US3703881A - Apparatus for ultra-high vacuum in situ thin film studies - Google Patents

Abstract

A thin film fabricating and test apparatus has a substrate holder cart positioned on a pair of tracks within a tubular vacuum system. Feed through drive units operate to move the cart to positions adjacent deposition units and test units within the vacuum system. A second drive unit positions the cart and moves masks and test contacts to a position adjacent substrate. A third drive unit positions deposition control shutters adjacent the substrate.

Description

[451 Nov. 28, 1972 United States Patent Rut et a].

[54] APPARATUS FOR ULTRAJ'IIGH 10/1964 Harshberger..........104/l 19 X VACUUM IN SITU THIN FILM STUDIES 9/1969 Bukkila et 18/49 X [72] Inventors: Franz X. Rut, Kettering; Wayne R.

3,152,559 3,469,560 3,473,510 lO/l969 Sheng et al. 1 18/495 Chase, Dayton; Raymond A. Preil, Fairbom, all of Ohio [73] Assignee: The United States of America as m m M u m m m m m wk mm mm 2 m z w 1 m 9 a mmm represented by the Secretary of the Air Force pparatus has a subolder cart positioned on a pair of tracks within a tubular vacuum system. Feed through drive units strate h [22] Filed: May 13, 1971 [21] App]. No.: 143,080

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4Ciains,l8DrawingFigures [56] References Cited ,536 Ma1oney....................104/119 APPARATUS FOR ULTRA-HIGH VACUUM IN SITU THIN FILM STUDIES BACKGROUND OF THE INVENTION When testing advanced electronic devices, it is difficult to obtain the basic device properties so as to gain a more quantitative understanding of the basic physical principles governing the device. This is due to the fact that it is impossible to separate the basic device properties from the effects due to contamination.

BRIEF SUMMARY OF THE INVENTION According to this invention, an apparatus is provided for fabricating test samples, for performing surface treatment and for measuring selected properties without removing the sample from the vacuum chamber. A stainless-steel tube has a transport system, supported therein on spaced supports, which is used to move a test sample from stage to stage. The operations performed at the various stages are determined by the particular test sample being constructed and tested. For example, operating stages could be provided for masking the substrate and depositing thin-films, for surface treating the device, and a stage where electrical contacts are made with the sample so that various tests can be made on the sample. The apparatus is made of materials such as stainless steel, titanium, tantalum and boron nitride so that the apparatus can be baked under vacuum conditions to 450 C. Also, the apparatus is constructed to permit vacuum conditions of the order of 10- Torr. The apparatus is made up of units which can be attached together in various combinations to perform different operations.

IN THE DRAWINGS FIG. 1 is a schematic diagram partially in block form of a fabrication and test apparatus according to the invention.

FIG. 2 is a top view of the drive section for the device of FIG. 1.

FIG. 3a is an isometric view of the transport assembly for the device of FIG. 1.

FIG. 3b is an enlarged isometric view of a portion of the device of FIG. 30.

FIG. 4 is an end view of the cart for the device of FIG. 3. g

FIG. 5 is a back view of the device of FIG. 4.

FIG. 6 is a top view of the device ofFIG. 4.

FIG. 7 is a schematic view of the cart device assembly for the device of FIG. 3.

FIG. 8 is an enlarged isometric view of the shaft couplers for the device of FIG. 3.

FIG. 9 is an enlarged view of the mask and indexing mechanism for the device of FIG. 3.

FIG. 10 is an enlarged top view of the shutter mechanism for the device of FIG. 3.

FIG. 11 is an enlarged partially cut away end view of the test read out station for the device of FIG. 3.

FIG. 12 is the bottom view of a substrate as placed in the cart for processing in the device of FIG. 1.

FIG. 13 is the top view of the mask used for deposition of silver on the substrate of FIG. 12.

FIG. 14 is the bottom view of the substrate of FIG. 12 with silver deposited thereon.

FIG. 15 is the top view of the mask used for deposition of cesium on the substrate of FIG. 14.

FIG. 16 is the bottom view of the substrate of FIG. with silver and cesium deposited thereon.

FIG. 17 is a schematic diagram of the test station for the device of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Reference is now made to FIG. 1 of the drawing wherein reference number 10 shows an electronic device fabricating and testing apparatus, made up of a plurality of individual tubular sections 12, 14 and 16. Although three sections are shown, more or fewer sections, or sections different from those shown can be used.

