SU1019019A1 - Composition for selectivly etching neodimium monoaluminate film from aluminium - Google Patents

Description

About QP The invention relates to chemical etching of metals and can be used in microelectronics to obtain the configuration of the passive part of thin-film large hybrid integrated circuits. Neodymium monoaluminate is used as a dielectric in thin film capacitors and multilayer thin film switching boards. The configuration of monoaluminate films of neodymium is obtained by the method of photolithography | chemical etching. In this case, it is necessary that the composition for etching the plenons of neodymium monoaluminate does not affect} the films of almines, used as the lower plates of capacitors and current-carrying layers of switching boards. Besides. This composition should provide a uniform edge and a high etching rate of the films with neodymium minate monoal. Known solution 1 used for etching alumina films of the following composition, g / l: Chromium anhydride 60-lAO Phosphoric acid AO-300 However, when etching films of neodymium monoaluminate in this solution, agvominium underneath the film of neodymium mineral aluminate is intensely etched. significant side trimming occurs and the uniformity of the edge of the pattern pattern is disturbed. The closest in technical: essence to the proposed composition is the composition 2j for etching a film of oxides from an alu-Blue substrate, containing phosphoric, acetic, nitric acid as an oxidizer and water, ml: Phosphoric acid 7bO Acetic acid 150 Nitric acid 30 Water50 The known composition is intended for the simultaneous etching of porous alumina and aluminum films. The etching rate of aluminum is 0.26-0.3 µm / min, and alumina 0.5-0.6 µm / min, i.e. The composition is not selective for metallic aluminum films. The rate of etching films. aluminum is only two times lower than the etching rate of an alumina film lying on aluminum films. The aim of the invention is to reduce the etching rate of the aluminum substrate and the side etching. The goal is achieved by the fact that the composition of the D I selective etching of a neodymium monoaluminate film with alomyne, contains a phosphoric acid, yjKcycHyto acid and an oxidizer, additionally contains starch, and chromic anhydride as an oxidizing agent in the following ratio of components, g / l: Phosphoric acid 10 -50 Acetic acid 3-20 Chromic anhydride 20-50 Starch 0.1-1-1 The concentration of chromic anhydride is critical: a deficiency of Cfflj causes phosphoric acid to affect the aluminum film, and an excess causes electrochemical eskoy corrosion in certain parts of the aluminum metallization. . about. ;;. ..,:. ; . . , The introduction of acetic acid and starch-. small ensures uniformity of the edge of the pattern and minimal lateral drainage, and also increases the etching rate. To establish the boundary and optimum values of compote concentrations; The rate of etching and the quality of the microrelief were determined depending on the content of the components. The results of the experiments are given in table. one.

Table 1

How 8IDYO of. 1, the content of JB chromic anhydride composition is less than 26 g; /. , phosphoric acid is less than 10 g / / l, acetic acid is less than 3 g / l, leads to a sharp decrease in the etching rate of the etching of the pryazh cryoaluminate neodymium and an increase in side etching. .-. ..

So, it is optimal to set t the content of the I1 of the complex in ratios, g / l Chromic anhydride 35 acid 35 Acetic acid .10 Starch 0.2

The content of chromic anhydride more than 50 g / l, phosphoric acid more than 50 g / l, acetic acid more than 20. g / l leads to a sharp increase in the etching of aluminum films.

Comparative data processing in the proposed and known compositions are presented in table. 2

- -. .

table 2

The etching rate of aluminum in the proposed composition is 30–200 times lower than the etching rate of mono aluminate films of neodymium.

During processing, a temperature range of 50 ± 5 ° C was chosen. At a temp S 101901 "

Thus, the use of traapea precursors drastically decreases with C, and, with a temperature-controlled composition,

more SyC significantly improved. .. high-quality configurations of films of mo

Vtsy adhesion photoresistively aluminate neodymium deposited on

masks.5 aluminum films.

Claims (1)

COMPOSITION FOR SELECTIVE Etching of a film of neodymium monoaluminate from aluminum containing phosphoric acid, acetic acid and an oxidizing agent, characterized in that, in order to reduce the etching rate of the aluminum substrate and side etching, it additionally contains starch, and chromic anhydride as an oxidizing agent in the following ratio of components g / l: phosphoric acid 10-50 Acetic acid 3-2.0 Chromic anhydride 20-50 Starch 0.1-T