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  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02107—Forming insulating materials on a substrate
  • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
  • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
  • H01L21/02172—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides
  • H01L21/02175—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides characterised by the metal
• • 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
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/08—Oxides
  • C23C14/086—Oxides of zinc, germanium, cadmium, indium, tin, thallium or bismuth
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  • 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
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/225—Oblique incidence of vaporised material on substrate
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  • 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
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
• • 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
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/50—Substrate holders
• • 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
  • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
  • C30B25/02—Epitaxial-layer growth
  • C30B25/10—Heating of the reaction chamber or the substrate
• • 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
• • 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
  • C30B29/60—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape characterised by shape
  • C30B29/605—Products containing multiple oriented crystallites, e.g. columnar crystallites
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
  • H01J37/3402—Gas-filled discharge tubes operating with cathodic sputtering using supplementary magnetic fields
  • H01J37/3405—Magnetron sputtering
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02107—Forming insulating materials on a substrate
  • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
  • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
  • H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
  • H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
  • H01L21/02274—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition in the presence of a plasma [PECVD]
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
  • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
  • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
  • H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02367—Substrates
  • H01L21/0237—Materials
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  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02518—Deposited layers
  • H01L21/02521—Materials
  • H01L21/02551—Group 12/16 materials
  • H01L21/02554—Oxides
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  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02518—Deposited layers
  • H01L21/02609—Crystal orientation
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  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02612—Formation types
  • H01L21/02617—Deposition types
  • H01L21/02631—Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation

Definitions

• the present invention relates to a method for producing a single crystal or polycrystalline thin film oriented in a predetermined direction.
• the present invention is particularly suitable for the production of zinc oxide (ZnO) thin films.
• Transducers are elements that excite or detect acoustic surface waves and Balta waves. Measuring transducers are mainly used for measuring material constants, exploring defects and scratches in media, and measuring stress. .
• a piezoelectric material having a piezoelectric effect which is a phenomenon in which polarization changes as sound is distorted by a sound wave, is used as a transducer.
• the spatial resolution of the measurement system is inversely proportional to the sound speed and proportional to the operating frequency, the above measurement can be performed with a high resolution (by using a transverse wave whose sound speed is slower than the 0 longitudinal wave, excitation and detection in the GO high frequency range) Therefore, there is a need for high-frequency shear wave transducers in the measurement field.
• SAW Surface Acoustic Wave
• SAW devices Conventionally, SAW devices have used Rayleigh waves, which are a combination of longitudinal and transverse waves, propagating on a piezoelectric film. Since Rayleigh waves are attenuated when they are reflected by the end face of the piezoelectric film, it has been necessary to provide a reflector in the past to prevent this attenuation.
• SAW devices surface SH wave devices
• surface SH wave devices that use surface SH waves that have only a transverse wave component that vibrates parallel to the piezoelectric film have come to be used. Since the surface SH wave is totally reflected at the end face of the piezoelectric film, the surface SH wave device can be made smaller than before without the need for a reflector as in the prior art.
• the above-described transducer surface SH wave device operates in a high frequency region of several hundred MHz to several GHz.
• V v / (2d) between the frequency V (sec—, the speed of sound v (m / s), and the thickness d (m) of the piezoelectric body.
• Velocity of shear wave propagating through If the device is 3000 m / s to 8000 m / s, the thickness d needs to be several / zm to several tens / zm in order for these devices to operate in such a high frequency region.
• Piezoelectric materials that can be thinned to such a thickness include ZnO, Pb (Zr, Ti) 0 (abbreviation: PZT), polyvinylidene fluoride trifluoride.
• polyethylene p (VDF-TrFE)
• VDF-TrFE polyethylene
• the piezoelectric body In order to excite a transverse wave, the piezoelectric body must vibrate in a sliding mode. For this purpose, the polarization axis must be aligned perpendicular to the electric field direction. For this reason, PZT and P (VDF-TrFE) thin films must be polarized by applying a strong electric field (50 MV / m or more) in the in-plane direction. It is difficult to do across areas. On the other hand, the Z ⁇ thin film can excite a transverse wave by aligning its crystal orientation without performing polarization treatment.
