1、Designation: F1761 00 (Reapproved 2011)Standard Test Method forPass Through Flux of Circular Magnetic Sputtering Targets1This standard is issued under the fixed designation F1761; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers measuring the dc magnetic fieldtransmitted through a ferromagnetic sputtering target
3、(“passthrough flux” or “PTF”). In this test method the sourcemagnetic field is in the test targets circumferential direction.1.2 Planar disk-shaped targets in the diameter range 5 to 8in. inclusive (125 to 205 mm inclusive) and of thickness 0.1 to0.5 in. inclusive (2.5 to 13 mm) may be characterized
4、 by thisprocedure.1.3 This test method is also applicable to targets having anopen center, for example, to targets 5-in. outside diameter by2.5-in. inside diameter by 0.25-in. thick (127-mm outsidediameter by 63.5-mm inside diameter by 6.35-mm thick).1.4 Targets of various diameters and thicknesses
5、are accom-modated by suitable fixturing to align the piece under test withthe source magnet mounted in the test fixture. Tooling, cover-ing several popular target designs is specified in this procedure.Additional target configurations may be tested by providingspecial tooling. When special fixturing
6、 is used all partiesconcerned with the testing must agree to the test setup.1.5 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.6 This
7、standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Defini
8、tions:2.1.1 pass through flux (PTF), (n)For purposes of thisstandard the “pass through flux” is the dc magnetic fieldtransmitted through a ferromagnetic sputtering target, from oneface to the opposite face.2.1.1.1 DiscussionPTF is also frequently called “leakageflux.”2.1.2 reference field, nFor purp
9、oses of this standard the“reference field” is the dc magnetic field measured with theHall probe Gaussmeter when no sputtering target is in positionon the test stand. The strength of the reference field dependsupon the height and position of the Hall probe relative to thesource magnet.2.1.3 source fi
10、eld, nFor purposes of this standard the“source field” is the dc magnetic field measured with the Hallprobe at the top surface of the target support table.3. Summary of Test Method3.1 The sputtering target under test is mounted on a testfixture in which a permanent horseshoe-shaped magnet is heldin p
11、roximity to one of the flat planar faces of the target. A Hallprobe Gaussmeter is used to measure the dc magnetic fieldpenetrating the target and entering the air space from targetsopposite face.4. Significance and Use4.1 It is standard practice to use magnetron cathode sputterdeposition sources in
12、manufacturing thin film magnetic datastorage media. But a ferromagnetic sputtering target tends toshunt a sputtering cathodes magnetic field, thus reducing theefficiency of the sputtering process.4.2 Makers of sputtering targets have developed variousmeans of controlling alloy microstructure to mini
13、mize theundesirable cathode shunting effect. Because of their differingmanufacturing methods, however, the targets of one suppliermay have magnetic properties significantly better or worse thanthose of another, even when the alloy compositions are thesame.4.3 This test method permits comparing the m
14、agnetic shunt-ing power of magnetic targets under a standard test condition.The results are useful to sputtering target suppliers and buyersin predicting target performance, in specifying target quality,and in qualifying incoming target shipments. This test may alsobe useful in quantifying target im
15、provement efforts.4.4 Manufacturing process steps that lower a target materi-als magnetic permeability tend to increase the PTF, and viceversa. It would in principle be possible to predict the PTF byaccumulating sufficient permeability data, and knowing the1This test method is under the jurisdiction
16、 of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.17 on SputterMetallization.Current edition approved June 1, 2011. Published June 2011. Originallyapproved in 1996. Last previous edition approved in 2005 as F1761 00 (05). DOI:10.1520/F1761-00R11.1Copyright AST
17、M International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.target thickness and the field intensity of the magnetic assem-bly used for magnetron sputtering.5. Interferences5.1 The magnetic test fixture must be located in an area freeof extraneous ferromagnet
