Multi-layer probes having longitudinal axes and preferential probe bending axes that lie in planes that are nominally parallel to planes of probe layers

Abstract

Embodiments are directed to probes formed from multiple layers with at least a portion of the layers forming elastically compliant portions of the probes wherein portions of different layers are formed of different materials and wherein a plane of a preferred elastic deformation of the probes is parallel to a plane containing (a) a normal to the planes of the layers and (b2) a longitudinal axes of the probes or a local longitudinal axes of the probes.

Description

MULTI-LAYER PROBES HAVING LONGITUDINAL AXES AND PREFERENTIAL PROBE BENDING AXES THAT LIE IN PLANES THAT ARE NOMINALLY PARALLEL TO PLANES OF PROBE LAYERSField of the Invention:

[0001] The present disclosure relates generally to the field of probes for making contact with electronic devices, e.g. for testing those electronic devices, e.g. semiconductor devices, and more particularly to multi-layer probes having elongated configurations (e.g. longitudinally extending configurations) running parallel to the planes of the layers of the probe with a preferential bending axis (i.e. an axial direction around which an elastic portion of the probe bends, i.e. a direction substantially perpendicular to a plane through which deformation of the probe occurs) located within a plane that is nominally parallel to the planes of the probe layers wherein the preferential direction has a lower stiffness to elastic deformation or smaller thickness, than that of the probe or local portion of the probe in a direction parallel with the planes of the probe layers.Background of the Invention:

[0002] Probes of various types have been fabricated and used, or have been proposed for use, in the semiconductor testing. As the semiconductor industry continues to drive integrated circuit complexity up and size down (more transistors per unit area), a need exists for new and improved probe designs for contacting such electronic components for testing and other purposes and / or for making permanent contact with such devices and / or with other packaged and unpackaged electronic devices. This need drives probes to smaller sizes (smaller X and Z cross- sectional dimensions and sometimes to shorter lengths, or longitudinal dimensions, in Y), lower contact force, less scrubbing or more controlled scrubbing, while still maintaining high current carrying capacity so that shorts in failed semiconductor devices do not damage the probes.

[0003] A need exists for improved probes that can meet the new challenges that that advances in the semiconductor industry are driving.Summary of the Invention

[0004] It is an object of some embodiments of the invention to provide meso-scale or microscale probes with each having a preferential bending axis (i.e. an axis that is perpendicular to a plane through which deformation occurs) that lies in a plane that is nominally parallel to the planes of the probe layers or to provide probe arrays which have a plurality of probes with each probe having a preferential deflection plane which is parallel to a plane defined by a normal of theprobe layers and a deflection direction of the probe tip when making contact with an electronic component.

[0005] In some objects the probes may be vertical probes or even vertical probes configured for use with one or more guide plates.

[0006] More specifically, in a first aspect of the invention a multi-layer elongated probe for making an electrical connection comprises: a tip end comprising at least one layer; a base end comprising at least one layer; and an intermediate region comprising at least one elastically compliant region formed from materials that are different from the tip end and the base end, wherein the intermediate region connects the tip end to the base end, wherein the intermediate region is formed from at least three layers and at least two distinct materials, wherein for a plurality of pairs of adjacent layers, each pair includes a first adjacent layer and a second adjacent layer wherein a material on one of the first and second adjacent layers is different from a material on the other of the first and second adjacent layers, wherein the elastically compliant region of the probe has a preferential bending axis that extends substantially parallel to planes of the layers when subjected to a compressive force between the base end and the tip end, wherein the probe is defined by a notch in the at least one elastically compliant region on a side of the probe that provides for preferential bending of the probe such that the at least one elastically compliant region bulges to another side of the probe.

[0007] The prior art does not disclose nor suggest an intermediate region including at least one elastically compliant region formed from materials that are different from the tip end and the base end; on the contrary, the known art shows an intermediate region formed from materials that are the same as the tip and the base. Moreover, nowhere in the prior art it is disclosed a probe defined by a notch in the at least one elastically compliant region on a side of the probe that provides for preferential bending of the probe such that the at least one elastically compliant region bulges to another side of the probe.

[0008] Other objects and advantages of various embodiments of the invention will be apparent to those of skill in the art upon review of the teachings herein. The various embodiments of the invention, set forth explicitly herein or otherwise ascertained from the teachings herein, may address one or more of the above objects alone or in combination, or alternatively may address some other object ascertained from the teachings herein. It is not necessarily intended that allobjects be addressed by any single aspect of the invention even though that may be the case regarding some aspects.

