Preparation method of small-particle-size high-purity hafnium tetrachloride

Abstract

This invention relates to a method for preparing small-particle-size, high-purity hafnium tetrachloride, applicable to the field of integrated circuit semiconductors. The method includes the following steps: Step 1, adding raw material hafnium tetrachloride to a sublimation apparatus under a protective gas atmosphere, and collecting the product fraction under low vacuum; the sublimation temperature is 240-280℃; the high-boiling-point temperature is 200-230℃, the product temperature is 130-160℃, and the low-boiling-point temperature is 50-110℃; Step 2, sampling the product fraction collected in Step 1 in a glove box and repeating the above operation multiple times for sublimation, ultimately obtaining a high-purity hafnium tetrachloride product. This application ensures that the collected hafnium tetrachloride has a purity of 99.999% or higher, ultimately forming small-particle-size hafnium tetrachloride, reducing the content of inorganic metal elements such as aluminum, iron, and zirconium in the hafnium tetrachloride, thus serving as a high-purity precursor to meet production requirements.

Description

Technical Field

[0001] This invention relates to the field of high-purity semiconductor materials, specifically to a method for preparing small-particle-size high-purity hafnium tetrachloride. Background Technology

[0002] Various precursors are deposited to form metal-containing thin films. With advancements in manufacturing processes, transistors and capacitors on chips are becoming increasingly smaller, and traditional silicon oxide or silicon nitride dielectric layers can no longer meet the demands of high-end processes. Hafnium oxide, as a high-k dielectric, can provide higher capacitance values ​​at the same physical thickness, making it one of the most critical and fundamental materials in the modern semiconductor industry. Hafnium tetrachloride, as a major precursor of hafnium, can stably prepare hafnium oxide thin films and has attracted widespread attention.

[0003] The production of hafnium tetrachloride primarily uses hafnium oxide as a raw material, reacting it with chlorine gas. The synthesized hafnium tetrachloride contains certain amounts of various metal chloride impurities, such as aluminum chloride, ferric chloride, and zirconium chloride. Hafnium tetrachloride is typically produced in powder form. However, during the sublimation purification process, the sublimation gas stream encounters low temperatures and easily forms film or flake-like materials that adhere to the wall of the collection tube, making them difficult to collect. Simultaneously, the sublimation gas stream carries a certain amount of high-boiling-point solid particles. The semiconductor industry demands increasingly higher purity raw materials; only high-purity hafnium tetrachloride can meet market requirements. Summary of the Invention

[0004] This invention mainly provides a method for preparing small-particle-size, high-purity hafnium tetrachloride, resulting in high product purity and minimal loss during the sublimation process of hafnium tetrachloride.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for preparing small-particle-size, high-purity hafnium tetrachloride includes the following steps: Step 1: Add hafnium tetrachloride to the sublimation equipment under a protective gas atmosphere, and collect the product fraction under low vacuum. The sublimation temperature is 240-280℃; the high boiling point temperature is 200-230℃, the product temperature is 130-160℃, and the low boiling point temperature is 50-110℃. Step 2: Sample the product fraction collected in Step 1 in the back-end glove box and repeat the above operation for multiple sublimations to finally obtain high-purity hafnium tetrachloride product.

[0006] Preferably, in step 1, the raw material hafnium tetrachloride is added to the sublimation equipment in the front glove box, and in step 2, the sampling process in the rear glove box is carried out under the protection of a protective gas.

[0007] Preferably, the sublimation device is provided with a sublimation end and a receiving end, and a filter and an electromagnetic vibrator are installed between the sublimation end and the receiving end.

[0008] Preferably, the filter material is molybdenum or tantalum, and the filter mesh size is ≥800 mesh.

[0009] Preferably, the electromagnetic vibrator has a vibration frequency of 500-2000 times / minute.

[0010] Preferably, the water and oxygen levels in the front and rear glove boxes are <0.1 ppm.

[0011] Preferably, the raw material hafnium tetrachloride is in powder form with a purity of not less than 99%.

[0012] Preferably, the vacuum degree of the low-vacuum sublimation in step 1 is 100-150 Pa.

[0013] Preferably, the protective gas is one of nitrogen, argon, or helium.

[0014] Preferably, the number of sublimation processes in step 2 is 2-4 times, the purity of the high-purity hafnium tetrachloride product is not less than 99.999%, and the particle size of the product is 78.3μm-91.5μm.

