JPH04221065A - Thin film forming device - Google Patents

Abstract

PURPOSE:To prevent the vaporized substance from being vapor-deposited on both the part except the vapor deposition part of the material to be vapor- deposited and a counter electrode holding the material to be vapor-deposited and furthermore to prevent plasma from being made unstable even when electric potential between the counter electrode and a grid is fluctuated. CONSTITUTION:A vaporization source 4 for vaporizing the vapor deposition substance is arranged in a vacuum tank 51. Both a grid 8 for passing the vaporized substance and a counter electrode 12 for holding a base plate 13 used as the material to be vapor-deposited are arranged oppositely to this vaporization source 4. A cylindrical magnet 19 is arranged which surrounds the space between the grid 8 and the counter electrode 12.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming thin films by plasma deposition.

0002

[Prior Art] Conventionally, with thin film forming apparatuses that form thin films by vapor deposition on the surface of substrates, etc., the adhesion of the formed thin film to the substrate is poor, and it is difficult to form thin films on substrates that are not heat resistant. There was a problem. Therefore, as in the thin film forming apparatus shown in Japanese Patent Publication No. 1-53351, an active gas, an inert gas, or a mixture thereof is introduced into a vacuum chamber, and plasma is generated using a DC power supply. This improves the adhesion of the thin film to the substrate. Furthermore, since this thin film forming apparatus can perform the plasma process at low temperatures, thin films can be formed on substrates such as plastics with low heat resistance.

0003

[Problems to be Solved by the Invention] However, in the thin film forming apparatus disclosed in Japanese Patent Publication No. 1-53351, plasma is generated in a vacuum chamber even in a space where plasma generation is not necessary, so that the deposited material is This results in so-called back-turning in which the film adheres to the back surface of the substrate. Furthermore, sputtering phenomenon etc. will occur on the surface of the vapor deposited layer of the substrate. Additionally, if the deposition material is an insulator or semiconductor, the deposition material will be deposited on the surface of the substrate or the counter electrode that holds the substrate, which will cause the potential between the grid, substrate, and counter electrode to fluctuate, causing plasma becomes unstable. Further, since the filament for generating thermionic electrons is installed so as to block the path connecting the evaporation source to the grid and the counter electrode, the filament constituent material generated from the filament will adhere to the substrate. The present invention has been made by focusing on the above-mentioned conventional problems, and can prevent the so-called back side in which the vapor deposition substance adheres to the back surface of the substrate, as well as the occurrence of sputtering phenomena etc. on the surface of the vapor deposited layer of the substrate. In addition, when the deposition material is an insulator or a semiconductor, the deposition material is not deposited on the surface of the substrate or the counter electrode that holds the substrate.
It is an object of the present invention to provide a thin film forming device that can prevent plasma from becoming unstable due to fluctuations in potential between a grid, a substrate, and a counter electrode, and prevent filament constituent substances generated from a filament from adhering to a substrate. purpose.

0004

[Means for Solving the Problems] The invention according to claim 1 provides a vacuum chamber into which an active gas, an inert gas, or a mixed gas of an active gas and an inert gas is introduced, and a vapor deposition substance is evaporated in the vacuum chamber. an evaporation source, an evaporation source power source that sets the evaporation source to a predetermined potential, and a counter electrode that holds a material to be evaporated, which is placed in the vacuum chamber and on which a evaporation substance is evaporated, in a position facing the evaporation source; a power source for a counter electrode that makes the counter electrode have the same potential as the evaporation source; a grid that is disposed between the evaporation source and the counter electrode and allows the vapor deposition material evaporated by the evaporation source to pass through; an electric field control means that has a positive potential with respect to the potentials of the counter electrode and the evaporation source, and that creates an electric field directed from the grid toward the material to be evaporated held by the counter electrode in opposite directions; and a filament for generating thermionic electrons arranged to ionize the deposition material evaporated by the evaporation source, characterized in that a magnet is arranged to surround the space between the grid and the counter electrode. This is a thin film forming device.

