WO2020261356A1 - 半導体膜 - Google Patents

半導体膜 Download PDF

Info

Publication number
WO2020261356A1
WO2020261356A1 PCT/JP2019/025044 JP2019025044W WO2020261356A1 WO 2020261356 A1 WO2020261356 A1 WO 2020261356A1 JP 2019025044 W JP2019025044 W JP 2019025044W WO 2020261356 A1 WO2020261356 A1 WO 2020261356A1
Authority
WO
WIPO (PCT)
Prior art keywords
film
semiconductor film
substrate
void
layer
Prior art date
Application number
PCT/JP2019/025044
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
守道 渡邊
福井　宏史
吉川　潤
Original Assignee
日本碍子株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本碍子株式会社 filed Critical 日本碍子株式会社
Priority to PCT/JP2019/025044 priority Critical patent/WO2020261356A1/ja
Priority to JP2021528678A priority patent/JPWO2020261356A1/ja
Publication of WO2020261356A1 publication Critical patent/WO2020261356A1/ja

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/40—Oxides
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides

Definitions

  • the present invention relates to a semiconductor film, and more particularly to an ⁇ -Ga 2 O 3 system semiconductor film containing a void and containing a halogen element in the void.
  • gallium oxide (Ga 2 O 3 ) has been attracting attention as a material for semiconductors.
  • Gallium oxide is known to have five crystal forms of ⁇ , ⁇ , ⁇ , ⁇ and ⁇ .
  • ⁇ -Ga 2 O 3 which is a semi-stable phase has a band gap of 5.3 eV. It is very large and is expected as a material for power semiconductors.
  • Patent Document 1 discloses a semiconductor device including a base substrate having a corundum-type crystal structure, a semiconductor layer having a corundum-type crystal structure, and an insulating film having a corundum-type crystal structure, and a sapphire substrate.
  • An example in which an ⁇ -Ga 2 O 3 film is formed as a semiconductor layer is described above.
  • Patent Document 2 describes an n-type semiconductor layer containing a crystalline oxide semiconductor having a corundum structure as a main component, a p-type semiconductor layer containing an inorganic compound having a hexagonal crystal structure as a main component, and an electrode.
  • a semiconductor device comprising the above is disclosed.
  • an ⁇ -Ga 2 O 3 film having a corundum structure which is a semi-stable phase as an n-type semiconductor layer is formed on a c-plane sapphire substrate, and a hexagonal crystal structure is used as a p-type semiconductor layer. It is disclosed that a diode is produced by forming an ⁇ -Rh 2 O 3 film having.
  • Patent Document 3 discloses that an ⁇ -Ga 2 O 3 film having few cracks is produced.
  • Patent Document 4 discloses that an ⁇ -Ga 2 O 3 film having reduced cracks is produced by including voids when the epitaxial film is formed.
  • Patent Document 5 discloses an example in which a crystalline oxide semiconductor film having a large area and substantially free of cracks is obtained by using a film-forming base substrate on which two or more oxide layers are formed. Has been done. However, it is necessary to form a plurality of layers on the base substrate, which complicates the work and is disadvantageous in terms of cost. Further, when the film produced by this method is separated from the film-forming base substrate to be self-supporting, or when it is reprinted on another support substrate, cracks and the like are still likely to occur. Therefore, an ⁇ -Ga 2 O 3 semiconductor film and a method for producing the same are desired, in which cracks and the like are less likely to occur not only at the time of film formation but also after self-supporting.
  • An object of the present invention is to provide an ⁇ -Ga 2 O 3 system semiconductor film in which cracks are reduced and cracks are less likely to occur.
  • the present inventors have now made the ⁇ -Ga 2 O 3 system semiconductor film contain a void and contain a halogen element in the void, thereby not only reducing cracks during film formation but also forming the semiconductor film. It was found that the film is less likely to crack when it is separated from the substrate for film formation and becomes self-supporting, and even after it is self-supporting.
  • the semiconductor film of the present invention is a semiconductor film having a corundum-type crystal structure composed of an ⁇ -Ga 2 O 3 or ⁇ -Ga 2 O 3 system solid solution.
  • the semiconductor film contains a void, and the void contains a halogen element. It is a thing.
  • Patent Document 4 discloses an example in which a voided ⁇ -Ga 2 O 3 thin film is formed using an aqueous solution of gallium bromide and a solution of hydrobromic acid.
  • halogen elements such as bromine were not detected, and the crack suppressing effect as in the present invention could not be obtained.
  • Patent Document 4 incorporates halogen elements into the voids due to the fact that the void formation method is different from that of the present application and the formation conditions of the ⁇ -Ga 2 O 3 thin film are different. It is presumed that it was not done.
  • the semiconductor film of the present embodiment has a corundum-type crystal structure composed of an ⁇ -Ga 2 O 3 or ⁇ -Ga 2 O 3 system solid solution.
  • a semiconductor film is referred to as an ⁇ -Ga 2 O 3 system semiconductor film.
  • ⁇ -Ga 2 O 3 belongs to a trigonal crystal group and has a corundum-type crystal structure.
  • the ⁇ -Ga 2 O 3 system solid solution is a solid solution of other components in ⁇ -Ga 2 O 3 , and the corundum type crystal structure is maintained.
  • Other components include, for example, oxides having a corundum-type crystal structure such as ⁇ -Al 2 O 3 , ⁇ -In 2 O 3 , ⁇ -Cr 2 O 3 , and / or Si, Sn, Ge, N, etc. Dopant elements such as Mg can be mentioned.
  • the semiconductor film of the present embodiment contains a void in the film, and the halogen element is contained in the void.
  • the void in the present specification refers to a void having a diameter (void diameter) of 1 to 100 nm. The evaluation method of the void diameter will be described later.
  • the halogen element is preferably one or more elements selected from the group consisting of fluorine, chlorine, bromine and iodine, and more preferably one or more elements selected from the group consisting of chlorine, bromine and iodine. ..
  • the inclusion of a halogen element in the void means that a part or all of the inner wall surface of the void is composed of a compound containing a halogen element (for example, a halide).
  • a halogen element when contained in the void, a part or all of the inner wall surface of the void is formed by a compound such as a halide, the wall strength is improved, and it becomes difficult to become a crack starting point. Therefore, it is considered that the effect of stress relaxation by voids can be fully enjoyed and cracks are less likely to occur.
  • the entire inner wall surface of the void is formed of a compound containing a halogen element, or a compound containing a halogen element is present on a part of the inner wall surface of the void and the compound is present on the inner wall surface. It is preferably distributed substantially evenly.