[0015] The beneficial effects of applying the above-mentioned inventive technology are as follows: This invention purifies solid materials using a low-vacuum decompression sublimation process, which allows for easy pressure control and ensures that the collected hafnium tetrachloride achieves a purity of over 99.999%. The sublimation process incorporates a filter to effectively remove high-boiling-point solid particles. An electromagnetic vibrator alters the nucleation state of the product, disrupting gas stability and causing the product to nucleate in the gas phase, generating small-particle products. Operation under protective gas conditions in a glove box ensures that the product does not absorb moisture, hydrolyze, or corrode. This significantly reduces the content of inorganic metals such as aluminum, iron, and titanium in hafnium tetrachloride, making it a suitable precursor for molybdenum-containing thin films, meeting production requirements. Detailed Implementation

[0016] Example 1

[0017] A method for preparing small-particle-size, high-purity hafnium tetrachloride includes the following steps: The water and oxygen content in the front and rear glove boxes is replaced until it is <0.1ppm. In the front glove box, 100g of 99% pure hafnium tetrachloride is weighed and placed in the sublimation apparatus. The sublimation temperature is set to 260℃, the high-boiling-point zone temperature to 200℃, the product zone temperature to 130℃, and the low-boiling-point zone temperature to 50℃. The sublimation apparatus is equipped with a sublimation end and a receiving end, with a filter and an electromagnetic vibrator installed between them. The electromagnetic vibrator vibrates at a frequency of 500 times / minute, and the filter material is molybdenum or tantalum with a mesh size of 800.

[0018] Set the heating parameters according to the above temperature settings, turn on the vacuum system of the sublimation equipment, and when the pressure gauge shows a pressure of 120 Pa, start the automatic heating program and set the sublimation time to 3 hours.

[0019] After sublimation, the system automatically stops heating and cools down. Once the system returns to room temperature, nitrogen gas is introduced to bring it to atmospheric pressure. Hafnium tetrachloride is collected in the product area.

[0020] The collected hafnium tetrachloride was placed from the rear glove box into the sublimation apparatus, and the above operation was repeated once. The final product was a colorless crystalline powder, weighing 83g, with a yield of 83%. ICP-MS analysis showed a purity of 99.999%. Particle size analysis revealed a volume average diameter of 91.5μm.

[0021] Example 2

[0022] A method for preparing small-particle-size, high-purity hafnium tetrachloride includes the following steps: The front and rear glove boxes are purged until the water and oxygen content is <0.1ppm. In the front glove box, 100g of 99% pure hafnium tetrachloride is weighed and placed in the sublimation apparatus. The sublimation temperature is set to 280℃, the high-boiling-point zone temperature to 215℃, the product zone temperature to 140℃, and the low-boiling-point zone temperature to 70℃. The sublimation apparatus is equipped with a sublimation end and a receiving end, with a filter and an electromagnetic vibrator installed between them. The electromagnetic vibrator vibrates at a frequency of 1500 times / minute, and the filter material is molybdenum or tantalum with a mesh size of 800.

[0023] Set the heating parameters according to the above temperature settings, turn on the vacuum system of the sublimation equipment, and when the pressure gauge shows a pressure of 100 Pa, start the automatic heating program and set the sublimation time to 3 hours.

[0024] After sublimation, the system automatically stops heating and cools down. Once the system returns to room temperature, nitrogen gas is introduced to bring it to atmospheric pressure. Hafnium tetrachloride is collected in the product area.

[0025] The collected hafnium tetrachloride was placed from the rear glove box into the sublimation apparatus, and the above operation was repeated twice. The final product was a colorless crystalline powder, weighing 78g, with a yield of 78%. ICP-MS analysis showed a purity of 99.999%. Particle size analysis revealed a volume average diameter of 78.3μm.

[0026] Example 3

[0027] A method for preparing small-particle-size, high-purity hafnium tetrachloride includes the following steps: The front and rear glove boxes are purged until the water oxygen content is <0.1ppm. In the front glove box, 100g of 99% pure hafnium tetrachloride is weighed and placed in the sublimation apparatus. The sublimation temperature is set to 240℃, the high-boiling-point zone temperature to 230℃, the product zone temperature to 160℃, and the low-boiling-point zone temperature to 110℃. The sublimation apparatus is equipped with a sublimation end and a receiving end, with a filter and an electromagnetic vibrator installed between them. The electromagnetic vibrator vibrates at a frequency of 2000 times / minute, and the filter material is molybdenum or tantalum with a mesh size of 800.

