Probe head having a membrane suspended probe

This patent application is a US provisional patent application No. 60 / 586,299 filed on July 7, 2004 for a "probe head with a membrane suspension probe" invented by Keneth Smith, Michael Jolley and Victoria Van Sycle. Claims the interests of.

The present invention relates to a type of probe assembly commonly used for inspection of integrated circuits (ICs), in particular a probe assembly that provides a finely pitched, compliant, very low inductance probe.

Integrated circuit technology makes it possible to process a large number of individual electronic circuit elements on a single substrate, or "wafer." After processing, the wafer is divided into a large number of rectangular chips, i.e. dies, and the electronic circuits on each of the divided dies have a rectangular or other regular arrangement that can be input / output connected to it. It is equipped with a metal-coated contact pad or coupling pad having a metal coating. The individual dies are eventually packaged separately, but for efficiency, the circuits formed on each die are inspected while the dies are still engaged on the wafer. Is preferable. In an example of a typical process, the probe assembly is supported by supporting the wafer on a flat stage, i.e., moving the wafer in the X, Y and Z axes with respect to the head of the probe assembly in a "chucked" state. The tip of the probe protruding from the die can be moved from one die to another and continuously engaged with the contact pads of each die. Further, when the corresponding signal, power, and grounding conductor are connected to the probe tip, each circuit is continuously connected to check whether the device can be operated by the inspection device.

The first type of probe assembly used to inspect an integrated circuit uses a large number of needle-like contacts arranged in a pattern that matches the pattern of the contact pad on the device under inspection. 1 and 2 show a probe assembly 20 including a needle card probe head 22 with an array of needle-like probes 24 constrained by an upper needle card 26 and a lower needle card 28. These upper needle card 26 and lower needle card 28 are provided with patterned holes corresponding to the contact pad arrangement of the IC or other device inspected by the probe assembly 20. The lower end of each probe 24 extends through one hole in the lower needle card 28 and terminates as a pointed probe tip. The upper end of each probe 24 is constrained by a hole in the upper needle card 26. Note that the hole in the upper needle card 26 is covered by a conductive pad 32 located on the surface of the space transformer 30 (shown as a bracket), so that it can be used with the pressing pad on the device to be inspected. When the lower end of the probe is pressed and engaged, the upper end of the probe is prevented from sliding through the needle card on the upper side. This space transformer is a rigid multilayer plate having electrically conductive contact portions 32 and 36 on facing surfaces electrically connected by a conductive trace 34 extending in the plate. The space transformer 30 also transmits electrical signals from the fine pitch pattern of the needle probe 24 to the coarser pitch pattern obtained on the probe card 38 by the printed circuit board to which the inspection device is connected to the probe assembly.

A typical probe assembly 20 includes an interposer 39 that is located between the space transformer 30 and the probe card 38. The interposer 39 generally includes a large number of elastic variable contacts that are electrically connected via the circuit board in order to make electrical connections corresponding to both sides of the circuit board. In addition, the compliance of the conductor compensates for changes in the distance between the terminals of the space transformer 30 and the terminals of the probe card 38, facilitating reliable electrical connections between them.

Generally, the needle probe 24 includes a wire that includes a complementary bend that forms a substantially parallel top and bottom with the top edge of the probe offset and the bottom edge in the vicinity. The offset of the hole pattern of the lower needle card 28 and the hole pattern of the upper needle card 26 corresponds to the offset of the probe end. When the lower end of the probe is pressed to engage the contact pad on the die, the substantially cylindrical probe bends at the offset portion to act as a spring. The compliance due to the elastic bending of the probe can cope with changes in the probe length, the flatness of the probe head, and the wafer microstructure.

Needle card probe assemblies have been commonly used in wafer inspection, but electronic products, especially IC products, have become more complex circuits with higher frequencies, smaller circuit elements and geometry. It has become clear that this type of probe assembly imposes various limitations on the current trend. First, the pitch width, which is the distance between the probes, is limited to about 125 μm, which is far from the preferred spacing for many ICs with finely pitched contact pads due to manufacturing tolerance and assemblability requirements. Has been done. In addition, since the metal contact pad of the die oxidizes rapidly, the tip of the probe can be sharpened to obtain the high conductivity required for accurate measurement when pressed against the surface of the contact pad. However, this can lead to rapid blunting of the sharpened probe end, frequent bending or crushing of the probe, and damage to the contact pad when the degree of erosion is high. Also, in many cases, the contact pad material adheres to the probe, which often requires cleaning with damage to the probe. The inductance of a parallel conductor is a function of the conductor length and the distance between the conductors. In general, relatively long, narrowly spaced needle probes have a single pass inductance of 1-2 nH, which significantly distorts high frequency signals and limits the practicality of needle probes for inspecting high frequency devices.

