JP2006206422A - Apparatus for manufacturing quartz crystal thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical apparatus for manufacturing a quartz crystal thin film, which can be advantageously used for efficiently manufacturing the quartz crystal thin film, especially the quartz crystal thin film in which an AT-cut surface is preferentially oriented and in which the exchange frequency of a reaction vessel is low. <P>SOLUTION: The apparatus for manufacturing the quartz crystal thin film has a reaction vessel made of quartz glass and having an exhaust port; a tubular shielding body attachably and detachably fitted to the reaction vessel; a substrate holder provided at the inner side of the tubular shielding body; a first gas feeding tube for feeding a gas containing a silicon alkoxide being a raw material from the outside to the inside of the reaction vessel, which is arranged in such a manner that the tip end opening part of the tube is directed to the surface of a substrate held by the substrate holder or the peripheral area of the substrate on a planar surface including the substrate surface through respective intervals; and a second gas feeding tube for feeding an oxygen-containing gas. The inside surface of the tubular shielding body is formed of a material inactive to silicon oxides in a gaseous state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for producing a quartz thin film under atmospheric pressure.

  Quartz crystal thin films are used for oscillators, vibrators, surface acoustic wave elements for high-frequency filters, and the like. As a method for producing a quartz crystal thin film, a method of polishing a quartz single crystal obtained by a hydrothermal synthesis method to make a thin film is conventionally known. Further, as a method for directly producing a quartz crystal thin film, a sol-gel method, a plasma chemical vapor deposition (CVD) method, a sputtering method, a laser ablation method and the like are known. However, these production methods have problems such as low yield of crystal crystal thin films that are practically satisfactory, or the necessity of managing large-scale equipment and strict production conditions. It is not necessarily advantageous as a manufacturing method.

  Patent Document 1 describes an atmospheric pressure vapor phase epitaxial growth method as a method for producing a quartz crystal thin film that can be advantageously used industrially. In this atmospheric pressure vapor phase epitaxial growth method, silicon alkoxide and oxygen introduced into a quartz reaction vessel under atmospheric pressure without using a vacuum apparatus, preferably in the presence of a reaction accelerator such as hydrogen chloride. In this method, a quartz crystal thin film is epitaxially grown on a substrate by reaction. In this document, when a quartz crystal thin film is formed on a substrate by atmospheric pressure vapor phase epitaxy, a buffer layer (eg, a quartz thin film, a gallium nitride thin film, etc.) is provided on the substrate in advance. There is a description that the crystallinity of the deposited quartz crystal thin film is improved.

In Non-Patent Document 1, a quartz crystal thin film with an AT cut surface preferentially oriented has an excellent advantage that the temperature dependence of the vibration frequency is low when this is used as a vibrator. A method for manufacturing a quartz crystal thin film by atmospheric pressure vapor phase epitaxy is disclosed. More specifically, when a two-layer quartz thin film is provided as a buffer layer on a substrate in advance, the quartz thin film deposited thereon can be preferentially oriented to the AT cut surface.
JP 2002-80296 A Naoyuki Takahashi and five others, “Rapid Growth of Thick Quartz Films by Catalyst-Enhanced Vapor-Phase Epitaxy under Atmospheric Pressure”, Electrochemical and Solid-State Letters, 6 (5) C77-C78 (2003)

  A quartz crystal thin film having excellent crystallinity can be obtained by the atmospheric pressure vapor phase epitaxial growth method. Usually, in such an atmospheric pressure vapor phase epitaxial growth method, a raw material silicon alkoxide and oxygen are reacted inside a reaction vessel made of quartz glass. However, when a quartz crystal thin film is formed on the substrate by this method, the quartz produced by the reaction between the silicon alkoxide and oxygen tends to adhere to the inner surface of the reaction vessel made of quartz glass. When the crystal is attached to the inner surface of the reaction vessel, the amount of the crystal crystal thin film obtained on the substrate is smaller than the supply amount of the silicon alkoxide and oxygen as raw materials. That is, it becomes difficult to produce a quartz crystal thin film on a substrate with a certain degree of efficiency.

  In addition, when quartz adheres to the inner surface of the reaction vessel made of quartz glass, as the production of the quartz crystal thin film on the substrate is repeated, the vitreous quartz that is the material of the reaction vessel and the quartz adhered to the inner surface of the reaction vessel. Reacts with each other, causing crystals to be precipitated in quartz glass, resulting in a decrease in transparency (referred to as devitrification), and the mechanical strength of the reaction vessel gradually decreases. Breaks. Since the quartz thin film is firmly attached to the inner surface of the reaction vessel, it is difficult to remove it, and the conventional quartz thin film production equipment needs to be replaced frequently, for example, by managing the usage time of the reaction vessel. Therefore, it is not necessarily a practical device.