[0009] Numerous variations of the first aspect of the invention are possible and include, for example: (1 ) the electrical connection being selected from the group consisting of: (a) a temporary connection for wafer level testing of a semiconductor device; (b) a temporary connection for testing an electronic component comprising a diced semiconductor device; (c) a temporary connection for an electronic component comprising a packaged semiconductor device; (d) a permanent connection for testing an electronic component comprising a diced semiconductor device; and (e) a permanent connection for an electronic component comprising a packaged semiconductor device; (2) each of a plurality of layers of the probe having a substantially uniform thickness in a layer stacking direction across their widths and lengths and a ratio of a longitudinal length of the probe to a thickness of the elastically compliant region of the probe in a layer stacking direction being selected from the group consisting of (a) > 40, (b) > 60, (c) > 80, (d) > 100, and (e) > 120 and wherein a ratio of a longitudinal length of the probe is to a width of the elastically compliant region of the probe perpendicular to a layer stacking direction being selected from the group consisting of (a) > 40, (b) > 60, (c) > 80, (d) > 100, and (e) > 120; (3) the layers being planar; (4) the probe having a curvature in width along at least a portion of its length; (5) the probe having a stepped structure, or stepped curvature, in a layer stacking direction along at least a portion of its length; (6) the probe being formed as a linear structure; (7) the probe including at least one curved planar region in its elastic region; (8) the at least three layers being at least four layers; (9) the at least three layers being at least five layers; (10) the at least three layers being at least seven layers; (11 ) a thickness of the elastically compliant portion of the probe in a stacking direction of the layers being less than a width of the elastically compliant portion of the probe within the planes of the layers; (12) a thicknesses of solid material of the elastically compliant portion of the probe less a thickness of any gaps in the solid material in the stacking direction of the layers being less than a total width of solid material less the width of any gaps in material of the elastically compliant portion of the probe within the planes of the layers; (13) the preferential bending axis being based, at least in part, on the thickness of probe in the layer stacking direction in the elastically compliant region being less than a width of the probe; (14) the preferential bending axis being based, at least in part, on a thicknesses of solid material of the elastically compliant portion of the probe less a thickness of any gaps in the solid material in the stacking direction of the layers being less than a total width of solid material less the width of any gaps in material of the elastically compliant portion of the probe within the planes of the layers; (15) the material forming the elastically complaint portion includes a stiffer material (i.e. a material with a higher yield strength) as part of outer probelayers relative to at least one inner layer (i.e. a layer between the outer probe layers); (16) the tip region of the probe including at least one material as part of at least one layer that has a higher yield strength than any material of the elastically compliant portion of outer probe layers; (17) the base region of the probe including at least one material as part of at least one layer that has a higher yield strength than any material of the elastically compliant portion of outer layers; (18) the probe being a vertical probe; and (19) combinations of the above noted variations so long as the combination does not completely remove the benefit of one or more of the combined variations.

[0010] In a second aspect of the invention a probe array includes a plurality of multi-layer elongated probes for making an electrical connection, the probe array comprising: (a) a plurality of probes, with each probe comprising: (i) a base end comprising at least one layer; and (ii) an intermediate region comprising at least one elastically compliant region formed from materials that are different from the tip end and the base end, wherein the intermediate region connects the tip end to the base end and wherein the intermediate region is formed from at least three layers and at least two distinct materials wherein for a plurality of pairs of adjacent layers, each pair includes a first adjacent layer and a second adjacent layer wherein a material on one of the first and second adjacent layers is different from a material on the other of the first and second adjacent layers and wherein the probe is defined by a notch in the at least one elastically compliant region on a side of the probe that provides for preferential bending of the probe such that the at least one elastically compliant region bulges to another side of the probe; (b) at least one guide plate for aligning at least one of the top or bottoms of probes in a desired array configuration wherein at least one end of each probe, when held by the guide plate, is capable of movement along an axis when contacted to an electronic component, wherein the elastically compliant region of a plurality of the probes have preferential configurations, when held by the at least one guide plate, to bend in a plane that includes a normal of the multiple layers of each respective probe and the axis of movement of the respective probe when contacted to the electronic component.

[0011] Numerous variations of the second aspect of the invention are possible and include, for example: (1 ) variations similar to those noted for the first aspect; (2) use of different numbers of probes; (2) use of probes with one or more different configurations; (3) probes arranged in linear arrays; (4) probes arranged in areal arrays; (5) probes with different elastic compliances; (6) probes with different bending directions; (7) probes formed of different materials; (8) materials of probes alternating between two or more materials from successive layer to successive layer; (9) probes with more than one material forming part of a single layer: (9) probes with contact tips on both the base end and the tip end; and (10) probes with elastic complaint regions comprising a plurality of beams joined on either end.

[0012] Other aspects of the invention will be understood by those of skill in the art upon review of the teachings herein. Other aspects of the invention may involve combinations of the above noted aspects of the invention. These other aspects of the invention may provide various combinations of the aspects presented above as well as provide other configurations, structures, functional relationships, and processes that have not been specifically set forth above but are taught elsewhere herein.Brief Description of the Drawings:

[0013] FIG. 1 A provides a side view of an example elongated probe having a longitudinal axis extending in Y, with layers stacked in Z, and with a width of the probe extending in X wherein the probe is formed in a straight configuration (uncurved).

[0014] FIG. 1 B provides a side view of the probe of FIG. 1 A after the probe has been subjected to sources of stress.

[0015] FIGS. 1 C-1 , 1 C-2 and 1C-3 provide blown up views of regions of the probe of FIG. 1 B wherein each of three layers forming the probe can be seen and wherein the stress on one layer is relatively low while the stresses on the other layers are higher.

[0016] FIGS. 1 D-1 and 1 D-2 show blown up views of the tip end and base end of the probe, respectively, rotated 90°.

[0017] FIGS. 2A - 20 show blown up views of the tip and base ends as well as an intermediate portion of a sample probe according to some embodiments of the invention.

[0018] FIG. 3A is a side view of three sample probes that may be used in forming a probe array similar to those illustrated in FIGS. 3B and 30.

