HU200035B - Method for secondary treatment of dielectric thin layers - Google Patents

Abstract

The method according to the invention is particularly suitable for increasing the adhesion and mechanical strength of SiO2, S1O2 and / or T2O3 containing films, preferably on glass substrates, and for trimming optical properties. The dielectric thin films applied to the substrate are used as targets, and their surfaces are chemically inert to the thin film material, preferably from 7 to 15, especially nitrogen, oxygen and argon, with accelerated ions of 1.540-15 to 2-1 2- "" J, 64012 to 340M ion / cm 2. directly irradiated at a dose equal to the dose.

Description

FIELD OF THE INVENTION The present invention relates to a process for curing dielectric thin films, which increases the adhesion and mechanical strength of thin dielectric layers (e.g. SiO, S1O2, T12O3, etc.), and affects, trims, and optical properties. This method is very advantageous in the manufacture of, among other things, optical dielectric layers, where an important requirement is the good adhesion of the layers to the substrate and their resistance to mechanical stress. In many cases, it can be very useful to be able to modify its optical properties in a controlled manner as required.

Optical thin films are generally applied to a glass substrate by vacuum evaporation, cathode spraying, or other processes. The composition of the layers is most often SiO, SiO2 and T12O3, which are often applied in several successive steps to form a sandwich structure.

In integrated optics, there is known a method (GB 2,079,536) for creating a high resolution optical grid by implantation. Implantation, as an intermediate step in a multistep technology, is performed through a properly designed mask, so that the ion beam modifies the properties of the irradiated object in an inhomogeneous manner, varying from place to place. Among the changes caused by the ion beam are the reduction of the refractive index of the material and the increased sensitivity to chemical milling in the irradiated areas.

It is also known that ion beam irradiation of silicone glasses in integrated optics can be very effective in locally modifying the refractive index (P. D. Townsend, S. Velette, Ion Implantation / Treating on Materials Science and Technology, Vol. 18 / ed. J.

K. Hirvonen, New York: Academic). In the case of various materials used in electro-optics, such as lithium niobate, ion implantation can be used effectively to form active optical devices / D. T. Y. Wei, W. W. Lee,

L. R. Bloom, Appl Phys. Lett., 25, 329 (1974)]. An interesting application of ion implantation of optical materials is the so-called. implementation of image storage also / T. J. Magee, M. Lehmann, Application of Ion Beams to Materials. Inst. Phys. Conf. Ser. No. 28 ed. G. Carter, J.

S. Colligon and W. A. Grant (Bristol: Institute of Physics) /; / Fri S. Percy, C. E. Land, Nucl. Instrum. Methods, 209/210, 1167 (1983). However, a process for treating dielectric thin films has not yet been developed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for the post-treatment of dielectric thin films which enables the mechanical and optical properties of the thin films applied to the substrate to be improved.

The invention is based on the discovery that ionized, high-energy accelerated atoms or molecules gradually lose their energy as they enter the layer due to collision with the atoms of the layer, and that when properly selected, they are most inhibited at the carrier-layer transition. During this process, the microstructure of the boundary layer can be so favorably influenced that the adhesion and mechanical strength of the layer can be significantly increased. And the interaction between the dielectric layer and the irradiated particles may alter the optical properties.

In the process according to the invention, in a device designed for this purpose, the substrate dielectric is applied as a target and the surface of the substrate is chemically inert to one of the elements of the order of 7-20, in particular nitrogen, oxygen or argon ^. - directly irradiated with 2 · 10 ^-15 J accelerated ions at a dose of 6 · 10 ¹² - 3 · 10 ¹⁴ ions / cm ² . The accelerating voltage used, the irradiated dose and the type of ions used are experimentally selected to optimize the optical properties of the thin films due to the irradiation and to optimally improve their mechanical properties.

When selecting the ions to be used for irradiation, it is essential that no chemical reaction with the thin-film material is carried out. Nitrogen and noble gases, e.g. argon. Since the samples are mostly oxides, oxygen is not a foreign matter to the crystal lattice constituents, and its ions are also advantageous. The amount of oxygen introduced during implantation is so small that it does not significantly alter the stoichiometric balance.

Another aspect of ion selection is the size of the ions, as we have found that the mechanical action of the ions is predominant; the type of ion is of secondary importance. Elements 7-20 of the Periodic Table are best met by this condition.

In the most common thin films, both of these conditions are met and the ions of nitrogen, oxygen and argon are preferred.

To illustrate the procedure, experiments were performed on sandwich structures of SiO2, T12O3, S1O2, and T12O3 on glass substrates. To achieve the desired result, the thin film layer of the dielectric was radiated homogeneously with ions accelerated to 1.5-10 ^-15 to 2T0 ¹⁵ J at a dose of 6Ί0 ¹² to 3Ί0 ¹⁴ ions / cm ² .

HU 200035 Β

We achieved particularly good results with the following parameters:

the. ) S1O2 thin film irradiation 1,710 ^-15

With J energy Ar 'ions at a dose of ^{3 to 10 14} ions / cm ² .

b. ) T12O3 thin film irradiation 1.9-10 ^-15

With J energy N * ions at a dose of 2.5-10 ¹⁴ ions / cm ² .

c. ) S1O2 + T2O3 thin film irradiation

With OMons of 1.9-10 ^-15 J energy,

^{At a} dose of 2.5-10 ¹⁴ ion / cm ² .

In the above cases, it was found that the initial adhesive strength of the layers, from 1000 to 1500 N / cm ^{2, was} so increased by irradiation that they could not be torn off the substrate, sometimes even with a tensile pressure of 3000 N / cm ² . Approximate measurements were also made on the microfine strength of the layers, which showed a 20-30% improvement in irradiation.

The dose range of 6 to 10 ¹² to 3 to 10 ¹⁴ ions / cm ² leaves the optical properties unchanged, since the ion beam in the layer itself does not cause significant destruction but significantly increases adhesion and hardness. We also measured that the radiation spectrum of the interference filters and laser mirrors changed as a result of the irradiation, the intensity of some peaks changed, its location shifted to other wavelengths, and in some cases its transmittance (while the other wavelengths did not change substantially) increase selectivity. These changes can be controlled within certain limits by selecting the irradiation parameters.

In summary, the present invention, when used as a final complementary step in optical thin film production technology, significantly improves the adhesion and technical properties of thin films and enables the optical properties to be trimmed.

Claims (1)

A process for curing dielectric thin films, enhancing adhesion and mechanical strength of thin films, mainly SiO, S1O2 and / or Ti2O3, preferably on a glass substrate, and trimming of optical properties, wherein the dielectric substrate is applied to the substrate, , preferably homologous to one of the elements of the order of 7-20, in particular nitrogen, oxygen or argon, accelerated to 1.5-10 ^-15 to 2-10 ^-15 J, in a dose of 6-10 ¹² to 3-10 ¹⁴ ions / cm ² , directly irradiated.