JP2015110812A - Method of manufacturing lead compound thin film, and crucible - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead compound thin film of good quality.SOLUTION: A vapor deposition device is used that includes: a chamber; a plurality of vapor deposition sources which are arranged in the chamber, one of the vapor deposition sources including a crucible formed in a container shape of a member which is supplied with electric power to generate heat such that a side face part becomes higher in temperature than a bottom face part when the electric power is supplied, a lead raw material accommodated in the crucible, and a lead vapor deposition source having an electron gun irradiating the lead raw material accommodated in the crucible with an electron beam; and a substrate which is arranged in the chamber above the vapor deposition sources. While the electric power is supplied to the crucible of the lead vapor deposition source so as to heat the side face of the crucible to a higher temperature than the bottom face part, the lead raw material of the lead vapor deposition source is irradiated with the electron beam so as to vaporize the lead raw material, and a plurality of kinds of vapor deposition raw material are vaporized from the plurality of vapor deposition sources except the lead vapor deposition source so as to vapor-deposit a lead compound thin film on a surface of the substrate.

Description

  The present invention relates to a method for producing a compound thin film containing lead by a physical vapor deposition method, and a crucible used for the production method.

  Lead-containing multi-element oxide ferroelectrics such as lead zirconate titanate (PZT) and lead lanthanum zirconate titanate (PLZT) have excellent piezoelectricity, pyroelectricity, electro-optical properties, etc. It is applied to various electronic devices. Such a multi-element oxide ferroelectric can be formed on a substrate using a physical vapor deposition method such as a vacuum vapor deposition method or an ion plating method. For example, in Patent Documents 1 and 2, various source gases evaporated from an evaporation source are activated by high-density plasma generated by a pressure gradient arc discharge plasma gun, and a multi-component oxide strong oxide is formed on a substrate in an oxygen atmosphere. An arc discharge reactive ion plating method for depositing a thin film made of a dielectric has been proposed.

  In such a physical vapor deposition method, the evaporation material is generally melted and evaporated using an electron beam. In Patent Document 3, in order to suppress splash (bumping) that may occur when the evaporation material is melted / evaporated, the evaporation material is irradiated with an electron beam while the evaporation material is uniformly heated by a heater or the like. A method for melting and evaporating the evaporation raw material has been proposed. The bumping of the evaporation material is considered to occur when a gas (air or the like) contained in the evaporation material is released from the heated and melted Pb material.

Japanese Patent No. 4138196 JP 2011-204776 A JP 09-143694 A

  When the evaporating raw material bumps, the vaporized evaporating raw material scatters violently, so that droplets of the evaporating raw material adhere to the thin film to be formed, and a small lump (particle) made of the evaporating raw material can be formed. Since such particles may deteriorate the crystallinity of the thin film, it is preferable to reduce the number of particles (or particle density) in the thin film as much as possible.

  Further, according to the study by the present inventor, it has been found that lead raw materials used when vapor-depositing a lead compound thin film such as PZT are particularly prone to bumping.

  An object of the present invention is to provide a high-quality lead compound thin film.

  According to one aspect of the present invention, a chamber, a plurality of evaporation sources disposed in the chamber and including a plurality of types of evaporation materials including lead, and in the chamber above the plurality of evaporation sources A lead compound thin film manufacturing method using a vapor deposition apparatus comprising: a substrate holder capable of holding a substrate, wherein: a) a power supply as one of the plurality of evaporation sources It is composed of a member that generates heat, has a container-like shape, and when power is supplied, the side part is higher in temperature than the bottom part, the lead raw material contained in the crucible, and contained in the crucible Preparing a lead evaporation source including an electron gun for irradiating the lead raw material with an electron beam and a power source for supplying electric power to the crucible; b) disposing a substrate on the substrate holder; c ) Ruth of the lead evaporation source While supplying the power to the crucible and heating the side part of the crucible to a temperature higher than the bottom part, the lead raw material of the lead evaporation source is irradiated with an electron beam to evaporate the lead raw material, and the lead evaporation source is removed. There is provided a method for producing a lead compound thin film comprising the steps of evaporating a plurality of types of evaporation materials from a plurality of evaporation sources and depositing a lead compound thin film on the substrate surface.

