JPS589981A - Vacuum deposition device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum evaporation apparatus used particularly in evaporation techniques that utilize the properties of plasma.

In the vapor deposition technology that utilizes the properties of plasma, there is a known device that uses hollow cathode arc discharge plasma to evaporate and ionize the material. In the latter case, the plasma rays exiting from the cathode are redirected by a magnetic field perpendicular to the rays. It will be done. The maximum value of the power (PA) applied to the anode surface is 50 degrees of the total power in devices known from the literature.

The basic idea of the device known from the literature is that the gas inside the evacuated exhaust bell flows through a small tube of suitable dimensions and made of a material with a high melting point, which is cooled at one end. be.

By applying a sufficiently high voltage between the small tube connected as a cathode and the anode, a glow discharge is generated between these two electrodes. If the current is selected to be sufficiently large, the uncooled end of the cathode is heated, thermal radiation of electrons is discontinued and the glow discharge transforms into a so-called hollow cathode arc discharge. A part of the total energy PB:tJB formed by the electric discharge current (IB) and electric discharge pressure (UB) in the plasma of the hollow cathode electric arc discharge is given to the anode and is present in the anode crucible. Used for evaporation of materials.

In addition to the relatively low energy utilization rate mentioned above,
The devices known so far have the following drawbacks. This has the disadvantage, particularly when the cathode is arranged above the anode, that the cathode is unavoidably influenced or contaminated by the action of the material evaporated from the crucible or the active gas. Furthermore, no device is known heretofore which makes it possible to continuously define the diameter of the melting surface of the contents of the crucible. - The operation of the previously known device, after evacuation of the exhaust bell, takes place approximately through the following four steps:

1. Set a high gas charging rate, 2. Glow discharge with a large current between the cathode and anode (5
A high voltage (1 to 2 KV) is applied via an additional network device to provide the necessary high discharge voltage (3 to 10 A), and a device for maintaining the electric arc is connected ( Ue70V
,■=100-200A), 4. After the hollow cathode arc discharge is started, reduce the gas charging rate to the predetermined value.

As mentioned above, the drawbacks of the prior art and the need for special shielding and isolation to prevent the transition of the glow discharge into a thermoelectric arc is that the plasma rays of the hollow cathode arc discharge are This is thought to be because the equipment used for evaporation and vapor deposition of is not yet in use industrially.

The aim of the invention is to develop an evaporation source which can be used universally for evaporation using the properties of plasma and which does not have the disadvantages of known devices.

The object of the invention is to make it possible to continuously adjust the diameter of the melting surface by optimizing the arrangement of the anode/cathode and the guidance of the plasma radiation, with a low energy efficiency (at least The purpose of the present invention is to create an easily operated device that is improved to 80 cm.By preventing the evaporation of the cathode and its consumption by the reacting gases, the lifetime of the cathode is increased by at least 50%. The cost of electricity supply equipment shall not be increased.

The above problems are solved by the present invention as follows. That is, a hollow cathode, known per se, is placed laterally at a distance from a water-cooled evaporation crucible and is directed towards the surface of the contents of the crucible by a magnetic field generated and orthogonal to the hollow cathode when it is actuated. Plasma radiation is 7 to 2oCr
The space above the hollow cathode has a diameter of 8 to 20 m to allow the plasma rays to penetrate.
The evaporation crucible, connected as an anode, is fixed on the substrate of the evaporator via an insulating block and is bounded by a cover chamber with an opening of diameter 7H and continuously regulates the diameter of the melting surface. forming a longitudinal magnetic field for,
The solution is to surround the coil in the form of an iron-shielded lens.

A coil forming a longitudinal magnetic field, electrically insulated from the crucible, is located at the inner diameter of its iron shield, at the level of the surface of the melt, and a slit along the circumference The crucible-coil system is completely surrounded by one container up to the upper opening of the crucible and is connected to the substrate by an easily releasable connecting element. is fixed. A coil generating a magnetic field perpendicular to the cathode is arranged, which coil is protected from the action of the plasma by a cover plate. On either side of the coils, which create orthogonal magnetic fields, weakly magnetic plates are placed in the container to help redirect the plasma beam.

The operation of the device of the invention is carried out according to the following steps.

1. Setting the planned value of gas charging rate, 2. Heating the cathode; 6. Connection of voltage to maintain electric arc.

After setting the gas pressure or gas charge rate, the hollow cathode is heated to the required cathode temperature. When the cathode reaches its temperature and emits electrons, these electrons can ionize the discharge body due to the applied voltage. The ionization process can be monitored by an ammeter placed in the circuit of the auxiliary anode. In this case, an exhaust bell is used as an auxiliary anode, and anode power is applied to the exhaust bell via a 5 ohm resistor.