  • An example of the former is shown in FIG. 1, and an example of the latter is shown in FIG.
  • FIG. 1 is a conceptual diagram schematically showing a part of a cross section of the semiconductor film 10.
  • the void 11 is formed in the semiconductor film 10
  • the entire inner wall 12 of the void 11 is covered with a compound containing a halogen element.
  • the inside 13 of the inner wall 12 of the void 11 is hollow.
  • FIG. 2 is a conceptual diagram schematically showing a part of a cross section of the semiconductor film 14.
  • the void 15 is formed in the semiconductor film 14, and the compound 16 containing a halogen element is substantially evenly distributed on a part of the inner wall surface of the void 15.
  • the inside 17 of the inner wall of the void 15 is hollow. Cracks can be effectively suppressed by setting the states as shown in FIGS. 1 and 2.
  • the void in this embodiment can be observed and evaluated by the following method. That is, when a flaky sample having an arbitrary cross section of a semiconductor film is prepared and observed by STEM or TEM, a low density region is perceived in the film from the contrast difference of the STEM image or TEM image. These low-density regions are synonymous with voids, and those having a value of 1.5 times the longest side length of 1 to 100 nm are called voids, and those having a value of 1.5 times the longest side length are called void diameters.
  • the concentrations of Ga and O which are the main components of the semiconductor film, decrease, and the corresponding amount of other components is not detected, so that a low density region (void) is generated.
  • this method does not physically observe the inner wall surface of the void, the halogen element is detected from the region where the void is located after confirming that the void is present in the STEM image or TEM image. Therefore, it is considered to be synonymous with the presence of a compound containing a halogen element on the inner wall surface of the void. It is possible to show that the halogen element is present in the semiconductor film by using D-SIMS or the like, but since it is not possible to distinguish whether the halogen element is present in the film or in the void, the analysis of this embodiment is performed. The meaning is essentially different from the method.
  • the semiconductor film can contain a Group 14 element as a dopant at a ratio of 1.0 ⁇ 10 16 to 1.0 ⁇ 10 21 / cm 3 .
  • the Group 14 elements are Group 14 elements according to the periodic table formulated by the IUPAC (International Union of Pure and Applied Chemistry). Specifically, carbon (C), silicon (Si), germanium (Ge), and so on. It is either tin (Sn) or lead (Pb).
  • the amount of dopant can be appropriately changed according to the desired characteristics, but is preferably 1.0 ⁇ 10 16 to 1.0 ⁇ 10 21 / cm 3 , and more preferably 1.0 ⁇ 10 17 to 1.0. ⁇ 10 19 / cm 3 . It is preferable that these dopants are uniformly distributed in the film and the dopant concentrations on the front surface and the back surface of the semiconductor film are about the same.
  • the semiconductor film is preferably an alignment film oriented in a specific plane orientation.
  • the orientation of the semiconductor film can be investigated by a known method, but it can be investigated, for example, by performing reverse pole map orientation mapping using an electron backscatter diffraction device (EBSD).
  • EBSD electron backscatter diffraction device
  • the semiconductor film may be c-axis oriented in the film surface normal direction, or may be c-axis oriented in the film surface normal direction and biaxially oriented in the in-plane direction of the film surface. Good.
  • the film thickness of the semiconductor film may be appropriately adjusted from the viewpoint of cost and required characteristics. That is, if it is too thick, it takes time to form a film, so it is preferable that the film is not extremely thick from the viewpoint of cost. Further, when a device that requires a particularly high dielectric strength is manufactured, a thick film is preferable. On the other hand, when manufacturing a device that requires conductivity in the vertical direction (thickness direction), a thin film is preferable. As described above, the film thickness may be appropriately adjusted according to the desired characteristics, but is typically 0.1 to 50 ⁇ m, preferably 0.2 to 20 ⁇ m, and more preferably 0.2 to 10 ⁇ m. By setting the thickness in such a range, it is possible to achieve both cost and semiconductor characteristics. When a self-supporting semiconductor film is required, a thick film may be used, for example, 50 ⁇ m or more, preferably 100 ⁇ m or more, and there is no particular upper limit unless there is a cost limitation.
  • the semiconductor film has an area of preferably 20 cm 2 or more, more preferably 70 cm 2 or more, and further preferably 170 cm 2 or more on one side thereof.
  • the upper limit of the size of the semiconductor film is not particularly limited, but is typically 700 cm 2 or less on one side.
  • the semiconductor film may be in the form of a self-supporting film of the film alone, or may be formed on a support substrate.
  • the support substrate preferably has a corundum structure and is oriented in two axes of the c-axis and the a-axis (biaxially oriented substrate).
  • a biaxially oriented substrate having a corundum structure as the support substrate, it is possible to serve as a seed crystal for heteroepitaxial growth of the semiconductor film.
  • the biaxially oriented substrate may be a polycrystal, a mosaic crystal (a set of crystals whose crystal orientations are slightly deviated), or a single crystal.
  • the main components of the support substrate are ⁇ -Cr 2 O 3 , ⁇ -Fe 2 O 3 , ⁇ -Ti 2 O 3 , ⁇ -V 2 O 3 , ⁇ -Rh 2 O 3 and ⁇ -Al 2 O 3.
  • a material selected from the group or a solid solution containing two or more kinds selected from these groups is preferable, and a material different from ⁇ -Cr 2 O 3 or ⁇ -Cr 2 O 3 ( ⁇ -Cr 2 in the previous group).
  • a solid solution with a material other than O 3 ) is particularly preferable.
  • a composite base substrate on which the configured alignment layer is formed can also be used.
  • the alignment layer is a material selected from the group consisting of ⁇ -Cr 2 O 3 , ⁇ -Fe 2 O 3 , ⁇ -Ti 2 O 3 , ⁇ -V 2 O 3, and ⁇ -Rh 2 O 3 , or ⁇ -.
  • the semiconductor film formed on the film-forming substrate may be separated and reprinted on another support substrate.
  • the material of the other support substrate is not particularly limited, but a suitable material may be selected from the viewpoint of material physical characteristics.
  • a metal substrate such as Cu, a ceramic substrate such as SiC or AlN, or the like is preferable.
