making most sulfur electrically inactive. The energy level of phosphorus doping is 0.57eV below the conduction band, and its solubility in diamond is higher than that of sulfur. It is currently an ideal n-type doping element. However, the large amount of hydrogen contained in the diamond during its growth process will produce a charge compensation effect that reduces the carrier concentration of phosphorus-doped diamond, and the defects and lattice dislocations inside the diamond also affect the phosphorus doping efficiency. The activation energy of phosphorus-doped diamond currently under study is large, which will hinder electron activation.

[0003] Therefore, it is necessary to develop a co-doped N-type diamond with high crystal quality, high carrier concentration and carrier mobility, and low resistivity. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the first aspect of the present invention provides a co-doped N-type diamond, wherein the co-doped N-type diamond has the characteristics of high carrier mobility and low resistivity.

[0005] The second aspect of the present invention further provides a method for preparing co-doped N-type diamond.

[0006] The third aspect of the present invention also provides a semiconductor material.

[0007] A fourth aspect of the present invention also provides a semiconductor device.

[0008] According to a first aspect of the present invention, an embodiment provides a co-doped N-type diamond, wherein the lattice structure of the co-doped N-type diamond includes carbon atoms, beryllium atoms and phosphorus atoms.

[0009] The co-doped N-type diamond according to the embodiment of the present invention has at least the following beneficial effects:

[0010] The invention co-dopes beryllium atoms and phosphorus atoms into diamond to form co-doped N-type diamond, thereby increasing carrier concentration and carrier mobility and reducing resistivity.

[0011] This is because the co-doping of beryllium and phosphorus in the present invention can not only reduce lattice distortion and improve the quality of diamond crystals, but also increase the solubility of donor impurities in the diamond film, and the interaction between the co-doped elements may change the position of the donor in the forbidden band, thereby reducing the activation energy of ionization.

[0012] According to some embodiments of the present invention, in the co-doped N-type diamond, the doping concentration of the beryllium atoms is 10 16 ~10 18 cm -3 .

[0013] According to some embodiments of the present invention, in the co-doped N-type diamond, the doping concentration of the phosphorus atoms is 10 16 ~10 19 cm -3 .

[0014] According to some embodiments of the present invention, the co-doped N-type diamond is single crystal diamond.

[0015] According to a second aspect of the present invention, an embodiment provides a method for preparing the co-doped N-type diamond as described in the first aspect of the present invention, comprising the following steps:

[0016] Using phosphorus source and beryllium source as doping elements, a co-doped N-type diamond is grown on the surface of a diamond intrinsic layer containing a diamond substrate by chemical vapor deposition; the conditions of the chemical vapor deposition method include:

[0017] The gas flow ratio of methane and hydrogen is 0.1% to 8%; the ratio of phosphorus to carbon in the mixed gas of gaseous phosphorus source and gaseous carbon source is 100 to 90000 ppm calculated by atomic ratio; and the substrate temperature is 870°C to 1200°C.

[0018] According to some embodiments of the present invention, the ratio of phosphorus (P) to carbon (C) in the mixture of the gaseous phosphorus source and the gaseous carbon source is 1000 to 10000 ppm, calculated by atomic ratio.

[0019] The preparation method according to the embodiment of the present invention has at least the following beneficial effects:

[0020] The invention uses phosphorus source and beryllium source as doping elements to grow co-doped N-type diamond on the surface of diamond intrinsic layer by chemical vapor deposition method; the method is simple and the prepared N-type diamond has high carrier mobility and low resistance.

[0021] According to some embodiments of the present invention, the chemical vapor deposition method includes a hot wire chemical vapor deposition method and a microwave chemical vapor deposition method.

[0022] According to some embodiments of the present invention, when the hot wire chemical vapor deposition method is selected, the distance between the hot wire and the surface of the diamond intrinsic layer on the stage is 1 to 15 mm.

[0023] According to some embodiments of the present invention, the number of the heating wires is 1 or more.

[0024] According to some embodiments of the present invention, when the hot wire chemical vapor deposition method is selected, the beryllium source is selected from a beryllium metal sheet or a metal mesh, and is located between the hot wire and the stage.

[0025] According to some embodiments of the present invention, the heating temperature of the beryllium source is 1000°C to 1150°C.

[0026] According to some embodiments of the present invention, the material of the heating wire is selected from tantalum wire, tungsten wire or niobium wire.

[0027] According to some embodiments of the present invention, the phosphorus source includes at least one of trimethylphosphine, dimethylphosphine, triethylphosphine, diethylphosphine, tert-butylphosphine, triphenylphosphine, phosphorus trifluoride, phosphorus pentafluoride, phosphorus trichloride or phosphorus pentachloride.

