Device for testing semiconductor elements

Abstract

The invention relates to a probe card (1) for testing semiconductor components (5), comprising a plurality of test needles (4) and having a pressure chamber (11), which is provided inside a cylindrical sheath-like part (10) of the device and is open towards the semiconductor component (5) to be tested. Outside the cylindrical sheath-like part (10) a sealing ring (7) is provided which is axially movable. Between the cylindrical sheath-like part (10) and the sealing ring (7) there is a gap (23) in which a slot (25) is provided which is open towards the sealing ring (7). In the slot (25) there is a resiliently radially expandable annular seal (26) which, in its operative position, projects beyond the outer surface (22) of the cylindrical sheath-like part (10) and abuts the inner surface (21) of the sealing ring (7).

Description

[0001] DEVICE FOR TESTING SEMICONDUCTOR COMPONENTS

[0002] The invention relates to a device for testing, in particular for high-voltage testing, semiconductor components with the features of the introductory part of claim 1.

[0003] The invention considers both semiconductor components (hereinafter referred to as "chip") that have not yet been removed (broken out) from semiconductor wafers, and isolated chips that have already been separated from semiconductor wafers.

[0004] Electrical testing of semiconductor components involves testing the voltage withstand capability of high-voltage components such as high-voltage transistors, IGBTs, or diodes by applying high voltage. The chips, which are not yet packaged and are still, for example, stacked (not yet separated) in a semiconductor wafer, are tested via test contacts on the

[0005] Contact surfaces on the front of the chip or a conductive carrier plate on the back of the chip are subjected to high electrical voltage and the electrical properties, such as the leakage current when the component is blocked, are measured.

[0006] During this test, depending on the chip geometry and the magnitude of the test voltage, electric field strengths can occur between contact surfaces on the chip to such an extent that unwanted (spark) arcing occurs between the contact surfaces and through the atmosphere (air). The other chips located next to the chip being tested, on a semiconductor wafer, are usually not contacted on their front side, so no spark arcing occurs on these chips.

[0007] From WO 2020 / 148226 A1, a device for testing components under increased pressure is known. In the known device, a pressure chamber is provided, wherein the lateral boundary of the pressure chamber comprises a ring and an annular part that can be moved perpendicular to the plane of the component to be tested. A velvet-like coating is provided on the end face of the annular part or the ring facing the component to be tested, the fibers of which project from the annular part or the ring towards the component to be tested and bridge the gap between the device and the component.

[0008] A vertical needle card is known from WO 2015 / 106302 Al. The vertical needle card has a housing with a pressure chamber formed by a cylindrical part of the housing. An axially movable sealing ring is provided outside the pressure chamber. The sealing ring is held at a defined distance from the semiconductor device by the Bernoulli effect, which is caused by pressurized gas flowing from the pressure chamber or from channels provided in the sealing ring into the gap between the sealing ring and the semiconductor device.

[0009] In the needle card known from AT 511 398 Bl, the needles, which are bent (bent out) at least once, are guided between the plates by at least one insulating plate, wherein the insulating plate has a frame which is provided on its opposite sides with unidirectional fiber layups. The fiber layups have electrically insulating fibers which are oriented at right angles to each other. The insulating plate is arranged to be slidable in its plane within the needle card.

[0010] In practice, it may be provided that one unidirectional fiber fabric is attached to the top of the frame of the insulating panel and the other unidirectional fiber fabric, in which the fibers are aligned at an angle of 90° to the first fiber fabric, is attached to the bottom of the frame of the insulating panel.

[0011] The device known from AT 511 226 Bl (= WO 2012 / 122578 Al ) for preventing spark discharges during high-voltage testing of semiconductor components (chips) on semiconductor wafers comprises a pressure chamber that can be sealed onto the semiconductor wafer and has a pressurized gas supply, so that the interior of the pressure chamber can be pressurized and thus the ignition voltage for a spark discharge between contact surfaces is higher than the maximum test voltage to be applied. The pressure chamber is connected to a needle card with test needles. The pressure chamber has a movable part that is movable relative to the parts of the pressure chamber connected to the needle card.The movable part of the pressure chamber, designed as a ring seal, is held at a distance from the surface of the semiconductor disk by a gas bearing (air bearing) in the gap between the pressure chamber and the semiconductor disk, with at least one spring provided between the part of the pressure chamber connected to the needle card and the movable part of the pressure chamber.