The discharge becomes stable with a discharge current of approximately 10 amperes.

The voltage of the limiting resistor changes the voltage state of the evaporator, so that a portion of the discharge stream is admitted to the crucible anode. At this time, a decrease in current is observed with an ammeter. This decrease in current indicates stable operation of the evaporator. The auxiliary anode is then disconnected from the crucible anode and the desired evaporator output is set.

The invention will be explained in more detail by way of example in the following description. The accompanying drawing shows a longitudinal section through the device according to the invention. The device consists essentially of four parts: a cathode arrangement 1, a crucible anode 2, a coil 6 for forming an orthogonal magnetic field with a directional plate 4, and a coil 5 for forming a longitudinal magnetic field. be. The distance from the crucible anode 2 to the laterally located cathode arrangement 1 is chosen such that the length of the plasma ray is 10 cm.

A crucible anode 2 with a connecting conductor 6 is fixed via an insulating block to an evaporator substrate 8, which is held on an exhaust bell 9 by means of a cathode arrangement 1. Above cathode arrangement 1,
A cover chamber 10 with an opening 11 is arranged, which opening preferably has a diameter of 15 mm. Container 12 surrounds and protects the device of the invention from all sides.

The cover plate 15 also protects the coil 3, which forms orthogonal magnetic fields, from the action of plasma radiation. The devices connecting these parts to each other are designed as easily releasable bayonet or screw connections, thus allowing quick and simple assembly and disassembly.

The slits 14 provided on the inside of the iron shielding of the coils 5 which form the longitudinal magnetic field ensure that continuous melting is achieved even if the surface height of the melt in the crucible decreases during charging. It is arranged in such a way that it does not affect the regulation of the surface diameter. However, the width of this slit must not be wider than 4 to 10 mm, depending on the diameter of the crucible. However, it is also possible to continuously replenish the crucible via replenishing or dosing devices which are known per se.

The device according to the invention has a few important technical and economical features compared to the state of the art known up to now, so that it is particularly promising for use in plasma-based vapor deposition.

By arranging the distance from the cathode to the anode to be spatially short and by specifically limiting the length of the plasma ray to 10 crIL, the energy utilization factor was increased by a factor of about 80. The placement of the cover chamber above the cathode creates a high pressure inside this chamber which, in conjunction with the 15 mm diameter opening, significantly prevents the ingress of gas from the exhaust bell. The cathode is thus not corroded when carrying out the reactive process. This is because the oxidation, carburization, and nitration caused by the introduced reacting gases are avoided and the lifetime of the cathode is significantly increased.

Since the exit opening for the plasma radiation from the cathode is below the surface of the melt in the crucible, fouling of the cathode is avoided and at the same time the material in the crucible is also prevented from becoming contaminated with particles of the evaporated cathode. ``It is impossible to perform a vapor deposition with shading on the surface of the underlying material. This is because the space above the crucible is free space for the material to evaporate.

A special form of coil for forming a longitudinal magnetic field housed in an iron container and the dense magnetic field generated by it and adjustable in strength guides and bundles the plasma rays and improves the evaporation rate. Needless to say, it is useful for adjusting the

[Brief explanation of drawings]

The accompanying drawing shows a longitudinal section through the device according to the invention. In the figure, 2... Crucible, 5... Coil □ that forms a longitudinal magnetic field, 9... Exhaust bell, 10... Cover chamber, 11... Opening , 14... slit.

Claims (1)

[Claims] 1) In a vacuum evaporation apparatus using a hollow cathode, a water-cooled copper crucible, and a magnetic field perpendicular to the plasma ray, the hollow cathode is disposed laterally at a distance from the copper crucible, The plasma ray generated when the hollow cathode is activated and directed onto the surface of the crucible contents has a length of 7 to 20 cm; the space above the hollow cathode has a diameter of is bounded by a wandering chamber α■ with an aperture aυ of 8 to 20 mm and the copper crucible (2) is fitted with a coil (5) in the form of an iron-shielded lens to form a longitudinal magnetic field. ) is surrounded by a vacuum evaporation device. 2) The current coil (5) forming the longitudinal magnetic field has a slit αxn of at least 111XI and at most 10mm wide to focus the plasma rays at the inner diameter of its iron shield. A device according to claim 1, characterized in that it comprises: 5) characterized in that, for the start of operation, the exhaust bell (9) is connected to the anode voltage via a 5 ohm resistor and that a notification device is arranged in this interruptible circuit to indicate that a discharge is taking place. Claim 1 or 2
Apparatus described in section.