[0028] According to some embodiments of the present invention, the diamond intrinsic layer containing the diamond substrate is prepared by the following method:

[0029] In the presence of methane and hydrogen, a diamond intrinsic layer is grown on the surface of a diamond substrate by chemical vapor deposition.

[0030] According to some embodiments of the present invention, the diamond substrate is single crystal diamond.

[0031] According to some embodiments of the present invention, the crystal plane of the single crystal diamond is a (100) plane, a (111) plane or a (113) plane.

[0032] According to some embodiments of the present invention, before the growth of the diamond substrate, the step further includes mixing the diamond substrate with a mixed acid for treatment.

[0033] According to a third aspect of the present invention, an embodiment provides a semiconductor material, wherein the semiconductor material is composed of the co-doped N-type diamond described in the first aspect of the present invention.

[0034] According to a fourth aspect of the present invention, an embodiment provides a semiconductor device, wherein the semiconductor device is partially or entirely assembled from the co-doped N-type diamond described in the first aspect of the present invention.

[0035] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0037] Figure 1 This is a physical picture of the co-doped N-type diamond of Example 1 of the present invention;

[0038] Figure 2 This is a Raman test graph of the co-doped N-type diamond according to Example 1 of the present invention;

[0039] Figure 3 This is the XRD test diagram of the co-doped N-type diamond of Example 1 of the present invention;

[0040] Figure 4 Schematic diagram of the hot wire chemical vapor deposition device used in Example 1 of the present invention. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0042] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0043] In the description of the present invention, "several" means more than one, "many" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0044] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0045] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0046] Example 1

[0047] This example provides a co-doped N-type diamond, the lattice structure of which includes carbon atoms, beryllium atoms and phosphorus atoms, and the preparation method thereof is as follows:

[0048] In the experiment, the diamond intrinsic layer and the doped layer were grown using a HFCVD reactor (the schematic diagram of the hot wire chemical vapor deposition method is shown in Figure 4 shown).

[0049] The single crystal diamond substrate and mixed acid (H2SO4 and HNO3) were mixed and heated to 300°C to remove organic pollutants on the surface.

[0050] S1 Preparation of diamond intrinsic layer: Up to 150 insulating CVD single crystal diamonds of 10mm*10mm*0.5mm size can be placed on a molybdenum sample table with a diameter of 150mm for substrate. <111> The growth chamber was evacuated to ∼10° using a turbomolecular pump and a rotary pump. -4Pa, that is, the ultimate pressure. A double layer of 12 tantalum wires (99.95% purity, 0.5mm diameter, 300mm length) was used, and the hot wires were 8 mm apart from each other. These tantalum wires were resistively heated to 3000°C using a DC power supply. The distance between the hot wire and the diamond substrate was 4mm. Since the heat generated by the heated filaments maintains the sample stage temperature at 900°C, auxiliary heating can also be performed from the back of the sample stage and monitored by a thermocouple placed on the back of the substrate stage. When the total chamber pressure was 4kPa, the CH4 / H2 gas flow rate ratio was 3% and the growth rate was 1.0μm / h. The crystal quality was evaluated using cathodoluminescence (CL), etch pits, Raman spectroscopy, and X-ray diffraction rocking curve analysis. The impurity concentration was evaluated using secondary ion mass spectrometry (SIMS).

[0051] S2 Preparation of co-doped N-type diamond: Using an HFCVD system, phosphorus-beryllium co-doped diamond films were grown on diamond substrates and intrinsic epitaxial layers with (111) oriented surfaces. The carbon source and carrier gas were methane (CH4) and hydrogen (H2). A mixed gas diluted to 1000 ppm with H2 using trimethylphosphine (PMe3). The [CH4] / [H2] flow rate ratio was constant at 3%, and the ratio of phosphorus (P) / carbon (C) in the gaseous phosphorus source and gaseous carbon source mixed gas was 10000 ppm by atomic ratio, the total gas flow rate was 1000 sccm, and the ambient gas pressure was 4 kPa. A double-layer carbon filament was used as a hot filament, heated to 3000°C, and measured with a pyrometer and a power supply. The sample was placed on a Mo stage less than 4 mm below the hot filament. The stage temperature was maintained at 900°C with thermal radiation and auxiliary heating.

[0052] The beryllium source is selected from a metal mesh and clamped by a molybdenum metal clamp to ensure that it is located between the hot wire and the stage. The temperature of the beryllium source surface is controlled by controlling the distance between the beryllium metal mesh and the hot wire. The heat generated by thermal radiation makes the heating temperature of the beryllium source 1000°C.

