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Preparation Method Of Niobium Tubular Target Materials For Sputtering
Oct 11, 2018

Technical field


The invention belongs to the technical field of Nb sputtering target manufacturing, and in particular relates to a method for preparing a tubular bismuth target for magnetron sputtering.


Background technique


Prior to 2008, magnetron sputtering used all of the plate targets, that is, the target was a rectangular plate having a certain thickness as seen from the shape. One of the biggest drawbacks of such targets is that the material utilization rate is only 25% to 30%.


The use of tubular targets is of particular importance to the coating industry. By assembling a controllable magnet in a seamless pipe (tubular target) of a certain size, the surface of the sputtering target can be free from dead angles, and the surface self-consumption process is relatively uniform, which can increase the material utilization rate to 70. % or even higher, even if the manufacturing cost of the tubular target itself is increased, it is more than one-third lower than the cost of the plate target. At present, the coating of rare metal niobium (Nb1) has high cost performance in heat insulation, conduction, ultraviolet blocking and permeability, so metal niobium (Nb1) is one of the main materials for manufacturing targets.


At present, the main preparation methods of the tubular target and part of the non-ferrous metal tubular target are casting method, sheet coiling, centrifugal casting, plating on the support tube or thermal spraying of the target material to form the target. Generally, the ruthenium target particles prepared by the casting method are coarse, the tube target strength is low, the subsequent processing steps required are complicated, and the film formation rate is low; although the enamel sheet coil tube welding is simple in process and high in yield, the method is due to the weld seam. Existence, resulting in uneven structure of the target structure of the fistula, will have a serious impact on the uniformity of the coating; centrifugal casting method belongs to the near forming technology, the method is simple, the subsequent processing is less, but the equipment requirements are high, it is difficult to produce large-sized fistula target and carry out Large-scale industrial production; the method of electroplating or thermal spraying of base metal on the support tube is difficult to prepare a thick-walled tube target, and the wall thickness of the tube target is an important factor for improving the utilization rate of the target.


A method for preparing a tantalum tubular target for sputtering is disclosed in the invention patent of the publication No. CN 102489951 A, which is incorporated herein by reference. The purpose is to protect the tube blank from oxidation, but the sleeve is easy to cause uneven deformation and sag in the range of about 400mm at the outlet end of the tube during the extrusion process. The outer diameter of the tubular target is severe. The effect is even scrapped; at the same time, the covering material is difficult to remove in the subsequent process, which seriously affects the purity of the processing debris of the crucible to generate waste. In addition, the method firstly performs vacuum heat treatment on the extruded fistula target, and then performs mechanical processing. The strength and hardness of the pure metal crucible after vacuum heat treatment are reduced, and the dimensional accuracy and surface smoothness of the tubular target are not easily ensured during mechanical processing.


Summary of the invention


The technical problem to be solved by the present invention is to provide a method for preparing a tubular ruthenium target for magnetron sputtering with simple process flow and high production efficiency in view of the above-mentioned deficiencies of the prior art. The tubular bismuth target prepared by the method has good microstructure, uniform grain along the wall thickness direction of the target, grain size grade 4-6, grain size not more than 100 μm, recrystallization rate not less than 90%, and magnetic proof Control the uniformity of the coating during sputtering.


In order to solve the above technical problem, the technical solution adopted by the present invention is: a method for preparing a tubular bismuth target for magnetron sputtering, characterized in that the method comprises the following steps:


Step 1. Forging a barium ingot having a diameter of 220 mm to 260 mm at a temperature of 1000 ° C to 1200 ° C to form a cylindrical crucible having a diameter of 265 mm to 275 mm;


Step 2: drilling a through hole having a diameter of 49 mm to 51 mm in the center of the cylindrical crucible in the first step to obtain a tubular crucible, and then uniformly coating an anti-oxidation coating on the inner and outer walls of the tubular crucible. Preventing oxidation of the surface of the tubular niobium during subsequent extrusion;