The second type of probe assembly invented by Gleason et al., Described in Patent Document 1 (US Pat. No. 6,708,386B2), is incorporated herein by reference. As shown in FIG. 3, the membrane probe assembly 40 is provided with a probe card 52 and a membrane probe assembly 42 to which data from the device and signal lines 48 and 50 are wired. As shown in FIGS. 3 and 4, the membrane probe assembly 42 comprises a support element 54 formed of an uncompressed material such as a hard polymer. The element is threaded through the bolt 56 (each bolt is threaded through the corresponding support element mounting arm 60, and the individual backing elements 62 evenly distribute the bolt tightening pressure of the support element over the entire back surface. ) And the corresponding nut 58 are detachably connected to the upper part of the probe card. Devices with different contact pad arrangements can be quickly replaced as needed with different probe assemblies with different contact arrangements for probe inspection.

As shown in FIGS. 4 and 5, the support element 54 includes a rear base portion 64 that is integrally coupled with the mounting arm 60. The support element 54 also includes a plunger 66 that projects outward from the front support, i.e., the flat base. This front support portion has a side portion 68 inclined so as to focus on the flat support portion surface 70, and has a pyramidal trapezoidal shape. As shown in FIG. 4, the flexible film assembly 72 is aligned with the alignment pins 74 provided on the base and then attached to the support. The flexible film assembly is composed of one or more layers of insulating polyimide film, with flexible conductive layers or strips disposed between layers or layers to form the data / signal lines 76.

As shown in FIG. 5, when the support element 54 is installed on the upper side of the probe card 52, the front support 66 protrudes through the central opening 78 in the probe card, thereby above the central region 80 of the elastic membrane assembly. The contact portion arranged in the above is preferably arranged and press-engages with the contact pad of the die to be inspected or other device to be inspected. As shown in FIG. 4, the membrane assembly comprises a radially extending arm segment 82 separated by an inwardly curved edge 84, which is shaped like a foamy cloth, and these segments are By sloping and extending along the sloping side 68, any parts that project while surrounding the pad are cleared. Since the terminal of the data / signal line 76 is provided with a series of contact pads 86, when the support elements are installed, these pads are electrically connected to the corresponding termination pads provided on the upper side of the probe card. By engaging, the data / signal line 48 on the probe card is electrically connected to the contact on the central region.

The probe assembly 42 provides a highly reliable general contact pad-to-pad in a densely-arranged contact pad, whether the contact pad has an oxidized surface over a number of contact cycles. Probing can be done with a flexible electrical connection. To that end, membrane assemblies are constructed and support elements such that when these pads are pressed engaged, the contacts on the membrane assembly are wiped or polished laterally across the contact pads by local control means. Connect to.

FIG. 8 is an enlarged view of a specific example of the central region 80a in the membrane assembly 72a, and is a contact portion arranged in a quadrangular pattern suitable for engagement with a contact pad on a die arranged in the quadrangular pattern. It shows 88. The membrane assembly is provided with a space transformer that terminates the data / signal lines 76 from the densely arranged ultrafine pitch contact 88 to the coarser pitch contact 86.

Further, as shown in FIG. 9A, which is a cross-sectional view taken along the line 9A-9A of FIG. 8, an extremely thick rigid beam 90 is provided at each contact portion formed by the rigid contact bump 92 at one end thereof. The contact bump has a contact portion 93 on it, and a rhodium knob is attached to the contact bump. By electroplating, each beam forms an overlapping connection with the end of the repellent conductive trace 76a to form their joint. The conductive trace connected to the back conductive layer 94 effectively provides data or signal lines with controlled impedance at the contacts. This is because the dimensions are set using photolithography.