[0019] FIG. 3B is a side view of a probe array comprising the probe array of FIG. 3A.

[0020] FIG. 30 is a side view of a the probe array of Fig. 3B in a different working condition.

[0021] FIGS. 4A - 4D illustrate four alternative embodiments of the probes according to the invention.Detailed Description of Preferred Embodiments:

[0022] Multi-layer, multi-material electrochemical fabrication methods may be used in fabricating probes according to some embodiments of the invention. Some such methods may use photoresist or other dielectric materials as sacrificial materials as opposed to the metal materials of the primary embodiments of the above noted patents. Other methods may also be used in fabricating the probes of various embodiments of the present invention some such methods are set forth in the various other patents and applications referenced herein.

[0023] Definitions

[0024] This section of the specification is intended to set forth definitions for a number of specific terms that may be useful in describing the subject matter of the various embodiments of the invention. It is believed that the meanings of most if not all of these terms is clear from their general use in the specification but they are set forth hereinafter to remove any ambiguity that may exist. It is intended that these definitions be used in understanding the scope and limits of any claims that use these specific terms. As far as interpretation of the claims of this patent disclosure are concerned, it is intended that these definitions take presence over any contradictory definitions or allusions found in any materials.

[0025] “Build” as used herein refers, as a verb, to the process of building a desired structure (or part) or plurality of structures (or parts) from a plurality of applied or deposited materials which are stacked and adhered upon application or deposition or, as a noun, to the physical structure (or part) or structures (or parts) formed from such a process. Depending on the context in which the term is used, such physical structures may include a desired structure embedded within a sacrificial material or may include only desired physical structures which may be separated from one another or may require dicing and / or slicing to cause separation.

[0026] “Build axis” or “build orientation” is the axis or orientation that is substantially perpendicular to substantially planar levels of deposited or applied materials that are used in building up a structure. The planar levels of deposited or applied materials may be or may not be completely planar but are substantially so in that the overall extent of their cross-sectional dimensions are significantly greater than the height of any individual deposit or application of material (e.g. 100, 500, 1000, 5000, or more times greater). The planar nature of the deposited or applied materials may come about from use of a process that leads to planar deposits or it may result from a planarization process (e.g. a process that includes mechanical abrasion, e.g. lapping, fly cutting, grinding, or the like) that is used to remove material regions of excess height. Unless explicitly noted otherwise, “vertical” as used herein refers to the build axis or nominal build axis (if the layers are not stacking with perfect registration) while “horizontal” refers to a direction within the plane of the layers (i.e. the plane that is substantially perpendicular to the build axis).

[0027] “Build layer” or “layer of structure” as used herein does not refer to a deposit of a specific material but instead refers to a region of a build located between a lower boundary level and an upper boundary level which generally defines a single cross-section of a structure being formed or structures which are being formed in parallel. Depending on the details of the actual process used to form the structure, build layers are generally formed on and adhered to previously formed build layers. In some processes the boundaries between build layers are defined byplanarization operations which result in successive build layers being formed on substantially planar upper surfaces of previously formed build layers. In some embodiments, the substantially planar upper surface of the preceding build layer may be textured to improve adhesion between the layers. In other build processes, openings may exist in or be formed in the upper surface of a previous but only partially formed build layers such that the openings in the previous build layers are filled with materials deposited in association with current build layers which will cause interlacing of build layers and material deposits. In most embodiments, a build layer includes at least one primary structural material and at least one primary sacrificial material. However, in some embodiments, two or more primary structural materials may be used without a primary sacrificial material (e.g. when one primary structural material is a dielectric and the other is a conductive material). In some embodiments, build layers are distinguishable from each other by the source of the data that is used to yield patterns of the deposits, applications, and / or etchings of material that form the respective build layers. For example, data descriptive of a structure to be formed which is derived from data extracted from different vertical levels of a data representation of the structure define different build layers of the structure. The vertical separation of successive pairs of such descriptive data may define the thickness of build layers associated with the data. As used herein, at times, ‘‘build layer” may be loosely referred simply as "layer”. In many embodiments, deposition thickness of primary structural or sacrificial materials (i.e. the thickness of any particular material after it is deposited) is generally greater than the layer thickness and a net deposit thickness is set via one or more planarization processes which may include, for example, mechanical abrasion (e.g. lapping, fly cutting, polishing, and the like) and / or chemical etching (e.g. using selective or non-selective etchants). The lower boundary and upper boundary for a build layer may be set and defined in different ways. From a design point of view they may be set based on a desired vertical resolution of the structure (which may vary with height). From a data manipulation point of view, the vertical layer boundaries may be defined as the vertical levels at which data descriptive of the structure is processed or the layer thickness may be defined as the height separating successive levels of cross-sectional data that dictate how the structure will be formed. From a fabrication point of view, depending on the exact fabrication process used, the upper and lower layer boundaries may be defined in a variety of different ways. For example by planarization levels or effective planarization levels (e.g. lapping levels, fly cutting levels, chemical mechanical polishing levels, mechanical polishing levels, vertical positions of structural and / or sacrificial materials after relatively uniform etch back following a mechanical or chemical mechanical planarization process). For example, by levels at which process steps or operationsare repeated. At levels at which, at least theoretically, lateral extends of structural material can be changed to define new cross-sectional features of a structure.