• the transverse wave is excited by sandwiching the thin film between the electrodes and making the c-axis and the electric field direction perpendicular. Therefore, it is desirable to use a ZnO thin film in which the c-axis is oriented in one direction in the plane (hereinafter referred to as “c-axis in-plane oriented ZnO thin film”) as the piezoelectric film used in the above-described transducer surface SH wave device. ,.
• the c-axis can be oriented in one direction in the plane.
• the ZnO thin film must be bonded to the electrode formed on the surface of the medium through which the transverse wave propagates through an adhesive layer. Due to the presence of this adhesive layer, the efficiency of converting the vibration of the ZnO thin film into a transverse wave propagating through the medium was reduced.
• the sapphire single crystal substrate is expensive and disadvantageous in terms of cost.
• the type of the substrate is restricted, its characteristics are restricted when applied to a device.
• Patent Document 1 describes that by forming a ZnO thin film doped with aluminum or aluminum oxide on an aluminum electrode layer, the c-axis is oriented in the plane.
• the ZnO thin film contains aluminum or aluminum oxide as an impurity.
• Patent Document 2 a low-resistance ZnO thin film that serves as an electrode is first epitaxially grown on a sapphire (01-12) single crystal substrate, and then a high-resistance ZnO thin film that serves as a piezoelectric material is grown thereon. Is described.
• a c-axis in-plane oriented ZnO thin film can be obtained by depositing a thin film material on a substrate having a temperature gradient (Patent Document 3). According to this method, a c-axis-oriented ZnO thin film can be formed directly on a metal substrate (electrode) without doping impurities. Therefore, the c-axis in-plane oriented ZnO thin film obtained by this method can be suitably used for devices such as transducer surface SH wave devices.
• a c-axis in-plane oriented ZnO thin film can be produced on various substrates such as a glass substrate and a ceramic substrate as well as a metal substrate. Furthermore, this method is not limited to the c-axis in-plane oriented ZnO thin film, but can be applied to the production of a thin film in which a predetermined crystal axis is aligned in a predetermined direction.
• a magnetron sputtering apparatus is used to deposit a thin film material (ZnO) on a substrate.
• Fig. 1 shows an example of a thin film production system using a magnetron sputtering system.
• a magnetron circuit 12 and a cathode 13 are provided in the lower part of the film forming chamber 11, and an anode 14 is provided in the upper part.
• the substrate 10 is disposed on a substrate table 15 immediately below the anode 14 so as to be substantially parallel to the cathode 13 and the anode 14.
• a temperature gradient is formed on the substrate 10 in a direction parallel to the heater 16 and the water cooling device 17 provided on the substrate table 15.
• a temperature gradient naturally formed in the film forming chamber 11 is applied to the substrate 10. Furthermore, a temperature gradient is given.
• a target 18, which is a thin film material, is placed on the upper surface of the cathode 13.
• the magnetron circuit 12 is installed below the cathode 13. Further, a gas source 19 of argon (Ar) gas and oxygen (0) gas is connected to the film forming chamber 11.
• the sputtered raw material forms a uniaxial flow (raw material flow) directed toward the anode 14 in the plasma.
• This raw material flow Reaches the surface of the substrate 10 and the sputtered raw material is deposited on the surface.
• the c-axis of ZnO is oriented in a direction parallel to the substrate due to the temperature gradient.
• Patent Document 1 Japanese Patent Publication No. 50-23918 (first page, left column, line 36 to second page, left column, second line)
• Patent Document 2 Japanese Patent Laid-Open No. 8-228398 ([0017] to [0025])
• Patent Document 3 Japanese Patent No. 3561745 ([0020] to [0031], FIG. 3)
• the problem to be solved by the present invention is to provide a method capable of producing a ZnO thin film having a larger area than that of the prior art, a c-axis in-plane oriented ZnO thin film, and other thin films in which predetermined crystal axes are oriented in a predetermined direction. That is.
