JP4789035B2 - Semiconductor device using n-type diamond - Google Patents

Description

  The present invention is an n-type semiconductor of high conductivity and good crystallinity that can be used for electronic devices such as small high-power devices, high-power high-frequency devices, and radiation-resistant integrated circuits that are impossible with conventional semiconductors. The present invention relates to a semiconductor device using diamond, particularly n-type diamond in which donor atoms are effectively added to diamond.

In the Si-based semiconductors and gallium arsenide semiconductors currently used, the electric field strength inside the device increases due to the miniaturization and high density of the device, and heat generation during use becomes a problem. It is required to adapt to.
In contrast, diamond is a wide band gap semiconductor, has the highest electron and hole mobility, has a very high breakdown electric field, and generates very few electron-hole pairs at high temperatures and under radiation. Since it can be adapted to harsh environments, it can be used for devices for high power, high frequency operation, and high temperature operation. In order to realize such a diamond semiconductor device, a high-quality diamond crystal thin film is necessary.

Until now, low-resistance p-type semiconductor diamond could be easily fabricated by boron doping, but for low-resistance n-type semiconductor diamond, many manufacturing methods including a doping method to CVD diamond have been studied. However, it was actually difficult to obtain a high-quality semiconductor diamond crystal thin film.
For example, it has been reported that diamond doped with nitrogen has a low activation energy and thus becomes an insulator at room temperature (see Non-Patent Document 1). Furthermore, although an n-type diamond crystal thin film doped with phosphorus has been reported, the electrical resistance is too high to be suitable for practical use (see Non-Patent Document 2).

  An attempt to obtain an n-type diamond thin film from methane and hydrogen sulfide by microwave plasma CVD has also been reported (see Patent Document 1). However, as is clear from Tables 1 and 2 of the publication, the electron mobility of the n-type semiconductor diamond thin film produced by the microwave plasma CVD method was produced by the ultrahigh pressure method shown in Table 2. Compared to the electron mobility of the n-type semiconductor diamond single crystal, it shows an abnormally large value while having the same sulfur concentration. That is, this n-type semiconductor diamond thin film has many defects and cannot be applied to semiconductor electronic devices.

As for the production of phosphorus-doped diamond by microwave plasma CVD, phosphine (PH ₃ ) is introduced into the reaction gas of hydrogen and hydrocarbon, phosphine is decomposed in microwave plasma, and phosphorus is doped, and A method of doping phosphine by decomposing phosphine under high temperature or ultraviolet irradiation is known.
However, according to this microwave plasma CVD method, phosphorus in a state of being bonded to hydrogen is doped into diamond, so that phosphorus does not serve as an electron supplier, and even if phosphorus is doped, it is n-type. Since semiconductor diamond has low carrier mobility and deep levels, an n-type semiconductor of a quality applicable to semiconductor electronic devices has not been obtained.
As described above, in the CVD method, various methods for producing an n-type semiconductor diamond crystal thin film have been reported so far, but a quality of a level applicable to a semiconductor electronic device has not been obtained.

  Furthermore, there is also known a method of accelerating phosphorus ions into diamond. However, in this method, phosphorus having a mass larger than that of carbon is implanted, so that defects are generated in diamond and phosphorus is bonded to carbon. Therefore, it is difficult to form a bond in the diamond lattice, and a high-quality n-type semiconductor diamond has not been obtained.

Also known as a phosphorus doping method for diamond without using plasma is a chemical transport reaction method in which graphite and red phosphorus are placed in the reaction system and evaporated in the system to synthesize diamond, and then phosphorus is doped into it. .
However, because of the difference in the reaction rate and evaporation rate between graphite and red phosphorus, it becomes difficult to control the phosphorus concentration, and a high-quality n-type semiconductor cannot be obtained.

  Recently, an n-type diamond semiconductor in which pentavalent or higher valent atoms are added as donor atoms has also been proposed (see Patent Document 2). However, an n-type semiconductor diamond that can be applied to a semiconductor electronic device to which sulfur is added has not been realized yet, and its manufacturing method is a problem.