Step 3: The tubular ruthenium material coated with the anti-oxidation coating in the second step is extruded at an extrusion temperature of 900 ° C to 1050 ° C and an extrusion ratio of 4.1 to 7.6 to an outer diameter of 140 mm to 170 mm. a tube billet of 100 mm to 135 mm; controlling the extrusion speed during the pressing process is 150 mm/s to 180 mm/s;


Step 4: sequentially blasting, pickling and mechanically processing the tube blank in the third step to obtain a semi-finished product of a tubular target having an outer diameter of 135 mm to 165 mm and an inner diameter of 105 mm to 140 mm;


Step 5: performing vacuum heat treatment on the tubular bismuth target semi-finished product in the fourth step to obtain a tubular bismuth target for magnetron sputtering; the vacuum heat treatment treatment temperature is 930 ° C to 1080 ° C, and the heat preservation time is 100 min to 300 min.


In the above method for preparing a tubular ruthenium target for magnetron sputtering, in the first step, the ruthenium ingot is an Nb1 ingot prepared by electron beam melting.


In the above method for preparing a tubular ruthenium target for magnetron sputtering, the direction of extension of the tubular ruthenium in the extrusion process in the third step is always along the axial direction of the 铌 tubular 铌 blank.


The present invention has the following advantages over the prior art:


1. The process of the invention is simple and reasonable, and the production efficiency is high.


2. The invention can perform preliminary crushing of bismuth grains with a macroscopic size of about 100 mm by high-temperature forging of bismuth ingots to form a certain number of subgrain boundaries; using an extrusion ratio of 4.1 to 7.6, combined with 150 mm/s The extrusion speed of ~180 mm/s makes the microstructure containing the subgrain boundary in the previous stage further become a uniform fine structure after processing, and the fine structure can be retained without dynamic recrystallization due to the cooling of the tube wall.


3. The invention adopts an anti-oxidation coating to protect the inner and outer wall surfaces of the tubular slab blank, and the anti-oxidation coating belongs to a common borosilicate glass protective lubricating coating, which has the protection and lubricating effect during extrusion, and subsequent processing. The anti-oxidation coating has a natural collapse feature, which avoids the defect of uneven size of the blank produced by the use of the covering material and eliminates the defects of mechanical processing to remove the contamination of the residual material by the wrapping material.


4. The present invention performs the blasting, pickling and mechanical processing on the extruded bismuth tube blank, and then vacuum heat treatment to ensure the dimensional accuracy and surface quality of the tubular bismuth target product, and at the same time ensure the tubular bismuth target. The tissue performance characteristics of the finished product.


5. The invention maintains the axial direction of the original ingot by controlling the direction of the blank in the extrusion process, and the vacuum heat treatment of the appropriate system ensures the uniformity of the grain in the longitudinal direction of the tubular target.


6. The tubular bismuth target prepared by the method of the invention has good microstructure, uniform grain along the wall thickness direction of the target, grain size grade 4-6, grain size not more than 100 μm, recrystallization rate not less than 90% It ensures the uniformity of the coating during magnetron sputtering.


The technical solution of the present invention will be further described in detail below by way of embodiments.


detailed description


Example 1


Step 1. The Nb1 ingot prepared by electron beam melting and having a diameter of 220 mm and a length of 602 mm is forged into a cylindrical crucible having a diameter of 270 mm at a temperature of 1200 ° C;


Step 2: drilling a through hole having a diameter of 50 mm in the center of the cylindrical crucible in the first step to obtain a tubular crucible, and then uniformly coating the inner and outer surfaces of the tubular crucible with an anti-oxidation coating (can be used conventionally) Glass protective lubricants, such as the glass protective lubricant TLC-8 of Beijing Tianli Chuang Glass Technology Development Co., Ltd., to prevent oxidation of the surface of the tubular niobium in the subsequent extrusion process;


Step 3: The tubular tantalum blank coated with the anti-oxidation coating in the second step is extruded into a tantalum billet having an outer diameter of 170 mm and an inner diameter of 125 mm under the conditions of an extrusion temperature of 900 ° C and an extrusion ratio of 4.1; The extrusion speed is controlled to be 180 mm/s during the extrusion process; the extension direction of the tubular concrete blank during the extrusion process is always along the axial direction of the original tantalum ingot;


