DE2354435A1 - Process for the production of thin layers on substrates - Google Patents

Description

"Process for the production of thin layers on documents "

The invention relates to a method for producing thin layers on heated substrates by chemical means Vapor deposition.

There are "already various methods of chemical vapor deposition known" In so-called evaporators, the temperature of which is higher than the ambient temperature ₉ , suitable substances are heated in such a way that they are due to the vapor pressure that is set

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be absorbed by a carrier gas. That with the starting substances Enriched carrier gas can still be diluted by level currents. This gas mixture, consisting from the starting substances, the carrier gas and, if necessary, the secondary streams, via lines and Valves passed into a reactor, in which on the surface of heated substrates the decomposition of the starting substances and the coating takes place.

When carrying out this process, it has been found to be disadvantageous that in the evaporator when entering or Passing the carrier gas at ambient temperature changes the vapor pressure impermissibly or changes the Partial precipitate starting substances and that in the supply lines, the valves and on the reactor wall some of the starting substances are deposited.

This results in an increased use of the starting substances, longer coating times and a considerable amount of time Maintenance effort and reproducible separation rates can hardly be realized.

There are too. Coating processes and devices known, in which an evaporator attached directly to the reactor is used. "Surrendered with this arrangement in addition to considerable constructive and operational Difficulties also increased in terms of health and safety Requirements. In addition, there is a defined dilution and thorough mixing of the gas mixture difficult or impossible.

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The purpose of the invention is to determine the coating times, the use of the coating material and the maintenance effort to lower.

The invention is based on the object of a method to create, with which a reaction essentially on or in the immediate vicinity of the "substrate to be coated" and the most complete and homogeneous possible deposition of the reaction product on the heated substrates he follows.

According to the invention the object is achieved in that the carrier gas flow and the secondary flows as well as the feed lines and valves are heated so that the temperature is between the evaporation and the decomposition temperature the starting substances and that the gas mixture in the reactor by a heated flushing current is isolated from the reactor wall. The purge stream does not consist of one with the starting substances reacting gas, is heated to the temperature of the carrier gas, passes through a separate gas inlet into the reactor and strokes along the walls of the reactor.

The advantages of the solution according to the invention are above all in the reproducible high separation rate, in the economical consumption of the starting substances and in low levels To see maintenance effort. The starting substances do not condense and / or decompose in the lines,

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Valves or the reactor wall, but only on the substrate. Furthermore, it turns out to be separate from the reactor arranged evaporator as advantageous, since a precise and reproducible gas metering and mixing is possible and the construction of the device for operation and compliance with occupational safety issues creates favorable conditions.

The invention is based on an exemplary embodiment below are explained in more detail.

In order to deposit aluminum oxide Al ₂ O- on a substrate, nitrogen preheated to evaporator temperature is used as a carrier gas and in an evaporator, which ^{is heated to a temperature between 120 and 140 0} G, aluminum isopropylate AL (-1 OCJSr ₇ ) is used as the starting substance. ., enriched.

All piping and valves, as well as the optionally used for dilution of the carrier gas sub-streams are heated to a temperature between 120 and 160 ⁰ O. This temperature interval must be observed to prevent condensation on the one hand and decomposition on the other.

Avoid statutes of the starting substances. The carrier g & s loaded with aluminum isopropylate is centrally let into the reaction space consisting of a closed tube and meets the heated one there Documents · To guide the with aluminum isopropylate loaded carrier gas is heated to a temperature

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nitrogen purge stream preheated to between 120 and 160 ° C so through, an annular gap introduced into the reactor that it brushes along in the immediate vicinity of the reactor wall and prevents the aluminum isopropylate from coming into contact with the reactor wall.

It is also possible to bring ^{the reactor wall to a temperature between 120 and 160 °} C. either in addition to the heated flushing stream or instead of it.

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Claims (2)

Patent claims: • j Process for the production of thin layers on substrates by chemical vapor phase deposition, in which starting substances are absorbed by a carrier gas stream in an evaporator and a gas mixture consisting of the starting substances , the carrier gas and secondary streams used to dilute the carrier gasB, through lines and valves is passed into a reactor, characterized in that the carrier gas stream and the Hebens.tröme as well as the feed lines and the valves are heated in such a way that the temperature is between the evaporation and the decomposition temperature of the starting substances and that the gas mixture in the reactor by a heated flushing flow is isolated from the heater wall. 2. The method of claim 1, characterized in that the spill stream consists of a punch with the Ausgangssub- non-reacting gas, is brought to the tem perature of the carrier gas and secondary streams, actuator enters through a separate gas inlet in the Re and the walls of the reactor . 409837/0668