[0028] “Layer thickness” is the height along the build axis between a lower boundary of a build layer and an upper boundary of that build layer.

[0029] “Structural material” as used herein refers to a material that remains part of the structure when put into use.

[0030] Some embodiments of the present disclosure are directed to vertical probes or pin probes. These probes may be formed with their longitudinal axes (i.e. tip-to-tip axes, tip-to-tip heights, base-to-tip axes, or base-to-tip heights) oriented perpendicular to a layer stacking axis or layer surface normal when being formed from a single layer or from the buildup of a plurality of layers (i.e. with their longitudinal axes being oriented parallel to the lateral extents of a layer or layers from which the probe is formed). Alternatively, the longitudinal axes of the probes may be formed parallel to a stacking axis of the layers or at some other angle between parallel and perpendicular to the stacking axis of the layers. Unlike cantilever probes, vertical probes typically have longitudinal extents (e.g. heights in Z) that are much greater than their lateral extends (e.g. widths in X and Y). For example, the ratio of height to maximum width for vertical probes may be in range from 5 / 1 or 10 / 1 to 100 / 1 or more. Unlike cantilever probes, vertical probes can be arranged into two-dimensional arrays with close packing, or pitch, in both X and Y directions simultaneously. As used herein, nominal pitch or minimum pitch is the closest, used or useable, tip-to-tip spacing of two adjacent similar probes that are similarly oriented. A packing ratio, PR (minimum or nominal pitch) of acceptable tip-to-tip spacing of adjacent vertical probes in X (to acceptable tip-to-tip vertical probe spacing in Y may be within 1 / 5 and 5, i.e. 1 / 5 <= PR <= 5, and is often within 1 / 2 to 2, and in practice is believed to often be within a 0.9 to 1.1 packing ratio). In many vertical probe arrays, the tip-to-tip spacing between probes in X is less than 5 times the width of the probe in X, i.e. the spacing / width ratio is less than about five, and similarly the spacing between probes in Y is less than about 5 times the width of the probe in Y. The spacing to width ratio in both X and Y is often less than 3 and is often about 2 or less.

[0031] Various embodiments of the invention provide probes that bend preferentially along paths that are oriented perpendicular to the planes that contain the layers of the probes and that are parallel to the longitudinal axes of the probes. In some embodiments, probes may twist upon bending but the primary path of movement of the compliant portion of the probe is in a plane including a plane through defined by a local longitudinal axis of the probe and a perpendicular to the planes of the layers. In some embodiments the probes are formed as linear structures and provided with a pre-bent configuration upon array formation while in other embodiments the probesare formed with a pre-bent or stair stepped configuration that provides for, at least in part, a preferential bending axis which is perpendicular to a plane in which bending occurs, while in still other embodiments a combination of bent or stair stepped formation in combination with prebending during array formation are used.

[0032] FIG. 1 A is a side view of an example elongated probe 100 having a longitudinal axis extending in Y, with layers stacked in Z, and with a width of the probe 100 extending in X wherein the probe is formed in a straight configuration (uncurved). FIG. 1 A also provides examples constraints (01-03) that may be placed on the probe 100 when held in guide plates and when subject to longitudinal compressive forces (F1 -F2) when making contact with an electronic device that is, for example, under test (i.e. a DUT).

[0033] More particularly, the probe 100 may be subjected to a first constraint C1 and a second constraint C2 due to the guide plates provided with corresponding guide hole slindingly housing the probe 100. A further third constraint C3 may be due to the sliding of a tip end 101 of the probe 100, in particular on a contact pad of a device under test (not shown). Also, a fourth constraint 04 may be due to displacement control load at the distal end or base end 102 of the probe 100. An intermediate region 103 connects the tip end 101 to the base end 102 of the probe 100 and comprises an elastically compliant region 120.

[0034] FIG. 1 B is a side view of the probe of FIG. 1 A after the probe 100 has been subjected to sources of constraint and stress including: (a) preloading constraints and stress that displaces the tip end 101 and base end 102 of the probe in the Z direction as the probe might exist after being loaded into a set of guide plates, and (b) loading stress that results from the tip end 101 of the probe 100 being pressed along the Y axis by a contact surface of an electronic device which cause a Y-direction displacement and compression of the probe when the base end 102 is contacted with a surface of a second electronic component, such as a PCB or space transformer, which results in a bending or bulging of the intermediate region 103 of probe along the negative Z axis, in this example, to compensate for the compression that is forced to occur in Y. The probe100 has a length L100 along the Y axis and a width W100 along the Z axis.

[0035] FIGS. 1 C-1 , 1 C-2 and 1C-3 show blown up views of regions S1 , S2 and S3 of the probe 100 of FIG. 1 B. More particularly, FIG. 1 C-1 shows a first or top region S1 of the intermediate region 103 of the probe 100, FIG 1 C-2 shows a second or middle region S2 of the intermediate region 103 of the probe 100 and FIG 1 C-3 shows a third or bottom region S3 f the intermediate region 103 of the probe 100, each region being formed by a first layer 1 11 , a second or middle layer 112 and a third layer 1 13.