JP-A 63-302516 Japanese Patent Laid-Open No. 10-194889 Mat. Res. Soc. Symp. Proc. 162, 3-14 (1990) Mat. Res. Soc. Symp. Proc. 162, 23-34 (1990)

  SUMMARY OF THE INVENTION The present invention solves such problems in the prior art and provides a semiconductor device using n-type diamond having perfect crystallinity applicable to a semiconductor device.

In order to achieve the above object, in the semiconductor device using the n-type diamond of the present invention, the impurity atom of the n-type diamond is a sulfur atom, and this sulfur atom forms a single donor level of 0.38 eV. It is characterized by.
In the semiconductor device using the n-type diamond of the present invention, the impurity atom of the n-type diamond is a sulfur atom, and this sulfur atom forms a single donor level of 0.38 eV, and the room temperature of the n-type diamond is low. The electron carrier concentration at is 1.4 × 10 ¹³ cm ⁻³ or more.
In the above configuration, the electron mobility of the n-type diamond is preferably 580 cm ² V ⁻¹ · s ⁻¹ or more at room temperature.
The electron mobility preferably has T ^-3/2 dependency in a temperature (T) region above room temperature. The half width of the Raman spectrum is preferably 2.6 cm ⁻¹ or less.
In addition, free exciton and exciton emission are observed, and a clear Kikuchi pattern is observed in reflected electron diffraction.
The semiconductor device has a pn junction. This semiconductor device is preferably a power device or a high-frequency device.

  According to the semiconductor device using the n-type diamond having the above structure, the n-type semiconductor diamond having n-type conductivity in which carriers are supplied from a single donor level, high electron mobility, and few crystal defects. Since it is configured, it is possible to industrially manufacture a semiconductor electronic device using a semiconductor diamond thin film, and a small high-power device, a high-power high-frequency device, a high-temperature operating device, and the like can be realized.

  According to the present invention, it is possible to industrially manufacture a semiconductor electronic device using a semiconductor diamond thin film, and it is possible to realize manufacture of a small high-power device, a high-output high-frequency device, a high-temperature operating device, and the like.

Hereinafter, the best example in the manufacturing method of the n-type diamond diamond used for the semiconductor device of the present invention will be described in detail with reference to the drawings.
The n-type semiconductor diamond growth method may be a growth method that uses any one of electricity, heat, and light energy according to the method for activating the source gas, but in this embodiment, electric energy and heat energy are used. An epitaxial growth method using a microwave plasma CVD (chemical vapor deposition) apparatus is used.
First, the pretreatment of the epitaxial growth substrate of this embodiment will be described. In this substrate pretreatment, (1) the surface of a diamond (100) -oriented substrate is <100 in the plane in which the surface normals are the <100> direction and the <010> direction or the <100> direction and the <001> direction. > Mechanical polishing is performed so as to be inclined at any angle (inclination angle) in the range of 1.5 to 6 degrees with respect to the direction, and (2) the inclined substrate is exposed to hydrogen plasma to obtain a surface. Is characterized by smoothing.

The mechanical polishing of (1) uses diamond abrasive grains having a particle size of 0.5 μm or less.
The surface smoothing treatment of (2) uses a microwave plasma apparatus described below, and a microwave output of 2.45 GHz 200 to 1200 W, a hydrogen pressure of 10 to 50 Torr, a substrate temperature of 700 to 1200 ° C., and a treatment time of 0. Perform in 5-5 hours. In addition, this surface smoothing process is possible also by exposing to the oxidation flame of combustion flames, such as acetylene.

FIG. 1A shows the above-described substrate pretreatment, that is, in the plane in which the surface normal of the diamond (100) substrate is the <100> direction and the <010> direction or the <100> direction and the <001> direction. The state of the surface of the inclined substrate mechanically polished so as to be inclined at any angle (inclination angle) in the range of 1.5 to 6 degrees with respect to the <100> direction is shown by a schematic cross-sectional view.
As shown in this figure, the inclined substrate surface has a predetermined inclination angle (α) set at the time of mechanical polishing on the envelope surface, but when viewed microscopically, there are many irregularities on the atomic order.