  An object of the present invention is to provide a practical crystal thin film that can be advantageously used for efficiently producing a quartz crystal thin film, particularly a quartz crystal thin film having an AT-cut surface preferentially oriented, and in which the frequency of replacement of reaction vessels is low. It is to provide a manufacturing apparatus.

  The present invention relates to a reaction vessel made of quartz glass having an exhaust port, a cylindrical shield detachably mounted in the reaction vessel, a substrate holder provided inside the cylindrical shield, and a substrate holder. A gas containing silicon alkoxide as a raw material is supplied from the outside to the inside of the reaction vessel, which is arranged with the tip opening being directed to the surface of the substrate or a region around the substrate on the plane including the substrate surface with a space therebetween. A first gas supply pipe and a second gas supply pipe for supplying an oxygen-containing gas, wherein the inner surface of the cylindrical shield is made of a material that is inert to silicon oxide in a gas phase state. The crystal thin film manufacturing apparatus is characterized by being formed.

Preferred embodiments of the crystal thin film manufacturing apparatus of the present invention are as follows.
(1) The material inert to the silicon oxide in the vapor phase is aluminum oxide, silicon carbide, or trisilicon tetranitride.
(2) The reaction vessel is further provided with a third gas supply pipe for supplying a gas containing a reaction accelerator from the outside to the inside.
(3) The reaction accelerator is hydrogen chloride or ammonia.
(4) The reaction container has all the gas supply pipes at one end, a cylindrical container having an opening at the other end, an exhaust port, and is attached to and detached from the opening of the cylindrical container. The lid portion is detachably mounted, and the cylindrical shield is mounted on the cylindrical container.
(5) The tip opening of the second gas supply pipe is disposed inside the cylindrical shield.
(6) The distance between the tip opening of the second gas supply pipe and the substrate is shorter than the distance between the tip opening of the first gas supply pipe and the substrate.

(7) The second gas supply pipe includes a supply pipe main body and a tip opening unit that is detachably attached to the tip of the supply pipe main body.
(8) The tip opening unit of the second gas supply pipe is bent.
(9) The first gas supply pipe includes a supply pipe main body and a tip opening unit that is detachably attached to the tip of the supply pipe main body.

(10) The cylindrical container is disposed in the horizontal direction, and the substrate holder is disposed so as to support the substrate in an oblique direction with respect to the wall surface of the cylindrical shield.
(11) A heating tool is disposed outside the reaction vessel.
(12) The heating tool is divided into a plurality of heating units along the direction from the first gas supply pipe of the reaction vessel toward the substrate holder, and the heating conditions of each heating unit are controlled independently of each other.
(13) A tip opening of the first gas supply pipe, a tip opening of the second gas supply pipe, and the substrate holder are arranged inside the reaction container with a space between each other, and each of the permeates through which the gas flows. A pair of partition walls with holes are provided.

  The quartz crystal thin film manufacturing apparatus of the present invention includes a cylindrical shielding body formed of a material (eg, aluminum oxide) whose inner surface is inactive with respect to silicon oxide in a gas phase state inside the reaction vessel, Since the quartz produced by the reaction of the raw material gas hardly adheres to the inner surface of the cylindrical shield, the quartz thin film can be efficiently formed on the substrate provided inside the cylindrical shield. Furthermore, the cylindrical shield suppresses the attachment of crystal to the inner surface of the reaction vessel made of quartz glass. For this reason, the quartz crystal thin film manufacturing apparatus of the present invention is practical in that the reaction vessel is hardly devitrified even if the quartz crystal thin film is repeatedly produced, and the reaction vessel is not frequently replaced.

  Moreover, the quartz crystal thin film manufacturing apparatus of the present invention can adjust the supply amount of silicon alkoxide and oxygen to the inside of the reaction vessel, the contact position of silicon alkoxide and oxygen inside the reaction vessel (that is, depending on the reaction of these raw material gases). The crystallinity of the obtained crystal thin film can be easily adjusted by adjusting the crystal generation position) or by adjusting the temperature inside the reaction vessel with a heating tool arranged outside the reaction vessel. Thus, by adjusting the crystallinity of the quartz thin film, for example, when a buffer layer made of an amorphous quartz thin film is formed on the substrate in accordance with the description in Patent Document 1, the crystallinity is excellent on the buffer layer. A quartz crystal thin film can be formed, and two layers of buffer layers (specifically, crystallinity of the quartz thin film used as the upper buffer layer) are formed on the substrate in accordance with the contents described in Non-Patent Document 1 above. The crystallinity of each buffer layer is adjusted to be higher than the crystallinity of the crystal thin film used as the lower buffer layer), the AT cut surface is preferentially formed on these buffer layers. An oriented quartz crystal thin film can be formed. As described above, the crystal thin film manufacturing apparatus of the present invention can be advantageously used for manufacturing a crystal crystal thin film, particularly a crystal crystal thin film preferentially oriented on an AT cut surface.