[0036] Suitably, as shown in FIGS. 1 C-1 , 1C-2 and 1 C-3, the stress on the middle layer 112 is relatively low while the stresses on the first layer 1 11 and third layer 113 are higher and particularly on the outside portions of the layers (i.e. left most portion of the first layer 11 1 being on the left and right most portion of the third layer 113 being on the right in the figures where displacement from a neutral line (e.g. a center portion of the middle layer 112) is largest and where curvature is highest (i.e. radius of curvature is smallest). In other embodiments with different probe widths, different layer thicknesses, different number of layers, different variations in cross- sectional width or thickness, different probe lengths, different preloading stresses, and / or different “as formed” configurations, will result in different ultimate probe curvatures and different stress distributions.

[0037] FIGS. 1 D-1 and 1 D-2 show two blown up views of the distal or base end and of the tip end of a probe rotated 90° so that the width of an example probe according to X axis can be seen.

[0038] Suitably, a thickening of the width (along the X axis) of the design of the probe 100 may be provided in regions of high stress. More particularly, as shown in FIGS. 1 D-1 and 1 D-2, the probe 100 comprises thickened regions T1 and T2 where the probe 100 interacts with a guide plate, having respective widths W1 and W3 (i.e. sizes along X axis). A first thickened region T 1 is in particular provided between the base end 102 and the intermediate region 103 of the probe 100, as shown in FIG. 1 D-1 and a second thickened region T2 is provided between the intermediate region 103 and the tip end 101 of the probe 100. More particularly, the intermediate region 103 has a third width W3 along the X axis, being also the width of the elastically compliant portion 120 defined therein. Suitably, as shown in FIGS. 1 D-1 and 1 D-2, the first width W1 is greater than the third width W3 and the second width W2 is greater than the third width W3. In a preferred embodiment, the first width W1 and the second width W2 have a same value, which is 1 -20 microns, preferably 2 microns, more than the value of the third width W3. For example, W1 =W2=0,043 millimeters and W3=0,041 millimeters.

[0039] In this way, stress and bending of the probe 100 are shifted to other portions along the probe length, different from such regions of high stress.

[0040] In other embodiments uniform cross-sectional widths may be used along the entire probe length L100 or along the elastically compliant portion 120 of the probe 100, variations in size other than the 2 micron variation shown (from 0.041 to 0.043 millimeters) may be used. For example, the variation may be as small as 1 micron or less or as much as 5, 10 or even 20 microns or more. In some embodiments depending on the materials being used the total thickness of the layers forming the elastically compliant section 120 of the probe 100 may be considerably less thanthe widths shown in FIGS. 1 D-1 and 1 D-2 or they may be slightly less, approximately the same or even slightly larger. In some embodiments, the thickness of the layers and the width of the layers will be selected, based on the materials being used, such that a bending moment within the plane of the layers is larger than a bending moment that is in the direction of the layer normal such that preferential bending will occur in the direction of the layer normal when the probe is subject to compressive forces on its tip and base.

[0041] FIGS. 2A - 2C show blown up views of the tip end 101 , the middle or intermediate region 103, and the distal or base end 102 of a sample probe 100, respectively according to some embodiments of the invention, where the probe 100 is formed from up to five layers.

[0042] More particularly, as shown in FIGS. 2A and 2B, a first layer 1 11 , a second layer112 and a third layer 113 form both the tip end 101 and the base end 102 as well as the elastically compliant portion 120 of the intermediate region 103 (i.e. the body) of the probe 100. The base end 102 is also formed by the first layer 111 , second layer 1 12 and third layer 1 13 and further comprises s first additional layer 140a and a second additional layer 140a in a portion of the base end 102 which is adapted to be held within probe holes in a guide plate housing the probe 100, the additional layers 140a, 140b forming a guide plate stop 100 of the probe 100, as shown in FIG. 2C.

[0043] In some variations the one layer, e.g. the center or second layer 1 12 may extend beyond the other layers to from a finer contact region on one or both of the tip end 101 and the base end 102.

[0044] In some alternative embodiments, the probe may take on non-linear configurations as formed, may have no stops, may have stops in different locations, may have varying width or thickness, may take on linear or non-linear configurations when loaded into guide plates or mounted to a substrate, may use different materials other the palladium-gold-palladium stack of materials as set forth in the this example, may include use of a different tip material on one or both ends (e.g. a higher yield strength material or a more abrasion resistant material), or may be formed from a different number of layers along with different combinations of material stacks.

[0045] In some embodiments, a higher yield strength material (e.g. palladium) is located at the portions of the probe (e.g. layers or layer portions) that undergo higher stress while a lower yield strength material (e.g. gold) may be preferentially located or limited to locations where the stress is lower. In particular it is preferable that the stress experienced by each portion of the probe is less than a yield strength of that portion of the probe (more preferably less than 80% of the yield strength or even 50% of the yield strength, or even less under the given operating conditions so as to limit potential for permanent probe deformation (e.g. creep) or breakage as aresult of loading while still providing improved current carrying capacity by using a higher conductivity material (e.g. gold, silver, or copper) in regions of lower stress).

[0046] Suitably, according to an embodiment of the invention, the material forming the elastically compliant portion 120 may comprise a stiffer material as part of outer probe layers (i.e. layers 111 , 113) relative to at least one inner layer (i.e. layer 112).

[0047] Moreover, the tip end 101 of the probe 100 may comprise at least one material as part of at least one layer that has a higher yield strength than any material of outer probe layers at the elastically compliant portion 120 and the base end 102 of the probe 100 may comprise at least one material as part of at least one layer that has a higher yield strength than any material of the outer layers at the elastically compliant portion 120.