  According to another aspect of the present invention, it is configured by a member that generates heat when supplied with electric power, and has a shape including a container part and a handle part projecting outside the container part, and is supplied with electric power from the handle part. Thus, a crucible in which the side surface of the container part is hotter than the bottom surface is provided.

  The bumping or scattering amount of the lead raw material is suppressed, and a high-quality lead compound thin film can be obtained.

FIG. 1 is a schematic side view showing a configuration example of an arc discharge reaction type ion plating apparatus. FIG. 2A is a schematic side view showing a configuration example of a lead evaporation source, and FIGS. 2B and 2C are a plan view and a cross-sectional view showing a structure of a crucible used for the lead evaporation source. FIG. 3 is a flowchart showing a method for producing a lead compound thin film.

  Hereinafter, a method for forming a PZT film as a lead compound thin film will be described. The lead compound thin film is not limited to the PZT film but may be a PLZT film or the like.

  FIG. 1 is a schematic side view showing an arc discharge reactive ion plating (ADRIP) apparatus 100 used when producing a PZT film. The ADRIP apparatus 100 is configured such that a substrate holder 104, various evaporation sources 106 to 108, a gas supply mechanism 109, a plasma gun 110, a sub chamber 120, and the like are attached to a reaction chamber (main chamber) 101.

The reaction chamber 101 is connected to a vacuum exhaust device 130, and the inside of the reaction chamber 101 can be evacuated to a high vacuum (a vacuum degree of 1 × 10 ⁻⁴ Pa or higher and a pressure of 1 × 10 ⁻⁴ Pa or lower).

  A rotation shaft 102 is provided through the upper surface of the reaction chamber 101, and a substrate holder 104 provided with a radiant heating type heater 103 is connected to the rear surface. The substrate holder 104 is configured to hold the substrate 105.

Further, a reaction gas supply mechanism 109 is provided through the upper surface of the reaction chamber 101, and a reaction gas such as oxygen (O ₂ ) can be supplied from the reaction gas supply mechanism 109 to the surface of the substrate 105.

  At the bottom of the reaction chamber 101, a lead (Pb) evaporation source 106, a zirconium (Zr) evaporation source, and a titanium (Ti) evaporation source 108 are provided. Each of the various evaporation sources 106 to 108 has a configuration in which a crucible is filled with Pb, Zr, and Ti raw materials. Various evaporation raw materials are melted and evaporated by, for example, electron beam irradiation.

  A plasma gun 110 having an anode, a cathode, a magnetic field generating coil, and the like is provided on the side surface of the reaction chamber 101. The plasma gun 110 ionizes and activates an inert gas (discharge gas) such as Ar or He by arc discharge. Then, the plasma 118 is led out between the substrate 105 and the various evaporation sources 106 to 108 in the chamber 101 by the pressure gradient of the magnetic field / discharge gas generated by the magnetic field generating coil.

  A sub chamber 120 is provided on the side surface of the reaction chamber 101. The sub-chamber 120 can be evacuated to a high vacuum and can accommodate the substrate 105. By including the sub-chamber 120 that can be evacuated to a high vacuum, the substrate 105 can be taken in and out of the reaction chamber 101 while the inside of the reaction chamber 101 is maintained at a high vacuum.

  2A is a schematic cross-sectional view showing the configuration of the Pb evaporation source 106, and FIGS. 2B and 2C are a plan view and a cross-sectional view showing the crucible 10 used in the Pb evaporation source 106. FIG. The Zr evaporation source 107 and the Ti evaporation source 108 may have the same configuration as that of the Pb evaporation source 106, but are not particularly limited to these configurations, and may have a generally known evaporation source configuration.

