US 3466079 A
Description (OCR text may contain errors)
Sept. 9, 1969 w. K. MAMMEL PRESSURIZED FLUID PICKUP DEVICE 2 Sheets-Sheet 1 Filed Sept. 8, 1965 A 7' TORNE Y INVE/VT'OR W. K. MAM/WEI. BY 1?.
p 1969 w. K. MAMMEL 3,466,079
PRESSURIZED FLUID PICKUP DEVICE Filed Sept. 8, 1965 2 Sheets-8119a; 2
I I! 1] ll vHI ||l II w ll ha! 1 H I' l I 47 l United States Patent 3,466,079 PRESSURIZED FLUID PICKUP DEVICE Walter K. Mammal, Yardley, Pa., assignor to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Sept. 8, 1965, Ser. No. 485,751 Int. Cl. B66c 1/02 US. Cl. 294--64 2 Claims ABSTRACT OF THE DISCLOSURE A pressurized fluid pickup device which consists of a head with a central orifice through which fluid under pressure is applied to a workpiece. Means are provided at the periphery of the head to direct fluid away from the work piece. The workpiece is maintained in a suspended condition spaced from the head as a result of the balance maintained between the weight of the workpiece, the atmospheric pressure and the sub-atmospheric pressure-produces by fluid passing across the face of the workpiece which is adjacent the head.
This invention relates to a pressurized fluid pickup device and more particularly to a readily manipulatable gun having facilities for picking up a thin slice of semiconductor or other material without physical contact and holding the slice in a spaced position.
In the fabrication of semiconductor devices such as transistors, thin circular slices of doped silicon or other materials are used to impart the semiconductor characteristics. The fabrication requires multi-processing and handling steps that must be performed with a minimum degree of contamination of the slices. At the same time, extreme care must be exercised to avoid scratching, fracturin'g, or chipping of the slice which is extremely brittle.
At present, various tweezers, vacuum pickup devices, and other clamping or gripping devices are being used. All of these devices result in physically gripping the slice, resulting in both a considerable amount of contamination and physical damage.
Further, in the processing of the slices, at least one surface must be treated, cleaned or etched to have a surface on which the semiconductor may be constructed. Various facilities are being used to swirl or orbit the slices in .a cleaning solution to obtain maximum flow of solution across the surface to insure a resultant surface that is clean and free of ridges and/or grooves. Again, these facilities are subject to problems of physically gripping or holding the slices, thus subjecting them to damage and contamination. i
An object of this invention resides in a new and improved pressurized fluid pickup device.
A further object of the invention is the provision of a portable pickup device utilizing either gaseous or liquid fluid for retaining a slice in spaced relation with the device during transport or processing of the slice.
An additional object of the invention is the provision of a pressure pickup device wherein fluid is passed across a surface of a semiconductor slice with suflicient velocity to hold the slice spaced from the device while the fluid also acts to clean, heat, dry,'etch, and/or remove foreign particles or otherwise treat the surface of the slice.
Another object of the invention resides in applying pressurized fluid through and then laterally along a flat surface with sufficient velocity to hold an article spaced from the surface whereafter the laterally moving fluid is exited through an array of passageways spaced about the periphery of the surface.
3,466,079 Patented Sept. 9, 1969 A still further object of the devices is the provision of a pressure pickup devise with facilities for precluding or limiting lateral shifting of an article held by the device.
With these and other objects in view, the present invention contemplates a fluid pressure pickup and transport device wherein pressurized fluid is passed over an article to lift and hold the article suspended in spaced relationship to a reference surface on the device, and there are facilities on the surface for precluding or limiting lateral shifting of the article relative to the surface.
. More particularly, the device is in the form of a triggerin the velocity head of the escaping pressurized fluid.
The article will move toward the reference surface until there is a balancing of the total forces acting on both the top and bottom surfaces of the article.
Other objects and advantages of the present invention will be apparent from the following detailed description when considered with the accompanying drawings, wherein:
FIG. 1 is a side elevational View of a pressurized fluid pickup gun embodying the principles of the present invention;
FIG. 2 is a plan view of a pickup head of the gun shown in FIG. 1 in which there is illustrated stops for limiting lateral shifting of an article relative to the pickup head;
FIG. 3 is a cross-sectional view of an alternativeembodiment of a pickup head having passageways to preclude the lateral escape of pressurized fluid;
FIG. 4 is a plan view of the face of the head shown in FIG. 3 particularly illustrating an array of passageways for receiving the escaping fluid;
FIG. 5 is a side elevational view of an additional embodiment of the invention showing vacuum means for collecting the escaping pressurized fluid;
FIG. 6 is a cross-sectional view of a further embodiment of the invention wherein the pickup head is provided with a fluid exit skirt; and
- FIG. 7 is a plan view of the face of the head show in FIG. 6 particularly illustrating the construction and muonting of the skirt.