[0012] DE 100 00 133 Al discloses a prober for pressure sensors. This prober comprises a printhead with an interior open on one side, which can be placed on the pressure sensor with its open end face in such a way that the interior is tightly sealed. DE 100 00 133 Al does not disclose any measures for combining this prober with a vertical needle card, such as the one known from AT 511 398 Al.

[0013] US patent 2004 / 0005792 A1 discloses and describes an electrical contact device in the form of a vertical needle card with S-shaped bent needles. The needles are slidably mounted in holes in at least one plate and are bent. The contact device known from US patent 2004 / 0005792 A1 is intended for establishing an electrically conductive connection between a test device and an electronic component, such as a chip. US patent 2004 / 0005792 A1 contains no indication of combining this needle card with a pressure chamber.

[0014] From AT 511 058 A4, a method and a device for testing pressure sensors, in particular pressure sensor chips of a semiconductor device, are known. AT 511 058 A4 discloses a needle card of the cantilever needle card type. In the device known from AT 511 058 A4 for the electrical and pneumatic testing of pressure sensors, in particular pressure sensor chips, in a semiconductor wafer, the semiconductor wafer is electrically contacted and placed under a defined overpressure in a pressure chamber. The overpressure stressing the semiconductor wafer is detected by a reference pressure sensor. The pressure chamber is arranged on a needle card with test needles and has a part that is movable relative to the needle card. A gas bearing (air bearing) is formed between the end face of the movable part of the pressure chamber facing the semiconductor wafer and the semiconductor wafer.The device known from AT 511 058 A4 allows pressure sensor chips in a semiconductor disk to be tested under defined conditions, whereby testing is possible not only at a defined pressure, but also at pressure fluctuations in the acoustic range.

[0015] A vertical pin card, such as those made from

[0016] Combining the device known from AT 511 398 Bl with a pressure chamber according to AT 511 226 Bl (= WO 2012 / 122578 Al) is not readily feasible if, on the one hand, the function of the pressure chamber placed over the semiconductor device to be tested and, on the other hand, the function of the vertical needle card (vertical test card) are to be retained. In order to maintain the advantageous effects of both the vertical needle card and the pressure chamber, further measures beyond a simple combination are required.

[0017] In known devices (needle cards) with a pressure chamber, sealing the pressure chamber is problematic.

[0018] This is also because the distances between contact surfaces on the semiconductor device are becoming increasingly smaller, which necessitates higher pressures in the pressure chamber to prevent (spark) arcing between the contact surfaces of the semiconductor device. This applies particularly to semiconductor devices based on silicon carbide (SiC) and gallium nitride (GaN).

[0019] Even if the semiconductor devices (wafers) being tested contain multiple chips that can be tested simultaneously, and therefore the diameter of the pressure chamber is larger, the problem of sealing arises. In both cases, which can also occur simultaneously, pressure losses make it difficult and often impossible to build up the required pressure in the pressure chamber.

[0020] In particular, pressure loss occurs because the pressurized gas (usually compressed air) escapes from the pressure chamber through the gap between a cylindrical part of the device (needle card) and the sealing ring which is axially displaceable outside this part.

[0021] Publications that define the general state of the art are US 2015 / 0015285 Al, WO 2012 / 023180 Al, US 2011 / 0156735 Al, DE 10 2021 211 263 Al, CN 104380448 A, US 7, 436, 195 B2, US 2013 / 0147506 Al and AT 14209 Ul.

[0022] The invention is based on the objective of avoiding or at least minimizing pressure losses from pressure chambers of devices of the aforementioned type.

[0023] This problem is solved with a device that has the features of claim 1.

[0024] Preferred and advantageous embodiments of the invention are the subject of the dependent claims.

[0025] Thanks to the seal provided in the gap between the cylindrical part of the device and the sealing ring, unwanted pressure losses are reduced or avoided.

[0026] Since the seal according to the invention is ring-shaped and elastically expandable, the desired sealing effect is achieved particularly well.

[0027] When the seal is received in an outwardly open, annular groove in the cylindrical part with axial and radial clearance, an advantageous effect results that supports the sealing action. The seal is pressed not only axially against a wall of the groove, but also radially against the inner surface of the sealing ring by gas entering the gap between the cylindrical part and the sealing ring.