  As shown in FIG. 2A, the Pb evaporation source 106 mainly includes a crucible 10, a power supply terminal 20, a power supply 30, and a heat insulating member 40. The crucible 10 is filled with a Pb raw material 13.

  As shown in FIGS. 2B and 2C, the crucible 10 has a bottom surface portion 11a (having a diagonal pattern with a relatively narrow pitch in FIG. 2B) and a side surface portion 11b (an oblique line with a relatively wide pitch in FIG. 2B). The shape includes a cylindrical container portion 11 configured with a pattern) and a pair of handle portions (projecting portions) 12 projecting outward from the side surface portion 11 b of the container portion 11. The height H of the container part 11 is about 15 mm to 25 mm, and the diameter L is about 30 mm to 60 mm. Further, the thickness d1 of the bottom surface portion 11a is thicker than the thickness d2 of the side surface portion 11b and is thinner than the thickness d3 of the handle portion 12 (d2 <d1 <d3). For example, the thickness d2 of the side surface portion 11b is ½ or less of the thickness d1 of the bottom surface portion 11a, and the thickness d3 of the handle portion 12 is 4/3 or more of the thickness d1 of the bottom surface portion 11a. The crucible 10 is composed of a member that generates heat when supplied with power, such as carbon (C) or silicon carbide (SiC).

  As shown in FIG. 2A, the crucible 10 having such a configuration is arranged such that the main part of the container part 11 is surrounded by the heat insulating member 40. The crucible 10 is supplied with power from a power source 30 via a power terminal 20 that is electrically connected to the handle 12. The handle portion 12 of the crucible 10 and the power supply terminal 20 are connected via an appropriate means such as a screw or a spring.

  The thermocouple 31 that is disposed on the lower surface of the crucible 10 and detects the temperature of the crucible 10, and the power supplied by the power source 30 (such as output voltage) is controlled based on the temperature of the crucible 10 detected by the thermocouple 31. A control device 32 may be provided. The power supply 30, the thermocouple 31, and the control device 32 constitute a feedback system that can maintain the temperature of the crucible 10 at a constant temperature.

  When electric power is supplied to the crucible 10, that is, when current flows from the one handle portion 12 through the container portion 11 (the bottom surface portion 11a and the side surface portion 11b) to the other handle portion 12, the crucible 10 generates heat. When the temperatures of the bottom surface portion 11a, the side surface portion 11b, and the handle portion 12 when power is supplied are T1 to T3, respectively, the thickness relationship between the bottom surface portion 11a, the side surface portion 11b, and the handle portion 12 (d2 <d1 <d3), In other words, from the relationship of resistivity, the temperature relationship is T3 <T1 <T2. The Pb raw material 13 accommodated in the crucible 10 can be preliminarily heated by the heat generated by the crucible 10. In addition, the temperature of the crucible 10 can be controlled to a constant temperature by providing a feedback system including the thermocouple 31 and the control device 32.

  The Pb evaporation source 106 further includes an electron gun 50. The electron beam 51 emitted from the electron gun 50 is accelerated by an electric field, focused and deflected by a magnetic field, and irradiated to the Pb raw material 13 in the crucible 10. The electron emission method of the electron gun 50 may be a thermionic emission type or a field emission type. By irradiation with the electron beam 51, the Pb raw material 13 can be melted and evaporated.

  FIG. 3 is a flowchart showing the film forming process of the PZT film. The PZT film forming process will be described below with reference to the configuration of the ADRIP apparatus 100 shown in FIG. 1 and the configuration of the Pb evaporation source 106 shown in FIG.

First, before disposing the substrate 105 on the substrate holder 104, the inside of the reaction chamber 101 is evacuated to a high vacuum of, for example, 1 × 10 ⁻⁴ Pa or more (step S101). At this time, the substrate 105 is accommodated in the sub-chamber 120, and the sub-chamber 120 is also evacuated to the same degree of vacuum as in the reaction chamber 101.

