JPH04311562A - Method and equipment for manufacturing film by ion bream method - Google Patents

Abstract

PURPOSE:To offer a method an equipment for forming a high quality thin film covering a whole surface of a substrtate by highly controlling ion reaching to the substrate and remarkably enlarging ion current. CONSTITUTION:A substrate holder 35 holds a discoild substrate bias electrode 36 at its center and ring-shaped substrate bias electrode 37 in its periphery part. Ion density distribution reaching to the surface of the substrate 32 is precisely controlled by changing electric potential of plural substrate bias electtrode 36 and 37 installed at the substrate holder using DC electric source device 38 and 39 and controlling electrical field distribution on the substrate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion beam film forming method and an ion beam film forming apparatus in cluster ion beam evaporation used for manufacturing highly functional thin film devices.

0002

[Prior Art] Conventionally, a cluster ion beam film forming apparatus used for cluster ion beam evaporation, which forms a highly functional thin film by heating and evaporating a solid substance at room temperature and depositing it on a substrate to be evaporated, is used, for example. As disclosed in Japanese Patent No. 54-9592, it had a configuration as shown in FIG. That is, a cluster beam generation section 1, a cluster beam ionization section 2, and a cluster ion beam acceleration section 3.
, and a substrate holder 4 that holds a substrate to be deposited on which a deposition substance is to be deposited.

First, the cluster beam generating section 1 will be explained. A cylindrical crucible (Knudsen cell) 6 having a nozzle 5 formed in the center of its upper surface is heated by a resistance heater (heating means) 7 installed around the outer periphery of the crucible 6. 8 is a crucible heating power source for supplying electric power to the resistance heating type heater 7 for heating. The crucible 6 generally has a single-layer structure made of carbon, tungsten, or the like.

Next, the configuration of the cluster beam ionization section 2 will be explained. 9 is a thermionic emission filament for ionization, 10 is a power source for heating the ionization thermionic emission filament 9 for supplying power to and heating the ionization thermionic emission filament 9, and 11 is a mesh-like thermionic extraction grid 12 and ionization. Thermionic emission filament 9
This is a thermionic extraction power source for extracting thermionic electrons from the thermionic emission filament 9 for ionization heated to a high temperature by applying a voltage during this period to form an electron shower. 13 is a heat shield arranged so as to enclose the thermionic emission filament 9 for ionization.

Next, the configuration of the cluster ion beam accelerator 3 will be explained. Reference numeral 14 denotes an acceleration electrode as a means for accelerating ionized clusters, and an acceleration power source 15 applies a voltage between the ionization part and the grid 12 for extracting thermionic electrons as shown. The cluster ion beam accelerated by the accelerating electrode 14 collides with the substrate 16 to deposit a thin film. Note that the substrate 16 is held by a substrate holder 17. The substrate holder 17 has a heater and a cooling channel (not shown) inside thereof, and can control the temperature of the substrate 16 according to the function required of the thin film.

The operation of the apparatus having the above configuration is as follows. After replenishing the vapor deposition material 18 into the crucible 6, a vacuum chamber (not shown) containing the crucible 6 is set to a predetermined pressure (degree of vacuum) P, and the vapor deposition material 18 is heated by the resistance heater 7. The vapor 1 of the vapor deposited substance 18 inside the crucible is evaporated.
Increase the pressure of 9.

When the vapor 19 of the vapor deposition substance 18 is ejected from the nozzle 5 in the direction of the arrow in the figure, it expands adiabatically due to the pressure difference between the vacuum chamber and the crucible, and is supercooled. Therefore, steam 1
9 is condensed and becomes a beam of a lumpy atomic group in which 500 to 2000 atoms are loosely bonded to each other, that is, a cluster beam, which flies toward the substrate. At this time, in order to form clusters efficiently, it is necessary to maintain the ratio of the pressure P0 inside the crucible to the pressure P of the vacuum chamber at P0/P>104 to 105. For example, the pressure P of the vacuum chamber is 10-6 Torr.
When r, the pressure P0 inside the crucible is 10-2 or more, in fact, P0=0.1 to 1 Torr.

