SU910843A1 - Cathode assembly - Google Patents

Description

one

The invention relates to the deposition of thin dielectric films by ion sputtering of the material in a vacuum.

A cathode assembly is known, preferably for ion-plasma deposition of dielectric films in vacuum, containing a target cathode, an anode.

However, in such devices, it is not possible to obtain thick layers of dielectrics with a thickness of more than 1 micron due to the pressing speed of the film, which is 0.3-1.0 micron / h. .

This disadvantage is partially eliminated in ion-plasma spraying devices, where the rate of deposition of the film is significantly higher.

The closest in technical essence is the cathode assembly, mainly for nozzle-plasma deposition of dielectric films in vacuum, containing a cathode, a myon, a schie, an anode, and a magnetic system. Such a cathode assembly allows to obtain high rates of deposition of a pl.enok and, therefore, significantly reduce the time to obtain thick layers 2.

However, thick dielectric layers of a perfect structure cannot be obtained due to the passivation of the anode,

10 caused by the growing dielectric film. The passivation of the metal cathode is absent due to the HIS11 sputtering speed — the dielectric film does not have time

15 is formed.

When the anode is passivated, the electron current increases to: a) grounded: substrate holder and sub-cap device parts. Under the influence of the electron current, a negative floating appears: the pigment on the passivated surfaces. Due to this, the glow discharge goes beyond the spray cell, the latter leads to a sharp increase in the desorption of contaminants from the surface of the subcollege device. HI molecules (,. CO, O (etc., the film formed on the substrate) are subject to reactive gaseous contaminants. At the same time, when the plasma is drawn into the volume of the subcollet device, the substrate is in the discharge zone. additionally, uncontrolled heating of the substrate surface to ISO-ZSO C. Both of these factors significantly reduce the quality of the crystalline structure of the growing dielectric film. During the spraying process, dielectric film breakdown may occur Anode at the anode. Such breakdowns lead to instability of the discharge. With an increase in the dielectric thickness at the anode, the discharge gradually fades out and can go out completely. All this leads to a controlled decrease in the rate of crushing during operation. Finally, during film deposition it is affected by the floating potential induced by the plasma. The floating potential can reach 100–300 V, depending on the applied cathode potential and the geometry of the device. This accumulated discharge flows from the surface to cause the destruction of the sweat of the film, the last. It should be noted that these negative phenomena are most pronounced when applying films of dielectrics with a thickness of more than 2-3 microns, i.e. when passivation of the anode is most pronounced. The purpose of the invention is to improve the quality of dielectric films. This goal is achieved by the fact that the cathode assembly, mainly for ion-plasma deposition of dielectric films in vacuum, comprising a cathode, a target, an anode, a magnetic system, is provided with a heater located on the side of the anode opposite to the working surface of the cathode. ... The drawing shows the proposed cathode assembly. 3 .4 The device consists of a vacuum chamber 1 with nozzles 2 and 3 for the inlet of the working gas and pumping, cathode 4, magnetic system 5, target 6 of sprayed material, annular anode 7, heater 8 and substrate Hold1 9 on which substrate 10 is installed The cathode 4 is isolated from the grounded chamber 1 by means of dielectric spacers. A constant voltage to the cathode 4 and and the anode 7 is supplied from the power source 11 to the heater 8 from the power source 12. The device includes a radiation protection screen 13. The device works as follows. Through pipe B, the vacuum chamber 1 is pumped to pressure 10 and then, after heating the anode 7 and substrate holder 9 to the set temperatures, working gas mixture, such as argon masks, is fed into chamber 1 to the required pressure. Temperature: the heating of the anode 7 is maintained at such a level that the specific resistance of the dielectric film covering the anode is so small that it allows for the necessary conductivity. Passivation is absent, and the entire electron current is captured by the anode. For most dielectrics, the anode temperature must be maintained in the ZOO-UOO C range depending on the conductivity of the dielectric film, a negative potential is applied to the cathode, and a discharge is ignited in chamber 1. The working gas ions bombard and spray the metal target 6. Spray material chemical reaction products and the working gas, deposited on the substrate, forms a dielectric layer. The test of the proposed device for applying dielectric layers is carried out by sputtering an aluminum nitride film (S 10 ° - OM-CMJ. An aluminum disk is used as a target (A 995J, and an argon-ammonia mixture is used as a working gas. Ammonia content in the mixture varies in within 1–100% with a total pressure of Co, 6–5). The anode in the form of a ring of tantalum sheets is heated to. Infrared lamps are used as a heater. The half-burner temperature is in the range of 300–1200 ° C. one 50 V to 5-10 V when the anode is heated to the operating temperature. At the same time, almost all the electron current is absorbed by the anode. The discharge is localized in the anode-target space and has stable parameters. There are no film breakdowns deposited on the anode. different times during the sputtering process give the same results (with an accuracy of 10%). The heating of the substrate under the influence of the discharge decreases from 200 to (without a heater.

The growth rate of the A1N films varies from 1 to 20 µm / h, depending on the pressure of ammonia in the gas mixture and the power of the discharge. It was possible to obtain films with a thickness of up to 15–20 µm with a specific resistance of 10. Ohm-cm and a dielectric loss tangent of 0.01. Based on aluminum nitride films, film piezo transducers were manufactured. Losses on one transformation at a frequency of 500 MHz

are 10-dB, and at 1 GHz, 12 dB. Such loss values indicate the possibility of creating efficient piezo transducers based on aluminum nitride films. Thus, this cathode assembly provides higher quality dielectric layers.

Claims (2)

1. US Patent 3962062, cl. 204-192, 1976 .. 2. US patent number 3528902, cl. 204-192, 1970 (prototype).