RU2419175C2 - Method of processing substrates in liquid etching agent - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: substrates are processed in a liquid etching agent consisting of hydrofluoric acid (HF), ammonium fluoride (NH₄F) and deionised water (H₂O) with components in ratio of 1:2:5 at room temperature for 4±1 minutes. The processing quality is assessed under a microscope based on presence of flashing points, the number of which was equal to 5.

EFFECT: ensuring quality of the pattern, uniform etching and shorter process.

Description

The invention relates to the manufacturing technology of power silicon transistors and integrated circuits (ICs), in particular to methods for processing substrates to form contact windows.

Known processing methods, the essence of which is to etch the surface of the substrates in various etchants (nitric acid, acetone, methyl ethyl ketone, sulfuric acid, etc.) [1].

The main disadvantages of these methods are uneven etching, uneven relief of the pattern and the duration of the process.

The aim of the invention is to ensure the quality of the pattern, uniform etching and reducing the duration of the process.

This goal is achieved in that the treatment is carried out in an etchant of hydrofluoric acid (HF), ammonium fluoride (NH ₄ F) and deionized water (H ₂ O) in a ratio of 1: 2: 5 at room temperature for 4 ± 1 minutes, then washing lead in two baths with a four-sided overflow of deionized water at a flow rate of 400 l / h, washing time - 5 minutes in each of the baths. Drying is carried out within 3 minutes. The quality of processing is carried out under a microscope for the presence of luminous dots, they amounted to 5 pieces.

The essence of the method lies in the fact that with liquid etching, the best quality of the pattern is provided by buffer etchants, since it is easier to control the slow etching process, for example, HF: NH ₄ F: H ₂ O = 1: 2: 5:

SiO ₂ + 2HF → SiF ₄ + 2H ₂ O;

NH ₄ F → NH4 ⁺ + F ^- ;

SiF ₄ + 2F ^- → (SiF6) ^-2 .

Ammonium fluoride dissociating in the solution binds gaseous silicon tetrafluoride into a stable ion, which prevents the rapid release of silicon tetrafluoride bubbles, which have a hydromechanical effect on the photoresist mask and promote peeling.

The invention is confirmed by the following examples:

EXAMPLE 1. The process is carried out on a chemical treatment unit (Lada-1), at room temperature in the ratio of components:

HF: NH ₄ F: H ₂ O = 0.5: 1: 3

The duration of the process is 6 ± 1.

The quality of processing is carried out under a microscope for the presence of luminous dots, they amounted to 7 pieces.

EXAMPLE 2. The method is carried out analogously to example 1. The process is carried out in a ratio of components:

HF: NH ₄ F: H ₂ O = 1: 1.5: 4

The duration of the process is 5 ± 1.

The quality of processing is carried out under a microscope for the presence of luminous dots, they amounted to 6 pieces.

EXAMPLE 3. The method is carried out analogously to example 1. The process is carried out at a ratio of components:

HF: NH ₄ F: H ₂ O = 1: 2: 5

The duration of the process is 4 ± 1.

The quality of processing is carried out under a microscope for the presence of luminous dots, they amounted to 5 pieces.

As follows from the results of the experiments, one of the most effective etchants is an etchant consisting of the following components of hydrofluoric acid (HF), ammonium fluoride (NH ₄ F) and deionized water (H ₂ O) in a ratio of 1: 2: 5.

Thus, the processing of substrates in a liquid etchant provides uniform etching, improving the quality of the pattern and reducing the duration of the process.

Information sources

1. I.A. Malysheva. Technology for the production of integrated circuits. M .: Radio and communications, 1991.

Claims (1)

A method of treating substrates in a liquid etchant, comprising treating the surface of the substrates with an etchant, which includes hydrofluoric acid (HF), ammonium fluoride (NH ₄ F) and deionized water H ₂ O, characterized in that the substrates are treated in an etchant consisting of hydrogen fluoride acid (HF), ammonium fluoride (NH ₄ F) and deionized water (H ₂ O) with a component ratio of 1: 2: 5 and a time of 4 ± 1 min.