Inexpensive, flexible sample transfer systemQibiao Chen, P. Chevako, and M. Onellion Citation: Review of Scientific Instruments 62, 244 (1991); doi: 10.1063/1.1142323 View online: http://dx.doi.org/10.1063/1.1142323 View Table of Contents: http://scitation.aip.org/content/aip/journal/rsi/62/1?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Development of a multitask and multiinstrument sample transfer system J. Vac. Sci. Technol. B 13, 1900 (1995); 10.1116/1.587832 A flexible sample transfer/insertion system for ultrahigh vacuum surface studies J. Vac. Sci. Technol. A 5, 2970 (1987); 10.1116/1.574234 An inexpensive heatable sample assembly and transfer mechanism J. Vac. Sci. Technol. A 2, 1396 (1984); 10.1116/1.572375 Versatile UHV sample transfer system J. Vac. Sci. Technol. 16, 708 (1979); 10.1116/1.570063 System for transferring samples between chambers in UHV J. Vac. Sci. Technol. 15, 1756 (1978); 10.1116/1.569840

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Inexpensive, flexible sample transfer system Qibiao Chen, P. Chewako, and M. Onellion”) Physics Department, University of Wisconsin, Madison, Wisconsin 53 706

(Received 25 July 1990; accepted for publication 16 September 1990)

A simple, inexpensive, and flexible sample transfer system is described. The system possesses the advantages of excellent base pressure and the flexibility to study thin films deposited in situ. We have applied the system to study thin-film magnetism with magnetic measurements utilizing optical techniques that require stable sample support.

This note describes a simple and inexpensive ultrahigh vacuum manipulator and translation/rotation stage. Our design criteria included sample translation over comparati- vely long distances (36 in.), full rotation capability, and sample heating to 1500 K and ceooling to 100 K.

Figure 1 illustrates the assembled manipulator. Pre- viously, investigators ‘-lo have reported manipulators with some but not all of these features. All parts of the manipula- tor mount to a common base [Pig. 1 (a) 1. The base, made of angle aluminum, need not be flat. We used kinematic mounts (not shown in Fig. 1 ), secured to the sides, for pre- cise angular alignment of the manipulator with respect to the vacuum chamber(s) .The key design feature of the manipu- lator is the linear rail [Fig. 1 (b) ] used for translation.” The use of a linear rail possesses several advantages. The small vertical height and horizontal width leads to a compact de- sign that can tit into restricted space constraints. The rail possesses a torque rating of 146 ft lb. (larger are available), high enough to preclude the problem of binding so common in such linear manipulators. Indeed, one significant feature of our design is that there is no sliding contact in the transla- tion device at all; all contacts involve rolling as opposed to sliding coefficients of friction. The linear rail also possesses an acentric pin (not shown in Fig. 1) adjustment for control of the uncertainty in horizontal motion. The manipulator design also insures that the linear motion stage is physically well-separated from the vacuum components that must be baked to reach ultrahigh vacuum. The ball thread is coupled to a synchronous motor [Fig. I (d) ] that can be easily en- gaged or decoupled. By shimming the motor and including a flexible coupling between motor and ball thread, we retained both the mechanical speed of using a motor and the accuracy (0.02” uncertainty) of manual adjustment.

The actual vacuum components are clamped to the base and linear rail by aluminum clamps. An additional advan- tage of this design is that, by inserting a gate valve between manipulator and chamber, the manipulator can be used as a load lock chamber.

The assembly of the manipulator is particularly simple. We were able to routinely align the threaded ball rod holders at each end of the manipulator to an accuracy of 0.006 in. over a distance in excess of 36 in. due to the accuracy of the linear track. Figure 2 illustrates view A-A in Fig. 1. The recirculating ball bearing design of the linear rail, illustrated in Fig. 2, is an important reason why our design does not

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have any binding problem. Our design provides for precise adjustment of the base-to-sample holder (H in Fig. 2) by shimming at the location emphasized by an arrow.

Figure 3 illustrates view B-B of Fig. 1. Note that part of Fig. 3 illustrates components that are in air and others that are in ultrahigh vacuum; the air-vacuum break denotes which are inside the tube (in vacuum). There are several noteworthy points about this aspect of our design. The base- to-sample holder height can be adjusted by shimming (ar- row) as with the section of Fig. 2. These two views, A-A and B-B, constitute the only places where vertical alignment is necessary, simplifying aligning along the vertical axis. The hole (labeled D in Fig. 3) provides access for the bypass screw [Fig. 1 (e) ] and thus for precise linear translation alignment. The three bearings [Fig. 3 (a) ] and associated bearing mounts [Fig. 3 (b) ] serve two purposes. In addition to providing a precise alignment and support for the sample holder [ Fig. 3 (c) 1, the bearings/mounts provide maximum pumping speed from the manipulator to the main vacuum vessel, thus preventing a virtual leak from developing. Note that the bearings (Part A) serve mainly as guides and are deliberately underloaded to prevent binding in vacuum. As designed, the bearings can be changed to accommodate tube outside diameters between 0.25 in. and 1.0 in., simply by changing one dimension of the bearing mount.