  • An example of such a support substrate is a substrate made of a Cu—Mo composite metal. The composite ratio of Cu and Mo can be appropriately selected in consideration of the coefficient of thermal expansion matching with the semiconductor film, the thermal conductivity, the conductivity and the like.
  • a biaxially oriented substrate composed of a solid solution of ⁇ -Cr 2 O 3 or ⁇ -Cr 2 O 3 and a dissimilar material, or ⁇ -Cr 2 O 3 or ⁇ -Cr 2 O 3
  • Any composite substrate having an alignment layer composed of a solid solution of different materials is preferable. By doing so, it is possible to serve as both a seed crystal (base substrate for film formation) for heteroepitaxial growth of the semiconductor film and a support substrate, and it is possible to significantly reduce crystal defects in the semiconductor film.
  • the manufacturing method of the semiconductor film is not particularly limited as long as a void containing a halogen element can be formed in the film.
  • a biaxially oriented substrate composed of a solid solution of ⁇ -Cr 2 O 3 or ⁇ -Cr 2 O 3 and a dissimilar material, or ⁇ -Cr 2 O 3 or ⁇ -Cr 2 O 3 It is preferable to use any of the composite base substrates having an orientation layer composed of a solid solution of different materials as the base substrate for film formation.
  • a method for manufacturing a semiconductor film will be described in the order of (1) manufacturing of a composite substrate and (2) formation of a semiconductor film.
  • a sapphire substrate is prepared, (b) a predetermined orientation precursor layer is prepared, and (c) the orientation precursor layer is heat-treated on the sapphire substrate. It is preferable to convert at least a portion near the sapphire substrate into an alignment layer and, if desired, perform processing such as (d) grinding or polishing to expose the surface of the alignment layer.
  • This alignment precursor layer becomes an alignment layer by heat treatment, and is a material having a corundum-type crystal structure whose a-axis length and / or c-axis length is larger than sapphire, or a-axis length and / or c-axis by heat treatment described later.
  • the orientation precursor layer may contain trace components in addition to the material having a corundum-type crystal structure. According to such a manufacturing method, the growth of the alignment layer can be promoted by using the sapphire substrate as a seed crystal. That is, the high crystallinity and crystal orientation orientation peculiar to a single crystal of a sapphire substrate are inherited by the alignment layer.
  • a sapphire substrate is prepared.
  • the sapphire substrate used may have any orientation plane. That is, it may have a-plane, c-plane, r-plane, and m-plane, and may have a predetermined off-angle with respect to these planes.
  • c-plane sapphire since it is c-axis oriented with respect to the surface, it is possible to easily heteroepitaxially grow an oriented layer oriented c-axis on it.
  • a sapphire substrate to which a dopant has been added in order to adjust the electrical characteristics.
  • dopants can be used as such dopants.
  • orientation precursor layer A material having a corundum-type crystal structure whose a-axis length and / or c-axis length is larger than sapphire, or a corundum-type crystal structure whose a-axis length and / or c-axis length is larger than sapphire by heat treatment.
  • An orientation precursor layer containing the material to be used is prepared.
  • the material of the alignment precursor the material of the above-mentioned alignment layer can be used, or the material of the above-mentioned orientation layer by heat treatment can also be used.
  • the method for forming the orientation precursor layer is not particularly limited, and a known method can be adopted.
  • Examples of methods for forming an orientation precursor layer include AD (aerosol deposition) method, sol-gel method, hydrothermal method, sputtering method, thin-film deposition method, various CVD (chemical vapor deposition) methods, and PLD (pulse laser deposition). Methods such as the method, CVT (chemical vapor deposition) method, and sublimation method can be mentioned.
  • Examples of the CVD method include a thermal CVD method, a plasma CVD method, a mist CVD method, an MO (organic metal) CVD method, and the like.
  • a method may be used in which a molded product of the orientation precursor is prepared in advance and the molded product is placed on a sapphire substrate.
  • Such a molded product can be produced by molding the material of the orientation precursor by a method such as tape molding or press molding. Further, it is also possible to use a method in which a polycrystal prepared in advance by various CVD methods or sintering is used as the orientation precursor layer and placed on a sapphire substrate.
  • a method of directly forming an orientation precursor layer by using an AD method, various CVD methods, or a sputtering method is preferable.
  • the AD method does not require a high vacuum process and has a relatively high film formation rate, and is therefore preferable in terms of manufacturing cost.
  • the sputtering method it is possible to form a film using a target made of the same material as the alignment precursor layer, but it is also possible to use a reactive sputtering method in which a metal target is used to form a film in an oxygen atmosphere. it can.
  • a method of placing the molded product prepared in advance on sapphire is also preferable as a simple method, but since the orientation precursor layer is not dense, a process of densification is required in the heat treatment step described later.
  • the method using a polycrystal prepared in advance as the orientation precursor layer requires two steps, a step of preparing the polycrystal and a step of heat-treating on the sapphire substrate. Further, in order to improve the adhesion between the polycrystal and the sapphire substrate, it is necessary to take measures such as keeping the surface of the polycrystal sufficiently smooth.
  • known conditions can be used for either method, a method of directly forming an orientation precursor layer using the AD method and a method of placing a prefabricated molded product on a sapphire substrate will be described below. ..
  • the AD method is a technology in which fine particles and fine particle raw materials are mixed with gas to form an aerosol, and this aerosol is jetted at high speed from a nozzle to collide with a substrate to form a film, which is said to be able to form a dense film at room temperature. It has characteristics.
  • FIG. 3 shows an example of a film forming apparatus (AD apparatus) used in such an AD method.
  • the film forming apparatus 20 shown in FIG. 3 is configured as an apparatus used in the AD method of injecting raw material powder onto a substrate in an atmosphere of atmospheric pressure lower than atmospheric pressure.