[0028] The seal provided according to the invention also has the advantage that, despite the inevitable radial expansion of the sealing ring, which occurs particularly in the case of sealing rings with a larger diameter, increasing pressure losses are prevented / reduced.

[0029] The seal is, for example, a ring that is interrupted (“slit”) at one point, so that the elastic expansion of the seal is particularly easy to achieve.

[0030] The seal provided according to the invention also has the advantage that, when testing semiconductor components at elevated temperatures, a reduction in the gap between the cylindrical part and the sealing ring caused by the thermal enlargement of the radial dimension of the cylindrical part does not lead to restricted mobility of the sealing ring, because the gap can be larger from the outset.

[0031] The cross-sectional shape of the ring-shaped seal is largely arbitrary. Polygonal and (circular) round cross-sectional shapes are possible.

[0032] Plastic, for example polyetheretherketone (PEEK), has proven to be a suitable material for the ring-shaped seal.

[0033] In the invention, the gap between the sealing ring and the cylindrical shell-shaped part can be larger than the sealing gaps in known devices due to the seal provided there. This helps to avoid problems – e.g., the sealing ring becoming stuck to the outside of the pressure chamber – when the diameter of the pressure chamber increases thermally.

[0034] In one exemplary embodiment, a retaining element, such as a retaining ring, is provided radially outside the sealing ring to secure it to the device. This retaining element may have radially inward-facing projections which, together with radially outward-facing tongues, prevent the sealing ring from detaching from the cylindrical part. In this way, the sealing ring can be secured to the retaining element, for example, in a bayonet-like manner, while still remaining axially adjustable relative to the cylindrical part. The retaining element prevents the sealing ring from sliding axially off the cylindrical part of the pressure chamber, particularly when the device (needle card) is not in contact with the semiconductor device under test (e.g., a wafer).

[0035] Further details, features and advantages of the device according to the invention will become apparent from the following description of exemplary embodiments with reference to the drawings. It shows:

[0036] Fig. 1 shows a device in a partial axial section, Fig. 2 shows another embodiment of the device in a partial axial section.

[0037] Fig. 3 shows a partial axial section of a first embodiment of the seal.

[0038] Fig. 4 shows a partial axial section of another embodiment of the seal.

[0039] Fig. 5 shows a partial axial section of a third design form of the seal, and

[0040] Fig. 6 shows a partial axial section.

[0041] Guide form with a retaining ring for the sealing ring.

[0042] The drawings show, in part schematically, only parts of a device according to the invention that are essential for the invention, using a vertical needle card as an example.

[0043] An embodiment of a device according to the invention ("vertical needle card") for testing semiconductor components 5, shown in Fig. 1, comprises a needle card 1 (circuit board) to which needles 4 ("probes"), which may be angled and bent (bent out) at least once, are attached. A housing 8 is arranged on the needle card 1, comprising a flange-like part 9 and a cylindrical part 10. The cylindrical part 10 of the housing 8 encloses a pressure chamber 11. A guide 3 (plate, for example made of ceramic material) for the needles 4 is provided between the flange-like part 9 of the housing 8 and the needle card 1.A further guide 3 (plate, for example made of ceramic material) for the free ends of the needles 4 of the needle card 1, i.e., the ends that are associated with and applied to the semiconductor device 5 to be electrically tested, is provided in the area of ​​the open end of the pressure chamber 11, i.e., at the free edge of the cylindrical shell-shaped part 10 that faces away from the flange-like part 9 of the housing 8. A unidirectional fiber fabric or a nonwoven material can be provided as an insulating layer between the plates serving as guides 3 for the needles 4 (not shown).

[0044] Electrical insulation of the parts of the needles 4 located in the pressure chamber 11 can also be achieved by an insulating coating on the needles 4, at least in their areas located in the pressure chamber 11. In this way, the needles 4 are electrically insulated from each other (even without guides 3).

[0045] A channel 2 is recessed in the needle card 1, which is intended for supplying compressed gas (compressed air) into the pressure chamber 11. The supplied compressed gas creates overpressure in the pressure chamber 11, which is enclosed by the cylindrical shell-shaped part 10 of the housing 8, so that either a high-voltage test of semiconductor devices 5 or an electrical and pneumatic test of pressure sensors (pressure sensor chips) in semiconductor devices 5 can be performed.

