|Publication number||US20080054885 A1|
|Application number||US 11/977,130|
|Publication date||Mar 6, 2008|
|Filing date||Oct 23, 2007|
|Priority date||Sep 5, 2000|
|Also published as||DE10143175A1, DE20114545U1, US6965226, US7352168, US7423419, US7501810, US7514915, US7518358, US7969173, US20020027433, US20060028200, US20080042374, US20080042642, US20080042674, US20080048647, US20080048648, US20080054883, US20080054884, US20100109695|
|Publication number||11977130, 977130, US 2008/0054885 A1, US 2008/054885 A1, US 20080054885 A1, US 20080054885A1, US 2008054885 A1, US 2008054885A1, US-A1-20080054885, US-A1-2008054885, US2008/0054885A1, US2008/054885A1, US20080054885 A1, US20080054885A1, US2008054885 A1, US2008054885A1|
|Original Assignee||Cascade Microtech, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (4), Classifications (18), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a division of U.S. patent application Ser. No. 11/204,910, filed Aug. 15, 2005, which is a continuation of U.S. patent application Ser. No. 09/877,823, filed Jun. 7, 2001, now U.S. Pat. No. 6,965,226, which claims the benefit of U.S. Provisional App. No. 60/230,212, filed Sep. 5, 2000.
The present application relates to an improved chuck.
With reference to
Mounted atop the platen 12 are multiple individual probe positioners such as 24 (only one of which is shown), each having an extending member 26 to which is mounted a probe holder 28 which in turn supports a respective probe 30 for contacting wafers and other test devices mounted atop the chuck assembly 20. The probe positioner 24 has micrometer adjustments 34, 36 and 38 for adjusting the position of the probe holder 28, and thus the probe 30, along the X, Y and Z axes, respectively, relative to the chuck assembly 20. The Z axis is exemplary of what is referred to herein loosely as the “axis of approach” between the probe holder 28 and the chuck assembly 20, although directions of approach which are neither vertical nor linear, along which the probe tip and wafer or other test device are brought into contact with each other, are also intended to be included within the meaning of the term “axis of approach.” A further micrometer adjustment 40 adjustably tilts the probe holder 28 to adjust planarity of the probe with respect to the wafer or other test device supported by the chuck assembly 20. As many as twelve individual probe positioners 24, each supporting a respective probe, may be arranged on the platen 12 around the chuck assembly 20 so as to converge radially toward the chuck assembly similarly to the spokes of a wheel. With such an arrangement, each individual positioner 24 can independently adjust its respective probe in the X, Y and Z directions, while the jacks 14 can be actuated to raise or lower the platen 12 and thus all of the positioners 24 and their respective probes in unison.
An environment control enclosure is composed of an upper box portion 42 rigidly attached to the platen 12, and a lower box portion 44 rigidly attached to the base 10. Both portions are made of steel or other suitable electrically conductive material to provide EMI shielding. To accommodate the small vertical movement between the two box portions 42 and 44 when the jacks 14 are actuated to raise or lower the platen 12, an electrically conductive resilient foam gasket 46, preferably composed of silver or carbon-impregnated silicone, is interposed peripherally at their mating juncture at the front of the enclosure and between the lower portion 44 and the platen 12 so that an EMI, substantially hermetic, and light seal are all maintained despite relative vertical movement between the two box portions 42 and 44. Even though the upper box portion 42 is rigidly attached to the platen 12, a similar gasket 47 is preferably interposed between the portion 42 and the top of the platen to maximize sealing.
With reference to
Atop the octagonal box 48, a circular viewing aperture 58 is provided, having a recessed circular transparent sealing window 60 therein. A bracket 62 holds an apertured sliding shutter 64 to selectively permit or prevent the passage of light through the window. A stereoscope (not shown) connected to a CRT monitor can be placed above the window to provide a magnified display of the wafer or other test device and the probe tip for proper probe placement during set-up or operation. Alternatively, the window 60 can be removed and a microscope lens (not shown) surrounded by a foam gasket can be inserted through the viewing aperture 58 with the foam providing EMI, hermetic and light sealing. The upper box portion 42 of the environment control enclosure also includes a hinged steel door 68 which pivots outwardly about the pivot axis of a hinge 70 as shown in
With reference to
With particular reference to
In addition to the circular elements 80 and 81, auxiliary chucks such as 92 and 94 are detachably mounted on the corners of the element 83 by screws (not shown) independently of the elements 80 and 81 for the purpose of supporting contact substrates and calibration substrates while a wafer or other test device is simultaneously supported by the element 80. Each auxiliary chuck 92, 94 has its own separate upwardly-facing planar surface 100, 102 respectively, in parallel relationship to the surface 82 of the element 80. Vacuum apertures 104 protrude through the surfaces 100 and 102 from communication with respective chambers within the body of each auxiliary chuck. Each of these chambers in turn communicates through a separate vacuum line and a separate independently-actuated vacuum valve (not shown) with a source of vacuum, each such valve selectively connecting or isolating the respective sets of apertures 104 with respect to the source of vacuum independently of the operation of the apertures 84 of the element 80, so as to selectively hold or release a contact substrate or calibration substrate located on the respective surfaces 100 and 102 independently of the wafer or other test device. An optional metal shield 106 may protrude upwardly from the edges of the element 83 to surround the other elements 80, 81 and the auxiliary chucks 92, 94.