[0005] The invention according to claim 2 is the invention according to claim 1, wherein the filament does not block the passage path of the evaporated deposition material,
Moreover, the thin film forming apparatus is characterized in that the thin film forming apparatus is disposed so that the evaporation material evaporated by the evaporation source and the thermoelectrons generated from the filament collide approximately midway between the evaporation source and the grid. The invention according to claim 3 is the method according to claim 1, wherein an electron reflecting means having a potential lower than the potential of the grid and higher than the kinetic energy of the thermoelectrons generated from the filament is provided at a position opposite to the filament for generating thermoelectrons. This is a thin film forming apparatus characterized by the following.

[0006]

[Operation] In the present invention, an active gas, an inert gas, or a mixed gas of an active gas and an inert gas is introduced into a vacuum chamber, and the evaporation source is brought to a predetermined potential by a power source for the evaporation source.
A deposition material is evaporated by an evaporation source within the vacuum chamber. In addition, the counter electrode that holds the material to be evaporated in a position facing the evaporation source is brought to the same potential as the evaporation source by the counter electrode power supply, and the grid is brought to a positive potential with respect to the potential of the counter electrode and the evaporation source by the electric field control means. Moreover, the electric fields directed from the grid toward the material to be deposited held by the counter electrode are formed in opposite directions. Also, thermoelectrons are generated from the filament,
The evaporation material evaporated by the evaporation source is ionized, and the evaporation material evaporated by the evaporation source passes through the grid and is accelerated. The magnet forms a parallel magnetic field in the space between the grid and the counter electrode, and the parallel magnetic field accelerates the weakly diamagnetic plasma in the direction of the magnetic field. Therefore, even if the deposited material is an insulator or semiconductor and the deposited material adheres to the counter electrode and the positive potential between the grid and the counter electrode becomes unstable, the plasma will still move toward the material to be deposited. becomes possible. According to the third aspect of the invention, if the thermoelectron reflecting means is provided, the thermoelectrons generated from the filament are reflected by the thermoelectron reflecting means,
The reflected electrons and the hot electrons generated from the filament are not captured by the grid, which has a positive potential, but are pulled back by the Coulomb force of the grid and the parallel magnetic field of the magnet, and pass through the grid again. In other words, thermoelectrons repeat vibrational motion. Since the thermoelectrons are eventually absorbed by the grid, they do not reach the material to be evaporated, and the material to be evaporated is not subjected to electron bombardment. Therefore, the material to be deposited is not heated.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the figure, reference numeral 1 denotes a base plate, on which a bell jar 2 is attached via a packing 21, and a vacuum chamber 51 is formed. A hole 1A is formed in the center of the base plate 1,
A vacuum evacuation device (not shown) is connected to this hole 1A. The air inside the vacuum chamber 51 is exhausted by this evacuation device, and the inside of the vacuum chamber 51 is brought into a reduced pressure state. Further, a gas supply device (not shown) is connected to the vacuum chamber 51.
An active gas, an inert gas, and a mixed gas thereof can be introduced into the chamber 1 .

[0008] The base plate 1 is provided with a pair of electrodes 3a and 3b which also serve as supports, a pair of electrodes 5a and 5b, an electrode 7, an electrode 11, an electrode 30, and an electrode 31. Electrode 3
a, 3b, 5a, 5b, 7, 11, 30, and 31 are inserted into through holes formed in the base plate 1 and attached.

Conductive evaporation source supports 40 and 42 are attached to the electrodes 3a and 3b. A resistance heating type evaporation source 4 made of metal such as tungsten or molybdenum and formed into a coil shape is provided across the evaporation source supports 40 and 42 . The shape of the evaporation source 4 may be a coil shape or a boat shape, and in addition to a resistance heating type, an electron beam evaporation source or the like used in a conventional vacuum evaporation apparatus may be used.

Conductive filament supports 43, 44 are attached to the electrodes 5a, 5b. This filament 6 is arranged perpendicularly to the counter electrode 12. A filament 6 for generating thermoelectrons made of tungsten or the like is provided across the filament supports 43 and 44 . This filament 6 has a net shape. In addition to this, the filament 6 may have a lattice shape. A thermionic deflector electrode 17 is attached to the electrode 30 as a thermionic reflecting means. This thermionic deflector electrode 17 is arranged facing the filament 6.