[0046] The cylindrical shell-shaped part 10 of the housing 8, which delimits the pressure chamber 11, is surrounded in the embodiment shown in Fig. 1 by a sealing ring 7 which is movable axially (axis 20) relative to the needle card 1, i.e. transversely to the needle card 1. In the embodiment shown in Fig. 1, the sealing ring 7 is held relative to the top of the semiconductor device 5 by means of a dynamic gas bearing (air bearing) 13 and forms a gap seal to the semiconductor device 5.

[0047] In the embodiment shown in Fig. 1, the pressurized gas (compressed air) required for the gas bearing (air bearing) 13 is supplied via the pressure chamber 11. The gas bearing 13 dynamically supports the sealing ring 7 as soon as pressure has built up in the pressure chamber 11.

[0048] In the embodiment shown in Fig. 2, the gas bearing (air bearing) 13 formed in the gap between the top surface of the semiconductor component 5 and the sealing ring 7 is pressurized with compressed gas (compressed air) not via the pressure chamber 11, but via one of the channels 2. Specifically, an annular channel 14, open radially outwards, is provided on the outside of the cylindrical shell-shaped part 10 of the housing 8, into which the channel 2 opens. The channel 14 is opposite an annular channel 15, open inwards, on the inside of the sealing ring 7. Several lines (channels) 16 lead away from the annular channel 15 in the sealing ring 7, opening into the annular end surface 17 of the sealing ring 7 facing the semiconductor component 5, i.e., into the gap 13 located there between the sealing ring 7 and the semiconductor component 5. In Fig.

[0049] 2 The gas bearing (air bearing) 13 is designed as a static gas bearing (air bearing). This static gas bearing 13 forms a gap seal between the end surface 17 of the sealing ring 7 and the top surface of the semiconductor device 5, independent of the pressure build-up in the pressure chamber 11.

[0050] The cylindrical shell-shaped part 10 and the sealing ring 7 of the (vertical) needle card 1 are essentially rotationally symmetrical (with axis 20) in the illustrated embodiments.

[0051] Outside the cylindrical shell-shaped part 10, a sealing ring 7 is provided which is movable in the direction of the axis 20 (axially). The sealing ring 7 can, for example, be designed as is known from EP 2 659 279 Bl (there movable part 13) or from EP 3 025 159 Bl (there sealing ring 7 ).

[0052] Between the (cylindrical) inner surface 21 of the sealing ring 7 and the (cylindrical) outer surface 22 of the cylindrical part 10 there is a gap 23, so that the sealing ring 7 is axially adjustable relative to the cylindrical part 10, i.e. in the direction of the axis 20 (arrow 24 ).

[0053] In the outer surface 22 of the cylindrical part 10, an annular groove 25 is provided, open radially outwards, i.e. towards the inner surface 21 of the sealing ring 7. A ring seal 26 is received in the groove 25 as a seal such that the ring seal 26 bears against the inner surface 21 of the sealing ring 7.

[0054] The groove 25 and the ring seal 26 are dimensioned such that the ring seal 26 is movable in the groove 25 both radially (transverse to the axis 20) and axially (parallel to the axis 20).

[0055] The ring seal 26 is radially expandable. This is achieved, for example, and preferably, by the ring seal 26 having an interruption. The ring seal 26 is, for example, slotted. Due to the interruption provided in it, the ring seal 26 is (only) flexurally elastic, but not longitudinally elastic (extensible). This design of the ring seal 26 has the advantageous effect that the ring seal 26 expands radially under the influence of gas passing through the gap 23 from the pressure chamber 11, thus assuming a larger diameter, and is pressed against the inner surface 21 of the sealing ring 7. Simultaneously, the ring seal 26 is pressed axially against the wall 27 of the groove 25, which is furthest from the open side of the pressure chamber 11. The aforementioned forces acting on the ring seal 26 are symbolically represented in Fig. 3 by arrows 28 and 29.

[0056] The ring seal 26 can have different cross-sectional shapes, and can be, for example, rectangular (Fig. 3), circular (Fig. 4) or L-shaped (Fig. 5).

[0057] This ensures a good seal for pressure chamber 11.

[0058] The sealing ring 7 and the cylindrical shell-shaped part 10 of the embodiments shown in Figs. 3 to 6 can also be designed as shown in Fig. 2.

