COMPLIANCE, AND ASSOCIATED SYSTEMS AND METHODS

CROSS-REFERENCE(S) TO RELATED APPLICATION S) This application claims the benefit of U.S. Provisional Applications

No. 62/420116, filed November 10, 2016; No. 62/454420, filed February 3, 2017; No. 62/484750, filed April 12, 2017; No. 62/485104, filed April 13, 2017; No. 62/533469, filed July 17, 2017; and No. 62/573507, filed October 17, 2017, which are hereby incorporated by reference in their entirety.

BACKGROUND

Integrated circuits are used in a wide variety of products. Integrated circuits have continuously decreased in price and increased in performance, becoming ubiquitous in modern electronic devices. These improvements in the performance/cost ratio are based, at least in part, on miniaturization, which enables more semiconductor dies to be produced from a wafer with each new generation of the integrated circuit manufacturing technology. Furthermore, the total number of the signal and power/ground contacts on a semiconductor die generally increases with new, more complex die designs.

Prior to shipping semiconductor dies to customers, the performance of the integrated circuits is tested, either based on a statistical sample or by testing each die. An electrical test of the semiconductor die typically includes powering the die through the power/ground contacts, transmitting signals to the input contacts of the die, and measuring the resulting signals at the output contacts of the die. Therefore, during the electrical test at least some contacts on the die must be electrically contacted to connect the die to sources of power and test signals.

Figures 1 A and IB are a cross-sectional view and a bottom view, respectively, of a probe card 110 for testing semiconductor wafers in accordance with prior art technology. In operation, the probe card 110 contacts a wafer 140 such that an array of probe pins 1 16 makes electrical contact with the corresponding array of die contacts 148 (e.g., pads, solderballs, copper pillars, or through-silicon-vias(TSVs)) on dies 145 (also referred to as "devices under test" or "DUTs") of the wafer. Next, a tester 150 sends electrical test sequences (e.g., test vectors) through cables 130 and the probe card 110 to the die contacts 148 of one or more dies 145 of the wafer 140. In response to these test sequences, the integrated circuits of the tested die generate output signals that are routed through the probe card 110 back to the wafer tester 150 for analysis and determination whether a particular die passes the test. Next, the test contactor is stepped onto another die or group of dies 145 that are tested in parallel, and the testing continues till the entire wafer is tested. Once the entire wafer 140 is tested, the dies on the wafer are singulated along wafer streets 146, the dies that failed the test are discarded, and the dies that passed the test are packaged and shipped to the customers.

The probe card 110 provides a path for the signal/power between the tester 150 and the dies under test 145 of the wafer 140. The signals/power pass through a printed circuit board (PCB) 114, through a contact structure 120 that connects the PCB 114 with a space transformer 112, through the routing layers 113 of a space transformer 112, and further to the probe pins 116 of the probe card 110, which, in operation, contact the DUTs.

The space transformer 112 is held in place by a holder 126. Screws 128 can adjust a relative position of the space transformer 112 with respect to the PCB 114. For example, the screws 128 can improve parallelism between the space transformer 112 and the PCB 114 to improve the contacts between the probe pins 116 and the dies under test 145.

In many applications, a reliable contact between the probe card 110 and the dies of the wafer 140 requires a relatively high contact force between the wafer and the probe card. In turn, this contact force may bend the probe card 110. Typically, the conventional space transformer 112 is less prone to bending than the PCB 114, because the space transformer is smaller than the PCB, and is also made of a stiffer material (e.g., ceramic) than the material of the PCB 114 (e.g., woven fiberglass cloth with an epoxy resin binder). Therefore, conventional probe cards include stiff eners 122a/122b and screws 124 to limit the bending of the PCB 114.