  • the film forming apparatus 20 includes an aerosol generation unit 22 that generates an aerosol of a raw material powder containing a raw material component, and a film forming unit 30 that injects the raw material powder onto a sapphire substrate 21 to form a film containing the raw material component.
  • the aerosol generation unit 22 includes an aerosol generation chamber 23 that houses raw material powder and receives a carrier gas supply from a gas cylinder (not shown) to generate an aerosol, and a raw material supply pipe 24 that supplies the generated aerosol to the film forming unit 30.
  • the aerosol generation chamber 23 and the aerosol in the aerosol are provided with a vibration exciter 25 that vibrates at a frequency of 10 to 100 Hz.
  • the film forming unit 30 has a film forming chamber 32 that injects aerosols onto the sapphire substrate 21, a substrate holder 34 that is arranged inside the film forming chamber 32 and fixes the sapphire substrate 21, and the substrate holder 34 is X-axis-Y-axis. It is equipped with an XY stage 33 that moves in a direction. Further, the film forming section 30 includes an injection nozzle 36 having a slit 37 formed at the tip thereof to inject aerosol into the sapphire substrate 21, and a vacuum pump 38 for reducing the pressure in the film forming chamber 32.
  • the AD method can control the film thickness, film quality, etc. depending on the film forming conditions.
  • the form of the AD film is easily affected by the collision rate of the raw material powder with the substrate, the particle size of the raw material powder, the aggregated state of the raw material powder in the aerosol, the injection amount per unit time, and the like.
  • the collision speed of the raw material powder with the sapphire substrate 21 is affected by the differential pressure between the film forming chamber 32 and the inside of the injection nozzle 36, the opening area of the slit 37 of the injection nozzle 36, and the like. If appropriate conditions are not used, the AD film may become a powder or form unwanted pores, and it is necessary to appropriately control these factors.
  • the raw material powder of the orientation precursor can be molded to prepare the molded product.
  • the orientation precursor layer is a press molded body.
  • the press-molded product can be produced by press-molding the raw material powder of the orientation precursor based on a known method.
  • the raw material powder is placed in a mold, preferably 100 to 400 kgf / cm 2 , more preferably 150. It may be produced by pressing at a pressure of about 300 kgf / cm 2 .
  • the molding method is not particularly limited, and in addition to press molding, tape molding, casting molding, extrusion molding, doctor blade method, and any combination thereof can be used.
  • additives such as a binder, a plasticizer, a dispersant, and a dispersion medium are appropriately added to the raw material powder to form a slurry, and the slurry is passed through a narrow slit-shaped discharge port to form a sheet. It is preferable to discharge and mold.
  • the thickness of the molded product formed into a sheet is not limited, but is preferably 5 to 500 ⁇ m from the viewpoint of handling. Further, when a thick orientation precursor layer is required, a large number of these sheet molded products may be stacked and used as a desired thickness.
  • the portion near the sapphire substrate becomes an orientation layer by the subsequent heat treatment on the sapphire substrate.
  • the molded product may contain trace components such as a sintering aid in addition to the material having or bringing about a corundum-type crystal structure.
  • (C) Heat treatment of the alignment precursor layer on the sapphire substrate The sapphire substrate on which the alignment precursor layer is formed is heat-treated at a temperature of 1000 ° C. or higher. By this heat treatment, at least a portion of the alignment precursor layer near the sapphire substrate can be converted into a dense alignment layer. Further, this heat treatment makes it possible to grow the oriented layer heteroepitaxially. That is, by forming the alignment layer with a material having a corundum-type crystal structure, heteroepitaxial growth occurs in which the material having a corundum-type crystal structure grows as a seed crystal using a sapphire substrate during heat treatment. At that time, the crystals are rearranged, and the crystals are arranged according to the crystal plane of the sapphire substrate.
  • the crystal axes of the sapphire substrate and the alignment layer can be aligned.
  • the sapphire substrate and the alignment layer can both be oriented in the c-axis with respect to the surface of the base substrate.
  • this heat treatment makes it possible to form an inclined composition region in a part of the alignment layer. That is, during the heat treatment, a reaction occurs at the interface between the sapphire substrate and the alignment precursor layer, and the Al component in the sapphire substrate diffuses into the alignment precursor layer and / or the component in the alignment precursor layer is sapphire. By diffusing into the substrate, an inclined composition region composed of a solid solution containing ⁇ -Al 2 O 3 is formed.
  • the orientation precursor layer is in a non-oriented state at the time of its production, that is, it is an amorphous or non-oriented polycrystal, and it is preferable to cause crystal rearrangement using sapphire as a seed crystal during this heat treatment step. By doing so, the crystal defects reaching the surface of the alignment layer can be effectively reduced. The reason for this is not clear, but it is thought that the rearrangement of the crystal structure of the solid-phase orientation precursor layer once formed using sapphire as a seed may be effective in eliminating crystal defects.
  • the heat treatment is not particularly limited as long as a corundum-type crystal structure is obtained and heteroepitaxial growth using a sapphire substrate as a seed occurs, and the heat treatment can be carried out in a known heat treatment furnace such as a tube furnace or a hot plate. Further, in addition to these heat treatments under normal pressure (pressless), pressure heat treatments such as hot press and HIP, and combinations of normal pressure heat treatments and pressure heat treatments can also be used.
  • the heat treatment conditions can be appropriately selected depending on the material used for the alignment layer.
  • the heat treatment atmosphere can be selected from atmospheric, vacuum, nitrogen and inert gas atmospheres.
  • the preferred heat treatment temperature also varies depending on the material used for the alignment layer, but is preferably 1000 to 2000 ° C, more preferably 1200 to 2000 ° C, for example.