  The crystal thin film manufacturing apparatus of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration example of a crystal thin film manufacturing apparatus according to the present invention and a method of supplying a raw material gas to the manufacturing apparatus. 2 is a cross-sectional view of the quartz crystal thin film manufacturing apparatus 10 shown in FIG.

  A quartz crystal thin film manufacturing apparatus 10 shown in FIGS. 1 and 2 includes a reaction vessel 12 made of quartz glass having an exhaust port 11, a cylindrical shield 15 detachably mounted in the reaction vessel, and a cylindrical shield 15. A silicon alkoxide as a raw material is introduced from the outside to the inside of the reaction vessel, which is disposed on the surface of the substrate holder 13 provided on the inner side and the substrate 14 supported by the substrate holder 13 with the tip opening being directed to each other with a space therebetween. A first gas supply pipe 21 that supplies a gas to be contained, a second gas supply pipe 22 that supplies an oxygen-containing gas, and the like are included. The cylindrical shield 15 of the quartz crystal thin film device 10 shown in FIGS. 1 and 2 is formed by sintering a material that is inert with respect to silicon oxide in a vapor state, for example, aluminum oxide powder, Its inner surface is formed from aluminum oxide.

  Each of the first gas supply pipe 21 and the second gas supply pipe 22 has a tip opening (substrate) in a region around the substrate 14 on a plane including the surface of the substrate 14 supported by the substrate holder 13. 14 (from the surface side of 14). In this specification, the “region around the substrate on the plane including the substrate surface” refers to the diameter of the substrate from the edge of the substrate surface on the plane including the substrate surface (if the substrate is not circular, It means an area within a distance within a half of the diameter of a circle circumscribing the substrate.

  The crystal thin film manufacturing apparatus 10 includes vaporized silicon alkoxide (vapor of silicon alkoxide) supplied to the inside of the reaction vessel 12 through the first gas supply pipe 21 and the reaction vessel 12 through the second gas supply pipe 22. This is an apparatus for forming a crystal thin film by contacting oxygen supplied to the inside of the substrate under atmospheric pressure and depositing crystal generated by oxidation of silicon alkoxide on the substrate 14. As the silicon alkoxide, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, or a mixture of any combination thereof is used. The oxygen may be an oxygen supply source such as ozone, dinitrogen monoxide, or water. In this specification, atmospheric pressure means not only atmospheric pressure, but also pressure close to atmospheric pressure (within twice the atmospheric pressure and a pressure of 1/2 or more).

  Each of silicon alkoxide and oxygen, which are raw materials for the crystal thin film, is supplied into the reaction vessel 12 as follows, for example.

  Silicon alkoxide, for example, tetraethoxysilane (denoted as “TEOS” in FIG. 1) is liquid at room temperature and is placed inside the vaporizer 19. The tetraethoxysilane put in the vaporizer 19 is heated and vaporized by operating the heater 36, and is supplied to the inside of the reaction vessel 12 through the first gas supply pipe 21. As the heater 36, for example, a high frequency induction heater or a resistance heater is used. In order to keep the tetraethoxysilane contained in the vaporizer 19 at a constant temperature (for example, 70 ° C.), the heater 36 is provided with a control device 46.

In order to supply tetraethoxysilane to the inside of the reaction vessel 12 at an efficient and accurate flow rate, the tetraethoxysilane is usually supplied to the inside of the reaction vessel together with a carrier gas. Examples of carrier gases include nitrogen, argon, and helium. In the reaction vessel 12 of the crystal thin film manufacturing apparatus 10 shown in FIGS. 1 and 2, vaporized tetraethoxysilane (TEOS) together with nitrogen (N ₂ ) as a carrier gas through a first gas supply pipe 21. Supplied. Nitrogen as a carrier gas is supplied from the gas cylinder 51c to the vaporizer 19 through the manual valve 52c, the air-operated valve 54c, and the mass flow controller 55c, and the first gas supply pipe together with tetraethoxysilane vaporized in the vaporizer. 21 and supplied to the inside of the reaction vessel 12. The flow rate of nitrogen supplied to the vaporizer 19 is controlled by the mass flow controller 55c. Further, the supply of nitrogen used as a carrier gas to the vaporizer 19 can be started or stopped by opening and closing the air operated valve 54c. The pressure sensor 53c is used for checking the remaining amount of nitrogen put in the gas cylinder 51c.

Oxygen (O ₂ ) is supplied from the gas cylinder 51 b to the inside of the reaction vessel 12 through the manual valve 52 b, the air operated valve 54 b, the mass flow controller 55 b, and the second gas supply pipe 22. The flow rate of oxygen is controlled by the mass flow controller 55b. Further, the supply of oxygen to the reaction vessel 12 can be started or stopped by opening / closing the air operated valve 54b. The pressure sensor 53b is used to check the remaining amount of oxygen in the gas cylinder 51b.