[0053] Figure 1 The co-doped N-type diamond prepared in Example 1 of the present invention is shown in Figure 2. The co-doped N-type diamond prepared in Example 1 of the present invention is subjected to Raman testing, and the results are shown in Figure 2. Figure 2 As shown, from Figure 2 It can be seen that 1332cm -1 The half-height width of the first-order Raman shift of diamond at -1 .

[0054] The co-doped N-type diamond prepared in Example 1 of the present invention was subjected to an XRD test, and the results are as follows: Figure 3 As shown, from Figure 3 It can be seen that the half-height width of the XRD rocking curve of the diamond (400) crystal plane is 42.81 csec.

[0055] Embodiments 2 to 7

[0056] Examples 2 to 7 provide a series of co-doped N-type diamonds, the preparation methods of which are basically the same as those of Example 1, except that the parameters in Table 1 are set.

[0057] Table 1

[0058]

[0059] Comparative Example 1

[0060] This example provides an N-type diamond, and its preparation method is the same as that of Example 1, except that it does not contain a phosphorus source.

[0061] Comparative Example 2

[0062] This example provides an N-type diamond, and its preparation method is the same as that of Example 1, except that it does not contain a beryllium source.

[0063] Performance Testing

[0064] The N-type diamonds prepared in the examples of the present invention and the comparative examples were tested as follows; the results are shown in Table 2.

[0065] The concentration of phosphorus in diamond is determined by cathodoluminescence spectroscopy (CL) versus BE TO / FE TO ) was obtained by changing the phosphorus concentration (J. Appl. Phys. 101, 113701 (2007)).

[0066] The concentration of beryllium in diamond was measured by secondary ion mass spectrometry (SIMS).

[0067] The resistivity was measured by a four-probe method, and the carrier mobility was measured by a Hall effect instrument.

[0068] Table 2

[0069]

[0070] From the data in Table 1, the diamond prepared by simple phosphorus doping and beryllium doping has very low doping efficiency, high resistivity and low carrier mobility. The co-doped N-type diamond provided by the present invention has low resistivity and maintains high carrier mobility under high doping concentration.

[0071] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A co-doped N-type diamond, characterized in that: The lattice structure of the co-doped N-type diamond includes carbon atoms, beryllium atoms and phosphorus atoms.

2. The co-doped N-type diamond according to claim 1, characterized in that: In the co-doped N-type diamond, the doping concentration of the beryllium atoms is 10 16 ~10 18 cm -3 .

3. The co-doped N-type diamond according to claim 1 or 2, characterized in that: In the co-doped N-type diamond, the doping concentration of the phosphorus atoms is 10 16 ~10 19 cm -3 .

4. The co-doped N-type diamond according to claim 1 or 2, characterized in that: The co-doped N-type diamond is single crystal diamond.

5. A method for preparing the co-doped N-type diamond according to any one of claims 1 to 4, characterized in that: The steps include: Using phosphorus source and beryllium source as doping elements, a co-doped N-type diamond is grown on the surface of a diamond intrinsic layer containing a diamond substrate by chemical vapor deposition; the conditions of the chemical vapor deposition method include: The gas flow ratio of methane and hydrogen is 0.1% to 8%; the ratio of phosphorus to carbon in the mixed gas of gaseous phosphorus source and gaseous carbon source is 100 to 90000 ppm calculated by atomic ratio; and the substrate temperature is 870°C to 1200°C.

6. The preparation method according to claim 5, characterized in that: The chemical vapor deposition method includes a hot wire chemical vapor deposition method and a microwave chemical vapor deposition method.

7. The preparation method according to claim 5, characterized in that: The phosphorus source includes at least one of trimethylphosphine, dimethylphosphine, triethylphosphine, diethylphosphine, tert-butylphosphine, triphenylphosphine, phosphorus trifluoride, phosphorus pentafluoride, phosphorus trichloride or phosphorus pentachloride.

8. The preparation method according to claim 5, characterized in that: The diamond intrinsic layer containing the diamond substrate is prepared by the following method: In the presence of methane and hydrogen, a diamond intrinsic layer is grown on the surface of a diamond substrate by chemical vapor deposition.

9. A semiconductor material, characterized in that: The semiconductor material is composed of the co-doped N-type diamond according to any one of claims 1 to 4.

10. A semiconductor device, characterized in that: The semiconductor device is partially or entirely assembled from the co-doped N-type diamond according to any one of claims 1 to 4.

Images