A grid support 47 is attached to the electrode 7, and the grid 8 is supported on the grid support 47. The grid 8 has a mesh shape and is shaped to allow the evaporated substance to pass through. Electrode 11
A counter electrode support 61 having a tip bent at a right angle is attached to the counter electrode support 61, and the counter electrode 12 is supported at the tip of the counter electrode support 61. On the lower surface of this counter electrode 12,
A substrate 13 as a material to be evaporated is held by means not shown, and a counter electrode 12 is placed behind the substrate 13 when viewed from the evaporation source 4 side. A conductive support 20 is attached to the electrode 31, and a magnet 19 is fixed to this support 20. The magnet 19 has a cylindrical shape and surrounds a space connecting the evaporation source 4 and the counter electrode 12.

The pair of electrodes 3a and 3b are connected via an evaporation power source 14. The electrode 7 is connected to the positive terminal of the DC voltage power source 16, and the electrode 11 is connected to the negative terminal of the DC voltage power source 16. Electrodes 5a and 5b are connected to an AC voltage power source 15. Further, the electrode 30 is connected to an AC voltage power source 15 via a resistor 18. Note that a DC voltage power source may be used instead of the AC voltage power source 15. Electrode 31 is connected to AC voltage power source 22 . Note that the grounding shown in the figure does not necessarily have to be performed. Note that the above electrodes are connected to a power source via various switches for controlling the film forming process, but these are omitted from the diagram.

Next, the operation of the thin film forming apparatus 50 will be explained. The substrate 13 is held on the lower surface of the counter electrode 12. Further, the evaporation source 4 holds the evaporation material. The material to be deposited is determined by the thin film to be formed, but metals such as iron and nickel,
Metal oxides, nitrides, fluorides, sulfides and alloys are used. The inside of the vacuum chamber 51 is brought to a pressure ranging from 10 to the minus 3 power Pa to 10 to the minus 8 power Pa by the evacuation device connected to the hole 1a. Further, an inert gas such as argon is introduced by a gas supply device at a pressure of 10 Pa to 10 −3 Pa. Note that an active gas, an inert gas, or a mixed gas of an active gas and an inert gas may be used as necessary.

Next, power supplies 14, 15, 16, 18, 22
is activated, the grid 8 is brought to a positive potential, and the counter electrode 12 is brought to a negative potential. Further, a current is passed through the filament 6, and the filament 6 generates heat due to resistance heating and emits thermoelectrons. Argon molecules within the vacuum chamber 51 collide with thermionic electrons emitted from the filament 6. For this reason, the outer shell electrons of the argon molecule are ejected and ionized into positive ions. The evaporated material, that is, the particles of the evaporated material spread out and fly toward the substrate 13. Ionization of a portion of the evaporated substance and the argon gas is further promoted by collision with thermionic electrons emitted from the filament 6 and the aforementioned ionized argon gas.

Among the evaporated substances that have passed through the grid 8, those that have not yet been ionized are further ionized into positive ions by collision with the ionized argon gas between the grid 8 and the substrate 13, and evaporated. The ionization rate of the entire substance increases. The evaporated substance thus ionized into positive ions is accelerated toward the substrate 13 by the action of the electric field directed from the grid 8 toward the counter electrode 12, collides with the substrate 13 with high energy, and adheres thereto. Therefore, a thin film with very good adhesion is formed on the substrate 13.

On the other hand, a current is supplied to the magnet 19 from an AC power supply 22 through the support 20, and a parallel magnetic field is formed in the space between the grid 8 and the counter electrode 12. Confines plasma within space. The parallel magnetic field accelerates the weakly diamagnetic plasma in the direction of the magnetic field (toward the counter electrode 12). As a result, plasma, which was generated spatially and relatively randomly in conventional plasma deposition apparatuses, can be controlled to some extent by changing the strength of the magnetic field within a limited space. Furthermore, the angle of entry of the vapor deposition chamber into the substrate 13 can be made nearly vertical.