A sandwiched elastomer layer 98 that spreads on the same surface as the support surface and can be formed with a silicone rubber compound connects the membrane assembly to the flat support surface 70. The flat support surface described above is preferably made from an incompressible material such as a hard dielectric such as polysulfone or glass. As shown in FIG. 10, when one of the contact portions 88 press-engages with the contact pad 100 of the corresponding die, the resulting decentering force from the rigid beam 90 and the bump 90 structure are the elastomeric pad 98. pressurized so against the elastic restoring force of the et, so that the beam is pivoted or inclined. This tilting motion is localized in that the anterior portion 102 of the beam travels a greater distance towards the flat support surface 70 than the posterior portion 104 of the beam. This has the effect of driving the contact portion to perform a lateral wiping operation over the entire contact pad, and the start position of contact on the pad is indicated by a dotted line and the contact end position is indicated by a solid line. This method polishes the buildup of insulating oxides on each contact pad, ensuring proper electrical connection between the contact and pad.

The contacts of the membrane probe assembly can be placed at a fine pitch that engages the contact pads on physically small devices by being wiped locally, providing wear and damage resistance and resistance. However, it will be possible to make contact with high conductivity. In addition, the membrane suspension probe can connect a large region with a short length and has a lower inductance than a general needle probe, so that it can be used in a high frequency region, and signals in all frequency bands can be used. The distortion can be reduced.

<patcit num="1"><text>U.S. Pat. No. 6,708,386B2</text></patcit>

<p> However, the probe and signal / data line are formed on the surface of the membrane and are connected to a probe card terminal provided around the periferi of the membrane. Previous probe cards and spatial converters could be used with needle card probe heads where the signal path passes through the center of the probe assembly and is located substantially parallel to the central axis of the probe assembly. It could not be used with a membrane suspension probe. For this reason, there is a need for devices and methods that allow finely pitched, rigid, low-inductance membrane suspension probes to be used with needle-type probe heads and components of probe assemblies used.</p>

As shown in detail in the figure with similar reference numerals for similar parts, specifically, the main functional components included in the embodiment of the probe assembly 20 used as the needle-type probe shown in FIG. Is a probe card 38, an interposer 39, a space transformer 30, and a probe head 22. Further, as shown in FIG. 2, the needle-shaped probe 24 in the probe head provides a means for temporarily connecting to a contact pad on a die contained in a semiconductor wafer or another device (DUT) to be inspected. It provides and inputs and outputs signals to the internal electrical circuit on the DUT. The needle-shaped probe inputs and outputs signals from the die from the probe head 22 through a pad on the conductive terminal 32 or the space transformer 30. The signal of the needle card probe assembly is generally collected near the center of the probe assembly and is normal to the device under inspection. Since needle probes are frequently used to probe ICs, they are subject to various restrictions, have finely pitched features, and are optimal for ICs and other devices used in the high frequency domain. It becomes impossible to perform probe processing under various conditions.

On the other hand, since the membrane probe has a considerably lower inductance than the needle type probe, the membrane probe can probe a high frequency circuit. Further, the tip of the membrane suspension probe is due to local contact through the insulating oxide layer formed on the IC contact pad without accumulating contact pad material on the probe tip as in a normal needle-type probe. It can be arranged so as to be wiped off. Previous membrane suspension probes have not been able to probe assemblies used with needle-type probes. This is because the membrane suspension probe and the conductive trace that connect the probe and the probe card are arranged on the surface of the elastic membrane, and the traces extend radially over the surface of the membrane, so that the vicinity of the periferi of the elastic membrane is formed. This is because it is connected to the probe card terminal arranged in. The inventors envision using a membrane suspension probe with a probe assembly when the membrane suspension probe can be conductively connected to a space transformer located opposite the membrane probe tip. It was concluded that it could be used with a needle-type probe. 11 and 12 show a probe assembly 100 comprising a needle probe type probe head and components that can be used, including a probe head 102 having a large number of elastic membrane suspension probes 104. This needle card probe assembly can be changed to a probe assembly with a membrane suspension probe by removing the needle card probe head and replacing it with a membrane probe facing a space transformer that can face the needle card probe head. Can be done. Further, in the schematic cross-sectional view shown in FIG. 12, the figure is clarified by exaggerating some elements and parts.

The probe 38 is a common prior art circuit board with a large number of terminals 120 on its surface (although only two of them are shown). This terminal provides an interface for wire 122 that connects the device (not shown) to the probe assembly. As shown, the wire 122 can be connected to the terminal 120 on one side of the probe card 38 and then connected to the terminal 126 or trace on the opposite side of the circuit board by a conductive bias 124. Further, additional components (not shown) such as active electronic components, passive electronic components, connectors and the like thereof can be mounted on the probe card 38 and connected to the additional terminal 120. Probe card 38 is generally circular and has a diameter on the order of about 30 cm (12 inches). The terminals 122, 126 on the circuit board are often arranged at 2.54 mm (100 mil) pitch intervals or separation distances.