In general, an increasing number of die contacts distributed over a decreasing area of the die results in smaller contacts that are spaced apart by smaller distances (e.g., a smaller pitch). Furthermore, the characteristic diameter of the contact pins of the test contactor generally scales with a characteristic dimension of the contact structures on the semiconductor die. Therefore, as the contact structures on the die become smaller and/or have a smaller pitch, the contact pins of the test contactors become smaller, too. However, it is difficult to significantly reduce the diameter and pitch of the contact pins of the test contactor, for example, because of the difficulties in machining and assembling such small parts, resulting in low yield and inconsistent performance from one test contactor to another.

Figure 2A is an exploded view of a portion of a test stack 250 for testing semiconductor wafers in accordance with prior art technology. The test stack 250 routes signals and power from a tester (not shown) to a wafer 140 or other substrate carrying one or more devices under test (DUTs) 145, and then transfers the output signals from the DUTs (e.g., semiconductor dies) back to the tester for analysis and determination about an individual DUT's performance (e.g., whether the DUT is suitable for packaging and shipment to the customer).

The signals and power from the tester are routed through cables 239 to a tester translator interface board (TTI board) 230 to a wafer translator 210, and further to the semiconductor dies on the wafer 140. Conductive traces 238 carried by a test contactor substrate 232 can electrically connect the cables 239 to contacts 236 on the opposite side of the TTI substrate 232. In some embodiments, the TTI substrate 232 may be a printed circuit board (PCB). In operation, the TTI board 230 can contact an inquiry-side 213 of a wafer translator 210 as indicated by arrows A. In at least some embodiments, relatively large inquiry-side contact structures 214 can improve alignment with the corresponding contacts 236 of the TTI board 230. The contact structures 214 at the inquiry-side 213 are electrically connected with relatively small wafer-side contact structures 216 on a wafer- side 215 of the translator 210 through conductive traces 218 of a wafer translator substrate 212. The size and/or pitch of the wafer-side contact structures 216 are suitable for contacting the corresponding die contacts 148 of the wafer 220. The die contacts 148 may be relatively flat surfaces on the die, solder balls, copper balls, or other contact structures carried by the die. Arrows B indicate a movement of the wafer translator 210 to make contact with the die contacts 148 on an active side 125 of the wafer 140. As explained above, the signals and power from the tester can exercise the DUTs of the wafer 140, and the output signals from the tested DUTs can be routed back to the tester for analysis and a determination as to whether the DUTs operate per the specifications.

A wafer chuck 240 supports the wafer 140. Arrows C indicate the direction of the wafer 140 mating with the wafer chuck 240. In operation, the wafer 140 can be held against the wafer chuck 240 using, e.g., vacuum or mechanical clamping. In some cases, the contact structures 216 on the wafer-side of the wafer translator 210 may simultaneously contact all or almost all dies 145a, 145b, etc. on the wafer 140. In some cases, the diameter of the wafer translator 210 may generally correspond to the diameter of the wafer 140, or the wafer translator may have larger diameter than the corresponding wafer under test.

Figures 2B and 2C are partially schematic, top and bottom views, respectively, of a wafer translator configured in accordance with embodiments of the presently disclosed technology. Figure 2B illustrates the inquiry-side 213 of the wafer translator 210. Distances between the adjacent inquiry-side contact structures 214 (e.g., pitch) are denoted Pi in the horizontal direction and P ₂ in the vertical direction. The illustrated inquiry-side contact structures 214 have a width Di and a height D ₂ . The pitch, width and height of the contact structures 214 may be collectively termed "the characteristic dimensions." In different embodiments, the inquiry-side contact structures 214 may be squares, rectangles, circles or other shapes. Furthermore, the inquiry-side contact structures 214 can have a uniform pitch (e.g., Pi and P ₂ being equal across the wafer translator 10) or a non-uniform pitch.