Referring to FIGS. land 2, there is shown an embodiment of the invention comprising a gun-like'device for picking up a thin slice 10 of material, such as silicon. The silicon slice 10 has a surface which may be polished or etched or the surface may be coated with a photoresist. In the illustrated embodiments of the invention, the slice is shown as being in the shape of a disc, but it is contemplated that other shaped slices or articles may be picked up and transported. In handling these silicon slices, it is important that the surface be maintained free of scratches and contaminants, such as grease, dirt, or materials that might diffuse into the slice. The gunlike device is designed to pick up and hold the slice with out actually making physical contact with either face.
passageway 16 terminates in a coupling 17 connected to a line or conduit 18 running through a conventional slide valve 19 to a further air line or conduit 21 terminating in a bushing 22. This bushing 22 enables ,a connection.
to be established between the air line 21 and an air hose or conduit 23 running to a source 24 of compressed air or other pressurized fluid.
The head 12 is provided with a circumferential array of projecting lugs 25 which are tapered to a point 26 or to a rounded end 26 to prevent or limit shifting of the slice relative to the surface 13. The circumferential spacing of lugs 25 is less than the diameter or smallest diagonal dimension of the slice 10.
The head 12 may be constructed of quartz or other material that will not mar, contaminate, or tend to scratch the surface of the slice or otherwise degrade the slice, if contact with the slice should be made during pickup, handling, or treatment of the slice. Further, the head may be constructed of transparent material which will permit the viewing of the top surface of the slice 10 during pickup and transport.
Air or other fluid is selectively applied to the exit orifice 14 by operation of a trigger 27 pivotally mounted on the handle 11. The trigger 27 engages a spring-urged actuator rod 28 to open and close the valve 19. A knurled thumb nut 29 is mounted on a threaded portion of the rod 28 to vary the spring pressure on the trigger.
In use of the gun, the surface 13 of the head 12 is moved over a slice 10. The trigger 27 is depressed to apply pressurized fluid through the line 18, the coupling 17, the passageway 16, and then through the exit orifice 14, whereupon the air is laterally deflected and the slice is picked .up. The pickup action results because the total pressure head on the top of the slice must be maintained constant in accordance with Bernoullis theorem. More particularly, during pickup, the total pressure head on one planar surface of the slice facing the surface 13 comprises a velocity head plus a static head which is less than atmospheric pressure. On the other side of the slice there is a static head which is at atmospheric pressure, thus there is static pressure differential which is sufficient to act against and move the slice toward the surface 13. As the slice moves closer to the surface 13, the space or gap for the air escape decreases resulting in greater opposition to air flow. The opposition to air flow is accompanied by a decrease in the velocity head so that the slice moves toward the surface 13 until there is a balance between the total pressure heads acting on both surfaces of the slice. If the air pressure increases, there is a corresponding increase in the velocity head and as a consequence, reduction in the static head resulting in the atmospheric static head forcing the slice to move closer to the surface 13.
In the use of the gun, it is near impossible to center the exit orifice over the slice 10; thus, there will be more fluid passing over one section of the slice than over a diametrically opposed section. As a result, there is a force component tending to laterally shift the slice relative to the reference surface 13. Shifting of the slice 10 is limited by the lugs 25 with either the points 26 or the rounded ends 26'.
It may be appreciated that the surface of the slice 10 facing the reference surface 13 is not engaged during the holding of the slice in the suspended position. The slice 10 is supported at a distance from the reference surface 13 on a layer of flowing fluid so long as the pressurized fluid is applied to the passageway 16. The fluid impressed from source 24 may be ordinary air or it may be a special atmosphere which is utilized to treat the surface of the slice 10 exposed to the fluid. It is to be further understood that the fluid may be in the form of a liquid and the slice will be again held in the suspended position. In this instance, the fluid may have a detergent for cleaning the surface of the slice. Further, the liquid may be an etchant solution in which case the head 12 may be immersed in a tank of etching solution so that the top surface of the slice is rapidly etched and cleaned by the etchant flowing out of exit port 14. After the slice is treated with a liquid, it may be rapidly dried by applying heated air or other gaseous atmosphere through the gun.
Referring now to FIGS. 3 and 4, there is shown an alternative embodiment comprising a head 32 having a passageway 36 for receiving fluid passed through a coupling 37 connected to the gun shown in FIG. 1. In this instance, a circumferential array of passageways 38 are equally spaced about an exit orifice 34. A projecting rim 39 is formed about the entire periphery of the head 32 to prevent lateral shifting of a held slice 10.