Some probe assemblies do not use an interposer 39, but the probe assembly 100 includes an interposer 39 that is located between the probe card 38 and the space transformer 30. The interposer 39 includes an electrical contact portion arranged and connected on the opposite surface of the substrate so that the components on both sides of the substrate are conductively connected. Interposers are frequently used in probe assemblies to facilitate reliable conductive connections between probe card terminals and space transformer terminals. The interposer also helps to accommodate various thermal expansions in the probe card 38 and space transformer 30. The interposer 39 comprises a number of fuzz buttons 130 protruding into the holes in the substrate 128 and the substrate (only two are shown). Each fuzz button 130 has a fine wire that is compressed into a small cylinder shape and becomes a conductive elastic wire mass. In a general arrangement, the fuzz buttons 130 are arranged at a pitch that matches that of the terminal 126 of the probe card 38. One end of the conductive fuzz button 130 contacts the terminal of the probe card 138, and the other end of the fuzz button contacts the terminal 140 on the space transformer 30. The elastic fuzz button 130 is pressed to have compliance to adapt to the variety of distances between the various terminals of the probe card and space transformer, and exerts its pressure to increase conductivity at the contacts. ..

The fuzz button 130 extending within the substrate 128 of the interposer 39 contacts the conductive terminal 140 on one side of the space transformer 30. The space transformer 30 (shown as a bracket) is located on the surface near the interposer 39 (showing only two of them) on a large number of terminals (contact areas, pads) and on the opposite surface. It comprises a suitable circuit board 142, such as a multilayer ceramic substrate having a large number of terminals (contact areas, pads) arranged (showing only two of them). In a typical probe assembly 100, the contact pads 140 near the interbosa 39 are arranged at the pitch of the terminals of the probe card 38, and the contact pads 144 arranged on the opposite surface of the space transformer 30 are The space transformers are arranged at a fine pitch corresponding to the pitch and arrangement of the needle-type probes included in the needle card probe that is supposed to face each other. When the terminal pitch of the probe card 38 is about 2.54 mm (100 mil), the needle-type probe can have a fine pitch interval of up to about 125 μm. The conductive trace 146 in the multilayer board 142 of the space transformer 30 transmits electrical connections from a fine pitch pattern for facing the probe head to a coarser pitch pattern on a printed circuit board such as the probe card 38.

Since the various substrates of the probe assembly 100 are laminated, any suitable mechanism can be used to stack these components to ensure reliable electrical contact. As shown, the probe assembly 100 comprises a rigid back mounting plate 150 disposed on one side of the probe card 38 and a rigid front mounting plate 152 located on the opposite surface of the probe card. The bolt 154 constrains the front mounting plate 152 to the rear mounting plate 150. A rectangular standoff portion 156 with a central opening that receives the space transformer 30 is attached to the front mounting plate. The mounting ring 158, preferably made from a spring material such as copper phosphate and having a pattern of extending elastic tabs, has a bolt 160 with the space transformer 30 placed between the mounting ring and the standoffs. Can be attached to standoff 156.

The mounting ring 156 grabs and holds the probe head 102, which comprises a multilayer substrate 160 (shown as a bracket) and a number of conductive membrane suspension probes 104. The probe 104 generally comprises a fairly thick, fixed beam 160 in which the beam contact portion 166 is near one end of the beam and the probe tip 168 projects from the beam near the other end of the beam. Other shapes and materials may be available, but in general, the probe tip 168 has the shape of a pyramidal base, and when the protruding end of the probe tip is covered with a layer of nickel or rhodium, It provides high conductivity and abrasion resistance when repeatedly press-engaged with a contact pad on the device under inspection. The beam contact portion 166 has a mushroom-like cross section with a contact button having a circular edge that facilitates mobile contact with the terminal 144 of the space transformer 30, and is slightly smaller than the contact button to the beam contact button. It has a cylinder-shaped or prism-shaped base cross section to be connected. The beam contact portion 166 projects from the side surface of the beam 164 on the opposite side of the beam tip portion 168 toward the opposite direction. As shown in FIG. 12, since the beam contact portion at least protrudes from the upper surface of the multilayer substrate 160 or is in the same plane, it can be exposed on the upper surface of the substrate and make conductive contact with the corresponding terminal 144 of the space transformer 30. And. Unlike the needle probe, the membrane suspension probe is a local wipe, ie, the contact pad of the DUT, because the ratio of cross-sectional area to length is significantly higher in the membrane suspension probe 104 than in the typical needle probe 24. It does not require a sharpened tip to penetrate the oxide deposited on it. Membrane probe head 102 has a single pass inductance well below 0.5 nH, 0. It has a 2nH single-pass inductance. As a result, the membrane suspension probe can be used in a higher frequency band than that of a needle probe, which generally has an inductance of greater than 1nH and often increases up to 2nH, due to the significantly lower signal distortion.