Figure 2C illustrates the wafer-side 215 of the wafer translator 210. In some embodiments, the pitch between the adjacent wafer-side contact structures 216 can be pi in the horizontal direction and p ₂ in the vertical direction. The width and height of the wafer-side contact structures 216 ("characteristic dimensions") are denoted as di and d ₂ . In some embodiments, the wafer-side contact structures 216 can be pins that touch corresponding die contacts on the wafer 140. Lines 219 correspond to wafer streets that separate individual dies of the wafer 140 from each other. In general, the size/pitch of the inquiry-side contact structures 214 is larger than the size/pitch of the wafer-side contact structures 216. As a result, the alignment and contact is improved between the test contactor and the wafer translator.

However, it may be difficult to maintain a consistent contact between the die contacts 148 and the wafer-side contact structures 216 when contacting dies over a relatively large wafer 140 (e.g., over a wafer having 150 mm, 200 mm, or 300 mm diameter). Analogously, it may be difficult to maintain consistent contact between the contacts 236 on the TTI board 230 and the corresponding inquiry-side contact structures 214. For example, tilting or undulation (waviness) of the wafer translator may compress some contact pairings 214/236 and/or 216/148 too much, while some other contact structures do not have enough contact force or do not make contact at all. Generally, as the wafers 140 become larger, and the die contacts 148 become smaller, the consistency and reliability of the contact degrades. Accordingly, there remains a need for cost effective test contactors that can provide consistent contact with all devices under test (DUTs) on the wafer.

DESCRIPTION OF THE DRAWINGS

The aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on clearly illustrating the principles of the present disclosure. Figure 1A is a side cross-sectional view of a portion of a test stack for testing semiconductor wafers in accordance with prior art technology.

Figure IB is a bottom view of a portion of a test stack for testing semiconductor wafers in accordance with prior art technology.

Figure 2A is an exploded view of a portion of a test stack for testing semiconductor wafers in accordance with prior art technology.

Figure 2B is a partially schematic, top view of a wafer translator in accordance with prior art technology.

Figure 2C is a partially schematic, bottom view of a wafer translator in accordance with prior art technology.

Figure 3 is a bottom isometric view of a probe card assembly configured in accordance with embodiments of the presently disclosed technology.

Figure 4 is a top isometric view of a probe card assembly configured in accordance with embodiments of the presently disclosed technology.

Figure 5 is a side cross-sectional view of a probe card assembly shown in Figure

4.

Figure 6 is a detail view of a probe card assembly shown in Figure 5.

Figure 7 is a detail view of an individual probe card (DUT-let) shown in Figure 6.

Figures 8 and 9 are partial isometric views of individual probe cards in accordance with embodiments of the presently disclosed technology.

Figure 10 is an isometric view of an interposer in accordance with embodiments of the presently disclosed technology.

Figures 11 - 15 are partially schematic cross-sectional views of individual probe cards in accordance with embodiments of the presently disclosed technology.

Figure 16 is a bottom isometric view of an individual probe card configured in accordance with embodiments of the presently disclosed technology.

Figure 17 is a top isometric view of an individual probe card configured in accordance with embodiments of the presently disclosed technology.

Figure 18 is a partially exploded view of an individual probe card configured in accordance with embodiments of the presently disclosed technology.

Figure 19 is a top isometric view of an individual probe card configured in accordance with embodiments of the presently disclosed technology. Figure 20 is a bottom isometric view of an individual probe card configured in accordance with embodiments of the presently disclosed technology.

Figure 21 is an exploded isometric view of an individual probe card in accordance with embodiments of the presently disclosed technology.

Figure 22 is a bottom plan view of an individual probe card in accordance with embodiments of the presently disclosed technology.

Figures 23-25 are cross-sectional views of the individual probe card shown in Figure 22.

DETAILED DESCRIPTION

Specific details of several embodiments of representative probe card assemblies and associated methods are described below. A person skilled in the relevant art will also understand that the inventive technology may have additional embodiments, and that the technology may be practiced without several of the details of the embodiments described below with reference to Figures 3-25.