  Next, the substrate 105 is moved from the sub-chamber 120 to the reaction chamber 101 and disposed on the substrate holder 104 in the reaction chamber 101 (step S102). Subsequently, the substrate 105 is heated by the radiant heating type heater 103 so that the temperature of the substrate 105 becomes 500 ° C. (step S102).

  After the temperature of the substrate 105 reaches about 500 ° C., Ar gas is introduced into the plasma gun 118 at 1 sccm to 100 sccm and He gas is introduced at 5 sccm to 300 sccm, and a DC voltage is applied between the cathode and the anode of the plasma gun 110. An arc discharge plasma 118 is generated. Then, the plasma 118 is introduced into the chamber 101 by the pressure gradient of the magnetic field / discharge gas generated by the magnetic field generating coil (step S103). Subsequently, 50 sccm to 400 sccm of oxygen gas is introduced from the reaction gas supply mechanism 109 to generate high-density oxygen plasma and oxygen active species (step S104).

  Thereafter, Pb, Zr, and Ti raw materials are evaporated from the various evaporation sources 106, 107, and 108, respectively (step S105, step S106). In particular, in the Pb raw material evaporation step S106, power is supplied to the crucible 10 by the power source 30, and the Pb raw material 13 is irradiated with the electron beam 51 while heating at least the side surface portion 11b to a temperature higher than the bottom surface portion 11a. 13 is evaporated (see FIG. 2). At this time, the temperature of the crucible 10 is controlled to be a constant temperature by a feedback system including the thermocouple 31 and the control device 32.

  The evaporation amounts of various evaporation materials are such that the evaporation amount of Pb is up to 10 times the total evaporation amount of Zr and Ti, and the evaporation amounts of Zr and Ti are substantially equal. It is preferable to control. The amount of evaporation of the various evaporation materials can be controlled by adjusting the intensity of the electron beam applied to the various materials, and can be detected and monitored by using a crystal oscillator type film thickness sensor or the like.

  Various raw material vapors evaporated from the evaporation sources 106, 107 and 108 are activated when passing through the plasma 118 and reach the substrate 105. By introducing oxygen gas from the reactive gas supply mechanism 109, high-density oxygen plasma and active species of oxygen are generated and react with various raw material vapors in the vicinity of the substrate 105 to form a PZT film 105a. As a result, a PZT film 105 a having a perovskite crystal structure is formed on the surface of the substrate 105 held by the substrate holder 104.

  According to the study of the present inventor, it is known that the Pb raw material is more likely to cause bumping compared to the Zr raw material and the Ti raw material. When the Pb raw material 13 scatters due to bumping, the splash of the Pb raw material 13 adheres to the substrate 105. Such bumping occurs when, in the Pb raw material evaporation step S106, when the side surface of the crucible 10 is at a relatively low temperature, the vapor of the evaporated Pb raw material 13 is deposited on the side surface of the crucible 10 to form a solid. One cause is considered to be caused by falling on the material in the crucible 10.

  When the side surface portion 11b of the crucible 10 is at a high temperature, specifically, a temperature higher than the temperature at which Pb is melted, the solid material is prevented from being deposited on the side surface portion 11b of the crucible 10, and even if precipitation occurs. The adhering Pb solid matter is considered to prevent the bumping by falling into the crucible because it is remelted and re-evaporates from the side surface portion 11b. For this reason, it is thought that the Pb splash adhering to the board | substrate 105 after adhering to the side part 11b of the crucible 10 reduces. Further, it is considered that this reduces the total amount of Pb droplets adhering to the substrate 105 and also reduces the Pb particle density of the PZT film 105a to be formed.