Next, in the ionization section 2, the cluster beam is showered with electrons that have passed through the extraction grid 12 from the thermionic emission filament 9 for ionization to ionize one atom among the constituent atoms of the cluster. A beam of cluster ions is formed. Positive (plus)
The cluster ions ionized are accelerated by the electric field formed by the accelerating electrode 14, collide with the substrate 16, and
A thin film of vapor deposition material is formed on 6.

Unlike other ion beam deposition methods, this cluster ion beam deposition method allows transport of a low-charge, large-mass ion beam, so it can be used to deposit films on insulating substrates with less charge influence. can.

[0010] Furthermore, according to the cluster ion beam film forming method, the adhesion, crystallinity, and orientation of the film are generally good due to the effects of high physical kinetic energy possessed by clusters and chemical energy possessed by ions. , a high-density and homogeneous film can be obtained, but in this case, ionization, which is a characteristic of cluster ion beam deposition, is an important requirement. Therefore,
Film quality was controlled by adjusting the amount of electrons extracted from the ionization section and the accelerating voltage to adjust the amount of ions reaching the substrate.

However, in the configuration of the conventional cluster ion beam film forming apparatus, when controlling the amount and kinetic energy of ions reaching the substrate by adjusting the accelerating voltage,
There was a problem in that the current density distribution of ions reaching the substrate varied depending on the value of the accelerating voltage. That is, the amount of ions reaching the center and the periphery of the membrane differed greatly depending on the value of the accelerating voltage, so the quality of the film was different between the center and the periphery of the membrane. Furthermore, the control range for the amount and kinetic energy of ions reaching the substrate was narrow.

[0012] In the conventional film forming method using ions, in order to control the amount of ions reaching the substrate, it is common to simply bias the entire substrate to a uniform negative voltage with respect to ground potential. Met. However, with this conventional method, it was not possible to control the current density distribution of ions reaching the substrate. Furthermore, the distribution of ions reaching the substrate could not be measured, making it difficult to control the film quality.

[0013]

[Problems to be Solved by the Invention] As described above, in the conventional technology, it is not possible to control the current density distribution of ions reaching the substrate when changing the film forming conditions. There is a problem in that the film quality and thickness are different between the center and the periphery of the film.

The present invention solves the above-mentioned problems, and is an ion beam manufacturing method that has high controllability of ions reaching the substrate, has a significantly large ion current value, and can form a high-quality thin film over the entire surface of the substrate. The object of the present invention is to provide a film method and an ion beam film forming apparatus.

[0015]

[Means for Solving the Problems] In order to achieve the above object, the ion beam film forming method according to the present invention heats a vapor deposition material in a crucible to evaporate the vapor deposition material, and the evaporated vapor of the vapor deposition material is transferred to the crucible. When the evaporated vapor is ejected into the vacuum chamber from a nozzle installed in the vacuum chamber, electrons collide with the evaporated vapor to ionize the vapor, and the vapor is accelerated by an electric field and deposited on the substrate, the current density of the ions flying around the substrate and the center of the substrate are The electric field distribution on the substrate is adjusted by detecting the current density of the ions flying to the substrate with a current detector, and varying the potential of multiple substrate bias electrodes installed in the substrate holder based on the detected current value. , which attempts to control the current density distribution of ions reaching the substrate.

Further, the ion beam film forming apparatus according to the present invention is an ion beam film forming apparatus for depositing a vapor deposition material on the surface of a substrate, and includes a substrate holder for holding a substrate, and a plurality of substrates installed in the substrate holder. a bias electrode;
A current detector for ions flying to the periphery of the substrate, a current detector for ions flying to the center of the substrate, and the potential of multiple substrate bias electrodes installed in the substrate holder based on the signals from each current detector. a crucible storing a vapor deposition material, heating means for the vapor deposition material in the crucible, and a nozzle provided in the crucible for spouting evaporated vapor of the vapor deposition material into a vacuum chamber; Equipped with means for ionizing and accelerating evaporated vapor provided between the crucible and the substrate, the electric field distribution on the substrate can be controlled by adjusting the potential of a plurality of substrate bias electrodes installed in the substrate holder. It is something.