US Pat. No. 6,708,386B2 of Gleason et al., Incorporated in this invention, discloses "bottom-up" and "top-down" methods for producing membrane probes. Both methods can be used in the manufacture of the membrane probe head 102. Membrane suspension probes 104 manufactured by these methods can be aligned and constructed at pitches smaller than 100 μm, and are therefore denser than needle probes, which are generally pitch-limited to 125 μm or higher due to manufacturing tolerances and assemblability. It is possible to use a membrane suspension probe for a test device with a contact pad located in. A portion of the beam contact 104 that connects to the terminal 144 is also coated with a nickel or rhodium layer to enhance conductivity and wear resistance.

The multilayer substrate 160 includes an elastic film 170 and a large number of flexible insulating layers 172 and 174. The elastic film 170 is arranged near or in contact with the surface of the space transformer 30. The elastic membrane 170 is made by Borden's ELMER'S STICK ALL J and Dow. It contains a silicone rubber component such as Corning's Sylgard 182, and can exert an elastic restoring force on the surface of the film when it is deformed. The multilayer substrate 160 of the probe head includes a flexible first insulating layer or member 172 and a flexible second insulating layer or member 174. The first insulating layer 172 is arranged between the bottom layer 176 of the elastic film 170 and the top layer of the beam 164 of the probe 104. The second insulating layer 174 extends downward from the bottom layer of the first insulating layer to a depth approximately equal to the thickness of the beam portion 164 of the probe 104. The first insulating layer 172 and the second insulating layer 174 are thin and have rigidity in the normal direction with respect to the surface, but in order to fix the side portion of the probe 104, the direction parallel to the surface is used. Has sufficient rigidity. The first insulating layer 172 and the second insulating layer 174 may contain polyimide, but can be any other dielectric material having suitable physical properties.

As shown in FIG. 13, the probe tip 168 is press-engaged with the corresponding contact pad 200 on the device 202 to be inspected so that the resulting contact force pushes the probe tip up towards position 168'. Work like. The upward displacement of the probe 104 is resisted by the contact force on the contact surface between the space transformer contact portion 144 and the beam contact portion 166. As a result, the probe 104 rotates toward position 104', and the end of the probe tip 168 is laterally displaced on the contact pad 200. This lateral displacement, or wiping (S), abrades the insulating oxide formed on the contact pad and ensures conductivity between the reliable probe tip 168 and the contact pad. Since the probe tip 168 is displaced upward, the movable first insulating layer 172 also moves upward when the beam 166 is pushed upward from the elastic membrane. Since the surface of the membrane is stretched and distorted, a force that restores the first insulating layer 172 and the probe 104 to the "rest" position acts from the elastic membrane. When the upper surface of the elastic film 170 comes into contact with the surface of the space transformer 30, the upward displacement of the probe 104 gives the first insulating layer 172 a further restoring force because the lower surface of the elastic film presses the film. The restoring force from the elastic membrane 170 on the flexible insulating layer 172 releases the contact force at the probe tip 168 and returns the probe tip 104 to its initial position when the DUT 202 is separated from the probe head 102.

In the second embodiment of the membrane suspension probe 215 with the probe head 250 shown in FIG. 14, it may be used with a space transformer 30 having a protruding contact portion 258 such as a solder sphere. The probe 251 comprises a beam 252 having a probe tip 254 protruding from one end of the beam. The beam contact portion 256 passes through the elastic film and the opening 266 passing through the first insulating layer 262 and is exposed from the upper surface of the elastic film 260. The protruding space transformer contact portion 258 contacts the beam 252 at the exposed beam contact portion near the beam end on the opposite side of the probe tip portion 254. When the contact pad 200 of the DUT 202 is pressed into contact with the probe tip 254, the probe 251 rotates around the beam contact 256, producing a wiping action that removes the oxides deposited on the contact pad.