  In general, oxygen is supplied into the reaction vessel 12 together with nitrogen used as a carrier gas, as in the case of supplying the tetraethoxysilane. Nitrogen used as a carrier gas is mixed with oxygen after passing from a gas cylinder 51c through a manual valve 52c, an air-operated valve 54d, and a mass flow controller 55e, and together with oxygen through the second gas supply pipe 22, the reaction vessel 12 is mixed. Supplied inside. The flow rate of nitrogen used as the oxygen carrier gas is controlled by the mass flow controller 55e. The supply of nitrogen used as an oxygen carrier gas can be started or stopped by opening / closing the air operated valve 54d.

  In this way, the tetraethoxysilane and oxygen supplied to the inside of the reaction vessel 12 are brought into contact with each other to react with each other, thereby generating crystal. As described above, when a crystal crystal thin film is manufactured on a substrate using a conventional crystal thin film manufacturing apparatus, the crystal tends to adhere to the inner surface of the reaction vessel in the form of a thin film. When the crystal thin film adheres to the inner surface of the reaction vessel, the amount of the crystal crystal thin film obtained on the substrate is smaller than the supply amount of the raw material silicon alkoxide and oxygen. That is, it becomes difficult to form a quartz crystal thin film on a substrate with a certain degree of efficiency.

  Inside the reaction vessel 12 of the quartz crystal thin film manufacturing apparatus 10 shown in FIGS. 1 and 2, a cylindrical shield 15 whose inner surface is made of aluminum oxide is provided. Usually, the reaction vessel 12 is heated to, for example, 550 to 600 ° C. in order to obtain a quartz crystal thin film having excellent crystallinity. Aluminum oxide forming the cylindrical shield 15 is a material that exhibits a high decomposition temperature and is chemically stable even at high temperatures (that is, a material that is inactive with respect to silicon oxide in a gas phase state). For this reason, the crystal produced | generated by reaction of raw material gas (in a gaseous state) is hard to adhere to the inner surface of a cylindrical shield. For this reason, the crystal produced | generated by reaction of source gas becomes easy to deposit on the surface of the board | substrate 14, and a quartz thin film can be efficiently formed on a board | substrate.

  As a material for forming the inner surface of the cylindrical shield, a material that is inactive with respect to a silicon oxide in a vapor state, for example, silicon carbide or trisilicon tetranitride is used in addition to the above aluminum oxide. Can do. For example, the cylindrical shield may have a structure in which a thin film of aluminum oxide, silicon carbide, or trisilicon tetranitride is formed on the inner surface of a quartz glass cylinder.

  In addition, as described above, in the conventional quartz thin film manufacturing apparatus, as the quartz crystal thin film is repeatedly manufactured on the substrate, the glass-like quartz that is the material of the reaction vessel reacts with the crystal attached to the inner surface of the reaction vessel. Thus, devitrification is likely to occur in the reaction vessel, and the mechanical strength of the reaction vessel gradually decreases due to devitrification, and eventually the reaction vessel may be cracked. For this reason, it is necessary to frequently replace the reaction vessel by managing its use time.

  The crystal thin film manufacturing apparatus 10 shown in FIG. 1 and FIG. 2 manufactures the crystal thin film on the substrate because the cylindrical shield 15 prevents the crystal from adhering to the inner surface of the reaction vessel 12 made of quartz glass. Even if it repeats, devitrification does not occur easily in a reaction container, and it is a practical thing with a low exchange frequency of a reaction container.

  In the crystal thin film manufacturing apparatus of the present invention, it is preferable that the tip opening of the second gas supply pipe 22 is disposed inside the cylindrical shield 15. Thereby, even if the supply amount of the source gas is the same, a larger amount of crystal is deposited on the surface of the substrate 14 so that the crystal thin film can be formed on the substrate efficiently (that is, at a high film formation rate). Become. In addition, the amount of quartz attached to the inner surface of the reaction vessel 12 made of quartz glass can be further reduced, and the replacement frequency of the reaction vessel can be further reduced.

As shown in FIG. 2, the distance (L ₂ ) between the tip opening of the second gas supply pipe 22 and the substrate 14 is larger than the distance (L ₁ ) between the tip opening of the first gas supply pipe 21 and the substrate 14. Short is preferred. When the first gas supply pipe 21 and the second gas supply pipe 22 are arranged in this way, vaporized tetraethoxysilane (tetraethoxysilane) supplied from the tip opening of the first gas supply pipe 21 to the inside of the reaction vessel 12. Can be allowed to react with oxygen supplied from the second gas supply pipe 22 after being sufficiently uniformly diffused inside the reaction vessel 12, so that the reaction can be uniformly performed on the substrate 14. Thick crystal thin films can be formed.