The inventive technology relates generally to equipment for semiconductor wafer test. More particularly, the present technology relates to methods and systems for contacting ("probing") the dies of the semiconductor wafer using probe card assemblies. In some embodiments, a probe card assembly includes multiple individual probe cards for contacting dies under test (DUTs) on the semiconductor wafer. An individual probe cards (also referred to as the "DUT-let") may be contacting one or more dies of the silicon wafer.

In some embodiments, the DUT-lets have die-level and pin-level compliance. For example, the individual DUT-let (i.e., the DUT-let contactor) may be individually pivotable to provide compliance and/or better contact with the individual dies on the wafer. In general, individual pivoting of the individual probe cards DUT-lets may improve the X-Y and vertical alignment against the corresponding dies of the wafer. Furthermore, a lateral motion (also referred to as a "scrub") between the pins of the DUT- let and the contacts of the individual dies may improve electrical contact between the pins of the DUT-let and the contacts of the dies. In some embodiments, the pivot of the DUT- let contactor may be asymmetric for improved scrub. In some embodiments, the vertical position of the DUT-lets (i.e., Z-position or distance of the DUT-let from the silicon wafer) may also be adjustable. Generally, the pins of an individual DUT-let have some vertical and some lateral pin-level compliance.

In some embodiments, the DUT-lets may carry electrical components (e.g., capacitors, resistors, active circuits, etc.) for signal/power conditioning. Furthermore, the electrical components that are placed close to the DUT may execute some functions that are normally performed by the tester. For example, the test vectors may be stored on the memory chips carried by the DUT-let, and these vectors may execute tests with relatively small return-trip-delay because of the short signal path between the DUT and the electrical components in comparison to the long signal path between the DUT and the tester. Signals from the individual DUT-lets may be routed through their corresponding individual contactors (e.g., flexible printed circuit board (PCB)) to the common PCB of the probe card assembly, and further to the tester.

Figure 3 is a bottom isometric view of a probe card assembly 3000 configured in accordance with embodiments of the presently disclosed technology. The illustrated probe card assembly 3000 includes multiple individual probe cards (DUT-lets) 700 facing the dies on the semiconductor wafer (not shown). A wafer-side support plate 600 provides mechanical support for the individual DUT-lets 700. A PCB 500 provides routing path for signals/power between the dies (DUTs) of the wafer the tester. In operation, an individual DUT-let 700 may be contacting ("probing") one or several dies of the silicon wafer.

Figure 4 is a top isometric view of the probe card assembly 3000 configured in accordance with embodiments of the presently disclosed technology. An outer stiffener 300 (sometimes referred to as a "spider" in the industry) can provide structural support for the elements of the probe card assembly 3000. In some embodiments, the outer stiffener 300 may be made of stainless steel or invar. The elements of the probe card assembly 3000 may be kept together, at least in part, by fasteners 310.

Figure 5 is a side cross-sectional view of the probe card assembly 3000 in accordance with embodiments of the presently disclosed technology. Typically, before the test commences, the outer stiffener 300 is attached to a prober (e.g., to a headplate of the prober). In operation, the prober chuck brings the semiconductor wafer 140 into the contact with the individual DUT-lets 700 of the probe card assembly 3000 to establish electrical path between the tester and the dies of the semiconductor wafer 140. In some embodiments, each DUT-let 700 faces one die 145 of the semiconductor wafer 140. In other embodiments, one DUT-let 700 can test two dies 145 in parallel, three dies 145 in parallel, etc. In some embodiments, the DUT-lets 700 may be distributed over the probe card assembly 3000 such that, for example, the DUT-lets 700 touch every other die 145 of the semiconductor wafer 140. As a result, the entire semiconductor wafer 145 is tested in two steps (also referred as "touch downs") by stepping the probe card assembly 3000 by one die between the touch downs. Analogously, the probe card assembly 3000 having the DUT-lets 700 that touch every third die 145 of the semiconductor wafer 140 takes three steps to test the entire semiconductor wafer. Other combinations of the DUT-lets 700 facing the dies 145 of the semiconductor wafer 145 are also possible.