As shown in FIGS. 15 and 16, in another embodiment of the probe head with the membrane suspension probe 300, one or more membrane suspension probes 104 can be mounted on the surface of the space transformer 30 on tile 302. Included in. The tile 302 is from one or more probes 104 having a beam portion 164, an elastic membrane 304, a first insulating member 306 inserted between the beam portion of the probe and the bottom surface of the elastic membrane, and a first insulating member. It comprises a second insulating member 308 extending downward to approximately the same length as the depth of the beam portion of the probe. The tile 302 is fixed to the surface of the space transformer 30 by a double-sided mounting contact surface 310 that serves as a framework for the upper surface of the elastic film 304 of the tile. The space transformer 30, which is supposed to face the needle card type probe head in the first place, is for removing the needle card type probe head and arranging the contact button 166 of the probe so as to come into contact with the space transformer contact portion 144. It can be replaced with a membrane suspension probe by attaching one or more tiles 302 containing one or more membrane suspension probes 104 on the surface of the space transformer. When the probe tip 168 is pressed into contact with the contact pad on the DUT, the probe 104 rotates around the interface between the contact button 166 and the contact 144 of the space transformer. The end of the beam portion 164 in the vicinity of the probe tip 168 rotates upward to cause local wiping of the probe tip, and the first insulating layer 306 covers the surface of the elastic film 304 that resists the distortion of the restoring force. distort. One or more blank-filled tiles 312 may be mounted near the surface of the space transformer 30 so that the probe head is a continuous surface.

A probe head with a membrane suspension probe can be used in a needle card probe assembly that can utilize a membrane suspension probe, which can be pitched tighter than a needle probe and can have a significantly lower inductance. Can be converted. The distortion of the signal is significantly reduced, allowing inspection of devices operated at higher frequencies and accurate measurements at any frequency.

The present invention can be understood in detail from the above-mentioned many detailed explanations. However, it is well known that those skilled in the art can sufficiently implement it without these detailed descriptions. The invention is not obscured by deliberately not elaborating on other examples, well-known methods, means, components and circuits.

All references in the specification are incorporated herein by reference.

The terms and expressions described in the specification do not limit the invention, and the use of such terms and expressions is limited only to the scope of the invention described in the claims and is equivalent. It is not intended to exclude those with characteristics.

<figref num="1">It is an exploded perspective view of a needle type robe assembly.</figref><figref num="2">It is sectional drawing of the needle card probe head for a needle type probe assembly.</figref><figref num="3">FIG. 5 is a perspective view of a membrane probe assembly bolted to a probe head and a wafer supported on a chuck at a position suitable for probe processing of the assembly.</figref><figref num="4">A low surface showing various parts of the probe assembly shown in FIG. 3, including a partial view of a probe card with support elements and a pervasive membrane assembly with data / signal lines connected to the corresponding lines on the membrane assembly. It is a figure.</figref><figref num="5">It is a side view of the membrane probe assembly shown in FIG. 3 in which a part of the membrane assembly is cut out to expose the hidden part of the support element.</figref><figref num="6">It is a top view of a typical support element.</figref><figref num="7">FIG. 6 is a schematic side view of a support element and membrane assembly tilted to match the starting position of the device to be inspected.</figref><figref num="8">It is the enlarged top view of the central region of the structure of the membrane assembly shown in FIG.</figref><figref num="9">FIG. 9a is a cross-sectional view taken along the line 9a-9b of FIG. 8, where FIG. 9a shows the contact portion before contact, and FIG. 9b shows the same contact portion after contact, moving to the corresponding pad and wiping. Is shown.</figref><figref num="10">The dotted line portion represents the contact portion at the initial stage of contact in FIGS. 9a-9a, and the solid line portion is a schematic side view showing the pad moved further in the vertical direction.</figref><figref num="11">FIG. 6 is a schematic exploded perspective view of a probe assembly comprising a needle probe head suitable for a space transformer and a probe head having a membrane suspension probe.</figref><figref num="12">FIG. 5 is a schematic cross-sectional view of the probe assembly shown in FIG.</figref><figref num="13">FIG. 5 is a schematic cross-sectional view of the tip of a membrane suspension probe in contact with the contact pad of the device under inspection.</figref><figref num="14">FIG. 6 is a schematic cross-sectional view of a probe head suitable for a needle card type space transformer incorporating a second embodiment of a membrane suspension probe.</figref><figref num="15">It is a low side view of a space transformer equipped with a large number of probe tiles in a membrane suspension probe.</figref><figref num="16">It is sectional drawing of the probe head tile including a membrane suspension probe.</figref>