[0048] FIG. 3A shows side views of three sample probes 100 that may be used in forming an array of probes 300 similar to those illustrated in FIGS. 3B and 3C where upon formation the probe 100 may be linear in configuration (left most probe 100A), may have a bent configuration or stepped configuration (i.e. in a layer stacking direction Z in this example or in the planes of the layers in an alternative embodiment) where the amount of bending or stair stepping is less than an amount of bending which will exist in an uncompressed probe array (middle probe 100B), or may have a bent or stair stepped configuration (i.e. in a layer stacking direction Z of this example) which matches that of the bending that will exist in the probes while in an uncompressed array configuration (right most probe 100C) and wherein in this example each probe variation has a similar length.

[0049] FIG. 3B provides a side view of a probe array 300 while the probes 100 are in contact with an upper contact element 350 (such as a space transformer of a probe head) but while the probes 100 are not in a longitudinally compressed state as no contact is yet made with an electronic component 340 (such as a device under test) below the array 300.

[0050] FIG. 3C provides an example side view of a probe array 300 in a different working condition, while the probes 100 are in contact with the upper contact element 350 and are also compressed by contact with the electronic component 340 wherein additional deflection of the probes 100, in a preferential bending direction BD, can be seen as a result of contact with the electronic component 340 and the relative compression of the probes 100 of the probe array 300.

[0051] As shown in FIGS. 3B and 3C, the probes 100 are slidingly housed in guide holes (not shown) provided in a first guide plate 310 and a second guide plate 320, duly connected by means of a case 330. More particularly, the first guide plate 310 is adapted to align the tip ends 101 of the probes 100 and the second guide plate 320 is adapted to align the base ends 102 of the probes 100 in a desired array configuration, the probes 100 being capable of movement along anaxis (Y in the figures) when contacted to the electronic component 340, according to the so called overtravel OT.

[0052] FIGS. 4A - 4D illustrate four alternative embodiments where the probes 100 take on non-linear configurations in the layer stacking direction Z and where material forming successive layers alternates from one material M1 (e.g. Pd or NiCo) to another material M2 (e.g. Au, Ag, or Cu).

[0053] Moreover, the probes 100 comprise respective contact extensions provided at each end of the probe, in particular a first contact extension 101 a at the tip end 101 and a second contact extension 102a at the base end 102, where each contact extension 101 a, 102a includes a different material M3 (e.g. rhodium) than that of the elastically compliant portions 120 of the probes 100

[0054] FIG. 4A illustrates an example probe with a notch 130 in a central region of the elastically compliant portion 120 on the side PS1 , in particular a left side of the 100 probe which provides for preferential bending with the elastically compliant portion 120 bulging to another side PS1 , in particular the right side.

[0055] In particular, the preferential bending axis is based, at least in part, on the thickness Th120 of probe 100 in the layer stacking direction Z at the elastically compliant portion 120 being less than a width W100 of the probe 100.

[0056] FIG. 4B illustrates an example probe with a lower end, i.e. the tip end 101 , offset, in particular to the right, relative to the upper end, i.e. the base end 102. In particular, the probe 100 comprises a first layer 101 , a second layer 102, a third layer 103, a fourth layer 104, a fifth layer 105, a sixth layer 106 and a seventh layer 107, stacked along the Z axis and having different lengths along the longitudinal axis Y so that the probe 100 has a stepped configuration with the tip end 101 offset relative to the base end 102.

[0057] The probe 100 of FIG. 4B also comprises a notch 130 at a central region of the elastically compliant portion 120 and a preferential bending axis is defined being, at least in part, based on the thickness Th 120 of the elastically compliant portion 120 in the layer stacking direction Z being less than the width W100 of the probe 100.

[0058] FIG. 4G illustrates an example probe with a more distinct C-shaped elastically compliant portion 120 with a shifting of a central portion of the probe to the right relative to the probe ends. In particular, the probe 100 comprises a first layer 101 , a second layer 102, a third layer 103, a fourth layer 104, a fifth layer 105, a sixth layer 106 and a seventh layer 107, stacked along the Z axis and having different lengths along the longitudinal axis Y so that the probe 100 has a C-shaped elastically compliant portion 120.

[0059] The probe 100 of FIG. 4C also comprises a notch 130 at a central region of the elastically compliant portion 120, so that a preferential bending axis is defined due to the thickness of the elastically compliant portion 120 being less than the width of the probe 100.

[0060] FIG. 4D illustrates an example probe with an S-shaped elastically compliant portion 120, defined by means of a plurality of layers, suitably sized an positioned.

[0061] The probe 100 of FIG. 4D comprises a fist notch 130a and a second notch 130b symmetrically positioned with respect to a central region of the elastically compliant portion 120.