In the illustrated embodiment, the wafer-side support plate 600 structurally supports the DUT-lets 700. In some embodiments, the wafer-side support plate 600 may be made of invar, stainless steel, ceramic or other material. In some embodiments, the invar (nickel -iron) alloy may have low coefficient of thermal expansion (CTE) or a CTE that is comparable to that of the silicon wafer itself. As a result, the thermal mismatch between the probe card assembly 3000 and the silicon wafer 140 is reduced.

The PCB 500 provides routing path for signals and power between the dies under test (DUTs) 145 of the semiconductor wafer 140 and the tester. The PCB 500 may be structurally supported by a backing plate 400 and further by the outer stiffener 300. In some embodiments, the backing plate 400 is made of metal or ceramic. The backing plate 400 may have opening to route the cables or other conductors from between the DUT-lets 700 and the tester.

Figure 6 is a detail view of the probe card assembly 3000 shown in Figure 5. The illustrated probe card assembly 3000 includes the DUT-let 700, the wafer-side support plate 600, the tester-side PCB 500, the backing plate 400, and the outer stiffener 300. The DUT-let 700 faces the die under test 145 of the semiconductor wafer 140. In operation, contact structures 712 contact the contact pads (or other contact structures) of the die under test 145. In some embodiments, all dies 145 of the semiconductor wafer 140 may be contacted simultaneously by their corresponding DUT-lets 700. In other embodiments, a subset of the dies 145 of the semiconductor wafer 140 is contacted simultaneously by their corresponding DUT-lets 700. In different embodiments, the contact structures 712 can be pins, micro-electro-mechanical-systems (MEMS), or other electrical contact structures. Details of the DUT-let 700 are shown in Figure 7.

Figure 7 is a detail view of the DUT-let 700 shown in Figure 6. In some embodiments, the DUT-let 700 includes a routing substrate 710 that carries the contact structures 712. The routing substrate 710 may be a substrate having electrical traces, for example, a PCB (e.g., a relatively thin flexible PCB also referred to as a "flex"), a ceramic substrate, a glass substrate, a silicon substrate, or other planarizable and polishable material having electrical traces.

In some embodiments, the routing substrate 710 carries the contact structures 712 for contacting the DUTs. The routing substrate 710 may carry electrical components 714 (e.g., capacitors, resistors, memory, active circuits, etc.) for signal/power conditioning. In some applications, testability of the DUT is improved when the electrical components 714 are placed relatively close to the die under test (DUT).

In some embodiments, a DUT-let stiffener 730 structurally supports the routing substrate 710. An adhesive component 720 may attach the DUT-let stiffener 730 to the routing substrate 710. The DUT-let stiffener 730, the adhesive component 720, the contact structures 712, and the portion of the routing substrate 710 that carries the contact structures 712 is collectively termed a DUT-let contactor 709. In some embodiments, a gimbal 740 and a dome 750 support the DUT-let against the wafer-side support plate 600. An adhesive (not shown) may connect the gimbal 740 and the DUT-let stiffener 730. In some embodiments, a controllable microfluidic element may be used in place or in conjunction with the gimbal 740 and the dome 750.

In some embodiments, the routing substrate 710 provides electrical path between the dies under test and an interposer 770 located between the routing substrate 710 and the tester-side PCB 500. The routing substrate 710 may pass through an opening 610 in the wafer-side support plate 600. In some embodiments, the interposer 770 includes interposer pins 772 that contact corresponding contact pads 716 of the substrate 710. The opposite side of the interposer 770 may include similar pins to route power/signals from interposer pads 774 to electrical traces 510 of the tester-side PCB 500, and further to/from the tester. An upper stiffener 760 may structurally support the routing substrate 710 against the wafer-side support plate 600.