Figure 4 illustrates the actual sample holder. The hol- low center [Fig. 4(a) ] can be filled with liquid nitrogen. This lowers the sample temperature to 100-l 10 K. The sam- ple can be heated while using liquid nitrogen, so the tempera- ture can be stabilized to within 5 K at 100 K or higher. The sample can be heated resistively, with a current capability of 30 amps, sufficient to reach a sample temperature of 900- 1000 “C. To reach higher temperatures, a three-conductor sample holder was designed. This provided for a filament to utilize electron beam heating and a rod to support and elec- trically isolate the sample. In such a configuration, the fila- ment was typically near ground potential and the sample at

cl/ 0-J FIG. 1. Assembly drawing. Parts include (a) the base, (b) linear rail, tcf ball thread and ball screw, (d) synchronous motor, and (e) bypass screw. Views A-A and B-B are discussed in subsequent figures.

244 Rev. Sci. Instrum. 62 (l), January 1991 QQ34-6748/91 /QlQ244-Q2$Q2.QQ @ 1990 American institute of Physics 244 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP:

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FACE VIEW

i 0

/AIR-VACUUM BREAK

FIG. 2. Cross-section A-A of manipulator. The angle aluminum base sup- ports the rail and manipulator. The manipulator clamp is inexpensive and easily adapted for different sizes of manipulators. Vertical alignment can be made by shimming (arrow) the height H.

1ooO-2ooO V positive with respect to the filament. The fila- ment-to-sample distance was approximately 1.0 cm. The electron beam heater arrangement provides the capability to heat the sample to above 1500 “C. Since all components of the holder mount on the same flange and are rigidly affixed, the sample was easily rotated using a differentially pumped rotary motion feedthrough.

In summary, the present sample translation and manip- ulator provides for sample translation of 36 in. with an accu- racy of better than 0.02 in. The sample can be rotated fully 360”. The sample can be heated up to 900-1000 “C with resis- tive heating and to above 1500 “C with electron beam heat- ing. The sample can be cooled to 100-110 K using liquid nitrogen.

FIG. 3. Cross-section B-B’of manipulator. The three ball- bearing supports provide rolling contacts for low fric- tion motion. The precise sample holder alignment can becontrolled by adjusting the relative location of the bear- ing supports (arrows), since parts (a) and (b) are sepa- rate and screwed together. Part (c) is the sample holder. Part (d) is the hole for the bypass screw. The relative height of the parts at the two ends of the manipulator can be adjusted by shimming the overall part at the base (hori- zontal arrow). The air-vacu- um break denotes the wall of the vacuum vessel.

SIDE, TOP VIEWS

FIG. 4. Sample holder. The face view includes (a) the cold stage and hold- er, (b) the outer cylinder, which provides protection for the wires to the sample and prevents fouling of the wires on the support parts, and (c) the wires that are used to heat the sample and (thermocouple wires) measure the sample temperature. The side view illustrates (a) the sample, (b) the wires to the sample, (c) the outer cylinder, (d) the overall flange on which everything mounts, allowing for full 360” rotation, and (e) the tube for liq- uid nitrogen.

We benefitted from conversations with Art Fritzsche, William Cotter, Matthew Thompson, and James Erskine. Keith Perkins assisted us with machining some of the sup- port components. Financial support was provided by the Department of Energy and the Wisconsin Alumni Research Fund. One of us (P.C.) benefitted from University of Wis- consin college work study and senior thesis program support during this work.

’ K. D. Jamison and F. B. Dunning, Rev. Sci. Instrum. 55, 1509 ( 1984). ‘J. A. Stroscio and W. Ho, Rev. Sci. Instrum. 55, 1672 (1984). ‘J. Beauvillain, A. Claverie, and B. Jouffrey, Rev. Sci. Instrum. 56, 418

(1985). ‘N. J. Wu and A. Ignatiev, Rev. Sci. Instrum. 56,725 (1985). ‘5. J. Zinck and W. H. Weinberg, Rev. Sci. Instrum. 56, 1285 (1985). ‘T. Engel, D. Braid, and E. H. Conrad, Rev. Sci. Instrum. 57,487 ( 1986). ‘T. Castro and R. Reifenberger, Rev. Sci. Instrum. 58,289 ( 1987). ‘E. C. Teague, R. D. Young, F. Scire, and D. Gilsinn, Rev. Sci. Instrum.

59,67(1988). ‘A. Z. Moshfegh and A. Ignatiev, Rev. Sci. Instrum. 59,2202 ( 1988). ‘(ID. 3. Peters and B. L. Blackford, Rev. Sci. Instrum. 60, 138 (1989). ” Such linear rails, ball thread and ball screw parts are available from sever-

al companies. We have used components from THK America, Inc., 1300 Landmeier Rd., Elk Grove Village, IL 6OtXJ7.

245 Rev. Sci. Instrum., Vol. 62, No. 1, January 1991 Notes 245 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP:

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