[0062] Other probe shape variations in the layer stacking direction are possible and will be apparent to those of skill in the art upon review of the teachings herein. In still other embodiments a combination of shape variations in the layer stacking direction may exist along with curved or stair-stepped variations within individual layers. In still other variations not all layers need to have be formed with alternating materials (e.g. compliant portions of the probe on some successive layers may be formed of the same material or a combination of materials while in other embodiments more than two materials may be alternated). In still other embodiments, one of the compliant materials may act as a contact material. In still other embodiments some layers may be formed with dielectrics (e.g. for ensuring electrical isolation between adjacent probes or for ensuring electrical isolation between two conductive paths on a single probe). In some embodiments, probes may have a contact tip on one end and be configured for bonding to a circuit element on the other end as opposed to having two contact tips. Some probes may include materials to aid in bonding while other probes may include materials in selected side-facing regions that allow for wear resistant sliding contact with a guide plate or the other array supporting structure.

[0063] In conclusion, probe structures may take on a variety of different configurations, be formed using different processes, and be made to contain a variety of different materials to improve overall probe and array functionality. Some embodiments may form probes using selective deposition processes or blanket deposition processes on some layers that are not electrodeposition processes. Some probes may be formed using aligned, stacked and bonded preformed sheets of material alone or in combination with dispensed materials. Sheets may be subjected to laser cutting before stacking (if probe cross-sections remain in position by a bridging layer or by tethering) or after stacking and bonding. Bonded sheets may be subject to blanket or selective material deposition when additional materials are to be incorporated wherein such deposition may occur before or after any machining of the sheet material. Some embodiments may use nickel as a structural material while other embodiments may use different materials. For example, preferred spring materials include nickel (Ni), beryllium copper (Be-Cu), nickelphosphorous (Ni-P), titanium (Ti), tungsten (W), aluminum copper (Al-Cu), steel, Paliney 7 (Pd-Ag- Au-Pt) alloy, palladium (Pd), molybdenum (Mo), manganese (Mn), chrome or chromium (Cr), chromium copper (Cr-Cu), and combinations of these. Materials for enhanced current carrying capacity may for example include copper (Cu), silver (Ag), or gold (Au). Materials for use on contact or interface surfaces may have enhanced abrasion resistance or other properties and may, for example, include the spring materials noted above and may, for example, additionally or alternatively include materials such as rhodium (Rh), rhenium (Re), tungsten carbide (W-C), and palladium gold alloys (Pd-Au).

[0064] Structural or sacrificial dielectric materials may be incorporated into embodiments of the present invention in a variety of different ways. Such materials may form a third material or higher deposited material on selected layers or may form one of the first two materials deposited on some layers.

[0065] Some embodiments may employ diffusion bonding or the like to enhance adhesion between successive layers of material. Various teachings concerning the use of diffusion bonding in electrochemical fabrication processes are known in the field.

[0066] It will also be understood by those of skill in the art that the probe elements of some aspects of the invention may be formed with processes which are very different from the processes set forth herein, and it is not intended that structural aspects of the invention need to be formed by only those processes taught herein or by processes made obvious by those taught herein.

[0067] Though various portions of this specification have been provided with headers, it is not intended that the headers be used to limit the application of teachings found in one portion of the specification from applying to other portions of the specification. For example, alternatives acknowledged in association with one embodiment, are intended to apply to all embodiments to the extent that the features of the different embodiments make such application functional and do not otherwise contradict or remove all benefits of the adopted embodiment. Various other embodiments of the present invention exist. Some of these embodiments may be based on a combination of the teachings set forth herein with various teachings.

[0068] It is intended that the aspects of the invention set forth herein represent independent invention descriptions which Applicant contemplates as full and complete invention descriptions that Applicant believes may be set forth as independent claims without need of importing additional limitations or elements, from other embodiments or aspects set forth herein, for interpretation or clarification other than when explicitly set forth in such independent claims once written. It is also understood that any variations of the aspects set forth herein represent individual and separate features that may form separate independent claims, be individually added to independent claims,or added as dependent claims to further define an invention being claimed by those respective dependent claims should they be written.

[0069] In view of the teachings herein, many further embodiments, alternatives in design and uses of the embodiments of the instant invention will be apparent to those of skill in the art. As such, it is not intended that the invention be limited to the particular illustrative embodiments, alternatives, and uses described above but instead that it be solely limited by the claims presented hereafter, subsequently amended, or subsequently set forth in an application that claims priority to this application.

Claims

CLAIMS1 . A multi-layer elongated probe (100) for making an electrical connection, the probe comprising: a tip end (101 ) comprising at least one layer; a base end (102) comprising at least one layer; and an intermediate region (103) comprising at least one elastically compliant portion (120) formed from materials that are different from the tip end (101 ) and the base end (102), wherein the intermediate region (103) connects the tip end (101) to the base end (102), wherein the intermediate region (103) is formed from at least three layers (111 , 112, 113) and at least two distinct materials (M1 , M2), wherein for a plurality of pairs of adjacent layers (11 1 , 1 12, 1 13), each pair includes a first adjacent layer (11 1 , 112) and a second adjacent layer (112, 113) wherein a material (M1) on one (1 11 , 1 13) of the first and second adjacent layers (111 , 112, 113) is different from a material (M2) on the other (112) of the first and second adjacent layers (1 11 , 1 12, 1 13), wherein the elastically compliant portion (120) of the probe (100) has a preferential bending axis that extends substantially parallel to planes of the layers (11 1 , 112, 113) when subjected to a compressive force between the base end (102) and the tip end (100), wherein the probe (100) is defined by a notch (130) in the at least one elastically compliant region (120) on a side (PS1 ) of the probe (100) that provides for preferential bending of the probe (100) such that the at least one elastically compliant portion (120) bulges to another side (PS2) of the probe (100).