Section 12 has a cesium deposition unit shown schematically at 17 and a test section shown at 19. Units 22, 23, and 24 have transparent windows, not shown. The unit 21 and window 23 are unused in this system. Window 22 is used for viewing and window 24 is used to illuminate the test device to obtain test data.-

Section 14 has three drive units 27, 28 and 29 as shown in FIG. 2. The drive units 27, 28 and 29 may be conventional drive units, for example, magnetic drive units. Unit 31 is a silver deposition unit and unit 32 has a viewing window. In section 14 units 34, 35 and 36 are unused, however, one of these could be used for vacuum testing.

Section. 16 has a roughing vacuum pump 38 and an ion vacuum pump 40. Other vacuum pumps can be provided as needed.

When the apparatus shown in FIG. 1 is baked out, parts that will not withstand the baking temperature, such as drive units 27, 28 and 29, are removed.

FIGS. 3a and 3b show the test sample transport system 42 used in the device of FIG. 1. Portion 44 of the transport system is positioned within tubular section l2,and portion 46 is positioned within tubular section 14. All of the parts of the system are made of stainless steel unless otherwise specified.

The transport system 42 is supported within the tubular sections 12 and 14 by means of support plates 48. The plates are positioned by means of adjustable support legs 49 which are threaded into tantalum leg blocks 51.

A pair of tracks 52 and 53 extend the length of units 12 and 14 with the ends of one section abutting the ends of the other section. Tracks 52 and 53 are placed on one side of the system so as to leave the other side free for use of the equipment used in fabricating and testing the test device.

A cart 55, shown in greater detail in FIGS. 4-6, rides along the tracks in cantilever fashion and is held on the tracks by its weight. A pair of pulley- like wheels 57 and 58 are secured to cart side plate 64 and ride on circular track 52 and serve to guide the cart. A flat wheel 59 is also secured to side plate 64 and rides on the under side of track 53. The cart and wheels are made of titanium to reduce weight.

The cart is moved along the tracks by means of a The cable 60 passes around cable drive wheel 73, which is driven by drive unit 28, and around idler pulleys 75 and 76. Pulley 75 is spring loaded, as shown in FIG. 7, to allow for changes in cable length during bake out.

Three shafts 78, 79, and 80 extend the length of the two sections and act to operate the processing equipment at the various stations. The shafts from portion 44 are coupled to the shafts from portion 46 by slip apart couplings 81, as shown in FIG. 8. Shafts 78 and 79 are operated by motion rod 82 which is driven by drive unit 29 to move mask holders 84 and indexing rods 89 and contact bar 87 into position adjacent the test sample and index bar 65. Shaft 79 is moved by cam 90 and in turn moves shaft 78 through shaft coupler 92. Shaft coupler 92 was replaced by sector gears in a later model.

The shutter shaft 80 is gear driven from shaft 94 which is driven. by drive unit 27. I

The shutter mechanism is shown in greater detail in FIG. 10. The shutter 94 is held .closed by a spring 95 secured to support plate 48. A monitor shutter 97 is secured to shaft 80 at 96 and is opened by the initial movement of shaft 80 to permit control of the evaporation rate by a conventional evaporation monitor sensor, not shown. Continued rotation of shaft 80 causes arm 99, which is secured to shaft 80, to engage a pin 101 secured to one of the shutter supports 103 to which shutter support arms 104 are also attached. Movement of pin 101 acts to open the substrate shutter 94. The shutter supports 103 are supported on shaft 80 by means of rotatable boron nitride bushings 105.

Electrical contact is made with the test sample by means of gold fuzz buttons 107 on a boron nitride block 108. Leads connected to the fuzz buttons 107 pass out through unit 19 in FIG. 1.

g In the operation of the apparatus, a substrate such as shown in FIG. 12, is secured by the tantalum clips 71 in the substrate holder 67 of the substrate cart 55. The substrate shown in FIG. 12 has an aluminum strip 111, aluminum oxide insulators 113 and gold contacts 115 thereon. The substrate shown in FIG. 12 can be produced external to the system and then placed on the substrate can 55 for additional processing, or it could be produced within the apparatus by providing additional operating stations. After the substrate, as shown in FIG. 12, is secured to the cart 55, the system is sealed and evacuated and baked to outgas all of the parts. Drive unit 28 is then operated to position the cart adjacent the unit 31. Drive unit 29 is then operated to engage the indexing rod 86 into engagement with the center notch 66 in indexing bar 65 and to move the mask holder 84 with a mask such as shown in FIG. 13 adjacent the substrate.