In use of this embodiment, the fluid emanating from the exit orifice 34 laterally passes between the bottom surface of the head 32 and the top surface of the slice 10 and then passes through passageways 38. There is no lateral emission of fluid from the outer periphery of the head 32 thereby precluding the disturbance of other slices 10 that may be in the vicinity of the picked up slice.
Referring now to FIG. 5, an additional embodiment of the invention is disclosed comprising a gun 41 connected to a head 42 having a flat surface 43 in which there is formed an exit orifice 44 of an air pasageway 46. Passageway 46 terminates in a coupling 47 connected to a fluid line 48 running through a conventional valve 49 to a further air line 50 terminating in a bushing 51. The bushing 51 is connected to a conduit running to a source of pressurized fluid 52.
The head 42 is provided with a circumferential array of passageways 53 terminating at one end in the surface 43 and in the other end in a manifold 54. The manifold 54 communicates with a coupling 56 that is connected to a line 57 running to a valve 58 which is operated by the same trigger mechanism used to operate the valve 49. This trigger mechanism 59 is substantially the same as that shown in FIG. 1. The valve 58 is connected through a line 60 to a coupling 61 attached to a line 62 terminating in a vacuum pump 63.
The surface 43 is surrounded by a continuous projecting rim 64 similar to rim 39 (FIG. 4) which again limits lateral shifting of a slice 10 relative to the surface 43.
In operation of this embodiment, the trigger mechanism 59 is operated to open valves 49 and 58 whereupon pressurized fluid emanates from the exit port 44 to act on and hold a slice 10 suspended from the surface 43. The laterally moving fluid readily passes into the vacuum lines 53 and through the manifold 54 and thence through the line 57, the valve 58, and the line 59 to vacuum pump 63.
Referring to FIGS. 6 and 7, there is shown a further embodiment of the invention having facilities for limiting the lateral shifting of a held slice and for receiving and deflecting the laterally moving lifting fluid. In this embodiment, head 71 is again provided with an axial passageway 72. The head 71 is circular in shape and is provided with a plurality of radial fins 73 secured to the circumference of the head 71. Mounted on the ends of the fins 73 is a skirt or sheet-like ring 74. The lower portion 75 of fins 73 are wedge-shaped, similar to the lugs 26 or 26' shown in FIGS. 1 and 2. The skirt depends a predetermined distance below a reference surface 76 formed by the face of the head 71. Attached to, or formed integral with the end of the skirt 74, is an inwardly extending flange or lip 77.
In use of this embodiment, air is impressed through the passageway 72 and laterally flows across surface 76 to provide a reduced static head which acts on a slice 10 to lift and hold the slice in suspension. The slice 10 is held at a distance which is less than the distance the flange 77 is spaced from the surface 76 so that the laterally moving air is directed past the flange 77 into the space between the circumference of the head 71 and the skirt 74. Lateral shifting of the slice 10 is limited by the depending portion of the skirt 74.
It is to be understood that the above-described arrangements of apparatus and construction of elemental parts are simply illustrative of applications of the principles of the invention and many other modifications may be made without departing from the invention.
What is claimed is: 1. A pressurized fluid pickup device for lifting an article having a planar surface comprising,
handle means having a pair of fluid conduits running therethrough,
a circular head having an axial passageway therethrough terminating in an exit orifice formed in a planar end surface of said head,
a plurality of support fins projecting from said circumference of said head,
a head attached to said handle having a flat surface, 5 a ring skirt mounted on said fins to project beyond said said head having a centrally disposed passageway in planar end surface,
communication with a first of said fluid conduits and said ring skirt having an inwardly projecting flange that terminating in said flat surface, is spaced a predetermined distance from said planar said head having a group of passageways radially dis- 10 surface, and
posed about said central passageway in communimeans for forcing air through said passageway against cation with a second of said fluid conduits and tera slice of material to laterally deflect the air with minating in a group of radially disposed orifices in sufficient velocity to lift and hold said slice at a dissaid flat surface, tance which is less than said predetermined distance means for applying pressurized fluid to said first fluid whereupon said laterally deflected air passes between conduit, said head and flange and then between said head and means for applying vacuum to said second fluid consaid ring skirt.
duit, and valve controlled means for selectively applying said References Cited pressurized fluid from said first conduit through said UNITED STATES PATENTS gg passage? to ig i flow aclioss 2 2 0 5 4 1942 in 294 64 p anar sur ace 0 sai article with sufliclent velocity to impress a lifting force on said article in 3223443 12/1965 Mlsson 294 65 accordance with Bernoullis theorem and for simul- FOREIGN PATENTS taneously applying vacuum to said radially disposed passageways through said second conduit to withdraw the fluid flowing across said flat surface.
944,175 12/1963 Great Britain.
GERALD M. FORLENZA, Primary Examiner 2. In a device for lifting and holding a thin slice of G. F. ABRAHAM, Assistant Examlner material in suspension,