  Further, in the Pb raw material evaporation step S106, not only the side surface portion 11b of the crucible 10 but also the bottom surface portion 11a is heated to irradiate the Pb raw material 13 with an electron beam while heating the Pb raw material 13 as a whole. The cause of bumping may be due to the gas dissolved in the Pb raw material 13, but by this, a sudden temperature change or a significant temperature distribution of the Pb raw material 13 is relaxed, and the bumping of the Pb raw material 13 is suppressed. By suppressing the bumping of the Pb raw material 13, it is considered that the amount of the scattered Pb raw material 13 is reduced, and the Pb particle density in the PZT film 105a is further reduced. In addition, it is preferable that the handle part 12 of the crucible 10 is as low as possible from the viewpoint of suppressing thermal fatigue and thermal deterioration of the power supply terminal 20 connected thereto.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not restrict | limited to these. For example, the thin film formed on the substrate surface is not limited to the PZT film, but may be a compound thin film containing Pb. The thin film forming method is not limited to the ADRIP method, and any method may be used as long as it is a method of melting and evaporating the Pb raw material, such as a vacuum evaporation method or an ion plating method. It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 ... Crucible, 11 ... Container part, 11a ... Bottom part, 11b ... Side part, 12 ... Handle part, 13 ... Lead raw material, 20 ... Power supply terminal, 30 ... Power supply, 40 ... Thermal insulation member, 50 ... Electron gun, 51 ... Electron beam, 100 ... ADRIP apparatus, 101 ... Reaction chamber (main chamber), 102 ... Rotating shaft, 103 ... Heater, 104 ... Substrate holder, 105 ... Substrate, 105a ... Thin film (PZT film), 106-108 ... Evaporation source, 109 ... reactive gas supply mechanism, 110 ... plasma gun, 118 ... plasma, 120 ... subchamber, 130 ... evacuation apparatus.

Claims (7)

A chamber, a plurality of evaporation sources provided in the chamber and including a plurality of types of evaporation materials containing lead, and disposed in the chamber and above the plurality of evaporation sources to hold a substrate. A substrate holder, and a method for producing a lead compound thin film using a vapor deposition apparatus comprising:
a) As one of the plurality of evaporation sources,
A crucible composed of a member that generates heat when power is supplied, has a container-like shape, and when the power is supplied, the side surface portion has a higher temperature than the bottom surface portion,
Lead raw material contained in the crucible,
An electron gun that irradiates the lead raw material contained in the crucible with an electron beam; and
A power supply for powering the crucible,
Preparing a lead evaporation source comprising:
b) disposing a substrate on the substrate holder;
c) While supplying electric power to the crucible of the lead evaporation source and heating the side surface of the crucible to a temperature higher than that of the bottom surface, the lead material of the lead evaporation source is irradiated with an electron beam to evaporate the lead material. Evaporating a plurality of types of evaporation materials from the plurality of evaporation sources excluding the lead evaporation source, and depositing a lead compound thin film on the substrate surface;
A method for producing a lead compound thin film comprising:   The crucible has a cylindrical shape with an open top surface, a thickness of a side surface portion is less than half of a thickness of a bottom surface portion, a height of 15 mm to 25 mm, and a diameter of 30 mm to 60 mm. Manufacturing method of lead compound thin film. The crucible further includes a pair of overhanging portions that are coupled to the outside of the side surface portion and are thicker than the thickness of the bottom surface portion,
The method for producing a lead compound thin film according to claim 2, wherein the power source is electrically connected to a pair of overhang portions of the crucible.   The method for producing a lead compound thin film according to any one of claims 1 to 3, wherein, in the step c), a temperature of a side surface portion of the crucible is higher than a temperature at which the lead raw material melts.   The plurality of evaporation sources include, in addition to the lead evaporation source, a zirconium evaporation source including a zirconium raw material and a titanium evaporation source including a titanium raw material, and the lead compound thin film is a PZT film. A method for producing a lead compound thin film according to item 1.   It is composed of a member that generates heat when supplied with electric power, and has a shape including a container part and a handle part projecting outside the container part, and by supplying electric power from the handle part, the side surface of the container part is A crucible that is hotter than the bottom.   The container portion has a cylindrical shape with an open top surface, a thickness of a side surface is half or less of a thickness of a bottom surface, a height of 15 mm to 25 mm, and a diameter of 30 mm to 60 mm. Crucible.

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