FIG. 1B shows the substrate pretreatment, that is, the inclined substrate is exposed to the hydrogen plasma to perform the smoothing treatment, and the surface state after the smoothing treatment is shown by a schematic sectional view. is there.
As shown in the figure, the surface of the substrate is smoothed in the atomic order by the smoothing process, and the (100) plane is a stepped surface in the atomic layer order.

In order to achieve the above object, the semiconductor device using the n-type diamond of the present invention is an n-type diamond in which the impurity atom is a sulfur atom, and this sulfur atom forms a single donor level of 0.38 eV. In addition, the temperature dependence of electron mobility has a T ^−3/2 dependence in a temperature (T) region above room temperature , and has a single Raman spectrum with a half-width of 2.6 cm ⁻¹ , and exciton emission is Observed and characterized in that a clear Kikuchi pattern is observed in reflected electron diffraction.
In the above structure, preferably, at room temperature, an electron carrier concentration is 1.4 × 10 ¹³ cm ⁻³ or more, and the electron mobility is 580 cm ² V ⁻¹ · s ⁻¹ or more.
The semiconductor device has a pn junction. This semiconductor device is preferably a power device or a high-frequency device.
In the method of manufacturing a semiconductor device using n-type diamond according to the present invention, a diamond substrate is made into a tilted substrate by mechanical polishing, and the surface of the tilted substrate is subjected to a smoothing process in which the tilted substrate is exposed to hydrogen plasma. Forming a smooth surface in atomic order linked in steps in layer order, while exciting a raw material gas consisting of volatile hydrocarbons, sulfur compounds and hydrogen gas with microwave plasma to maintain a predetermined substrate temperature, An n-type semiconductor diamond is epitaxially grown on a smooth surface in atomic order.
In the above configuration, the diamond substrate is preferably a diamond (100) plane orientation substrate.
The tilted substrate is preferably a diamond (100) plane orientation substrate, and the surface normal of the substrate is <100> and <010> directions, or <100> in a plane formed by <100> and <001> directions. The tilted substrate is mechanically polished so as to tilt at any angle in the range of 1.5 to 6 degrees with respect to the direction.
In the smoothing treatment of exposing to hydrogen plasma, the inclined substrate is preferably subjected to microwave hydrogen plasma having an output of 200 to 1200 W, a frequency of 2.45 GHz, and a hydrogen pressure of 10 to 50 Torr at a substrate temperature of 700 to 1200 ° C. and 0.5 to It is exposed for 5 hours to smooth the substrate surface in the atomic layer order.
The predetermined substrate temperature is preferably set to 700 ° C. to 1100 ° C., more preferably 830 ° C.

FIG. 2B is an AFM photograph of the surface of the inclined substrate after the smoothing process (2) is performed.
From this figure, it can be seen that the level difference seen in FIG. 2A is reduced, and there are no fine streak marks due to the abrasive grains, and the surface is smoothed in atomic order. That is, as shown in the schematic diagram of FIG. 1B, the surface of the substrate is smoothed in the atomic order by the surface smoothing treatment of (2) above, and the (100) plane is in the atomic layer order. It becomes the surface which continued in steps.

FIG. 3A shows a microwave using a raw material gas obtained by diluting methane gas and hydrogen sulfide gas with hydrogen gas, which will be described in detail below, on the substrate that has been subjected to the substrate pretreatment of (1) and (2) above. It is an optical microscope photograph of the surface of the 1-micrometer-thick n-type diamond thin film epitaxially grown by plasma CVD method. FIG. 3B is an optical micrograph of the surface of the n-type diamond thin film epitaxially grown on the (100) substrate that is not subjected to the substrate pretreatment of (1) and (2) above (except for the substrate pretreatment). Produced under the same conditions as above).
As shown in FIG. 3A, the surface of the n-type diamond thin film epitaxially grown on the substrate that has been subjected to the substrate pretreatment of the above (1) and (2) is very flat and flat on the atomic order. I understand that. In addition, as will be described in detail below, this n-type diamond thin film is a very high complete crystal in the measurement for evaluating crystallinity, for example, the temperature dependence of mobility, exciton emission, or Raman spectrum. Showing sex.