2. The probe of claim 1 wherein the electrical connection is selected from the group consisting of: (1 ) a temporary connection for wafer level testing of a semiconductor device; (2) a temporary connection for testing an electronic component comprising a diced semiconductor device; (3) a temporary connection for an electronic component comprising a packaged semiconductor device; (4) a permanent connection for testing an electronic component comprising a diced semiconductor device; and (5) a permanent connection for an electronic component comprising a packaged semiconductor device.

3. The probe of claim 1 wherein each of a plurality of layers (11 1 , 112, 113) of the probe (100) has a substantially uniform thickness in a layer stacking direction (Z) across its width and length, and a ratio of a longitudinal length (L100) of the probe (100) to a thickness (Th 120) of the elastically compliant portion (120) of the probe (100) in a layer stacking direction (Z) is selectedfrom the group consisting of (1 ) = > 40, (2) => 60, (3) => 80, (4) => 100, and (5) => 120 and wherein a ratio of a longitudinal length (L100) of the probe (100) to a width (W3) of the elastically compliant portion (120) of the probe (100) perpendicular to a layer stacking direction (Z) is selected from the group consisting of (1 ) => 40, (2) => 60, (3) => 80, (4) => 100, and (5) => 120.

4. The probe of claim 3 wherein the layers (111 , 112, 113) are planar.

5. The probe of claim 3 wherein the layers (111 , 112, 113) have discontinuities, curvature, or changes in width along at least a portion of a longitudinal length (L100) of the probe (100).

6. The probe of claim 3 wherein the probe (100) has a stair stepped configuration in a layer stacking direction (Z) along at least a portion of a longitudinal length (L120) of the elastically compliant portion (120) of the probe (100).

7. The probe of claim 3 wherein the probe (100) has a stair stepped configuration in a layer stacking direction (Z) along at least a portion of a longitudinal length (L120) of the elastically compliant portion (120) of the probe (100) due to at least two consecutive layers (11 1 , 112; 112, 113) having different cross-sectional configurations at the elastically compliant portion (120) of the probe (100) .

8. The probe of claim 1 wherein the probe (100) is formed as a linear structure.

9. The probe of claim 1 further comprising at least a fourth layer (114) or a fifth layer (1 15).

10. The probe of claim 9 further comprising at least a sixth layer (116) and at least a seventh layer (117).11 . The probe of claim 1 wherein the preferential bending axis is based, at least in part, on the thickness (Th120) of the probe (100) in the layer stacking direction (Z) at the elastically compliant portion (120) being less than a width (W100) of the probe (100).

12. The probe of claim 1 wherein the material forming the elastically compliant portion (120) comprises a stiffer material as part of outer probe layers relative to at least one inner layer.

13. The probe of claim 1 wherein the tip end (101 ) of the probe (100) comprises at least one material as part of at least one layer that has a higher yield strength than any material of outer probe layers at the elastically compliant portion (120).

14. The probe of claim 1 wherein the base end (102) of the probe (100) comprises at least one material as part of at least one layer that has a higher yield strength than any material of the outer layers at the elastically compliant portion (120).

15. The probe of claim 1 wherein the tip end (101 ) of the probe (100) is offset with respect to the base end (102) in the layer stacking direction (Z).

16. The probe of claim 1 wherein the elastically compliant portion (120) has a shape chosen between a C-shape and a S-shape.

17. A probe array (300) comprising a plurality of multi-layer elongated probes (100) for making an electrical connection, the probe array comprising:(a) a plurality of probes, with each probe (100) comprising:(i) a tip end (101 ) comprising at least one layer;(ii) a base end (102) comprising at least one layer; and(iii) an intermediate region (103) comprising at least one elastically compliant region (120) formed from materials that are different from the material forming the tip end (101 ) and the base end (102) of the probe (100), wherein the intermediate region (103) connects the tip end (101) to the base end (102) and wherein the intermediate region (103) is formed from at least three layers (11 1 , 112, 113) and at least two distinct materials (M1 , M2) wherein for a plurality of pairs of adjacent layers (111 , 112, 113), each pair includes a first adjacent layer (1 11 , 1 12) and a second adjacent layer (1 12, 1 13) wherein a material (M1 ) on one (111 , 1 13) of the first and second adjacent layers (111 , 112, 113) is different from a material (M2) on the other (113) of the first and second adjacent layers (111 , 1 12, 1 13); and wherein the probe (100) is defined by a notch (130) in the at least one elastically compliant portion (120) on a side (PS1 ) of the probe (100) that provides forpreferential bending direction (BD) of the probe (100) such that the at least one elastically compliant portion (120) bulges to another side (PS2) of the probe (100);(b) at least one guide plate (310, 320) for aligning at least one of the tip ends (101 ) or base ends (102) of probes (100) in a desired array configuration wherein at least one tip or base end (101 , 102) of each probe (100), when held by the guide plate (310, 320), is capable of movement along an axis (Y) when contacted to an electronic component (340), wherein the elastically compliant portions (120) of the plurality of the probes (100) have preferential configurations, when held by the at least one guide plate (310, 320), to bend in a plane that includes a normal of the multiple layers (11 1 , 112, 113) forming each respective probe and the axis of movement of the respective probe (100) when contacted to the electronic component (340).

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