  • the heat treatment temperature and holding time are related to the thickness of the alignment layer generated by heteroepitaxial growth and the thickness of the inclined composition region formed by diffusion with the sapphire substrate, and are related to the type of material, the target alignment layer, and the thickness of the inclined composition region. It can be adjusted as appropriate depending on the size. However, when a prefabricated molded product is used as an orientation precursor layer, it is necessary to sinter and densify it during heat treatment, and atmospheric firing at high temperature, hot pressing, HIP, or a combination thereof is preferable. ..
  • the surface pressure is preferably 50 kgf / cm 2 or more, more preferably 100 kgf / cm 2 or more, particularly preferably 200 kgf / cm 2 or more, the upper limit is not particularly limited.
  • the firing temperature is also not particularly limited as long as sintering, densification, and heteroepitaxial growth occur, but is preferably 1000 ° C. or higher, more preferably 1200 ° C. or higher, further preferably 1400 ° C. or higher, and particularly preferably 1600 ° C. or higher.
  • the firing atmosphere can also be selected from atmosphere, vacuum, nitrogen and an inert gas atmosphere.
  • the firing jig such as a mold, those made of graphite or alumina can be used.
  • the surface derived from the alignment precursor layer is subjected to processing such as grinding or polishing to expose the surface of the alignment layer.
  • processing such as grinding or polishing to expose the surface of the alignment layer.
  • the material having excellent orientation is exposed on the surface of the alignment layer, so that the semiconductor film can be effectively epitaxially grown on the material.
  • the method for removing the orientation precursor layer and the surface layer is not particularly limited, and examples thereof include a method for grinding and polishing and a method for ion beam milling. Polishing of the surface of the alignment layer is preferably performed by lapping using abrasive grains or chemical mechanical polishing (CMP).
  • an ⁇ -Ga 2 O 3 system semiconductor film is formed on the alignment layer.
  • Known methods can be used to form the semiconductor film, but various CVD methods, HVPE methods, sublimation methods, MBE methods, PLD methods, sputtering methods and other vapor phase deposition methods, hydrothermal methods, Na flux methods and the like can be used. Any of the liquid phase film forming methods is preferable, and the mist CVD method, the hydrothermal method, or the HVPE method is particularly preferable. The mist CVD method will be described below.
  • the raw material solution is atomized or dropletized to generate mist or droplets, and the mist or droplet is conveyed to a film forming chamber equipped with a substrate using a carrier gas, and the mist or droplet is transferred in the film forming chamber.
  • a film forming chamber equipped with a substrate using a carrier gas
  • the mist or droplet is transferred in the film forming chamber.
  • FIG. 4 shows an example of a mist CVD apparatus.
  • the susceptor 50 is made of quartz, and the surface on which the composite substrate 49 is placed is inclined from the horizontal plane.
  • the raw material solution 44a used in the mist CVD method is not limited as long as it is a solution that can obtain an ⁇ -Ga 2 O 3 system semiconductor film, and is, for example, an organic metal complex of Ga, a halide of Ga, and Examples thereof include those in which one or more of organic metal complexes of Ga and a metal forming a solid solution are dissolved in a solvent.
  • the organometallic complex include an acetylacetonate complex
  • examples of a halide include GaCl 3 and GaBr 3 .
  • a halogen element is contained in the raw material solution.
  • the halide may be dissolved directly in the solvent or hydrogen halide in water.
  • the halide may be dissolved in a solution to which an acid (for example, hydrochloric acid) is added, or metal Ga may be dissolved in a solution of water and a hydrohalic acid.
  • an acid for example, hydrochloric acid
  • metal Ga may be dissolved in a solution of water and a hydrohalic acid.
  • a solution containing these components may be added to the raw material solution.
  • an additive such as hydrohalic acid may be added to the raw material solution. Water, alcohol or the like can be used as the solvent.
  • the obtained raw material solution 44a is atomized to generate mist 44b.
  • a preferred example of the atomization method is a method of vibrating the raw material solution 44a using the ultrasonic vibrator 46.
  • the obtained mist 44b is conveyed to the film forming chamber using a carrier gas.
  • the carrier gas is not particularly limited, but one or more of an inert gas such as oxygen, ozone and nitrogen, and a reducing gas such as hydrogen can be used.
  • the film forming chamber (quartz tube 47) is provided with a composite substrate 49.
  • the mist 44b conveyed to the film forming chamber is thermally decomposed and chemically reacted there to form a film on the composite substrate 49.
  • the reaction temperature varies depending on the type of the raw material solution, but is preferably 300 to 800 ° C, more preferably 350 to 700 ° C.
  • the atmosphere in the film forming chamber is not particularly limited as long as a desired semiconductor film can be obtained, and may be an oxygen gas atmosphere, an inert gas atmosphere, a vacuum or a reducing atmosphere, but an air atmosphere is preferable.
  • a droplet of the raw material solution 44a may be used in place of or in addition to the mist 44b.
  • the semiconductor film is formed in this way, but the mist CVD method is generally known as a method for forming a dense film.
  • voids can be formed in the semiconductor film by controlling the flow rate of the carrier gas, the composition of the raw material solution, the Ga ion concentration, the pH, the film formation temperature, and the like. For example, by increasing the concentration of Ga ions in the raw material solution, Ga aggregates are formed in the semiconductor film and voids are formed. Further, if the film forming speed is too fast, voids are likely to be formed, and voids can be formed in the semiconductor film by increasing the supply amount of the carrier gas. However, since these factors interact with each other, complicated control of these factors is required to form voids in the semiconductor film. Such a void forming method is common to other vapor phase film forming methods such as HVPE and MOCVD, and conditions suitable for each film forming method are required.
  • the semiconductor film produced in this way is less likely to crack during film formation. Further, even when the film is separated from the composite substrate 49 to form a self-standing film, it has a characteristic that cracks are unlikely to occur.
  • the crystal phase of the semiconductor film can be evaluated by a known analytical method such as XRD or EBSD.
  • carrier gas such as N 2 and rare gas
  • halogen gas such as H 2 O, gallium halide, Cl 2 and HCl
  • hydrogen halide gas are the main components of the gas in the void.