On the other hand, as shown in FIG. 3B, a triangular pyramid-shaped twin crystal grows on the surface of the n-type diamond thin film epitaxially grown on the substrate not subjected to the substrate pretreatment of the above (1) and (2). In addition, it can be seen that the surface has severe irregularities reflecting polishing marks. In addition, this n-type diamond thin film does not exhibit high complete crystallinity as in the case of the n-type diamond thin film epitaxially grown on the substrate pretreated substrates (1) and (2) in the measurement of crystallinity. .
In addition, as shown in FIG. 1C, the substrate surface in the case where the surface is parallel to the (100) plane, that is, mechanically polished at an inclination angle of 0 and subjected to the smoothing process of (2), is the (100) plane. In the atomic layer order, the surfaces of the n-type diamond thin film epitaxially grown on the surface of the n-type diamond thin film epitaxially grown on the (100) plane are formed as twins as shown in FIG. Also, good results cannot be obtained in the above-described measurement for evaluating crystallinity.

  As described above, as the pretreatment of the epitaxial growth substrate, (1) the surface normal of the diamond (100) orientation substrate is the <100> direction and the <010> direction or the <100> direction and the <001> direction. An inclined substrate that is mechanically polished so as to incline at any angle (inclination angle) in the range of 1.5 to 6 degrees with respect to the <100> direction as a reference in the plane formed by (2), By subjecting the substrate to hydrogen plasma and smoothing the surface, the surface is smoothed in the atomic order, and a surface in which the (100) planes are connected stepwise in the atomic layer order is obtained. By epitaxial growth, n-type diamond with good crystallinity can be epitaxially grown.

Next, the microwave plasma CVD apparatus used in this example will be described. FIG. 4 is a schematic configuration diagram of a microwave plasma CVD apparatus used in this embodiment.
Referring to FIG. 4, a microwave plasma CVD apparatus 10 used in the present embodiment includes, for example, a microwave generator 1 of 2.45 GHz, an isolator / power monitor 3, and a tuner 5, and is irradiated with microwaves. A reaction tube 7, a vacuum pump (not shown) for evacuating the reaction tube 7, a gas supply line 9 for switching and supplying a mixed gas or a purge gas as a raw material gas to the reaction tube 7, and a plurality of optical components Windows 11, 11, a substrate holder 13 provided in the reaction tube, and a temperature control system 17 for heating or cooling the substrate 15 installed on the substrate holder 13, and gas is supplied onto the substrate 15. A microwave plasma 19 is generated. The substrate temperature is monitored with an optical pyrometer.
Next, conditions for epitaxial growth of n-type semiconductor diamond by microwave plasma CVD will be described. This growth condition varies depending on the raw material, temperature, pressure, gas flow rate, impurity addition amount, substrate area, and the like.

FIG. 5 is a diagram showing the growth conditions of sulfur-doped semiconductor diamond homoepitaxy in this example. Referring to FIG. 5, in this embodiment, the reaction gas uses a mixed gas of methane / hydrogen sulfide / hydrogen as a raw material gas, but volatile hydrocarbons such as alkane and alkene / sulfur compound gas / hydrogen. Can be used as a raw material gas. Hydrocarbon is used as a source of carbon, which is a constituent element of diamond, sulfur compound gas is used as a source of donor atoms, and hydrogen is used as a carrier gas.
For example, methane, ethane, or propane is used as an alkane, and ethylene or propylene is used as an alkene. However, as a volatile hydrocarbon, methane can easily minimize the carbon supply of diamond constituent elements. Most preferred.