  Contrary to the above case, if the distance between the tip opening of the second gas supply pipe and the substrate is longer than the distance between the tip opening of the first gas supply pipe and the substrate, the tip of the first gas supply pipe The vaporized tetraethoxysilane supplied from the opening to the inside of the reaction vessel immediately contacts and reacts with oxygen supplied from the second gas supply pipe before being uniformly diffused inside the reaction vessel. A crystal thin film having a non-uniform thickness is easily formed on the substrate.

  As shown in FIG. 2, the second gas supply pipe 22 for supplying oxygen is composed of a supply pipe main body 22a and a tip opening unit 22b that is detachably attached to the tip of the supply pipe main body 22a. preferable. With such a configuration, the position of the tip opening of the second gas supply pipe 22 is adjusted by adjusting the position of the tip opening unit 22b attached to the supply pipe main body 22a, or the tip opening unit 22b is replaced with another shape. This makes it possible to make fine adjustments. Then, depending on the temperature distribution of the container 12 when the reaction container 12 of the crystal thin film manufacturing apparatus 10 is actually heated, or the size of the substrate 14 supported by the substrate holder 13, the tip opening of the second gas supply pipe 22 is opened. By finely adjusting the position of the portion, that is, the position where the silicon alkoxide and oxygen react, the crystallinity or thickness uniformity of the crystal thin film formed on the substrate 14 can be finely adjusted. Similarly, the first gas supply pipe 21 is also preferably composed of a supply pipe main body 21a and a tip opening unit 21b that is detachably attached to the tip of the supply pipe main body 21a.

  Further, the tip opening unit 22b of the second gas supply pipe 22 allows oxygen supplied from the second gas supply pipe 22 and silicon alkoxide supplied from the first gas supply pipe 21 to be on the surface of the substrate 14 or in the vicinity thereof. It is preferable to bend to bring them into contact with each other in position.

  It is preferable that the reaction vessel 12 further includes a third gas supply pipe 23 that supplies a gas containing a reaction accelerator from the outside to the inside of the reaction vessel 12. As the reaction accelerator, hydrogen chloride or ammonia is preferably used. By forming a gas containing a reaction accelerator from the third gas supply pipe 23 when forming the quartz thin film, the deposition rate of the quartz thin film on the surface of the substrate 14 can be increased.

  The reaction accelerator, for example, hydrogen chloride, breaks the bond between silicon and oxygen in the silicon alkoxide, and the silicon alkoxide and oxygen supplied into the reaction vessel from the tip opening of the second gas supply pipe 22. It is understood to accelerate the reaction (oxidation of silicon alkoxide) and increase the deposition rate of the quartz thin film. Examples of the reaction accelerator include an acidic gas typified by hydrogen chloride and a basic gas typified by ammonia.

  Hydrogen chloride (HCl) used as a reaction accelerator is, for example, a mixed valve in which hydrogen chloride is mixed with nitrogen used as a carrier gas at a ratio of 5% by volume from a gas cylinder 51a to a manual valve 52a, an air operated valve 54a, The gas is supplied into the reaction vessel 12 through the mass flow controller 55 a and the third gas supply pipe 23. The flow rate of the mixed gas is controlled by the mass flow controller 55a. The supply of the mixed gas to the reaction vessel 12 can be started or stopped by opening / closing the air operated valve 54a. The pressure sensor 53a is used for confirming the remaining amount of the mixed gas put in the gas cylinder 51a.

  It is also preferable that the reaction vessel 12 is further provided with a fourth gas supply pipe 24 for supplying a dilution gas (for example, nitrogen) for adjusting the concentration of the gas inside the reaction vessel 12. Nitrogen used as the dilution gas is supplied from the gas cylinder 51c to the inside of the reaction vessel 12 through the manual valve 52c, the air operated valve 54d, the mass flow controller 55d, and the fourth gas supply pipe 24, for example. The flow rate of nitrogen used as the dilution gas is controlled by the mass flow controller 55d. The supply of nitrogen used as a dilution gas to the reaction vessel 12 can be started or stopped by opening / closing the air operated valve 54d.

  As shown in FIG. 2, the reaction vessel 12 includes all gas supply pipes 21, 22, 23, and 24 at one end and a cylindrical vessel 12 a having an opening at the other end, and an exhaust port 11. And a lid portion 12b that is detachably attached to the opening of the cylindrical container 12a. Moreover, it is preferable that the cylindrical container 12a is arrange | positioned in the horizontal direction, and the board | substrate holder 13 is arrange | positioned so that the board | substrate 14 may be supported in the diagonal direction with respect to the wall surface of the cylindrical container 12a. With such a configuration, the flow of the raw material gas and the carrier gas inside the reaction vessel 12 becomes smooth, and the quality (eg, crystallinity and thickness uniformity) of the obtained crystal thin film is stabilized. Further, in order to prevent the leakage of the raw material gas and the carrier gas to the outside of the reaction vessel 12, the lid portion 12b is attached to the opening of the cylindrical vessel 12a via, for example, an O-ring 18.