Step 4: sequentially blasting, pickling and mechanically processing the tube blank in the third step to obtain a semi-finished product of a tubular target having an outer diameter of 165 mm and an inner diameter of 130 mm;


Step 5: performing vacuum heat treatment on the tubular bismuth target semi-finished product in the fourth step to obtain a finished tubular bismuth target for magnetron sputtering; the vacuum heat treatment treatment temperature is 930 ° C, and the heat preservation time is 300 min.


In this embodiment, by performing high-temperature forging on the bismuth ingot, the ruthenium grains with a macroscopic size of about 100 mm can be initially crushed to form a certain number of subgrain boundaries; the extrusion ratio of 4.1 is combined with the extrusion of 180 mm/s. The velocity causes the microstructure that already contains the subgrain boundary to further become a uniform fine microstructure after processing, and the fine tissue can be retained due to the temperature reduction of the tube wall without dynamic recrystallization; by controlling the elongation of the blank during the extrusion process The direction is always the axial direction of the original ingot, combined with the appropriate system of vacuum heat treatment, to ensure the uniformity of the grain length of the tubular bismuth target; the prepared tubular 铌 target has good microstructure and the grain along the wall thickness direction of the target Uniform, grain size grade 4.5, grain size 80μm, recrystallization rate greater than 95%, to ensure uniformity of coating during magnetron sputtering.


Example 2


Step 1. The Nb1 ingot prepared by electron beam melting and having a diameter of 260 mm and a length of 560 mm is forged into a cylindrical crucible having a diameter of 275 mm at a temperature of 1000 ° C;


Step 2: drilling a through-hole having a diameter of 49 mm in the center of the cylindrical crucible in the first step to obtain a tubular crucible, and then uniformly coating the inner and outer surfaces of the tubular crucible with an anti-oxidation coating (can be conventionally used) Glass protective lubricants, such as the glass protective lubricant FR-35 produced by Beijing Glass Research Institute, to prevent oxidation of the surface of the tubular concrete during subsequent extrusion;


Step 3: The tubular tantalum blank coated with the anti-oxidation coating in the second step is extruded into a concrete tube having an outer diameter of 140 mm and an inner diameter of 100 mm under the conditions of an extrusion temperature of 1050 ° C and an extrusion ratio of 6.6; The extrusion speed is controlled to be 150 mm/s during the extrusion process; the extension direction of the tubular concrete blank during the extrusion process is always along the axial direction of the original tantalum ingot;


Step 4: sequentially blasting, pickling and mechanically processing the tube blank in the third step to obtain a semi-finished product of a tubular target having an outer diameter of 135 mm and an inner diameter of 105 mm;


Step 5: performing vacuum heat treatment on the tubular bismuth target semi-finished product in the fourth step to obtain a finished tubular bismuth target for magnetron sputtering; the vacuum heat treatment treatment temperature is 1080 ° C, and the heat preservation time is 100 min.


In this embodiment, the high-temperature forging of the bismuth ingot can be used to initially crush the ruthenium grains with a macroscopic size of about 100 mm to form a certain number of subgrain boundaries; the extrusion ratio of 6.6 is combined with the extrusion of 150 mm/s. The velocity causes the microstructure that already contains the subgrain boundary to further become a uniform fine microstructure after processing, and the fine tissue can be retained due to the temperature reduction of the tube wall without dynamic recrystallization; by controlling the elongation of the blank during the extrusion process The direction is always the axial direction of the original ingot, combined with the appropriate system of vacuum heat treatment, to ensure the uniformity of the grain length of the tubular bismuth target; the prepared tubular 铌 target has good microstructure and the grain along the wall thickness direction of the target Uniform, grain size grade 5.5, grain size 60μm, recrystallization rate greater than 95%, to ensure uniformity of coating during magnetron sputtering.


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