  • the gas incorporated in these voids contains a halogen element, that is, when a halogen gas such as gallium halide, Cl 2 or HCl, or a hydrogen halide gas is incorporated, all or part of the inner wall of the void is a halide. It is coated with a compound containing, etc. to increase its strength.
  • the void itself is unlikely to be the starting point of cracks, so that it is considered that the effect of suppressing cracks in the semiconductor film can be obtained.
  • the semiconductor film of the present embodiment has extremely small warpage after being formed on the film-forming substrate or when separated from the film-forming substrate to form an independent film.
  • a biaxially oriented substrate composed of a solid solution of ⁇ -Cr 2 O 3 or ⁇ -Cr 2 O 3 and a dissimilar material, or ⁇ -Cr 2 O 3 or ⁇ -Cr 2 O
  • the amount of warpage can be reduced.
  • the amount of warpage when a 2-inch size semiconductor film is produced can be 30 ⁇ m or less, more preferably 20 ⁇ m or less, and further preferably 10 ⁇ m or less. The reason why such a small amount of warpage can be obtained is not clear, but it is considered that the presence of voids in the semiconductor film relaxes the stress in the semiconductor film during film formation.
  • the semiconductor film of the present embodiment can be a film having a small mosaic property.
  • the ⁇ -Ga 2 O 3 film formed on the conventional sapphire substrate may be an aggregate of domains (mosaic crystals) having slightly different crystal orientations. The cause of this is not clear, but it can be mentioned that the film formation temperature is relatively low because ⁇ -Ga 2 O 3 is a metastable phase. Since the film formation temperature is low, it is difficult for the adsorbed components to migrate on the substrate surface, and step flow growth is difficult. For this reason, the growth mode of island-like growth (three-dimensional growth) tends to be dominant.
  • the semiconductor film of the present embodiment is a single crystal substrate composed of a solid solution of ⁇ -Cr 2 O 3 or ⁇ -Cr 2 O 3 and a dissimilar material, or ⁇ -Cr 2 O 3 as a base substrate for film formation.
  • any of the composite substrates having a single crystal layer composed of a solid solution of ⁇ -Cr 2 O 3 and a dissimilar material is used and the film forming conditions are appropriately controlled, there is no mosaic property (that is, a single crystal).
  • a semiconductor film having a small mosaic property can be obtained. The reason for this is not clear, but in addition to the lattice constants of the semiconductor film being filmed and the underlying substrate for film formation being close or the same, the presence of voids in the semiconductor film causes filming or film formation. It is considered that this is because the stress in the semiconductor film at the time of later temperature decrease is relaxed and the orientation directions are easily aligned.
  • the film formation temperature is, for example, 600 ° C. or higher, preferably 700 ° C. or higher, more preferably 800 ° C.
  • the following method can be used to evaluate the mosaic property of the semiconductor film by X-ray locking curve measurement (XRC).
  • XRC X-ray locking curve measurement
  • -Measuring device Bruker-AXS D8-DISCOVER
  • X-ray source CuK ⁇ ray, tube voltage 40kV, tube current 40mA, Ge (022) asymmetric reflection monochromator for parallel monochromator
  • Collimator diameter 0.5mm ⁇
  • Anti-scattering slit 3mm ⁇ ⁇ step width: 0.005 ° -Counting time: 0.5 seconds-XRD analysis software: Bruker-AXS, "LEPTOS" Ver4.03
  • the half width of the (006) plane of the X-ray locking curve is preferably less than 40 seconds, more preferably less than 30 seconds, and there is no problem even if the value is equivalent to the half width peculiar to the X-ray source used for the measurement.
  • the (104) plane half width of the X-ray locking curve is preferably less than 40 seconds, more preferably less than 30 seconds, and there is no problem even if the value is equivalent to the half width peculiar to the X-ray source used for the measurement.
  • the half-value width of the X-ray locking curve is affected by the crystal defect density and the crystal warpage in addition to the above-mentioned mosaic property.
  • the semiconductor film of the present embodiment has few crystal defects, no mosaic property, and warpage. Since it is small, it is considered that such a value can be realized.
  • the obtained semiconductor film can be formed as it is or divided into semiconductor elements.
  • the semiconductor film may be peeled off from the composite substrate to form a single film.
  • a peeling layer may be provided in advance on the alignment layer surface (deposition surface) of the composite base substrate.
  • Examples of such a release layer include those provided with a C injection layer and an H injection layer on the surface of the composite substrate. Further, C or H may be injected into the film at the initial stage of film formation of the semiconductor film to provide a release layer on the semiconductor film side.
  • a support substrate (mounting substrate) different from the composite substrate is adhered and bonded to the surface of the semiconductor film formed on the composite substrate (that is, the surface opposite to the composite substrate), and then the semiconductor film is formed. It is also possible to peel off the composite substrate from the substrate.
  • a support substrate (mounting substrate) a substrate having a coefficient of thermal expansion at 25 to 400 ° C. of 6 to 13 ppm / K, for example, a substrate composed of a Cu—Mo composite metal can be used.
  • known methods such as brazing, soldering, and solid phase bonding can be mentioned.
  • an electrode such as an ohmic electrode or a Schottky electrode, or another layer such as an adhesive layer may be provided between the semiconductor film and the support substrate.
  • Example 1 (1) Preparation of composite substrate Substrate Cr 2 O 3 powder (Lanxess Colortherm Green) as raw material powder, sapphire (diameter 50.8 mm (2 inches), thickness 0.43 mm, c-plane, off-angle) as substrate Using (0.2 °), an AD film (alignment precursor layer) made of Cr 2 O 3 was formed on a seed substrate (sapphire substrate) by the AD apparatus shown in FIG.
  • the AD film formation conditions were as follows. That is, the carrier gas was N 2, and a ceramic nozzle having a slit having a long side of 5 mm and a short side of 0.3 mm was used.
  • the scanning conditions of the nozzle are 0.5 mm / s, movement of 55 mm perpendicular to the long side of the slit and in the forward direction, movement of 5 mm in the direction of the long side of the slit, and vertical and return to the long side of the slit. Repeated scanning of moving 55 mm in the direction, moving 5 mm in the long side direction of the slit and in the direction opposite to the initial position, and when moving 55 mm from the initial position in the long side direction of the slit, scan in the opposite direction.
  • the cycle of returning to the initial position was set as one cycle, and this was repeated for 500 cycles.