18、ic materials and strong magneticfields that would interfere with the source magnettest speci-men dc magnetic-field configuration.5.2 The “magnetic conditioning” effect is strong in somesputtering target alloys. It is important to verify that the targetunder test is magnetically stabilized before fin
19、alizing a data set(see 9.2).6. Apparatus6.1 This method requires the use of a special test fixture. Itsconstruction is specified in Appendix X1.6.2 Gaussmeter, is required, equipped with a portabletransverse-field Hall probe blade nominally 0.040-in. thick by0.170-in. wide by 2.5-in. long (1.0-mm by
20、 4.3-mm by 64 mm).The Gaussmeter must be capable of measuring dc magneticfields in the range 10 Gauss to 3500 Gauss, inclusive, to anaccuracy of 62 %. This unit is designated the “measuringGaussmeter,” and is used for making the magnetic fieldmeasurements specified in this test method.6.2.1 It is im
21、portant that the semiconductor Hall probesensing element be mounted at the extreme tip end of theprobe. The distance from the probe tip to the center of thesensing element must not exceed 0.030 in. (0.75 mm).6.3 It is convenient to have a second Gaussmeter available,also equipped with a portable tra
22、nsverse-field Hall probe blade.This unit must be capable of measuring dc magnetic fields inthe range 1 Gauss to 50 Gauss, inclusive, to an accuracy of620 %. This unit is referred to in 8.1 as the “screeningGaussmeter.” It is used to monitor residual magnetic fields intest specimen sputtering targets
23、.NOTE 1If a “screening Gaussmeter” is not available, the targets undertest must be degaussed and verified (8.3) using the measuring Gaussmeter,before starting Section 7.6.4 Demagnetizer2, is needed that is capable of removingthe remnant magnetization in sputtering targets to be tested.7. Preparation
24、 of Apparatus7.1 Verify that the source magnet is securely clamped withits vertical center plane located 5.750 6 0.015 in. (146.1 6 0.4mm) from the end of the baseplate. This is illustrated in Fig. 1.7.2 Verify that the pole faces of the source magnet are inlight contact with the bottom of the targe
25、t support table.Adjustment of the magnets vertical position can be made byloosening the magnet clamp screws, inserting nonmagneticshims under the magnet, and retightening the clamp screws.Recheck magnet location, in accordance with 7.1, if shims areadjusted.7.3 Activate, zero, and calibrate the meas
26、uring Gaussmeter(6.2) using the manufacturers instructions.7.4 Mount the Gaussmeter probe in the fixtures Hall probesupport tube. The bottom tip of the probe should extend 0.0506 0.025 in. (1.25 6 0.64 mm) beyond the support tube.Mounted properly, the probe tip will be clearly visible, stickingout o
27、f its support. Gently tighten the nylon clamping screws tosecure and center the Hall probe blade in position in the probesupport tube. Excessive tightening may result in damage to theprobe that can affect test results.7.5 By visual sighting, align the Hall probe as indicated inFig. 1, but with the p
28、robe tip close to but not touching the targetsupport table. The Hall probe should be roughly centeredbetween the magnet poles, and the flats of the probe bladeshould be parallel to the fixtures long dimension. Note that theouter vertical edge of the probe blade is aligned with the sideof the magnet,
29、 illustrated in Fig. 1. Loosen the post attachmentscrew at the baseplate and adjust the Hall probe post position,if necessary, to achieve the correct location.7.5.1 To make the adjustments indicated in this and subse-quent paragraphs, it may be necessary to loosen and retightenthe collars on the Hal
30、l probe support post and the appropriatenylon clamping screws, which secure other parts of theapparatus.7.6 Lower the support arm until the Hall probe blade tip isin bare (light) contact with the target support table. Note theGaussmeter reading. Swing (rotate) the cross arm to center theprobe blade
31、between the magnetic poles, and slightly rotate theprobe support tube, as necessary, to maximize the Gaussmeterreadings. The proper position is achieved when the Gaussmeterreading indicates a clear maximum in the magnetic fieldstrength.NOTE 2If a clear maximum cannot be identified, the Hall probe bl
32、adeis not adequately centered in the probe support tube (see 7.4), or the bladeis not in correct transverse alignment (7.6), Repeat 7.4 or 7.6 as required,to provide a discernible maximum point in 7.6.7.6.1 The maximum Gaussmeter reading at the target sup-port table (7.6) is the “source field” (2.1.
