DE3339625A1 - DEVICE FOR ENRICHING A CARRIER GAS WITH THE VAPOR OF A LITTLE VOLATILE FABRIC - Google Patents

Description

PHILIPS PATENTVERWALTÜNG GMBH PHD 83-104

Device for enriching a carrier gas with the vapor of a low volatile substance

The invention relates to a device for enriching a carrier gas or carrier gas mixture with the steam or the Steaming of a less volatile substance or mixture of substances in the form of small solid particles with a Vessel with a heated interior for receiving the substance or mixture of substances, which is provided with a supply line for the Carrier gas and a discharge line for the enriched carrier gas is provided, the lines in such a way in the Open space inside that the carrier gas through the substance or the mixture of substances during operation of the device flows through.

Such a device is known from DE-OS 31 36 895. The known device consists of one Evaporation vessel with lid. Inside the evaporation vessel there is a sieve on which the Device is a powdery starting material. Below the sieve or in its area is in Evaporation vessel arranged a heating element. Of a

Carrier gas storage container leads a supply line to the evaporator vessel, into which the supply line below the sieve flows out. From the interior of the evaporation vessel above the sieve, a steam discharge line leads to a reactor in which a reactive deposition from the gas phase takes place, in which a CVD process is carried out.

The studies which led to the invention dealt with the enrichment of carrier gases with gases for reactive deposition, especially of rare

earth metals (III B metals) or rare earth metal compounds (III B compounds), especially of thorium and

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XS. PHD 83-104

Thorium compounds, from the gas phase. Since the corresponding starting compounds for the CVD process are usually as organometallic compounds are in powder form at room temperature - only those are light When heated somewhat volatilely - the starting compound becomes a substrate surface with a carrier gas transported on which layers are to be deposited. The carrier gas, preferably a noble gas, in particular argon, flows through a saturator, which is filled with the powdery starting compound and to a suitable one Temperature is heated up.

The device known from DE-OS 31 36 895 has the disadvantage that it has only a short flow path of the Has gas through the gas-forming material. The yield of reaction gas for the CVD process or its Concentrations in the gas flow are correspondingly low.

The invention is based on the object of a device

of the type mentioned at the outset, in particular a saturator, which has a long flow path having.

This object is achieved in that the

Vessel contains a removable, precisely fitting metal body that in at least one outer wall of the metal body at least one groove is incorporated and that this outer wall with an inner wall of the vessel in such a way is in contact that the groove forms said interior space.

In order to achieve the longest possible flow path, the groove must be as long as possible. For this it is useful to that the groove is spiral or zigzag or 35

is meandering.

t PHD 83-104

The outer wall of the metal body, in which the groove is incorporated, is preferably with the bottom of the Vessel in contact. It follows that the groove is preferably in the underside of the metal body is incorporated. But it is also possible to work the groove into the side walls of the metal body.

In order to prevent particles of the substance or mixture of substances from being entrained by the carrier gas, it is expedient to arrange a gas-permeable body between the gas discharge line and the interior.

The device according to the invention has the advantage that it is easy to deal with the finely divided vapor-forming A substance or a mixture of substances, e.g. a powder, can be filled. For example, the filling of a saturator according to the invention is done in the underside of a copper block incorporated groove down to the bottom of a tub or pan just sufficiently filled with the powder V2A stainless steel pressed in. The groove filled in this way is flowed through by the carrier gas during operation.

A spiral design of the groove has the additional advantage that by means of a rotary movement in

Spiral outer direction a dense filling of the grooves with the powder is achieved and at the same time the ground contact Attachment surfaces will be quite good.

Another advantage of the device according to the invention is that its part «
easy to clean.

that its parts after removing the metal body

Some embodiments of the invention are shown in a drawing and will be described in more detail below

explained. In the drawing show:

$ S S'- PHD 83-104

1 shows a saturator in section,

Fig. 2 shows a removable metal body

(Metal insert) with spiral groove and

3 shows a removable metal body

(Metal insert) with meandering groove.

