RU2763719C1 - Method for manufacturing cathodes for magnetron sputtering installations made of refractory metals - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to the field of mechanical engineering, in particular to the processing and manufacture of parts. The method includes electroerosive processing of the workpiece in the form of a rod on a wire-cutting machine with numerical control (CNC), which ensures dimensional accuracy, taking into account allowances for subsequent machining, in which a disk is cut off from the rod. After electroerosion treatment, the resulting disk is finished by sequentially removing the allowance from 0.007 to 0.015 mm on a CNC lathe in two installations on each side, ensuring a surface roughness of Ra 0.4 mm and the absence of a defective layer on the cathode surface.

EFFECT: invention provides the production of cathodes from refractory metals for magnetron sputtering installations with the required parameters of chemical composition and surface roughness while minimizing waste.

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Description

The invention relates to the field of mechanical engineering, in particular to the processing and manufacture of parts of the "disk" type.

It is known to remove the metal of the workpiece by electroerosive machining in a dielectric medium due to microdischarges that melt part of the metal [Artamonov B. A., Volkov Yu.S., Drozhalova V.I. and others: "Electrophysical and electrochemical methods of material processing". Proc. allowance (in 2 volumes), vol. 1: "Processing of materials using tools" / Ed. V.P. Smolentsev. M.: Higher. Shk., 1983. 247 p. Part 1, p. 7].

The disadvantage of this method is the introduction into the surface layer of the electrode-tool material, as well as the occurrence of various phases obtained from the materials of the workpiece and the electrode-tool, due to short-term high-temperature exposure to the workpiece and subsequent rapid cooling, which is unacceptable in the manufacture of targets (cathodes) for installations magnetron sputtering.

Known electrochemical processing of materials that are difficult to blade processing methods ["Method of bilateral electrochemical dimensional processing of parts", EN 2473412 C2 (ALEKSANDROV A.P. and others), 27.01.2013]. This method allows you to simultaneously remove the same allowances from both sides. Also known is a method for processing products using a combination of two well-known methods: electroerosive machining and subsequent electrochemical polishing [“Method of manufacturing a gear wheel” RU 2586936 C1 (FEDERAL STATE BUDGETARY EDUCATIONAL INSTITUTION OF HIGHER PROFESSIONAL EDUCATION "OMSK STATE TECHNICAL UNIVERSITY"), 10.06.2 .

The disadvantage of these methods is the insufficient removal of the surface layer containing particles of the electrode-tool material, as well as the uneven removal of the surface layer, which is unacceptable in the manufacture of cathodes for magnetron sputtering installations.

Known methods for the manufacture of cathodes, which use the melting and casting of cathodes using various additional actions (rotation, vibration, pre-treatment of the recess in the cathode and pouring the melt) "Method of manufacturing a target for sputtering in vacuum" SU 1494559 publ. 03/10/1996, "Method of obtaining silicon targets for magnetron sputtering" RU 2635209 publ. 11/09/2017, "Method of manufacturing a sputtered target of a magnetron source for coating" RU 2567783 publ. 11/10/2015.

The disadvantage of these methods is the low productivity of manufacturing cathodes (targets). For refractory materials, there is a rolled section (rod) with a ground surface of a high percentage (99.995%) of the material deposited on the surface during magnetron sputtering. Such blanks can be used immediately after being cut into cathodes, if a diffusion layer does not appear on the surface during processing.

A known method of manufacturing shaped targets (cathodes) from refractory materials and their alloys (tantalum, niobium) for magnetron sputtering ("HOLLOW CATHODE TARGET AND METHODS FOR ITS MANUFACTURE" US 6113761 A1 (KARDOK US), 05.09.2000).

The disadvantage of this method is the complicated technology for obtaining targets, then cathodes, in which it is necessary to perform transverse rolling of the workpiece and cold work the rolled workpiece, as well as the need for heat treatment and mechanical cleaning between the stages of rolling and cold working, which leads to low cathode manufacturing productivity.

The objective of the invention is to reduce waste in the processing of rare and, as a result, expensive, refractory metals in the manufacture of cathodes for magnetron sputtering installations.