  The reaction gas enters the reaction container 12 into the gap between the cylindrical container 12a and the lid portion 12b, and crystal is attached to the end surface of the cylindrical container on the lid portion side and the end surface of the lid portion on the cylindrical container side. In order to prevent this, an annular shield 16 is preferably provided. The annular shield 16 is made of, for example, a fluororesin.

  Further, in order to adjust the crystallinity of the quartz crystal thin film formed on the substrate, it is preferable that a heating tool is disposed outside the reaction vessel. The heating tool is preferably divided into a plurality of heating units along the direction from the first gas supply pipe of the reaction vessel toward the substrate holder, and the heating conditions of each heating unit are preferably controlled independently of each other. The heating tool of the crystal thin film manufacturing apparatus 10 shown in FIGS. 1 and 2 includes five heating units 31, 32, 33, 34, along the direction from the first gas supply pipe 21 of the reaction vessel 12 toward the substrate holder 13. Each heating unit is provided with a control device 41, 42, 43, 44, 45 for independently controlling each heating condition. As each of the five heating units 31, 32, 33, 34, 35, for example, a high-frequency induction heater or a resistance heater having an annular shape along the circumferential direction of the reaction vessel 12 is used.

  Thus, by arranging a plurality of heating units outside the reaction vessel, the temperature distribution inside the reaction vessel can be adjusted. For example, the temperature distribution inside the reaction vessel is supplied from the opening of the first gas supply pipe. It is possible to independently control the temperature of the silicon alkoxide, the temperature of the oxygen supplied into the reaction vessel from the opening of the second gas supply pipe, and the temperature of the substrate, and the crystal formed on the surface of the substrate. The crystallinity of the thin film can be easily adjusted.

  FIG. 3 is a cross-sectional view showing another configuration example of the quartz crystal thin film manufacturing apparatus of the present invention. The quartz crystal thin film manufacturing apparatus 60 of FIG. 3 is provided inside a reaction vessel 62 made of quartz glass having an exhaust port 11, a cylindrical shield 15 detachably mounted in the reaction vessel, and the cylindrical shield 15. A gas containing silicon alkoxide as a raw material from the outside to the inside of the reaction vessel 62, in which the front end openings are arranged with a space on the surface of the substrate 14 supported by the substrate holder with a space therebetween. The first gas supply pipe 21 for supplying oxygen, the second gas supply pipe 22 for supplying oxygen-containing gas, and the like. And the cylindrical shield 15 of the crystal thin film manufacturing apparatus 60 shown in FIG. 3 is formed, for example, by sintering aluminum oxide powder, and its inner surface is made of aluminum oxide.

  The reaction vessel 62 includes all the gas supply pipes 21, 22, 23, 24 at one end portion, a cylindrical vessel 62a having an opening at the other end portion, and an exhaust port 11. The lid 62b is detachably attached to the opening of the cylindrical container 62a. The substrate holder 63 is provided with a through hole for allowing the reaction gas to flow toward the exhaust port 11 and is mounted inside the reaction vessel 62 using, for example, an annular substrate holder fixture 67 made of quartz glass. ing.

  The crystal thin film manufacturing apparatus 60 of FIG. 3 has the same configuration as that of FIG. 2 except that the cylindrical container 62a of the reaction container 62 is arranged in the vertical direction and the substrate holder 63 is arranged to support the substrate 14 in the horizontal direction. This is the same as the quartz crystal thin film manufacturing apparatus 10. When the cylindrical container is arranged in the vertical direction as described above, a space for installing the crystal thin film manufacturing apparatus is reduced.

  FIG. 4 is a cross-sectional view showing still another configuration example of the quartz crystal thin film manufacturing apparatus of the present invention. The crystal thin film manufacturing apparatus 70 shown in FIG. 4 has a structure in which a heating tool disposed outside the reaction vessel 12 is divided into three heating units 31, 32, 33, and a partition wall inside the reaction vessel 12. 1 is the same as the crystal thin film manufacturing apparatus 10 of FIG.

  Usually, the temperature of the end portion of the reaction vessel 12 is more likely to be lower than that of the central portion. For this reason, the low-temperature gas cooled at each end of the reaction vessel 12 circulates from the lower end of the reaction vessel to the lower center, the upper center, and the upper end of the reaction vessel to easily generate convection. Thus, when convection occurs inside the reaction vessel 12, the mixing ratio of silicon alkoxide and oxygen or the temperature of the substrate fluctuates, making it difficult to obtain a quartz thin film with stable quality.

  In order to suppress the occurrence of such convection in the reaction vessel, the crystal thin film manufacturing apparatus 70 of FIG. 4 includes a tip opening of the first gas supply pipe 21, a tip opening of the second gas supply pipe 22, and a substrate. A pair of partition walls 91 and 92 each having a through hole through which a gas flows are arranged inside the reaction vessel with a space between each other with the holder 13 therebetween. For example, the partition wall 92 inhibits the flow of gas from the lower end of the reaction vessel to the lower center of the reaction vessel and the flow of gas from the upper upper portion to the upper end of the reaction vessel, thereby suppressing the occurrence of convection in the reaction vessel. . By providing such partition walls 91 and 92, fluctuations in the mixing ratio of silicon alkoxide and oxygen or the substrate temperature can be suppressed, and a quartz thin film can be manufactured with stable quality.