Examples of the sulfur compound include inorganic sulfur compounds such as hydrogen sulfide (H ₂ S) and carbon disulfide (CS ₂ ), and organic sulfur compounds such as lower alkyl mercaptan, with hydrogen sulfide being most preferred.
Therefore, it is preferable to use methane / hydrogen sulfide / hydrogen as the mixed gas. The methane concentration in the mixed gas is 0.1% to 5%, preferably 0.5% to 3.0%. The concentration of hydrogen sulfide in the mixed gas should be 1 ppm to 2000 ppm, preferably 5 ppm to 200 ppm.

In this embodiment, the methane concentration is 1% and the hydrogen sulfide is 10 to 100 ppm. As the concentration of hydrogen sulfide increases, the carrier concentration increases. In this hydrogen sulfide concentration range, the mobility is most preferably 50 ppm since the addition amount of hydrogen sulfide is 50 ppm.
The total gas flow rate depends on the scale of the apparatus, for example, the volume of the reaction tube section, the supply gas flow rate, the displacement, etc., but in this embodiment it is 200 ml / min.

  The gas flow rate is controlled by a mass flow controller corresponding to each gas type. The amount of hydrogen sulfide added is, for example, a 100 ppm hydrogen sulfide / hydrogen mixed gas cylinder, diluted with carrier hydrogen, and the flow rate is controlled by the mass flow controller. It is controlled to the ratio of the added amount.

In this embodiment, a 100 ppm hydrogen sulfide / hydrogen mixed gas cylinder is used. In this embodiment, since the hydrogen sulfide concentration is set to 50 ppm, when the total flow rate is 200 ml / min, the carrier hydrogen gas is set to 100 ml / min, and when 100 ml / min is flowed from the 100 ppm hydrogen sulfide / hydrogen mixed gas cylinder as a whole, The hydrogen sulfide concentration can be set to 50 ppm.
In the microwave plasma CVD, the atmospheric pressure is about 30 to 60 Torr, and in this embodiment, the pressure is set to 40 Torr. In microwave discharge, glow discharge is maintained at a relatively high pressure.

  The temperature of the substrate on which the diamond is deposited is 700 ° C. to 1100 ° C., but in this embodiment it is 830 ° C. Moreover, although Ib diamond was used as a substrate diamond, it is not limited to this type of diamond, and may be Ia or II type. Further, in the present embodiment, diamond is homoepitaxially grown on the (100) plane, but is not limited to the (100) plane, and may be, for example, the (111) plane or the (110) plane.

Next, a manufacturing process of the n-type semiconductor diamond in this example will be described.
First, as a pretreatment for the substrate for epitaxial growth, diamond abrasive grains having a grain size of 0.5 μm or less are used, and the surface of the diamond (100) oriented substrate is directed to the <100> direction and the <010> direction. Alternatively, an inclined substrate that has been mechanically polished so as to be inclined at any angle (inclination angle) in the range of 1.5 to 6 degrees with respect to the <100> direction in a plane formed by the <100> direction and the <001> direction. This tilted substrate is exposed to hydrogen plasma with a microwave output of 200 to 1200 W at 2.45 GHz and a hydrogen pressure of 10 to 50 Torr using the microwave plasma apparatus described above, and the substrate temperature is 700 to 1200 ° C. The surface is smoothed for a treatment time of 0.5 to 5 hours. In addition, this surface smoothing process is possible also by exposing to the oxidation flame of combustion flames, such as acetylene.

  Next, the substrate is cleaned, placed on a substrate holder, and hydrogen purge is repeated several times from the gas supply line to remove nitrogen and oxygen in the vacuum vessel. Next, while the substrate holder is heated, the substrate surface temperature is controlled to be 830 ° C. and the pressure is controlled to 40 Torr. The substrate surface temperature is measured with an optical pyrometer, for example.

Next, microwave discharge is performed under a pressure control of 40 Torr and the purge hydrogen gas is switched to a mixed gas diluted with hydrogen of 1% methane / 50 ppm hydrogen sulfide in the gas supply line and introduced into the reaction tube at 200 ml / min. Plasma is generated above the substrate. This plasma flow is supplied to the diamond substrate, and the diamond thin film grows epitaxially.
When the predetermined film thickness is reached, the gas supply line is switched to hydrogen purge and the microwave discharge is stopped to stop or cool the substrate heating.
Finally, when the temperature returns to room temperature, the diamond substrate is removed from the substrate holder of the reaction tube that has returned to normal pressure.