[0017]

[Actions] The effects obtained by the above-described structure or means are as follows.

[0018] The vapor deposition material in the crucible is heated by the heating means to evaporate the vapor deposition material, thereby increasing the pressure of the vapor of the vapor deposition material inside the crucible. When the evaporated vapor of the deposition material is ejected from the nozzle provided on the upper surface of the crucible, the internal pressure of the crucible container (e.g., 10-1 to several Torr) and the pressure outside the container (e.g., 10-6 to 10-8 Torr) are mixed. The pressure difference causes adiabatic expansion and supercooling. As a result, the vapor condenses and an evaporated vapor stream (cluster beam stream) is formed.

After this, an electron emitting means consisting of an ionizing thermionic emitting filament, a thermionic extraction grid, and a thermionic extraction power supply device is used to shower the cluster beam with electrons, and the constituent atoms of the cluster are A beam of cluster ions is formed by ionizing one of the atoms. At this time, a cluster beam ionized to a maximum of about 50% can be formed. Next, the cluster ions are accelerated by the electric field formed by the accelerating electrode, causing them to collide with the substrate, and the neutral clusters that have not been ionized are collided with the substrate at the velocity of the crucible nozzle jetting, so that the evaporated material is deposited on the substrate. Forms a thin film.

The current density of ions flying to the periphery of the substrate and the current density of ions flying to the center of the substrate are detected by current detectors, and based on the detected current values, a plurality of substrate bias voltages installed in the substrate holder are detected. The electric field distribution on the substrate is adjusted by varying the potential of the electrode, that is, by setting the potential of the substrate to be negative with respect to the ground potential and the absolute value of the potential at the periphery of the substrate to be larger than that at the center of the substrate. It becomes possible to do so. This makes it possible to control the current density of ions flying to the periphery of the substrate and the center of the substrate, so that the amount of ions reaching the deposition surface of the substrate is uniform and It becomes possible to significantly increase the size.

[0021] Furthermore, if the potential of the substrate holder is biased to a high negative potential with respect to the ground potential, it is possible to accelerate the cluster more than when accelerating the cluster using only the accelerating electrode. It goes without saying that the kinetic energy of the cluster can be significantly increased.

As described above, by measuring the ion current distribution reaching the substrate and adjusting the electric field distribution on the substrate based on the detected current value, and by expanding the control range of the kinetic energy of the ions, It becomes possible to precisely control ions over a wide range, and film quality (film crystallinity, crystal structure, orientation, etc.) can be controlled in the film thickness direction.

[0023] As a result, it becomes easy to artificially control the film quality of the formed film, and it is possible to create a material with properties not previously available.

Therefore, according to the above means, the amount of ions reaching the substrate can be greatly increased and the controllability can be improved, so that a high-quality thin film can be obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view of a main part showing the structure of an embodiment of the cluster ion beam film forming apparatus of the present invention. The cluster beam generating section has the same configuration as the conventional example. Reference numeral 20 denotes a crucible (Knudsen cell) having a single layer structure made of carbon and having a nozzle 21 with a diameter of about 1 mm formed on the upper surface. The vapor deposition substance 22 is heated by a resistance heating type heater 23 installed on the outer periphery of the crucible 20 as a heating means. 24
is a crucible heating power source for applying voltage to the resistance heating type heater 23 to heat it.

The ionization means for the cluster beam is a thermoelectron-emitting filament 25 for ionization and a tantalum mesh placed inside the thermionic-emitting filament for ionization so as to surround the flow path of the cluster beam, which is formed into a cylindrical cage shape. It consists of an electronic drawer grid 26.