  • the set pressure of the transport gas was adjusted to 0.06 MPa, the flow rate was adjusted to 6 L / min, and the pressure in the chamber was adjusted to 100 Pa or less.
  • the AD film thus formed had a thickness of about 100 ⁇ m.
  • the sapphire substrate on which the AD film was formed was taken out from the AD apparatus and annealed at 1700 ° C. for 4 hours in a nitrogen atmosphere.
  • the substrate thus obtained was fixed to a ceramic surface plate, and the surface on the side where the AD film was formed was ground to # 2000 using a grindstone to flatten the plate surface.
  • the plate surface was smoothed by lapping using diamond abrasive grains. The flatness was improved while the size of the abrasive grains was gradually reduced from 3 ⁇ m to 0.5 ⁇ m.
  • CMP chemical mechanical polishing
  • the arithmetic mean roughness Ra after processing was 0.1 nm, the amount of grinding and polishing was 50 ⁇ m, and the substrate thickness after completion of polishing was 0.48 mm.
  • the surface on the side where the AD film is formed is referred to as a "surface".
  • the Cr oxide layer is a layer having a biaxially oriented corundum-type crystal structure oriented in the c-axis direction in the substrate normal direction and also in the in-plane direction. .. From these, it was shown that an orientation layer made of ⁇ -Cr 2 O 3 was formed on the surface of the substrate. From the above, the manufacturing process of the composite base substrate is schematically shown in FIGS. 5 (a) to 5 (d).
  • the a-axis length of the oriented layer was 4.961 ⁇ .
  • the obtained raw material solution 44a was housed in the mist generation source 44.
  • the composite substrate prepared in (1) of Example 1 was placed on the susceptor 50 as the substrate 49, and the heater 48 was operated to raise the temperature inside the quartz tube 47 to 420 ° C.
  • the flow control valves 43a and 43b are opened to supply the diluted gas and the carrier gas into the quartz tube 47 from the diluted gas source 42a and the carrier gas source 42b, and the atmosphere of the quartz tube 47 is sufficiently filled with the diluted gas and the carrier gas.
  • the flow rate of the diluting gas was adjusted to 1.0 L / min and the flow rate of the carrier gas was adjusted to 1.0 L / min.
  • Nitrogen gas was used as the diluent gas and carrier gas.
  • the ultrasonic transducer 46 is vibrated at 1.6 MHz, and the vibration is propagated to the raw material solution 44a through water 45a to mist the raw material solution 44a to form the mist 44b. Generated.
  • This mist 44b is introduced into the quartz tube 47, which is a film forming chamber, by a diluting gas and a carrier gas, reacts in the quartz tube 47, and a film is formed on the substrate 49 by a CVD reaction on the surface of the substrate 49 for 30 minutes. It was laminated to obtain a crystalline semiconductor film. The obtained semiconductor film had no cracks over the entire sample, and no appearance of partial peeling was observed.
  • the manufacturing process of the semiconductor film is schematically shown in FIGS. 6A to 6B.
  • Void diameters were not homogeneous and voids of various sizes were observed, but typically 30-60 nm. At least 29 voids were confirmed within a region of about 0.36 ⁇ m 2 of the cross-section test piece observed in a field of view of 200,000 times.
  • Example 2 Formation of ⁇ -Ga 2 O 3 layer (semiconductor film) by mist CVD method
  • the gallium chloride solution was used.
  • a semiconductor film was formed in the same manner as in Example 1 except that the gallium bromide solution had a gallium ion concentration of 3 mol / L.
  • the gallium bromide solution was prepared by adding metal Ga to hydrobromic acid and stirring at room temperature for 3 weeks. The obtained semiconductor film had no cracks over the entire sample, and no appearance of partial peeling was observed.
  • Example 3 Formation of ⁇ -Ga 2 O 3 layer (semiconductor film) by mist CVD method
  • the gallium chloride solution was used in the step of preparing the raw material solution 44a at the time of forming the ⁇ -Ga 2 O 3 film (semiconductor film) by mist CVD.
  • a semiconductor film was formed in the same manner as in Example 1 except that the gallium iodide solution had a gallium ion concentration of 3 mol / L.
  • the gallium iodide solution was prepared by adding metal Ga to hydroiodic acid and stirring at room temperature for 3 weeks. The obtained semiconductor film had no cracks over the entire sample, and no appearance of partial peeling was observed.
  • Example 2d Cross section STEM-EDX Using the same test piece as in Example 3 (2c), STEM-EDX analysis was performed under the same conditions as in Example 1 (4d). From the obtained HAADF-STEM image, a plurality of low-contrast regions were observed as in the TEM image, suggesting the presence of voids. From the EDX analysis of the void portion, the intensities of Ga and O tended to decrease, and it was confirmed that voids were present. Further, from the EDX spectrum, I was detected from the void portion, but I was not detected from the region other than the void, indicating that the inner wall of the void was composed of a compound containing I.
  • the obtained raw material solution 44a was housed in the mist generation source 44.
  • the sapphire substrate was placed on the susceptor 50 as the substrate 49, and the heater 48 was operated to raise the temperature inside the quartz tube 47 to 565 ° C.
  • the flow control valves 43a and 43b are opened to supply the diluted gas and the carrier gas into the quartz tube 47 from the diluted gas source 42a and the carrier gas source 42b, and the atmosphere of the quartz tube 47 is sufficiently filled with the diluted gas and the carrier gas.
  • the flow rate of the diluting gas was adjusted to 2.0 L / min and the flow rate of the carrier gas was adjusted to 2.0 L / min.
  • Nitrogen gas was used as the diluent gas and carrier gas.
  • the ultrasonic transducer 46 is vibrated at 4.8 MHz, and the vibration is propagated to the raw material solution 44a through water 45a to mist the raw material solution 44a to form the mist 44b. Generated.
  • This mist 44b is introduced into the quartz tube 47, which is a film forming chamber, by a diluting gas and a carrier gas, reacts in the quartz tube 47, and a film is formed on the substrate 49 by a CVD reaction on the surface of the substrate 49 for 90 minutes. It was laminated to obtain a crystalline semiconductor film. The obtained semiconductor film had cracks, and some peeled parts were observed.
  • the present invention can be used, for example, as a material for power semiconductors.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
PCT/JP2019/025044 2019-06-25 2019-06-25 半導体膜 WO2020261356A1 (ja)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/JP2019/025044 WO2020261356A1 (ja) 2019-06-25 2019-06-25 半導体膜
JP2021528678A JPWO2020261356A1 (enrdf_load_stackoverflow) 2019-06-25 2019-06-25