The chronological sequence of the commissioning of the saturator according to Fig. 1 is as follows:

First, fine gas-forming powder is poured into a pan 1 made of stainless steel. Then a precisely Matching copper block 2 with a spiral groove or spiral groove 3 worked into its underside firmly on the Powder pressed on, with a rotary movement against the later flow direction, and matching the carrier gas inlet 4 anchored with a pin (not shown). The gas outlet 5 is in the middle of the copper block and contains a mesh screen and AlpO ^ wool stuffed in front of it. This combined sieve is intended to prevent the powder from escaping.

A further copper insert, e.g. a hollow cylinder with a closure and outlet opening, can be placed over the copper block 2 (not shown), inserted and with a bayonet lock with firm pressure on the saturator block be clamped. The space between the copper insert and the saturator block then provides a mixing chamber for others CVD starting gases. The substrate to be coated can then be arranged in a reactor via their outlet nozzle (not shown).

In Fig. 2 is a metal body 2 with a spiral groove and in Fig. 3 is a metal body 2 with a meandering groove shown, the carrier gas inlet with 4 and the gas outlet with 5 are designated.

PHD 83-104

The outer walls of the saturator and reactor are made of V2A stainless steel and are designed to be highly vacuum-tight. she are in a furnace with separate heating for the saturator and for the reactor and the mixing chamber. Latter are at a slightly higher temperature than the saturator during operation, around a wall precipitation of the III B starting compound to avoid. After a series of coatings, the saturator assembly and cleaning is usually necessary refilling with the starting compound is necessary, since many of the powdered organometallic compounds used Starting compounds already begin to dissociate in the vicinity of the melting point, but also the highest there have realizable vapor pressure in the long run. In addition, successive decomposition through contact with the during Aggressive compounds are formed by CVD processes

(e.g. WF _C and HF), ο

The entire arrangement can be taken apart for cleaning purposes in a few simple steps and brushed in

diluted solutions of detergents are cleaned, followed by rinsing with water and ethanol.

When using the saturator, thorium acetylacetonate (Th (AA) ₄ ) or

Thorium trifluoroacetylacetonate (Th (3FAA) ₄ ) and argon as the carrier gas. The saturator was at the filling with Th (AA) ₄ 16O ° C + 5 ° C or 100 to 120 ⁰ C at Th (3FAA) -filling _4; the reactor ^{temperature was 20 0} C above the saturation temperature. As deposition rates for

the thorium-containing layers were achieved about 0.1 to 0.4 _{μm / min, which for Th (AA) 4} decreased sharply for the third coating in each case and for Th (3FAA) ₄ about 6 coatings long could be realized, with the

The duration of a coating was a maximum of 4 hours. 35

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Claims (4)

PHD 83-104 claims 1. Device for enriching a carrier gas or carrier gas mixture with the steam or vapors of a less volatile substance or substance mixture present in the form of small solid particles, with a vessel with a heated interior for receiving the substance or mixture of substances with a supply line for the Carrier gas and a discharge line for the enriched carrier gas is provided, the lines in such a way in the Open space inside that the carrier gas through the substance or the mixture of substances during operation of the device flows through characterized in that the vessel (1) contains a removable, precisely fitting metal body (2), that a groove (3) is worked into at least one outer wall of the metal body and that this outer wall is in contact with an inner wall of the vessel in such a way that the Groove forms the said interior. 2. Device according to claim 1, characterized in that the groove (3) is wound in a spiral or zigzag or meander shape. 3. Apparatus according to claim 1 or 2, characterized in that the outer wall of the metal body (2) _? in which the groove (3) is incorporated, is in contact with the bottom of the vessel (1). 4 ο Device according to claim 1, 2 or 3, characterized in that between the gas discharge line (5) and a gas-permeable body is arranged in the interior (3). BATH ORIGINAL