Figure 8 is a partial isometric view of the individual DUT-lets in accordance with embodiments of the presently disclosed technology. The illustrated individual DUT- lets 700-1, 700-2 each carry an array of the contact structures 712, but other layouts of the contact structures 712 are possible, depending on the layouts of the contacts on the die under test (DUT). In operation, the DUT-lets 700-1, 700-2 contact one or more dies under test 145 to establish electrical path between the tester and the dies under test (DUTs). The DUT-lets 700-1, 700-2 are structurally separated, and, therefore, their respective DUT-let contactors 709 have independent die-level compliance. For example, the DUT-lets 700-1 and 700-2 may be at different heights (i.e., different distances from the silicon wafer) and/or not be parallel before contacting their corresponding dies under the test. For instance, the DUT-let 700-1 may contact the corresponding die 145 before the DUT-let 700-2 contacts its corresponding die 145. However, because DUT-lets 700- 1, 700-2 are structurally separated, both DUT-lets 700-1, 700-2 (and other DUT-lets of the assembly) may make contact with their respective dies under test even when the DUT-lets are mutually out of plane within the probe card assembly 3000. As a result, the tolerances for the DUT-let contact height planarity within the probe card assembly 3000 may be relaxed, and the contact between the DUT-lets 700 and the dies under test 145 may be improved. The contact structures 712 of an individual DUT-let also have some vertical and some lateral pin-level compliance that further improves contact between the DUT-lets 700 and the dies under test 145. The DUT-lets 700-1, 700-2 are supported by the wafer-side support plate 600.

Figure 9 is a partial isometric view of the individual DUT-lets in accordance with embodiments of the presently disclosed technology. The wafer-side support plate 600 is not shown for better visibility of other components. In some embodiments, a retainer clip 776 keeps the interposer 770 in place and aligns the interposer against the contact pads 716 of the substrate 710. In some embodiments, the tester-side PCB 500 makes electrical contact with the interposer 770.

Figure 10 is an isometric view of the interposer 770 in accordance with embodiments of the presently disclosed technology. In some embodiments, the interposer 770 is an electrical contactor having spring-like or spring-loaded interposer pins 774. The substrate of the interposer 770 may be PCB, ceramic, or other material. When the probe card assembly 3000 is assembled, the interposer pins 774 make electrical contact with the corresponding contact pads 716 of the tester-side PCB 500.

Figures 11 - 15 are partially schematic cross-sectional views of individual probe cards in accordance with embodiments of the presently disclosed technology. For simplicity and clarity, Figures 11 - 15 show one DUT-let 700 contacting the die under test (DUT) 145, however, in operation, the probe card assembly 3000 includes multiple DUT-lets contacting their corresponding dies under test or groups of dies under test 145.

Figure 11 shows the DUT-let 700 in contact with the die under test 145. In operation, the gimbal 740 and the dome 750 can improve alignment of the DUT-let 700 against the die under test 145. For example, the combination of the gimbal 740 and the dome 750 can provide a pivoting motion of the contact structures 712, thus compensating for some difference in planarity between the DUT-let contacts 712 and the corresponding dies under test 145. In some embodiments, a shear modulus of the gimbal 740 can limit the lateral motion of the DUT-let 700 such that the contact structures 712 do not travel beyond the corresponding contact structures of the dies 145. Furthermore, flexibility and deformability of the dome 750 may compensate for some inaccuracies in the vertical distance between the individual DUT-lets 700 and the wafer 140. In some embodiments, the gimbal 740 and the dome 750 are connected by, for example, welding, brazing, soldering, or by an adhesive element 745.

Figure 12 shows the DUT-let 700 in contact with the die under test 145. In some embodiments, the dome 750 can be a snap-dome with an opening in the dome 750 for snapping-in the gimbal 740. In some embodiments, the dome/gimbal combination may be a ball and socket subassembly of a ballpoint pen, which typically has relatively high accuracy of the ball and the socket (e.g., micrometer level accuracy) at a relatively low cost (e.g., a fraction of a dollar) and a relatively low force applied to the ball and socket subassembly.

