RU1535332C - Method of manufacturing elements of acoustic-wave-operated devices - Google Patents

Abstract

The invention relates to electronics. The aim of the invention is to increase the yield. A method of manufacturing elements of devices operating on acoustic waves includes forming, using a masking layer, a photoresist on the working surface of a sound duct 2 groups of strips of the first metal layer 3 by reverse photolithography, forming a dielectric layer 4 on top of it, additionally applying a layer of photoresist 5, exposing it from the side of the sound duct opposite to the working one, and developing, spraying the second metal layer, removing the second metal layer 6 with the layer otorezista. 9 ill. a E (L

Description

FIG. 8

The invention relates to radioelectronics, and can be used in the preparation of acoustoelectronic devices on surface and bulk spherical waves (AB),

An object of the invention is to increase yield.

In FIG. Figures 1–9 show the sequence of operations of the method of manufacturing JQ laziness of elements of devices operating on AB.

A method of manufacturing the elements of devices operating on AB involves forming a photoresist 1 layer on the working surface of a sound duct 2 using a masking f5 layer of 2 bands of strips of the first metal layer 3 by reverse photolithography, forming a dielectric 20 layer C on top of it, additionally applying a layer of photoresist 5, exposing it with side of the surface of the sound duct, working against the full-wave, and developing, spraying the second metal layer,., removing the second metal layer 6 with a photoresist layer.

Example. A centrifugation layer of FP-RN-7 grade 1 with a thickness of 0.8 μm thick (Fig. 1) was applied to the working surface of the sound duct 2 of niobate by centrifugation, followed by drying at 90 ° C for 30 minutes. Then, the layer of photoresist 1 was illuminated through a photomask containing a picture of a group of strips of the first metal layer 35, after which windows were opened in photoresist 1 by manifesting it in 0, KOH (Fig. 2), and its subsequent secondary drying was carried out at 115 ° C within 30 minutes 40 Then, the metal layer 3 (Fig. 3), consisting of a sublayer of nichrome 0.03 μm thick and an aluminum layer 0.15 μm thick, was deposited by magnetron sputtering in argon plasma onto the remaining areas of photoresist 1 and the exposed areas of the working surface of the evukup 2; . In order to suppress crystallization of aluminum oxide during its subsequent oxidation in order to create an oxide layer on the surface of metal strips, germanium (1 $) was introduced into the aluminum of the magnetron target. The pressure in the vacuum chamber was 1-0.5 Pa 55 at a sound duct temperature of 200 C.

wa

Cape carried out an operation- - removal of areas of the photoresist

1 with a layer of metallization on them by holding in a vessel containing a photoresist solvent for 20 minutes and sonication for 2 minutes. As a result, a group of strips of the first metal layer was formed (Fig.). Then, on a working surface of sound duct 2 and on a group of strips of the first metal layer 3, a silicon dioxide film C of a thickness of 0.025 μm was deposited by a method of magnetron sputtering of a silicon target in an oxygen-argon plasma (percentage of oxygen and argon 50 $ / 50 $) (Fig. 5). The resulting structure was then coated with a layer of photoresist

5 (Fig. 6), which was dried and illuminated through a photomask, containing the perimeter of the interdigital transducer (IDT) perimeter, with the illumination source and the photomask located above the surface of the sound duct opposite its working surface. The photo template was combined

with a structure already formed on the working surface so that the group of strips of the first metal layer is completely contained in the photo mask window. Illumination radiation (a wavelength of light of the order of 0.2 μm or less — near ultraviolet) passed through a photomask, through a sound conductor 2 made of lithium niobate (weakly absorbing near ultraviolet radiation) and reached photoresist 5, a transparent thin layer of silicon dioxide also passed. Photoresist 5 was illuminated only in those areas that. were not obscured by stripes of metal of the first group 3 (Fig. 6). The illuminated portions of photoresist 5 were then removed (Fig. 7). After that a layer was applied.

6 metalization, also consisting of a nichrome sublayer (0.03 microns) and an aluminum layer (0.15 microns) (Fig. 8). The regions of the photoresist with the metallization layer were removed by the explosion method, as a result, in the gaps between the strips of metal of the first group, strips of metal of the second group were formed, which completed the process of manufacturing IDTs (Fig. 8).

Another variant of the specific implementation of the above method consisted in manufacturing the same structure (IDT), however, the operation of applying the dielectric layer to the surface of the metal strips of the first group consisted in oxidizing their surface by annealing in the atmosphere (in air) at 00 ° C for 5 minutes. The thickness of the oxide layer formed on the surface of the metal strips (aluminum with the addition of germanium) was again equal. 0.025 μm. As mentioned above, the addition of germanium inhibited the crystallization of the oxide film, which led to an improvement in its insulating properties.

The IDTs manufactured by the proposed method had a gap between adjacent electrodes (between adjacent strips of metal of the first and second groups)} equal to 0.025 μm, which is an order of magnitude smaller than the gap values obtained by the previously known method. The thickness of the dielectric layer varied from point to point within 1% in the case of applying a film of silicon dioxide and 5% in the case of oxidizing the surface of metal strips. In both cases, the dielectric layer was homogeneous, had good morphology and high breakdown voltage. Exactly these

The characteristics made it possible to achieve a $ 80 yield of suitable products when using the described method in laboratory conditions.

F

claims

A method of manufacturing elements of devices operating on acoustic waves, including forming, using a masking layer of a photoresist, on a working surface of a sound duct a group of strips of a first metal layer, spraying a second metal layer, removing part of a second metal layer with a photoresist layer, a development characterized in that, with in order to increase the “yield percent”, after forming a group of strips of the first metal layer by the method of reverse photolithography, dielectric the th layer, on which the photoresist layer is additionally applied, is exposed on the side of the surface of the sound duct, (opposite to the working one, after which development is carried out.

FIG. 4

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