An electrode whose ohmic characteristics were confirmed at a measurement temperature of 250 to 550 K was formed on the thus produced diamond crystal thin film. The diamond crystal thin film thus produced exhibits a negative Hall coefficient at a measurement temperature of 250 to 550 K, has a high mobility at room temperature of 580 cm ² / V · s, and has a backscattered electron diffraction (RHEED) A clear Kikuchi pattern can be observed, and the crystallinity of the crystalline thin film is extremely high.

  As is clear from the above description, the n-type semiconductor diamond used in the semiconductor device of the present invention can be manufactured with high mobility and good crystallinity.

Next, the characteristics of the n-type semiconductor diamond thus manufactured will be described in detail.
FIG. 6 is a diagram showing the temperature dependence of the carrier concentration of the n-type semiconductor diamond according to the present embodiment.
As can be seen from FIG. 6, the carrier concentration increases from 10 ¹² to 10 ¹⁶ cm ^{−3 with} increasing temperature, and the conductivity of the diamond thin film is 1.3 × 10 ⁻³ Ω ⁻¹ cm ⁻¹ at room temperature. . As can be seen from this figure, the carrier concentration shows a complete exponential dependence on the reciprocal of temperature, indicating that carriers are supplied only from a single donor level. As can be seen from FIG. 6, the activation energy of the donor level is 0.38 eV.
That is, the n-type semiconductor diamond of the present invention is an n-type semiconductor diamond in which sulfur (S) atoms form a single donor level with an activation energy of 0.38 eV.

FIG. 7 is a diagram showing the temperature dependence of the mobility by the Hall coefficient measurement of the n-type semiconductor diamond of this example.
In the measurement temperature 250-550K, all show a negative Hall coefficient.
As is apparent from FIG. 7, the carrier concentration at room temperature is 1.4 × 10 ¹³ cm ⁻³ and the mobility is 580 cm ² / V · s.
FIG. 8 is a diagram showing the temperature dependence of the mobility of n-type semiconductor diamond grown at 780 ° C. by measuring the Hall coefficient. The growth conditions other than the substrate temperature are the same, but since the substrate temperature is low, the amount of sulfur (S) incorporated into the crystal is small.
In the example shown in FIG. 8, the mobility is 980 cm ² / V · s. Therefore, the n-type semiconductor diamond of the present invention exhibits extremely high mobility even when the amount of sulfur doped is small.
The electron mobility of type IIa diamond is estimated to be about 2000 cm ² V ⁻¹ · s ⁻¹ . However, according to the manufacturing method of this example, the crystallinity can be made extremely well. A mobility of 10 ³ cm ² V ⁻¹ · s ⁻¹ is also possible.

FIG. 9 is a diagram showing a mobility comparison between the sulfur (S) -doped n-type semiconductor diamond of this example and the conventional phosphorus (P) -doped n-type semiconductor diamond.
In FIG. 9, □ indicates the data of the S-doped n-type semiconductor diamond according to the present invention when the growth temperature is 780 ° C. and the ◯ indicates 830 ° C. The black circles and chain lines indicate the conventional P-doped n-type semiconductor. Diamond data.
Conventional P-doped n-type semiconductor diamond has a mobility of about 10 cm ² / V · s at room temperature and a maximum value of about 30 cm ² / V · s (Diamond and Related Materials 7 (1998) 540-544, S. Koizumi et al).
On the other hand, in the S-doped n-type semiconductor diamond of this example, the mobility is about 600 cm ² / V · s or more as described above, and the mobility is extremely high.
Furthermore, the sulfur (S) doped n-type semiconductor diamond according to the production method of the present invention, contrary to the temperature dependence shown when the temperature characteristics of the mobility is large crystal defects decreases as a high temperature, T ^-3 Shows ^{/ 2} dependency.
This temperature characteristic indicates that the carrier scattering process is predominantly due to phonons, and is observed only in a single crystal having high perfect crystallinity. Therefore, the sulfur (S) -doped n-type semiconductor diamond of this example has very few crystal defects. Therefore, the source of carriers is not due to crystal defects or the like but is due to dopant atoms, so that it can be used as a semiconductor electronic device. It turns out that it has.