Furthermore, if the vapor deposited substance is an insulator or a semiconductor and the vapor deposited substance adheres to the counter electrode 12 and the positive potential between the grid 8 and the counter electrode 12 becomes unstable, the plasma may not reach the substrate 13. It becomes possible to move in the direction. Therefore, even when the electric field is unstable, the probability that the deposited material will reach the substrate 13 is improved. Furthermore, since the plasma is confined within the space surrounded by the magnets 19, the spatial stability of the plasma is improved.

A negative potential that is greater than the thermal kinetic energy of electrons and smaller than the absolute value of the positive potential of the grid 8 is applied to the thermionic deflector electrode 17 . Therefore, among the thermoelectrons generated from the filament 6, the thermoelectrons that did not contribute to the ionization of the vapor deposition material and the secondary electrons generated by the collision between the vapor deposition material and the thermoelectrons can be caused to collide with the vapor deposition material again. Therefore, the ionization efficiency of the vapor deposition material can be increased. Note that some of the thermoelectrons also contribute to the movement of electrons near the grid 8.

The reflected electrons and the thermoelectrons generated from the filament 6 are reflected by the thermionic deflector electrode 17 and have a positive potential, so they pass through without being captured by the grid 8, and the Coulomb force due to the grid 8 and
It is pulled back by the parallel magnetic field of magnet 19 and passes through the grid. That is, the thermoelectrons repeat oscillating motion around the grid 8. And finally, thermionic is grid 8
Since the electrons are absorbed by the electrons, they do not reach the substrate 13, and the substrate 13 is not subjected to electron impact. Therefore, the substrate 13 is not heated.

Since the filament 6 is arranged as described above, radiant heat from the filament 6 does not reach the substrate 13. Also, the constituent materials of the filament 6 are prevented from being deposited on the substrate. Furthermore, since the filament 6 is arranged perpendicular to the moving direction of the vapor deposition material, the flow of thermionic electrons and the flow of the vapor deposition material are perpendicular to each other. Therefore, collisions between thermal electrons and the vapor deposited material occur frequently.

[0021]

As described above, according to the present invention, it is possible to prevent the so-called back side where the vapor deposition substance adheres to the back surface of the material to be vapor-deposited, as well as the occurrence of sputtering phenomena on the surface of the vapor-deposited layer of the material to be vapor-deposited. become. In addition, when the deposition material is an insulator or a semiconductor, the deposition material is not deposited on the surface of the material to be deposited or the counter electrode that holds the material to be deposited, and the potential between the grid, the material to be deposited, and the counter electrode is This makes it possible to prevent the plasma from becoming unstable due to fluctuations in the plasma. Furthermore, filament constituent substances generated from the filament will not adhere to the material to be deposited.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a thin film forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

6 Filament 8 Grid 12 Counter electrode 13　　　　Substrate 19 Magnet 51 Vacuum chamber

Claims (3)

[Claims] Claims: 1. A vacuum chamber into which an active gas, an inert gas, or a mixed gas of an active gas and an inert gas is introduced; an evaporation source for evaporating a deposition material in the vacuum chamber; a power source for the evaporation source; a counter electrode that is placed in the vacuum chamber and holds the material to be evaporated on which the evaporation substance is deposited in a position facing the evaporation source; and the counter electrode is set at the same potential as the evaporation source. a power supply for a counter electrode, a grid disposed between the evaporation source and the counter electrode and capable of passing the evaporation material evaporated by the evaporation source; an electric field control means for forming a positive potential and an electric field directed from the grid toward the material to be evaporated held by the counter electrode in opposite directions; 1. A thin film forming apparatus comprising a filament for generating thermoelectrons for ionizing a substance, characterized in that a magnet is disposed to surround a space between the grid and the counter electrode. [Claim 2] In Claim 1, the filament does not obstruct the passage path of the evaporated deposition material and is generated from the evaporation material and the filament evaporated by the evaporation source approximately midway between the evaporation source and the grid. 1. A thin film forming apparatus characterized in that the device is arranged so that thermal electrons collide with each other. 3. In claim 1, an electron reflecting means having a potential lower than the potential of the grid and higher than the kinetic energy of the thermoelectrons generated from the filament is provided at a position opposite to the filament for generating thermoelectrons. Characteristic thin film forming equipment.