• a thin film manufacturing method according to the present invention made to solve the above-mentioned problems is a uniaxial flow of a thin film material formed in plasma, and has a density gradient in a direction perpendicular to the axis.
• a raw material flow is formed, and the substrate is disposed in an inclined manner in the raw material flow so that the substrate is on the upstream side of the raw material flow on the high density side and on the downstream side on the low density side.
• the method for producing a thin film according to the present invention can be suitably used for the production of a zinc oxide thin film.
• the zinc oxide thin film manufacturing method according to the present invention is a uniaxial flow of a thin film material made of zinc oxide and formed in plasma, and has a density gradient in a direction perpendicular to the axis.
• a raw material flow is formed, and the substrate is disposed in an inclined manner in the raw material flow so that the substrate is on the upstream side of the raw material flow on the high density side and on the downstream side on the low density side.
• the “raw material flow” refers to a uniaxial flow of a thin film raw material formed in plasma.
• FIG. 1 is a cross-sectional view of a conventional thin film manufacturing apparatus.
• FIG. 2 is a cross-sectional view of a thin film manufacturing apparatus for carrying out the thin film manufacturing method according to the present invention.
• FIG. 3 (a) A diagram showing the arrangement of the substrates and the angle of incidence of the raw material flow on the substrates in this example and (b) comparative example.
• FIG. 4 is a chart of 20 / ⁇ scanning X-ray diffraction measurement of this example.
• FIG. 5 is a diagram for explaining (a) 2 ⁇ I ⁇ -scanning X-ray diffraction measurement and (b) ⁇ -scanning X-ray diffraction measurement.
• FIG. 6 is a graph showing the full width at half maximum of the peak obtained by ⁇ -scanning X-ray diffraction in this example and the comparative example.
• FIG. 7 Cross-sectional view showing another example of a thin film manufacturing apparatus for carrying out the method for manufacturing a thin film of the present invention.
• a uniaxial flow (raw material flow) of a thin film raw material that remains in a plasma state or an electrically neutral state is formed in plasma, and the plasma is formed in the plasma.
• the raw material has a density gradient in a direction perpendicular to the axis of the lever.
• Such a raw material stream can be formed by a sputtering apparatus, for example, the magnetron sputtering apparatus. That is, when a raw material stream is formed by these apparatuses, in many cases, a density distribution exists in the raw material stream. By using the temperature gradient generated by this density distribution, the method according to the present invention can be carried out.
• the substrate is disposed in the plasma so as to be inclined with respect to the raw material flow. At that time, the substrate is arranged so that the direction of inclination of the substrate is upstream of the raw material flow on the high density side and downstream of the raw material flow on the low density side.
• the substrate By arranging the substrate in this manner, the substrate naturally forms a temperature gradient such that the temperature is low on the low density side (downstream side) where the temperature is high on the high density side (upstream side). It is done. Thereby, as described above, a thin film having a predetermined crystal axis oriented in the direction of the temperature gradient is formed (deposited) on the substrate.
• the present invention by arranging the substrate in such an inclined manner, the crystal axes are more easily oriented than in the case where the substrate is arranged perpendicular to the raw material flow. As a result, in the thin film formed on the substrate, the area where the predetermined crystal axes are aligned in a predetermined direction is increased. In addition, the production efficiency of the thin film is improved by obtaining a thin film having a large area that is aligned and aligned in this way.
• homogeneous orientation refers to the fact that the variation in the orientation direction of crystal axes is below a predetermined standard.
• One of the criteria is the profile obtained when the angle ⁇ between the incident light and the thin film is changed while the angle ⁇ between the incident light and the reflected light is fixed in the X-ray diffraction measurement of the obtained thin film.
• the crystal axis is assumed to be in a homogeneous orientation.
• the raw material flow When the raw material flow is formed using a normal magnetron sputtering apparatus or the like, as described above, in many cases, the raw material flow has a high density at the center and a low density toward the periphery. Become.
• the direction of the raw material flow is such that the component incident in the direction perpendicular to the anode is large at the center of the anode, and the component in the direction parallel to the anode increases toward the peripheral part away from the center of the anode. It is considered that this component contributes to the homogeneous alignment.