Reference numeral 27 denotes a power supply for heating the ionizing thermionic emission filament 25 for applying a voltage to the thermionic emission filament 25 for ionization, and 28 a power source for applying a voltage between the grid 26 and the thermionic emission filament 25 for ionization. Thermionic emission filament 2 for ionization heated to high temperature
5, a thermionic extraction power supply device for extracting thermionic electrons from the grid 26; 29 is a heat shield disposed to enclose the ionizing thermionic emission filament 25;

Reference numeral 30 denotes an acceleration electrode as means for accelerating the ionized cluster, and an acceleration power supply device 31 applies a voltage between it and the grid 26 for extracting electrons in the ionization section. In this embodiment, the potential of the accelerating electrode 30 is the ground potential. A cluster ion beam accelerated by the electric field generated by the accelerating electrode 30 collides with the substrate 32 to deposit a thin film. In this example, an electrically insulating disk-shaped glass substrate was used as the substrate 32. The substrate 32 is fixed to an insulating substrate holder 35 with an insulating disk 34 sandwiched therebetween using a conductive ring-shaped substrate holder 32.

The substrate holder 35 includes a disk-shaped substrate bias electrode 36 in its center and a ring-shaped substrate bias electrode 37 in its periphery. Reference numerals 38 and 39 set the potentials of the substrate bias electrode 36 at the center and the substrate bias electrode 37 at the periphery in the substrate holder 35 to a negative potential with respect to the ground potential, and also to the potential of the substrate bias electrode 37 at the periphery. This is a variable DC power supply device for setting the absolute value larger than that of the substrate bias electrode 36 in the center.

During film formation, the current value of the ions flying to the periphery of the substrate is detected by using the current detector 40 that flows into the conductive ring-shaped substrate holder 33. Further, the current value of the ions flying into the center of the substrate is determined by installing a Faraday cup 41 at the bottom of the center of the substrate, and detecting the current flowing into the Faraday cup 41 using a current detector 42.

Based on this detected value, the variable DC power supply device 3
8 and 39, by varying the potential of a plurality of substrate bias electrodes 36 and 37 installed in the substrate holder to adjust the electric field distribution on the substrate, the ion density reaching the surface of the substrate 32 can be precisely controlled. Take control. Note that the Faraday cup 41 is movable and moves to a position where it does not interfere with the film formation on the substrate 32 during film formation.

The cluster ion beam film forming process using the cluster ion beam film forming apparatus of this embodiment is as follows.

The vapor deposition material 22 in the crucible 20 is heated by the resistance heater 23 to evaporate the vapor deposition material 22, and the pressure of the evaporated vapor 43 of the vapor deposition material 22 in the crucible 20 is set to about 1 Torr. When the evaporated vapor 43 of the vapor deposition substance 22 generated inside the crucible 20 is ejected from the nozzle 21 provided on the upper surface of the crucible 20, the pressure inside the crucible 20 container (1T
The evaporated steam 43 is adiabatically expanded and supercooled due to the pressure difference between the pressure outside the container (set at 10-6 Torr) and the pressure outside the container (set at 10-6 Torr). Therefore, the vapor condenses and a cluster beam flow is formed.

After that, in the ionization section, the grid 2
A beam of cluster ions in which one atom among the constituent atoms of the cluster is ionized by showering the cluster beam passing through the center of the grid 26 with electrons drawn from the ionizing thermionic emission filament 25 to the inside of the grid 26. form. Then, the cluster ions are accelerated by the electric field formed by the accelerating electrode 30 and collided with the substrate 32 to form a thin film of the vapor deposited substance 22 on the substrate 32 .

According to this embodiment, the potential of the substrate 32 is set to be a negative potential with respect to the ground potential, and the absolute value of the potential of the peripheral portion of the substrate is set to be larger than that of the central portion of the substrate (for example,
Substrate bias electrode 36 in the center of the substrate holder 35
The potential of -1000V is applied to the substrate bias electrode 3 at the periphery.
7), the electric field distribution on the substrate can be adjusted, and the current density of ions flying to the periphery of the substrate and the center of the substrate can be controlled. It becomes possible to uniformly and significantly increase the amount of ions reaching the substrate deposition surface regardless of the voltage value.