33、3).NOTE 3Measuring and recording (preferably using an SPC controlchart) the source field provides important information about the stabilityof the measuring system. A significant deviation in source field strengthmay indicate a problem with the Hall probe, or a change in the operatingenvironment that
34、 may influence the test results.7.7 The source field (7.6.1) must be in the range 825 6 50Gauss.7.7.1 If the dc magnetic field is not in the required range(7.7) the Hall probe should be inspected and replaced if anyevidence of damage is observed. If there are no indications ofprobe damage the measur
35、ement of the source field (7.2-7.6)should be repeated, as needed, until the requirement of 7.7 issatisfied.7.8 Lift the probe support cross arm to a position in whichthe clearance between Hall probe tip and the top surface of thetarget to be tested (with the TFE-fluorocarbon washer in place),will be
36、 0.075 6 0.025 in. (2.0 6 0.6 mm). Adjust and tightenthe collars on the probe support post to maintain the probesupport cross arm at this elevation.2The sole source of supply of the demagnetizer, 60-Hz hand held coil known tothe committee at this time is Realistic High Power Video/Audio Tape Eraser,
37、 catalognumber 44-233Afrom Radio Shack. If you are aware of alternative suppliers, pleaseprovide this information to ASTM Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.F1761 00 (2011)27.9 Swing (rotate) the prob
38、e support arm as in 7.6 tomaximize the Gaussmeter reading. Record this value.7.9.1 The maximum dc magnetic field reading, with the Hallprobe in the test position but with no sputtering target in placeon the fixtures table, is the “reference field” (2.1.2).7.10 Swing the cross arm to move the probe c
39、lear of thetarget support table.7.11 Place the TFE-fluorocarbon washer in position on thetarget support table. The test fixture is now ready for use.8. Target Preparation8.1 Activate, zero, and calibrate the screening Gaussmeter(6.3) according to the manufacturers instructions.8.2 Use the Gaussmeter
40、 to determine that the stray magneticfield in the immediate work area is less than 1 Gauss instrength. Remove sources of excessive stray fields, if neces-sary.8.3 Measure the residual magnetic field in the test target byscanning the Gaussmeter probe lightly over the target surface,noting the magneti
41、c intensity component perpendicular to thesurface.8.4 If the residual field exceeds 3 Gauss at any point, treatthe test target with the demagnetizer (6.4) until the residualfield is reduced to less than 3 Gauss.9. Procedure9.1 Identify and mark (for example, with a tab of adhesivetape) a fiducial “z
42、ero” position on the outer rim of sputteringtarget under test.9.2 Mount the test target on the target table of the PTFfixture. Magnetically condition the target by rotating it coun-terclockwise on the target support table five complete turns. Itis important for reproducible results that the target r
43、otation isalways in the same direction, for example, counterclockwise.FIG. 1 PTF Test Fixture Setup Schematic DrawingF1761 00 (2011)3NOTE 4Some magnetic conditioning is usually required to achievestable, repeatable, PTF values. For most alloys, five magnetic cycles(turns) is adequate. In some except
44、ional cases more cycles may berequired (see 9.10).9.3 By rotating the target counterclockwise align the zeromark with the Hall probe support post.9.4 Swing the Hall probe into position over the target usingcare to ensure that the height of the probe above the targetsurface is not changed from its or
45、iginal setting (7.8).9.5 Note the Gaussmeter reading. Swing (rotate) the crossarm to locate the position of maximum magnetic field value.Tighten the nylon friction screw to secure the probe in thisposition.9.6 Record the Gaussmeter magnetic field value at this“zero degrees” target orientation.9.7 Ro
46、tate the target 30 6 5 counterclockwise and recordthe magnetic field value at the “30” target orientation.9.8 Repeat 9.7 at 60, 90, and 120 target orientations.Record the Gaussmeter readings at each angular setting.9.8.1 Use caution to avoid bumping moving the Hall probewhile manipulating the target
47、 orientation. If the probe is movedit is necessary to start over again, repeating 9.2-9.8.9.9 Without changing the probe height swing (rotate) thecross arm so that the target may be removed without bumpingthe probe. Remove the target.9.10 For the first few targets (typically, three test pieces) ofa
48、new alloy or new type, verify that the magnetic conditioning(9.2) is adequate by remounting the test target(s) and repeating9.2-9.9. The PTF values measured the second time shouldagree within 5 % of those determined in the first pass. If thePTF values do not reproduce within the required precision,r
49、epeat the magnetic conditioning (9.2) sufficient times so thatstability is achieved. Future tests of this particular target typewill require the more rigorous preconditioning.NOTE 5It is sound practice to degauss the test target after themeasuring procedure is complete.10. Computations10.1 For each of the five individual PTF readings (Section9), divide by the reference dc magnetic field (7.9) and multiplythis quotient by 100 to compute the percentage of the dcmagnetic field transmitted through the target (% PTF).10.2 Review the data to identify the maximum and
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