[0059] Since in the device according to the invention the sealing ring 7 only needs to be “loosely” guided on the cylindrical part 10, a measure can be provided to secure the sealing ring 7 to the cylindrical part 10.

[0060] An example of this securing mechanism is shown in Fig. 6. In the example shown in Fig. 6, a retaining element, for example a retaining ring 30, connected to the needle card 1, is provided outside the sealing ring 7. Several, e.g., three, projections 31 extend radially inwards from the inside of the retaining ring 30. Several, e.g., also three, tongues 32 are provided on the sealing ring 7, extending radially outwards from the outside of the sealing ring 7. The tongues 32 can be moved by rotating the sealing ring 7 into a position in which they engage the projections 31 of the retaining ring 30 with clearance. In the operating position of the device according to the invention (needle card 1) shown in the figures, the tongues 32 of the sealing ring 7 are arranged above the projections 31 of the retaining ring 30 when the sealing ring 7 is secured to the retaining ring 30.Thus, the sealing ring 7 is held axially movable (arrow 24) on the device (needle card 1) and cannot detach from the device even when the device, in its operating position, is approached with the open side of its pressure chamber 11 leading a semiconductor component 5 to be tested located below the device during testing.

[0061] In summary, an embodiment of the invention can be described as follows:

[0062] A needle card 1 for testing semiconductor devices 5 with several test needles 4 has a pressure chamber 11, which is provided within a cylindrical part 10 of the device and is open towards the semiconductor device 5 to be tested. An axially movable sealing ring 7 is provided outside the cylindrical part 10. A gap 23 is provided between the cylindrical part 10 and the sealing ring 7, in which a groove 25 open towards the sealing ring 7 is provided. An elastically radially expandable ring seal 26 is received in the groove 25, which, in its effective position, projects beyond the outer surface 22 of the cylindrical part 10 and bears against the inner surface 21 of the sealing ring 7.

Claims

Claims:

1. Device, in particular a needle card, preferably a vertical needle card (1), for testing semiconductor devices (5) with several needles (4) and with a pressure chamber (11) which can be pressurized, wherein the pressure chamber (11) is provided within a cylindrical shell-shaped part (10) of the device and is open towards the semiconductor device (5) to be tested, wherein a sealing ring (7) is provided axially (arrow 24) movable outside the cylindrical shell-shaped part (10) and wherein a gap (23), in particular annular, is provided between the cylindrical shell-shaped part (10) and the sealing ring (7), characterized in that a groove (25) open towards the sealing ring (7) is provided in the area of ​​the gap (23) in the cylindrical shell-shaped part (10) and that a radially elastically expandable ring seal (26) is received in the groove (25).which in its effective position projects beyond the outer surface (22) of the cylindrical shell-shaped part (10) and rests against the inner surface (21) of the sealing ring (7).

2. Device according to claim 1, characterized in that the ring seal (26) is received in the groove (25) with radial and axial clearance.

3. Device according to claim 1 or 2, characterized in that the ring seal (26) has an interruption.

4. Device according to one of claims 1 to 3, characterized in that the ring seal (26) is essentially only flexible and is made of plastic, for example PEEK.

5. Device according to one of claims 1 to 4, characterized in that the cross-sectional shape of the ring seal (26) is polygonal, in particular rectangular or square, or round, in particular circular.

6. Device according to claim 5, characterized in that the cross-sectional shape of the ring seal (26) is L-shaped.

7. Device according to one of claims 1 to 6, characterized in that the sealing ring (7 ) is axially movably secured to the device by a retaining part, in particular a retaining ring (30).

8. Device according to claim 7, characterized in that radially inwardly projecting projections (31 ) are provided on the retaining part, in particular the retaining ring (30) and radially outwardly projecting tongues (32 ) are provided on the sealing ring (7 ), and that the tongues (32 ) are aligned with the projections (31 ) when the sealing ring (7 ) is secured, in particular engaging behind the projections (31 ).

9. Device according to claim 8, characterized in that, with the sealing ring (7) secured, there is play in the axial direction between the projections (31) and the tongues (32).

10. Device according to one of claims 1 to 9, characterized in that the cylindrical shell-shaped part (10) which laterally delimits the pressure chamber (11) is positioned radially outside of several chips provided in a semiconductor device (5) to be tested, in particular a wafer.

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