In operation, the gimbal 740 may bend laterally (e.g., in response to an off-center loading), therefore improving the lateral scrub against the contact structures of the die under test 145. In some embodiments, the DUT-let 700 includes a DUT-let substrate 725 having through-vias 726 for electrically connecting the contact structures 712 with the routing substrate 710. The routing substrate 725 may be a PCB or a ceramic substrate.

Figure 13 shows the DUT-let 700 in contact with the die under test 145. In some embodiments, the DUT-let 700 includes multiple gimbals 740-1, 740-2. In some embodiments, the gimbals 740-1, 740-2 have different cross-sections, different material properties, and/or are distributed asymmetrically. As a result, the DUT-let contactor 709 may have a preferred direction of pivot, therefore, at least in some cases, improving the alignment between the contact structures 712 and the corresponding contact structures of the DUTs on the wafer. In some embodiments, the asymmetric gimbals 740-1, 740-2 improve lateral scrub of the contact structures 712.

Figure 14 shows the DUT-let 700 in contact with the die under test 145. The illustrated DUT-let 700 includes the gimbal 740 connecting the DUT-let substrate 725 and the wafer-side support plate 600. In some embodiments, the gimbal 740 may be shaped to promote its bending by, for example, making the middle part of the gimbal 740 more narrow than are its upper and lower ends. As a result, the pivoting of the contact structures 712 may be improved when the contact structures 712 contact the die under test 145.

Figure 15 shows the DUT-let 700 in contact with the die under test 145. The illustrated DUT-let includes wirebonds 711 for electrically connecting the DUT-let substrate 725 and the routing substrate 710. In some embodiments, the wirebonds may be attached to the through-vias 726 (or the pads attached to the through-vias 726) of the DUT-let substrate 725.

Figures 16 and 17 are bottom and top isometric views, respectively, of the DUT- let 700 configured in accordance with embodiments of the presently disclosed technology. The DUT-let 700 is supported by the wafer-side support plate 600. In operation, multiple DUT-lets 700 may be included in the probe card assembly 3000.

Figure 18 is a partially exploded view of the DUT-let 700 configured in accordance with embodiments of the presently disclosed technology. In operation, the contact structures 712 of the DUT-let 700 protrude through an opening 615 to make electrical contact with the dies under test 145 of the silicon wafer 140, therefore providing electrical path between the die under test 145 and the tester. A clamp 780 may structurally support the routing substrate 710 against the wafer-side support plate 600. In some embodiments, fasteners 762 keep the clamp 780 engaged with the wafer-side support plate 600 and the DUT-let 700.

Figures 19 and 20 are top and bottom isometric views, respectively, of the DUT- let 700 configured in accordance with embodiments of the presently disclosed technology. For better clarity of these views, the wafer-side support plate 600 and the clamp 780 are not shown.

Figure 21 is an exploded isometric view of the DUT-let 700 in accordance with embodiments of the presently disclosed technology. In operation, the routing substrate 710 is electrically connected with the tester-side PCB 500, and further with the tester. Starting from the bottom of the view, the contact structures 712 face individual DUTs of the silicon wafer (not shown). The contact structures 712 are supported by the routing substrate 710. In some embodiments, the routing substrate 710 may be a flexible PCB. In the probe card assembly 3000, the routing substrate 710 is electrically connected with the tester-side PCB 500 and further with the tester 150.

In the illustrated embodiment, the DUT-let stiffener 730 structurally supports the back side of the routing substrate 710. The adhesive component 720 may attach the DUT-let stiffener 730 to the routing substrate 710. The adhesive component 720 can be an elastomer providing a small amount of overall compliance or mitigation of non- planarity.