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2019/025044 WO2020261356A1 (ja) 2019-06-25 2019-06-25 半導体膜

Publications (1)

Publication Number Publication Date
WO2020261356A1 true WO2020261356A1 (ja) 2020-12-30

Family

ID=74060796

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2019/025044 WO2020261356A1 (ja) 2019-06-25 2019-06-25 半導体膜

Country Status (2)

Country Link
JP (1) JPWO2020261356A1 (enrdf_load_stackoverflow)
WO (1) WO2020261356A1 (enrdf_load_stackoverflow)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016100593A (ja) * 2014-11-26 2016-05-30 株式会社Flosfia 結晶性積層構造体
JP2016225472A (ja) * 2015-05-29 2016-12-28 株式会社東芝 半導体装置、及び、半導体装置の製造方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016100593A (ja) * 2014-11-26 2016-05-30 株式会社Flosfia 結晶性積層構造体
JP2016225472A (ja) * 2015-05-29 2016-12-28 株式会社東芝 半導体装置、及び、半導体装置の製造方法

Also Published As

Publication number Publication date
JPWO2020261356A1 (enrdf_load_stackoverflow) 2020-12-30

Similar Documents

Publication Publication Date Title
JP6784871B1 (ja) 半導体膜
US12159907B2 (en) Semiconductor film
US12351941B2 (en) Ground substrate and method for producing same
US20210355602A1 (en) Underlying substrate
US11942520B2 (en) Semiconductor film
JP7176099B2 (ja) 半導体膜
WO2020261574A1 (ja) 半導体膜
JP7320070B2 (ja) 下地基板及びその製造方法
WO2020261356A1 (ja) 半導体膜
WO2021064817A1 (ja) 下地基板及びその製造方法
JP7108783B2 (ja) 半導体膜

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19934768

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2021528678

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19934768

Country of ref document: EP

Kind code of ref document: A1