  As shown in FIG. 4, a partition wall 93 may be further arranged inside the reaction vessel 12. If the number of partition walls arranged in the reaction vessel is too large, it takes time to assemble the crystal thin film manufacturing apparatus. Therefore, the number of partition walls to be added is preferably 1 to 4.

  5 and 6 are views of the partition wall 91 and the partition wall 92 shown in FIG. 4 as viewed from the left side of the drawing. As shown in FIG. 5, the partition wall 91 includes a gas containing a reaction accelerator supplied from the first gas supply pipe 21, the second gas supply pipe 22, and the third gas supply pipe 23 into the reaction vessel, and A through hole 91a through which the dilution gas supplied from the fourth gas supply pipe 24 into the reaction vessel passes is formed. As shown in FIG. 6, the partition wall 92 is formed with through holes 92a through which the silicon alkoxide-containing gas, oxygen-containing gas, reaction accelerator-containing gas, and diluent gas remaining after the formation of the crystal thin film are passed. Similarly, a through-hole 93a is formed in the partition wall 93 shown in FIG. Each of the partition walls 91, 92, and 93 is made of, for example, quartz glass.

  The crystal thin film manufacturing apparatus 70 shown in FIG. 4 can be assembled, for example, according to the following procedure. First, a reaction vessel 12 including a cylindrical vessel 12a having gas supply pipes 21, 22, 23, and 24 and a lid portion 12b is prepared. Next, the partition wall 91 and the cylindrical support tool 102 are inserted from the opening of the cylindrical container 12a, and the partition wall 91 is supported by the support tool 101 fixed in the cylindrical container and the cylindrical support tool 102. And placed inside the reaction vessel 12. The support tool 101 is set in a curved shape along the inner surface of the reaction vessel 12. Similarly, the cylindrical shield 15, the partition wall 93, the cylindrical support member 103, the partition wall 92, and the cylindrical support member 104 in which the substrate holder 13 is disposed inside are inserted in this order inside the cylindrical container 12a. To do. Then, the crystal thin-film manufacturing apparatus 70 can be assembled by attaching the lid 12b to the opening of the cylindrical container 12a via the O-ring 18 and temporarily fixing them with an appropriate jig (not shown). it can.

  Each of the above supports 101, 102, 103, 104 is made of, for example, quartz glass. Each support may be formed of a material that has an inner surface that is inactive with respect to silicon oxide in a gas phase, as in the case of the cylindrical shield 15.

  For example, when a buffer layer made of an amorphous crystal thin film is formed on a substrate according to the description in Patent Document 1 using the crystal thin film manufacturing apparatus of the present invention, a crystal crystal having excellent crystallinity is formed on the buffer layer. A thin film can be formed, and in accordance with the contents of Non-Patent Document 1, two buffer layers each made of a quartz thin film on the substrate (specifically, the crystallinity of the quartz thin film used as the upper buffer layer is When the crystallinity of each buffer layer is adjusted to be higher than the crystallinity of the crystal thin film used as the lower buffer layer, the AT cut surface is preferentially oriented on these buffer layers. A quartz crystal thin film can be formed.

  As the buffer layer, for example, the same silicon alkoxide and oxygen at a substrate temperature lower (for example, 20 to 200 ° C.) lower than the substrate temperature at the time of forming the quartz crystal thin film by the reaction of silicon alkoxide and oxygen. Can be used. When forming the two buffer layers, the substrate temperature is lower (for example, 10 to 100 ° C. lower) than the substrate temperature when the lower buffer layer is formed (for example, in the range of 40 to 530 ° C.). It is preferable to form the upper buffer layer at the substrate temperature), and it is more preferable to adjust the crystallinity by annealing after the formation of each buffer layer. The substrate temperature when forming the quartz crystal thin film on these buffer layers is particularly preferably in the range of 550 to 600 ° C.

  Further, as the substrate on which the quartz crystal thin film is formed, an Si substrate, a GaAs substrate, or a sapphire substrate is preferably used, and a sapphire substrate having a (110) A plane is particularly preferable.

  As described above, the quartz crystal thin film manufacturing apparatus of the present invention can be advantageously used for efficiently producing a quartz crystal thin film, particularly a quartz crystal thin film with an AT cut surface preferentially oriented, and the reaction container can be replaced frequently. Low practical.