In some embodiments, the DUT-let 700 includes multiple pivoting structures, for example, a first pivoting structure having the dome 750 and a dome weldment 752, and a second pivoting structure having an upper dome 754 and an upper dome housing 756. With the first pivoting structure 750/752, the DUT-let contactor 709 can pivot at the surface of the dome 750. With the second pivoting structure 754/756, the upper dome 754 can pivot in a depression 757 of the upper dome housing 756. The upper dome 754 can be attached to a flex mount 748, therefore allowing the flex mount 748 to pivot too. In some embodiments, the presence of the two pivoting structures 750/752 and 754/756 facilitates better alignment and/or contact of the DUT-let 700 with the contacts of the die under test. In some embodiments, one corner of the dome 750 can be point-welded onto the dome weldment 752. In operation, when the stiffener 730 compresses the pivoting structure 750/752, the dome 750 may move sideways (away from the point weld at the dome weldment 752) to provide lateral scrub of the contact structures 712 over the corresponding structures of the die under test.

Figure 22 is a bottom plan view of the DUT-let 700 in accordance with embodiments of the presently disclosed technology. The cross-sectional views 23 - 25 are discussed with reference to Figures 23 - 25 below.

Figure 23 is a cross-sectional view 23 - 23 of the DUT-let 700 shown in Figure 22. In some embodiments, the contact between the contact structures 712 and the corresponding contact structures of the die under test is improved by the first pivoting structure that includes the dome 750 and the dome weldement 752, and the second pivoting structure that includes the upper dome 754 and the upper dome housing 756. Figure 24 is a cross-sectional view 24 - 24 of the DUT-let 700 shown in Figure 22. In some embodiments, the DUT-let 700 includes positioning screws 744 that have pins 743 with adjustable height. In operation, the positioning screws 744 can be adjusted such that the pins 743 extend-toward and make contact- with the DUT-let stiffener 730. In some embodiments, by extending the pins 743 and contacting the DUT-let stiffener 730, the plane of the DUT-let stiffener 730 and, consequently, the plane of the contact structures 712 can be adjusted. As a result, the contact structures 712 may better align against the corresponding contact structures of the die under test.

Figure 25 is a cross-sectional view 25 - 25 of the DUT-let 700 shown in Figure 22. In some embodiments, the DUT-let 700 includes leveling screws 742 that can adjust the plane of the flex mount 748. For example, the DUT-let 700 may include three leveling screws 742 to define the leveling plane of the flex mount 748, which, in turn, defines the leveling plane of the contact structures 712.

In some embodiments, the DUT-let 700 includes adjustment screws 746 that can adjust an angle of the plane of the flex mount 748. In some embodiments, the adjustment screws 746 can also adjust a distance of the flex mount 748 from the upper stiffener 760, therefore adjusting a vertical distance of the contact structures 712 from the corresponding contact structures of the die under test. As a result, the contact structures 712 may achieve better alignment and/or more precise distance with respect to the corresponding contact structures of the die under test.

Many embodiments of the technology described above may take the form of computer- or controller-executable instructions, including routines executed by a programmable computer or controller. Those skilled in the art will appreciate that the technology can be practiced on computer/controller systems other than those shown and described below. The technology can be embodied in a special-purpose computer, controller, or data processor that is specifically programmed, configured, or constructed to perform one or more of the computer-executable instructions described below. Accordingly, the terms "computer" and "controller" as generally used herein refer to any data processor and can include Internet appliances and hand-held devices (including palm-top computers, wearable computers, cellular or mobile phones, multi-processor systems, processor-based or programmable consumer electronics, network computers, mini computers and the like). Information handled by these computers can be presented by any suitable display medium, including a CRT display or LCD.

From the foregoing, it will be appreciated that specific embodiments of the technology have been described herein for purposes of illustration, but that various modifications may be made without deviating from the disclosure. Moreover, while various advantages and features associated with certain embodiments have been described above in the context of those embodiments, other embodiments may also exhibit such advantages and/or features, and not all embodiments need necessarily exhibit such advantages and/or features to fall within the scope of the technology. Accordingly, the disclosure can encompass other embodiments not expressly shown or described herein.