The method of etching of single crystals of lithium tantalate

 

(57) Abstract:

The invention relates to a method of hydrothermal etching, providing for the establishment of environmentally friendly methods of etching of single crystals of lithium tantalate, used in electronic equipment. Allows etching of large single crystals of more than 2 10 10 mm (crystals when the etching does not crack), while avoiding the need to use expensive thermally inactive materials such as platinum, iridium, allowing to reduce the cost of the process and to increase the etching rate. The essence of the method consists in the processing of single crystals of lithium tantalate under hydrothermal conditions at 150 To 300°C and a pressure not less than 50 ATM, and as a pickling solution using aqueous solutions of a mixture of one of the acids H3PO4, HNO3and one of the salts MeNO3, MeF, MeHF2where IU alkaline metal, or in aqueous solutions of one of the salts MeNO3, MeF or MeHF2or in aqueous MeOH solution of alkali and salt MeNO3.

The invention relates to a method of hydrothermal etching process, providing for the establishment of environmentally friendly methods of etching tantalum single crystals the crystals of tantalum lithium [1] includes etching in molten potassium hydroxide at 3600,2aboutC.

The disadvantage of this method is low sustainability as a couple of provide the Etchant enter the atmosphere, and not a high etching rate.

Closest to the invention is a method of etching tantalum single crystals of lithium [2] including machining and etching in a solution based on the fluorine-containing reagent. The substrate is treated to provide the Etchant from F2up to 240aboutC.

The disadvantage of this method is the low environmental friendliness, because at high temperatures a large number of provide the Etchant vapors emitted into the atmosphere.

The advantage of the proposed method hydrothermal etching is that there is the possibility of etching of large single crystals of more HH mm (crystals are not dissolved during etching), and there is no need to use expensive inactive temperature-resistant materials such as platinum, iridium.

The technical effect is environmentally friendly method of hydrothermal etching, allowing to increase the etching rate and the cost of the etching process.

The method is implemented as follows.

Samples of single crystals of the preparation of the etching solution using reagents brands of reagent-grade or analytical grade. The solutions are consistently in a separate box, diluted with 90% N3RHO4up to 25% In another 25 g of NaNO3dissolved in 50 g of N2Oh, i.e., prepare a 25% solution of NaNO3. The obtained solutions are merged and mixed at room temperature. The resulting mixture is poured into a lined Teflon autoclave batch. The autoclave is sealed and set in a resistance furnace where it is heated to 150-300aboutC at a pressure of at least 50 atmospheres. At lower settings the etching rate drops sharply. Higher settings require more complex equipment. At the end of the process, the sample is washed with distilled water and dried with filter paper. The result of etching the surface of the sample becomes transparent. The etching rate of 0.9 μm/min

P R I m e R 1. The sample was filled with an aqueous solution containing 40% HNO3and 10% RbNO3, was heated to 250aboutC at a pressure of 300 atmospheres. In the matte surface has become more transparent. The etching rate equal to 0.7 μm/min

P R I m m e R 2. The sample was filled with an aqueous solution containing 20% HNO3and 10% NaF, was heated to 200aboutC at a pressure of 300 atmospheres. The result is. brezec was filled with an aqueous solution containing 10% HNO3and 20% KHF2, was heated to 270aboutC at a pressure of 200 ATM. In the matte surface has become more transparent. The etching rate of 1.0 μm/min

P R I m e R 4. The sample was filled with an aqueous solution containing 10% LiNO3and 20% of NaF, and was heated to 300aboutC at a pressure of 500 ATM. In the matte surface was transparent. The etching rate of 0.6 μm/min

P R I m e R 5. The sample was filled with an aqueous solution containing 45% NaNO3and 10% KHF2, was heated to 200aboutC at a pressure of 350 ATM. In the matte surface has become more transparent. The etching rate of 0.9 μm/min

P R I m e R 6. The sample was filled with an aqueous solution containing 40% KOH and 25% KPO3, was heated to 100aboutC at a pressure of 50 ATM. In the matte surface has become more transparent. The etching rate of 0.8 μm/min

P R I m e R 7. The sample was filled with an aqueous solution containing 20% KHF2, and was heated to 280aboutC at a pressure of 150 ATM. In the matte surface has become more transparent. The etching rate of 1.0 μm/min

The METHOD of ETCHING of single CRYSTALS of LITHIUM TANTALATE, on malinich conditions at 150 300oWith not less than 50 ATM, and as an etching solution using the solution of the following composition (IU - alkali metal), wt.

H3PO420 60

MeNO320 60

H2O Rest

or

HNO320 60

MeNO320 60

H2O Rest

or

HNO310 60

MeF 10 60

H2O Rest

or

HNO310 70

MeHF 10 70

H2O Rest

or

MeNO310 70

MeF 10 70

H2O Rest

or

MeNO310 70

MeHF 10 70

H2O Rest

or

MeOH 20 60

MeNO320 80

H2O Rest

or

MeHF > 10

H2O Else

 

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2 ex

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2 dwg, 1 tbl

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