It is a figure which shows the structural example of the crystal thin film manufacturing apparatus of this invention, and the supply method of the raw material gas to this manufacturing apparatus. It is sectional drawing of the crystal thin film manufacturing apparatus shown in FIG. It is sectional drawing which shows another structural example of the crystal thin film manufacturing apparatus of this invention. It is sectional drawing which shows another example of a structure of the crystal thin film manufacturing apparatus of this invention. It is the figure which looked at the partition 91 with which the crystal thin film manufacturing apparatus of FIG. 4 is provided from the left side of the figure. It is the figure which looked at the partition 92 with which the crystal thin film manufacturing apparatus of FIG. 4 is provided from the left side of the figure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Quartz thin film manufacturing apparatus 11 Exhaust port 12 Reaction container 12a Cylindrical container 12b Cover part 13 Substrate holder 14 Substrate 15 Cylindrical shield 16 Annular shield 17 Substrate holder fixture 18 O-ring 19 Vaporizer 21 First gas supply pipe 21a Supply pipe body 21b Tip opening unit 22 Second gas supply pipe 22a Supply pipe body 22b Tip opening unit 23 Third gas supply pipe 24 Fourth gas supply pipe 31, 32, 33, 34, 35 Heating unit 36 Heating tool 41, 42 , 43, 44, 45 Heating unit control device 46 Heating tool control device 51a, 51b, 51c Gas cylinder 52a, 52b, 52c Manual valve 53a, 53b, 53c Pressure sensor 54a, 54b, 54c, 54d Air operated valve 55a, 55b, 55c, 55d, 55e Mass flow controller 60 Crystal thin film manufacturing apparatus 62 Reaction container 62a Cylindrical container 62b Lid 63 Substrate holder 67 Substrate holder fixture 70 Crystal thin film manufacturing apparatus 91, 92, 93 Partition 91a, 92a, 93a Through hole 101, 102, 103, 104 Support

Claims (14)

  A reaction vessel made of quartz glass having an exhaust port, a cylindrical shield detachably mounted in the reaction vessel, a substrate holder provided inside the cylindrical shield, and the surface of the substrate supported by the substrate holder or A gas containing raw material silicon alkoxide is supplied from the outside to the inside of the reaction vessel, which is disposed with a front end opening facing each other in an area around the substrate on a plane including the substrate surface. A gas supply pipe and a second gas supply pipe for supplying an oxygen-containing gas, wherein the inner surface of the cylindrical shield is formed of a material that is inert to silicon oxide in a gas phase. A crystal thin film manufacturing apparatus characterized by comprising:   2. The crystal thin film manufacturing apparatus according to claim 1, wherein the material inert to the silicon oxide in the gas phase is aluminum oxide, silicon carbide, or trisilicon tetranitride.   The crystal thin film manufacturing apparatus according to claim 1, further comprising a third gas supply pipe for supplying a gas containing a reaction accelerator from the outside to the inside of the reaction container.   The crystal thin film manufacturing apparatus according to claim 3, wherein the reaction accelerator is hydrogen chloride or ammonia.   The reaction vessel has all the gas supply pipes at one end and a cylindrical vessel having an opening at the other end and an exhaust port, and is detachably attached to the opening of the cylindrical vessel. The crystal thin film manufacturing apparatus according to any one of claims 1 to 4, wherein the cylindrical shielding body is mounted on a cylindrical container.   The crystal thin film manufacturing apparatus according to claim 1, wherein a distal end opening of the second gas supply pipe is disposed inside the cylindrical shield.   The crystal thin film manufacturing apparatus according to claim 1, wherein a distance between the tip opening of the second gas supply pipe and the substrate is shorter than a distance between the tip opening of the first gas supply pipe and the substrate.   The crystal thin film manufacturing apparatus according to claim 1, wherein the second gas supply pipe includes a supply pipe main body and a tip opening unit that is detachably attached to a tip of the supply pipe main body.   The crystal thin film manufacturing apparatus according to claim 8, wherein the tip opening unit is bent.   The crystal thin film manufacturing apparatus according to claim 1, wherein the first gas supply pipe includes a supply pipe main body and a tip opening unit that is detachably attached to a tip of the supply pipe main body.   6. The crystal thin film manufacturing apparatus according to claim 5, wherein the cylindrical container is disposed in a horizontal direction, and the substrate holder is disposed so as to support the substrate in an oblique direction with respect to the wall surface of the cylindrical shield.   The crystal thin film manufacturing apparatus according to claim 1, wherein a heating tool is disposed outside the reaction vessel.   The heating tool is divided into a plurality of heating units along a direction from the first gas supply pipe of the reaction vessel toward the substrate holder, and heating conditions of each heating unit are controlled independently of each other. Crystal thin film manufacturing equipment.   Provided with a through hole through which the gas is circulated, the tip opening of the first gas supply pipe, the tip opening of the second gas supply pipe, and the substrate holder are arranged inside the reaction container with a space therebetween. The crystal thin film manufacturing apparatus according to claim 12, further comprising a pair of partition walls.

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