FIG. 10 is a diagram showing a Raman spectrum of the n-type semiconductor diamond of this example. As apparent from FIG. 10, the wave number is nothing no peak other than the peak of 1333 cm ^-1, the half width is very narrow and approximately 2.6 cm ^-1. Therefore, the n-type semiconductor diamond of this example has extremely high crystallinity. Although not shown, the wave number of the n-type semiconductor diamond epitaxially grown without performing the substrate pretreatment is about 6 cm ⁻¹ .

  FIG. 11 is a diagram showing spectra of free exciton emission and bound exciton emission of the n-type semiconductor diamond of this example. As is apparent from FIG. 11, in the n-type semiconductor diamond of this example, free exciton emission (FE) near 235 nm and bound exciton emission (BE) near 238 nm are observed. This indicates in particular that doped sulfur is present at the lattice points of the diamond lattice and forms a complete donor level within the band gap of the diamond crystal. Moreover, in the n-type semiconductor diamond epitaxially grown without performing the substrate pretreatment, free exciton light emission and bound exciton light emission are not observed.

  FIG. 12A shows a secondary electron microscope (SEM) photograph, and FIG. 12B shows a backscattered electron diffraction (RHEED) pattern. As is clear from FIG. 12 (a), the surface of the n-type semiconductor diamond of this example is very smooth. As is clear from FIG. 12B, a very clear Kikuchi pattern is generated, and it can be confirmed that the crystallinity is extremely high.

FIG. 13 is a diagram showing an atomic concentration profile by secondary ion mass spectrometry (SIMS) in the n-type semiconductor diamond of this example. From FIG. 13, sulfur (S) is doped at a constant concentration in the n-type semiconductor diamond of this example, and this sulfur (S) is at least 10 ¹³ cm ⁻³ or more of the SIMS detection limit. I understand.

As is clear from the above description, the n-type semiconductor diamond produced in this example has n-type conductivity in which carriers are supplied from a single donor level, and has few crystal defects and high mobility. Therefore, a pn junction having excellent characteristics can be formed by combining with a conventional p-type semiconductor diamond manufacturing technique.
Therefore, according to the present invention, it is possible to industrially manufacture a semiconductor electronic device using a semiconductor diamond thin film, and a small high-power device, a high-output high-frequency device, a high-temperature operating device, and the like can be realized.

  In addition, the present embodiment is an exemplary embodiment of the present invention, and various modifications, omissions, and additions can be made in the embodiment without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the embodiments but should be understood to include the scope defined by the elements recited in the claims and the equivalents thereof.