All of the chuck assembly elements 80, 81 and 83, as well as the additional chuck assembly element 79, are electrically insulated from one another even though they are constructed of electrically conductive metal and interconnected detachably by metallic screws such as 96. With reference to
With reference to
Either coaxial or, as shown, triaxial cables 118 and 120 form portions of the respective detachable electrical connector assemblies 108 and 110, as do their respective triaxial detachable connectors 122 and 124 which penetrate a wall of the lower portion 44 of the environment control enclosure so that the outer shields of the triaxial connectors 122, 124 are electrically connected to the enclosure. Further triaxial cables 122 a, 124 a are detachably connectable to the connectors 122 and 124 from suitable test equipment such as a Hewlett-Packard 4142B modular DC source/monitor or a Hewlett-Packard 4284A precision LCR meter, depending upon the test application. If the cables 118 and 120 are merely coaxial cables or other types of cables having only two conductors, one conductor interconnects the inner (signal) connector element of a respective connector 122 or 124 with a respective connector element 108 a or 110 a, while the other conductor connects the intermediate (guard) connector element of a respective connector 122 or 124 with a respective connector element 108 b, 110 b. U.S. Pat. No. 5,532,609 discloses a probe station and chuck and is hereby incorporated by reference.
The chuck assembly 20 with corresponding vertical apertures 84 and respective chambers separated by O-rings 88 permits selectively creating a vacuum within three different zones. Including the three O-rings 88 and the dielectric spacers 85 surrounding the metallic screws 96 permits securing adjacent first, second and third chuck assembly elements 80, 81 and 83 together. The concentric O-rings 88 are squeezed by the first and second chuck assembly elements and assist in distributing the force across the upper surface of the chuck assembly 20 to maintain a flat surface. However, the O-rings and dielectric spacers 85 have a greater dielectric constant than the surrounding air resulting in leakage currents. Also, the additional material between adjoining chuck assembly elements 80, 81, and 83 decreases the capacitance between the adjoining chuck assembly elements. Moreover, the dielectric material of the O-rings and dielectric spacers 85 builds up a charge therein during testing which increases the dielectric absorption. The O-rings and dielectric spacers 85 provides mechanical stability against warping the chuck when a wafer thereon is probed so that thinner chuck assembly elements 80, 81, and 83 may be used. The height of the different O-rings and dielectric spacers 85 tend to be slightly different which introduces non-planarity in the upper surface when the first, second, and third chuck assembly elements 80, 81, and 83 are secured together.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.
Traditionally chuck designers use thin chuck assembly elements and many radially arranged screws in order to permit the screws to be tightened tightly without significantly warping any of the chuck assembly elements, and in particular the upper chuck assembly element. Maintaining a flat planar upper chuck assembly element is important to permit accurate probing of the wafer and avoid breaking, or otherwise damaging, the wafer while probing. In a multi-layered chuck, the lower chuck assembly element is secured to the middle chuck assembly element, the middle chuck assembly element in turn is secured to the upper chuck assembly element, which results in any non-uniformities of slightly different thicknesses of the chuck assembly elements and interposed dielectric elements creating a cumulative non-planarity. For example, non-uniformity in the planarity of the lower chuck assembly element and differences in the thickness of the dielectric spacers may result in the middle chuck assembly element being slightly warped when secured thereto. Non-uniformity in the planarity of the middle chuck assembly element, the slight warping of the middle chuck assembly element, and the differences in the thickness of the dielectric spacers and O-rings, may result significant warping of the upper chuck assembly element when secured to the middle chuck assembly element. Accordingly, the thicknesses and planarity of (1) each chuck assembly element, (2) dielectric spacers, and (3) O-rings, needs to be accurately controlled in order to achieve a planar upper surface of the upper chuck assembly element.