[0028] Set the heating parameters according to the above temperature settings, turn on the vacuum system of the sublimation equipment, and when the pressure gauge shows a pressure of 150 Pa, start the automatic heating program and set the sublimation time to 3 hours.

[0029] After sublimation, the system automatically stops heating and cools down. Once the system returns to room temperature, nitrogen gas is introduced to bring it to atmospheric pressure. Hafnium tetrachloride is collected in the product area.

[0030] The collected hafnium tetrachloride was placed from the rear glove box into the sublimation apparatus, and the above operation was repeated three times. The final product was a colorless crystalline powder, weighing 76g, with a yield of 76%. ICP-MS analysis showed a purity of 99.999%. Particle size analysis revealed a volume average diameter of 85.1μm.

[0031] Comparative Example 1 The difference between this comparative example and Example 1 is that the automatic heating program is activated when the pressure gauge displays a pressure of 101325 Pa.

[0032] The final product was a colorless crystalline powder, weighing 3.1g, with a yield of 3.1%. ICP-MS analysis showed a purity of 92.5%. Particle size analysis revealed a volume average diameter of 87.3μm.

[0033] Comparative Example 2 The difference between this comparative example and Example 1 is that there is no electromagnetic vibrator in the sublimation device.

[0034] The final product was a colorless crystalline powder, weighing 67g, with a yield of 67%. ICP-MS analysis showed a purity of 99.97%. Particle size analysis revealed a volume average diameter of 247.9μm.

[0035] Comparative Example 3 The difference between this comparative example and Example 1 is that there is no front glove box and no rear glove box.

[0036] The final product was a colorless crystalline powder, weighing 42g, with a yield of 42%. ICP-MS analysis showed a purity of 98.2%. Particle size analysis revealed a volume average diameter of 187.3μm.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing small particle size high purity hafnium tetrachloride, characterized by, Includes the following steps: Step 1: Add hafnium tetrachloride to the sublimation equipment under a protective gas atmosphere, and collect the product fraction under low vacuum. The sublimation temperature is 240-280℃; the high boiling point temperature is 200-230℃, the product temperature is 130-160℃, and the low boiling point temperature is 50-110℃. Step 2: Sample the product fraction collected in Step 1 in the back-end glove box and repeat the above operation for multiple sublimation to finally obtain high-purity hafnium tetrachloride product.

2. The method according to claim 1, wherein the method is characterized by, Step 1 involves adding hafnium tetrachloride to the sublimation equipment in the front glove box, and Step 2 involves sampling in the rear glove box under the protection of a protective gas.

3. The method according to claim 2, wherein the method is characterized by, The sublimation device is provided with a sublimation end and a receiving end, and a filter and an electromagnetic vibrator are installed between the sublimation end and the receiving end.

4. The method according to claim 3, wherein the method is characterized by, The filter material is molybdenum or tantalum, and the mesh size is ≥800 mesh.

5. The method for preparing small-particle-size high-purity hafnium tetrachloride according to claim 3, characterized in that, The electromagnetic vibrator has a vibration frequency of 500-2000 times per minute.

6. The method for preparing small-particle-size high-purity hafnium tetrachloride according to claim 2, characterized in that, The water and oxygen levels in the front and rear glove boxes are <0.1 ppm.

7. The method for preparing small-particle-size high-purity hafnium tetrachloride according to claim 1, characterized in that, The raw material, hafnium tetrachloride, is in powder form with a purity of not less than 99%.

8. The method for preparing small-particle-size high-purity hafnium tetrachloride according to claim 1, characterized in that, The sublimation in step 1 is performed under low vacuum conditions, with a vacuum level of 100-150 Pa.

9. The method for preparing small-particle-size high-purity hafnium tetrachloride according to claim 1, characterized in that, The protective gas is one of nitrogen, argon, or helium.

10. The method for preparing small-particle-size high-purity hafnium tetrachloride according to claim 1, characterized in that, In step 2, the sublimation process is repeated 2-4 times. The purity of the high-purity hafnium tetrachloride product is not less than 99.999%, and the particle size of the product is 78.3μm-91.5μm.