SU1070205A1 - Solution for depositing rhenium coatings - Google Patents

Abstract

SOLUTION FOR DEPOSITION OF RENIUM COATINGS, containing ammonium perrhenate, differs in that, in order to ensure durable stenosis of silicon-based coatings, it additionally contains caustic soda in the following ratio of components, g / l: Ammonium Perrhenate 20-30. natr15-20

Description

The invention relates to the removal of metallic coatings on nonmetallic materials, in particular rhenium coatings on silicon.

A known solution for the electrolytic precipitation of rhenium containing ammonium perrhenate, hydrofluoric acid, and caustic soda 111.

However, hydrogenation of the resulting precipitate leads to its loosening and makes it impossible to obtain coatings on silicon.

Closest to the proposed technical essence and the achieved result is a solution for the deposition of rhenium coatings containing ammonium perrhenate and formaldehyde sulfoxypate as a reducing agent, in which the pH is maintained equal to 2.5-4.5 by adding acid 21.

However, the known solution does not allow to obtain firmly adhered coatings on silicon.

The purpose of the invention is to provide a strong adhesion of coatings to a silicon base.

This goal is achieved by the fact that the solution for the deposition of rhenium coatings containing ammonium perrhenate, additionally contains caustic soda in the following ratio of components, g / l:

Ammonium perrhenate 20-30

Caustic soda 15-20

The process of obtaining rhenium coatings is carried out by immersing the substrate in it and holding it for a certain time at a pH of 11.812.5 and a temperature of 90-100 ° C.

The proposed solution allows to obtain coatings of a thickness of 500-700 A on silicon, which can be used as barrier layers and prevent breakdown of the transition.

The solution is prepared by dissolving ammonium perrhenate in water and adding the required amount of caustic soda to the solution. The prepared solution must be stored in plastic or fluoroplastic containers. An increase in the concentration of ammonium perrhenate in the solution above 30 g / l, as well as a decrease in its concentration of less than 20 g / l leads to a decrease in the adhesion of the rhenium coating. When the concentration of ammonium perrhenate is less than 10 g / l, the process of precipitation of rhenium is stopped. An increase in the concentration of caustic soda over 20 g / l leads to etching of the silicon surface and a decrease in the adhesion of coatings. A decrease in the concentration of caustic soda of less than 15 g / l decreases the deposition rate, and when the concentration of caustic soda is less than 6 g / l, the coating deposition process stops.

The solution is not recommended to be used at a temperature below 90, as this leads to a decrease in the rate of conviction of rhenium coatings. A similar effect has a lower pH of the solution less than 10.5. At pH values greater than 12.5, the adhesion of the coating also decreases due to the etching of the silicon surface.

Before coating, the silicon substrate must be treated in a solution of hydrofluoric acid (48% HF) for 10 seconds, and then rinsed in distilled water.

The use of the proposed solution can be illustrated by the examples presented in table. one.

Table 1

Silicon grade KDB-0.1 substrates KDB-2.0 KDB-0.3

1 temperature, ° С

pH

Time, min

Coating thickness, Base adhesion, - ,, r / MMi

base film is destroyed EFC-10,0 CEF-0.2 CEF-1.0 CEF-CEF1, 0 20.0 - Composition and properties of the solution g ". .VriaAifiLrTiiKiHr CCTVTP- Light absorption coefficient,% Coating grain size, i 200-500 200 Poreness of coating without protection;

As can be seen from the table, the adhesion of the applied coatings to the silicon substrate is rather large. The coating is not mechanically wiped off (the substrate can be taken with tweezers) and can be subjected to repeated washing, moreover, the coating is evenly and does not have through pores. The uniformity of the deposition of the ray in the window dielectric coating, defined for example 3, is presented in Table. 2, where dj is the thickness of the rhenium coating in the central part of the window, d / (is the thickness of the rhenium coating at the periphery. The rhenium coatings deposited using the proposed solution can be used in radio electronics, as well as in the manufacture of semiconductor devices and integrated circuits.

Table

.1.4-1.6 1.4-1.6 1, Li-.iJ..j .... Lf b in 500200-500 200-500 200-500 200-500 200-200 ;;;; : JlP5 P j H2ie table. 1 Indicators by examples. - - - - -. - - -, 500 500 Bespo-Bespo-Bespo-J, Q Pista Pista Pista ..

Claims (1)

The solution for the precipitation of rhenium coatings containing ammonium perrhenate is distinguished by the fact that, in order to ensure strong adhesion of the coatings to the silicon base, it additionally contains sodium hydroxide · 'in the following ratio of components, g / l: Ammonium perrhenate 20-30. Caustic soda 15-20