After consideration of the thin chuck assembly elements and the desire to minimize warping of the upper chuck assembly element, the present inventor came to the realization that a three point securement system, including for example three pins, permits defining the orientation of the upper chuck assembly element without inducing stress into the upper chuck assembly element 180, as illustrated in
Minimization of the spacers, such as O-rings, between the upper and middle chuck assembly elements reduces the capacitive coupling between the upper and middle chuck assembly elements to less than it would have been with additional dielectric layer material there between. The elimination of additional spacers likewise increases the resistance between adjacent chuck assembly elements.
Connecting each vacuum line(s) directly to the center of the upper chuck assembly element 180 normally requires at least one corresponding hole drilled radially into the upper chuck assembly element from which vertically extending vacuum chambers provide a vacuum to the upper surface 198 of the upper chuck assembly element. Machining the combination of radial and vertical holes requires highly accurate machining which is difficult, time consuming, and expensive. Machining such holes becomes increasingly more difficult as the size of the chucks increases.
After consideration of the difficulty of machining accurate holes into the side of the upper chuck assembly element 180, the present inventor determined that machining a set of airways 210 a-210 e in the lower surface 208 of the upper chuck assembly element is easier and tends to be more accurate, as shown in
The elimination of the O-rings between the adjacent upper and middle chuck assembly elements creates a dilemma as to of how to provide a vacuum to the top surface of the upper chuck assembly element, if desired. The present inventor determined that it is normally undesirable to attach a vacuum tube directly to the upper chuck assembly element because the exterior conductive surface of the vacuum tube is normally connected to shield potential. The shield potential of the exterior of the vacuum tube directly adjoining the upper chuck assembly element would result in an unguarded eakage current between the upper chuck assembly and the vacuum tube.
To provide a vacuum path between the middle chuck assembly element and the upper chuck assembly element a vacuum pin 206 interconnects respective vacuum lines and particular vacuum holes (e.g., “zones”) on the upper surface of the upper chuck assembly element, as illustrated in
The pin securing the middle chuck assembly element 182 to the upper chuck assembly element 180 includes a portion thereunder that is open to the lower chuck assembly element, normally connected to shield. More specifically, the pin 204 electrically connected to the upper chuck assembly element 180 provides an unguarded leakage path through the middle chuck assembly element 182 to the lower chuck assembly element 184. In existing designs, a small plate is secured over the opening to provide guarding. A more convenient guarding structure is a lower cover plate 230 over the pin openings, preferably covering a major portion of the middle chuck assembly element 182. The lower cover plate 230 is electrically isolated from the pins. In addition, the plate 230 together with the middle chuck assembly element 182 defines vacuum paths.
While making high voltage measurements the air between two conductors will break down, e.g., arc, if the conductors are sufficiently close together. For example, when testing at 5000 volts the spacing between conductors should be in excess of about 0.2 inches. Referring to
After further consideration another factor impacting rigidly is the interconnecting materials themselves. Preferably, the conductive member is at least three times as thick as the insulating material between the adjacent chuck assembly elements, and more preferably at least six times as thick. In this manner, a major portion of the spacing material is rigid conductive material which is significantly less prone to compression than the insulating material under pressure.
After extensive testing the present inventor came to the further realization that the dielectric absorption of the dielectric material tends to drain faster when both sides of the dielectric material are in face-to-face contact with electrical conductors. In contrast, when only one side of the dielectric material is in face-to-face contact with an electrical conductor then the dielectric absorption drains slowly with changes in electrical potential and hence degrades the electrical performance. Accordingly, referring to
The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7969173||Oct 23, 2007||Jun 28, 2011||Cascade Microtech, Inc.||Chuck for holding a device under test|
|US8319503||Nov 16, 2009||Nov 27, 2012||Cascade Microtech, Inc.||Test apparatus for measuring a characteristic of a device under test|
|US8698099 *||Sep 30, 2010||Apr 15, 2014||Kyocera Corporation||Attraction member, and attraction device and charged particle beam apparatus using the same|
|US20110073776 *||Mar 31, 2011||Kyocera Corporation||Attraction member, and attraction device and charged particle beam apparatus using the same|
|U.S. Classification||324/756.01, 279/3, 279/158, 324/762.05|
|International Classification||H01L21/66, H01L21/68, G01R31/26, H01L21/683, G01R1/06, B23B31/30, G01R31/28, G01R31/02|
|Cooperative Classification||Y10T279/11, Y10T279/35, H01L21/68785, G01R31/2887|
|European Classification||G01R31/28G5B, H01L21/687S20|
|Oct 23, 2007||AS||Assignment|
Owner name: CASCADE MICROTECH, INC., OREGON
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DUNKLEE, JOHN;REEL/FRAME:020055/0582
Effective date: 20010510