• the incident angle of the raw material flow is smaller when the substrate is placed at the peripheral portion than at the central portion. That is, the component in the direction parallel to the substrate of the raw material flow can be increased over the entire substrate surface.
• a temperature gradient is naturally formed on the substrate as described above.
• a separate heating means and Z or cooling means are provided (for example, a part of the substrate is heated with a heater or the like).
• a larger temperature gradient may be applied by cooling with cooling water or the like.
• the method for producing a thin film of the present invention can be suitably used for producing a c-axis in-plane oriented ZnO thin film.
• the manufacturing method is only to use ZnO as a thin film raw material, and the other processes can be as described above.
• a ZnO thin film with the c-axis oriented in the plane can be obtained.
• the c-axis in-plane oriented ZnO thin film thus obtained can be suitably used for transducer-type surface acoustic wave devices and the like. Since a large-area homogeneously aligned thin film is obtained as described above, the production efficiency of the c-axis in-plane oriented ZnO thin film and devices using the same is improved.
• various substrates such as a ceramic substrate, a glass substrate, other amorphous substrates, and a metal substrate such as a copper substrate and an aluminum substrate can be used.
• a composite substrate such as a metal film deposition substrate in which a metal film is deposited on the surface of a ceramic substrate or a glass plate can also be used.
• the c-axis in-plane oriented ZnO thin film formed on a metal substrate or a metal film deposition substrate can be suitably used for a transducer or a surface acoustic wave device using these substrates as electrodes.
• a c-axis in-plane oriented Z ⁇ thin film on a single crystal substrate such as sapphire, a high-quality single crystal thin film with high crystallinity can be obtained.
• FIG. 2 is a cross-sectional view of a thin film manufacturing apparatus for carrying out the ZnO thin film manufacturing method of the present invention.
• This equipment is magnetron sputtering, similar to the conventional thin film production equipment (Fig. 1).
• the plasma is generated by this, and the target which is the raw material of the thin film is sputtered and deposited on the substrate.
• the film formation chamber 21, the magnetron circuit 22, the cathode 23, the anode 24, the target 28, and the gas source 29 are the same as those in FIG.
• a ZnO sintered body is used for the target 28.
• the surface of the substrate base 25 is positioned away from the line connecting the centers of the magnetron circuit 22, the cathode 23, and the anode 24 (dashed line in the figure). Tilted and fixed. Since the substrate 20 is installed on the surface of the substrate table 25, the substrate 20 is also inclined with respect to the center line. This inclination is such that the distance from the cathode 23 is closer at the end 20a closer to the center line of the substrate 20 than at the end 20b farther from the center line force.
• the thin film manufacturing apparatus of the present embodiment is not provided with a heater or a water cooling apparatus for applying a temperature gradient to the substrate.
• the point that plasma is generated in the vicinity of 8 and the target 28 is sputtered is the same as the conventional thin film manufacturing apparatus (FIG. 1).
• the sputtered ZnO forms a uniaxial flow (raw material flow) in the uniaxial direction toward the anode 24 together with the oxygen plasma by the voltage between the cathode 23 and the anode 24.
• the density of the raw material flow decreases with increasing distance from the center of the anode 24 and does not exist beyond a certain distance from the center. That is, the raw material flow exists only in the columnar region 30 having the center line as the central axis. At a position sufficiently away from the target 28 toward the anode 24, the density of the raw material flow becomes lower as the center line force that is the highest in the central axis is separated.
• the raw material stream reaches the surface of the substrate 20, and ZnO is deposited on the surface.
• the substrate 20 is fixed at a position where the center line force is also deviated, a temperature gradient is formed on the substrate 20 such that the temperature of the end 20b is lower than that of the end 20a.
• the c-axis of ZnO is oriented in the direction parallel to the substrate.
• ⁇ a is smaller than the incident angle 0 b of the raw material flow 32 to the substrate 31b in the apparatus of FIG. 1 (FIG. 3 (b)).
• this example is formed on the substrate rather than using the apparatus of FIG. In the ZnO thin film, the area where the c-axes are aligned and aligned increases.