It is a schematic diagram which shows the substrate surface state by the board | substrate pretreatment of a present Example. It is an atomic force microscope (AFM) photograph of the substrate surface shape by the substrate pretreatment of this example. It is the optical microscope photograph which compared the surface shape at the time of carrying out the epitaxial growth of the sulfur dope n-type semiconductor diamond to the board | substrate which performed the board | substrate pre-processing of a present Example, and the board | substrate which does not give. It is a schematic block diagram of the microwave plasma CVD apparatus used in the present Example. It is a figure which shows the sulfur dope n-type semiconductor diamond homoepitaxy growth conditions of a present Example. It is a figure which shows the temperature dependence of the carrier concentration of the sulfur dope n-type semiconductor diamond of a present Example. It is a figure which shows the temperature dependence of the mobility by the Hall coefficient measurement of the sulfur dope n-type semiconductor diamond of a present Example. It is a figure which shows the temperature dependence of the mobility by the Hall coefficient measurement of the sulfur dope n-type semiconductor diamond grown with the substrate temperature of 780 degreeC of a present Example. It is a figure which shows the comparison of the mobility of the sulfur dope n type semiconductor diamond of a present Example, and the conventional phosphorus dope n type semiconductor diamond. It is a figure which shows the Raman spectrum of the sulfur dope n-type semiconductor diamond of a present Example. It is a figure which shows the spectrum of the free exciton light emission and the bound exciton light emission of the sulfur dope n-type semiconductor diamond of a present Example. It is a figure which shows the crystallinity of the sulfur dope n-type semiconductor diamond of a present Example, (a) shows a secondary electron microscope (SEM) image, (b) has shown the reflection electron beam diffraction (RHEED) pattern. It is a figure which shows the profile of the atomic concentration of the secondary ion mass spectrometry (SIMS) in the sulfur dope n-type semiconductor diamond of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microwave generator 3 Monitor 5 Tuner 7 Reaction tube 9 Gas supply line 10 Microwave plasma CVD apparatus 11 Optical window 13 Substrate holder 15 Substrate 17 Temperature control system 19 Microwave plasma α Inclination angle

Claims (11)

In n-type diamond , the impurity atom is a sulfur atom, the sulfur atom forms a single donor level of 0.38 eV , and the temperature dependence of electron mobility is room temperature or higher (T) and has a T ^-3/2 dependence in the region has a single Raman spectrum half width 2.6 cm ^-1, exciton emission is observed, clear Kikuchi pattern is observed in the reflected electron beam diffraction A semiconductor device using n-type diamond. At room temperature, the carrier concentration of the electron is not less 1.4 × ¹⁰ 13 ^{cm -3} or more and the electron mobility, and wherein the at 580cm ² V ^-1 · ^{s -1} or higher, according to claim 1 A semiconductor device using the n-type diamond described in 1.   The semiconductor device using n-type diamond according to claim 1, wherein the semiconductor device has a pn junction.   The semiconductor device using n-type diamond according to claim 1 or 2, wherein the semiconductor device is a power device.   The semiconductor device using n-type diamond according to claim 1, wherein the semiconductor device is a high-frequency device. The diamond substrate is made into a tilted substrate by mechanical polishing, and the surface of the tilted substrate is smoothed by exposing it to hydrogen plasma so that the surface of the tilted substrate becomes a smooth surface in the atomic order in which (100) planes are connected in steps in the atomic layer order. A source gas composed of volatile hydrocarbon, sulfur compound and hydrogen gas is excited by microwave plasma, and n-type semiconductor diamond is epitaxially grown on a smooth surface in the atomic order while maintaining a predetermined substrate temperature. A method for producing a semiconductor device using n-type diamond. 7. The method of manufacturing a semiconductor device using n-type diamond according to claim 6, wherein the diamond substrate is a diamond (100) plane orientation substrate. The tilted substrate is a diamond (100) plane orientation substrate, and the surface normal of the substrate has a <100> direction in a plane formed by a <100> direction and a <010> direction, or a <100> direction and a <001> direction. 7. The method of manufacturing a semiconductor device using n-type diamond according to claim 6, wherein the substrate is an inclined substrate mechanically polished so as to be inclined at any angle in a range of 1.5 to 6 degrees as a reference. In the smoothing treatment of exposing the hydrogen plasma, the inclined substrate is subjected to microwave hydrogen plasma having an output of 200 to 1200 W, a frequency of 2.45 GHz, and a hydrogen pressure of 10 to 50 Torr at a substrate temperature of 700 to 1200 ° C. and 0.5 to 5%. 7. The method of manufacturing a semiconductor device using n-type diamond according to claim 6, wherein said substrate is exposed to time to smooth the substrate surface in an atomic layer order. The method of manufacturing a semiconductor device using n-type diamond according to claim 6, wherein the predetermined substrate temperature is set to 700 ° C to 1100 ° C. The method of manufacturing a semiconductor device using n-type diamond according to claim 10, wherein the predetermined substrate temperature is set to 830 ° C.