Method of making quartz containers. RU patent 2504602.

FIELD: chemistry.

SUBSTANCE: method of making quartz containers with a protective carbon coating for high-temperature processes involves depositing a polymer film on the working surface of the quartz container, followed by annealing in an inert atmosphere. Said film is deposited on the working surface of the quartz container by depositing polyhexamethylene guanidine hydrochloride or polydiallyldimethylammonium chloride from its 7-10% aqueous solution with pH 1-3 and subsequent annealing in an inert atmosphere at 900-1000°C for 30-60 minutes.

EFFECT: improved quality of protective coatings on the surface of quartz containers owing to high density and strength thereof while preventing reaction molten material with working walls of a container of any shape and reduced contamination of the obtained material with diffusing chemical impurities from quartz.

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The invention relates to methods of manufacture of quartz containers with protective carbon coating for synthesis and crystallization of melts of semiconductor materials, and also for reception of especially pure metals and polymetallic alloys.

There is a method of manufacturing of the growth of the container in the form of quartz boats from raw quartz tube with subsequent sedimentation on the working surface type «Aquadag» of the decomposition products of gas-vapor mixture of toluene in a stream of nitrogen at a temperature of 1050°C (Beels R, De Sutter W. Pyrolytic coating of quartz and ceramic vessis used for zone melting // Jornal of Scientific Instrument. Vol.37. №10, October 1960, p.397).

Disadvantage of this method is complex and expensive technology manufacture of containers with the coating, which in the spongy layer does not eliminate the interaction of molten material with the walls. Thick layers (>20 mm), representing a plaque soot («lamp soot»)are destroyed by contact with a solution-melt and pollute the grown crystals of carbon.

There is a method of manufacture of quartz container in the form of a Cup with conical bottom (tuba) and application of the internal surface of the container carbon coating deposition decomposition products-vapor mixture of acetone in a stream of nitrogen at a temperature of 900 to 1170°C (Qingrun Century, G. Ju, Jinyi W., JI'an C. Carbon Film Coating Used in CdZnTe Cristal Growth. Rare Metals. Vol.16, no. 2, april 1997, p.114-116). The method adopted for similar.

This method is characterized by complicated and explosive technology, because in a heated reactor, the high-temperature decomposition of acetone vapor and precipitation on a quartz container surface of a thin layer of carbon-containing. Upon receipt of crystals in this container, there is a partial interaction of molten material with walls and crystal formation with high density of structure defects. The increase in the thickness of the protective layer of carbon-containing up to 25-30 microns leads to the mechanical stresses on the boundary with the walls of quartz and destruction of coatings in contact with the melt.

There is a method of composite silicon-oxide carbon coatings by pyrolysis of thin polymer films siloxanes (Patent RU 2370568 30.04.2008 published 20.10.2009 (prototype)). But this type of coverage cause doping of high-purity silicon material, and is connected with the aggressive use of substances during the formation of coatings.

The technical result is the improvement of the quality of protective coatings on quartz surfaces of containers by increasing their density and strength, providing prevention of interaction of molten material with the workers of the walls of the container any form and reduction of pollution of the material obtained diffusing impurities of chemical elements from quartz.

The technical result is achieved by a method for the manufacture of quartz containers with protective carbon coating for high-temperature processes, including drawing on working surface of quartz container polymer film with the subsequent annealing in an inert atmosphere, the application of a film on a working surface of a quartz container is carried out by deposition or of his 7-10%aqueous solution with pH 1-3, and subsequent annealing in an inert atmosphere is carried out at 900-1000°for 30-60 minutes.

Summary of the invention consists in that the high-molecular oligomers polymer amines effectively fixed to the surface of the quartz glass through education, multicenter, hydrogen and electrostatic relations between pgmg and surface hydroxyl groups of quartz glass. As a result of subsequent annealing on quartz surface a thin layer of carbon coating.

For the deposition of the polymer film on the surface of the quartz glass by wetting, drying under normal conditions and subsequent annealing in the inert atmosphere of use or .

Most uniform film of polymer Amin on the surface of the quartz glass is produced in the utilization of 7-10%solution of polymer amine with a pH 1-3. The use of more concentrated solution affects the spreading of the solution on the walls of quartz container, and after annealing are layers. Application of more diluted solution leads to the formation of thin films, which do not possess sufficient strength.

At pH>3 there is a decrease in adhesion of polymer chains to the quartz; at pH<1 there is a formation of polymeric agglomerates and deterioration of the homogeneity of the polymer layer.

Pyrolysis annealing of carbon-containing polymer films in the inert atmosphere of conduct in the temperature range of 900-1000°C. At temperatures below 900 C and time less than 30 minutes, a formation of a thin inhomogeneous coatings that decomposes in contact with the melt, contaminating his carbon additives. Conducting annealing in an inert atmosphere at temperatures above 1,000 degrees C and time of more than 60 minutes does not lead to a significant improvement in the quality of carbon-containing coating, but leads to additional and unnecessary expense.

Implementation of the proposed method is illustrated by the following examples.

Example 1.