Drive unit 27 is then operated to permit monitor shutter 97 and substrate shutter 94 to move into position over the mask holder. The silver deposition unit is then energized and the monitor shutter 97 is opened to set the deposition rate in the conventional manner. When the proper deposition rate is established, the substrate shutter 94 is opened to deposition of silver strips 117 onto the substrate to the desired thickness in a pattern as shown in FIG. 14. The shutters are then returned to their position over the mask holder and the silver deposition unit is de-energized. When silver Cart drive unit 28 is then operated to move the cart adjacent the cesium deposition unit 17, where cesium is deposited with a conventional cesium gun in a like operation except that cesium is deposited through one aperture at a time in the mask of FIG. 15. The cart is positioned for separate deposition of cesium layers 1 19 by having the index rod'86 engage the separate'slots 66 in the index bar 65. When cesium deposition is completed, the cart 55 is moved adjacent the test unit 19. Operation of drive 29 moves index rod 86 into engagement with the center slot 66 of index bar 65and moves the fuzz button contacts 107 into engagement with substrate contacts 115, shown in 17. The unit is then illuminated through window 24, as shown schematically in FIG. 17 and the desired tests may be made on the test device.

There is thus provided a device for fabricating a test sample and for measuring selected properties without removing the test sample from the vacuum chamber.

While only one system for fabrication and test has been described, more and differentfabricating and test units could be used for making and testing different test devices than that described. Also, other materials than those described could be usedin the apparatus. Any high vacuum compatible materials which meet the mechanical requirements may be used, for example, oxygen free hard copper could be used for many of the parts.

We claim:

1. The combination, comprising: a tubular vacuum system including deposition and testing chambers; a plurality of spaced supports disposed within said tubular system; a first bar member, having a rectangular cross section, secured to said space supports and forming a first cart track; a second bar member, having a circular cross section, secured to said spaced supports and forming a second cart track; said bar members being vertically and horizontally spaced from one another; a cart adapted to run on said first and said second cart tracks; said cart including a test specimen support and means for supporting said' cart and test specimen support in cantilever relation on said first and said second cart track; and means for moving the cart along said tracks and through said chambers.

2. In the combination recited in claim 1, wherein means for supporting the cart and test specimen in cantilever relation on said first and said second cart track includes a cart side member with a first and a second pulley type wheel engaging the bar member with a circular cross section and a third wheel engaging, the under side of the bar member with the rectangular cross section.

3. In the combination as recited in claim 1 wherein are provided mask and shutter mechanisms and feed through drive means for positioning said masks and shutter mechanisms adjacent the test specimen to control the deposition of active material to the test specimen.

4. In the combination as recited in claim 3 wherein the active material is photoelectric material-and the means for testing the specimen includes means for making predetermined electrical Contact with the test specimen and means for illuminating the test specimen.

Claims (4)

1. The combination, comprising: a tubular vacuum system including deposition and testing chambers; a plurality of spaced supports disposed within said tubular system; a first bar member, having a rectangular cross section, secured to said space supports and forming a first cart track; a second bar member, having a circular cross section, secured to said spaced supports and forming a second cart track; said bar members being vertically and horizontally spaced from one another; a cart adapted to run on said first and said second cart tracks; said cart including a test specimen support and means for supporting said cart and test specimen support in cantilever relation on said first and said second cart track; and means for moving the cart along said tracks and through said chambers.

2. In the combination recited in claim 1, wherein means for supporting the cart and test specimen in cantilever relation on said first and said second cart track includes a cart side member with a first and a second pulley type wheel engaging the bar member with a circular cross section and a third wheel engaging the under side of the bar member with the rectangular cross section.

3. In the combination as recited in claim 1 wherein are provided mask and shutter mechanisms and feed through drive means for positioning said masks and shutter mechanisms adjacent the test specimen to control the deposition of active material to the test specimen.

4. In the combination as recited in claim 3 wherein the active material is photoelectric material and the means for testing the specimen includes means for making predetermined electrical contact with the test specimen and means for illuminating the test specimen.

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