• the substrate 31a and the center line 34 do not intersect, but even when the substrate 3 lc is disposed at a position including the center line 34 as shown in FIG.
• the region 35 in the substrate 31c that is distant from the upstream side of the raw material stream 32 as it deviates from the line 34 satisfies the conditions for the substrate placement of the present invention.
• the mean free path becomes short, and highly reactive particles cannot reach the substrate sufficiently. Therefore, for example, when the distance between the substrate and the target is 60 mm, it is desirable that the pressure of the gas introduced into the film formation chamber 21 is 6 ⁇ 10 ⁇ 3 Torr or less.
• the sample was prepared and evaluated.
• the apparatus shown in FIG. 2 was used for sample preparation.
• the radius of the magnetron circuit 22 of the apparatus is 35 mm
• the radius of the cathode 23 and the anode 24 is 51 mm
• the distance between the target 28 and the anode 24 is 60 mm.
• the substrate used was a metal film deposition substrate obtained by depositing aluminum on a Pyrex (registered trademark) glass substrate.
• the substrate has a length of 50 mm, a width of 25 mm, and a thickness of 1 mm, and one end 20a in the length direction is located on the center line at a position on the cathode 23 side by 25 mm from the anode 24.
• a temperature gradient was formed in the length direction of the substrate.
• the power supplied to the cathode 23 was 60 W, and sputtering was performed for 20 hours.
• both the thin film of this example and the comparative example show that the (11-20) plane of ZnO is formed in the direction parallel to the substrate, that is, the c-axis is In-plane orientation indicates that
• the incident light 42 of the X-ray to the surface of the thin film 41 is connected to the incident point X-ray detector 43 of the incident light.
• Angle formed by line 44 The angle 2 ⁇ and the angle ⁇ formed by the incident light 42 and the surface of the thin film 41 are scanned together.
• ⁇ -scanning X-ray diffraction measurement was performed on the thin films of this example and the comparative example.
• ⁇ -running X-ray diffraction measurement scans only ⁇ with 2 ⁇ fixed. The larger the variation of the crystal axes in the oriented sample, the wider the width of the peak appearing on the chart.
• 2 ⁇ was fixed to the 2 ⁇ value of the (11-20) peak obtained by the above 20 / ⁇ -scanning X-ray diffraction measurement, and the ⁇ -scanning X-ray diffraction measurement was performed. The full width at half maximum was calculated for.
• Figure 6 shows the values. The horizontal axis represents the distance from the upstream end of the substrate. From FIG.
• the full width at half maximum is suppressed to 5.5 ° or less over a range of 5 to 35 mm from the upstream end. If the full width at half maximum is 5.5 ° or less, it can be said that the c- axis is sufficiently oriented for use in a device such as a transducer. This range is larger than the range where the full width at half maximum is 5.5 ° or less (distance force S15 of upstream end force 5 to 30 mm) in the comparative example. Therefore, according to the method of this example, it is possible to obtain a c-axis in-plane oriented ZnO thin film having a larger area than that of the comparative example and usable for a device such as a transducer.
• FIG. 7 shows another example of a thin film manufacturing apparatus for carrying out the method for manufacturing a ZnO thin film of the present invention.
• the substrate 20 is fixed at an angle with respect to this line at a position off the line connecting the centers of the magnetron circuit 22, the cathode 23, and the anode 24 (dashed line in the figure).
• the configuration of the film forming chamber 21, the magnetron circuit 22, the cathode 23, the anode 24, the target 28 and the gas source 29 is the same as that of the apparatus of FIG.
• a heater 26 is provided on the substrate end 20a side of the substrate stand 25, and a water cooling device 27 is provided on the substrate end 20b side.
• this thin film manufacturing apparatus is the same as that of the apparatus of FIG. 2 except that a temperature gradient is applied to the substrate 20 by the heater 26 and the cooling device 27.
• the heater 26 and the water cooling device 27 further increase the temperature gradient.
• This configuration is particularly effective when the c-axis of the ZnO thin film is not sufficiently in-plane oriented by the naturally formed temperature gradient alone.

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