From quartz tubes (d EXT. =58 mm; L servant =600 mm; Art. d =2.5 mm) produce boat, pickle its 10%-s ' water solution of hydrofluoric acid brand OFS. In boat made of poured 7%aqueous solution (), containing 0.1 ml of concentrated hydrofluoric acid. A solution merge, boat turned upside down and leave to dry. Boat coated with a polymer film are placed in a reactor resistance furnace and vacuum up to 1.5 .10 -3 mm Hg Then reactor is filled with argon and in a stream of argon (1-100 ml/min) conduct annealing boats coated with a polymer film at a temperature of 900 OC for 30 minutes. Then the temperature in the reactor of the furnace reduces to room temperature, and pull a boat with the generated a protective coating.

Received a boat with the formed protective carbon coating serves on the plot of the band cleaning Germany. In a boat with a protective coating load 1 kg Germany polycrystalline semiconductor purity. Spend three passes of the molten zone for the control of purity of the coating. After the implementation process produces control (visual) of the container, cover and analysis of the pure material.

State of the container and cover:

- no areas on the inner and outer surfaces of the walls;

- no destruction of the coating on the walls and the erosion of the surface.

Parameters of cleaned ingot:

- absence of visible traces the interaction of an ingot with the walls of the container, mirror-smooth bottom ingot;

- absence of cracks and other structural defects on the surface, formed by the interaction of the melt with the walls of quartz.

Parameters of the crystal:

Ingot was subjected to the measurement of specific electric resistance at the temperature of liquid nitrogen the entire length of the well-known method. As an assessment of the purity of the obtained material used level of specific electrical resistance of more than 1000 Ohm*cm, which corresponds to the level of electrically active impurities, not more than 10 to 11 cm 3 :

- the share of ingot, to the desired level of 33%, which indicate PA sufficient degree of cleanliness of surface and normal conduct of the trial zone cleaning;

Example 2.

From quartz tubes (d EXT. =58 mm; L servant =600 mm; Art. d =2.5 mm) produce boat, treated her with a 10%aqueous solution of hydrofluoric acid brand OFS. In boat made of poured 7%aqueous solution , (pgmg) containing 0.1 ml of concentrated hydrofluoric acid. A solution merge, boat turned upside down and leave to dry. Boat coated with a polymer film are placed in a reactor resistance furnace and vacuum up to 1.5 .10 -3 mm Hg Then reactor is filled with argon and in a stream of argon (1-100 ml/min) conduct annealing boats coated with a polymer film at a temperature of 900 OC for 30 minutes. Then the temperature in the reactor of the furnace reduces to room temperature, and pull a boat with the generated a protective coating.

Received a boat with the formed protective carbon coating serves on the plot of the band cleaning Germany. In a boat with a protective coating load 1 kg Germany polycrystalline semiconductor purity. Spend three passes of the molten zone for the control of purity of the coating. After the implementation process produces control (visual) of the container, cover and analysis of the pure material.

Parameters of the crystal:

Ingot was subjected to the measurement of specific electric resistance at the temperature of liquid nitrogen the entire length of the well-known method. As an assessment of the purity of the obtained material used level of specific electrical resistance of more than 1000 Ohm*cm, which corresponds to the level of electrically active impurities, not more than 10 to 11 cm 3 :

- the share of ingot, to the desired level of 32%, which indicates a sufficient degree of cleanliness of surface and normal conduct of the trial zone cleaning.

The quality of the material obtained in example 2 similarly, the quality of the material obtained in example 1. The data are given in table 1.

Received a protective coating on the surface of the quartz container, ensure the implementation process of the band cleaning high-pure germanium with access to the part of high-purity (the content of electrically active impurities, not more than 10 to 11 cm 3 ) at the level of 33% by weight of the feed material.

Thus, the claimed method can significantly simplify the process of obtaining carbon coating the inner walls of the containers made of quartz glass of any configuration, increase the density and durability of coating to enhance the reliability of containers repeated their use in the processes of zonal cleaning and cultivation of Germany.

The use of quartz container with protective coating obtained claimed process materials with high electro-physical parameters due to:

- prevent interaction of molten material with a working surface of quartz is due to the germanium coating;

- reduction of pollution of the crystal diffusing impurities from quartz due to the high purity, inertia, and cover density.

Results of tests

Type of container

Concentration of polymer, % of mass.

Exposure time, min

Annealing time, min

Temperature annealing C

Term of service, the number of heats

Output in extremely pure product in the process of the band cleaning Germany, % of mass.

Graphite brand 3-OFS

Pyrolytic (analogue)

Quartz coated

Quartz coated

Quartz coated

Quartz coated

Quartz coated pgmg

Quartz coated pgmg

Quartz coated pgmg

Quartz coated pgmg

Coverage of (prototype)

Method of manufacture of quartz containers with protective carbon coating for high-temperature processes, including drawing on working surface of quartz container polymer film with the subsequent annealing in an inert atmosphere, characterized in that application of a film on a working surface of a quartz container is carried out by deposition or of his 7-10%aqueous solution with pH 1-3 and subsequent annealing in an inert atmosphere at 900-1000°for 30-60 min