Furthermore, by biasing the potential of the substrate holder to a negative high potential with respect to the ground potential, it is possible to accelerate the clusters even more than when accelerating the clusters using only the accelerating electrode 30. The kinetic energy of the clusters when they collide can be significantly increased. Furthermore, even if the substrate 32 is a semiconductor or an insulator, or even if vapor reaches only within the substrate, the ionic current can be measured using the Faraday cup 41, making it possible to control the film quality with high precision. .

Furthermore, in the conventional example, when the substrate potential was ground, the current value measured on the evaporation surface of the substrate 32 could become negative depending on the film forming conditions, but with the configuration of this embodiment, For example, the current value of ions reaching the deposition surface of the substrate 32 can be maintained at a positive value with good controllability. Note that when the potential of the substrate holder is made positive with respect to the ground potential, the current value reaching the vapor deposition surface of the substrate 32 becomes a negative value, and ions no longer reach the substrate vapor deposition surface.

Therefore, by measuring the ion current distribution reaching the substrate and adjusting the electric field distribution on the substrate based on this detected current value, and by expanding the control range of the kinetic energy of the ions, it is possible to It becomes possible to precisely control the amount of ions that arrive over a wide range, and the film quality (film crystallinity, crystal structure, orientation, etc.) can be controlled in the film thickness direction. As a result, it becomes easy to artificially control the film quality of the formed film, and it is possible to create a material with properties that have not been previously available.

As described above, according to the present invention, the amount of ions reaching the substrate can be greatly increased and the controllability can be improved, so that a material having high quality and highly functional properties can be formed into a film. It becomes possible to do things.

FIG. 2 is a sectional view of a main part showing the structure of another embodiment of the cluster ion beam film forming apparatus of the present invention. The parts other than the cluster beam generation part and the reactive gas introduction part are the same as the embodiment shown in FIG. In FIG. 2, parts with the same functions as those in FIG. 1 are given the same numbers.

The cluster beam generating section will be explained. The cluster beam generation part is a nozzle 2 with a diameter of about 1 mm.
A crucible (Knudsen cell) 20 having a single-layer structure made of carbon with 1 formed on the upper surface of the crucible, and a spiral electron bombardment for heating the crucible 20 installed on the side of the crucible 20 in parallel to the cylindrical surface of the crucible 20. Thermionic emission filament (
(hereinafter referred to as an electronic bombardment filament) 44. 45 is filament 44 for electronic bombardment
A power source 46 for heating the electron bombardment filament 46 applies a voltage between the crucible 20 and the electron bombardment filament 44 to draw thermoelectrons from the electron bombardment filament 44 heated to a high temperature; By colliding the thermoelectrons with the crucible 20, the crucible 2
This is a crucible heating power supply for electronic bombardment heating of 0.

In this embodiment, the crucible 20 and the grid 26 for extracting thermionic electrons constituting the ionization section are set to earth potential. Further, in this embodiment, the electrical potential of the conductive ring-shaped substrate holder 33 is set to be the same potential as that of the ring-shaped substrate bias electrode 37 provided at the peripheral portion within the substrate holder 35.

Next, the reactive gas introduction section will be explained. Reactive gases such as elements constituting a compound, such as oxygen, hydrogen, and nitrogen, are supplied from a gas cylinder 47 to a flow rate control valve 4.
After the flow rate is adjusted in step 8, it is introduced into the vacuum chamber 49 near the substrate 32.

The cluster ion beam film forming process using the cluster ion beam film forming apparatus of this embodiment is as follows.