This technical result is achieved by the fact that the processing is carried out in a combined way, at the first stage - non-mechanical (electroerosive), and at the second stage - mechanical (fine turning). First, electroerosive machining is performed in an electric spark or electric pulse mode with a non-profiled tool (wire), during this processing, a disk of the same diameter (40-50 mm) and a thickness of 6-12 mm is cut from a cylindrical bar with a diameter of 40 to 50 mm. Next, fine turning is carried out on turning equipment for two setups on each side, to eliminate the defective layer remaining after electroerosive machining and achieve the required surface quality.

A method for manufacturing cathodes for magnetron sputtering installations from refractory metals, including electroerosive processing of a workpiece in the form of a rod on a wire-cut machine with numerical control (CNC), which ensures dimensional accuracy, taking into account allowances for subsequent machining, in which a disk is cut from the rod, according to according to the claimed technical solution, after electroerosive machining, the resulting disk is finished turning by sequentially removing the allowance from 0.007 to 0.015 mm on a CNC lathe in two settings on each side to ensure a surface roughness of Ra 0.4 μm and the absence of a defective layer on the cathode surface.

Let us consider a method for manufacturing cathodes for magnetron sputtering installations from refractory metals using a specific example. Electroerosive processing of the workpiece is carried out on a wire-cutting machine with numerical control (CNC), providing dimensions when processing cathodes with a thickness of 6 mm - from 6.04 to 6.1 mm, when processing cathodes with a thickness of 12 mm - from 12.04 to 12.1, taking into account allowances for subsequent machining, and then the resulting disc is machined, in which the disc is mounted in a three-jaw self-centering chuck and machined from both sides. The disc is mounted on the table of the wire-cutting machine using a prism. According to the drawing of the cathode, the processing trajectory is set with an offset from the measuring base. A numerical control (CNC) programming system, such as Heart NC UTY The CNC generates (determines) processing modes: pulse length, pause length between pulses, basic current, spark gap voltage, generator power supply voltage, upper processing speed limit, value wire tension, wire winding speed. Next, the processing program is started in the CNC device and a cut is made in the forward direction, perpendicular to the axis of the disk, using electric sparks flowing through the wire, obtaining the required profile. Next, the resulting disk is installed in a three-jaw self-centering chuck and processed on a CNC lathe for subsequent removal of the defective layer. One side is processed in the following modes: cutting speed (V) - 61–91 m / min, cutting tool feed (S) - 0.03 mm / rev, tool cutting edge radius (r) - 0.2 mm). After that, the disk is turned over and processed in the same modes on the other side. After electroerosive machining, the resulting disk is finished turning by sequentially removing the allowance from 0.007 to 0.015 mm on a CNC lathe in two settings on each side to ensure surface roughness Ra 0.4 mm and the absence of a defective layer on the cathode surface.

On FIG. 1 shows the table of the electroerosive machine SODICKVZ300L with a prism fixed on it, in which the workpiece is installed.

Fig. 2 Fig. 8 display photographs and illustrations that are presented as a supplement to the graphics.

On FIG. 2 shows the menu of the function of automatic rotation of the coordinate system ("ROV AUTO SC") in the "MANUAL" mode.

On FIG. 3 shows the function menu for determining zero coordinates (along the X and Y axes) in the "MANUAL" mode.

On FIG. 4 shows the selection of the wire path in the "WIRECUTDEFS" menu.

On FIG. 5 shows the table for defining the parameters "DEFINITION PARAMETERS"

On FIG. 6 shows a table for selecting processing modes on the screen.

On FIG. 7 shows discs of different metals cut from bars.

On FIG. 8 shows the scheme of cathode processing on turning equipment in a three-jaw self-centering chuck for turning: 1) cathode; 2) three-jaw self-centering chuck; 3) cutter.

Consider a specific example of the implementation of the processing of workpieces in the process of manufacturing cathodes for magnetron sputtering installations (Fig. 1).

The workpiece 1 is installed in the prism 2, fixed on the table 3 wire-cutting machine, such as SODICKVZ 300L. Using clamp 4 and screw 5, the workpiece is fixed in prism 2, which in turn is already fixed with clamp 4 and screw 5 on table 3. The position of workpiece 1 on table 3 of the machine is determined. Processing is carried out using a wire electrode 6 (Fig. 1). In order not to align the workpiece on the machine table with an indicator, it is necessary to expand the coordinate system along the end. To do this, in the "MANUAL" mode, select the function of automatic rotation of the coordinates "REVOLVE SC AUTO" (Fig. 2). In the ST DIRECTION field, specify the direction in which the wire should touch the workpiece. In our case, X+. In the "DISTANCE TO OTHER POINTS" field, specify the maximum distant point (for example, 40 mm with a workpiece diameter of 50 mm). After pressing the "ENTER" key, the machine automatically expands the coordinate system along the edge of the workpiece. Further, the "local" origin of coordinates for a given position of the workpiece relative to the machine coordinate system. To do this, in the "MANUAL" mode, select the "FACE TOUCH" function, first along the X axis (Fig. 3). After touching the end of the workpiece with the wire, assign this surface 0 along the X axis. After that, do the same for the Y axis, touching the round surface. Next, set the trajectory of the wire (Fig. 4) according to the drawing of the part, leaving the allowance for subsequent grinding in the menu "WIRECUTDEFS" select the type of trajectory processing "OPEN" (open). In this case, the parameter definition table "DEFINITION PARAMETERS" appears (Fig. 5). In the table, set the length of the starting cut "Starting Cut Length" 5 mm. At the starting cut, the machine lowers the processing modes to reduce the likelihood of wire breakage. Confirm the selected parameters with the OK button (Fig. 5). An image of the mode selection table appears on the monitor (Fig. 6). In it, set the diameter of the wire that is installed on the machine. In a specific implementation example, 0.20 mm, the workpiece material is zirconium, the workpiece thickness is 50 mm, the position of the nozzle is "OPEN", the number of passes is 1. We confirm the selected parameters with the "SEARCH" button. We indicate with the cursor the contour along which the tool will move, and set the starting point, from which we cut the workpiece with electric spark discharges flowing through the wire. Press the "Gen NC Data" button. After that, we type the name of the program: for example, "KATOD", under which it will be stored on the hard drive. The CNC automatically generates the program and determines the optimal cutting conditions: pulse length (ON), pause length between pulses (OFF), basic current (IP), spark gap voltage (SV), generator power supply voltage (V), upper speed limit processing (SF), wire tension value (WT), wire winding speed (WS), based on the entered data. According to the generated program, the workpiece is cut with electric sparks flowing through the wire and a finished disk is obtained. Next, we install the resulting disk in a three-jaw self-centering chuck along the end and cylinder (Fig. 8) and onto a lathe. Then we perform machining (with calculated modes, based on the material of the workpiece, for refractory materials, the cutting speed (V) is 61–91 m/min, the cutting tool feed (S) is 0.03 mm/rev, the radius of the cutting edge of the tool (r ) - 0.2 mm), in our case, with a grain size of 30 microns and a workpiece material - zirconium alloy E-110, the processing time of one side is 20 sec. After that, the disk must be turned over and processed to ensure uniform metal removal. Consistent application of these machining methods provides productivity that is independent of the mechanical properties of the material, such as, for example, hardness and toughness, due to which higher workability is achieved in the processing of products in the process of manufacturing cathodes for magnetron sputtering installations from refractory metals, in comparison with machining products.

Such a manufacturing method can be used to manufacture cathodes for magnetron sputtering installations from rare and, as a result, expensive metals, since waste during processing is minimal.

Claims (1)

A method for manufacturing cathodes from refractory metals for magnetron sputtering installations, which includes electroerosive processing of a workpiece in the form of a rod on a wire-cut machine with numerical control (CNC), which ensures dimensional accuracy, taking into account allowances for subsequent machining, in which a disk is cut from the rod, which differs the fact that after electroerosive machining, the resulting disk is finished turning by sequentially removing the allowance from 0.007 to 0.015 mm on a CNC lathe in two settings on each side to ensure surface roughness Ra 0.4 mm and the absence of a defective layer on the cathode surface.

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