The vapor deposition material 22 in the crucible 20 is heated by electron bombardment to evaporate the vapor deposition material 22, and the pressure of the evaporated vapor 43 of the vapor deposition material 22 inside the crucible is increased. When the evaporated vapor 43 of the vapor deposition material 22 generated inside the crucible is ejected from the nozzle 21 provided on the upper surface of the crucible 20, it expands adiabatically.
Supercooled. This causes the vapor to condense and form a cluster beam stream. The reactive gas introduced into the vacuum chamber 49 diffuses within the vacuum chamber 49, and reactive gas atoms also diffuse into the ionization section.

In the ionization section, the cluster beam of the evaporated vapor 43 and the reactive gas atoms are showered with electrons extracted from the thermionic emission filament 25 for ionization into the grid by the thermionic extraction power supply 28, thereby forming the cluster beam and the reactive gas atoms. Ionizes reactive gases. Then, the cluster ions and reactive gas ions are accelerated by the electric field formed by the accelerating electrode 30 and collided with the substrate 32 to form a compound thin film of the vapor deposited substance 22 on the substrate 32 .

According to the above means, the amount of reactive gas ions formed can be controlled by controlling the flow rate of the reactive gas introduced into the vacuum chamber. Therefore, since the reactive gas ions can be added to the cluster ions, the current value of the ions reaching the substrate 32 is significantly increased. Furthermore, as in the previous embodiment, the distribution and flow rate of ions reaching the substrate can be controlled by measuring the ion current distribution reaching the substrate and adjusting the electric field distribution on the substrate based on this detected current value. Therefore, it is possible to expand the control range and more precisely control the amount of ions that reach the substrate, and it is possible to form a film of a material having high quality and highly functional characteristics.

[0048]

As described above, according to the present invention, it is possible not only to improve the controllability of ions reaching the substrate and to greatly increase the value of the ion current, but also to reduce the kinetic energy of the cluster ion beam. It is possible to realize a method and an apparatus for forming a thin film material having high quality and highly functional properties.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an ion beam film forming apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of another embodiment of the present invention.

FIG. 3 is a sectional view of a main part of a conventional ion beam film forming apparatus.

[Explanation of symbols]

20 Crucible 21 Nozzle 22 Vapor deposition substance 23 Resistance heating heater 25 Thermionic emission filament for ionization 26 Grid 30 Acceleration electrode 31 Acceleration power supply device 32 Substrate 35 Substrate holder 36, 37 Substrate bias electrode 38, 39 Variable DC power supply device 40, 42 Current detector 43 Evaporated vapor 44 Electronic bombardment filament 49 Vacuum chamber

Claims (3)

[Claims] Claim 1: The vapor deposition material in a crucible is heated to evaporate the vapor deposition material, and the vaporized vapor of the vapor deposition material is ejected from a nozzle provided in the crucible into a vacuum chamber, and the vaporized vapor is bombarded with electrons to create vapor. When ionizing and accelerating it with an electric field and depositing it on the substrate, a current detector detects the current density of the ions flying to the periphery of the substrate and the current density of the ions flying to the center of the substrate, and the detected current value is An ion beam film forming method in which the electric field distribution on the substrate is adjusted by varying the potential of multiple substrate bias electrodes installed in the substrate holder, thereby controlling the current density distribution of ions reaching the substrate. 2. The ion beam film forming method according to claim 1, wherein the potential of the substrate is set to be a negative potential with respect to the ground potential, and the absolute value of the potential at the peripheral portion of the substrate is larger than that at the center portion of the substrate. 3. An ion beam film forming apparatus for depositing an evaporation substance on the surface of a substrate, comprising: a substrate holder for holding the substrate; a plurality of substrate bias electrodes installed in the substrate holder; a current detector for ions flying toward the center of the substrate; a variable power supply device, a crucible storing a vapor deposition material, a means for heating the vapor deposition material in the crucible, a nozzle provided in the crucible for spouting evaporated vapor of the vapor deposition material into a vacuum chamber, and a connection between the crucible and the substrate. An ion beam characterized by comprising means for ionizing evaporated vapor and accelerating means provided in between, and controlling the electric field distribution on the substrate by adjusting the potential of a plurality of substrate bias electrodes installed in a substrate holder. Film forming equipment.